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• An unsteady state model of seawater heat exchanger with wave theory is established. • Thermal performance of the heat exchanger under icing condition is investigated. • Heating performance of SWHP system at various seawater temperature is analyzed. • A macro spatial analysis of SWHP in numerous coastal cities is performed. Seawater-source heat pump (SWHP) system exhibits merits of building energy conservation and reducing carbon emissions, while enhancing the heat transfer of seawater heat exchangers is the key to improve the system performance. Here, a model of SWHP system with staggered tube-bundle heat exchanger is established and its performance in winter is numerically studied and verified by experiments. The wave theory is introduced into the mathematical model to describe the flow field of actual ocean and improve the accuracy. The heat transfer performance of staggered tube-bundle exchanger is investigated under icing conditions, and the results indicate that the ice layer thermal resistance outside the tube accounts for more than 28% of the total thermal resistance. The impacts of seawater temperature on the SWHP system performance are discussed and the average increment of heating capacity and COP is 0.12 kW and 0.046 respectively with the increase of seawater temperature by 1 °C. Furthermore, a spatial analysis of SWHP system in 29 coastal cities of China are analyzed and compared with air-source heat pump (ASHP) system. The results show that SWHP system has greater advantages than ASHP system, especially in the southern cities. This research comprehensively analyzes the technology, economy and geography of SWHP system from a more macro perspective, and it can promote the application of ocean thermal energy. [ABSTRACT FROM AUTHOR]

• An unsteady mathematical model was developed based on wave theory. • The model was validated by the tested results. • Effects of key parameters on the thermal performance were studied. Seawater heat pump system exhibits merits of reducing building energy consumption, while enhancing the heat transfer of seawater heat exchangers is the key to improve the system performance. The effect of seawater flow behavior on the thermal performance of seawater heat exchanger immersed in oscillating flow is significant but often neglected. An unsteady mathematical model was firstly developed to describe heat transfer of oscillating flow around the staggered tube-bundle heat exchanger and verified by experimental results. Effects of the structural and operational parameters, such as the tube length, heat transfer fluid velocity, wave parameters and sinking depth on the thermal performance were analyzed. It was shown that the thermal efficiency of seawater heat exchanger ascended with the increase of wave amplitude and decrease of the heat exchanger sinking depth. Additionally, the tube length and heat transfer fluid velocity could be reasonably designed to achieve the optimum value between cost and performance. The heat transfer mechanism in seawater side was predominated by forced convection to natural convection with the increasing sinking depth under various wave parameters. The proposed model is favorable to delicately characterize the heat transfer of seawater heat exchanger with the consideration of seawater flow. The results in this paper is helpful to guide the optimization on designing the staggered tube-bundle heat exchanger in oscillating flow and to promote the application of ocean thermal energy. [ABSTRACT FROM AUTHOR]