A novel trigeneration system was designed in order to cover all space heating, DHW, cooling and part of the electricity demand of a multi-family building across Europe, based on the energy requirements derived from detailed building simulations, including user behaviour. A small-scale version of the system was then designed and its innovative subsystems (reversible heat pump/ORC, cascade chiller, low-emissions biomass boiler and solar collectors coupled with TEGs) were designed, developed and individually tested in lab conditions.
The developed reversible heat pump/ORC prototypes performed efficiently, especially under solar-assisted operation (COP > 4.5) while ORC operation proved to be efficient under high heat source temperature (> 90 °C) and low heat sink temperatures (< 25 °C). The cascade chiller configuration was made feasible through the indirect hydraulic coupling of the reversible heat pump/ORC to a modified adsorption chiller and COP values up to 5.5 could be achieved.
Referring to the biomass boiler, the implementation of exhaust gas recirculation, air-staging and a new control strategy leads to significant reduction of CO and NOx emissions by over 50 and 25%, respectively, and an efficiency of up to 105%. Using an internal heat exchanger for CHP operation, boiler efficiency exceeded 94%.
Measurements of the first TEG prototypes with the solar collectors showed that for an operation temperature of 120 °C, the TEG system could achieve an efficiency up to 1.7 %. In addition, innovative printed TEGs were developed and tested to investigate the possibility of improving the overall efficiency of the conversion process at a reduced cost.
A smart control strategy based on deep reinforcement learning was developed and its benefits were verified through simulations, especially during winter (reduction of operating cost by 35%) and intermediate season operation.
After individual testing, all the above subsystems were integrated into two prototype systems in Athens and Nuremberg. The systems were tested successfully under all operating modes (space heating, cooling, DHW and electricity supply) in both locations reaching TRL5. Also, simulations in real multi-family houses indicated that a high energy share of around 70% can be achieved, especially in heating-dominated locations.
Finally, a technology roadmap was developed, showcasing the next steps towards further developing this promising technology. This roadmap alongside two videos and communication material showing the project concept and the developed technologies can be found on the project website.
