Experimental Investigation and Performance Evaluation of Natural Draft Double-Pot Biomass Cookstove Using New Aircrete Insulation

Abstract

Biomass has been and still now is one of the most abundant renewable energy resources for cooking and heating applications in both household and industrial levels. However, ineffective and improper use of biomass fuels for cooking results in socio-economic and environmental problems. Those problems can be reduced by properly designing efficient and improved biomass cookstoves with enhanced performance. Thus, the major objective of this thesis is to design and experimentally investigate the performance of a locally constructed double-pot improved biomass cookstove using an Aircrete wall as new insulating material. Numerical simulation using ANSYS Fluent was carried out to compare the performance of cookstove models with different geometrical parameters. An experimental investigation is done to study the performance of the selected model with better performance and good agreement is obtained between the numerical and experimental results. For thermal conductivity test of insulating material, four samples of Aircrete walls with different ratio of, water, cement, foam, and light weight gravel was prepared. The test result showed that a sample with a ratio of 2.272% water, 58.25% cement, 17.54% foam, and 21.93% light weight gravel has a lower thermal conductivity of 0.1839 W/m.K and porosity 37.03% were selected as an insulating material for the development of the cookstove. Water boiling tests were conducted using 2.5kg of water and using eucalyptus wood log of moisture content of 10.03% as a feedstock. The result showed that for an average fire power input of 6.686 kW the overall efficiency, boiling time, and average specific fuel consumption were found to be 35.8 %, 15.166 min, and 140 g/l. The average deviation in the numerically predicted and experimental values of zonal temperature is 2.446 %. The result of exhaust gases emission showed that the average amount of CO and CO2 emission from the stove was found to 0.21% and 6.448 % volume, respectively. The use of Aircrete insulation results in a relative reduction of heat loss through the combustion chamber wall which is only found as 3% of total loss.

Biomass Has Been And Still Now Is One Of The Most Abundant Renewable Energy Resources For Cooking And Heating Applications In Both Household And Industrial Levels. However, Ineffective And Improper Use Of Biomass Fuels For Cooking Results In Socio-Economic And Environmental Problems. Those Problems Can Be Reduced By Properly Designing Efficient And Improved Biomass Cookstoves With Enhanced Performance. Thus, The Major Objective Of This Thesis Is To Design And Experimentally Investigate The Performance Of A Locally Constructed Double-Pot Improved Biomass Cookstove Using An Aircrete Wall As New Insulating Material. Numerical Simulation Using Ansys Fluent Was Carried Out To Compare The Performance Of Cookstove Models With Different Geometrical Parameters. An Experimental Investigation Is Done To Study The Performance Of The Selected Model With Better Performance And Good Agreement Is Obtained Between The Numerical And Experimental Results. For Thermal Conductivity Test Of Insulating Material, Four Samples Of Aircrete Walls With Different Ratio Of, Water, Cement, Foam, And Light Weight Gravel Was Prepared. The Test Result Showed That A Sample With A Ratio Of 2.272% Water, 58.25% Cement, 17.54% Foam, And 21.93% Light Weight Gravel Has A Lower Thermal Conductivity Of 0.1839 W/M.K And Porosity 37.03% Were Selected As An Insulating Material For The Development Of The Cookstove. Water Boiling Tests Were Conducted Using 2.5kg Of Water And Using Eucalyptus Wood Log Of Moisture Content Of 10.03% As A Feedstock. The Result Showed That For An Average Fire Power Input Of 6.686 Kw The Overall Efficiency, Boiling Time, And Average Specific Fuel Consumption Were Found To Be 35.8 %, 15.166Min, And 140 G/L. The Average Deviation In The Numerically Predicted And Experimental Values Of Zonal Temperature Is 2.446 %. The Result Of Exhaust Gases Emission Showed That The Average Amount Of Co And Co2 Emission From The Stove Was Found To 0.21% And 6.448 % Volume,Respectively. The Use Of Aircrete Insulation Results In A Relative Reduction Of Heat Loss Through The Combustion Chamber Wall Which Is Only Found As 3% Of Total Loss.