Mathematical Modelling and Performance Analysis of a Small-Scale Combined Heat and Power System Based on Biomass Waste Downdraft Gasification

Abstract

The paper presents a simple mathematical model for designing, optimizing and simulating small-medium CHP scale plant with use of biomass waste downdraft gasification. A downdraft gasifier has been used as the starting point in the study, due to its low tar content and effective way of using heat in the engine's exhaust gases to dry and pyrolyze the different solid biomass waste. Hot water from the cooling circuit of the engine and from producer gas cooling is directly used for the district heating network, air or steam preheating. The mathematical model includes modelled components as a downdraft gasifier, an internal combustion engine using the characteristic equation approach method. The mathematical model enables the outputs of the plant to be evaluated and calculated for different types of biomass and operating conditions. The results demonstrate that it is a useful tool for assessing the performance of CHP plants using several types of biomass waste and enables comparisons to be made between operating conditions for real applications.