Heat Transfer And Pressure Drop Characteristics Of R410A-Oil Mixture Flow Boiling In 7mm C-Type Smooth Tube

Due to the phase-out of R22 early this century, searching for a replacement for R22 has been intensified in recent years. The near azeotropic refrigerant mixture of R410A has been considered as one of the primary replacements for R22 in the air-conditioning system. In real air-conditioning, in order to lubricant and seal the compressor, there is amount of oil in compressor, and the oil will enter into evaporation with the refrigerant, which affects the evaporation heat transfer and pressure drop characteristics of refrigerant. C-type heat exchanger can meet some requirement in some special situation, so the characteristics of C-type evaporation needed be studied. In order to improve the performance of air-conditioning, this thesis study the heat transfer and pressure drop characteristics of R410A-oil mixture flow boiling in 7 mm C-type horizontal smooth tube need be studied.The evaporation heat transfer and pressure drop characteristics of R410A-oil flow boiling in 7 mm C-type horizontal smooth was studied,and the conclusions follow as:(1) The effect of mass flux, quality, and oil concentration on heat transfer was studied. According to refrigerant-oil mixture property method, a new heat transfer correlation suiting to R410A-oil flow boiling in 7 mm C-tye smooth tube was developed. Under test conditions, heat transfer of R410A-oil mixture increase with the oil concentration, mass flux. When oil concentration increase from 0% to 5%, the largest enhance of heat transfer coefficient is 30.1%. The effect of quality on heat transfer different with the change of oil concentration and mass flux. With the increase of mass flux, the effect of oil on heat transfer decrease, and that the same with the increase of quality. The prediction of new heat transfer correlation match with more than 90% of experimental data within the deviation of±15%, and the largest deviation is 21.9%, average deviation is 5.1%.(2) The effect of mass flux, quality, and oil on pressure drop was studied. According to refrigerant-oil mixture property method, a new pressure drop correlation suiting to R410A-oil flow boiling in 7 mm C-tye smooth tube was developed. The pressure drop of R410A-oil mixture increase with the increase of oil concentration, quality, mass flux. When oil concentration increase from 0% to 5%, the largest increase of pressure drop is 26.9%. The effect of oil on pressure drop decrease with the increase of mass flux and quality. The prediction of new correlation match with more than 80% experimental data within the deviation of±15%, and the largest deviation is 28.97%, average deviation is 9.13%.