Experimental study on boiling heat transfer of R32/R290 in horizontal tubes.

In this paper, because of the high GWP of R407C and R410A which are widely used as alternatives for R22 at present, a new mixture of R32 and R290 is proposed as the alternative of R22. R32/R290 mixture with mass ratio 68/32 is a near-azeotropic refrigerant. The ODP of this mixture is zero, its GWP is much lower than R410A. The flow boiling heat transfer performance inside a single horizontal tube with different inner diameters was investigated with the mass flow rate from 100kg/(m2•s) to 250 kg/(m2•s) and the evaporation temperatures are 7°C, 9°C and 11°C, respectively. The effects of refrigerant mass flow and the evaporation temperature on the heat transfer coefficient are analyzed. The results have a certain reference value for the engineering design and optimization of R32/R290 evaporators.