Renewable Energy Sources and their Application Editors R.K. Behl, R.N. Chhibar, S. Jain, V.P. Bahl, N.El Bassam
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Chapter 31 Design and Development of Energy Efficient Improved Biomass Sigri (Grill) for Roasting of Fresh Maize Cobs for Sikkim and NEH regions A. K.Mishra, Surajit Murasingh and Ravi Gupta College of Agricultural Engineering and Post-Harvest Technology, Ranipool, Sikkim, India
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[email protected] ABSTRACT Biomass grill has been developed and evaluated for roasting green maize cobs for saving in fuel. The biomass fuel viz. wood charcoal, charcoal briquettes and small cut pieces of wood has been used for direct heat supplement to the maize cobs. The energy efficient grill saves time and fuel for roasting 4-6 maize cobs at a time. The grill consisted of roasting chamber, fuel tray, top fuel grit with covering lid to retain heat inside to control thermal losses and manual air blower for initial burning of fuel. The thermal efficiency of grill varied between 28-31% compared with traditional method used having very low thermal efficiency varied 6-8%. This resulted in efficient roasting leading at higher output. Improved biomass grill was helpful to conserve forest biomass for saving 60-70% fuel with smokeless environment, time and less fuel storage space. The improved smokeless biomass grill has been used for cooking food, boiling water and roasting/baking of vegetables and other. Keywords: Biomass, Grill, Roasting, Maize cobs, efficiency 1.
INTRODUCTION
A Grill is a device for cooking food by applying direct heat through burning fuel for roasting. This study is an attempt to design and develop an improved type of Sigri (Grill) for the roasting of freshly harvested maize cobs to conserve forest fuel wood, human drudgery and smokeless environment for health. Maize or corn (Zea mays) is a plant belonging to the family of grasses (Poaceae). It is cultivated globally being one of the most important cereal crops worldwide. The maize crop is harvested (Fig.1) after normal maturity with the objective to remove maize cob and straw without loss. Optimum harvesting moisture content for maize is 25-35% (w.b). Harvesting of the maize crop is traditionally done by manual methods of using a plain sickle. In Sikkim the maize is one of the most important cereal crops during the Kharif (rainy/summer) season as rain fed crop. The season starts with February-march and ends with JulySeptember depending upon the altitude. It is grown over an area of about 36,000-40,000 hectare which is about 35-40% of total cultivable area. The production of maize was recorded 16,500 tonnes during 1970 – 1980, 64890 t in 2006 – 07(FSAD Annual Progress Report -2006-07) and increased more than 75000 t as cash crop in the region. Maize cobs roasted in fire pits (Fig.2), was the main business during the season as cash crop to earn money which involves village women’s in Sikkim. More than 60 people selling roasted maize along the highway between 9th mile and 32nd mile in June till September under temporary sheds smoking and roasting maize in his fire pits. The forest department of Sikkim provides special permit to the maize sellers to setup their sheds and for the use of forest wood on the recommendation of the village Panchayet. Farmers purchase green maize cobs @ Rs5.0 per piece and sell about 150 to 200 numbers roasted maize cobs @Rs10.0 per piece at road sides of NH-31A connecting Gangtok, Sikkim from Siliguri, West Bengal to the tourists since morning 6am to evening 6pm. (A- Maiz-ing story, Sikkim Express daily). In season, freshly roasted bhutta or corn on the cob, daubed with a mix of lemon, salt and chilli, is the most tempting street food. For roasting they use high volume of forest wood near the road sides. The loose fuel wood emits high level of smoke in and around the areas. There is no control for burning of fuel and large amount of fuel wood wastes in ideal burning when there was a no sale of roasted maize cobs that was 20-60 minutes without use. Thus the design and development of energy efficient improved biomass Sigri for roasting of freshly harvested maize cobs (Shown in Figure 1) will be highly beneficial to the people of Sikkim and others parts of hilly region where the green cobs are consumed extensively as the main food both in the roasted and steamed forms.
