Fraunhofer ISE optimizes propane heat pump technology

• Together with heat pump manufacturers and suppliers, the Fraunhofer research project LC150 ("low charge 150 g") has set itself the goal of researching a standardized and refrigerant-reduced refrigeration circuit using propane.
• The Fraunhofer Institute for Solar Energy Systems (ISE) has now developed a functional heat pump functional pattern with the climate-friendly and cost-effective alternative propane.
• For the research series, Kelvion has provided condensers for a refrigeration circuit with the ConBraze type GK108H plate heat exchanger.

With the Green Deal, the EU has committed itself to becoming CO2 neutral by 2050. In Germany alone, the provision of heating and cooling makes up 40% of total final energy consumption. Efficient and sustainable key technologies, such as heat pumps, are therefore becoming increasingly important in driving the energy transition. The focus is on natural refrigerants, as it is highly likely that only such refrigerants as propane will be allowed to be used throughout the EU in the future. All conventional fluorinated hydrocarbons (PFAS) will no longer be available to the market.

The LC150 research project of the Fraunhofer Institute for Solar Energy Systems (ISE), funded by the German Federal Ministry for Economic Affairs and Energy (BMWi), set itself the task of researching a standardized and refrigerant-reduced refrigeration circuit with propane together with heat pump manufacturers and suppliers. During the project, which has now been completed, the researchers and a consortium of heat pump manufacturers developed a refrigerant-reduced propane heat pump. Kelvion’s GK108H brazed plate heat exchanger was part of a test series.

Less propane, more safety

Propane is a particularly promising refrigerant because it exhibits comparable refrigeration performance to conventional refrigerants, features very good thermodynamic properties and low global warming potential (GWP). Many heat pump manufacturers now offer propane heat pumps, but usually only for outdoor installation. However, propane is highly combustible. Reducing the refrigerant to below 150g is a promising way of minimizing the risk of fire. This approach corresponds to the currently valid specifications of the regulations. According to the current product safety standard DIN EN 60335-2-40:2014-01, flammable refrigerants can be used indoors with lower capacities and a refrigerant charge of up to 152 grams. Fraunhofer ISE has investigated in more detail how this can be achieved.

In a series of tests with heat exchangers, commercially available units with low filling volumes were selected. A key component of the concept is the use of heat exchangers operating with minimal refrigerant use. Kelvion's GK108H was used in heat pump pilot plants that performed very well in the tests and was also part of the two final best-of refrigeration circuits.

The GK108H is part of the ConBraze series and features a new plate design, low fill volume, high efficiency and thermal performance. "With these features, the ConBraze series more than meets the ever-increasing demand for environmentally friendly, energy-efficient cooling and heating systems, as resources are consistently conserved during both the production and ongoing operation of these units," says Matthias Funke, Head of R&D at Kelvion's Nobitz-Wilchwitz site. "New types of vortex cells enable improved heat transfer and thus increased efficiency by generating higher turbulence in the duct. Thus, the units are ideal for the smallest space requirements and highest efficiency."

More heat pump solutions: https://pages.kelvion.com/hx_heatpump_solutions/

About Fraunhofer ISE

The Fraunhofer Institute for Solar Energy Systems ISE in Freiburg is the largest solar research institute in Europe. Approximately 1400 employees work towards a sustainable, economical, secure and socially just energy supply system based on renewable energies. Fraunhofer ISE contributes to this with the research focus on energy supply, energy distribution, energy storage and energy use. Through outstanding research results, successful industrial projects, company spin-offs and global collaborations, Fraunhofer ISE is shaping the sustainable transformation of the energy system.

In its business areas Photovoltaics, Energy Efficient Buildings, Solar Thermal Power Plants and Industrial Processes, Hydrogen Technologies and Electrical Energy Storage as well as Power Electronics, Grids and Intelligent Systems, the Institute develops materials, components, systems and processes. For this purpose, they have an excellent laboratory infrastructure at their disposal. In addition, Fraunhofer ISE carries out analyses, studies and consultations. They also offer their clients testing and certification procedures. Fraunhofer ISE is certified according to the quality management standard DIN EN ISO 9001:2015.

For more information: www.ise.fraunhofer.de