How can I find or derive equations for an evaporative heat exchanger?

In summary, the conversation was about building an evaporative heat exchanger for a final project in a college transport phenomena course. The individual was having difficulty finding equations for their specific type of exchanger, which is also known as a cooling tower. The capacity of a cooling tower can be determined by knowing the rate of water evaporation and the airflow and moisture capacity of the air. Resources such as ASHRAE and psychrometric charts can provide this information. Additional information on cooling tower operation was also provided.
  • #1
sicjeff
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I am building an evaporative heat exchanger for my final project in a transport phenomena course in college. I am having difficulty in finding equations that I can either use or derive for my particular type of exchanger.

Does anyone have any ideas where I can find or derive equations to deal with both the condensation and evaporation.
 
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  • #2
An "evaporative heat exchanger" is also known as a cooling tower. Finding the capacity of a cooling tower is surprisingly simple. All you need to know is how fast the water is evaporating. To find that, you need to know the airflow and the moisture capacity of the air. ASHRAE and several other sources can give you typical weather conditions if that is what your air conditions are based on for this project. A psychrometric chart will tell you the properties of the air. Here's some info on cooling tower operation: http://www.engineeringtoolbox.com/cooling-tower-efficiency-d_699.html

Hopefully, that will get you started...
 
  • #3


One way to find equations for an evaporative heat exchanger is to research existing literature and studies on the topic. This can include academic papers, textbooks, and online resources. You can also consult with your professor or other experts in the field for guidance and suggestions.

Another approach is to analyze the physical principles and equations governing heat and mass transfer, such as the heat and mass transfer equations derived from the first and second laws of thermodynamics. From there, you can adapt these equations to your specific evaporative heat exchanger design and operating conditions.

Additionally, you can use computational tools, such as heat exchanger design software, to help you derive equations for your particular exchanger. These tools can provide simulations and calculations based on various parameters and operating conditions.

It may also be helpful to consult with professionals or engineers who have experience in designing and operating evaporative heat exchangers. They may be able to provide insights and equations based on their practical knowledge and experience.

Overall, a combination of research, analysis, and collaboration with experts can help you find or derive equations for your evaporative heat exchanger project. Good luck with your final project!
 

1. What is an evaporative heat exchanger?

An evaporative heat exchanger is a device that uses evaporation to transfer heat from one fluid to another. It typically consists of a series of tubes or plates through which a hot fluid flows, while a cooler fluid is sprayed or dripped over the surface, causing evaporation and heat transfer.

2. How does an evaporative heat exchanger work?

An evaporative heat exchanger works by utilizing the latent heat of vaporization. As the cooler fluid is sprayed or dripped over the surface of the tubes or plates, it absorbs heat from the hot fluid and evaporates. This evaporation process removes heat from the hot fluid, cooling it down. The vapor then condenses on the surface of the tubes or plates, releasing the heat to the cooler fluid.

3. What are the advantages of using an evaporative heat exchanger?

The main advantage of using an evaporative heat exchanger is its high efficiency in transferring heat. It is also a more eco-friendly option compared to other types of heat exchangers, as it does not require any external power source. Additionally, it can be used for a wide range of applications, from cooling water in power plants to air conditioning systems in buildings.

4. What are the common types of evaporative heat exchangers?

The most common types of evaporative heat exchangers include direct contact and indirect contact heat exchangers. In direct contact heat exchangers, the two fluids come into direct contact with each other, while in indirect contact heat exchangers, there is a barrier between the two fluids. Other types include plate and frame, shell and tube, and spray type heat exchangers.

5. What are the limitations of using an evaporative heat exchanger?

One of the limitations of using an evaporative heat exchanger is its susceptibility to scaling and fouling. If the cooler fluid contains impurities, they can accumulate on the surface of the heat exchanger, reducing its efficiency. Additionally, the evaporation process can also lead to water loss, which may need to be replenished. Proper maintenance and regular cleaning can help mitigate these limitations.

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