Veröffentlichungen

In recent years, the use of industrial waste heat as a heat source for high-temperature heat pumps has become increasingly important [1], [2]. In order to analyze further applications in the district heating sector, this paper deals with a parameter study. In the district heating sector, the flow and return temperatures in existing networks are gradually lowered, e.g., to reduce heat losses. District heating systems cannot then supply consumers with higher temperatures (e.g., above 120 °C). The possibility of using the flow or return flow as a heat source also offers potential for high-temperature heat pumps. District heating operators can then take over the assignment of process heat supply or develop new customers. Numerous influencing variables (such as different refrigerants, circuits, heat source temperatures) affect the heating capacity or efficiency of high-temperature heat pumps. Therefore, it is important to find an optimal heat pump solution for the respective boundary conditions. To solve this problem, various refrigerants have been investigated, including natural refrigerants (R600, R601a, R744), HFO refrigerants (R1234ze(E), R1336mzz(Z), and HCFO refrigerants (R1224yd(Z), R1233zd(E)). Furthermore, improvements in the process can be achieved by modified circuits (e.g., internal heat exchanger, two-stage compression and intercooling with two-stage expansion). The heat pump inlet temperature on the source side is 50 to 100 °C. The target temperature of the heat supply is 140 °C (e.g., steam supply). All systems were modeled and simulated using the EBSILON®Professional program [3]. In the investigations, the COP was determined as an essential parameter. This in turn allows an optimal preselection of heat pumps. These systematic investigations show the functional progression of the COP, which promotes a better understanding of the problem. The results provide information for the district heating sector and industry to promote the use of high temperature heat pumps in district heating areas.

Schlagwörter: Process heat, heat pump, district heating, simulation, parameter study