In this article “Application of heat exchanger” and application of heat exchanger related facts that will be talk. Heat exchanger is a device which one exchanges the heat between two different temperature fluids.
13+ Application of Heat Exchanger is listed below,
Warm the muscles of the back with the heating pad:-
From the definition of heat exchanger we can understand that two matters when they are stays in different temperature start to exchanging temperature until they reach to the same temperature. The matters can be separated by a wall which will be stays in solid state to stave off amalgamation or the matters can be stay in direct contact to each other. For the case of warm the muscles of the back with the heating pad the matters are divided by solid state .
When warm heating pad is applied in the back of the patient that time heating pad contain high temperature and back of the patient stays at low temperature but when two different temperature is comes closer they start to heat exchanging between to each other and as a result the temperature starts to come in equilibrium condition. The patient easily can take the temperature from heating pad and gets comfort from his back muscle pain.
Mixing hot food item with a spoon:-
For the case of mixing hot food item with the help of spoon the matters are not divided by solid state they stay at direct contact to each other. When warm food item is comes to connect with cold spoon that time hot food item contain high temperature and spoon stays at low temperature but when two different temperature is comes closer they start to heat exchanging between to each other and as a result the temperature became starts to come in equilibrium condition. So, mixing hot food item with a spoon is another example of application of heat exchanger.
Mixing cold food item with a spoon:-
For the case of mixing cold food item with the help of spoon the matters are not divided by solid state they stay at direct contact to each other. When cold food item is comes to connect with comparative hot spoon that time hot food item contain low temperature and spoon stays at high temperature but when two different temperature is comes closer they start to heat exchanging between to each other and as a result the temperature became starts to come in equilibrium condition. So, mixing cold food item with a spoon is another example of application of heat exchanger.
Making of tea:-
For the case of making of tea the matters are not divided by solid state they stay at direct contact to each other. When warm water is mixing with the cold milk that time hot water contain high temperature and cold milk stays at low temperature but when two different temperature is comes closer they start to heat exchanging between to each other and as a result the temperature became starts to come in equilibrium condition. So, making of tea is another example of application of heat exchanger.
Shaking hands:-
Shaking hand between two different people is another example of application of heat exchanger. When two hands are shaking that time the body temperature of two people definitely stay at different temperature but when the hands get closer that time heat exchanging started and as a result the temperature comes in an equilibrium condition.
Touch into the overheated oven the matters are separated by a wall which will be stays in solid state. For the case when warm heated pan is touched by hand that time heated oven contain high temperature and hand stays at low temperature but when two different temperature is comes closer they start to heat exchanging between to each other and starts to come in equilibrium condition for this reason when overheated oven is touched injury can be appear.
Touch ice cube:-
Touching an ice cube is another example of application of heat exchanger. For the case when in a cool ice cube is touched by hand that time ice cube contain low temperature and hand stays at high temperature but when two different temperature is comes closer they start to heat exchanging between to each other and starts to come in equilibrium condition for this reason when cooled ice cube is touched we feel cold.
Refrigeration system:-
From the term of refrigeration we can get that cooling an area, system or matter to decreases or maintain the temperature below the surrounding one the rejection of heat at a higher temperature. Refrigeration a human made artificial cooling system. Energy that is present in state of heat is rejected from a reservoir which stays in low temperature to a reservoir which stays in high temperature. The application of refrigeration is in wide range such as cryogenics, household refrigerators, air conditioning and industrial freezers.
Image – Commercial refrigeration; Image Credit – Wikipedia
Humans:-
The nasal passage of the human being is works as a heat exchanger. By the help of nasal passage cold air is enter and hot air is exist. The effectiveness of the nasal passage easily can be examined putting the hand in front of exhaling and face, firstly by the nose and in next step by the mouth.
Air conditioning:-
With the air conditioning system in certain place or maintain the temperature, air purity and relative humidity below the surrounding one the rejection of heat at a higher temperature. The air conditioning system is applied for personal comfort. It industries air conditioning system widely used to ensure appropriate operation of parts or machinery.
Image – Air conditioning condenser units outside a building; Image Credit Wikipedia
Countercurrent heat exchangers naturally appear in the circulation system of birds, fish and marine mammals. Arteries into the skin bearing warm blood are intertwined along from the skin bearing cold blood, causing the warm blood of the arterial to transfer heat with cold blood venous.
Image – Counter-current exchange conservation circuit; Image Credit – Wikipedia
Petroleum refineries:-
Petroleum refineries or oil refineries is a engineering industrial field where the petroleum is transfer and after that the petroleum is refined into some useful products like kerosene, petroleum naphtha, heating oil, gasoline, fuel oils, diesel fuel and many more.
Sewage arrangement:-
Sewage arrangement is a waste treatment process by which contaminates are removed from sewage to created an effluent which is perfect for exit to the environment.
Image – Sewage arrangement plant; Image Credit – Wikipedia
Advantages of sewage arrangement:-
Time efficient
Eco friendly
Design is simple
Easy installation
Experts not needed
Maintenance cost low
Occupies meager space
Disadvantages of sewage arrangement:-
Power supply needed
Maintenance needed
Frequent Asked Questions:-
Question: – Describe the classifications of heat exchanger.
Solution: – The classifications of heat exchanger is listed below,
In this article “Crankshaft types” and how crankshaft types are related with others facts that will be discuss. In the system of power transmission crankshaft plays a very important role.
The crankshaft is a shaft which is rotate in a motion and transfer piston’s reciprocating motion to rotation motion. The types of crankshaft is listed below,
The parts of the welded crankshafts such are journals, crank web, crank pin, crank arms are separately manufactured and after that welded with each other. Among the all types of the crankshafts welded crankshaft is stronger and stable. For manufactured the welded crankshaft became very for costly and maintenance is also quite high for this reason in general application the welded crankshaft is not preferred.
Fully built crankshaft:-
In the fully built up crankshaft by its name it define that all components of the fully built crankshaft is manufactured and fabricated separately with taking helping of the pieces of the matter which are multiple separate. The parts which are machined separately they are crankpins, journals and crank webs. The parts are heated and finally artificially shrink fitted together.
When the parts are cooled loosing the excess amount heat the size of the parts are shrink and make a tight grip to each other. The end portion of the connecting rod of the fully built crankshaft is made with a single solid piece of the material.
The making of the fully built crankshaft is easy because small size parts are assembly to make bigger size equipment. The weight of the fully built crankshaft is heavier.
Semi built crankshaft:-
By the name of semi built crankshaft we easily can recognize that the every parts of the crankshaft is not arrange together some of the parts are only constructed and forged together to make a whole crankshaft design. The parts which are shaped, forged, built together in the semi built crankshaft are bearings, crank web. In diesel engine semi built crankshaft is used.
Billet crankshaft:-
With the help o the 4340 alloy steel the billet crankshaft is manufactured. The 4340 alloy made with chromium, nickel, molybdenum and aluminium. The billet crankshaft transfer maximum amount of power to the load. Minimal balancing is required to the billet crankshaft and also it have lowest amount of machining time for this reason in the system of power transmission this type of crankshaft widely used.
Forged crankshaft:-
By the name of forged crankshaft we easily can recognize that with the help of forging process the forged crankshaft is make. A block of metal or with a single piece of metal the forged and finally crankshaft shaped is given to it. For arranging the all parts of the forged process welding is not required. The engines where need medium speed like generator there only forged crankshaft can be used.
The engines which are bulky and heavy like two stroke engines there forged crankshaft is not suitable al all. Improving the strength of the forged engine induction hardening process is used. It is robust and moderate economical to use.
Image – Forged Crankshaft; Image Credit – Wikipedia
Solid single crankshaft:-
From the term of the solid single crankshaft we can recognize that this type of crankshaft is made with solid one single piece of material. The solid single crankshaft can work in bothlow speed and high speed for this particular reason in multi cylinder engine solid single crankshaft widely used. The end portion of the connecting rod with two pieces of material solid single crankshaft is made. This structure passes through cyclic tension and load during firing.
The solid single crankshaft is stressed for the reasons of axial vibration torsional vibration, misalignment of the main bearing.
Cast crankshaft:-
Cast crankshaft is made with casting malleable iron. In the engines of diesel and petrol cast crankshaft is used in a wide range. The manufacturing cost is very less comparative to the other types of crankshaft and its maintenance cost is also not too high. For improving tensile strength to the cast crankshaft heat preparation is done and for this reason rate of tear and wear is decreases. The lifetime of this crankshaft is also high.
The crankshaft of the diesel engine is made with alloy steel. For making the crankshaft of the engine at first alloy steel is heated at very high temperature and after that moulded in shape taking the help of forging die. The engine of the diesel have longer stroke comparative to bore diameter, for this particular reason the crankshaft use in the diesel engine larger than the other parts. Billet crankshaft is use in diesel engine for improving the performance than the other classifications of the crankshaft.
The types of crankshafts in marine engine are listed below,
Fully built crankshaft
Semi built crankshaft
Welded crankshaft
Forged crankshaft
Image – Continental engine marine crankshafts, Image Credit – Wikipedia
Frequent Asked Questions:-
Question: – Explain the causes behind the unbalancing of crankshafts.
Solution: – The causes behind the unbalancing of crankshafts is listed below,
Explosion or crankcase fire
For the reason of torsion and twist is evolved in the crankshaft.
For the reason of power stroke. After completing the power stroke inside the engine the piston of the engine exerted a jerk force inside the crankshaft thus the crankshaft can make rotation.
The motion of the reciprocating of the piston of the engine inside the chamber of the combustion.
Image – Flat-plane crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black); Image Credit – Wikipedia
Question: – Mention the symptoms by which we can recognize the bad conditions of the crankshaft.
Solution: – The symptom by which we can recognize the bad condition of the crankshaft are listed below,
Image – Schematic of operation of a crank mechanism; Image Credit – Wikipedia
Noise:-
When the excessive unwanted noise is produce inside the engine that time we can recognize the bad condition of the crankshaft.
Knocking:-
When inside the crankshaft main journal and connecting rod bearing extreme wear is produce that time knocking is appear in the engine of the machine. Knocking is the symptom by which we can recognize the bad condition of the crankshaft.
Difficulty in starting:-
When the system crate problem in starting that time we can recognize the bad condition of the crankshaft.
Excessive vibration of the engine:-
The CKP sensor easily can detect and bounds the generated vibration of the engine of the vehicle to produce stable power input. If unwanted excessive amount of vibration is produce in the engine that helps us to recognize bad condition of the crankshaft.
Stalling and Backfiring:-
When the default position sensor failure of crankshaft is happened that time backfiring and stalling is occur. The CKP sensor failure causes the engine of the system shut down abruptly and after that starting the engine of the system without any reason. The symptom by which we can recognize the bad condition of the crankshaft among them stalling and backing one of them.
Question: – Write the reasons failure behind the diesel engine.
