Experimental study on flow boiling heat transfer and pressure drop of refrigerant R-32 in a horizontal tube

Due to the global warming effect consideration, the refrigerant which has lower value of the Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) will be choose as the next generation refrigerant used in the industry, especially in the air-conditioner. New developed refrigerant R-32, which GWP is 675, has proposed to replace R-410A and has one-third lower GWP than it, so it is supposed to be a good candidate for replacing R-410A. In this research, flow boiling heat transfer coefficients and pressure drops of R-32 have been measured in a horizontal tube with an inner tube diameter 5mm, comparing them with different saturation temperature at 10°C. The test section is a double pipe heat exchanger, where R-32 flows in the tube side and water flows in the shell side. Heat transfer coefficients of the R-32 was calculated by modified Wilson Plot method. Test results of R-32 for single-phase heat transfer and friction factor are agree with Petrukhov [1970] and Blasius [1913] equations. Experiments were conducted vapor quality form 0.2-0.9 with mass flux at 400. Experimental results of heat transfer and pressure drop characteristics were clarified, and their results also comparing with some correlations.