Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5017124 | International Journal of Refrigeration | 2017 | 31 Pages |
Abstract
This study investigated the effect of tube diameter on flow boiling characteristics of refrigerant R32 in horizontal small-diameter tubes with 1.0, 2.2, and 3.5âmm inner diameters. The boiling heat transfer coefficient and pressure drop were measured at 15â°C saturation temperature. The effects of mass velocity, heat flux, quality, and tube diameter were clarified. The flow pattern of R32 for adiabatic two-phase flow in a horizontal glass tube with an inner diameter of 3.5âmm at saturation temperature of 15â°C was investigated. Flow patterns such as plug, wavy, churn, and annular flows were observed. The heat transfer mechanisms of forced convection and nucleate boiling were similar to those in conventional-diameter tubes. In addition, evaporation heat transfer through a thin liquid film in the plug flow region for low quality, mass velocity, and heat flux was observed. The heat transfer coefficient increased with decreasing tube diameter under the same experimental condition. The fictional pressure drop increased with increasing mass velocity and quality and decreasing tube diameter. The experimental values of the heat transfer coefficient and frictional pressure drop were compared with the values calculated by the empirical correlations in the open literature.
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Physical Sciences and Engineering
Engineering
Mechanical Engineering
Authors
Daisuke Jige, Kentaro Sagawa, Norihiro Inoue,