ORC 工况R134a 在强化管内流动换热研究

ORC is an effective method to recover waste heat, in which the evaporator is a vital part. However, flow boiling characteristics of organic fluids in enhanced tubes for ORC conditions has not been studied well. Therefore, experiments of R134a flow boiling in enhanced tubes for the ORC working conditions were conducted to obtain the flow boiling characteristics and provide references for the design of evaporators. In this study, variation of heat transfer coefficient and wall temperature with vapor quality is obtained, and the effects of mass flow rate and saturation pressure on the heat transfer are analyzed. The results showed that the heat transfer coefficient decreases with the increase of vapor quality. Increasing mass flow rate can increase heat transfer coefficient, while increasing system pressure is not conducive to heat transfer enhancement. Comparison between the experimental data of smooth tube and enhanced tube shows that the enhanced tube can significantly inhibit wall temperature separation, thereby enhancing heat transfer.