带约束条件的CO2热泵热水系统高压控制方程

摘要

The optimization and control of discharge pressure is important in transcritical CO2 heat pump water heating systems.The traditional high-pressure control equation simply takes the exit temperature of the gas cooler into account,neglecting the impacts of the pinch point and the outlet temperature of water,which might lead to a huge coefficient of performance (COP) loss in applications.In this paper,we report the development of a constrained gas cooler model by considering the influence of the pinch point and water inlet and outlet temperatures.The main impact factors of the optimum high pressure are determined through the design of experiments and statistical methods.Consequently,a new constrained optimal high-pressure control equation using least-squares regression is proposed.Based on the new control equation,the system COP loss is 1.8％ in average(maximum 8.7％),providing better reliability for engineering practices.%系统高压的优化与控制在提升跨临界CO2系统效率方面至关重要.在CO2热泵热水系统中,传统的高压控制方程中仅考虑了气体冷却器侧的出口温度而忽略实际应用中对出水温度的要求和温度夹点,导致系统性能大大降低.本文针对温度夹点和进出水温等约束的影响,建立了有约束的气冷器模型,并对系统高压进行了优化.采用实验设计以及统计学方法确定影响最优高压的主要因素,通过最小二乘法回归出最优高压控制方程.使用该高压控制方程的系统平均COP损失1.8％,最大COP损失8.7％,可以更好地满足实际应用.