h i g h l i g h t s A concentrating PV/T solar collector with fluid-based spectral splitting filt... more h i g h l i g h t s A concentrating PV/T solar collector with fluid-based spectral splitting filter is tested. The oleylamine solution of Cu 9 S 5 nanoparticles is employed in the optical filter. The thermal energy exceeding 100°C are harvested by the collector.
Energy poverty is at its highest risk in Africa and yet introducing clean and modern energy in ru... more Energy poverty is at its highest risk in Africa and yet introducing clean and modern energy in rural Africa demands huge resource. Most African rural use biomass energy in traditional cook stoves. Similarly, Ethiopia’s rural are using traditional stoves with their associated risks. Injera, the highly consumed food in the country is the most energy intensive cooking activity. Authors’ previous researches have proved that it is possible to bake Injera by using solar stoves. However, optimization and safety issues need further study. This paper has focused on demonstrating safe and affordable indirect solar Injera stoves that considered end users economy, ergonomics and versatility of the system. Solar Injera stove with integrated latent heat storage gives good degree of freedom in terms of baking time. However, its high cost remained challenging to implement in rural communities. This research uses a sensible heat storage that lasts for about 30 minutes of baking and avoids the high c...
Proceedings of the ISES Solar World Congress 2015, 2016
Latent heat storage and efficient heat transport technology helps to utilize the intermittent sol... more Latent heat storage and efficient heat transport technology helps to utilize the intermittent solar energy for continuous and near isothermal applications. However, many latent heat storages face challenges of storage charging, heat retaining, and discharging the stored heat. This paper tries to address the challenges of heat transportation and storage charging-discharging issues. The heat transportation from the receiver over some distance, from outside to the kitchen, is carried out with a stainless pipeline and water as heat transfer fluids. However, the charging-discharging process is carried by conduction method with the help of fins. In addition, the stored heat is retained for about one-two days by using aerogel insulation. The latent heat is stored in a phase change material (PCM), nitrate salt (mixture of 60%NaNO3 and 40%KNO3), which melts at 222ºC and has 109 J/g specific heat of fusion. The storage has the capacity of storing up to 250ºC heat and supply this heat isothermally during baking in the liquid-solid phase transition. However, the sensible heat stored in the solid and liquid form of the PCM is used to perform additional applications that do not require uniform heat which includes bread baking, kita (large pancake) baking and water boiling. The low thermal conductivity of PCM is enhanced by using extended aluminum fins that are attached to the baking plate and extruded inward to the storage. In this paper, two-phase loop thermosyphon of steam is used to manage the long distance heat transportation required between the receiver (outside) and the storage (inside a house). The steam in the thermosyphon flow has restricted to a maximum working temperature of 250ºC. Steam is selected for its highest heat capacity, availability and stable nature. It carries heat from the collector focus point and condenses in a coiled pipe imbedded in aluminum plate placed on top of the storage. Many fins are solidly attached to this plate to conduct the heat down to the PCM inside the storage during charging. This design configuration avoids pressure development inside the PCM storage and the charging-discharging temperature is recorded in three zones (top, middle and bottom) of the storage. The experimental and numerical results show that the heat transportation, retention and charging-discharging methods are effective.
Ethiopia, the second most populated country in Africa, meets 96% of its energy need from bio-mass... more Ethiopia, 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 pancake like bread that is consumed by most of the population, demands a temperature of 180-220 o C 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 m 2 , 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 o C). 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.
The global shift towards renewable energy is manifested in developing countries such as Ethiopia ... more The global shift towards renewable energy is manifested in developing countries such as Ethiopia primarily because of continuous economic growth in the last two decades and secondly due to the vast untapped potential resources. In addition to other factors, the lack of accurate data of the resources has, however, hampered the development of solar energy technologies. The aim of this paper is to investigate the resource estimation by undertaking direct measurements at selected sites in the Northern part of Ethiopia. This paper presents an assessment of the solar energy resource based on the primary data collected between January 2011 and December 2012. The daily and monthly average global solar radiation is analyzed based on the 10 minute interval measurement retrieved from the data loggers. From the analysis it is seen that the measured values give a better accuracy and distribution of the global solar radiation than earlier Fig.s that were based on satellite images and model calculations. Furthermore, these results can be used to determine the solar resource potential of Northern Ethiopia for further energy development.
Ethiopia with a population of about 85 million meets 96% of its energy needs with bio-mass, charc... more 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. ...
