Estimation of bulk parameters of a composting process in windrows

A program based on a lumped parameter model was developed to estimate three parameters of a composting process in windrows. The first two parameters r epresent two types of heat loss from the compost pile. The third parameter represents the effective composting rate. Most of the heat is dissipated at a rate proportional to the total biodegradable mass in the pile. Heat loss due to natural ventilation through the pile is much smaller and is associa ted with extremely low air velocities. Two alternative rate functions were investigated: a temperature-dependent function and a constant derived direc tly from measurements of the biodegradable mass. The empirical constant pro vided a better estimation. The values of the estimated parameters can be us ed to compare different composting processes and to evaluate potential impr ovements. The variation in mass and temperature of the pile during the comp osting process can be forecasted based on measured data from the initial tr ansient phase. (C) 1999 Silsoe Research Institute.