Hydrocarbon refrigerants condensation local heat transfer coefficients inside a brazed plate heat exchanger (BPHE)

This paper presents the local heat transfer coefficients of R290 (propane) and R1270 (propylene) condensation inside a Brazed Plate Heat Exchanger (BPHE). A new test section was designed for measuring the local heat transfer coefficient in refrigerant two-phase heat transfer in a BPHE. The test section includes two corrugated plates instrumented with 36 T-type thermocouples for measuring the local plate surface temperature, the local heat flux and the local heat transfer coefficient in 9 positions along the refrigerant channel. The experimental tests were carried out at a condensation temperature of 30°C, in the refrigerant mass flux range 5 − 17.5 kg m−2s−1 with an inlet vapour quality around 1.00 and an outlet vapour quality ranging from 0.13 to 0.17. A transition point between gravity-dominated and forced convection condensation was found for a refrigerant mass velocity around 10 kg m−2s−1. The experimental data was compared against theoretical models: Nusselt (1916) analysis for vertical surface shows a fair agreement with the data in gravity-dominated condensation, while Longo et al. (2015) model predicts the data in forced convection condensation with a Mean Absolute Percentage Error (MAPE) around 20%. The experimental data were further compared with some original measurements obtained with R404A and with data available for R410A. R290 and R1270 exhibit condensation heat transfer coefficients similar to those of traditional HFC refrigerants, such as R410A and R404A.