Modifications in traditional Indian cookstove and improved cookstove for efficient design Amit...
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Modifications in traditional Indian cookstove and improved cookstove for efficient design Amit Ranjan Verma*, Rajendra Prasad, Risha Mal, Ratnesh Tiwari,V
Modifications in traditional Indian cookstove and improved
cookstove for efficient design Amit Ranjan Verma*, Rajendra Prasad,
Risha Mal, Ratnesh Tiwari,V. K.Vijay Research Scholar Biomass
cookstove Division Centre for Rural Development and Technology
Indian Institute of Technology New Delhi India
Slide 2
Energy Access- Present Status & Projections Present Global
Scenario 1.3 billion people have no access to electricity and 2.7
billion people rely on biomass and traditional fuels for cooking;
More than 95% of these peoples are either in Sub Saharan Africa or
in Developing Asia and 84% are in rural areas. Developing Asia Over
1.9 billion people in developing Asia still rely on traditional use
of biomass for cooking; More than 100 million each in Bangladesh,
Indonesia, Pakistan and Myanmar without access to clean cooking
facilities. Contd 2
Slide 3
Indian Households Energy Scenario (Census 2011 ) Over 85% of
households in rural areas depend on traditional fuels for cooking,
with only 9% using LPG, Kerosene, biogas or electricity. In urban
India on the other hand, 76% of households use LPG as the major
fuel for cooking and only 18% use traditional biomass fuels for
cooking. Between 2001-02 and 2009-10, the percentage of households
in rural areas using traditional fuels remained at 85%. Nearly
500,000 premature deaths every year specially among women and
children due to exposure to smoke and fumes from burning of
biomass. 3 Rural Households in million (%) Urban Households in
million (%)
Slide 4
Improved Biomass Cookstove Cook-stoves with chimneys and closed
combustion chambers are usually considered improved. Advantages of
Improved Biomass Cookstoves Improved Biomass cookstoves can have
efficiency ranging from 25-50%, give out very low level of
emissions. It saves fuel and time of cooking Emits less CO and
others Pollutants. Less harmful effects on human health.
Classification of Biomass Cookstoves Open fire and shielded fire
Portable and fixed cookstoves Single pot and multiple pot
cookstoves Combustion and Gasifier cookstoves
Slide 5
The setup at IIT Delhi
Slide 6
The following tests are regularly conducted in the laboratory
as per the Indian BIS for performance evaluation of the Biomass
Cookstoves. Measurement of the Calorific value of the fuel.
Measurement of the Moisture Content of the fuel. Measurement of
Burning Capacity (Rate) of the stoves Thermal efficiency of a
Cookstove using Water Boiling Tests Stove Emissions
Slide 7
Parameters or Factors affecting the Performance of cookstove
Fuel type and size The size of wood considerably affects
combustion. Large or thick piece of wood are difficult to burn and
emit more smoke. Small pieces tend to give higher flames and burn
for a shorter time than the same mass of bigger pieces. For this
study Fuel type and size were fixed according to the BIS standards.
Eucalyptus wood cut from the same log into size of 3 cm 3 cm square
cross-section and length of half the diameter of combustion
chamber. Moisture content of fuel All biomass contains some water
which must be evaporated before the biomass can burn. Moisture
content fixed of 5 (1) % on wet bases to avoid variation in
calorific value
Slide 8
Burning rate Burning rate define how much amount of fuel can be
burn in given time period, in given cookstove. All stove have
optimal burning rate on either side of which efficiency decreases.
This optimal is not fixed, but depends on various factors such as
size of grate, distance between grate and pot bottom, presence or
absence or secondary air provision.
Slide 9
Support height or Gap It is height or gap between top plate of
cookstove and pot bottom. Stove with small support height although
have high efficiency, but they also reduce the amount of gas that
can flow through the gap and thus limit the firepower. In case of
larger fire either smoke will pour out the stove door, or else the
fire will be choked and suffer poor combustion or simply not build
up to desire power. Important to optimize the support height for
each design of stove.
Slide 10
Primary, Secondary and Excess air Primary air is air provided
at the bottom of the grate and from door of biomass cookstove. It
helps in the burning of wood or charcoal on grate. A substantial
proportion of volatiles escape unburnt or partially burnt along
with the combustion product, resulting in a loss of the heating
value of wood. Appropriate injection of secondary air in column of
unburnt volatiles is expected to retrieve some of the heat.
