Abstract: There are two serious problems in the combined heat and power system: with the increase of heating area and quality, the heating is insufficient; the heavy discharge of low-grade thermal energy in the circulating cooling water wastes energy seriously. A novel system is presented based on ejector heat pumps (EDH-CHP) to solve the two problems by improving the heating capacity of the district heating system. It recycles the waste heat from circulating cooling water for district heating, and increases the heating capacity of the existing heating network by increasing the temperature difference between the water streams supplying and returning the original heating network. Compared with a traditional system, the new one has an additional ejector heat pump in the heating station, named HP1, and another ejector heat pump in the heating substation, named HP2. Thermodynamic analysis and experimental study are carried out for the two ejector heat pumps. The results show that both HP1 and HP2 can improve the performance of district heating under normal working conditions. Experimental results show that the COP of HP1 can reach 1.4—1.9 and the temperature of returning water in the original network can be decreased to 35℃ in HP2. A typical case study shows that the EDH-CHP system can improve the heating capacity of the existing heating network by 50% by adding 30% steam consumption, or improve the heating capacity of the existing heating network by 9% at the same steam consumption, or decrease the energy consumption by 6% at the same heating capacity.

Key words: design, district heating, ejector heat pump, recovery, experimental validation

摘要： 热电联产面临着两个严重问题：供热面积与质量的增加导致供热不足；电厂凝汽器循环冷却水存在大量低品质热量浪费。为同时解决这两个问题，提出了一种利用喷射式热泵强化集中供热的新型EDH-CHP系统。该系统从循环冷却水中回收余热，并将余热应用于集中供热；另外通过增大供热一次网的供回水温差提高原一次网的供热能力。与原系统相比，新型系统在热力首站和热力站分别增加一台喷射式热泵（HP1、HP2）。分别对两台喷射式热泵进行热力学分析及性能实验研究。分析结果表明：HP1和HP2均能有效提高系统性能。实验结果表明：HP1的COP可达1.4～1.9，HP2可降低一次网回水至35℃。经典案例分析表明：新型系统可增加50%供热能力或减少6%能源消耗。

关键词: 设计, 集中供热, 喷射式热泵, 回收, 实验验证