Solution: – The reasons failure behind the diesel engine is listed below,
Misaligned crankshaft
Develop of the cracks on the fillets.
Excessive amount of vibration is appearing for the reason of torsion that can created cracks in the main journals and crankpin.
Excessive speeding of the engine on load.
Stray current or eddy current is passes from the faulty alternator.
Cylinder of the engine is over pressurized for the reason of hydraulic lock for the reason of water leakage in the system’s engine.
Question: – Write the advantages of crankshaft.
Solution: – The advantages of crankshaft is listed below,
Increases the power of the engine
Provides better torque
Greater efficiency
Smooth running
Question: – Write the disadvantages of crankshaft.
Solution: – The disadvantages of crankshaft is listed below,
In this article the topic named “Darcy friction factor” and Darcy friction factor related facts will be discuss. In fluid mechanics the Darcy friction factor equation is play a very important role.
The Darcy friction factor is a physical parameter which is related to head loss or loss of pressure for the reason of friction along the certain amount of length of a coil or pipe to the average velocity of the incompressible fluid. The Darcy friction factor is a dimensionless physical quantity.
What is Darcy friction factor?
The Darcy friction factor is a physical parameter which is use to describe the loss for a coil or pipe due to friction. The Darcy friction factor is applicable for both open channel flow and close channel flow.
The Darcy friction factor is a physical parameter which is describe as it is a physical quantity which is use for calculate the frictional energy loss. The Darcy friction factor is cased for resistance due to friction and velocity of the incompressible fluid inside a coil or pipe.
The Darcy friction factor widely used in turbulent flow for calculating the amount of head loss during the friction in the pipe.
Darcy friction factor formula:
The equation for Darcy friction factor is given below,
Hf = 4fLv2/2gD
Where,
Hf= Pressure loss or head loss
f = Coefficient of friction factor or Coefficient of friction factor
L = Length of the coil or pipe
v = Velocity of the incompressible fluid
g = Acceleration due to gravity (value of g is 9.8 meter per square second)
D = Diameter of the coil or pipe
Pressure loss equation:-
In a cylindrical coil or pipe where incompressible fluid is flow in a motion, the cylindrical coil or pipe which have a uniform diameter D, the pressure loss is appear during the viscous effect which is express as Δp is directly proportional to the length of the cylindrical coil or pipe can be express as with the help of Darcy – Weisbach equation,
Where,
Δp/L= The amount of pressure loss of per unit length is, which express as Pacals per meter
fD = Coefficient of friction factor or Coefficient of friction factor
ρ = The density of the fluid which is express as kg per cubic meter
Head loss form:-
The term of head loss which is express as Δh is the pressure loss appears for reason of friction in term of same length of a column of the incompressible fluid.
The mathematical form of the head loss is,
Δp =ρgΔh
Δh= The head loss appears for reason of friction in term of same length of a coil or pipe and unit is meter.
g = Acceleration due to gravity (value of g is 9.8 meter per square second)
It is beneficial the head loss appears for reason of friction in term of same length of a coil or pipe is,
Where,
L = Length of the coil or pipe and unit is meter
Darcy – Weisbach equation can be writing for head loss,
In form of volumetric flow:-
The relation between volumetric flow rate and mean flow velocity is,
Q = A * <v>
Where,
Q = Volumetric flow rate unit is cubic meter per second
A = Cross sectional area of the coil or pipe and unit is square meter
v = Velocity of the incompressible fluid which is express as meter per second
In a coil or pipe the fluid is flow with pipe diameter D_c,
Darcy – Weisbach equation can be written as,
Shear stress form:-
Darcy – Weisbach equation can be in form of shear stress,
When the value of Reynolds number is less than 2000 this type of flow called laminar flow.
Mathematical analysis of the turbulent flow is easy.
Velocity of the turbulent flow is too low.
Regular movement is appearing in fluids which are flow in a motion in laminar flow.
Laminar flow in general very rare type of flow.
The velocities profile of the flow laminar the wall of the pipe or rod maximum.
The velocity profile of the flow laminar in the center section of the rod or pipe is minimum.
Average motion is appearing in which side fluid is flowing.
Image – A closeup view of water pouring down; Image Credit – Wikipedia
Darcy friction factor for turbulent flow:
Maximum system of the fluid in the nuclear facilities is work with the flow type of turbulent flow. The resistance of this flow obey the equation of Darcy – Weisbach.
The friction of the turbulent flow is measurement of the shear stress which is applied in the wall of a rod or pipe during the flow of turbulent. The flow of turbulent is obeying the equation of Darcy – Weisbach which is directly proportional to square of mean velocity of the flowing fluid in a certain area.
Turbulent flow:-
Reynolds number is more than 3500 .
Velocity is too high.
Irregular movement is appearing
Average motion is appearing in which side fluid is flowing.
The velocity profile of the flow turbulent in a certain area is quickly drops when it comes to the wall of the pipe or rod.
The velocity profile of the flow turbulent in a certain area is clearly flat when it comes to the center section of the rod or pipe
Friction factor for turbulent flow formula:
The Colebrook–White equation is define as f for the Darcy friction factor, the function of for Reynolds number as Re, pipe relative roughness express as, ε / Dh for both smooth pipes and rough pipes.
The friction factor for turbulent flow formula is,
or,
Where,
Dh (m , ft) = Hydraulic diameter for filling the fluid in circular conduits
Dh = D= Inside diameter of the area from where flow of turbulent is flowing
Rh (m , ft) = Hydraulic radius for filling the fluid in circular conduits
Rh = D/4= Inside diameter of the area from where flow of turbulent is flowing/4
The equation of Colebrook is solved by numerically for its implicit nature. Now a day Lambert W function is also use to obtain outspoken reformulation the equation of Colebrook.
a = 2.51/Re
or,
10-1/2 = ax +b
p = 10-1/2
We will get,
px = ax + b
Expanded forms:-
Additional mathematical form of the equation of Colebrook is,
Where,
1.7384…. = 2 log (2 * 3.7) = 2 log (7.4)
18.574 = 2.51 * 3.7 * 2
And,
Or,
Where,
1.1364…. = 1.7384… = – 2 log (2) = 2 log
(7.4) – 2 log (2) = 2 log (3.7)
9.287 = 18.574/2 = 2.51 * 3.7
Darcy friction factor chart:
Darcy friction factor chart is combination of four physical parameters such as, pressure loss coefficient, Reynolds number, and relative roughness of the coil or pipe and diameter ratio of the coil or pipe.
Darcy friction factor chart is dimensionless physical factor with the help of Darcy – Weisbach equation can be written as,
Pressure drop can be calculate as,
Or,
Image – Darcy Friction Factor Chart; Image Credit – Wikipedia
The expression for Darcy friction factor for laminar flow is,
In the flow of turbulent the relation between Reynolds number represent as Re, friction factor represent as fD, and relative roughness represent as ∈/D is complicated.
The expression for Darcy friction factor for turbulent flow is,
Darcy friction factor for different materials:
The Darcy friction factor for different material is given below,
Pipe material
Absolute roughness
Feet
Microns
Copper or drawn brass
0.000005
1.5
Commercial steel
0.000150
45
Concrete
0.001 – .01
300 – 3000
Wood stave
0.0006 – 0.003
200 – 900
Wrought iron
0.000150
45
Riveted steel
0.003 – 0.03
900 – 9000
Darcy friction factor for pipe:
The moody chart or friction factor for pipe is plotted the relative roughness of a coil or pipe which is express as ∈/D and Reynolds number.
Darcy friction factor for water:
The moody chart or friction factor is for water derives as the pressure loss of water n a coil or pipe for the reason of friction between the pipe and the water flow inside of it.
Compressor isentropic efficiency is a crucial parameter that measures the performance of a compressor. It is a measure of how effectively a compressor can convert the input power into useful work by compressing the gas. In simple terms, it tells us how close the compressor’s actual performance is to the ideal, reversible process known as isentropic compression. The higher the isentropic efficiency, the better the compressor’s performance. This efficiency is influenced by various factors such as the design of the compressor, the type of gas being compressed, and the operating conditions. Understanding compressor isentropic efficiency is essential for engineers and technicians involved in the design, operation, and maintenance of compressors, as it helps in optimizing their performance and energy consumption. In this article, we will delve deeper into the concept of compressor isentropic efficiency, its significance, and the factors affecting it. So, let’s get started!
Key Takeaways
Compressor isentropic efficiency is a measure of how well a compressor can convert input power into useful work.
It is calculated by comparing the actual work done by the compressor to the ideal work that would be done in an isentropic process.
Higher isentropic efficiency indicates a more efficient compressor, as it can deliver more work output for the same input power.
Factors such as design, operating conditions, and maintenance affect the isentropic efficiency of a compressor.
Improving compressor isentropic efficiency can lead to energy savings and reduced operating costs.
Definition of Isentropic Efficiency
Isentropic efficiency is a crucial parameter used to evaluate the performance of compressors. It measures how effectively a compressor can compress a gas without any losses due to heat transfer or friction. In simple terms, it is a measure of how close a compressor’s actual performance is to the ideal, reversible, adiabatic compression process known as the isentropic process.
The isentropic process is a theoretical concept in thermodynamics where a gas undergoes a reversible and adiabatic compression or expansion. During this process, there is no heat transfer between the gas and its surroundings, and there are no losses due to friction. The isentropic process is often used as a reference to compare the actual performance of compressors.
Isentropic efficiency is defined as the ratio of the actual work done by the compressor to the work that would be required in an ideal, isentropic compression process. It is denoted by the symbol ηs (eta-s). The higher the isentropic efficiency, the closer the compressor’s performance is to the ideal isentropic process.
Importance of Isentropic Efficiency in Compressors
Isentropic efficiency plays a vital role in determining the overall performance and energy efficiency of compressors. It directly affects the power consumption, heat transfer, and the amount of work required to compress a gas.
Energy Efficiency: Compressors are widely used in various industries, including refrigeration, air conditioning, gas turbines, and more. In these applications, energy efficiency is of utmost importance. By understanding and optimizing the isentropic efficiency of compressors, engineers can design more efficient systems that consume less energy and reduce operating costs.
Power Consumption: The isentropic efficiency of a compressor directly affects the power required to compress a gas. A higher isentropic efficiency means that the compressor can achieve the desired pressure with less work, resulting in lower power consumption. This is particularly important in large-scale applications where compressors operate continuously and consume a significant amount of energy.
Heat Transfer: In compressors, heat transfer occurs due to the compression process. The higher the isentropic efficiency, the lower the heat transfer losses. By minimizing heat transfer, the compressor can maintain a lower discharge temperature, which is crucial for the longevity and reliability of the system.
Typical Isentropic Efficiency of Compressors
The isentropic efficiency of compressors varies depending on their design, operating conditions, and the type of gas being compressed. Different types of compressors, such as centrifugal compressors and axial compressors, have different typical isentropic efficiencies.
