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

Heat Biomass furnace

Project ID 03KB026

SmallFurOpt - Optimization of small scale biomass heating systems by improvement of the hydraulic and control engineering concept and development of a new sorptive heat extraction to increase efficiency and reduce emissions

Fire in the pellet boilder (Photo: R. Kunde, ZAE)


  • 01.09.2009 – 30.11.2012


Bavarian Center for Applied Energy Research Garchingen (ZAE)
Walther-Meißner-Strasse 6
85748 Garching

Dipl.-Ing. Robert Kunde – project manager
Telephone: +49 (0) 89 329442-26
E-mail: robert.kunde‍@‍


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Results are only available in German.


In order to evaluate the efficiency of a central heating system the entire system (heat source, hydraulic and control engineering, heat consumer) has to be taken into account. Our previous investigations show a high optimization potential on many existing wood pellet heating systems.


The main targets are systematic laboratory tests to estimate the influence of hydraulic and control engineering on emissions and annual efficiency of wood pellet boilers. Therefore different boilers are operated under typical conditions with realistic load profiles. Furthermore a new concept of sorptive heat extraction of the flue gas is carried out by laboratory tests. An open sorption process has a higher efficiency than the conventional flue gas condensation which requires low return temperatures.


The test rig includes measurement devices for gaseous (e.g. CO) and particulate matter (PM) emissions, energy input (fuel mass and auxiliary energy) and energy output (useful heat) and hydraulics (buffer storage, controllable heat sink for simulating the heating circuit and domestic hot water consumption). Practical optimization tools and solutions are determined.
The second work package includes the proof of concept for an innovative heat extraction by a hygroscopic “heat transfer fluid” (LiCl brine) and the analysis of alternative hygroscopic media. The efficiency of absorption based flue gas condensation will be examined with bench scale testing.


  • Entire wood pellet central heating systems
  • (Annual) efficiency
  • Emissions
  • Hydraulic and control engineering
  • Optimization sorption
  • Sorptive heat extraction


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