Fraunhofer ISE said on October 7 that it had built a high-temperature heat-pump test rig under the FernWP project, which examines the use of heat pumps to replace coal combustion in district and process heat. Large heat pumps reach their required operating points when components, controls, hydraulic integration and operating strategy are properly designed and implemented.
The rig can measure heat-pump performance at temperatures up to 160 °C. Researchers used it to analyse process steam production at up to 160 °C and pressurised hot water.
Fraunhofer ISE has collected operating data since 2023 from five large heat pumps in district-heating networks under a separate project. Axel Oliva, the project manager, said the monitored pumps can reach their intended operating points, but efficiency and availability also depend on the heat source, hydraulic integration, the existing generation system and the operating strategy.
Thermal output declined for installations drawing heat from flowing water during part-load operation and when heat-source temperatures fell below approximately 6 °C. The same monitoring found that large heat pumps are increasingly operated around daily demand profiles and energy-market conditions, rather than the predominantly seasonal use envisaged in early plans.
FernWP is examining heat-source availability alongside economic and regulatory conditions while developing and testing a heat-pump prototype, according to the project’s description. Project partner Fraunhofer ISI is compiling an overview of economic conditions for large heat pumps and supporting analyses of high-temperature heat pumps for industrial process heat, according to its account of the work. The joint project is scheduled to run through September 2027, according to Fraunhofer ISE.