Centrifugal Compressors: Centrifugal compressors are commonly used in applications that require high flow rates and moderate pressure ratios. They are known for their high isentropic efficiency, typically ranging from 75% to 85%. However, it is important to note that the efficiency of centrifugal compressors can vary significantly based on their specific design and operating conditions.
Axial Compressors: Axial compressors are widely used in aircraft engines, power plants, and other applications that require high-pressure ratios. They typically have isentropic efficiencies ranging from 85% to 90%. Axial compressors are known for their excellent efficiency and are often used in applications where energy efficiency is critical.
Enthalpy Entropy Diagram
Enthalpy Entropy Diagram
It is important to note that these values are general guidelines, and the actual isentropic efficiency of a compressor can vary based on factors such as design, maintenance, and operating conditions. Manufacturers often provide performance maps or curves that show the efficiency characteristics of their compressors at different operating points.
In conclusion, understanding compressor isentropic efficiency is crucial for evaluating compressor performance, optimizing energy efficiency, and reducing operating costs. By considering the isentropic efficiency, engineers can design and operate compressors more effectively, resulting in more efficient and reliable systems.
The Science Behind Compressor Isentropic Efficiency
A. Thermodynamics and Isentropic Efficiency
In the world of compressors, isentropic efficiency plays a crucial role in determining their performance. To understand compressor isentropic efficiency, we need to delve into the realm of thermodynamics. Thermodynamics is the branch of physics that deals with the relationships between heat, work, and energy. It provides us with the tools to analyze and optimize the performance of various energy conversion systems, including compressors.
One key concept in thermodynamics is the isentropic process. An isentropic process is an idealized process that occurs without any heat transfer to or from the system. In other words, it is a process that is both adiabatic (no heat transfer) and reversible (no irreversibilities or losses). Isentropic processes are often used as a reference for analyzing the performance of real-world processes, such as those occurring in compressors.
Isentropic efficiency, denoted by η_isen, is a measure of how well a compressor is able to achieve an isentropic process. It is defined as the ratio of the actual work done by the compressor to the work that would be required if the process were isentropic. In simple terms, isentropic efficiency tells us how close a compressor is to an ideal, lossless compressor.
B. Isentropic Compression Efficiency Formula
The isentropic compression efficiency of a compressor can be calculated using the following formula:
η_isen = (h1 – h2s) / (h1 – h2)
In this formula, h1 represents the enthalpy of the gas at the compressor inlet, h2s represents the enthalpy of the gas at the compressor outlet assuming an isentropic process, and h2 represents the actual enthalpy of the gas at the compressor outlet.
The isentropic compression efficiency is a dimensionless quantity that ranges from 0 to 1. A value of 1 indicates that the compressor is able to achieve an isentropic process perfectly, while a value of 0 indicates that the compressor is unable to achieve any compression at all.
Compressor isentropic efficiency formula
Isentropic Efficiency of Compressorformula is denoted by the ratio of ideal or isentropic work done to actual work done.
Here, T2’ denotes the exit temperature for ideal or isentropic case.
T1 denotes the temperature at inlet
T2 denotes the temperature at outlet for actual case
Cp is the specific heat, which is considered constant. In terms of compression pressure ratio, the above formula is denoted by:-
Where,
Where Pr is compression pressure ratio, γ is the ratio of specific heats Cp/Cv.
Form above, the Actual exit temperature T2 can be calculated by
Types of Compressors and Their Isentropic Efficiency
A. Reciprocating Compressor Isentropic Efficiency
A reciprocating compressor is a type of compressor that uses a piston to compress the gas. It is commonly used in applications where a high pressure ratio is required, such as in refrigeration and air conditioning systems. The isentropic efficiency of a reciprocating compressor refers to how efficiently it can compress the gas without any heat transfer or pressure losses.
The isentropic efficiency of a reciprocating compressor is influenced by several factors, including the design of the compressor, the type of gas being compressed, and the operating conditions. Generally, reciprocating compressors have high isentropic efficiencies, typically ranging from 70% to 90%.
One of the main advantages of reciprocating compressors is their ability to achieve high compression ratios, which allows for efficient gas compression. However, they also have some limitations, such as higher maintenance requirements and a higher level of noise compared to other types of compressors.
B. Centrifugal Compressor Isentropic Efficiency
Centrifugal compressors are widely used in various industries, including oil and gas, petrochemical, and power generation. They are known for their high flow rates and compact design. The isentropic efficiency of a centrifugal compressor is a measure of how well it can compress the gas without any heat transfer or pressure losses.
Compared to reciprocating compressors, centrifugal compressors typically have lower isentropic efficiencies, ranging from 70% to 85%. This is due to the inherent design characteristics of centrifugal compressors, such as the presence of impellers and diffusers, which introduce some level of inefficiency into the compression process.
Despite their lower isentropic efficiencies, centrifugal compressors offer advantages such as lower maintenance requirements, smoother operation, and the ability to handle a wide range of flow rates. They are often used in applications where a high flow rate is required, such as in large-scale industrial processes.
C. Axial Compressor Isentropic Efficiency
Axial compressors are commonly used in aircraft engines, gas turbines, and turbochargers. They are designed to handle large volumes of gas and achieve high compression ratios. The isentropic efficiency of an axial compressor measures how efficiently it can compress the gas without any heat transfer or pressure losses.
Axial compressors are known for their high isentropic efficiencies, typically ranging from 80% to 90%. This is due to their unique design, which consists of multiple stages of rotating and stationary blades that work together to compress the gas.
The high isentropic efficiency of axial compressors makes them ideal for applications where energy efficiency is crucial, such as in aircraft engines and gas turbines. However, they are also more complex and expensive to manufacture compared to other types of compressors.
D. Screw Compressor Isentropic Efficiency
Screw compressors are widely used in various industries, including refrigeration, air conditioning, and process gas compression. They are known for their compact design, high reliability, and low maintenance requirements. The isentropic efficiency of a screw compressor refers to how efficiently it can compress the gas without any heat transfer or pressure losses.
Screw compressors typically have high isentropic efficiencies, ranging from 80% to 90%. This is due to their unique design, which consists of two interlocking helical rotors that compress the gas as they rotate.
One of the main advantages of screw compressors is their ability to handle a wide range of flow rates and provide a continuous supply of compressed gas. They are also known for their quiet operation and low vibration levels. However, they may not be suitable for applications where a high compression ratio is required.
E. Scroll Compressor Isentropic Efficiency
Scroll compressors are commonly used in residential and commercial air conditioning systems, heat pumps, and refrigeration units. They are known for their compact size, quiet operation, and high reliability. The isentropic efficiency of a scroll compressor measures how efficiently it can compress the gas without any heat transfer or pressure losses.
Scroll compressors typically have high isentropic efficiencies, ranging from 70% to 80%. This is due to their unique design, which consists of two interleaving spiral-shaped scrolls that compress the gas as they orbit.
One of the main advantages of scroll compressors is their ability to provide a smooth and continuous flow of compressed gas, resulting in improved energy efficiency. They are also known for their low maintenance requirements and long service life. However, they may not be suitable for applications where a high compression ratio is required.
In conclusion, different types of compressors have varying isentropic efficiencies, which are influenced by factors such as design, gas type, and operating conditions. Understanding the isentropic efficiency of a compressor is crucial for selecting the most suitable compressor for a specific application, taking into account factors such as energy efficiency, flow rate requirements, and maintenance considerations.
Isentropic Efficiency in Different Systems
A. Gas Turbine Compressor Isentropic Efficiency
Gas turbine compressors play a crucial role in the operation of gas turbines, which are widely used in power generation and aircraft propulsion systems. The isentropic efficiency of a gas turbine compressor is a key parameter that determines its performance and energy efficiency.
The isentropic efficiency for a gas turbine is defined by following expression:
ηT=Real Turbine Work/ Isentropic Turbine Work
Isentropic efficiency is a measure of how well a compressor can compress the incoming air without any losses due to heat transfer or friction. It represents the ratio of the actual work done by the compressor to the ideal work that would be required in an isentropic (reversible adiabatic) process. In simple terms, it quantifies how close the compressor comes to an ideal, frictionless compression process.
Gas turbine compressors can be either centrifugal or axial flow compressors. Centrifugal compressors use centrifugal force to accelerate the air and then convert the kinetic energy into pressure energy. On the other hand, axial flow compressors use a series of rotating and stationary blades to compress the air in a continuous flow.
The isentropic efficiency of a gas turbine compressor depends on various factors, including the design of the compressor, the number of compressor stages, and the operating conditions. Higher isentropic efficiency indicates a more efficient compressor, as it requires less work to achieve the desired pressure ratio.
B. Refrigeration Compressor Isentropic Efficiency
Refrigeration systems are widely used in various applications, including air conditioning, food preservation, and industrial processes. The compressor is a vital component of a refrigeration system, responsible for compressing the refrigerant and increasing its pressure.
The isentropic efficiency of a refrigeration compressor is an important parameter that affects the overall performance and energy efficiency of the system. It measures the ability of the compressor to compress the refrigerant without any losses in the form of heat transfer or pressure drop.
Refrigeration compressors can be classified into different types, such as reciprocating, rotary, and scroll compressors. Each type has its own advantages and disadvantages in terms of efficiency, cost, and noise level.
To improve the isentropic efficiency of a refrigeration compressor, manufacturers focus on optimizing the compressor design, reducing internal losses, and minimizing leakage. Additionally, proper maintenance and regular cleaning of the compressor can help maintain its efficiency over time.
C. Heat Pump Compressor Isentropic Efficiency
Heat pumps are devices that transfer heat from a lower temperature source to a higher temperature sink, using mechanical work. The compressor in a heat pump plays a crucial role in raising the temperature of the working fluid and increasing its pressure.
Performance of a heat pump is defined by:
Where,
V= volume in cum/m
z= Compresibility facotor, 1 for air
ρ= density of air
R= universal gas constant, 286 J/(kg*К) for air
γ = ratio of specific heat, 1.4 for air
Calculating, by putting the above values we get
nw = 175.5 KW
Thus, the isentropic efficiency of compression is nw/na = 17.5./200 = 0.88 or 88%
Comparing the efficiencies of reciprocating compressors, centrifugal compressors and axial flow compressors, the later has the best efficiencies and ranges above 90%. This is mostly because of of minimum mechanical and aerodynamic losses it encounters as the gas traverses the path thoruch the compressing device.
A typical axial compressor is shown below. it has got alternate rotaing vanes and static airfoils, which converts the kinetic energy to pressure.
Axial flow compressors are generally employed for high flow rates primarily in jet engines, as turbines and some process apllications. For a given flow however, compared to a centrifugal machine which has a raidal flow componet, the axial flow compressors have lower wetted area and loe sealing requriement contributing to its higher isentropic efficiency.
