Heat exchangers for cooling supercritical carbon dioxide and heat transfer enhancement: A review and assessment
Heat exchangers for cooling supercritical carbon dioxide and heat transfer enhancement: A review and assessment
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DOI：
10.1016/j.egyr.2021.06.089
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发表时间：
2021-11
期刊：
影响因子：
5.2
通讯作者：
Wenguang Li;Zhibin Yu
中科院分区：
文献类型：
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作者：
Wenguang Li;Zhibin Yu
超临界和跨临界二氧化碳循环广泛应用于冰箱、热泵和发电厂，换热器是其中的关键部件。本文对超临界二氧化碳(SCO2)冷却流动换热器的研究现状进行了综述。在SCO2流动中，CO2接近其临界点，由于热物性的剧烈变化，有可能导致换热恶化或强化。首先，重点介绍了SCO2的传热特性。其次，详细分析了SCO2换热器的换热特性，包括实验、CFD模拟、动态响应以及SCO2换热器的设计。第三，对SCO2强化换热进行了总结。提出了一种表征SCO2热物性和传输性常数随温度变化的方法，并根据性能评价准则和强化效率以及MatLab优化方法对可能适用于SCO2换热器设计的强化传热方法进行了评价和选择。结果表明，用高斯概率密度函数的多项式可以从数学上反映SCO2的热物性常数随温度的变化，可用于SCO2换热器的设计和热力响应分析。在雷诺数Re=1.9×104~2.55×105的条件下，采用凸出法、粗单元法、扭带插入法和纳米包覆法可能是更适合于SCO2的强化换热方法，但尚需数值和实验验证。为工程中SCO2冷却换热器的设计、优化和实验提供了初步指导。
Supercritical and trans-critical carbon dioxide cycles are widely used for refrigerators, heat pumps and power plants, of which the heat exchangers are key components. This article presents a critical review of heat exchangers for cooled supercritical carbon dioxide (SCO2) flows, within which CO 2 is close to its critical point and thus is likely to experience heat transfer deterioration or enhancement due to the dramatical change of thermo-physical properties. First, SCO2 heat transfer features were highlighted. Second, SCO2 heat transfer characteristics in heat exchangers were analysed in detail, including experiment, CFD simulation, dynamic response, and design of SCO2 heat exchanger. Third, SCO2 heat transfer enhancement was summarized. An approach for representing SCO2 thermo-physical and transport property constants versus temperature was proposed, and the heat transfer enhancement methods which may be potentially applicable to SCO2 heat exchanger design were assessed and selected according to performance evaluation criterion and enhancement efficiency as well as MATLAB optimization. It was demonstrated that a polynomial of Gaussian probability density function can reflect the variation of thermo-physical property constants of SCO2 with temperature mathematically and may be used in SCO2 heat exchanger design and thermal dynamic response analysis. When a SCO2 cooling heat exchanger works at Reynolds numbers R e= 1. 9× 10 4-2.55× 10 5, the protrusion, rough element and twisted tape insert approaches as well as nano-coating methods may be more suitable heat transfer enhancement methods for SCO2, but numerical and experimental confirmation is desirable. A preliminary guidance to design, optimization and experiment of SCO2 cooling heat exchanger for the project is offered.