In Ethiopia, like most developing countries, the majority of households depend on wood and charco... more In Ethiopia, like most developing countries, the majority of households depend on wood and charcoal as their cooking energy resources. This energy has a direct impact on the forest coverage and its emissions have significant health issues. Biogas technology has introduced to address these problems and reduce energy poverty in developing countries. However, the success of this technology depends on many factors such as technology appropriateness, available skill, proper introduction, and government support to create favorable financial incentives. The objective of this paper is to make an overview assessment of biogas development programs in Ethiopia, identify development barriers and provide suggestions to mitigate these barriers. The national and regional biogas program of Ethiopia has implemented to give energy for cooking and to some extent for lighting. However, it has shown limited success over the years. The National Biogas Programme of Ethiopia has shown an overall 50% achiev...
Additional information is available at the end of the article a glass bottle to avoid air traps. ... more Additional information is available at the end of the article a glass bottle to avoid air traps. The juice examined regularly in 30, 60 and 90 days for its PH, TSS and total microbial load. The results have shown the average total bacteria counts of the juices is below the maximum allowable limit in foods for consumption. Accordingly, the technology would enable smallholding farmers to start equitable agroprocessing.
The Injera baking electrical mitad is the most energy-consuming device in every household in Ethi... more 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 0 C. 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.
With the new advancements in vibration control strategies and controllable actuator manufacturing... more With the new advancements in vibration control strategies and controllable actuator manufacturing, semi-active actuators and dampers are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. This is attributed to the fact that in a semi-active system, the damping coefficients can be adjusted to improve ride comfort and road handling performances. The currently available semi-active damper technology uses MR fluid to control the damping characteristics of the suspension system. In addition to MR dampers, combining air springs in a semi-active suspension system leads to better handling and ride performance in vehicles. Furthermore, the use of air spring in semi-active suspension system helps to ease design of variable spring stiffness. This easy design opportunity leads to independent control of stiffness and ride height of the vehicle. This paper deals with the design and modelling of variable stiffness air spring for semi-active suspension system, modelling of semi-active suspension systems with variable stiffness and MR damper, and study their
Today, many developing countries are using biomass as their primary energy supply. However, this ... more Today, many developing countries are using biomass as their primary energy supply. However, this energy affects the environment, health and safety of women and children. In addition, utilization of this energy using traditional cooking stoves is causing indoor air pollution and in turn health problems to millions of people. To overcome such problems, efforts are being made by researchers globally and are suggesting alternative safe energy sources. This paper demonstrates solar cooker with an integrated PCM thermal storage and heat transportation loop system suitable for high temperature applications. The system has designed to address Injera baking application. Injera, a fermented flat bread type, is the most common food type served three to four times a day in Ethiopia. Other countries like Eritrea, Somalia, Sudan and Yemen also use this food. The storage system has storing capacity of heat up to 250 0 C and it can retain this heat for about two days. The storage has coupled to a polar mounted concentrator, fixed receiver and used steam heat transfer fluid. The steam circulates naturally between the evaporator and condenser in a closed loop. The paper focuses on indirect charging, simultaneous charging-discharging and discharging of the stored heat for the purpose of Injera baking. The frying pan is a custom-made aluminum plate casted by embedding a 10mm coiled stainless steel steam pipe as heating element. The pan is 500mm in diameter and 30mm thick; and the fins are 20mm in diameter and 140mm long. The fins have immersed into a 20kg PCM, which is coupled to a 1.8m diameter parabolic dish collector. The solar fryer demonstrates Injera baking for average family size. Baking is tested from the stored heat, while storage is charging. A fully charged storage has supplied enough heat to baked average household Injera demands about 19Injeras and additional breads with the remaining heat.
Many of today's solar cookers lack energy storage and their applications have been limited to... more Many of today's solar cookers lack energy storage and their applications have been limited to day time use while the sun is shining. In addition these cookers need longer cooking time and are less versatile to users compared with the traditional wood stoves. This article presents tests of a solar stove with and integrated heat storage designed to satisfy a particular need of some east African countries to bake their daily food (Injera). The prototype was tested in the solar laboratories at NTNU and Mekelle University, and presented for community demonstrations in Mekelle. Steam is used as heat carrier between a receiver in the focal point of a concentrating dish and a solar salt based latent heat storage. The stored heat enables users to bake at any time. The storage has a capacity to retain usable thermal energy for about one to two days depending on the amount of insulation. This system can supplement the existing electric and biomass Injera stoves and provide inexpensive and clean energy solution for food preparation. Solar baking provides benefits in terms of human health, environmental strain and high costs associated with biomass fuel.
