Application and analysis of an air–wastewater dual-source heat pump cooperative thermal energy storage system for bathhouse buildings in severe cold regions

In response to the national strategy for energy conservation and emission reduction, and to enhance the efficiency of clean energy utilization, this study focuses on a public bathhouse of an industrial and mining enterprise located in Wuhai City, a severely cold region. Addressing the challenges of high energy consumption, excessive carbon emissions, and insufficient thermal comfort in the original system, a novel air-source–sewage-source dual-source heat pump system with coordinated energy storage is proposed and constructed. A system model is developed in TRNSYS, in which the air-source heat pump serves as the primary heat source and the sewage-source heat pump as the auxiliary heat source. Combined with a large-scale thermal storage tank and a time-of-use electricity pricing regulation strategy, the system achieves “peak shaving and valley filling” by storing energy during off-peak hours and releasing it during non-off-peak hours. Simultaneously, sewage waste heat recovery and thermal storage buffering are employed to improve system adaptability under low-temperature and load-fluctuation conditions. Simulation and experimental results demonstrate that the system can save approximately 414,400 kWh of electricity annually, reduce operating costs by about 253,800 CNY, cut CO₂ emissions by roughly 291.12 t, and significantly improve users’ thermal comfort. The findings indicate that the dual-source coordination and intelligent energy storage regulation model not only offers remarkable energy-saving and emission-reduction benefits as well as strong economic performance, but also shows broad prospects for engineering application and promotion in public bathhouses of industrial and mining enterprises in severely cold regions.