CFD Simulation Analysis, Scale up and Field Testing of 200 Liters Biomass Fired Institutional Cook Stove.

Abstract

In this work, complete analysis of 200 liter institutional cook stove, design, simulation and field test was carried out. In developing country including Ethiopia biomass is the major energy source especially, for cooking and heating purpose from single family to institutional level. The students’ cafeteria kitchen of Jimma University, Ethiopia are using biomass fired traditional three stone and enclosed chimney stoves. To solve the smoky operation problem Jimma University carried out a pilot study with InStove make institutional stove (four with 100 liter size and two 60 liter size). To implement more of these stoves what problem is that students’ cafeteria kitchen are using 200 liter size for cooking and boiling tea since large number of students are getting serviced. In this back drop, this project will focus on 200 liter size of institutional cook stove that incorporates secondary air for complete combustion and ease ash removal. Materials were selected for each component of the stove according to their temperature resistance required. Dimensions were derived for each of the components by equating the ratio of volume increment from existing 60 liter to 100 liter, and from 100 liter to 200 liter through scale up. The stove performance test was done using water boiling test protocol for the new stove and parametric calculations were done using WBT (Water Boiling Test) version 4.2.2. Comparative assessment of the result obtained for the stove with and without inner refractory insulation has been done. The inner combustion chamber insulation used was construction sand that is not the right material for insulation purpose. From the result, the one without inner insulation were selected since it recorded a high thermal efficiency of 53.4%. Validation of CFD (Computational fluid dynamics) simulation was done by comparing with experiment results. Different cases were investigated for different percent of primary and secondary air combination for specific air fuel ratio. The simulation was based on wood-volatileair as the fuel. Based on simulation result 60:40 primary vs secondary air supply was found to be best option compared to 75 : 25 and 50 : 50. The stove require a SFC of 41.25 gram per liter and average cooking time of 129.5 minute for 200 liters. Further work is recommended, which explore the possibility of making cast for inner chamber as well as preparing the InStove for other function, like, i.e. cake and enjera baking and working on optimization of the same model.