Refrigeration Heat Exchanger Design (Evaporator and Condenser)

In summary, the conversation is discussing the estimation of the total heat transfer area for the hot and cold sides of a domestic refrigeration system. The formula for the evaporator is mentioned and the values needed for its calculation are listed. The person is trying to estimate the area in order to calculate the overall heat transfer coefficient, but has not been successful so far. It is mentioned that fins are usually used on evaporators to help with heat transfer. The goal of the project is to find the optimal heat transfer ratio between the hot and cold sides.
  • #1
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1
Hi There

Based on a Vapour compression refrigeration system:
Does anyone out there know a good estimate or any real values for the total heat transfer area for the hot and cold sides of a domestic refrigeration system? i.e. the sum of the areas of the evaporator and the condenser.

For the Evaporator:
QL=UL.AL.(TL-T1)

AL=heat transfer area of cold side (Low side)=?
UL=overal heat trans. coefficient of cold side.=?
QL=heat removed from cold side = 7.93 KW
TL=refrigerator temp. = 3degs C + 273.15=276.12 Kelvin
T1= Refrigerant evaporating temp. =0degs C + 273.15= 273.15 Kelvin

I am trying to estimate this area so I can calculate the overal heat transfer coefficient which I need for other calculations. So far the outcome of estimating the area and finding the heat transfer coefficient based on it has not been realistic.

If it helps:
The aim of my project is to find the optimal heat transfer ratio between hot and cold side, there is theory on this which I am following, I just need some realistic values for area and heat transfer coefficient. I think it is more logical to estimate the area and find the h.t. coefficient based on that rather than the other way around.
 
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  • #2
Normally evaporators have some kind of fins (maybe just a plate that evaporator tubes are pressed into) as the resistance on the air side is much greater than that of the refrigerant to heat exchanger side.
 

1. How does an evaporator work in a refrigeration system?

The evaporator is a heat exchanger that is responsible for absorbing heat from the surrounding environment. It utilizes a refrigerant, which is a substance that can easily change from a liquid to a gas and back again, to transfer heat from inside the refrigeration system to the outside. The refrigerant evaporates as it absorbs heat, and this process cools the air or liquid that is being circulated through the evaporator.

2. What factors are important to consider when designing an evaporator?

There are several important factors to consider when designing an evaporator, including the desired cooling capacity, the type of refrigerant being used, the available space for the evaporator, and the desired temperature range for the cooling process. Other factors such as cost, energy efficiency, and maintenance requirements should also be taken into account.

3. How does a condenser work in a refrigeration system?

The condenser is also a heat exchanger, but it works in the opposite way of the evaporator. It is responsible for releasing heat from the refrigerant, which has been compressed and heated up in the compressor. As the refrigerant cools and condenses back into a liquid, it releases heat to the surrounding environment, completing the cooling cycle.

4. What are the different types of condensers used in refrigeration systems?

The most common types of condensers used in refrigeration systems are air-cooled, water-cooled, and evaporative condensers. Air-cooled condensers use air as the cooling medium, while water-cooled condensers use water. Evaporative condensers use a combination of air and water to cool the refrigerant. The type of condenser used depends on factors such as the availability of water, the ambient temperature, and the desired cooling capacity.

5. How can the efficiency of a refrigeration heat exchanger be improved?

There are several ways to improve the efficiency of a refrigeration heat exchanger, such as increasing the surface area of the heat transfer surfaces, using more efficient materials, optimizing the refrigerant flow rate and temperature, and minimizing the temperature difference between the refrigerant and the surrounding environment. Regular maintenance and cleaning of the heat exchanger can also help improve its efficiency.

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