Topic & aim

The project aims at the development of a system for utilization of the condensing heat of biomass-fired boilers. For maximum efficiency regardless of the operating temperature of the heating system, e.g. a district heating network, an absorption heat pump is applied, which serves for upgrading of the low-grade heat recovered from the wet boiler flue gas.

The development is targeted at medium (75 kW) to large size (some hundred kW) biomass boilers.
Due to the heat input to the evaporator of the heat pump, the flue gas of the biomass-fired boiler is cooled down to about 20 °C, resulting in an enhancement of the boiler efficiency of about 30%, depending on the water content of the biomass fuel. In total about 25% fuel savings compared to conventional biomass boilers with flue gas outlet temperature of 180 °C and 85 % boiler efficiency shall be achieved.
The driving heat for the heat pump cycle is provided by the biomass boiler. For that purpose the thermal design of the boiler is modified within the project.

Measures

University of Applied Scienes München

• Thermal concept, Layout of the heat pump cycle, Laboratory test: sorption heat pump

Scherdel Energietechnik GmbH

• Design and construction of the sorption heat pump

Focus

University of Applied Scienes München

• Development of conceptual details of the sorption cycle (e.g. thermosiphon design of the desorber, operating concept with minimal control activity

Scherdel Energietechnik GmbH

• Design of the sorption heat pump for low manufacturing cost and robust operation