Design Description, Analysis and Calculation of Micro Hot Point Improved Biomass Stove of Sai Grameen Udyog Faridabad, Hayana

Design Description, Analysis and Calculation of Micro Hot Point Improved Biomass Stove

of

Sai Grameen Udyog

Faridabad, Haryana

By

Bibhu Prasad Mohanty

Good Will Promoter Of  Micro Hot Point Improved Biomass Stove 

bibhu65@gmail.com

Design Description

The Micro Hot Point Improved Biomass Stove generally consists of a combustion chamber, a top section and a base. The hearth of the combustion chamber is made of perforated stainless steel plate , the outside of which encased in a mild steel casing. The grate or fuel bed is at the base of the combustion chamber. The base of the stove consists of a door for loading fuel wood into the combustion chamber, and few whole in the base which serve as combustion air inlets to the chamber. A drawer is incorporated at the base to facilitate the removal of ash which would have collected at the tray. The top of the stove consists of the pot seat, designed to accomodate any type heating utensils. The pot seat is designed such that the pot sinks to a depth below the top- most level of the stove. The stainless sttel ring selected for use is such that has the internal diameter equal to or closest to the external diameter of the cooking pot, thus ensuring that there is little or no clearance for pass above the pot seat. The diameter of the combustion chamber is such that it is smaller than the pot seat or the external diameter of the smallest pot that can be utilized on the stove. This is to ensure that the maximum amount of heat is transferred to the base of the pot . The distance between the fuel bed and the pot seat is also selected to allow for enough time for the complete combustion of the burning fuel particles before it strikes the base of the pot mounted on the pot seat.

Combustion Air Requirement

Following Ramakrishna (1992), a typical fuel wood has the following ultimate analysis by mass as shown in Table 1.

Table 1. Mass analysis of a typical fuel wood.

C	H2	O2	N2	H2O	Ash
40.4%	4.2%	33.9%	0.3%	20%	0.2%

The combustion analysis based on the above mass composition gives a stoichiometric Air/Fuel ratio, A/F= 4.6107 kg air/kg fuel. For an actual air supply which is 20% in excess of stoichiometry, actual air/fuel ratio, A/Factual= 5.53284 kg air/kg fuel.

Key Features of Micro Hot Point Improved Biomass Stove : Single burner Height 12 inches Stainless Steel Combustion Chamber Bakelite handles Durable steel construction No moving parts Light weight (4kg) Removes need to blow on fire

Performance Parameters:

1. Thermal Efficiency 25.4%
2. CO/CO2 Ratio 0.02
3. Output Thermal Wattage 1.2kW
4. Burning Capacity 0.8-1.1 kg/hr.
5. Average Product Lifespan: 5 years.

Discussion of Results of different tests

The results as per the test protocols of IIT, New Delhi show that the biomass stove has a maximum thermal efficiency of 25.4% and power delivery of 1.4kW, but a minimum specific fuel consumption of 0.492. This indicates a better performance when compared to the average thermal efficiency value of 17.9% for traditional mud stove as reported by George (1997), or the Kilakala stove which has a fuel saving capacity of 30% (Crewe 1990, Otiti 1991). The performance is also better when compared to the Improved Vented Mud stove (IVM) which has the average thermal efficiency values across fuels that varies from 10% to 23% which is comparable with the range of 10.8% to 19.6% reported by Pal and Joshi (1989). Furthermore, the thermal efficiency of the wood stove is not higher when compared to the thermal efficiencies of petroleum based fuel stoves such as the LPG stove, the kerosene wick stove, and the kerosene pressure stove with thermal efficiencies of 53.6%, 50% and 47%, respectively (TERI 1987).