Although the role of primary and secondary air has been recognized,
but incorporation of feature in design is not so simple. The
optimum amount of each, the point of injection of secondary air,
the effect of their temperature etc. are not yet very well
understood.
Slide 11
The amount of secondary air to be provided depends on the
fraction of the oxygen in primary air left unused and combustion
gases left unburnt. The theoretical amount of air required for
stoichiometric combustion of wood can be calculated from its
elemental analysis. To calculate the actual amount of air required,
the theoretical amount is multiplied by excess air factor which is
generally between 1.5 to 2.5. The amount of air required for
stoichiometric combustion in excess of theoretical minimum is known
as excess air. Excess air is required to ensure proper burning of
wood and volatiles. The amount of excess air required depends on
the degree of mixing or turbulence available in combustion
chamber.
Slide 12
Grate The use of grate in a stove is expected to facilitate the
accessibility of air to a fuelbed. It promotes the combustion of
charcoal that remains after the volatiles are driven out of wood.
In general grate will generate higher power outputs from a given
fuelbed area.
Slide 13
Modifications in traditional Indian cookstove
Slide 14
Traditional Indian cookstove Traditional Indian cookstove
simulated in lab Traditional biomass cookstove in India are
generally U shaped with three side closed and front open.
Slide 15
Modification made in traditional Indian biomass cookstove
Traditional Indian cookstove with grate S.No. Efficiency CO(g/MJ)
PM(mg/MJ) 123.5010.67553.28 Performance Evaluation of Traditional
Indian cook stove
Slide 16
Traditional Indian cook stove with grate Experiments have been
carried out and it has been found that traditional biomass
cookstove with grate has 10% more thermal efficiency as compared to
traditional biomass cookstove without grate. There is some
reductions in the particulate matter generated but there did not
appear any reduction in the CO emissions per unit of energy
delivered to the cooking pot. S.No. Efficiency CO(g/MJ) PM(mg/MJ)
127.06510.38447.005
Slide 17
Modifications in improved cookstove for Efficient design
Slide 18
Efficiency and emission performance of Improved biomass
cookstove was tested in according to Indian BIS (As per Draft
Revision Standard 2012), and the following results were obtained:
Natural draft cookstove Thermal Efficiency was lower than BIS
LIMITS. Hence it has been decided to modify existing design so that
it could meet the Indian BIS requirement. Approaches to make
modification in existing design Theoretical design procedure
Results of parametric study S.No.Power output(KW)Thermal
EfficiencyPM(Mg/Mjd)CO(g/Mjd) 11.4222.86167.023.48
21.2622.38178.324.51 Average1.3422.49172.673.995
Slide 19
Theoretical design procedure In this approach it has been
decided to check the dimension of biomass cookstove according to
theoretical design procedure given by K.K. Prasad (A woodstove
compendium 1981). Conclusion from theoretical design S.noParameters
Theoretical dimension(cm) Actual dimension(cm) 1 Inner Diameter for
combustion chamber 21.6118 2Vertical distance between grate and pan
bottom(h) 10.5220
Slide 20
Parametric study Theoretical dimensions of cookstove was not
meeting with the actual dimensions. So it has been decided to
follow parametric study results to make modification in existing
model and hence different set of experiments have been concluded to
modify existing design parameter like : Grate porosity Height of
grate from base Decrease in the height between top plate and lid
and Varying burning rate without changing the back bone of existing
cook stove.
