Numerical investigation on operational performance of seawater-source heat pump system coupled with capillary-box heat exchangers

In view of the energy-saving potential of the seawater-source heat pump system (SWHPs) coupled with capillary-box heat exchangers (CBHEs), the operational performances of this system were investigated on various temporal scales, including annually, monthly, and daily. An overall system numerical model was developed by integrating the CBHEs, heat pump and dynamic building loads model. The results indicated that the annual COPh was 3.4. In the coldest month, the monthly COPh was 3.3, and the daily COPh was mainly determined by the daily heating demand. The corresponding annual COPc was 4.8. In the hottest month, the monthly COPc was up to 5.0, and the daily COPc was more sensitive to seawater temperature fluctuations. On a typical summer day, the operating time of the heat pump with an hourly capacity ratio above 50 % was about 2.7 times that of a typical winter day. Due to the effective removal of the heat discharged from the CBHEs in the seabed, the impact of heat accumulation on the performance of this system can be neglected in the long-term operation. This study provided practical implications for the design and application of the CBHEs-coupled SWHPs.