Figure 1 Fresh maize cob for sale This study reveals in its effectiveness and efficiency over the conventional method of direct roasting in open flame as shown in Figure 2. It is seen that the improved Sigri is found to be more economical than the conventional method by savings in fuel storage space and 60-70% less fuel with high output to enhance income by selling roasted cobs along the road side.
Figure 2 Traditional practice for roasting cobs 2.
MATERIAL AND METHOD
The design and fabrication of improved biomass grill was developed and fabricated in the workshop of Division of Farm Power at College of Agricultural Engineering and Post-Harvest technology (CAU), Gangtok, Sikkim. The Testing was carried out in the laboratory of AICRP on Renewable Sources of Energy (RES) at CAEPHT, Gangtok. The Sigri was portable and could be used at any location for testing and demonstration at rural areas of Sikkim. 2.1 Design of the Improved Sigri
A study was carried out on a prototype improved stove (Sigri) for roasting of multi-cobs of maize along with the possible solution. These possible solutions are as follows:1. A movable biomass Tray (with wood handle). 2. A manual operated Blower. 3. A movable ash tray. 4. Air control valve. 5. Insulation with (clay/soil). And the possible design was drawn in the AutoCAD software along with the parameters, as shown in Figure 3-5.
40 Top cover/ lid 2ф Mesh(2.5x2.5) 7.5
Storage chamber (Roasted maize)
2 Roasting chamber 9.5
Grill (6mm ф) Movable Charcoal tray
60 Handle 15 Plenum chamber 2 4 Air valve 20
5 10ф 15
1
8
Blower
2 4
4
20 Handle 16
Movable ash tray
Fig. Sigri for freshly harvested maize cobs (all dimensions in cm)
Figure 3 Design for the improved biomass Stove (Sigri)
Figure 4 CAD design of Energy Efficient Improved Bio-mass Stove (Sigri) with components
Figure 5 Prototype design of improved sigri for roasting of fresh green maize cobs
The prototype design (Figure 5) was prepared and one unit of improved design was fabricated at college workshop. The required material for fabrication of prototype was purchased from local market. Total cost of fabrication of improved Sigri was Rs 2450.00 per unit including input material cost, fabrication cost and Rs.850.0 as cost of hand blower. 2.2 Description of the Sigri (Grill)
A Grill is a device for cooking food by applying heat directly from below. Charcoal Grill uses either charcoal briquettes or all-natural lump charcoal as their fuel source. The charcoal, when burned, will transform into embers radiating the heat necessary to cook food. Use of charcoal and briquettes emphasize the uniformity in size, burn rate, heat creation and quality exemplified by briquettes. These Sigris are primarily designed for the farmers who are in the business of selling roasted maize cob along the highways in the hilly region. 2.3 Developed Sigri
Table1. Dimensions and construction details of improved Sigri Cross sectional area of Sigri
400×400 mm2
Height of Sigri
600mm
Lead size and thickess
400×400mm2 and 1mm
Insulation
Insulite-7 inside
Upper garte for wood charcoal Grate type
Rectangular
Dimension
400×400 mm2
Material
MS rod of Ø3 mm
Handle
Wood
Size
10×10 mm2
Tray for burning charcoal Type
Rectangular
Dimension
400×400 mm2
Material
MS rod of Ø3 mm
Grate for burning of charcoal Type
Rectangular
Material
MS rod of Ø3 mm
Size
100×12 mm2
Dimension
400×400 mm2
Ash tray Type
Rectangular
Matreial
GI sheet
400×400 mm2
Dimension Blower Type
Cetrifugal type, air tight
Power source
Manual
Gas outlet
Ø5 mm, 12 nos, 50mm below the top of Sigri
Air inlet
Ø10 mm, 4nos, above 70mm from bottom of Sigri
2.4 Testing of Sigri (Grill):
Survey was conducted at the Radong and Namin, village of East Sikkim during the peak season of selling of roasted maize cob. There were 15-20 numbers of temporary sheds/ stalls engaged for selling of roasted green maize cobs over fuel woods burnt in open pits under smoky environments. Required Data has been collected as: Cost of green maize cob: 5.00/piece Cost of fuel wood: 5.00/kg Cost of end product: 10.00/piece Sale period: 6 am to 6 pm Cost of wood charcoal: 10.00/kg (Singtam) Cost of hand made briquette: 5.00/kg (Charcoal dust+Rice husk+cow dung) The unit was tested to roast green maize cobs with wood charcoal and briquettes. The designed prototype saves fuel for roasting of fresh maize cobs with low emission of smoke @ 4 maize cobs at a time. A hand blower was connected at bottom for initial ignition of fuel. The unit consumes 1.0 kg wood charcoal to roast 25-30 green cobs per hour. The improved Stove (Figure 6) was demonstrated on Radong village for roasting of fresh maize cobs. Freshly harvested green Maize cobs during the first three weeks of June used for the sale as raw milky soft sweet maize cobs either boiling over the top compartment of improved Sigri in boiling water or roasting in grill compartment. The Burning capacity of fuel, heat utilised and power output rating was determined as per standard test procedure and guidelines of Indian Standard on Solid Biomass for Chulha-Specification IS 13152.
