Project meeting of STEP at the site of the company ATS - Agro Trading & Solutions in Hardegsen (Photo: DBFZ)

Heat Biomass furnace

Project ID 03KB133

BreBiSorp - Biomass-fired Boilers with Condensing Heat Utilization by Means of a Sorption Heat Pump

Logo BreBiSorp (Source: Munich University of Applied Sciences)


  • 01.10.2017 – 31.07.2022


University of Applied Science Munich
CENERGIE - Competence Center Energieeffiziente Gebäude und Quartiere, Department of Building Services Engineering
Lothstr. 34
80335 München

Prof. Dr. Christian Schweigler – Project leader
Telephone: +49-(0)89/1265-1575


03KB133C - Scherdel Energietechnik GmbH

Associated partners

Cooperation partners


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.


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


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


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