Plate and Frame Heat Exchanger: What, How, Types, Working, Sizing, Cleaning, Applications


In industrial field in various purposes “Plate and frame heat exchanger” is used. Inside the plate and frame heat exchanger the temperature and transferring of heat is always transfer from higher to lower.

In the industrial area the heat exchangers are used in a large quantity among them the Plate and frame heat exchanger is one of these.Plate and frame heat exchanger uses as a metal plate through which heat can be transfer between present of two fluids. It is carry a frame and clamped between a follower and head.

What is plate and frame heat exchanger?

Plate and Frame Heat Exchanger is a device which is most suitable heat exchanger for exchanging the pressure from low pressure to medium pressure by the medium of fluids of pressure. It is used in free cooling, boilers.

The plate and frame heat exchanger is a device which is uses in a sequence of metal plates where the heat is freely move one fluid to another fluid.  The plates of the plate and frame heat exchanger placed over each other thus it could create a sequence channel so the pressure fluid can move inside of it.

Plate and frame heat exchanger
Plate and frame heat exchanger Image Credit – Wikimedia Commons
Individual plate of plate and frame heat exchanger
Individual plate of plate and frame heat exchanger
Image Credit – Wikipedia

How does plate and frame heat exchanger work?

The plate and frame heat exchanger is a device which is widely uses in small welded designs. The main convenience of the plate and frame heat exchanger is pressure fluid easily can distribute over metal plates.

The gaskets plates of the plate and frame heat exchanger cut down the heat through the surface of the exchanger and help in separate the medium of the hot to medium of the cold. For this reason lower temperature fluid, gas and higher temperature fluid, gas use minimal level of energy.

The working principle of the plate and frame heat exchanger is deeply derive in section of below,

At the start of the process multiple plates are stack together.

Gaskets are used inside the plate and frame heat exchanger thus it could allow preventing fluids which are entering from the alternating plates. The gaskets can easily move left or right side for creating block. In every channel of the plates two fluids will definitely flow. The holes of the gaskets plates in the plate and frame heat exchanger align in this way from a pipe just like a channel from where fluid can flow.

If we go through the plate and frame heat exchanger’s gasket plates then we can observe that the alternates’ gasket plate side is block.

If cooler fluid can pass through the plate and frame heat exchanger then the fluid is entering from the left side top inlet.

After entering the cooler fluid it can flow through the plate 2, plate 4 and plate 6. After that the cooler fluid left a high temperature and discharge from the left side bottom outside.

In the next step the high temperature fluid enters through the right side of the lower inlet then it can flow through the plate 1, plate 3 and plate 5. After that the hot fluid discharges from the right side top outlet.

The gasket of the plate and frame heat exchanger is allowed to flow the fluid inside the particular channel.

In this process the plates which contained the channels from where fluids are flows with different temperature and it has always tendency to flow fluid from hot temperature to cold temperature.  

The higher temperature fluid transfers a little amount of thermal energy to the lower temperature fluid. The different type of two fluids never combines to each other and they never meet to each other just because of the separation is done by the wall of the metal plate. For this reason the lower temperature fluid was getting hot and lower temperature fluid getting cold. The amount of exchange the heat in the plate and frame heat exchanger is simple type.

We should always ensure that, the protective sleeves need to attach with the tightening bars over the threads. Insulated should be kept more thermal energy.

The flow of the fluid is counterflow.

The counterflow working principle is most effective only because of log mean difference of temperature. Logarithmic average of the temperature difference (LMTD) is greatest.

Types of plate and frame heat exchanger:

The plate and frame heat exchanger can be classified into four categories. They are,

  1. Brazed plate and frame heat exchanger
  2. Gasketed plate and frame heat exchanger
  3. Welded plate and frame heat exchanger
  4. Semi welded plate and frame heat exchanger

The types of plate and frame heat exchanger classifications description is given below,

Brazed plate and frame heat exchanger:

The structure of the brazed plate and frame heat exchanger is carry both equipment name gasket and frame. Brazed plate and frame heat exchanger mainly use for small applications but now a day’s brazed plate and frame heat exchanger widely for the large applications. In refrigeration and automotive sector it is use mainly.

