Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers
Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers
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DOI：
10.3390/en13051031
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发表时间：
2020-03-01
期刊：
影响因子：
3.2
通讯作者：
Tassou, Savvas A.
中科院分区：
文献类型：
--
作者：
Chai, Lei;Tsamos, Konstantinos M.;Tassou, Savvas A.
本文研究了翅片管超临界二氧化碳 (sCO(2)) 气体冷却器在制冷剂压力接近临界点时的热工水力性能。我们开发了一种与 epsilon-NTU 方法相结合的分布式建模方法，用于气体冷却器的仿真。使用努塞尔数和摩擦系数的经验相关性计算每个均匀划分段的传热和压降。该模型根据测试结果进行了验证，然后用于研究设计和操作参数对局部和整体气体冷却器性能的影响。结果表明，制冷剂传热系数随着温度的降低而增加，并在接近准临界温度时达到最大值，然后开始下降。随着温度的降低，沿流动方向的压降增加。总体性能结果表明，较高的制冷剂质量流量和减小的翅片管直径可提高传热速率，但也会增加压降。气体冷却器的设计优化应考虑其对整体制冷性能和生命周期成本的影响。这对于减少制冷和热泵系统的组件占地面积、能源消耗以及环境影响非常重要。目前的工作为翅片管气体冷却器的设计提供了实用指导，并且可以作为集成 sCO(2) 制冷和热泵系统建模的基础。
This paper investigates the thermohydraulic performance of finned-tube supercritical carbon dioxide (sCO(2)) gas coolers operating with refrigerant pressures near the critical point. A distributed modelling approach combined with the epsilon-NTU method has been developed for the simulation of the gas cooler. The heat transfer and pressure drop for each evenly divided segment are calculated using empirical correlations for Nusselt number and friction factor. The model was validated against test results and then used to investigate the influence of design and operating parameters on local and overall gas cooler performance. The results show that the refrigerant heat-transfer coefficient increases with decreasing temperature and reaches its maximum close to the pseudocritical temperature before beginning to decrease. The pressure drop increases along the flow direction with decreasing temperature. Overall performance results illustrate that higher refrigerant mass flow rate and decreasing finned-tube diameter lead to improved heat-transfer rates but also increased pressure drops. Design optimization of gas coolers should take into consideration their impact on overall refrigeration performance and life cycle cost. This is important in the drive to reduce the footprint of components, energy consumption, and environmental impacts of refrigeration and heat-pump systems. The present work provides practical guidance to the design of finned-tube gas coolers and can be used as the basis for the modelling of integrated sCO(2) refrigeration and heat-pump systems.