Selection for the use of an axial or centrifugal compressor in a high-temperature heat pump according to the Cordier diagram

Kurzfassung

In order to reduce the effects of climate change on the environment and the public, it is essential to take actions that will counteract the impacts. An important driver of climate change is the CO2 emission of the industrial sector and the resulting heat demand, which is still predominantly covered by fossil energy sources. In order to enable a progressive decarbonization of the industry, an electrified supply of required heat demand by high temperature heat pumps (HTHPs) is a promising approach for the future. In order for these HTHPs to reach a temperature of up to 300 °C, the use of suitable high-performance compressors is required. At the Institute for Low-Carbon Industrial Processes, turbo compressor technology that has established in aerospace engineering is used in two HTHPs pilot plants. Since the working medium and the application of the HTHPs can vary, the selection of the appropriate turbo compressors is needed for their design process and suitable efficiencies. The current presentation focuses on the selection of an axial or radial compressor stage based on the Cordier diagram. In this process, quantities from the HTHP design, are used as input for the calculation of the speed and diameter parameter, and value variations are set up for a wide range. These quantities are the temperature lift, the rotational speed as well as the volumetric flow. In a next step, the design size is also considered and, by converting the specific head and the temperature lift, the suitable working medium. This range of parameters is analysed in the Cordier diagram to enable a selection between axial and radial compressors.