Compressor Polytropic Efficiency vs Isentropic Efficiency
A. Understanding Compressor Polytropic Efficiency
When it comes to understanding the efficiency of a compressor, two important terms often come up: polytropic efficiency and isentropic efficiency. In this section, we will focus on understanding compressor polytropic efficiency.
What is Polytropic Efficiency?
Polytropic efficiency is a measure of how effectively a compressor can compress a gas. It takes into account the energy losses that occur during the compression process, such as heat transfer and friction. Unlike isentropic efficiency, which assumes an ideal, reversible process with no energy losses, polytropic efficiency considers the real-world conditions and factors that affect the compression process.
How is Polytropic Efficiency Calculated?
The calculation of polytropic efficiency involves comparing the actual work done by the compressor to the work that would be done in an ideal, isentropic process. The formula for polytropic efficiency is as follows:
The actual work done by the compressor can be determined by measuring the power input to the compressor motor, while the isentropic work can be calculated using the ideal gas law and the pressure ratio across the compressor.
B. Comparison Between Polytropic and Isentropic Efficiency
Now that we have a basic understanding of polytropic efficiency, let’s compare it to isentropic efficiency.
Isentropic Efficiency: The Ideal Case
Isentropic efficiency is a measure of how close a compressor comes to achieving an ideal, reversible compression process. In an isentropic process, there are no energy losses, and the entropy of the gas remains constant. This idealized process assumes that the compression is adiabatic (no heat transfer) and reversible (no friction or other losses).
Polytropic Efficiency: Accounting for Real-World Factors
Unlike isentropic efficiency, polytropic efficiency takes into account the energy losses that occur during the compression process. These losses can be caused by factors such as heat transfer between the gas and the compressor walls, friction in the compressor components, and non-ideal gas behavior. Polytropic efficiency provides a more realistic measure of how efficiently a compressor is performing under real-world conditions.
Comparing the Two Efficiencies
In general, isentropic efficiency is higher than polytropic efficiency because it assumes an ideal, lossless process. However, in real-world applications, achieving isentropic efficiency is not always possible due to the presence of energy losses. Polytropic efficiency gives a more accurate representation of the actual performance of a compressor.
It’s important to note that both polytropic and isentropic efficiency are valuable metrics for evaluating compressor performance. While isentropic efficiency provides an ideal benchmark, polytropic efficiency accounts for the real-world factors that affect compressor operation.
In summary, polytropic efficiency and isentropic efficiency are two measures used to evaluate the performance of compressors. Polytropic efficiency considers the energy losses that occur during compression, providing a more realistic measure of compressor performance. Isentropic efficiency, on the other hand, assumes an ideal, lossless process. Both metrics have their merits and are useful in different contexts.
Calculating Compressor Isentropic Efficiency
A. How to Calculate Compressor Isentropic Efficiency
Compressor isentropic efficiency is a crucial parameter that determines the performance of a compressor. It measures how effectively a compressor can compress a gas without any heat transfer or pressure losses. To calculate the compressor isentropic efficiency, you need to know the inlet and outlet conditions of the compressor, such as the pressure and temperature.
The formula to calculate compressor isentropic efficiency is as follows:
Isentropic Efficiency = (h1 – h2s) / (h1 – h2)
Where: – h1 is the enthalpy at the compressor inlet – h2s is the isentropic enthalpy at the compressor outlet – h2 is the actual enthalpy at the compressor outlet
The enthalpy values can be obtained from thermodynamic tables or through calculations using the specific heat capacity of the gas being compressed.
B. Practical Examples of Compressor Isentropic Efficiency Calculation
Let’s consider a practical example to understand how to calculate compressor isentropic efficiency. Suppose we have a centrifugal compressor that compresses air from an inlet pressure of 1 bar to an outlet pressure of 5 bar. The inlet temperature is 25°C, and the outlet temperature is 100°C. We want to determine the isentropic efficiency of the compressor.
First, we need to find the enthalpy values at the compressor inlet and outlet. Using the specific heat capacity of air (Cp), we can calculate the enthalpy as follows:
h1 = Cp * (T1 – Tref) h2 = Cp * (T2 – Tref)
Where: – T1 is the temperature at the compressor inlet – T2 is the temperature at the compressor outlet – Tref is the reference temperature (usually taken as 0°C)
Let’s assume Cp for air is 1 kJ/kg·K. Plugging in the values, we get:
In this example, the isentropic efficiency of the centrifugal compressor is approximately 43.24%. This means that the compressor is able to achieve 43.24% of the ideal isentropic compression process, considering the given inlet and outlet conditions.
By calculating the compressor isentropic efficiency, engineers can evaluate the performance of a compressor and compare it with other compressors. This information is vital for selecting the right compressor for a specific application and optimizing energy efficiency in various industries, including refrigeration, air conditioning, and power generation.
Improving Compressor Isentropic Efficiency
A. Performance Optimization for Better Efficiency
To improve the isentropic efficiency of a compressor, various performance optimization techniques can be employed. These techniques aim to enhance the efficiency of the compression process, resulting in reduced energy consumption and improved overall performance. Here are some key strategies for optimizing compressor efficiency:
Proper Sizing and Selection: Ensuring that the compressor is properly sized and selected for the specific application is crucial. This involves considering factors such as the required flow rate, pressure ratio, and operating conditions. Choosing the right compressor type (centrifugal or axial) and the appropriate number of stages can significantly impact efficiency.
Optimal Pressure Ratio: The pressure ratio, defined as the ratio of the discharge pressure to the suction pressure, plays a vital role in compressor efficiency. By carefully selecting the pressure ratio, it is possible to achieve higher isentropic efficiency. However, it is important to strike a balance, as excessively high pressure ratios can lead to increased mechanical losses and reduced efficiency.
Enhanced Heat Transfer:Improving heat transfer within the compressor can help increase efficiency. This can be achieved through the use of advanced cooling techniques, such as intercooling and aftercooling. These techniques involve removing heat from the compressed air between stages, reducing the temperature and improving overall efficiency.
Reduced Internal Leakage: Minimizing internal leakage within the compressor is crucial for improving efficiency. This can be achieved through proper sealing and maintenance of the compressor components. Regular inspections and maintenance can help identify and address any leakage issues, ensuring optimal performance.
Optimized Operating Conditions: Operating the compressor at its optimal conditions can significantly improve efficiency. This includes maintaining the compressor within its recommended speed range, avoiding excessive pressure drops, and ensuring proper lubrication. Additionally, controlling the inlet air temperature and humidity can help optimize performance.
B. Advanced Design and Technology for Efficiency Improvement
Advancements in compressor design and technology have paved the way for significant improvements in isentropic efficiency. Here are some key areas where advanced design and technology have contributed to efficiency improvement:
Improved Aerodynamics:Modern compressors incorporate advanced aerodynamic designs that optimize airflow and reduce losses. This includes the use of advanced blade profiles, optimized impeller and diffuser geometries, and the incorporation of computational fluid dynamics (CFD) simulations. These advancements help minimize flow separation, reduce pressure losses, and enhance overall efficiency.
Efficient Mechanical Systems:The mechanical systems within a compressor, such as bearings and seals, play a crucial role in overall efficiency. Advanced bearing technologies, such as magnetic bearings and oil-free designs, minimize friction losses and improve efficiency. Similarly, advanced sealing techniques help reduce internal leakage and improve overall performance.
Variable Geometry: Compressors with variable geometry offer enhanced efficiency by adjusting the compressor’s internal geometry based on operating conditions. This allows for better matching of the compressor’s performance to the system requirements, resulting in improved efficiency across a wider range of operating conditions.
Advanced Materials:The use of advanced materials, such as lightweight alloys and composites, in compressor construction helps reduce weight and improve efficiency. These materials offer better strength-to-weight ratios, reducing the energy required to drive the compressor and improving overall efficiency.
Smart Control Systems:The integration of smart control systems and advanced algorithms allows for real-time monitoring and optimization of compressor performance. These systems can adjust operating parameters, such as speed and pressure, to maximize efficiency based on the current operating conditions. This results in improved overall efficiency and reduced energy consumption.
C. Maintenance and Its Impact on Isentropic Efficiency
Regular maintenance plays a crucial role in maintaining and improving the isentropic efficiency of a compressor. Neglecting maintenance can lead to decreased efficiency, increased energy consumption, and potential system failures. Here are some key maintenance practices and their impact on isentropic efficiency:
Regular Inspection and Cleaning: Regularly inspecting and cleaning the compressor components, such as the impeller, diffuser, and inlet filters, is essential for optimal performance. Accumulated dirt, debris, and fouling can restrict airflow, increase pressure losses, and reduce efficiency. Cleaning these components ensures smooth airflow and optimal performance.
Proper Lubrication:Adequate lubrication of the compressor’s moving parts is crucial for reducing friction losses and maintaining efficiency. Regularly checking and replenishing lubricants, as per the manufacturer’s recommendations, helps ensure smooth operation and optimal efficiency.
Seal Maintenance:Proper maintenance of seals, gaskets, and O-rings is essential for minimizing internal leakage and improving efficiency. Regularly inspecting and replacing worn-out seals helps maintain proper compression and prevents energy losses due to leakage.
Vibration Analysis: Monitoring and analyzing compressor vibrations can help identify potential issues and prevent failures. Excessive vibrations can indicate misalignment, worn-out bearings, or other mechanical problems that can negatively impact efficiency. Timely detection and correction of these issues can help maintain optimal efficiency.
Performance Monitoring: Implementing a comprehensive performance monitoring system allows for real-time tracking of key performance parameters, such as pressure, temperature, and power consumption. Any deviations from expected values can be quickly identified, allowing for timely corrective actions to maintain optimal efficiency.
By implementing performance optimization techniques, leveraging advanced design and technology, and prioritizing regular maintenance, it is possible to significantly improve the isentropic efficiency of compressors. These improvements not only reduce energy consumption but also contribute to cost savings and environmental sustainability.
The Role of Isentropic Efficiency in Renewable Energy Systems
A. Isentropic Efficiency in Turbine and Compressor Systems
In the realm of renewable energy systems, isentropic efficiency plays a crucial role in optimizing the performance of turbine and compressor systems. These systems are integral components of various renewable energy technologies such as wind turbines, hydroelectric power plants, and solar thermal power plants. Understanding the concept of isentropic efficiency is essential for maximizing energy conversion and minimizing energy losses in these systems.
Isentropic Efficiency in Compressor Systems
Compressor systems are responsible for increasing the pressure of a fluid, such as air or gas, in order to facilitate various processes in renewable energy systems. Isentropic efficiency in compressor systems refers to the ability of the compressor to achieve the highest possible pressure increase with the least amount of energy input.
When a compressor operates under ideal conditions, it undergoes an isentropic process, which is a thermodynamic process that occurs without any heat transfer or entropy change. In this ideal scenario, the compressor achieves maximum efficiency, known as the isentropic efficiency. However, in real-world scenarios, compressors experience various losses, such as mechanical friction, heat transfer, and fluid leakage, which reduce their efficiency.
