Investigation on Process Architectures for High-Temperature Heat Pumps Based on a Reversed Brayton Cycle

Kurzfassung

Heat pumps are a core technology for the decarbonization of industrial process heat. High-temperature heat pumps (HTHP) typically upgrade waste heat of industrial processes. This way they can simultaneously electrify process heat and reduce the respective primary energy consumption. The utilization of renewable electricity to drive HTHP additionally results in decarbonization of process heat supply. Commercial industrial heat pumps supply process heat at temperatures up to approximately 150°C. However, several studies have shown that process heat can be also supplied with HTHP at temperatures above 150°C. The economic and environmental performance of HTHPs depend strongly on their process architecture and their integration into the industrial process they supply with heat. This paper focuses on the investigation of high-temperature heat pump process architectures based on the reversed Brayton cycle with air as the working medium. The process architecture of the HTHP pilot plant at the Institute of Low-Carbon Industrial Processes of the German Aerospace Center (DLR) is presented and used as a reference. The current work investigates the heat source and heat sink integration in the heat pump cycle architecture and methods to effectively break down the compression and expansion processes to optimize performance for a heat sink temperature of 250°C. To analyze and compare the results, fixed boundary conditions valid for all architectures are made.