In the brazed plate and frame heat exchanger use stainless steel and copper brazing is used to make its plates for this reason it have high corrosion resistive characteristics. This Brazed plate and frame heat exchangers are very lightweight and efficient for this reason this type of heat exchanger is economical.

Brazed plate and frame heat exchanger contain thin metal plates to isolate the pressure fluid, but the metal blades all together to make a full seal. The seal of this heat exchanger is formed with the help of positioning and brazing of the metal plates by which the fluid will be flow can be determined. It contains both high pressure and higher temperature.

The benefits of using brazed plate and frame heat exchanger is,

  1. Exchangers are used.
  2. Low maintenance cost.
  3. Design of construction is easy.
  4. Heat loss is very minimum.

Gasketed plate and frame heat exchanger:

In gasketed plate and frame heat exchanger multiple thin metal sheets are use to make the structure of channel. The heating or cooling capacity can be increases or decreases by adding or subtracting the internal thin metal sheets. The purpose for repair or washing it can also disassemble. The metals which are use to made the thin plates are stainless steel, platinum, and mild steel. In gasketed plate and frame heat exchanger gaskets are made of rubber.

In process engineering, automotive sector, heavy duty HVAC the gasketed plate and frame heat exchanger widely used.

Read more about SUPERHEAT HVAC : IT’S IMPORTANT CONCEPTS AND 3 FAQS

The benefits of using gasketed plate and frame heat exchanger is,

  1. Low maintenance cost.
  2. Leakage can easily prevent.
  3. Replacement of expansion valve is not difficult.
  4. Cleaning of the thin metal plates is not facing difficulty.

Welded plate and frame heat exchanger:

If we looked upon the structure of Welded plate and frame heat exchanger then we can observe the inside structure is so similar with gasketed plate and frame heat exchanger.

The benefits of using welded plate and frame heat exchanger is,

  1. Loss of fluid is very less.
  2. It is highly robust type.
  3. Corrosive or hot fluid can easily move in it.

Semi welded plate and frame heat exchanger:

With the help of two plate’s pair the internal metal plates are made of and they are welded. Another pairs of the gasketeds one pair is welded for making fluid path and another pair is gasketed for making fluid path.

The benefits of using semi welded plate and frame heat exchanger is,

  1. Loss of fluid is very less.
  2. Moving of heavy materials is not facing difficulty.

Plate and frame heat exchanger diagram:

The diagram of the Plate and frame heat exchanger is given below,

Plate and frame heat exchanger
Plate and frame heat exchanger diagram
Image Credit – Wikipedia

Plate and frame heat exchanger applications:

The application of plate and frame heat exchanger are given below,

  1. Heat pump isolation
  2. Water heaters
  3. Waste heat recovery
  4. Free cooling
  5. Cooling tower isolation

Heat pump isolation:

For protecting the heat pump from the contaminants in the supply of water graham plate series exchanger are used. High degree of turbulence cab be easily maintain by graham plate series exchanger, which reducing fouling and appropriate for flowing the higher temperature fluid.

Water heaters:

Stainless steel is used to make water heater. It has high rate of heat transfer and resistivity in corrosion.  In water heater mainly graham plate exchanger are used which is appropriate for flowing the higher temperature fluid.

Water heater
Water heater
Image Credit – Wikipedia Commons

Waste heat recovery:

Waste heat can be generated help of chillers, steam condenser, and many others process is used to making heat of air or water. High efficiency and lower temperature it helps to reduce energy cost.

Free cooling:

For the operation of free cooling chillers of the refrigeration system is shut down and helps to reducing the cost of plant utility. In the free cooling graham plate exchanger are used. During the free cooling process the air is pre cool by the help of cooling tower water.

