Eco-Stove research and development in North-East Nigeria

Transcription

1 Scholarly Journal of Science Research and Essay Vol. 7(3), pp June 2018 Available online ISSN Scholarly-Journals Full Length Research Paper Eco-Stove research and development in North-East Nigeria Mohammed, A.H.* 1 and Zainab, B.M. 2 1 Center for Arid Zone Studies, University of Maiduguri. PMB 1069, Maiduguri. Borno State 2 Department of Creative Arts, University of Maiduguri, PMB 1069, Maiduguri. Borno State Accepter 23 May, 2018 Development, fabrication and dissemination of an improved Eco-stove was conducted in 2017 The focused is on incorporation of insulation around the combustion chamber to reduce conduction heat loss across the walls of the chamber and provision of spacious air inlet to ensure the availability of sufficient air for the complete combustion of the charcoal. Water boiling test result showed the improved Eco-stove reached a temperature of o C after 20 minutes, whereas the conventional charcoal stove reached a temperature of o C after 20 minutes. Thus, the water boiling test results show that the Eco-stove stove has a thermal efficiency of 7.64 %, indicating better performance compared to conventional stove. The overall quantity of charcoal consumed by the five households that use Eco-stove for the period of the research trial is kg compared to kg of charcoal used by the households that used conventional stove. That shows there is 16.0 % reduction in consumption of charcoal if Eco-stove is used compared to conventional stove. This observation reflected squarely on the amount of money expended on purchase of the fuel. Less amount of money is expended on purchase of charcoal when using the Eco-stove compared to the conventional stove. Regarding smoke and soot emission, it was observed that there was virtually complete combustion when using the Ecostove. This is because enough air entered the combustion chamber through the wide air inlet and therefore minimal or no smoke was produced. The improvements made on the Eco-stove compared to the conventional stove in providing insulation using kaolin around the combustion chamber and sizable air inlet to admit adequate quantity of air for combustion, and redesigning the pattern of the pot seat, have all 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 Eco-stove stove, compared to the conventional stove making it to be more user-friendly in health, comfort and convenience. Further modifications focused at redesigning the combustion chamber 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 programmed for the future. Key words: Charcoal stove, combustion chamber, insulation, smoke rings, thermal efficiency, chimney, smokiness, fuel consumption. INTRODUCTION Fighting climate change and improving the health of Nigeria s women are often seen as competing priorities, yet some technologies address both tasks simultaneously. One technology is among the cheapest methods of achieving both and this is; improved cook *Corresponding author s auwal@unimaid.edu.ng stoves. (World Bank. 2011; PoA-DD, 2014). Almost 70% - 80% of Nigeria s 170 million people, eat food cooked on fires and stoves burning wood, charcoal, straw, husks, dung etc (World Bank. 2011; PoA-DD, 2014). Conventional three stone open fire stoves make kitchens and other cooking areas death traps for the Nigeria s most vulnerable people; women and small children (Ayo, 2009). Pollution levels from smoke and gases such as carbon monoxide are typically hundreds of times those

