Numerical and analytical approach to study condensation for automotive heat exchangers

Abstract

Heat exchanger (condenser, evaporator etc.) is one of the essential component in the automotive air conditioning system. In these heat exchanger the phase change phenomenon involves, which makes the calculation complicated. In this study, two different approaches are used to analyze the condensation phenomena inside the automotive condenser. The first approach, an analytical study based on empirical correlation is used to calculate the heat transfer and internal pressure drop of the condenser and it is validated with experimental results. In analytical approach, condenser is discretized into multiple segments and ε-NTU method is applied in each segment to calculate the heat transfer and internal pressure drop. In the second approach, Computational Fluid Dynamics (CFD) is used to analyze condensation phenomena inside the microchannel and it is compared with the analytical results. The maximum deviation of heat transfer and internal pressure drop (refrigerant side) for the analytical approach is found to be 8.3% & 9.4% respectively compared to experimental results. In CFD simulation, the condensation of refrigerant commenced from 125 mm in the first pass along the length of the tube (in the direction of refrigerant flow), while the same is begun from 128 mm in the case of analytical approach. Beside to that the dryness fraction across all the passes of the condenser is compared between these approaches.