Design of plate heat exchanger

In summary, Baluncore is an expert summarizer of content. He does not provide any design or optimization advice. However, he does mention that countercurrent flow is a more efficient way to exchange heat. He also mentions that the flow rates of the fluids must be different in order to get the best results. He also mentions that the final temperatures will be higher than if the fluids were flowed in a parallel manner. He also mentions that the heat needed to exchange is based on the design of the plate heat exchanger.
  • #1
Alfred0812
2
0
I am currently working on my college project about the design and optimization of plate heat exchanger. However, i have no idea where to start the project. Here is my first thought:
- I set the hot and cold fluid to be water, 90 degC for the hot inlet and 30 degC for the cold inlet.
- 50mm inlet and outlet portholes.
- 500mm height and 300mm wide for the plate ( 500x300 is the full dimension of the plates).

I did some research about the plate and got that the plate have chevron corrugation which help in heat transfer, while the corrugation inclination angle has a range of 25 deg - 65 deg.

I also found that the design must consider the pressure, mass flow rate, fluid velocity and many other parameters. I am not sure how to begin the design and what parameters should I emphasize on. Besides, since the PHE is designed by myself, is that possible to further optimize it?

p/s: I have no idea about the difficulty when i choose this title. Need a lot of helps on my project.
 
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  • #2
Are you aware that you can get twice the heat exchange by using a counter current flow exchanger.
https://en.wikipedia.org/wiki/Countercurrent_exchange
How can you increase the time available for heat exchange, or reduce the distance heat must be conducted through the water or plate ?
Does it have to remain a flat plate or can it be rolled into two coaxial tubes, one inside the other ?
 
  • #3
Baluncore said:
Are you aware that you can get twice the heat exchange by using a counter current flow exchanger.
https://en.wikipedia.org/wiki/Countercurrent_exchange
How can you increase the time available for heat exchange, or reduce the distance heat must be conducted through the water or plate ?
Does it have to remain a flat plate or can it be rolled into two coaxial tubes, one inside the other ?
Hello Baluncore, as what i know the countercurrent flow is 2 fluids flow in opposite direction, the heat transfer efficiency is much more higher than that of concurrent flow. I am not sure whether the heat exchange by countercurrent can be 4 times(?) higher than that of concurrent.
For the time available for heat exchange, can i increase the distance from the inlet port to outlet port? Or reduce the fluid velocity? In this case, does the fluid pressure affect the time for heat exchange? Can I take the distance of heat conducts as the thickness of plate? Heat transfer occurs through hot fluid > plate wall > cold fluid, can i just emphasize on the heat transfer between fluid and wall and neglect the heat transfer within the fluid?
I think my thought of plate heat exchanger is fluid pass through the plates, no tubes involve.
 
  • #4
Alfred0812 said:
I am not sure whether the heat exchange by countercurrent can be 4 times(?) higher than that of concurrent.
There is no 400%.
If two fluids counterflow then exchange between the two can be close to 100%.
If two fluids flow parallel then exchange between the two is limited to 50%.
See; https://en.wikipedia.org/wiki/Countercurrent_exchange#Cocurrent_flow.E2.80.94half_transfer

Alfred0812 said:
For the time available for heat exchange, can i increase the distance from the inlet port to outlet port? Or reduce the fluid velocity?
Yes. That must be considered. But is it better to use a wider channel or a longer channel? You must allocate the available volume by cost benefit analysis.

Alfred0812 said:
In this case, does the fluid pressure affect the time for heat exchange?
Pressure is not an important exchange parameter. But the pressure needed to push fluid through the exchanger will depend on design of the fluid path.

Alfred0812 said:
Can I take the distance of heat conducts as the thickness of plate?
Plate material thickness should be reduced for better transfer, but must withstand the pressure differential between the ports and fluids.

Alfred0812 said:
Heat transfer occurs through hot fluid > plate wall > cold fluid, can i just emphasize on the heat transfer between fluid and wall and neglect the heat transfer within the fluid?
Heat transfer within fluid is most important. That is why turbulence is sometimes encouraged to avoid laminar flow.
The plate surface is also important as scale deposits or oil may prevent heat flow on either side of a plate.

Alfred0812 said:
I think my thought of plate heat exchanger is fluid pass through the plates, no tubes involve.
Yes. Single plates separate alternate fluids A and B. Can you arrange for fluid A inlet at the same end as fluid B outlet. B inlet at A outlet. That will give you counterflow efficiency. But how do you arrange the holes and seals between plates to get the best flow path?

Alfred0812 said:
I set the hot and cold fluid to be water, 90 degC for the hot inlet and 30 degC for the cold inlet.
What is the flow rate of the fluids? Are the flow rates different?
What will final temperatures be? How much heat do you need to exchange?

Everything will have a cost and a benefit. You must establish the relationships between all parameters of the design. Then solve the system of relationships for a minimum cost and a maximum benefit. You will need to know the cost of energy and the time to pay off the investment in the exchanger.
 
  • #5
@Alfred0812 You need to do some basic research as preparation for this project .

Try putting the obvious keywords into a search engine :

Plate heat exchanger design or Plate heat exchanger calculations .

You will find lots of good information .
 

1. What is a plate heat exchanger and how does it work?

A plate heat exchanger is a type of heat transfer device that is used to transfer heat between two fluids. It consists of a series of stacked plates with alternating channels for the hot and cold fluids to flow through. The heat is transferred between the two fluids through the plates, without them actually coming into contact with each other. This allows for efficient heat transfer without the risk of contamination or mixing of the two fluids.

2. What are the advantages of using a plate heat exchanger?

Plate heat exchangers have several advantages over other types of heat exchangers. They have a larger surface area for heat transfer, which results in higher efficiency. They are also compact in size, making them ideal for use in limited spaces. Additionally, they can be easily disassembled for cleaning and maintenance, and can handle high pressures and temperatures.

3. How do you determine the design parameters for a plate heat exchanger?

The design parameters for a plate heat exchanger depend on several factors, including the type of fluids being used, the desired heat transfer rate, and the available space for the exchanger. These parameters are determined through calculations and simulations, taking into account the heat transfer coefficients, pressure drops, and other variables.

4. Can a plate heat exchanger be used for different types of fluids?

Yes, plate heat exchangers can be used for a wide range of fluids, including liquids, gases, and even steam. However, the materials used for the plates and gaskets may need to be selected based on the specific properties and compatibility of the fluids being used.

5. How do you ensure the efficiency and performance of a plate heat exchanger?

Regular maintenance and cleaning are essential for ensuring the efficiency and performance of a plate heat exchanger. This includes inspecting and replacing any damaged or worn plates and gaskets, as well as removing any buildup or fouling that can decrease heat transfer. Proper installation and operation of the exchanger also play a crucial role in maintaining its efficiency and performance.

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