Determination of thermal properties of compost bulking materials by using various methods

Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 13 compost bulking materials were determined in this study. Specific heat was measured by a differential scanning calorimeter. Transient heat dissipation and steady-state gradient methods were used for thermal conductivity and diffusivity measurements. Thermal properties were determined at varying compaction (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle size (ground and bulk), and water content (0, 20, 50, 80% of water holding capacity and saturated condition). The resulting thermal properties of compost bulking materials can be used to develop heat transport models for design of more optimal temperature control in composting systems.