2 Scholarly J. Sci. Res. and Essay 36 that would be tolerated in the streets or a factory. Many women die annually as a result, including children under five, mostly victims of childhood pneumonia. Other problems involve in use of the in-efficient rudimentary 3 stone open fire cook stoves amongst others are; health hazards among women and children, deforestation, drought & desertification and other climatic changes. Numerous studies both within and outside Nigeria have shown that improved stoves are the best solution to all these problems (World Bank. 2011; Ayo, 2009). A well fabricated improved stove is expected to be clean burning and fuel-efficient. This means that improved stoves are expected to be more efficient than conventional three stones open fires stoves being used in most homes at present in Nigeria. For this reason, several research and development works have been conducted on the stove design and fabrication of improved stoves. A few examples efforts made on improvement of cooking stoves are as follows; The Angethi stove, the Improved Vented Mud stove (IVM) in India, Kilakala stove in Tanzania, the Kenya Ceramic Jiko (KCJ), stove, Improved Wood Stove developed in Minna, Nigeria and many others. However, many of these improved stoves have some problems facing them and/or faced when using them thus, reducing their full acceptability by the people. For instance, the Angethi stove which uses charcoal, is fabricated with galvanized iron bucket, mud/concrete, and grate has a thermal efficiency of only 17.5%, (Wazir, 1981). The Improved Vented Mud (IVM) stove, also called the Nada Chula, developed in India has thermal efficiency values of 10 to 23.5% (Pal and Joshi, 1989). The Kilakala stove, developed at the Sokoine University, Tanzania, is a mud stove built using locally available materials. It has a fuel saving capacity of 30% (Crewe 1990, Otiti 1991). One of the major disadvantages of the stove was that it did not provide sufficient illumination (Otiti 1991). The Kenya Ceramic Jiko (KCJ), one of the most successful urban stove projects in the Eastern African region, is reported to have average thermal efficiency of about % of the heat generated, (Kammen and Fayemi Kammen 1992) However, it can be clearly observed from these various stove improvement efforts, there remains a lot of room for improvement on the level of achievements. Therefore, the aim of the present work is to increase the efficiency of the existing improved cook stoves. The specific objectives are as follows; (i.) expansion of the air inlet to allow entry of sufficient air for maximum combustion, (ii.) incorporate kaolin insulating material around the combustion chamber to further reduce the amount of heat loss by radiation and, (iii.) to carefully design the pot seat in order to reduce heat lost by convection from top of the stove. MATERIALS AND METHOD Eco-stove Research, Development and Construction Site: Research, development and construction of the Ecostoves was conducted at Metal-works and Welding Section of Center for Entrepreneurship and Enterprise Development (CEED), University of Maiduguri. The work was conducted with active collaboration, suggestions and assistance of the staff of CEED. Procurement of Materials, Design Description and Construction of the Eco-stove The size of the Eco-stove is determined using the size of the cooking pot/saucepan that will be used for cooking in it. The cooking pot/saucepan capacity is therefore the first thing that considered when constructing the Ecostove. The Eco-stove is fabricated from widely available and standardized metal sheeting, angle iron, bar and/or tubing. The metals were procured as follows; Mild steel and kaolin used for construction of six (6) units of the Eco-stove were purchased on 3 rd August, 2017 from stores within Maiduguri metropolitan. These materials include; twenty square.meter (20 M 2 ) of smooth surfaced mild-steel sheet (2.0 mm), six square meter (6M 2 ) of roughed surfaced mild-steel sheet (2.0 mm), ten meters (10 M) angled iron bar, five meters of iron rod, and kaolin for insulation. Six units of conventional stoves were obtained for comparison with the fabricated Eco-stoves. All other tools for metal work and welding such as welding arc and rods, pick hammer, angle grinder, driving chisel, file for smoothing metal edges, compass for drawing circles, try square for confirming right-angled corners, anvil (or equivalent) platform for hammering etc. were obtained from CEED. Construction (metalwork) of Eco-stoves The Eco-stove is designed to be of dual fuel utilization. It can be put There are number of marked differences in the Eco-stove constructed from the one presented in the proposal. This difference is as a result of widespread consultations and suggestions sought from experts on heat generation and transfer. Consultations is made from staff of Departments of Physics, Mechanical Engineering, CEED and some members of the public on how to construct an energy efficient, cost-effective and acceptable stove. Each of the six (6) units of the Eco-stove constructed are replica of one another. Each comprises of eight (8)

