Conventional modeling of condensers always assumes three zones: desuperheating, condensation and subcooling even condensation occurs in desuperheating zone at some conditions and that subcooling occurs during condensation. This paper discusses the actual situation and provides experimental validation of the hypothesis. The experimental results show heat transfer coefficients of CO2 and R410A at mass fluxes 100 to 240 kg m-2s-1 and reduced pressures from 68% to 100% in a horizontal smooth tube of 6.1 mm inner diameter. Data are compared to correlations proposed for other working fluids or other conditions. Results show much higher values of HTC than correlation proposed for single-phase turbulent flow in superheated zone. The occurrence of condensation in superheat zone is evident when tube wall temperature is below saturation temperature. The results suggest that simplified calculations of heat rejection in superheated zone significantly oversize the condenser. The semiempirical correlation, which is here proposed as the combination of existing correlations for single-phase turbulent and saturated condensation, satisfactorily predicts the heat transfer coefficient of the superheat zone condensation.
展开▼
机译：冷凝器的常规建模始终假定为三个区域：减温，冷凝和过冷，甚至在某些条件下在减温区域中甚至会发生冷凝，并且在冷凝期间会发生过冷。本文讨论了实际情况，并提供了假设的实验验证。实验结果表明，在内径为6.1 mm的水平光滑管中，当质量通量为100至240 kg m-2s-1时，CO2和R410A的传热系数为68％至100％。将数据与为其他工作流体或其他条件建议的相关性进行比较。结果显示，HTC的值比过热区中单相湍流所建议的相关性高得多。当管壁温度低于饱和温度时，就会在过热区发生冷凝现象。结果表明，简化的过热区排热计算显着增大了冷凝器的尺寸。在这里提出的半经验相关性是单相湍流和饱和凝结的现有相关性的组合，可以令人满意地预测过热区凝结的传热系数。
展开▼