Slide 21
S.No.Support Height(cm)Other Modification Power(K W) Efficiency
CO(g/ Mjd) P.M.(M g/Mjd) 15none1.123.85.5218 25none1.123.65.7247
3Decreased to 0.5Fuel loading door half1.123.512385 4Decreased to
0.5none1.429.99.1509 5Decreased to 0.5Grate increased to
5.51.429.710235 6Decreased to 0.5Grate increased to
5.51.428.59.6245 7Decreased to 0.5Grate increased to
5.51.224.38.9419 8Decreased to 0.5Grate increased to
5.51.332.58.4378 9Decreased to 0.5Grate increased to 5.51.334.38251
10Decreased to 0.5Grate increased to 5.51.132.47.9345 11Decreased
to 0.5Grate at 31.231.97.7381 12Decreased to 0.5Grate increased to
71.332.515771 13Decreased to 0.5Grate increased to 70.828.57.6465
14Decreased to 0.5Grate increased to 5.51.235.48.1395 15Decreased
to 1Grate increased to 5.50.925.69.7364
Slide 22
16Decreased to 0.5New Grate with large porosity0.824.39.4404
17Decreased to 0.5New Grate with large porosity1.127.59.8415
18Decreased to 0.5 1 st Grate with large porosity raised to 5.5 cm,
2 nd original grate at 3 1.1289.6380 19Decreased to 0.5Grate
increased to 71.435.86.6389 20Decreased to 0.5Grate increased to
71.632.514878 21Decreased to 0.5Grate increased to 71.235.85.4377
22Decreased to 0.5Grate increased to 71.236.65.9423 23Decreased to
0.5Grate increased to 71.234.16.2413 24Decreased to 0.5 Grate
increased to 7, sec air holes present in base closed 128.68.2741
25Decreased to 0.5New Grate height 7 less in diameter128.312459
26Decreased to 0.5 Grate of vikram 6 used at increased height of
5.5 1.131.37.2522 27Decreased to 0.5none1.831.512635 28Decreased to
0.5Grate of vik6 h= 3cm130.56.4409 29Decreased to 0.5Grate of vik6
h=7cm1.131.57.6515 30Decreased to 0.5Grate h = 81.133.66.7404
31Decreased to 0.5Grate of vik 6 = 8cm1.1338.8515 32Decreased to
0.5Grate h = 7cm, fuel loading door half1.131.77.6591
Slide 23
33Decreased to 0.5 Grate height 7cm increased base height from
ground 3 inches 1.233.85.6435 34Decreased to 0.5Grate h = 3 with
aluminum sheet1.1316.6626 35Decreased to 0.5New grate with high
porosity h=7129.67.1407 36Decreased to 0.5 1 st grate with large
porosity raised to 8 cm, 2 nd original grate at 5 cm 1.1328.7405
37Decreased to 0.8Original grate 8 cm1.131.57.6370 38Decreased to
0.8Original grate 8 cm1.431.87.6751 39Decreased to 0.8Original
grate 8 cm1.425.86.8884 40Decreased to 0.8Original grate 8
cm1.632.66.2735 41Decreased to 0.8Original grate 8 cm1.530.25.1458
42Decreased to 0.8Original grate 3 cm1.429.93.8440 43Decreased to
0.8Original grate 3 cm1.428.13.4438 44Decreased to 1.2vik 6 grate 3
cm,1.327.34.3414 45Decreased to 1.2vik 6 grate 3 cm,1.428.74.7421
46Decreased to 1.2vik 6 grate 4 cm,1.327.56.8463 47Decreased to
1.2Vik 7 grate 5cm1.3427.925.21353.43 48Decreased to 1.2Vik 7 grate
5cm1.3127.256.31400.73 49Decreased to 1.2Vik 7 grate
5cm1.2325.495.01358.66 50Decreased to 1.2Vik 7 grate
5cm1.3628.223.74364.47
Slide 24
Conclusion from parametric study Parametric study concluded
that combination of different parameter with given modification can
meet the Indian BIS standards. Modification made in Existing Design
1)Modification in Grate height: Distance between base plate and
grate is increased from 4 to 5 cm. 2)Modification made in Support
height: Distance between top plate of cookstove and pot is
decreased from 5 to 1.2 cm.
Slide 25
Natural draft biomass cookstove Without any Modification
Natural draft biomass cookstove With Modification
Slide 26
S.No. Power Output(KW) Thermal Efficiency PM(mg/MJd)CO(g/mJd)
11.3427.92353.435.21 21.2325.49358.665.01 31.3628.22364.473.74
Average1.3127.22358.854.65
Slide 27
Conclusion Experimentally it has been concluded that
modifications can be done in existing cook stoves for enhanced
efficiency and low emissions by varying parameters such as Grate
porosity, Height of grate from base, Height between top plate and
lid and Burning rate without making major changes in the structure
of existing cookstove such as diameter and secondary air inlet
points.
Slide 28
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Slide 29
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