Abstract
In the present study, experiments were performed to examine the characteristics of the two-phase frictional pressure drop of an R410A refrigerant flowing vertically upward and downward for the development of a high-performance heat exchanger using small tubes or mini-channels for air-conditioning systems. The cross-sections of copper test tubes were 0.5, 0.7, 1.0, 1.5, and 2.0 mm circular tubes, and rectangular and triangular tubes with hydraulic diameters of 1.04 and 0.88 mm, respectively. The frictional pressure drops were measured in the range of mass fluxes of 30–400 kg·m−2·s−1, with qualities from 0.05 to 0.9 and a saturation temperature of 10 °C. The characteristics of the measured pressure drops were compared in different inner diameters, cross-section shapes, and flow directions. In addition, Chisholm’s parameter and various modified Chisholm’s parameters for small tubes were examined to determine whether or not they reproduced our measurement data.
Highlights
In order to clarify these, the experiments were performed to examine the characteristics of the two-phase frictional pressure drop of an R410A refrigerant flowing vertically upward and downward
The 351 data were gathered on the two-phase frictional pressure drop in small circular, inrectangular, each tube, and and triangular these datatubes
Experiments were performed to examine the characteristics of the two-phase frictional pressure drop of an R410A refrigerant flowing vertically upward and downward
Summary
As a new high-performance heat exchanger for air-conditioning systems, a heat exchanger using small tubes or multi-port extruded tubes is being developed. To design such heat exchangers, it is necessary to accurately predict the characteristics of frictional pressure drop and heat transfer. Two-phase evaporative flow in small tubes is attractive due to the higher heat transfer coefficient. The evaporation process occurs at a relatively lower pressure condition when compared to the condensation process in the heat pump cycle, so the frictional pressure drop is larger due to the high vapor velocity. The frictional pressure drop may be a factor worth considering when designing a heat exchanger using small tubes
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