an official journal of: published by:
Editor in Chief: RAFFAELLO COSSU


  • Geo Jacob - Department of SciTec , Ernst-Abbe-Hochschule Jena , Germany - Department of Bioenergy Systems , DBFZ Deutsches Biomasseforschungszentrum gemeinnutzige GmbH , Germany
  • Frank Dienorowitz - Department of SciTec , Ernst-Abbe-Hochschule Jena , Germany
  • Nele Jaschke - Department of Bioenergy Systems , DBFZ Deutsches Biomasseforschungszentrum gemeinnutzige GmbH , Germany

DOI 10.31025/2611-4135/2022.15213

Released under CC BY-NC-ND

Copyright: © 2022 CISA Publisher

Editorial History

  • Received: 26 Feb 2022
  • Revised: 03 Jul 2022
  • Accepted: 03 Aug 2022
  • Available online: 14 Sep 2022


Composting experiments with heat recovery reveal spatial non-uniformity in parameters such as temperature, oxygen concentration and substrate degradation. In order to recover heat from static compost piles via integrated heat exchanger there is the need to investigate the temperature distribution for placing the heat exchangers and the interaction between heat recovery, substrate degradation and oxygen concentration to ensure quality of composting process. This study introduces a spatial model to predict the variation in controlling parameters such as temperature, oxygen concentration, substrate degradation and airflow patterns in static compost piles with heat recovery using Finite element method (FEM) in COMSOL Multiphysics ® Version 5.3. The developed two-dimensional axisymmetric numerical model considers the compaction effects and is validated to real case pilot-scale compost pile experiments with passive aeration. Strong matching with the real case experiment was achieved. The spatial model demonstrated that the compaction effect is extremely important for realistic modeling because it affects airflow, temperature distribution, oxygen consumption and substrate degradation in a compost pile. Heat recovery did not disrupt the composting process. Case studies revealed strong influence of convective heat loss through the edges and a 10 % improvement of heat recovery rate with ground insulation. The simulation indicates that an optimized placing of heat recovery pipes could increase the average heat extraction by 10-40 %.



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