Comparing Isentropic Efficiency in Different Compressor Types
Different types of compressors, such as centrifugal and axial compressors, exhibit varying levels of isentropic efficiency. Centrifugal compressors, for example, are known for their high isentropic efficiency, making them ideal for applications that require high-pressure ratios. On the other hand, axial compressors are more suitable for applications that require a large volume flow rate.
The isentropic efficiency of a compressor is typically influenced by factors such as the pressure ratio, the number of compressor stages, and the design and operation of the compressor. By carefully considering these factors, engineers can optimize the isentropic efficiency of compressor systems in renewable energy applications.
B. Multi objective Optimization in Renewable Energy Systems
In the pursuit of enhancing the efficiency and performance of renewable energy systems, multiobjective optimization techniques play a significant role. These techniques aim to simultaneously optimize multiple objectives, such as maximizing energy conversion efficiency, minimizing energy losses, and reducing environmental impact.
Balancing Efficiency and Environmental Impact
One of the primary objectives of multi objective optimization in renewable energy systems is to strike a balance between energy efficiency and environmental impact. While it is crucial to maximize the isentropic efficiency of compressor systems to achieve optimal energy conversion, it is equally important to minimize the environmental footprint associated with these systems.
By employing advanced computational algorithms and simulation tools, engineers can explore various design and operational parameters to identify the optimal configuration that achieves the desired balance between efficiency and environmental impact. This approach ensures that renewable energy systems not only perform optimally but also contribute to sustainable development.
Considering Exergy Analysis in Multi objective Optimization
Exergy analysis is another valuable tool in multi objective optimization for renewable energy systems. Exergy is a measure of the quality of energy and represents the maximum useful work that can be obtained from a system. By incorporating exergy analysis into the optimization process, engineers can identify areas of energy loss and inefficiency within compressor systems.
Through exergy analysis, engineers can pinpoint specific components or processes that contribute to energy losses and devise strategies to mitigate them. This approach enables the identification of opportunities for improving the isentropic efficiency of compressor systems, ultimately leading to enhanced overall system performance.
In conclusion, isentropic efficiency plays a vital role in optimizing the performance of turbine and compressor systems in renewable energy applications. By understanding and improving the isentropic efficiency of compressor systems, engineers can enhance energy conversion efficiency and minimize energy losses. Additionally, multi objective optimization techniques, coupled with exergy analysis, enable engineers to strike a balance between efficiency and environmental impact, ensuring the sustainable operation of renewable energy systems. Conclusion
In conclusion, the compressor isentropic efficiency is a crucial parameter that determines the performance of a compressor. It measures how effectively a compressor can convert the input power into useful work, without any losses. A higher isentropic efficiency indicates a more efficient compressor, as it can compress the gas with less energy consumption and minimal heat generation. On the other hand, a lower isentropic efficiency implies that the compressor is less efficient and may require more power to achieve the desired compression. It is important to consider the isentropic efficiency when selecting a compressor for various applications, as it directly impacts the energy consumption and overall performance. By understanding and optimizing the isentropic efficiency, engineers and designers can improve the efficiency and reliability of compressors, leading to cost savings and reduced environmental impact.
Frequently Asked Questions
1. What is the isentropic efficiency of a compressor?
Isentropic efficiency of a compressor is a measure of how much the actual performance of the compressor deviates from the ideal or isentropic process. It is calculated as the ratio of the isentropic work to the actual work done by the compressor.
2. How to calculate compressor isentropic efficiency?
The isentropic efficiency of a compressor can be calculated using the formula: η_isentropic = (h2s – h1) / (h2 – h1), where h2s is the isentropic enthalpy at the exit, h1 is the enthalpy at the inlet, and h2 is the actual enthalpy at the exit.
3. What is the difference between compressor polytropic efficiency and isentropic efficiency?
Polytropic efficiency is a measure of the work done during a polytropic process, which is a process that involves heat transfer. On the other hand, isentropic efficiency is a measure of the work done during an isentropic process, which is an idealized process that assumes no heat transfer.
4. What is the typical isentropic efficiency of a compressor?
The typical isentropic efficiency of a compressor varies depending on the type of compressor. For example, reciprocating compressors typically have isentropic efficiencies around 70-75%, while centrifugal compressors can have isentropic efficiencies as high as 85-90%.
5. How does the isentropic efficiency of a compressor affect its performance?
The isentropic efficiency of a compressor directly affects its performance. A higher isentropic efficiency means that the compressor requires less work to compress a given amount of gas, which makes it more energy efficient.
6. What factors can affect the isentropic efficiency of a compressor?
Several factors can affect the isentropic efficiency of a compressor, including the design of the compressor, the operating conditions, the type of gas being compressed, and the maintenance of the compressor.
7. How can the isentropic efficiency of a compressor be improved?
The isentropic efficiency of a compressor can be improved through various methods, such as optimizing the compressor design, maintaining the compressor properly, and operating the compressor at optimal conditions.
8. How does the isentropic efficiency of a compressor relate to the thermodynamic efficiency?
The isentropic efficiency of a compressor is a measure of how closely the compressor’s performance matches the ideal isentropic process. The thermodynamic efficiency, on the other hand, is a measure of how much of the input energy is converted into useful work. Therefore, a higher isentropic efficiency generally leads to a higher thermodynamic efficiency.
9. How does the isentropic efficiency of a compressor affect the refrigeration cycle?
The isentropic efficiency of the compressor affects the performance of the refrigeration cycle. A higher isentropic efficiency means that the compressor can compress the refrigerant with less work, which improves the efficiency of the refrigeration cycle.
10. What is the role of entropy in the isentropic efficiency of a compressor?
Entropy is a measure of the disorder or randomness in a system. In an isentropic process, the entropy remains constant. Therefore, if the compressor’s process is not isentropic and entropy increases, this indicates energy losses, which reduces the isentropic efficiency of the compressor.
In this article “Friction factor for turbulent flow” and friction factor for turbulent flow related several information will be discuss. The common method is to determine friction factor for turbulent flow is Moody diagram.
The friction factor is a physical parameter which is a dimensionless. The turbulent flow for a particular given type field is constant. The friction factor for turbulent flow only depends on the geometry of the channel and Reynolds number. The flow is called turbulent when Reynolds number is more than 3500.
What is the friction factor for turbulent flow?
Maximum system of the fluid in the nuclear facilities is work with the flow type of turbulent flow. The resistance of this flow obey the equation of Darcy – Weisbach.
The friction of the turbulent flow is measurement of the shear stress which is applied in the wall of a rod or pipe during the flow of turbulent. The flow of turbulent is obeying the equation of Darcy – Weisbach which is directly proportional to square of mean velocity of the flowing fluid in a certain area.
Turbulent flow:-
When the value of Reynolds number is more than 3500 this type of flow called turbulent flow.
Mathematical analysis of the turbulent flow is not too easy.
Velocity of the turbulent flow is too high.
Irregular movement is appearing in fluids which are flow in a motion in turbulent flow.
Average motion is appearing in which side fluid is flowing.
Turbulent flow in general very common type of flow.
The velocity profile of the flow turbulent in a certain area is quickly drops when it comes to the wall of the pipe or rod.
The velocity profile of the flow turbulent in a certain area is clearly flat when it comes to the center section of the rod or pipe.
Image – Turbulent flow in flowing of a river; Image Credit – Wikimedia Commons
Friction factor for turbulent flow formula:
The Colebrook–White equation is define as f for the Darcy friction factor, the function of for Reynolds number as Re, pipe relative roughness express as, ε / Dh for both smooth pipes and rough pipes.
The friction factor for turbulent flow formula is,
or,
Where,
Dh (m , ft) = Hydraulic diameter for filling the fluid in circular conduits
Dh = D= Inside diameter of the area from where flow of turbulent is flowing
Rh (m , ft) = Hydraulic radius for filling the fluid in circular conduits
Rh = D/4 = Inside diameter of the area from where flow of turbulent is flowing/4
The equation of Colebrook is solved by numerically for its implicit nature. Now a day Lambert W function is also use to obtain outspoken reformulation the equation of Colebrook.
or,
We will get,
px = ax + b
Expanded forms:-
Additional mathematical form of the equation of Colebrook is,
Where,
1.7384…. = 2 log (2 * 3.7) = 2 log (7.4)
18.574 = 2.51 * 3.7 * 2
And,
Or,
Where,
1.1364…. = 1.7384… = – 2 log (2) = 2 log
(7.4) – 2 log (2) = 2 log (3.7)
9.287 = 18.574/2 = 2.51 * 3.7
How to calculate friction factor for turbulent flow?
The process of calculating friction factor for turbulent flow is given below,
At first we need to determine the value of Reynolds number for the turbulent flow using this formula,
ρ x V x D x μ
In the next step relative roughness should be calculated using k/D formula which value to under 0.01
In the final step use the Moody formula for the roughness with the help of Reynolds number,
Friction factor for turbulent flow in pipe:
The range friction factor for turbulent flow in pipe is
For smooth pipe,
0.04 At Re 4000 to 1.01 at Re 3 x 106
For rough pipe,
0.045 At Re 4000 to 0.03 at Re 3 x 106
Friction factor for turbulent flow in smooth pipe:
Friction factor for turbulent flow in smooth pipe can be explained by the help of Blasius correlation. Blasius correlation is the simplest form of determine the Darcy friction factor.
Blasius correlation is only applicable for turbulent flow in smooth pipes it is not applicable for turbulent flow in uneven pipes. The value of 100000 of Reynolds number Blasius correlation is valid. In some cases of turbulent flow in uneven pipes is applied only because of its simplicity.
Mathematical equation of Blasius correlation turbulent flow in uneven pipes is given below,
After that the equation is corrected and express as,
With,
Where,
f is a function for the,
D = Pipe diameter express as meter, feet
R = Curve radius express as meter, feet
H = Helicoidal pitch express as meter, feet
Re = Reynolds number which is dimensionless
Reynolds number valid for,
0 < H/D < 25.4
Friction factor for turbulent flow in rough pipe:
The Darcy friction factor for turbulent flow in rough pipe means value of Reynolds number is more than 4000 is expressed by Colebrook – White equation.
or,
Where,
Dh (m , ft) = Hydraulic diameter for filling the fluid in circular conduits
Dh = D = Inside diameter of the area from where flow of turbulent is flowing
Rh (m , ft)= Hydraulic radius for filling the fluid in circular conduits
Rh = D/4 = Inside diameter of the area from where flow of turbulent is flowing/4
The equation of Colebrook is solved by numerically for its implicit nature. Now a day Lambert W function is also use to obtain outspoken reformulation the equation of Colebrook.
or,
We will get,
px = ax + b
Expanded forms:-
Additional mathematical form of the equation of Colebrook is,
Where,
1.7384…. = 2 log (2 * 3.7) = 2 log (7.4)
18.574 = 2.51 * 3.7 * 2
And,
Or,
Where,
1.1364…. = 1.7384… = – 2 log (2) = 2 log
(7.4) – 2 log (2) = 2 log (3.7)
9.287 = 18.574/2 = 2.51 * 3.7
Friction factors for turbulent flow in curved pipes:
In order to calculate the pressure drop with in a coil or pipe the friction factor should be calculated at first.
