Convective boiling of R-407c inside horizontal microfin and plain tubes

This work presents experimental results on the nucleate and convective boiling of R-407c, flowing with a mass velocity in the range 200–300 kg m −2 s −1, at 770 kPa, inside horizontal plain and microfin tubes with outside diameters (OD) of 7.0 and 12.7 mm. The data are presented for heat fluxes of 10 and 20 kW m −2. The experimental data are discussed in terms of the heat transfer coefficient and the pressure drop as a function of the vapor quality. For a heat flux of 10 kW m −2 and a mass velocity of 200 kg m −2 s −1, the dominant heat transfer mechanisms for the 7 mm OD tube is the nucleate boiling regime whereas for the 12.7 mm OD tube it is the convective boiling regime.