Heat Transfer in Composting Systems

In order to control the composting process, microbially generated heat must be removed from a pile. This is to prevent the temperature of the substrate, which is a good thermal insulator, from reaching levels inhibitive to the resident microbial population. A model of the heat transfer mechanisms responsible for the removal of any excess heat has been constructed. The heat transfer mechanisms involved are convection and conduction, with radiation effects being assumed negligible.An energy balance has been constructed for the energy transfers into, within and out of a composting system. These three components of the energy balance equate to the change in energy stored within the system, which dictates the temperature within the composting substrate. Separate equations have been developed for each of these components, leading to a complete mathematical energy balance for a composting system. This balance is taken over an instant in time and is expressed as rate equations, in J/s.