Abstract
In recent years, the issue of sustainability, especially in terms of resource utilization, has become increasingly prominent. In contrast, even today a large part of the process heat required in industry is obtained by burning fossil fuels. In order to meet this demand sustainably, the development of high-temperature heat pumps has steadily increased in recent years. Nowadays, heat pump systems are mostly commercially available up to a temperature level of 90 °C. Even taking into account the few demonstration pilot plants up to temperature levels of 160 °C, there is a certain gap up to 200°C which would by needed for a variety of industrial applications. To overcome this gap and their experimental evidence the DLR has designed the pilot plant ZiRa. In this paper, the construction of the plant and the steady state simulation results are presented. Based on the reversed Rankine cycle the pilot plant is able to lift the temperature from 120 °C at source to 200 °C at the sink with a COP of 3.4. This is achieved by a three-stage compression. The compressors are described by their respective performance maps, which are used to investigate the operating range of the plant by varying the source temperature between 100 °C and 130 °C. In addition, the performance of the system was investigated in relation to the compressor part-load range. It has been shown that even with small changes in the respective compressor speed, the performance varies in terms of discharge pressure and sink temperature. Finally, the start-up procedure of the pilot plant is described.
