Abstract:

As a new type of high-efficiency micro-channel heat exchanger, printed circuit heat exchanger (PCHE) has great potential for its application in floating LNG storage and gasification unit (FSRU). The flow and heat transfer characteristics of supercritical methane in the PCHE channel were simulated. The simulation results show that the heat transfer coefficient first increases and then decreases with temperature, and reaches a peak near the pseudocritical temperature (202—212 K). The pressure drop first remains unchanged with the temperature, then rises sharply near the pseudocritical temperature, and then increases with the temperature. When the temperature is near the pseudocritical temperature, increasing the heat flux under low mass flux density will deteriorate heat transfer coefficient. The heat transfer coefficients under different pressures all reach the peak at the pseudocritical temperature under each pressure. When the temperature is lower than the pseudocritical temperature, the influence of pressure on the pressure drop is negligible, and when the temperature is higher than the pseudocritical temperature, the pressure drop increases with the pressure. When the pressure is increased from 6.4 MPa to 8.5 MPa, the heat transfer coefficient is reduced by 32.5% and the pressure drop is reduced by 28.5%. The average errors of the developed heat transfer and pressure drop correlation equations are 5.6% and 4.2%, respectively.

Key words: supercritical methane, printed circuit heat exchanger, pseudocritical temperature, numerical simulation, flow, heat transfer

摘要：

印刷电路板式换热器（printed circuit heat exchanger，PCHE）作为一种新型高效微通道换热器，将其应用在LNG浮式储存与气化装置（FSRU）上具有非常大的潜力。对超临界甲烷在PCHE通道中的流动和传热特性进行了数值模拟，结果表明：传热系数随温度先增大后减小，并在准临界温度（202～212 K）处达到峰值；压降随温度先保持不变，然后在准临界温度附近急剧上升，之后随温度增大的趋势变缓；当温度在准临界温度附近时，低质流密度下增大热通量会恶化传热；不同压力下传热系数均在准临界温度处达到峰值；温度低于准临界温度时，压力对压降的影响可以忽略，温度高于准临界温度时，压降随压力增大而显著降低；压力由6.4M Pa提高到8.5 MPa时，传热最大降低32.5%，压降最大降低28.5%；开发的换热和压降关联式平均误差分别为5.6%和4.2%。

关键词: 超临界甲烷, 印刷电路板式换热器, 准临界温度, 数值模拟, 流动, 传热