Cooling tower isolation:

By the help of cooling tower isolation the cooling water is circulated in the buildings. . In the cooling tower isolation graham plate exchanger are used to minimize the turbulence of the water.

Cooling tower
Cooling tower
Image Credit – Wikipedia Commons

Plate and frame heat exchanger sizing:

For the measuring process of Plate and frame heat exchanger sizing is followed some steps. They are,

  1. Get the data of design
  2. Calculating the flux of the heat
  3. Calculating the needed number of thin plates
  4. Confirmation the size of the heat exchanger

Get the data of design:

At the beginning for calculating the size of the plate and frame heat exchanger the first step need to follow is get the data of design. The data which are should to follow to run this process is listed below,

  • Properties present in the fluids.
  • Temperature for each and every fluid in the outlet and inlet.
  • Pressure for the fluid in the inlet.
  • Allowable pressure drop.

Calculating the flux of the heat:

If flowrate of the flowing fluid, specific heat, inlet temperature, outlet temperature or either know the cold side or hot side then heat flux can be easily calculated.

With the help of the formula from which heat flux can be calculated is given below,

[latex]\phi = \dot{m­_h} \ast C_p_h \ast (T_4 – T_3)[/latex]

Where,

mc = Mass flow rate on the lower temperature side in kg per second

Cpc= Specific heat on the lower temperature side

T2= Outlet temperature on the lower temperature side in Kelvin

T1= Inlet temperature on the lower temperature side in Kelvin

h = Mass flow rate on the higher temperature side in kg per second

Cph= Specific heat on the higher temperature side

T4 = Outlet temperature on the higher temperature side in Kelvin

T3 = Inlet temperature on the higher temperature side in Kelvin

By the help of Heat transfer coefficient heat flux can be determined.

Where,

H = Overall heat exchange coefficient in kw.m2.K-1

S = Area of the heat exchanger in square meter

Calculating the needed number of thin plates:

The needed number of thin plates can determined using this formula,

N = S/s

Where,

N = Needed number of thin plates

S = Total area of the heat exchanger area in square meter

s = Size of a particular single plate in square meter

Confirmation the size of the heat exchanger:

Usingthe Nusselt number the size of the heat exchanger can be determined.

[latex]Nu = a * Re^b * Pr^0^.^3^3 * (\frac{P_r}{P_r_w})^0^.^1^3[/latex]

Where,

Nu = Nusselt number

a = Coefficient depending upon the corrugation of plate

Re = Reynolds number

b = Coefficient depending upon the corrugation of plate

Pr= Prandtl number

Prw = Prandtl number at the wall of the plate

Read more about Reynolds number : It’s 10+ Important facts

Plate and frame heat exchanger cleaning and maintenance:

Plate and frame heat exchanger cleaning and maintenance done in three steps. They are listed below,

  1. Scheduled maintenance
  2. Clean in place
  3. Manual maintenance

Scheduled maintenance:

The common process of maintaining Plate and frame heat exchanger cleaning and maintenance is scheduled maintenance. In this process scheduled and regularly maintain and cleaning the apparatus of the heat exchanger. These kinds of cleaning and maintenance process at least stay for six months.

Clean in place:

In this process periodically maintain and cleaning the apparatus of the heat exchanger. This kind of cleaning and maintenance process the plate not need to open it helps to drop excessive pressure inside the heat exchanger.

Manual maintenance:

In this process annually maintain and cleaning the apparatus of the heat exchanger. This kind of cleaning and maintenance process at least stays for more than one year.

Indrani Banerjee

Hi..I am Indrani Banerjee. I completed my bachelor's degree in mechanical engineering. I am an enthusiastic person and I am a person who is positive about every aspect of life. I like to read Books and listen to music. Let's connect through LinkedIn-https://www.linkedin.com/in/indrani-banerjee-2487b4214

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