Evaporation Heat Transfer and Pressure Drop of HFC-134a Inside a Plate Heat Exchanger

An experimental investigation was carried out to provide data on heat transfer coefficient and pressure drop for upward flow of refrigerant 134a in a typical plate heat exchanger. Upflow boiling of R-134a in one channel receives heat from the hot downflow of water in the two adjacent channels. Measurements were conducted on three sets of plates with chevron angles of 0°, 30°, and 60°, and the effects of mean vapor quality, mass flux, and heat flux on the evaporation heat transfer and pressure drop were explored. It was found that the channels with small chevron angle have higher heat transfer than channels with large chevron angle, for both subcooling and vapor quality inlet conditions. It was clear that the heat transfer coefficients were not sensitive to the heat flux but were dependent on the flow conditions (mass velocity and vapour quality). Based on the experimental data, empirical correlations for the evaporation heat transfer enhancement factor and the two-phase pressure drop multipliers were proposed.