Specific heat and thermal conductivity of municipal solid waste and its effect on landfill fires

Abstract

Municipal Solid Waste (MSW) landfills are sources of physical, chemical and microbiological processes and as a result, gases and heat are generated as by-products. The generated heat flows from the higher to lower temperature regions within the landfill. Specific heat and thermal conductivities are two important properties that determine heat flow in MSW landfills. The goal of this study was to determine the thermal conductivity and specific heat capacity of MSW samples of Indian origin and to study its effect on landfill fires. Thermal conductivity and specific heat capacity of waste samples collected from dumpsite at Bhandewadi landfill, Nagpur & Bellahalli landfill, Bangalore (India) and the synthetic MSW (prepared in the lab) were determined using newly designed and fabricated experimental set-up. Results showed that moisture and organic content of MSW are directly proportional to specific heat capacity and indirectly proportional to thermal conductivity. Thermal conductivity of MSW is directly proportional to its density and specific heat is indirectly proportional to the density of MSW. MSW with specific heat and thermal conductivity in the range 0.003 J/g. K - 0.47 J/g. K and 0.35-3.6 J/s. m. K, respectively were found between 30 and 75 °C with 5% to 25% moisture content. As the temperature increases above 75 °C, decrease in thermal conductivity & increase in specific heat was observed and thermal conductivity of 0.07 J/s. m. K was observed at 130-140 °C. As a result of this, heat does not flow and gets concentrated in that region leading to landfill fire.

Keywords: Moisture content; Municipal solid waste; Organic content; Specific heat capacity; Thermal conductivity.