Boiling heat transfer of HFO-1234yf flowing in smooth small-diameter horizontal tube.

The boiling heat transfer coefficient of the refrigerant, HFO-1234yf, flowing in a smooth small-diameter horizontal tube with an inner diameter of 2 mm was experimentally investigated. The local heat transfer coefficient was measured at heat flux ranging from 6 to 24 kW/m2, mass flux ranging from 100 to 400 kg/m2.s, evaporating temperature of 288.15 K, and inlet vapour quality ranging from 0 to 0.25. Results showed that, at low vapor quality, the effect of heat flux on the heat transfer was large, whereas at high vapour quality, the effect of mass flux was large. The heat transfer coefficient of HFO-1234yf is almost same as that of R134a. The heat transfer coefficients calculated based on the correlation of Saitoh et al. agreed well with the measured values as compared to other correlations.