Generally, using heat transfer enhancement techniques in heat exchangers always accompanies frictional pressure drop amplification; entropy generation analysis is a suitable technique to investigate the heat transfer and pressure drop together. In this study, the effects of tube's geometrical parameters and flow conditions on entropy generation during two-phase boiling flow of R134a refrigerant in horizontal internally grooved tubes are experimentally investigated. The experimental tests are conducted in a wide range of operating conditions, including mass flux of 16.5–105 kg/m²s, vapor quality of 0.06–0.98, and heat flux of 3.5–25 kW/m². Test evaporator tubes are made up of copper of 20 mm inner diameter with nine types of discrete inclined grooves on the tubes' internal wall surface. The results represent that using the grooved tubes is desirable for the majority of test conditions except for mass fluxes between 20 and 80 kg/m²s at vapor qualities higher than about 0.4–0.5. The ratio of groove pitch length to groove width within the geometrical parameters has the most notable effect on the total entropy generation. Besides, a new correlation is developed for entropy generation of R134a evaporating flow inside internally grooved tubes with discrete inclined grooves.

通常，在热交换器中使用传热增强技术总是伴随着摩擦压降的增加。熵产生分析是一种适合同时研究传热和压降的技术。在这项研究中，实验研究了管的几何参数和流动条件对水平内槽管中R134a制冷剂的两相沸腾流动过程中熵产生的影响。实验测试在各种运行条件下进行，包括质量流量16.5–105 kg / m ² s，蒸汽质量0.06–0.98和热流量3.5–25 kW / m ²。测试蒸发器管由内径为20 mm的铜制成，在管的内壁表面上有九种类型的不连续倾斜凹槽。结果表明，在大多数测试条件下，使用沟槽管是理想的，除了蒸汽质量高于约0.4-0.5的质量通量在20至80 kg / m ² s之间。几何参数内的凹槽节距长度与凹槽宽度之比对总熵产生最显着的影响。此外，开发了一种新的相关性，用于在具有离散倾斜凹槽的内部凹槽管内生成R134a蒸发流的熵。