3 Mohammed and Zainab 37 Figure 1: Design of the Circular Base Plate distinct parts. Seven (7) are entirely constructed from metal and welded jointly together. The only non-metallic exception is the kaolin insulator material that is loaded in powdered form into a hollow crevice made in between the stove frame and the combustion chamber. These 8 parts are namely; The circular top plate/ stove collar, a pair stove handles, main stove frame (stove body), two pairs of pot stand/support, retractable charcoal tray, the tray handle, two (2) rails onto which the charcoal tray rest, the stove base (i.e. stove stand) and the kaolin (insulator) material. The size of the stove is determined by the size of the pots, sauce pans and other containers that will be used for cooking on it. Therefore, sizes of the containers to be used on the stove is the first thing that was determined in the construction of the stove, Circular Stove Collar/Chimney: This is the top most part of the stove, where waste heat and smoke is expelled. It is fabricated from smooth surfaced mild-steel sheet (2.0 mm). It measures 45 cm in diameter and 11 meters in height. It houses the pot during cooking and ensures that heat is channeled into the cooking pot and protects the flame from being blown off by breeze during windy days if the cooking is done outdoors. Circular Base Plate The circular base-plate forms the base of the Circular Stove Collar/Chimney. In the centre of the base plate a 14cm x 14cm square hole which is cut from the centre using an angle grinder or hammer and chisel (Figure 1). Circular Base Plate is welded under the stove collar and sits directly on top the stove frame (Figure 2). It is fabricated from smooth surfaced mild-steel sheet (2.0 mm). It has a measurement of 45cm in diameter. It serve as a support to the four (4) pot supports, and also the 2 handles for lifting the stove are attached directly to it.. In the center of the Circular Plate a 23cm x 23cm square hole is cut using hammer and chisel. (iii.) Stove Frame This is the main body of the stove. It measures 30 cm (length) x 30 cm (width) x 33cm (height). It is fabricated from smooth surfaced mild-steel sheet (2.0 mm). It sit directly on top the stove stand/base. It is completely covered in three sides and opened only to the front of the stove. It is made of double casing, with inner and outer walls, with a crevice in between the wall into which the kaolin insulator material is loaded. It serve as an insulator combustion chamber and prevent the heat from escape (iv.) Air inlet and air flow An air inlet with a vertical and horizontal dimensions of 15.5 cm and 30.0 cm respectively was constructed. This gives an area of air inlet of 465 cm 2 which provides enough room for passage of air to enable optimum combustion of the fuel in the combustion chamber. (v.) Combustion Chamber (CC) The combustion chamber (CC) is where the initial combustion of the fuel takes place and the fuel is burned. All sides of the CC are well insulated to conserve the heat and made in a sloped manner to improve the distribution of air around the fuel. The CC is constructed in a way that is dual purpose for use both for charcoal

4 Scholarly J. Sci. Res. and Essay 38 Figure 2: Position of the Circular Stove Collar/Chimney relative to the Circular Base Plate Figure 3: The Eco-stove fuel (charcoal) tray and firewood. In addition, 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 before it proceeds to be ejected out through the chimney. 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.

5 Mohammed and Zainab 39 Figure 4: Front view of the improved Eco-stove Figure 5: Sideview of the Ecostove. (vi.) Stove Handles A pair of hard and sturdy handles to be used for lifting the Eco-stove measuring 21.5 cm are constructed using iron bar. The handles are welded to the side of the Eco-stove main frame directly under the circular base plate. (vii.) Charcoal Tray Rack (CTR) The CTR is made of double walls for containing the charcoal. The square outer wall of the tray is of size 21 cm X 21 cm served as a quasi-insulator and an inner rectangular wall of size 14.5 cm

