Energy consumption performance analysis of electrical mitad at Mekelle City

The Injera baking electrical mitad is the most energy-consuming device in every household in Ethiopia. This research presents a detail engineering study on the energy-consumption performance of existing electrical mitad in Mekelle city. The research work considered thirty-one electrical mitad from different workshops in Mekelle. Depending on the number of clay used, there are three types of electrical mitad; the single clay, the double clay and the rotating type mitad. In this research, it was found out that the average power consumption of existing mitad is in the range of 3.5 KW to 3.9 KW. The specific average baking energy is 0.82, 0.73 and 0.54 kWh/kg of injera for double clay, single clay and rotating type mitad respectively while the thermal efficiency by considering baking of 6kg of Injera on each mitad is 38%, 47% and 61% respectively. In all designs, the baking temperature is in the range of 130-140 0C. Although the rotating type mitad is more energy efficient, it has technical limitations. Due to that, the single and the double clay mitad are widely used by households hence share all the market penetration of injera baking electrical mitad. These commonly used electrical mitad have an energy loss from 50-60% of the input energy.Keywords: Electrical mitad, Injera baking energy, Thermal efficiency, Baking temperature, Ethioopi

Theoretical and Experimental Comparison of Box Solar Cookers with and without Internal Reflector

AbstractBox solar cookers are commonly built with internal sheet metal painted black as an absorber. In order to increase the performance, a design which incorporates internal reflection is proposed in this paper. The aim of this paper is to report comparisons made between box solar cookers with and without internal reflector. Theoretical modelling of the two types of cookers has been made by considering the radiation, convection and conduction heat transfer employing the thermal network method. The theoretical analysis made was based on steady state heat transfer analysis of the cookers. Experimental comparisons were also made on two cookers having the same aperture area and made from the same type of materials except the internal absorber. The tests were made as per the American Society of Agricultural Engineers (ASAE) procedure.The result of the theoretical analysis predicts that the performance will be higher in the cooker with internal reflector than the same cooker without reflector. The steady state analysis shows that for the cooker with reflection the temperature of the bottom absorber plate is higher than the cooker without reflector. Similarly, results of dry test and water boiling test show better performance by the cooker with reflector. The standard stagnation temperature and the cooking power were higher in the cooker with reflector as compared to the cooker without reflector. In conclusion, the performance of box solar cookers can be enhanced by making appropriate angle side walls of the absorber and providing internal reflection

Excess Energy from PV-Battery System Installations: A Case of Rural Health Center in Tigray, Ethiopia

PV-Battery systems are commonly sized based on the lowest solar radiation of the site of implementation. This implies that during days of high solar radiation excess energy is available. This study investigated the potential of excess energy for thermal storage from PV systems for a case of a rural health center. The system components of a typical PV installation in a rural health center in Tigray, Ethiopia, were considered. The electricity load profile of the health center and solar radiation data available from Mekelle city were used as inputs to a TRNSYS model. Analysis of excess energy in the system at hourly and ten-minute time intervals was conducted. The analysis results indicate that during the months from September to May excess energy was available that could be thermally stored and utilized. During these months, the excess peak power ranged from 737 to 841 W and daily average excess energy ranged from 2070 to 2959 Wh. In contrast, in the months from June to August, no excess energy was available due to low solar radiation

Design and Development of Solar Thermal Injera Baking: Steam Based Direct Baking

AbstractEthiopia, the second most populated country in Africa, meets 96% of its energy need from bio-mass and majority of this energy goes entirely to Injera baking. Injera, a pan-cake like bread that is consumed by most of the population, demands a temperature of 180-220 oC to be well baked. Both traditional and newly developed biomass Injera stoves are energy inefficient; besides the kitchen environment is highly polluted with soot and smoke that affect the health of household inhabitants. This article introduces new technology that enables Injera baking using indirect solar stove. A parabolic dish with an aperture area of 2.54 m2, a well-insulated stainless steel pipe of 10mm, a coiled stainless steel heat exchanger, a pressure relief valve and three gate valves were equipped in the system and K-type thermocouples were used to record the temperature. The heat transfer process has been governed by the principle of natural circulation boiling-condensation between receiver and stove. A preset pressure relief valve is used to control the self-circulating working heat transfer fluid (steam at a temperature of 250 oC). The system was developed and tested for steam based direct baking in the same fashion as the traditional Injera stove. In this experiment, heat transport without significant loss from the receiver for baking at some distance is demonstrated. The challenge with manual tracking and direct steam based baking model indicates the performance of the technology can be improved. It can also win more acceptances if it is equipped with auto trackers and heat storage mechanism. In conclusion, unlike previous efforts, the experiment demonstrated that a high temperature indirect baking of Injera is possible

