Optimal partial-load operation strategies of surface water-source centrifugal heat pumps with thermal energy storage for large buildings

Surface water-source heat pumps (SWHPs) are promising solutions for sustainable heating and cooling in large office buildings. However, the partial load performance of SWHPs with centrifugal compressors and thermal energy storage (TES) has been reported sparsely. This study proposes an optimal operating strategy for SWHPs with centrifugal compressors and TES to enhance energy efficiency and reduce operating costs by optimizing partial-load operations in large office buildings. Dynamic simulations are conducted to analyze operational scenarios considering the building load ratio, water temperature, and maximum partial load ratio (PLR). A novel PLR–limiting strategy was proposed (TPSC) to reduce energy consumption compared to the full-load operation strategy (TFSC). Furthermore, the TPSC was optimized using artificial neural networks and a multi-objective genetic algorithm to determine optimal PLR settings and TES temperatures. The optimized TPSC strategy (TPSCo) achieved a maximum nighttime power consumption ratio of 80.4%, compared to 66.7% and 68.4% for the TFSC and TPSC strategies, respectively. Accordingly, the TPSCo reduced overall operating costs by 16.8% compared to the TFSC, and by 9.3% compared to the TPSC, while maintaining comparable energy consumption. These findings demonstrate that the TPSCo delivers superior energy efficiency and cost-effectiveness, highlighting the potential of advanced SWHP strategies as sustainable heating and cooling solutions for large office buildings.