6 Scholarly J. Sci. Res. and Essay 40 Figure 6: Top view of the Eco-stove Both outer and inner walls of the CTR are constructed from 2mm toughened steel metal rectangle formed into in a cylinder. It is fabricated from rough surfaced mild-steel sheet (2.0 mm). The CTR is fabricated to ensure the fuel is burnt efficiently in the Eco-Stove. The tray is not welded to the Eco-Stove, it is retractable (can be drawn in and out) so that it can be removed to allow easy cleaning. It has a handle made of steel bar attached to it. (viii.) Stove Base and Support Bracket The base (i.e. stove stand) which measures 45 cm X 45 cm is constructed from 3 mm angle iron bar. by 16 cm serve as the container for charcoal. DATA COLLECTION AND ANALYSIS DATA COLLECTION Water Boiling Test Water boiling test is conducted with the aim of comparing the time taken to boil same quantity of water by the improved Eco-stove and the conventional stove. Two stoves, an Eco-stove and a conventional stove and two pots were thoroughly cleaned and dried. The test was conducted in an enclosed room environment. Same type and amount of charcoal was weighed out for each type of stove. It was therefore ensured that there was sufficiently same environment and material used for each stove, stored in the same place so as to have uniform material content. The pot, lid, and thermocouple were weighed and recorded. Afterwards, one liter of water at a temperature of 32 o C was added to the two pots and weighed again to determine the weight of the water. This was repeated for each test. Charcoal weighed at 250 g was introduced into the combustion chamber of both Ecostove and conventional stove and about 15ml of kerosene was sprinkled on it to initiate burning. The 2 pots were placed on the stove the moment the sprinkled kerosene got burnt out. The time of the day, the environmental conditions (ambient temperature) and the initial temperature of the water were recorded. A thermometer was inserted in to each of the two pots on the two different stoves. Thereafter the commencement

7 Mohammed and Zainab 41 of the test the temperature of the water was recorded at intervals of two (2) minutes until the moment the water came to a vigorous boil. The pot was then removed from the two stoves and the fire immediately put out with the help of dry sand. This experiment is repeated twice and the temperature changes after intervals of two minutes were recorded. Experiment on Fuel Utility and Cost Prototypes of six improved Eco-stoves were developed, constructed and disseminated to six families. Conventional un-improved stoves that serve as control were also disseminated to six families. Number of persons per family to collect either the Eco-stove or the conventional stove range from six to thirteen persons. Each of the family that collected either Eco-stove or conventional stove were allocated 100 grams of charcoal of the same type, origin and moisture content to use in cooking their meals. Data was taken of the quantity of charcoal used per meal (breakfast/lunch/dinner) per day. Data on the quantity of charcoal used per meal per day is converted into monetary values and recorded. DATA ANALYSIS Data collected were subjected to analysis of variance (ANOVA). Means obtained are separated using Fisher s Least Significant Difference (LSD) at 5 % level of significance (P = 0.05). Data were analysed using Statistix Data Analytical Soft Ware for Researchers. Version 10. Tallahassee, FL, USA. REULTS AND DISCUSSION Water boiling test result showed on Table 1 and depicted on Figure 7 revealed that the improved Eco-stove reached a temperature of o C after 20 minutes, whereas the conventional charcoal stove reached a temperature of o C after 20 minutes. Thus, the water boiling test results showed that the Eco-stove stove has a thermal efficiency of 7.64 % compared to un-improved conventional stove. This, succinctly indicates a better performance of the Eco-stove when compared to the conventional stove. The enhanced performance can be attributed to many factors elucidated below. First, the kaolin 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 and extended to the bottom of the cooking pot. The second 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. In addition, there is also the third factor of availability of sufficient air that ensures the complete combustion of the fuel wood. The Eco-stove design keeps the cooking pot in contact with the fire over the largest possible surface area to improve the efficiency of the stove. Although the collar will limit the Eco-stove to one size of pot. The cooking pot collar is used to create a narrow channel which forces hot fire air to flow along the bottom and sides of the cooking pot. The Eco-stoves are able to achieve a very high degree of heat transfer to the cooking pot because the stove s circular collar/chimney which channels the heat from the charcoal/firewood directly to the surface area of the cooking pot. By using less charcoal Eco-stove reduce expenses and environmental impacts. Air Inlet and Air Flow are constructed in order to increasing the flow of the right amount of air which helps the fire burn hotter and helps to improve the burring of the fuel. The opening into the fire (fuel magazine), the size of the spaces within the stove through which hot air flows, and the chimney are all constructed of approximately the same size (i.e. constant cross sectional area). As the charcoal burns within the combustion chamber air is drawn into the combustion chamber. This will help to maintain a good draft throughout the Eco-stove keeping the fire hot. The right amount of incoming air helps the fire burn cleanly. The consumption rate of charcoal as depicted on Figure 8 showed Eco-stove (represented in brown bars) to be less in all household except one, compared to conventional stove (represented in blue bars) which consume more quantity of charcoal. The overall quantity of charcoal consumed by the five households that use Eco-stove for the period of the research trial is kg compared to kg of charcoal used by the households that used conventional stove. That shows there is 16.0 % reduction in consumption of charcoal if Eco-stove is used compared to conventional stove. This observation reflected squarely on the amount of money expended on purchase of the fuel. Less amount of money is expended on purchase of charcoal when using the Eco-stove compared to the conventional stove as showed on Figure 9. The observed less consumption of fuel by the Ecostove, is because its design, mainly the kaolin-insulator combustion chamber, enables approximately 70-80% of the heat from the stove to enter the cooking pot. With a conventional stove only about 10% to 40% of the released heat makes it into the pot. Improving the heat transfer from the fuel to the cooking pot saves significant amounts of fuel and ultimately reduce the overall cost of the charcoal.

