Experimental investigation of condensation heat transfer and pressure drop of R22, R410A and R407C in mini-tubes

Condensation heat transfer and pressure drop of R22, R410A and R407C were investigated experimentally in two single round stainless steel tubes with inner diameter of 1.088 mm and 1.289 mm. Condensation heat transfer coefficients and two phase pressure drop were measured at the saturation temperatures of 30 °C and 40 °C. The mass flux varies from 300 to 600 kg/m² s and the vapor quality 0.1–0.9. The effects of mass flux and vapor quality were investigated and the results indicate that condensation heat transfer coefficients increase with mass flux and vapor quality, increasing faster in the high vapor quality region. The experimental data was compared with the correlations based on experimental data from large diameter tubes (d_h > 3 mm), such as the Shah and Akers correlations et al. Almost all the correlations overestimated the present experimental data, but Wang correlation and Yan and Lin correlation which were developed based on the experimental data from mini-tubes predicted present data reasonably well. Condensation heat transfer coefficients and two phase pressure drop of R22 and R407C are equivalent but both higher than those of R410A. As a substitute for R22, R410A has more advantages than R407C in view of the characteristics of condensation heat transfer and pressure drop.