A coupled seawater air-conditioning system for simultaneous heating and cooling: Impacts analysis and hybrid mode-switching strategy

Coupled seawater air-conditioning systems for simultaneous heating and cooling have attracted attention due to their energy savings and sustainability. In such systems, cooling and heating subsystems are coupled via seawater-based heat recovery to enhance overall system performance. However, existing studies have not quantitatively analyzed the performance of coupled seawater air-conditioning systems under different seawater-based heat recovery modes, and an energy-efficient operation strategy for dynamic mode switching is still lacking. To address these issues, this study investigates a coupled seawater air-conditioning system consisting of chillers and heat pumps for simultaneous heating and cooling. A comprehensive analysis quantifies the effects of seawater temperatures, coupling modes, and ratios of cooling to heating load on system power consumption. Based on the analysis, a hybrid mode-switching strategy integrating knowledge-guided and model-based decisions is proposed, aiming to minimize the system’s power consumption. Results show that the optimal coupling mode depends jointly on seawater temperatures and ratios of cooling to heating load: Mode #A1 is optimal at low seawater temperatures, Mode #A2 is optimal at high seawater temperatures, and at medium seawater temperatures, the optimal mode varies with ratios of coolng to heating load. The proposed hybrid mode-switching strategy dynamically switches between coupling modes, reducing annual system power consumption by up to 6.47% compared with the independent mode (Mode #0), and by up to 4.88% compared with the conventional coupling modes (Modes #A1 and #A2). This study quantifies the key factors governing the performance of coupled –seawater air-conditioning systems and proposes a computationally light operation strategy for energy-efficient operation, contributing to the sustainable urban energy transition in coastal areas.