11-10-2017, 12:10 PM
Compact heat exchangers are used in a wide variety of applications. They allow for a higher heat transfer rate, require less volume and weigh less compared to other types of heat exchangers. The disadvantage is the greater pressure drop. They are clearly the preferred choice for applications requiring a high heat transfer rate in a limited volume, such as air conditioning devices, heat pumps, car radiators, etc. In these applications the main thermal resistance is located on the air side. Different strategies such as the addition of fins on the air side (eg flat fins, fin fins, groove fins, displaced fin fins, etc.) are used to improve the heat transfer rate, the use of generators vortexing or the application of novel materials (eg metal foams, polymeric heat exchangers, etc.). Only a limited number of fin designs or configurations with new materials have been studied and described in the open literature, since a large set of experiments is required to acquire sufficient data and the space of parameters considered is very large. Currently, these experiments are performed in real heat exchangers or in scaled versions. However, as the computational power and precision of simulation codes increases, more and more research is being done through "numerical experiments", ie computational fluid dynamics (CFD). Careful bench-marking is still very important, especially when optimizing the heat exchanger.