Optimal configuration of cross flow plate finned tube condenser based on the second law of thermodynamics

This paper presents a mathematical model for determining optimal configuration of plate finned tube condensers widely used in air conditioning system. The condenser investigated in this work is a cross-flow air-refrigerant type with aluminium plain fin geometry. Refrigerant HFC 134a flows inside while air flows outside the copper tubes. Minimum entropy change of air and refrigerant is used as the criterion for analysis. This entropy change resulting from losses due to heat transfer and pressure drop can be represented in a form of entropy generation number, Ns. The proposed mathematical model is divided into three regions: superheated, two-phase and sub-cooled regions. Effects of heat transfer and pressure drop of air side and refrigerant side on entropy generation rate are simultaneously analyzed through the implicit method. Results from the mathematical model show that entropy generation number decreases with increasing fin pitch and decreasing number of rows and tube diameter. In addition, this work also presents an optimal configuration of condenser. The optimal tube diameter and the number of fin per inch are 6.35–12.7 mm ( inch) and 11–12, respectively.