由赵晓璇、何宇佳等撰写的论文Long-term performance evaluation of CO2 heat pump water heater under different discharge pressure control strategies在Applied Thermal Engineering 2023年第222卷在线发表。CO2热泵热水器长期运行的部件性能衰减使排气压力偏移最优，高压控制方式的差异带来了不同程度的COP额外损失。本文针对CO2热泵热水器系统仿真模型，选取8种控制策略，通过引入衰减因子，进行了全工况COP、APF额外损失的对比研究，以评估不同控制策略应对长期运行衰减的鲁棒性。

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论文摘要：

CO2 heat pump water heater has raised considerable attention as an environmentally efficient technology for hot water production. However, after long-term operation, the deterioration of component performance will not only directly cause system performance degradation, but also lead to a deviation of discharge pressure from the actual optimum under different discharge pressure control strategies, further resulting in additional performance loss. So far, the additional performance loss in the long run has not been in-depth investigated. In this study, based on a validated system model of CO2 heat pump water heater with component performance degradation factors, the long-term additional loss of system performance under eight different discharge pressure control strategies are compared. The results reveal that additional performance loss in the long-term operation can be significant under certain control strategy and working conditions. As for the investigated system, the control strategy with the parameter group of ambient and gas cooler outlet temperatures is favorable for application under the nominal operating condition with long-term degradation of heat exchangers, and the average additional loss of COP (coefficient of performance) can be decreased to 0.62%. As for the compressor degradation, the optimal refrigerant charge management strategy is preferred with an average COP loss as low as 0.05% under certain working conditions. In facing with year-round performance degradation, the control strategy with the parameter group of evaporating temperature and gas cooler outlet temperature shows better robustness, since the average additional annual performance loss can be reduced to only 2.52%.