Friction factors for turbulent flow in curved pipes is discuss below,
D = Internal diameter of the coil or pipe
R = Darius of the coil or pipe helix
De = Dean Number
Rec = Transitional Reynolds number
fc = Friction factor of the coil or pipe which smooth
frough = Friction factor for a rough coil or pipe
fsmooth = Friction factor for a smooth coil or pipe
When a single phase flow is appear in a pipe or coil which shaped is curved a secondary flow pattern is introduce in the coil or pipe, in this time friction factor and fluid behaviour start to changes.
As the effect of stabilization of fluid flow the output is comes increases the Reynolds number at that point when flow is enter to the coil or pipe the transition flow form laminar flow to the flow of turbulent.
This condition mathematical form is given below,
To calculate the friction factor in a pipe or coil the Dean number is needed,
After this we easily can determine the friction factor for a smooth coil or pipe.
For,
De < 11.6
fc = 64/Re
For,
11.6 < De < 200
For, De > 2000
For calculation of totally turbulent flows determine the friction factor for a smooth coil or pipe using this equation,
The range is,
Moody diagram friction factor for turbulent flow:
In the flow of turbulent the relation between Reynolds number represent as Re, friction factor represent as fD, and relative roughness represent as ∈/D is complicated.
The expression for Moody diagram friction factor for turbulent flow is,
Image – Darcy Friction factor for Re between 10 and 10E8 for values of relative roughness; Image Credit – Wikimedia Commons
Frequent Asked Questions:-
Question:-Write about theDarcy friction factor chart.
Solution:-Darcy friction factor chart is combination of four physical parameters such as, pressure loss coefficient, Reynolds number, and relative roughness of the coil or pipe and diameter ratio of the coil or pipe.
Darcy friction factor chart is dimensionless physical factor with the help of Darcy – Weisbach equation can be written as,
Pressure drop can be calculate as,
Or,
Image – Equal-friction chart for air in metal duct (ε = 0.05 mm); Image Credit – Wikimedia Commons
The expression for Darcy friction factor for laminar flow is,
fD = 64/Re
In the flow of turbulent the relation between Reynolds number represent as Re, friction factor represent as fD, and relative roughness represent as ∈/D is complicated.
The expression for Darcy friction factor for turbulent flow is,
In this article “Thermal insulation examples” will be discuss with its related several facts. Thermal insulation examples are not suitable for transferring the heat from one circumstance to another circumstance.
13+ Thermal Insulation Examples with several facts are listed below,
In our surroundings lots of insulators are present in solid state. The examples solid state insulators are,
Glass:-
The solid insulator example is glass. From the definition of thermal insulation we can get an idea that the heat cannot from one space to another space. The electrons which are present in the glass not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Ordinary glass is appropriate example of solid thermal insulator just one problem with the glass is it is brittle.
Image – Blue Crystal Cube made with glass; Image Credit – pixabay
Asbestos:-
The solid insulator example is Asbestos. The electrons which are present in the asbestos not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Bakelite is a material which is very strong in mechanically.
Bakelite is a polymer which made with monomers of formaldehyde and phenol.
Another solid insulator example is Bakelite. The electrons which are present in the Bakelite not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Another example of thermal insulator is Mica. The electrons which are present in the mica not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
In high temperature mechanically the mica became week.
High dielectric strength is about 30 kV/mm.
Rubber:-
Rubber is the insulator of thermal example. The electrons which are present in the rubber not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Rubber has tensile strength.
Tear resistance
Elongation
Abrasion resistance
Specific gravity
Tensile modulus
Hardness
Paper:-
The electrical property of the paper is adequately good.
Paper is made from wood pulp after that manila fibers are beaten and finally rolled into sheets.
Another solid insulator example is Paper. The electrons which are present in the paper not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Papers have dielectric strength near about 4 to 10 kV/mm.
Hygroscopic
The application of paper is wallpaper, filter paper, writing, toilet tissue, security paper and laminated worktops.
Silk or cotton:-
Elasticity
Light weight
Easy to use
Initial cost is low
Available
Silk or cottons have dielectric strength
Thermal insulator another example is Silk or cotton. The electrons which are present in the silk or cottons not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Silk or cottons can be used in various ways such as cooking oils, making of clothes, towels, sheets, currency paper, animal feed biofuels and many more.
Another solid insulator example is Ceramics. The electrons which are present in the ceramics not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Oxidation resistant
Prone to thermal shock
Ceramics are both thermal insulator and electrical insulator
Ceramics uses in cutting tools, in space industry.
Ceramics works as both thermal insulator and electrical insulator.
Dry air:-
Dry air is thermal insulator. The electrons which are present in the Bakelite not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Dry air not easily affected by heat
Exerts pressure
Can be compressed
Affected by altitude
Economical
Eco friendly
Light weight
Easy to use
Initial cost is low
Available
Wood:-
Wood has good amount of strength.
Wood is another example for thermal insulator. The electrons which are present in the wood not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Wood has both two characteristics such as tension and compression
Wood can be used in various fields such as packing, weapons, tools, paper, artwork, constructions and many more.
Diamond:-
Diamond is not brittle type
Another example is Diamond of thermal insulator. The electrons which are present in the diamond not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Diamonds have thermal conductivity
Combustibility
Compressive strength
Tear resistance
Plastic:-
Plastic is water resistant
Plastic is shock resistant
Another example is plastic of thermal insulator, the electrons which are present in the plastic not able to carry heat just because of the electrons are participating chemical bonds for this reason the electrons are could not get free time to conducting heat and heat cannot flow from circumference to another circumference.
Styrofoam is another example of thermal insulator. Thermal insulator material means from where heat cannot flow one area to another area among them Styrofoam is. The electrons of the Styrofoam could not carry electrons just because of the electrons which are present in the Styrofoam they are engage to make chemical bonds to each other for this reasons the electrons are not free to take part in the conduction of heat, for this reason heat could not flow through Styrofoam material.
In this article the “Vapor compression refrigeration cycle” topic and vapor compression refrigeration cycle related facts are going to summarize to briefly that a clear concept can we get from it effortlessly.
In vapor compression refrigeration cycle a refrigerant which is stays in fluid is used within a system which stays in as closed and proposed to going in four methods such as compression, then cooling with condensation, after that that expansion and lastly heating with evaporation.
What is vapor compression refrigeration cycle?
In the system of air conditioning the vapor compression refrigeration cycle is commonly used. The fluid which is works as medium in the vapor compression refrigeration cycle is states in vapor state.
Vapor compression refrigeration cycle can be explain in this way lowering the inside temperature of a closed system than the normal temperature and helps to reject the excess amount of heat from the area of the closed system and after doing this process finally transfer the excess amount of heat in environment.
Image – A simple stylized diagram of a heat pumps’s Vapor compression refrigeration cycle 1. Condenser; 2. Expansion valve; 3. Evaporator; 4. Compressor ; Image Credit – Wikipedia
The compression refrigeration cycle of vapor is used in many purposes like, for domestic purposes, commercial purposes, industrial services and automobile sectors.
In vapor compression cycle the refrigerants which are used commonly they are, NH_3, R – 12, and R- 11. In the vapor compression cycle of a refrigeration system which components are used they are listed below,
Refrigerant compressor
Liquid compressor
Liquid receiver
Evaporator valve
Expansion valve These Evaporator valve and Expansion valve both are called as refrigerant control valve.
Vapor compression refrigeration cycle diagram:
The Vapor compression cycle contain liquid refrigerant which act as a medium of the vapor compression refrigeration cycle. The refrigerant changes state of phase during the process for two times.
A simple type of vapor compression refrigeration cycle diagram if we observe then can found main four components.
The refrigerant when it is vapour state that time it carry lower temperature and lower pressure than the regular one and enters to the compressor of the vapor compression refrigeration cycle from the evaporator of the system. After enter to the evaporator the vapour became carry higher temperature as well as higher pressure. The refrigerant vapor of the system which carries higher temperature and higher pressure is entering to the condenser with the help of discharge valve.
Condenser:-
In the condenser when the refrigerant vapors of the system which carries higher temperature and higher pressure is enter that time the vapor of the refrigerant became condensed and cooled for the coils are present in the pipe inside the air conditioning system.
When the refrigerant is go through the condenser that time latent heat is emitted in the surrounding of the condensing medium which consider as water or air.
The liquid refrigerant which is in condensed state of phase is stored in a container from the condenser. The container where liquid refrigerant is stores is known as receiver. After go through the condenser liquid refrigerant is comes to the evaporator by the evaporator valve.
Expansion valve:-
Another name for the expansion valve is throttle valve. The function of expansion valve is to give permission to liquid refrigerant go through with high temperature and high pressure where the liquid refrigerant could reduce its pressure and temperature.
Evaporator:-
In the evaporator of any cooling system contain pipes or coils where the liquid refrigerant has low temperature and low pressure. In evaporator liquid refrigerant is evaporated and transfer into vapor refrigerant where the temperature and pressure is both are stays in low.
In the beginning of the process the liquid refrigerant change its state of phase liquid to vapor and after that the liquid refrigerant change state of phase from vapor state to liquid.
Vapor compression refrigeration cycle T-S and P-V diagram:
For any cooling system the cycle process of vapor compression can be figure out with the help of Pressure – Volume diagram and Temperature –Specific entropy diagram.
Image – Pressure – Volume diagram; Image Credit – Wikipedia
Temperature –Specific entropy diagram
Image – Temperature –Specific entropy diagram; Image Credit – Wikipedia
If we observe the Pressure – Volume diagram and Temperature –Specific entropy diagram then can figure out refrigerant vapor is entr to the compressor in dry saturation situation. After that the saturated and dry refrigerant vapor is enter to the compressor of the refrigeration system at the point 1 where the vapor refrigeration is compress in isentropically process. Now the vapor refrigerant is go from 1 point to 2 point at this particular time pressure is increases from pressure of evaporator to pressure of condenser.
Now at the point 2 saturated refrigerant vapor is enter to the condenser. In condenser heat is emitted at the fixed pressure. For emission of heat normally temperature of the system is decreases and at the same time change of phase is happened. Latent heat is rejected and reaches to liquid refrigerant at saturation temperature at the point of 3.
Then the liquid refrigerant is passes by the expansion valve. In this situation liquid refrigerant decreases its pressure and throttle upbringing the enthalpy constant.
How vapour compression refrigeration system works?
The Vapor compression cycle is a method which is most commonly used in various fields because its cost of charge is very low and the construction of the vapor compression cycle is quite easy to establish.
