Heat pumps for high-efficiency waste heat recovery for district heating system

Heat pumps have been installed to recover low-temperature cogeneration waste heat, increasing capacity, improving efficiency and reducing CO₂ emissions for a district heating system in Italy. The heat pumps selected can be specified with R-1234ze(E), R-513a or R-134a, although according to the heat pump model stated, R-1234ze(E) appears to be the specified refrigerant from the manufacturer’s literature.

The plant includes three cogeneration sections, each with electrical power of 1,334 kW. To improve system efficiency, one heat pump was installed on each cogeneration engine, enabling low-temperature waste heat to be recovered and upgraded to a usable temperature for district heating distribution. The installed heat pump units recover low-grade energy at approximately 30°C and raise it to around 80°C, the minimum usable temperature required for district heating distribution [according to the heat pump specifications for the 3 refrigerant options only R-1234ze(E) can achieve the 80°C requirement].  Because the units are paired with the cogeneration plant, they can also be powered by electricity generated on site. Now fully commissioned and operational, the project is expected to deliver a return on investment in less than two years.

According to the project participants, district heating operators are looking for scalable ways to improve performance and make better use of the energy already available within their systems, with the project showing how heat pump technology can unlock additional value from existing cogeneration infrastructure, supporting both decarbonisation goals and long-term asset value.

Sources: manufacturer’s information reported in Heat Pump News and Cooling Post