SEEDS
designing and implementing an innovative multi-source heat pump system
that uniquely utilizes ammonia (R717) as a natural refrigerant
Project Scope
The SEEDS project aims to reduce the thermal energy demand of buildings and enable energy flexibility to increase renewable energy (RES) integration, ultimately enhancing grid stability in a cost-effective manner with a low life cycle environmental impact. In this project, Psyctotherm is responsible for designing and implementing an innovative multi-source heat pump system that uniquely utilizes ammonia (R717) as a natural refrigerant, rather than conventional synthetic refrigerants. This ammonia-based system leverages solar, geothermal, and ambient sources to provide efficient heating and cooling. Equipped with an advanced control strategy, the system dynamically selects the optimal heat source or uses a hybrid mode to maximize the coefficient of performance (COP), ensuring both high efficiency and environmental sustainability.
Key project Details
The cogeneration system that will be developed In the frame of the research project will have a thermal and an electrical power of 200 kW and 20 kW respectively. The properly controlled combustion of biomass will take place at 130oC, while the condensing temperature of the ORC cycle will be about 50 οC, given as thermal power to the greenhouse. The studied system will cover the thermal needs of a greenhouse of 300 m2.Organic fluid selection: An important research element has been the selection of the appropriate working fluid. According to the European Refrigerant Regulation, also known as the F-gas Regulation, the use of organic fluids with high Global Warming Potential (GWP) has begun to be limited in order to reinforce the use of environmentally friendly fluids. In addition, all fluids should have zero Ozone Depletion Potential (ODP). In this context, and in order to ensure the future use of the Greenco unit without any restriction, the R1224yd (Z) has been chosen, which is one of the most efficient for heat transfer in the range below 120 oC and also has a low GWP.
In the context of GreenCo project, Psyctotherm successfully developed an ORC engine integrated with a 200 kW thermal biomass boiler, utilizing a combustion temperature of 130 °C. The ORC system generated up to 20 kWe, while its cooling system, operating at 50 °C, supplied heat to a greenhouse to meet its heating needs. Using HFO refrigerant, chosen for its ultra-low global warming potential (GWP) and suitability for this temperature range, the cogeneration system was installed and operated at the Agricultural University of Athens. The project demonstrated the substantial benefits of combining ORC technology with biomass boilers in agricultural applications, highlighting a practical solution for sustainable energy use and enhanced efficiency in rural energy systems.
Co-Funded by the European Union
