高温CO_2热泵套管式气冷器的仿真与优化设计

Simulation and Optimal Design of Tube-in-tube Gas Cooler for High-temperature CO_2 Heat Pump

以Petrov换热关联式为基础,建立了CO_2气冷器的数值仿真模型,并根据实验数据对模型进行了修正,并通过联立拟合的压缩机模型,分析了CO_2系统在不同工况下,排气压力、气冷器单管长度和并联管程数对其性能的影响:给定气冷器布局,最优排气压力随供水温度上升而升高;给定工况下,气冷器CO_2出口温度随着排气压力升高而降低,而热水流量和制热量都会增加;不同工况下,当排气压力低于最优压力时,管长的增加对系统COP值增大的影响非常显著;在供水温度低于70℃时,并联管程数的增加使系统的COP值增大,但高于70℃时,并联管程数多的系统COP值反而更低。

Based on the Petrov model for supercritical CO2 heat transfer, a numerical model for gas cooler was developed and then corrected according to the experimental data. By combining the fitted compressor model, the effect of discharge pressure, single tube length and tube passes on the system performance under different operating conditions was investigated： for a given gas cooler configuration, the optimal discharge pressure increased with increasing hot water supply temperature; Given the operating condition, the gas cooler CO2 outlet temperature decreased, hot water flow rate and heat capacity increased as the discharge pressure increased; The trend of increasing COP with increasing tube length before approaching the optimal discharge pressure was much more significant than that exceeding the optimal discharge pressure under different operating conditions; A larger COP was achieved by increasing tube passes when the hot water supply temperature was set below 70℃, as opposed to that at a hot water temperature higher than 70℃.