Study on refrigerant circuitry of condenser coils with exergy destruction analysis

A numerical model of air-cooled condenser coils is proposed to investigate the coil performance. In this model, the properties of refrigerant and air, as well as six exergy destruction components associated with different sources of irreversibility are computed locally along the coil based on numerous control volumes. The governing equations for a control volume are presented together with a computer simulation procedure to link all the control volumes together for a coil. Using this model, the coil characteristics in heat transfer, fluid flow and exergy destruction are analyzed with an emphasis on the refrigerant circuitry investigation. The study shows that the thermal resistance of refrigerant side is comparable to that of air side and the coil performance can be improved by varying the refrigerant mass velocity along the flow path. Compared with a common coil, using a complex refrigerant circuitry that the refrigerant circuits are properly branched or joined may reduce the heat transfer area by approximately 5% in coil design. This study also shows that the quantitative analysis on the exergy destruction components gives a clear picture in the coil performance evaluation. The results show that the criterion of exergy destruction ratio conforms well to that of coil heat flux in coil performance evaluation under the specified conditions.