Figure 6 Testing of improved stove / grills for roasting of green maize cobs 3.
RESULT AND DISCUSSION
Improved sigri was developed and tested in laboratory as well as at local people place, used for roasting the fresh maize cobs in open fire as discussed in section 3. The findings in terms of comparative performance of Improved Stove (grill) for roasting green cob with traditional and Improved Stove / Grill are presented in Table 2.
Table 2: Comparative performance of Improved Stove (Grill) Traditional Practices Parameter
Improved stove (Grill)
Fire wood
Wood- charcoal
Briquette
Roasting cost per cob
0.85
0.27
0.30
Fuel used per cob (g)
28
28
63
Cost of green cob
750
750
750
300
120
90
Input Cost per day(150 cob)
1050
870
840
Profit per day
450
630
660
Net Profit per month
13500
18900
19800
Calorific value
2950
6930
3266
08-10
20-23
18-21
1800
360
540
(150 numbers) Fuel cost
(150No’s)
Kcal/kg Thermal efficiency,% (Average) Fuel Consume per Month (kg).
The analysis showed that roasting 150 numbers of green cobs in improved stove (grill) saves 1800 kg of fuel wood. The increase in profit after sale of roasted cob @Rs 660.00 per day is to pay benefits to farmer as Rs 19800.00 per month. The cost of roasted cobs was Rs 10.0 per cob using home-made briquettes prepared from wood charcoal left over after use as by product of traditional chulha in rural areas. The cost of roasting reduced to Rs 0.30-0.40 compared with fuel wood as shown in figure 7. The benefit cost ratio of improved stove was 1.47 times with increase of 26% profit on sale of roasted maize cobs for the income generation.
Figure 7 Saving of fuel cost and net profit with wood charcoal & briquettes 4. CONCLUSSION In Sikkim and others parts of North Eastern hilly region the green maize cobs are consumed extensively in the roasted and steamed forms. This design was beneficial to the people dependent on maize growing
areas to earn money by selling roasted or steamed cobs in season. Energy efficient design increases profit after sale and saves forest wood used for roasting in high volume and requires less storage space for fuel with clean smokeless environment. 5. Acknowledgements The authors are thankful to AICRP on RES for providing the financial assistance to carry out the research work, Department of Farm Power, CAEPHT (CAU), Gangtok, Sikkim and to the Central Agricultural University, Imphal, India for providing the facilities. We also acknowledge with thanks to M Kalpana Devi research scholar at IIT Kharagpur for her contribution in this research and also we are thankful to Prof. K. N. Dewangan and Sonu Kumar, NERIST- Itanagar, India for the critical comments and invaluable suggestions.
REFRENCES
A-Maize-ing Story an Article, Published on SIKKIM Express Daily newspaper published from Gangtok Dated. 16/06/2011. (http://www.sikkimexpress.com) Annual Progress Report -2006-07, Food Security and Agriculture Development Department, Govt. of Sikkim. Indian Standard on Solid Biomass for Chulha-Specification IS 13152, Published on 16/06/2011. http://www.sikkimexpress.com. http://sikkimagrisnet.org/General/en/Maize.aspx http://en.wikipedia.org/wiki/Barbecue_grill
