二氧化碳热泵热水器充注量的不动点优化

Optimization of Refrigerant Charge in Transcritical CO_(2) Heat Pump Water Heater

二氧化碳跨临界循环应用于热泵热水器具有供水温度高、能效高的优点,而最优高压控制是保证其高能效的关键之一。为了避免实际系统最优高压控制的复杂性,提出通过系统设计实现最优充注量近似不变的充注量不动点优化方法,可避免最优高压控制,在保证系统高能效运行的同时极大地简化了系统控制。仿真计算表明,通过调节换热器大小并在气体冷却器出口添加高压储罐,可以使不控高压系统的平均能效衰减减小至-0.8%。

Transcritical CO2 cycle can achieve high water supply temperature and high energy efficiency when applied in heat pump water heater.However,the optimal high pressure control is crucial to system efficiency.To avoid the complexity of pressure control in practical applications,we proposed the optimization methods of refrigerant charge to approach optimal high pressure.Through system design,the optimal refrigerant charge remains approximately constant,which greatly simplifies the system control and ensures high efficiency.The simulations show that by resizing heat exchangers and adding refrigerant reservoir,the average COP loss of system without pressure control can be reduced to-0.8%.