A new type of district heating system based on distributed absorption heat pumps

Large district heating (DH) system accounts for 70% of urban building heating in China. In North China, this proportion is even higher (The North China is the north of the Huai River and Qinling Mountains). Many cities in North China can exploit various kinds of low-grade renewable energy. This paper presents a new heating method to realize renewable energy recovery by absorption heat pumps associated with municipal network. In the DH substations, absorption heat pumps are driven by the exergy-difference originated from the larger temperature difference of heat exchange between primary and secondary heat network. There are two configurations-type I and type II substations based on the temperature of renewable energy. A reasonable parameter setting of system is suggested. The equipment operational performance was optimized based on a practical example. The low-grade renewable energy can be recovered effectively in this method. As a result, both heating capacity and energy efficiency of the DH system can be improved. Furthermore, operating costs may be reduced remarkably, due to the reduction in both the coal consumption of heat production unit and the power consumption of delivery pump. Therefore, the system is superior in energy conservation and has a promising application prospect. -- Highlights: → In this paper, a novel heating system is proposed to recover the low-grade renewable energy. → A novel heating system is proposed to recover the low-grade renewable energy by the technique of hot water absorption heat pump in the substation of DH system. → Two types of substations are proposed based on the temperature difference of low-grade thermal fluid. → Comparing to conventional DH system, the new heating system can save energy by 23-46%. → This approach can greatly reduce the primary energy requirements and associated operational costs. → The problem of matching and regulation of the new system are analyzed.