Improved chulhas are scientifically designed, environmental friendly cookstoves with a thermal efficiency of about 20 per cent or more as compared to 5% to 10% efficiency of traditional chulhas.
2. INTRODUCTION
Wood is an important energy source in rural India
Wood energy is declining in the increasing rate
because of rapid depletion of natural forest resources
Main uses of wood energy is for cooking
3. TRADITIONAL WOOD STOVES
Three stones fire
Why Popularly adopted?
• Feeding and combustion control easy
• Any size pot can used
• No special skill required
• Control of insects
Drawbacks
• Low efficiency (8-10%)
• Smoke formation
• Use of fuel wood inefficiently
4. NEED FOR IMPROVED WOOD STOVES
To prevent smoke and soot production
For saving fuel wood
Women labour time
To reduce lung and eye diseases
5. IMPROVED STOVES
Less smoke production
Less quantity of fuel utilization
Efficient heat transfer
Less heat losses
Efficiency (20-35%)
6. STOVE COMPONENTS
FIRE BOX
• Enclosed space for combustion
• High energy release due to complete
combustion
AIR INLET
• Secondary air is introduced in the fire box
GRATE
• Made up of frame of metal bars
• Increased efficiency due to entry of
secondary air if grate and air inlet is used
7. BAFFLES
• Projection in the combustion chamber
placed at the exit of combustion chamber
DAMPERS
• Movable plate in the chimney
• Made up of steel plate
CHIMNEY
• Metal or asbestos pipe
• Helps in releasing the smoke and creates
draft for complete combustion
8. COWL
• Metal cap for avoiding the
entry of foreign material as
well as rain water
• Increases the draft
TUNNEL
• In multi-pot closed chulha
9. DESIGN PRINCIPLES FOR EFFICIENT
STOVES
Insulate the combustion chamber
Use an upright chimney with damper
Heat energy should be used only for the burning of
fuel
Maintain a good air velocity through the fuel for
complete combustion
Minimum quantity of excess of air during combustion
Distribute airflow around the fuel surfaces
Air should largely flow through the glowing
coal/wood
10. SINGLE POT TNAU CHULHA
Double wall
Grate
Legs
Secondary air openings
Inner wall holes
Mounds
Fire mouth
TNAU SINGLE POT CHULHA
11. SINGLE POT TNAU CHULHA
Double wall
Grate
Legs
Secondary air
openings
Inner wall holes
Mounds
Fire mouth
TNAU SINGLE POT CHULHA
19. CPRI DESIGN CHULHA
Non-chimney
Availability in sizes
Portable
Cost: 175/-
Efficiency : 26%
SUGGESTIONS
• Adjustable air opening
• Provide tray like structure
• Side insulation
20. EVALUATION OF THERMAL EFFICIENCY
WATER BOILING TEST
o For determining thermal efficiency of wood stove
o Location specific multi-model approach of
government for popularization of locally made stoves
o Uniform testing code for performance evaluation
INSTALLATION OF CHULHA
o Site
o Chimney
o Fuel opening
22. CALCULATIONS
H1 = w1i(t2-t1) + w2i(t3-t1)
H2 = (w1i - w1f)L + (w2i - w2f)L
H1+H2
η = -----------
mF x CV
mF x CV x η
Power Rating = -----------------------
860
PROCEDURE
23. CONTROL COOKING TEST
• To assess the performance of the improved stove
• Standard cooking task
FUEL
o A homogeneous mix
o Divided into pre-weighed bundles
24. FOOD AND WATER
o Sufficient
o Homogenous
COOKING POT (S)
o Most appropriate pots
o Record the specifications
34. CONCLUSION
We can use the improved wood stove designs to
reduce the concentration of smoke and indoor air
pollution
We can save the time and money