A project is underway to develop R290 low charge heat pump solutions for apartment buildings.
The aim is to replace gas and oil heating systems in existing homes. The Fraunhofer Institute for Solar Energy Systems (ISE) plans to focus on heat pumps that rely on natural refrigerants like propane (R290).
Head of the department of heating and refrigeration at Fraunhofer ISE. Dr. Ing. Lena Schnabel, said Germany needs standardized heat pump solutions for the housing industry to replace gas and oil heating systems acriss all applications.
“Propane has become a recognized refrigerant for the heat pump industry and is now widely used for heat pumps installed outdoors. What we need now are solutions that can be easily implemented indoors as well," Schnabel said.
The project has a budget of $10.9 million (7 million euros) provided by the German Federal Ministry of Economic Affairs and Climate Action. Solutions will be developed for three heat pump applications: single-story heating systems, central heating systems installed inside and outdoors; heat pumps in higher performance classes.
If propane-based heat pumps are to be used as a replacement for single-story gas heating systems or gas and oil-based central heating systems in the basement, special safety requirements would have to be observed for filling volumes above 150 grams. Already, the Fraunhofer ISE project team has demonstrated that a heating capacity of 7 to 10 kilowatts can be achieved with less than 150 grams of the refrigerant propane in the "LC150" project.
This result is the basis for their implementation in a single-story heating concept, in which suitable storage and sources are also being developed as part of the project.
Solutions for the connection to the hydraulic and source systems as well as suitable controls are being developed and demonstrated in the laboratory with the support of heat pump manufacturers and the housing industry.
To replace the central heating system located in the basement, heat pumps with a higher capacity are to be developed. The results from the "LC150" project will be used to transfer the refrigerant reduction to larger capacities. In addition, concepts for the interconnection and control of several heat pumps will be investigated and safety concepts will be identified and tested.
Outdoor heat pump systems with higher capacities are also optimized with a focus on refrigerant reduction, optimized defrosting and evaluations by standardized safety tests. The aim is to be able to implement larger outputs with the same footprint and safety zone through refrigerant reduction and improved defrosting, thus facilitating the installation of these systems in urban areas.
Project leader Dr. Katharina Morawiez said participating companies will have access to all project and measurement results during the project period, as well as indirect use of the test facilities and the experience of Fraunhofer ISE in dealing with propane. Ideally, the development advantage for the participating manufacturers is additionally secured by industrial property rights (patents, utility models, design protection).
She said direct communication between several heat pump manufacturers and the housing industry allows solutions to be developed in a practical manner and thus implemented more quickly, which accelerates the overall ramp-up to higher unit numbers.
