Entropy generation analysis is a key to evaluating heat transfer augmentation along with pressure drop in enhanced heat exchangers. In the present study, entropy generation during R134a flow condensation inside a helically coiled tube-in-tube heat exchanger is investigated. In that regard, heat transfer and pressure drop contributions to entropy generation are assessed and compared for such condensers. Also, the influence of variation in geometrical parameters and flow conditions on entropy generation is studied. The findings reveal that larger tube diameters and diameter ratios, higher mass and heat fluxes and inlet vapor qualities, and lower saturation temperatures result in higher entropy generation. Additionally, a sensitivity analysis is conducted to analyze such condensers’ sensitivity to changes in geometrical and flow conditions from an entropy generation perspective. The analysis results indicate that at high mass velocities ($G\ge 300$kg.m⁻².s⁻¹) and inlet vapor qualities ($x\ge 0.5$) and low saturation temperatures ($T_{sat}\le {46}^{\circ }C$), coils with larger tube diameters are of higher sensitivity to alterations in aforementioned flow conditions, while coils with different coil diameters are of nearly the same sensitivity at both high and low ranges of flow parameters. On the contrary, when heat flux changes, coils with larger coil diameters are seen to be more sensitive to entropy generation, while coils with different tube diameters show virtually the same level of sensitivity.

熵生成分析是评估增强换热器中传热增强和压降的关键。在本研究中，研究了螺旋盘管管式换热器内 R134a 流动冷凝过程中的熵产生。在这方面，对这种冷凝器的热传递和压降对熵产生的贡献进行了评估和比较。此外，还研究了几何参数和流动条件的变化对熵生成的影响。研究结果表明，更大的管直径和直径比、更高的质量和热通量以及入口蒸汽质量以及更低的饱和温度会导致更高的熵产生。此外，进行敏感性分析以从熵生成的角度分析此类冷凝器对几何和流动条件变化的敏感性。分析结果表明，在高质量速度下 ($G\ge 300$kg.m ^-2 .s ^-1 ) 和入口蒸气质量 ($X\ge 0.5$) 和低饱和温度 (${吨}_{秒\mathrm{一种}吨}\le {46}^{\circ }C$)，具有较大管径的线圈对上述流动条件的变化具有更高的敏感性，而具有不同线圈直径的线圈在流量参数的高低范围内具有几乎相同的敏感性。相反，当热通量发生变化时，线圈直径较大的线圈被认为对熵产生更敏感，而管径不同的线圈表现出几乎相同的灵敏度水平。