The cycle process of vapor compression in refrigeration system is working based on reverse Rankine cycle. The Vapor compression cycle process is proceeding in four steps. They are listed below,
Image – The cycle process of vapor compression in refrigeration system; Image Credit – Wikipedia
In this below section the four steps are discusses,
Compression (Reversible adiabatic compression):
The refrigerant of vapor compression cycle at low temperature and pressure stretched from evaporator to compressor where the refrigerant is compressed isentropically. The pressure is rises from p1 to p2 and temperature is rises from T1 to T 2. The total workdone per kg of refrigerant happened during isentropic compression can be express as,
w = h2 – h1
Where,
h1 = Amount of enthalpy of vapor compression cycle in temperature T1, at the step of suction of compressor
h2 = Amount of enthalpy of vapor compression cycle in temperature T2, at the step of discharge of compressor.
Condensation (Constant pressure heat rejection):
The refrigerant of vapor compression cycle is passes through from compressor to condenser at high temperature and pressure. At constant pressure and temperature the refrigerant is completely condensed. The refrigerant changes its state from vapor to liquid.
Throttling (Reversible adiabatic expansion):
At high temperature and high pressure the refrigerant of vapor compression cycle is expanded through the process of throttling. That time the expansion valve is stays in low temperature and pressure. A little amount of liquid refrigerant is evaporating by the help of expansion valve and a huge amount of liquid refrigerant is vaporised by the help of evaporator.
Evaporation (Constant pressure heat addition):
The refrigerant mixture of vapor and liquid is completely evaporated and changed itself into vapor refrigerant. During this evaporation process the refrigerant is absorb latent heat which state is cool. The amount of latent heat absorption by the refrigerant in vapor cycle is known as Refrigerating effect.
Performance of vapour compression cycle in the refrigeration system:
The vapour compression cycle in the refrigeration system is working at evaporator in the law of Steady Flow Energy Equation,
h4 + Qe = h1 + 0
Qe = h1 – h4
The vapour compression cycle in the refrigeration system is working at condenser in the law of Steady Flow Energy Equation,
h2 + Qc = h3 + 0
Qc = h3 – h2
The vapour compression cycle in the refrigeration system is working at expansion valve in the law of Steady Flow Energy Equation,
h3 + Q = h4 + W
We know, value of Q and W is 0
So, we can write,
h3 = h4
Performance of vapour compression cycle in the refrigeration system is,
Vapor compression refrigeration cycle steps:
Vapor absorption cycle process is done by four steps.
In first of the Vapor absorption cycle process compression process is done. In this process vapor stays at very low pressure and temperature. The vapor is enters to the compressor when it is compressed subsequently and isentropically. After this both temperature and pressure are increases.
Condensation process:
After completing the process in compressor vapor enter to condenser. The vapor is condensed in the high pressure and goes to the receiver tank.
Expansion process:
After completing the process in condenser vapour enter to expansion valve from receiver tank. The throttling process is done in the low pressure and low temperature.
Vaporization process:
After completing the process in expansion valve vapour enter to evaporator. In the evaporator the vapour is extracts heat and circulating fluid in the surrounding environment and in lower pressure vapour is vaporized.
If without throttling expansion is takes place then the level of temperature will be drop in very low temperature and undergoes sensible heat, latent heat to particularly reach to stage of evaporation.
Increasing Vapor compression refrigeration cycle efficiency in a system is listed below,
Optimize setting
Size of the compressors to match loads as nearly as possible
Install VFDs on screw compressor
Install VFDs on motor of the compressor
Use integrated automation system
Use floating head pressure to maintain ideal temperature.
Actual vapor compression refrigeration cycle:
Actual vapor compression cycle refrigeration cycle is not same process as the theoretical vapor compression refrigeration cycle. In the actual vapor compression cycle loss and unavoidable vapor is present. The refrigerant leaves the evaporator in the state of superheat.
Frequent Asked Questions:-
Question: – Mention the characteristics for good refrigerant.
Solution: – Refrigerant is actually a medium which carry heat during the process of the vapor compression refrigeration cycle. In the refrigeration system heat is absorb from a lower temperature system and after that heat is rejected so system can absorb higher temperature.
The characteristics for good refrigerant is listed below,
Refrigerant should havehigh critical temperature
Refrigerant should havelow boiling point
Non toxic
Non flammable
Non explosive
High latent heat of vaporization
Non corrosiveness for the metals uses in the system of vapor compression refrigeration cycle
Low specific heat of liquidity refrigerant
Low specific heat of vaporized refrigerant
Easy to identified leaks by taking smell or suitable indicator
Easy to liquefy at moderate temperature and pressure.
The main purpose of using a nozzle is to accelerate the velocity of a flowing fluid using pressure. In this article we will discuss about Isentropic Efficiency of Nozzle.
Isentropic efficiency of nozzle is the ratio actual kinetic energy at nozzle exit and isentropic kinetic energy at nozzle exit for the same inlet and exit pressures.
A fluid accelerates in a nozzle as it is moving from high pressure to low pressure with an increase in kinetic energy. Frictional losses inside the nozzle decreases fluid KE and raise the temperature of the fluid, increasing its entropy.
Nozzles are operated under adiabatic condition but the ideal process for a nozzle is the isentropic process. To have a comparison between actual work done and work under isentropic conditions of a device, a parameter called Isentropic Efficiency is used.
The isentropic process involves no irreversibilities and serves as the ideal process for adiabatic devices.
Turbines, compressors and nozzles works under adiabatic conditions. Since they are not truly isentropic, they are considered as isentropic for calculation point of view. Isentropic efficiency is the parameter for a nozzle, turbine or compressor which defines how efficiently these devices approximate a corresponding isentropic device.
Nearer to an idealized isentropic process, improved will be the performance of the nozzle.
IsentropicEfficiency of nozzle is generally greater than 95%. So losses due to irreversibilities are very small in case of a well designed nozzle.
What is a Nozzle?
Nozzles are most widely used steady flow device in steam turbines, gas turbines and rockets.
Nozzle is a device often a pipe or a tube of varying cross sectional area used to control the direction of flow as well as exit velocity, mass, shape and pressure of the flow. Inside a nozzle pressure energy is converted into kinetic energy or we can say the fluid velocity increases with an expense of pressure energy.
Depending on required velocity and mach number of the fluid, Nozzles can be categorised like Convergent type, Divergent type and Convergent-Divergent type. Nozzle can be used for both subsonic and supersonic flows.
In the above figure, a de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow
Isentropic Efficiency of Nozzle Formula
Isentropic Efficiencyrepresents the performance index of a nozzle. A comparison of nozzle’s performance relative to an isentropic process.
Isentropic Efficiency of Nozzle can be defined as the ratio of actual enthalpy drop to isentropic enthalpy drop between the same pressures.
Isentropic Efficiency of Nozzle=Actual enthalpy drop/Isentropic enthalpy drop
Isentropic Efficiency formula is the measure of the deviation of actual processes from the corresponding idealized ones. The ratio of actual work done by a nozzle to work done by the nozzle under isentropic condition is called Isentropic Nozzle Efficiency.
Isentropic Efficiency of a nozzle ηN= Actual Kinetic Energy at Nozzle Exit/ Isentropic Kinetic Energy at Nozzle Exit.
Theoretically the process inside the nozzle is considered as isentropic but due to frictional losses the process is irreversible.
Enthalpy Entropy diagram for a flow inside a nozzle
Process 1-2:Isentropic Process
Process1- 2{}’:Actual Process
Efficiency of nozzle,
For Process 1-2, applying SFEE,
Or,
For Process 1- 2′, applying SFEE,
Or,
Now from Eq(1) substituting the values of h1 – h2 and h1 – h2` ,we get
A Nozzle reduces the pressure of the flow and at the same time speed up the flow to create a thrust.
Some amount of heat loss takes place from the steam due to the friction with the surface of the nozzle. Frictional effect also increases the dryness fraction of steam, because energy lost in friction is transferred into heat which tends to dry or super heat the steam.
In case of fluid dynamics, stagnation point denotes a point where local velocity of a fluid remains zero and isentropic stagnation state represents a state when a flow of fluid goes through reversible adiabatic deceleration to zero velocity.
Both actual and isentropic states are used for gases.
Enthalpy Entropy Diagram for Stagnation State; Image credit: wikipedia
The actual stagnation state is obtained for actual deceleration to zero velocity, irreversibility may be also associated. For this reason stagnation property is sometimes reversed for actual state properties, and the term total property is applied for isentropic stagnation states.
Both isentropic and actual stagnation states have same enthalpy, same temperature(for ideal gas) but may be pressure is more in case of isentropic stagnation state in comparison to actual stagnation state.
In case of a nozzle the inlet velocity is negligible in comparison to exit velocity of a flow.
From the energy balance,
Isentropic Efficiency of Nozzle=Actual enthalpy drop/Isentropic enthalpy drop
Where h1 =specific enthalpy of the gas at the entrance
h2a =specific enthalpy of gas at the exit for the actual process
h2s = specific enthalpy of gas at the exit for the isentropic process
Isentropic Efficiency Nozzle Example
Example: Steam enters a nozzle at 1.4 MPa 2500 C and negligible velocity and expands to 115 KPa and a quality of 97% dry. Determine the exit velocity of the steam.
Solution: Given data , Initial Pressure, P1=1.4MPa
=14 bar
Initial Temperature, T1=2500 C
Final Pressure,P2=115 KPa= 1.15 x 105 Pa=1.15 bar
Quality of steam at exit, x2=0.97
Exit Velocity, V2=?
Neglecting initial velocity, Exit Velocity,
Considering initial velocity,
h1=Enthalpy at initial condition i.e. at 1.14 MPa i.e at 14 bar 2500C, from steam tables,
h1=2927.6 KJ/Kg
h2=Enthalpy at exit condition i.e. at 115 KPa i.e at 1.15 bar x2=0.97, from steam tables
This article answers the question- what does a crankshaft sensor do? Crankshaft sensor is a device used in internal combustion engines to locate the position of crank and its velocity.
We shall discuss the working of an internal combustion engine first, then we shall continue our discussion further with crankshaft sensor and the working of crankshaft sensor. In later sections, we shall also read about different types of internal combustion engines.
What is an IC engine?
An internal combustion engine or IC engine is a heat engine inside which combustion takes place with the help of an oxidizer and working fuel.
IC engine converts this heat energy produced by the combustion of fuel-air mixture to mechanical energy. The main parts of IC engine include Piston, Cylinder, Crank, Spark plugs (In SI engine), crankshaft. We shall discuss more about internal combustion engines in the next section.
Working of internal combustion engine
Internal Combustion engine is an assembly of various mechanical components that work in harmony to produce desired output.
During the intake stroke, the fuel is injected in the system. The piston is connected to connecting rod that connects piston and the crank. As the air fuel mixture is ignited, the piston moves at the bottom dead center and then comes back to the top dead. Due to reciprocating motion of the piston, the crank rotates and in turn helps the wheels to rotate.
