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.

1. IMPROVED CHULHA

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

12. TNAU CHULHA
Cost : 75/- Efficiency : 24%

13. TNAU DOUBLE POT CHIMNEYLESS CHULHA
• Double wall
• Tunnel
• Secondary air inlets
• Grate
• Legs (6)
• Inner wall holes
• Mounds
TNAU DOUBLE POT
CHIMNEYLESS CHULHA

14. TNAU DOUBLE POT IMPROVED CHULHA

15. TNAU DOUBLE POT CHIMNEYLESS CHULHA
Cost : 150/- Efficiency : 26%

16. DOUBLE POT
CHULHA
WITH
CHIMNEY

17. UDAIRAJ CHULHA
 Material
 Chimney
 Fire box
 Firebox opening
 Connecting tunnel
 Cost: 230/-
 Efficiency : 25.5%
Suggestions
• Soot removal hole
• Provide grate
• Optimize air opening

18. NOON MEAL
CHULHA
WITH
CHIMNEY

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

21. VESSEL
o Flat bottom or cylindrical shape
o Lids
o Clean and dried

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

25. CALCULATIONS
a. Total weight of food cooked (Wf)
b. Weight of char remaining (Dcc)

26. c. Equivalent dry wood consumed (fd)
d. Specific fuel consumption (SC)
e. Total cooking time (Dt)

27. APPLICATIONS
Girls’ Hostel

28. TNAU BIOMASS GAS STOVE
 Principle – updraft
gasification
 Woodchips, agricultural
residues, dry leaves, barks
 Cylindrical – clay and rise
husk
 Iron grate – 50mm

29. BIOMASS GAS STOVE WORKING CONDITION

30. PREFORMANCE DETAILS OF BIOMASS GAS STOVE
Working Principle : Updraft Gasification
Feedstock : Wood chips, agricultural
residues, such as coconut shell, groundnut
shell, arecanut husk etc.
Thermal  : 24-28 %
Flame temp : 600-700 0C
Heat output : 4.4 kW
Heat release rate : 63 kcal/min
Emissions -
CO : 500 ppm
TSP : 0.10 mg/m3
Sp. fuel consumption : 0.27 kg/h
of processed food
Saving in fuel : 15-18 % over
conventional stove
Cost : Rs. 300
Applications : Small scale thermal applications in farms, households,
Tea shops, Turmeric boiling, Paddy Parboiling, etc.

31. BIOMASS GAS STOVE – CHARACTERISTICS

32. BIOMASS GAS STOVE AT USER’S SITE AT OOTY

33. COMPARATIVE PERFORMANCE OF WOOD BURNING
STOVES
Details Conven-
tional
Single Pot
Chulha
Double Pot
Chulha
Biomass Gas Stove
Working principle Combustion Combustion Combustion Gasification
Thermal , % 10-12 19-24 24-26 24-28
Flame temp, 0C 400-500 400-500 400-500 600-700
Heat output, kW 0.7 1.2 1.8 4.4
Heat rate, kcal/min 10 16 22 63
Emission CO-ppm
level TSP- mg/m3
3500
0.69
2000
0.20
1500
0.20
500
0.10
Cost - Rupees 55 75 150 300
Sp. fuel consumptn 0.36 0.30 0.30 0.27
Saving in fuel, % -- 9-11 10-13 15-18
Application Household
heating
Household
heating
Household
heating
Houses, Farms, Tea
shops, Turmeric
boiling, Paddy
Parboiling

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

35. TESTING OF BRIQUETTES IN BIOMASS GAS
STOVE
ASH CLINKERS