Numerical Investigation and Design of a Test Stand for a High Temperature Heat Pump up to 200 °C
High-temperature heat pumps (HTHPs) are essential for improving the efficiency of industrial heating processes. Increasing the HTHP supply temperatures can enable a broader impact of the technology on different industrial sectors, but also has challenges associated with cycle efficiency, compression technologies, and material compatibilities. This study presents the modeling efforts to design and develop a state-of-the-art test facility with a novel HTHP architecture with the goal of producing heat at 200 °C with a subcritical cycle. Specifically, the cycle features refrigerant economization coupled with internally cooled rotors in an additively manufactured twin-screw compressor for enhanced discharge temperature control and efficiency. Potential refrigerant candidates were filtered based on a previous refrigerant screening and the refrigerant that yielded the best results was pure cyclopentane. Increased model fidelity was achieved by integrating a compressor map and segmented heat exchanger models, resulting in a predicted system COP of 2.85, Second Law efficiency of 48.7%, and an outlet heat sink temperature of 201 °C. The numerical investigations have been employed to design the test stand that will be used to validate the cycle’s performance and to demonstrate safe operation with cyclopentane. The test setup will confirm the ability to reach 200 °C heat sink temperatures, assess refrigerant and lubricant compatibility, and explore compressor behavior and material compatibility at high temperatures. This integrated work demonstrates the feasibility of this cycle architecture and supports its role in maximizing HTHP efficiency for industrial applications.