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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

COMPARISON OF EVAPORATION PRESSURE DROP CHARACTERISTICS IN HORIZONTAL THREE-DIMENSIONAL ENHANCED TUBES

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.024252
pages 5131-5140

Abstract

An experimental investigation for in-tube evaporation inside three horizontal newly developed three-dimensional enhanced surface stainless steel tubes (1EHT-1, 1EHT-2 and 4LB) was conducted. The surfaces of the 1EHT tubes were composed of dimples in different sizes and depth, while those of the 4LB tube were made of an array of rectangular protrusions and grooves. The three enhanced tubes had the same outer and inner diameters of 9.52mm and 8.32mm, respectively. The evaporation experiments were performed using R410A as a working fluid at a constant saturation temperature of 279K, and the mass fluxes varied from 160 to 390kg/(m2s). Inlet and outlet vapor qualities were fixed at 0.2 and 0.8, respectively. As the mass velocity increased, the heat transfer coefficient and pressure drop penalty increased accordingly. Experimental results showed that the pressure drop of the 1EHT-1 tube is superior over those of the 1EHT-2 and 4LB tubes. The augmented pressure drop in the three EHT tubes could be attributed to the dimples and protrusion, which provided increased density for nucleation sites on the inner surface, increased surface area and interfacial turbulence. In addition, it was found that the pressure drop during evaporation increases with the increasing depth of the dimples.