Experimental data of heat transfer coefficient during evaporation of R-1234yf, R-134a, and R-22 in horizontal circular small tubes are compared. The local heat transfer coefficient is obtained for heat fluxes ranging from 10 to 35 kW [m.sup.-2], mass fluxes ranging from 100 to 650 kg [m.sup.-2] [s.sup.-1], saturation temperatures of 5,10, and 15[degrees]C, and quality up to 1.0. The test sectio…