Natural refrigerants such as carbon dioxide (R744), ammonia (R717) or propane (R290) have been considered as promising candidates for the next generation in order to make the friendly environment refrigeration systems. This study investigates the two-phase flow heat transfer coefficient and pressure drop of ammonia and propane during the evaporation inside a minichannel multiport tubes. The tube has a hydraulic diameter of 0.83 mm. The length of test section is 200 mm. The experimental data were conducted at saturation temperatures of 6 °C, the heat flux from 3 to 12 kW/m2, the mass flux varied from 50 to 150 kg/m2s and the quality up to a unit. The effects of mass flux, heat flux and vapor quality on heat transfer coefficient and pressure drop are analyzed. Also, the heat transfer coefficient data were compared with various correlations in the literature.
Keywords R-717, R-290, Heat Transfer Coefficient, Pressure drop, Multiport Tube, Natural Refrigerant