Abstract The characteristics of heat transfer and pressure drop of supercritical CO2 and water in microtube heat exchangers with and without baffles are studied experimentally. The tube bundle of the microtube heat exchanger consists of 37 stainless steel tubes with an inner diameter of 1.6 mm and an outer diameter of 2 mm. The length of the tube is 500 mm. The experiments are divided into hot water–cold water heat transfer experiments and supercritical CO2–water heat transfer experiments. The results of hot water–cold water experiments are shown to produce a large discrepancy with the conventional heat transfer correlation and new correlations of water convective heat transfer coefficient in the shell side are fitted according to the experimental results. The comprehensive performance of the heat transfer and pressure drop of the microtube heat exchanger with baffles is better than that without baffles. The results of CO2–water experiments show that the prediction of the design program based on Dang's heat transfer correlation of supercritical CO2 is relatively in better agreement with the experimental results than others. The overall pressure drop of CO2 in microtube heat exchangers is small. However, the pressure drop at the inlet and outlet of microtube heat exchangers is larger than that of conventional shell and tube heat exchangers. The pressure loss coefficient is modified according to the experimental results.

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超临界CO2与水在微管换热器中对流传热及压降的实验研究

摘要 通过实验研究了超临界CO2 与水在有挡板和无挡板微管换热器中的传热特性和压降特性。微管换热器的管束由37根内径1.6mm、外径2mm的不锈钢管组成。管的长度为 500 毫米。实验分为热水-冷水传热实验和超临界CO2-水传热实验。热水-冷水实验结果表明与常规传热关系式产生较大差异，并根据实验结果拟合了壳侧水对流换热系数的新关系式。有折流板的微管换热器的传热和压降综合性能优于无折流板的微管换热器。CO2-水实验结果表明，基于Dang的超临界CO2传热相关性的设计程序预测与实验结果的一致性较好。微管换热器中 CO2 的整体压降很小。但是，微管换热器进出口压降比传统管壳式换热器大。根据实验结果修改压力损失系数。超临界 CO2 的传热相关性与实验结果的一致性相对较好。微管换热器中 CO2 的整体压降很小。但是，微管换热器进出口压降比传统管壳式换热器大。根据实验结果修改压力损失系数。超临界 CO2 的传热相关性与实验结果的一致性比其他的要好。微管换热器中 CO2 的整体压降很小。但是，微管换热器进出口压降比传统管壳式换热器大。根据实验结果修改压力损失系数。