Horizontal flow boiling of R22, R134a and their mixtures with oil in smooth and enhanced tubes

The experimental stand and procedure for flow boiling investigations are described. Experimental data for pure R 22, R134a and their mixtures with oil in two smooth tubes and two enhanced tubes are also presented. The performance benefits of the micro-fin tube and corrugated tube are quantified and discussed. During tests inlet vapour quality was set 0[plus-minus]0,05 and outlet quality 0,7[plus-mines]0,01. Mass flux density varied from about 250 to 500 kg/m[^2]s. The experiments have been conducted for average saturation temperature 0[degrees]C. The ability of selected models to predict the boiling heat transfer coefficient is evaluated by comparison with the experimental data obtained in smooth tubes for pure R 22 and R134a.