5. Basic principle of biomass stove design
There are wide range of consumer needs and consideration to build improved biomass stove. It is difficult to find
single solution to accommodate different needs and considerations. Each particular stove commonly represents a
compromise to address the consumer needs, local resources, safety and ergonomic consideration.
The aims of developing improved biomass stoves are to increase fuel efficiency and reduce emission. Generally,
basic principle designs to achieve these aims are enhance heat transfer and combustion efficiency. Combustion
efficiency is the ratio of energy released during combustion to the total combustible energy potential of the fuel.
Perfect combustion prevents negative effect on emission. Incomplete combustion produce harmful emission such as
carbon monoxide (CO), unburned hydrocarbons (UHC), nitrogen oxides (NOx), smoke and soot [13].
Adequate draft and a proper air-to-fuel ratio are increasing combustion efficiency. Burner air opening will
influence fuel rate consumption, combustion temperature and efficiency. Stove size, geometry and placement of the
fuel inlet and combustion chamber must be able to accommodate burner air properly. Giving proper insulation
around combustion chamber increasing stove heat transfer [11].
The more energy absorbed by the cook pot relative to the amount of energy released by combustion chamber, the
higher heat transfer efficiency. Convective heat transfer is the primary method of energy transfer in an improved
biomass stove. Energy transfer through advection in the convection process has more effective mechanism and
proportional to the fluid velocity [22]. Improved biomass stove seek to maximize the velocity of combustion gases
as well as the pot surface area in contact with these gases [13].