High-temperature heat pump with integrated storage

The “BREAD” project (High-Temperature Heat Pump with Integrated Storage – reversed BRayton cycle for combined hEAt and colD) addresses the development of a system for providing heat and cooling on a sub-megawatt scale. It can provide industrial process heat in the range of 250 °C to 400 °C as well as process cooling at 5 °C and colder. Objective: To combine heat pump, heat exchanger and storage technologies into an integrated system for industrial electrification.

At the heart of the project is the development of a high-temperature heat pump based on a reversed Brayton cycle. To this end, a prototype with the following specifications will be designed, built, and tested in the laboratory: thermal output of approximately 150 kW, modulation range between 100 and 150 kW, maximum electrical power consumption of 100 kW, and cooling capacity of approximately 30 kW. The prototype is intended to provide process heat at 250 to 300 °C as well as cooling in the range of 0 to 5 °C and achieve a COP of 1.3 to 1.5.

In addition, the project is developing a high-temperature heat storage system for temperatures up to 400 °C and a cold storage system for temperatures down to -15 °C. The storage systems are designed to enable cold starts, support load shifting, and accommodate dynamic operating modes.

The overall system is being designed and optimized for industrial production and specific market applications (for example, in the food industry, in bakeries, or in drying processes). Analyses of environmental, social, and techno-economic feasibility complement the technical development.

The decarbonization of industrial process heat is key to achieving climate neutrality by 2050. While electric heat pumps are already used in many applications, today’s high-temperature compression heat pumps face technical limitations at higher temperature ranges. Typically, they are limited to supply temperatures of up to 200 °C and simultaneously require suitable heat sources at sufficiently high temperature levels. Industrial processes with higher temperature requirements are therefore often still supplied with fossil fuels or via direct electric heating.

The “BREAD” system overcomes this challenge by enabling large temperature differences while simultaneously providing both heat and cooling. The intelligent combination of a heat pump, heat exchangers, and thermal storage units creates a flexible energy system that supports load shifting and can better accommodate operating conditions in industrial processes.

A key feature: The system combines high-temperature heat generation and cooling in an integrated approach. Compared to separate provision via direct electric heating and conventional compression refrigeration systems, the “BREAD” system is expected to operate 30 to 50 percent more efficiently. In this way, the project supports the electrification of industrial processes and enables the use of green electricity as the primary energy source.

• Fraunhofer Institute for Solar Energy Systems ISE, Germany
• MITIS SA, Belgium
• University of Mons, Belgium
• KTH Royal Institute of Technology, Sweden
• MG Sustainable AB, Sweden
• IWS-Monjé Heat Exchangers GmbH, Germany