Simulation of heat transfer in a landfill with layered new and old municipal solid waste.

Due to rapid degradation of the newly filled municipal solid waste (MSW), the local temperature of the waste layer increases greatly. The mechanical parameters related to waste degradation and the deformation of high-density polyethylene (HDPE) pipes in the waste body will be affected by the elevated temperature. To predict the temperature distribution in the anaerobic landfill, a one-dimensional heat transfer model is established in this study. This model considers the stratification of the saturated and unsaturated zones, and the layering of new and old waste. Furthermore, a single peak model for heat production is applied as the source term of heat production. The stratification of the unsaturated and saturated zones is considered by distinguishing the difference in heat conductivity and specific heat capacity. The layering of the new and old waste layers is considered by distinguishing the difference in the length of time that waste has been degraded to produce heat. Based on the numerical calculation method, the temperature distribution in a landfill with layered new and old MSW is well simulated. The position where the maximum temperature occurs and the variation in the temperature at the edge of new and old waste are elucidated. The sensitivity analysis shows that the influence of the density on the temperature distribution is more significant. Besides, the stratification of saturated-unsaturated waste should also be considered in landfills.