Measurement of local condensation heat transfer coefficient (HTC) within a brazed plate heat exchanger (BPHE) and heat transfer assessment of low-GWP R134a replacements

This paper presents local condensation Heat Transfer Coefficients (HTCs) and temperature profiles of R134a and three low-GWP replacements, R1234yf, R1234ze(E), and R152a, within Brazed Plate Heat Exchangers (BPHEs). The measurement of local temperature profiles allows to couple the evaluation of thermal and hydraulic performances of refrigerants into a single parameter named Total Temperature Penalty (TTP). The experimentation was carried out in a prototype BPHE instrumented with thermocouples inserted into the plate wall to measure the local heat flux and wall temperature. The transition from gravity-controlled condensation to mixed condensation was observed in the refrigerant mass velocity interval 15−20 kg m−2s−1. The experimental HTCs were compared with existing theoretical models finding a Mean Absolute Percentage Error (MAPE) within 10–15 %. The TTP analysis highlights similar condensation performance for R134a, R1234yf and R1234ze(E) refrigerants, while R152a performs better than R134a.