Enahnced Performance:-The enhanced performance can be attributed to a number of factors. The first is the insulation provided round the combustion chamber. This minimizes the rate of heat loss across the wall of the combustion chamber by conduction and radiation,and ensures that a good proportion of heat is conserved within the chamber and directed towards the top of the chamber. The second is the smoke rings provided which eliminate the horizontal clearance between the pot and the pothole. This minimizes heat loss by radiation through the annulus between the pot and the pothole. The third factor is the design of the pot seat and the position of the flue gas exit port This ensures that the base of the pot sinks to a depth inside the pothole such that there is no vertical clearance between the pot base and the top of the stove, and that there is longer interaction between the flame and the pot base, bringing about maximum heat transfer to the pot, before the flue gases exit into the chimney. There is also the factor of availability of sufficient air that ensures the complete combustion of the fuel wood. On smokiness, it was observed that virtually all the flue gases was conveyed out of the test area through the chimney. The very small quantity of smoke noticed might have escaped as a result of construction inaccuracy in the roundness of the smoke rings leaving a very small gap between the pot and the ring. The escaping smoke, however, quickly diffuses into the air, causing insignificant fouling and irritation effects. It would be seen that the modifications made in providing insulation around the combustion chamber and sizable air inlet from base to admit adequate quantity of air for combustion, incorporating smoke rings to seal the annulus between the stainless steel pot and the pothole, and redesigning the configuration of the pot seat and the position of the flue gas exit port, have served to increase the thermal efficiency and therefore the percentage heat utilization of the stove. There has also been a drastic reduction in the smokiness of the stove, making it to be more user-friendly in health, comfort and convenience. Further modifications focused at redesigning the pot seat vis-à-vis the flue gas exit port in such a way that will minimize heat loss by radiation and convection, and ensure maximum heat transfer to the base of the pot can be pursued in future

How to operate it:- Fill the fuel wood entrance with dry wood. Then fill the inner cavity of the chula from the top with dry small twigs, dry leaves and fire those from top. There is no need of ferosene at all. Within 2 minutes chula will be ready for cooking. It has very less smoke, saving of at least 65% fuel. That takes care of household indoor atmosphere. Small kitchens of rural houses remain free from fumes and congesting carbon monoxide, carbon dioxide and other harmful smokes. Fuel wood smoke from kitchen in rural households is a major reason of bad health of women and children both. It is observed that the smoke of fuel wood is equivalent to 70-150 cigarettes per day.

Advantages of Micro Hotpoint Improved Biomass Smart cook stove as compared to traditional mud stove/ three stone fires:

Less Fuel:

1. 70% less consumption of fuel
2. Reduces drudgery of women collecting fuel wood
3. Reduced deforestation due to less consumption of fuel wood
4. Reduces dependency on plant fuel wood

Less Smoke:

1. 65% reduction in smoke (particulate matter)
2. Beneficial in terms of reduced Indoor Air Pollution (IAP) and healthier environment for women and children
3. Reduces global warming due to reduction of black carbon and other warming agents
4. Very less blackening of cooking pots and kitchen walls due to negligible cabon shooting

Less Cooking Time:

1. Reduces the cooking time by approximately half
2. Less exposure of women to kitchen smoke so people around cooking place do not feel fatigue due to smoke
3. More time for economic/ recreational activities

Local Fuel:

1. Locally available solid biomass used as fuel. Mostly dry twigs, dry leaves, dry cowdung cake, dry other animal dungs, crop wastes, tree wastes, after use wastes from biomasses.
2. The fuel required does not demand the establishment of separate fuel supply chains and facilitates local biomasses insignficant for fuel purpose
3. Timely and easy availability of cooking fuel around the household area. Thus it improves the autonomy of woman over kitchen.

Environmental benefits

This Smart stove meets the several Indian standards for efficiency and emissions. Testing and user feedback suggest that the Smart stove wood and neglected fuel biomas uses from an average of 1.1 kg per hour , thus saving 2.1 tonnes/year per household. There is huge pressure on wood resources in the India . Indian Ministry of Energy and Fuel estimates that 73% of wood comes from deforestation (non-renewable sources).Each stove reduces the equivalent of between 1.5 tons of carbon dioxide emissions annually. Reduces Carbon Monoxide, other harmful emissions and indoor air pollution level helps to manage their health of women living in rural area,