8 Charcoal Quantity (Grams) Temperature (Degree Centigrade) Scholarly J. Sci. Res. and Essay 42 Table 1: Water boiling Test comparative analysis for improved and conventional stoves S/No Time in minutes Conventional stove (Water temperature in o C) Improved stove (Water temperature in o C) Note: Each figure is a mean of three figures recorded Quantity of water = 1 liter; Fuel type and quantity: Charcoal at 250 g Container type and sizes: Mild steel containers; size 280 mm height X 220 mm diameter Operating condition: Under same ambient temperature, humidity, solar radiation etc. Rate of Temperature Rise for Boiling Water Time (Minutes) Con Stove Ecostove Column1 Figure 7: Rate of temperature rise for boiling water Charcoal Consumption Rate for Conventional & Ecostove Trial 1 trial 2 Trial 3 Trial 4 Trial 5 Number of trials (Respondents) conducted Con. Stove Ecostove Column1 Figure 8: Charcoal consumption rate for conventional and eco-stove

9 Money Expended (in Naira) Mohammed and Zainab 43 Money Expended on Charcoal for Conventional & Ecostove Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Number of Trials (Respondents) Contacted Con. Stove Ecostove Column1 Figure 9: Money expended on charcoal for conventional and Eco-Stove CONCLUSION The improvements made on the Eco-stove compared to the conventional stove in providing insulation using kaolin around the combustion chamber and sizable air inlet to admit adequate quantity of air for combustion, and redesigning the pattern of the pot seat, have all 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 Ecostove stove, compared to the conventional stove making it to be more user-friendly in health, comfort and convenience. Further modifications focused at redesigning the combustion chamber 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 programmed for the future. Bryden, M., Still, D., Scott, P., Hoffa, G., Ogle, D., Bailis, R. and Goyer, K. (2014). Design Principles for Wood Burning Cook Stoves. or%20wood%20burning%20cookstoves.pdf Joseph, S.K., Krishna, P. and Van der Zann, H.B. (1990). Bringing stoves to the people. ACTS Press and the Foundation for Wood Stove Dissemination (FWD), Nairobi, Kenya. Pal, R.C. and Joshi, V. (1989). Improved cook stoves for household energy management - a case study. Productivity 30(1): World Health Organization (WHO) (1992). Geneva, Switzerland. TERI Evaluation of performance of cookstoves with regard to thermal efficiency and emissions from combustion. Tata Energy Research Institute (TERI), New Delhi, India. Tran, H.C.; and White, R.H Yawas, D.S. (2003). Performance evaluation of an improved threeburner wood fired stove. Nigerian Soc. Engineers Technical Trans. 38(3): Wazir, S REFERENCES Ayo, S.A. (2009). Design, Construction and Testing of an Improved Wood Stove. AU J.T. 13(1):12-18 (Jul. 2009). pdf Barnard, G.W. and Moss, P.A. (1982). Biomass for energy in the developing countries. Pergamon Press, Oxford, England.