Improved Cook Stoves to Meet Sustainable Development Goal in Ethiopia

The 2030 sustainable development goal (SDG7) target progress indicators show that developing countries are off track. Ethiopia’s low performance to the SDG7 has endangered its economic, societal, and environmental sustainability. The performance in clean cooking has contested its policy, institutional setup, and R&D. The objective of this paper lies in evaluating four improved cook stoves against a traditional stove based on fuel consumption, cooking time, and emission. The study would contribute to solving the clean-cooking challenges by giving scientific evidence on the technological status of these stoves. The evaluation results show that the TCS consumed 2.7 kg of fuel, had a cooking time of 1:30 h, and used 4.3 kg CO2 per cooking period. Similarly, the ICSs required: 1.2 kg, 2 h, and 1.9 kg (EZY); 1.5 kg, 3 h, and 2.4 kg (Tikikkle); and 1.4 kg, 5 h, and 3.2 kg (Lakech), respectively. In addition, these stoves registered a thermal efficiency of 25, 17, and 19%, respectively. The metal body, insulation, and air inlet caused EZY to perform better. However, these technologies are low-order technologies, and their performance is found to be a major locking factor in ICS adoption. This evidence would help ICS actors to understand where to intervene for better adoption. Furthermore, the authors gave implementation fix recommendations to improve ICS programs

Mechanical and water-absorption properties of sisal fiber (Agave sisalana)-reinforced polyester composite

Mechanical and water-absorption properties of composites made from sisal fiber and polyester matrix have been investigated. Test specimens were prepared with untreated fiber and treated with alkaline solution of sodium hydroxide. The amount of fiber content in the composites varied with values of 10%, 20%, and 30% by volume. The test results indicate that the alkaline treatment has improved the tensile, compressive, and impact strength of the composite with the added benefit of low water absorption. The impact strength is found to increase with an increase in the fiber content. However, the tensile and compressive strengths have decreased; water-absorption rate has increased with an increase in the fiber content

Effect of Carbon and Glass Fillers on Tensile and Impact Strength, Water Absorption, and Degradation Properties of Sisal/Polyester Composites

The inferior mechanical and water absorption properties of natural fibers are massive challenges to utilizing them for industrial applications. The study aims to enhance tensile strength, impact strength, water absorption, and degradation of sisal/polyester composites using glass and carbon fillers. Four fillers proportions (2.5 wt.%, 5 wt.%, 7.5 wt.%, 10 wt.%) and two sisal fiber proportions (20 wt.% and 30 wt.%) were taken to fabricate the composites. Experimentations were performed according to the ASTM standards. The fillers improved tensile and impact strength, water absorption, and degradation of the composites. Carbon-filled composites displayed better results than the corresponding glass-filled composites. Carbon fillers showed a maximum increment of 24.2% in tensile and 78.5% in impact strength for the dry 20/80 composites, and 14.7% in tensile and 57.3% in impact strength for the dry 30/70 composites. Moreover, carbon fillers reduced water absorption by 55.4% for the 20/80 composites and by 53.6% for the 30/70 composites. The highest values of tensile and impact strengths were obtained for the 5 wt.% carbon-filled 30/70 composite; whereas, the lowest water absorption was for the 10 wt.% carbon-filled 20/80 composite. The lowest degradation of 2% in tensile and impact strengths was exhibited for the 7.5 wt.% carbon-filled 20/80 composites

Solar Powered Heat Storage for Injera Baking

Ethiopia with a population of about 85 million meets 96% of its energy needs with bio-mass, charcoal, wood, animal dung and plant residues. More than 50% of this energy goes entirely on baking Injera. Injera the national food of the country demands 180-220 °C to be well cooked. In this article; Injera baking with solar energy on off-focus system, status of electric powered stove and the potential for solar powered stoves is discussed. The research and development of solar thermal for household energy consumption has not been well developed and adopted. One reason for this is that the system can only be used outdoor and at time of sun shine. In addition to the off-focus solar thermal application this paper discussed the integration of solar thermal with heat storage for a sustainable future use. The prototype for direct steam based baking was developed and tested in Mekelle University (Ethiopia) and Phase change material based heat storage prototype was developed and tested at NTNU. Both experiments showed the possibility of solar energy for Injera baking and its sustainability by including latent heat storage. This research gave hope to break the bottleneck related with on- focus solar cooker