由何宇佳、成家豪、常萌萌、张春路（通讯作者）撰写的论文Modified transcritical CO2 heat pump system with new water flow configuration for residential space heating在Energy Conversion and Management 2021年第230卷在线发表。论文对于CO2热泵供热系统提出了一种全新的水路结构，显著提升了系统能效，并有效降低了机组成本，对于该类热泵的实际应用具有指导意义。本文工作受国家自然科学基金项目“基于拓扑同胚循环构造与换热器网络化重构的二氧化碳热泵供暖系统原理及应用”的资助。

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论文摘要：

Utilizing air-source heat pumps for residential space heating in cold climates is an important measure for environmental protection and energy conservation. In this paper, a new water flow configuration for water-heating process is proposed for transcritical CO2 heat pump combined with a dedicated mechanical subcooling (DMS) subsystem. In the modified system, the conventional parallel water flow configuration is changed to a new series water flow configuration, in which the CO2 gas cooler is separated into two parts with the condenser of DMS subsystem in the middle. The water is sequentially heated by CO2 gas cooler 1, condenser of DMS subsystem and CO2 gas cooler 2. Through three-stage heating, the uniformity of refrigerant-water temperature difference field is remarkably improved. The evaluations are conducted from energetic, exergetic and economic perspectives. Firstly, the impact of heat transfer area allocation among the three water-heating heat exchangers on system performance is numerically investigated. The results show that the COP of modified system is 1.6%–7.6% higher than that of the existing system. The greater the temperature difference between supply and return water and the higher the ambient temperature are, the more significantly the COP increases. By evaluating heating seasonal performance in three typical cities, energy efficiency of the modified system is increased by 2.4%–6.5%. Besides, the exergy efficiency is also improved by 2.1%–6.6%. As for life cycle cost, the proposed system can save up to 3.7% investment in terms of annual operation.