Flow boiling heat transfer and pressure drop of hydrocarbons R600a and R290 in a multiport mini channel tube.

The design of compact evaporators for refrigeration systems has motivated the research in flow boiling for better understanding of heat transfer, pressure drop and modelling improvement. This work presents the results of experimental studies of flow boiling of R600a and R290 in a multiport tube with 1.47 mm ID. The effects of heat (q”=5-20 kW/m²) and mass flux (G=35-170 kg/m²s) on heat transfer coefficient, h, and pressure drop, delta p, were studied for Tsat=20 oC. The h reached values up to 18 and 9 kW/m²K for R290 and R600a, respectively. The influence of G on delta p was observed, and the highest loss for R600a. The flow patterns during the tests were plug, slug and annular, but with differences in minichannels. The patterns for R600a evolved to annular faster than R290.