This paper introduces a comprehensive mathematical model and computer program simulation of a miniature fire tube boiler using agricultural waste as primary fuel (biomass) for process heating application. The program can predict various operating parameters like composition of flue gas, pressure losses, temperature profiles in furnace and convective tube banks, heat transfer in radiant and convection section. The mathematical model is based on Plug flow modeling of furnace and discretization of convective tube bank, to improve the accuracy of the model. VBA Computer program is developed, which is verified and validated by using CFD and experimental results. This model is used for the optimization of boiler design.

Keywords: Biomass, Computational fluid dynamics, Discretization, Mathematical model.