Development of numerical model for predicting heat generation and temperatures in MSW landfills

Abstract

A numerical modeling approach has been developed for predicting temperatures in municipal solid waste landfills. Model formulation and details of boundary conditions are described. Model performance was evaluated using field data from a landfill in Michigan, USA. The numerical approach was based on finite element analysis incorporating transient conductive heat transfer. Heat generation functions representing decomposition of wastes were empirically developed and incorporated to the formulation. Thermal properties of materials were determined using experimental testing, field observations, and data reported in literature. The boundary conditions consisted of seasonal temperature cycles at the ground surface and constant temperatures at the far-field boundary. Heat generation functions were developed sequentially using varying degrees of conceptual complexity in modeling. First a step-function was developed to represent initial (aerobic) and residual (anaerobic) conditions. Second, an exponential growth-decay function was established. Third, the function was scaled for temperature dependency. Finally, an energy-expended function was developed to simulate heat generation with waste age as a function of temperature. Results are presented and compared to field data for the temperature-dependent growth-decay functions. The formulations developed can be used for prediction of temperatures within various components of landfill systems (liner, waste mass, cover, and surrounding subgrade), determination of frost depths, and determination of heat gain due to decomposition of wastes.

Modelling the Potential Biogas Productivity Range from a MSW Landfill for Its Sustainable Exploitation

“…This may imply a shorter duration of the aerobic phase and, then, an anticipation of the acid phase and of the methanogenesis. Furthermore, considering the landfill divided into smaller and multiple sectors would imply a higher biogas generation, since the biogas production is influenced by the waste age [38] and smaller heaps are composed of waste that has been more recently dumped and covered. Indeed, the cultivation of the landfill sector by sector implies that the covering of each heap takes place after a shorter period with respect to the case of considering the landfill as an only heap.…”

Thermal Numerical Analysis of Vertical Heat Extraction Systems in Landfills

“…To account for the temperature dependence, the heat generation function with time was scaled with temperature (Liu 2007). Heat generation below 0°C and above 80°C was assumed to not occur, while peak heat generation was assumed to occur between 30°C and 50°C (Hanson et al 2013).…”

“…Yoshida and Rowe (2003) (Hanson et al 2013). Site specific data was used to simulate the materials (Table 2.5 and Table 2.6) and boundary conditions (Table 2.3).…”

Aerobic processes in landfill: an Australian field trial

“…Each of these techniques are discussed critically in the following sections. There has been a shift in recent literature to understanding the types of biological activity occurring in landfill through heat budgets, a short discussion of this method is also outlined (Hanson et al, 2013, Megalla et al, 2016.…”

“…In a similar fashion to mass balance approaches to landfills, the idea of heat budget through energy balances over waste parcels has been developed (Hanson et al, 2013, Megalla et al, 2016. Onedimensional heat transfer models heavily rely on empirical relationships to describe key parameters of specific heat capacity and thermal conductivity of waste (Megalla et al, 2016).…”