Local heat transfer coefficients of R32 and R410A boiling inside a brazed plate heat exchanger (BPHE)

This paper presents the local heat transfer coefficients of R32 and R410A boiling inside a Brazed Plate Heat Exchanger. A new and innovative test section, with one channel on the refrigerant-side and two channels on the water-side, was specifically designed and manufactured for measuring the local heat transfer coefficient in refrigerant two-phase heat transfer in BPHE. The test section includes two thick corrugated plates instrumented with 36 copper-constantan thermocouples for measuring the plate surface temperature, the heat flux and the heat transfer coefficient in 9 different positions along the refrigerant channel. The experimental tests were carried out at a saturation temperature around 10 degrees C, in the refrigerant mass velocity range 9.7-39.3 kg m- 2s- 1 with an inlet vapour quality ranging from 0.28 to 0.38 and an outlet vapour quality around 1.00. R32 and R410A exhibit boiling heat transfer coefficients very similar both in trend and magnitude. Nucleate boiling seems to be the governing heat transfer regime both in R410A and R32 tests. Consolidated correlations for boiling inside BPHE show a fair agreement with all the experimental data.