microchannel, circuitry, simulation, model, serpentine
Microchannel heat exchangers (MCHX) play an important role in topics about charge reduction and transcritical cycles due to its high compactness and high mechanical strength. From a designer’s point of view, given an air-side area and face area, there are many options to design the refrigerant circuitry and aspect ratio of a MCHX. The paper presents numerical studies about the influence on the MCHX’s performance of these design parameters for a condenser working with propane and a gas cooler working with CO2. A technique to improve the MCHX effectiveness is to cut the fins along the middle section between neighboring tubes. Following same methodology as was used in previous study, the paper analyzes the improvement by cutting fins for different condensers layouts. A key point of the paper is that the parameters analyzed can only be assessed by models which take into account heat conduction between tubes, otherwise their effects would be hidden. Results illustrate the presence of an optimum circuitry in order to maximize heat transfer of condensers working in similar conditions. Improvement on the condenser heat transfer by cutting fins depends on the layout which turned to as much as 4%. Impact of heat conduction between tubes was higher and clearer in case of gas cooler.