How does a crankshaft sensor work?
A crankshaft sensor can be attached to an engine block facing towards the timing rotor or the ring gear attached on the crankshaft. The crankshaft has teeth whose positions are used to determine the actual position of crankshaft.
The sensor will keep a count of the number of teeth that have passed on the ring gear. This information is fed to the engine control unit or engine management system which then calculates the precise position of the crankshaft and decides when the switching on and off of different spark plugs.
The uses of crankshaft sensor are not many but every use is a very significant one. The uses of a crankshaft sensor are given in the section below-
Count the number of teeth passed and feed the information to the engine management system.
Locate the position of crankshaft.
The information about the position of crankshaft is then used to decide the switching on and off of different spark plugs.
Causes of crankshaft sensor failure
There are many causes of failure for a crankshaft sensor. The causes include the following-
Damage– Due to a sudden jerk or excess pressure on the sensor, the sensor may get damaged. Some times the heat gets inside the sensor and melts few components. Such damages lead to crankshaft failure.
Debris – Debris from other broken components can hinder the reading collection process and may lead to crankshaft sensor failure.
Faulty circuitry– When the circuit connections are not proper, the readings from sensor will not be able to reach the engine management system. The sensor will not able to find the correction position of the crankshaft drive and hence the firing order of spark plugs will be uneven leading to more fuel consumption.
How are crankshafts made?
The crankshafts are usually made of steel. The manufacturing processes may vary but commonly they are made using die forging. If the material is cast iron then they are made by casting.4
In casting process, a mould is prepared using a pattern. Then molten cast iron is added to the mould and is left for solidification. Due to solidification, the actual size of casting reduces. To compensate for shrinkage due to solidfication, risers are provided. Risers will have extra molten metal that will be served to the mould in compensation of solidification shrinkage taking place inside the casting.
Cam shaft position sensor
Two sensors- Camshaft position sensor and crankshaft position sensors work together to determine the exact location of the crankshaft. The readings from both of these sensors help the engine management system to find the exact time to know when the first cylinder is in the top dead centre.
The principle on which a cam shaft sensor works is the Hall principle. A rng gear is located on the crankshaft which has many teeth on its circumference. The sensor counts the number of teeth passing by while the ring gear is rotating. Number of teeth that have passed are counted (due to rotation of ring gear) and due to this rotation there is a change in voltage of Hall IC in the sensor head. The voltage change is converted to a readable reading that is the position of crankshaft, this translation is done by the engine management system.
Sensor code P0340
The camshaft sensor simply helps us to determine the location of the crankshaft.
Without the help of this sensor, the engine will not know when to ignite fuel, this will lead to ncrease in consumption of fuel and sometimes this may lead to engine damage.
Sensor code P0340 symptoms
There are different methods by which we can identify P0340 code.
Major symptoms of code P0340 are-
Check engine light on dashboard
Poor acceleration
Engine stalling
Car jerking
Problems shifting gear
Low fuel mileage
Ignition problems
If you observe any of the above symptoms frequently in your vehicle then it is recommended to give the vehicle for servicing specifically targetting the sensor part.
Sensor code P0340 causes
The causes behind the setting of P0340 are given in the section below.
The following list shows the cause of P0340-
Defective sensor
Defective ring gear on the camshaft
Fault in crankshaft sensor
If the wiring inside crankshaft sensor circuit is damaged or corroded.
How serious is P0340?
An alarm alerts the user for any type of emergency situation arising in the system. There are different types of alarms depending upon the intensity of the problem occurring. If the alarm is ignored then it may lead to severe damage to the engine parts.
Initially the engine will start running erratically. The engine’s efficiency will be compromised and even mileage too. If this continue for a longer period of time and it is not treated properly then the engine can be damaged severely due to improper ignition timing.
Camshaft sensor code P0016
Another code relating to camshaft sensor is code P0016.
This is a generic OBD-II code that will indicate the camshaft position sensor about the bank 1 does not correlate to the signal from the crankshaft position sensor.
Symptoms of P0016 code
There are different methods by which we can identify P0016 code.
Some of the symptoms of P0016 code are-
Check engine light turns on.
Engine starts running erratically/abnormally.
The mileage of vehicle decreases due to more fuel consumption.
Reduction in power
Causes of P0016 code
There are multiple ways by which this code can appear.
Major causes of P0016 are-
Oil control valve has restriction in Oil control valve filter
Camshaft timing is out of position.
Camshaft phaser is out of position because of fault with phaser.
How severe is P0016
As discussed for problems pertaining to code P0034, P0016 code has similar problems.
In both the cases the engine starts stalling or running erratically. This is followed by reduction in fuel mileage. And at the end it leads to severe damages to the engine. These damages depend upon the failed part.
What to do after replacing camshaft sensor?
The camshaft sensor must be installed in correct orientation. After orienting in the correct direction, one must reset the sensor before using the vehicle.
The procedure for resetting is very simple. The very first thing one has to do is to focus on switch ON and OFF function, these switches are connected to magnets that need to be adjusted first.
Then we need to check engine light, crank sensor, engine block and see if there is any damage. After doing all of this, trouble codes also need to be checked by code reader and see if there is any problem or not.
After completing the above step, we turn off all the parts that are connected to battery and start driving vehicle at 70 Kmph-80 Kmph for five minutes and then decelerate it to 50-60 kmph. This way the timing chain is changed or the sensor is reset.
If one still faces problems while resetting then he/she should definitely consult a mechanic to perform this procedure.
This article discusses about deep well jet pump diagram. The reader need not have a pre requisite about jet pumps. In this article we shall study about jet pumps as well as deep well jet pump.
A jet pump is simply an assembly of a centrifugal pump, nozzle and a venturi. The jet pump gives out water at high velocity and pressure.
Venturi is used for creating a pressure difference due to which suction increases. We use nozzle to increase the pressure of fluid. In further sections we shall discuss about different types of jet pumps and working of jet pumps in detail.
What is a deep well jet pump?
A deep well jet pump is simply a jet pump that is used to draw waters having depth ranging from 25 ft- 110 ft. This is deeper than usual situations hence the name deep well jet pump.
The working of the deep well jet pump is same as a normal jet pump with the only difference being the diameter of impeller casing, greater the diameter greater the suction and hence greater the depths the jet pump can work on.
Deep well jet pump diagram
A deep water jet pump is used in deep wells. The diagram of deep well jet pump is given in the section below-
The working of a deep well jet pump is similar to a normal jet pump. In the section below we shall study about the working of a deep well jet pump.
In a deep well pump, the pipe which is connected to the impeller casing draws water inside the jet’s body that is located around 10-20 ft deep below the minimum well water level. A second pipe connects to the output of the pump. The centrifugal pump is an assembly of electric motor and impeller, when the motor starts moving the impeller connected to it also starts moving, creating a suction. Later when the fluid passes through venturi more pressure difference is created and the velocity of the fluid is increased.
Types of jet pump
There are two main types of jet pumps. The classification is done on the basis of depth of water that the pumps can draw. For shallow depths we have a different jet pump and for deep water we can use deep water jet pump.
We shall discuss about them in detail. They are given in the list below-
Shallow water jet pump- The name itself suggests that these pumps are used for shallow depths. They can work up to depth of 25 ft. The main idea behind a shallow water jet pump is that they have smaller impeller casings.
Deep water jet pump– Deep water means that the depth of water is more than usual. The depths up to which deep water jet pump can work ranges from 25 ft to 110 ft.
Can you use a jet pump without using a pressure tank?
High pressure jets are used in jet pumps to displace the fluids from one place to another. While in almost every case, a jet pump uses pressure tank that provides high pressure to the stream.
The velocity of fluid is increased with the help of high pressure. The fluid is displaced using the pressure difference created inside the jet pump. However, we can use a jet pump without the help of a pressure tank. But it would cause wearing of the pump due to the pressure generated. So it is recommended to use a pressure tank in a jet pump.
How far can a jet pump pull water?
We have studied about the different types of jet pumps and the depths at which they can be used. Theoretically, at ground levels the jet pump can pull water upto an average depth of 30 feet.
Near vacuum conditions can provide a lifting capacity upto 35 feet. The mentioned numbers are strictly for a shallow water jet pump. In real cases, due to many major losses, the number comes down to 25 feet! Mechanical losses and hydraulic losses contribute to reduction in this number.
Jet pump advantages and disadvantages
We have discussed in detail about the working of jet pump and its types. Now we shall discuss about the different advantages and disadvantages of using a jet pump.
The advantages and disadvantages of jet pump are given in the section given below-
Advantages
It has a great capability to provide high productivity.
Due to less mechanical parts in a jet pump, the chances of wear and tear are less.
The service life is very long.
The maintenance of this pump does not require much efforts and incurs less costs.
If we want to increase or decrease the productivity then with the help of a single injector we can achieve it.
The jet pump can run for longer durations without needing any assistance from us.
The jet pump has a very high tolerance against the abrasives present inside the fluid.
Disadvantages
Other artificial lifts are more efficient than jet pumps.
Space limitation is a major concern while using jet pumps.
Presence of very high pressure surface lines.
Very high power is consumed by jet pumps.
How does a jet pump work on a return fuel system?
Return fuel system is used in internal combustion engines, it comes with a hose that is connected with a carburettor. Sometimes excess fuel is left after a complete combustion cycle, this excess fuel is sucked in by the return fuel system.
Fuel is under high pressure inside the engine cylinder, due to the high pressure a suction is created due to the venturi action inside the pump. As a result of this, excess fuel is drawn towards the fuel tank. The fuel flows through auxilliary pipe system present inside the cylinder.
How does a two line jet pump work?
The name of this jet pump suggests that it uses two pipes. Larger pipe is used for upstream and smaller pipe for downstream.
The two line jet pumps are assisted by venturi that is situated at the bottom of pipes. Water is pumped upward using this venturi. Two line jet pumps can be used in wells, a lake or sometimes even in a water tank.
How does a convertible jet pump work?
This type of pump is versatile in nature. It is mainly used in applications like pumping water from lakes, wells or sprinkler systems.
The same principle that is used in jet engines is used in convertible jet pumps. In convertible jet pumps also, we use nozzle and venturi to pump the water. The internal components of a convertible jet pump is made up of thermo plastics and some times iron too. Since thermo plastics are weaker than iron, the iron parts are long lasting than those made up of thermo plastics.
How does a jet pump work for a jet ski?
We all can refer to jet ski as a water bike. It resembles a bike with the only difference that it runs on water. Jet ski can achieve high speeds, these speeds are achieved with the help of a jet pump.
The jet ski uses the third law of motion to move forward. When we apply the throttle, a centrifugal pump inside the jet ski starts moving as a result of which water is sucked in. The water is taken from the water body itself. The water passes through a nozzle and exits with a very high velocity. Due to high exit velocity the water pushes the jet ski in the forward direction.
