Evaporating Heat Transfer in Horizontal Internal Spiral-grooved Tubes in the Region of Low Flow Rates

Abstract

This paper presents some experimental data about evaporating heat transfer in horizontal tubes about 4.75mm I.D. with small internal spiral grooves using R efrigerant R12. The groove inclinations of the tested internal spiral-grooved tubes are 4, 7, 15 and 30 degrees. It is found that a spiral-grooved tube can increase the evaporating heat transfer coefficient in tubes from one and a half times to twice as much as that of a smooth tube for annular flow region, and about ten times due to capillary phenomenon in grooves for stratified flow region.