Experimental investigation of gravity and channel size effects on flow boiling heat transfer under hypergravity

Understanding of flow boiling heat transfer under hypergravity is needed due to its applications to modern flight vehicles. Few investigations on this issue have been reported. The present paper presents the experimental results of R134a flow boiling heat transfer in 1.002 and 2.168 mm ID tubes under hypergravity up to 3.16 g. The results reveal effects of gravity, channel size, heat flux, mass flux, quality, and pressure on and their interrelations in flow boiling heat transfer. Gravity has strong effects on flow boiling heat transfer. The heat transfer coefficients (HTCs) under hypergravity levels up to 3.16 g are normally greater than those under Earth's gravity. The heat transfer characteristics in the 1.002 and 2.168 mm tubes are very different, indicating that gravity effects on flow boiling heat transfer strongly interrelate with channel size. Also, gravity effects on flow boiling heat transfer are influenced by heat flux, mass flux, and pressure, and somewhat related to quality. (C) 2019 Elsevier Masson SAS. All rights reserved.