Experimental investigation of in-tube condensation in microgravity

Abstract This work is aimed at studying the effect of gravity when convective condensation occurs inside a small diameter channel. An experimental apparatus has been specifically designed to perform microgravity experiments during the 62nd ESA Parabolic Flight Campaign. Convective condensation heat transfer tests have been carried out at mass velocity between 70 kg m −2  s −1 and 170 kg m −2  s −1 using HydroFluoroEther HFE-7000 (1-methoxyheptafluoropropane) as the working fluid in a circular cross section channel with an internal diameter equal to 3.4 mm. The data of heat transfer coefficient and the flow pattern visualizations show that, when gravity acts perpendicular to the channel flow, it has a beneficial effect on the heat transfer coefficient by acting on the liquid distribution along the channel perimeter. In microgravity conditions this mechanism leads to a penalization which is proportional to the mass velocity.