Performance evaluation of industrial heat pump based on reversed Stirling cycle for ultra-high temperature applications
This paper presents comprehensive test results and performance evaluation of a 400-kW industrial heat pump operating on the reversed Stirling cycle. The system uses helium (R704) as the working fluid and can deliver heat at temperatures up to 200°C. Performance data collected from multiple installation sites in the food and pharmaceutical industries demonstrate the system's capabilities across various operating conditions. The heat pumps have been operated with source temperatures ranging from 15°C to 68°C and sink temperatures ranging from 134°C to 199°C, corresponding to temperature ratios from 1.25 K/K to 1.55 K/K. Carnot efficiency is found to be a function of temperature ratio, and the heating capacity does not vary with the source temperature. The heat pumps have been operated for 15 000 hours in varying operating conditions, but the performance has been evaluated for periods with nearly steady operating conditions, in total 8 000 onehour periods of steady conditions. Results show significant efficiency advantages compared to conventional technologies for high temperature lifts. The measured performance data closely match simulation model predictions, validating the theoretical approach used for system design.