Flow boiling of R32 inside a brazed plate heat exchanger

This paper presents measurements of heat transfer coefficient obtained during flow boiling of R32 inside a brazed plate heat exchanger (BPHE). Although R32 is known as a very interesting refrigerant for its thermodynamic and thermophysical properties, very limited flow boiling data are published in the open literature for R32 working in brazed plate heat exchangers.The present experimental data are measured to investigate the effect of refrigerant heat flux, mass velocity, inlet vapor quality and superheating at the outlet. The saturation temperature is kept constant at around 5 °C, which is a usual temperature level for evaporation in liquid coolers. As a significant result, differently from other studies on flow boiling with HFC refrigerants, mass flux is found to be very important, meaning a high contribution of the convective term on the heat transfer coefficient.The present data are also analyzed to assess available correlations for flow boiling inside BPHEs, in order to provide useful information on the accuracy of predicting methods that can be used for evaporators with R32.