This paper deals with a performance evaluation of locally made 20L batch type reactor and JP and ... more This paper deals with a performance evaluation of locally made 20L batch type reactor and JP and AM biodiesels produced by using this reactor. The inputs for transesterification process were Jatropha and Argemone Mexicana oils, with an alcohol to oil molar ratio of 6:1, 1% NaOH catalyst, 55 °C reaction temperature, an hour settling time and 600 rpm agitation speed. The conversion ability of the reactor for Jatropha and Argemone Mexicana oil seeds has shown a 94% and 94.5%, respectively. The property of these biodiesels has analyzed and its result was within the limit of ASTM D6751. Performance and emission behavior of different blends of these oils such as B10, B20, B30 and pure diesel were evaluated in a single cylinder, four stroke CI engine with rated speed of 1500 rpm and rated power of 4 kW. The B10 blend has shown closer characteristics in terms of specific fuel consumption, brake thermal efficiency and exhaust gas temperature at different loads to diesel. On the other hand, B10 has resulted with higher CO 2 and CO and lower NOx emission potential compared to the two blends. The lower NO 2 emission is due to its lowest exhaust gas temperature. The biodiesels finally pass standard tests of EPE by fulfilling the standard parameters that made them competitive and substitute options to diesel fuel.
Proper sterilization of reusable medical devices and surgical instruments are critical aspects of... more Proper sterilization of reusable medical devices and surgical instruments are critical aspects of modern health care delivery system that can also directly affect the patients. In off grid health centers and health posts, solar autoclave can have great contribution to facilitate modern heath care delivery by sterilizing medical infected equipment and reduces associated health risks. This research has developed a solar thermal based autoclave and analyzed its performance. The numerical and experimental results have validated with standard sterilization techniques and show successful and efficient results. The laboratory and community trial of the autoclave achieved temperatures of about 145°C and it was maintained it for more than 20 minutes that complies the sterilization process and procedures that has proved by the sterilization monitoring techniques. The field trial of the system was an encouraging comment to promote the technology and disseminate the technology.
h i g h l i g h t s A concentrating PV/T solar collector with fluid-based spectral splitting filt... more h i g h l i g h t s A concentrating PV/T solar collector with fluid-based spectral splitting filter is tested. The oleylamine solution of Cu 9 S 5 nanoparticles is employed in the optical filter. The thermal energy exceeding 100°C are harvested by the collector.
Energy poverty is at its highest risk in Africa and yet introducing clean and modern energy in ru... more Energy poverty is at its highest risk in Africa and yet introducing clean and modern energy in rural Africa demands huge resource. Most African rural use biomass energy in traditional cook stoves. Similarly, Ethiopia’s rural are using traditional stoves with their associated risks. Injera, the highly consumed food in the country is the most energy intensive cooking activity. Authors’ previous researches have proved that it is possible to bake Injera by using solar stoves. However, optimization and safety issues need further study. This paper has focused on demonstrating safe and affordable indirect solar Injera stoves that considered end users economy, ergonomics and versatility of the system. Solar Injera stove with integrated latent heat storage gives good degree of freedom in terms of baking time. However, its high cost remained challenging to implement in rural communities. This research uses a sensible heat storage that lasts for about 30 minutes of baking and avoids the high c...
Proceedings of the ISES Solar World Congress 2015, 2016
Latent heat storage and efficient heat transport technology helps to utilize the intermittent sol... more Latent heat storage and efficient heat transport technology helps to utilize the intermittent solar energy for continuous and near isothermal applications. However, many latent heat storages face challenges of storage charging, heat retaining, and discharging the stored heat. This paper tries to address the challenges of heat transportation and storage charging-discharging issues. The heat transportation from the receiver over some distance, from outside to the kitchen, is carried out with a stainless pipeline and water as heat transfer fluids. However, the charging-discharging process is carried by conduction method with the help of fins. In addition, the stored heat is retained for about one-two days by using aerogel insulation. The latent heat is stored in a phase change material (PCM), nitrate salt (mixture of 60%NaNO3 and 40%KNO3), which melts at 222ºC and has 109 J/g specific heat of fusion. The storage has the capacity of storing up to 250ºC heat and supply this heat isothermally during baking in the liquid-solid phase transition. However, the sensible heat stored in the solid and liquid form of the PCM is used to perform additional applications that do not require uniform heat which includes bread baking, kita (large pancake) baking and water boiling. The low thermal conductivity of PCM is enhanced by using extended aluminum fins that are attached to the baking plate and extruded inward to the storage. In this paper, two-phase loop thermosyphon of steam is used to manage the long distance heat transportation required between the receiver (outside) and the storage (inside a house). The steam in the thermosyphon flow has restricted to a maximum working temperature of 250ºC. Steam is selected for its highest heat capacity, availability and stable nature. It carries heat from the collector focus point and condenses in a coiled pipe imbedded in aluminum plate placed on top of the storage. Many fins are solidly attached to this plate to conduct the heat down to the PCM inside the storage during charging. This design configuration avoids pressure development inside the PCM storage and the charging-discharging temperature is recorded in three zones (top, middle and bottom) of the storage. The experimental and numerical results show that the heat transportation, retention and charging-discharging methods are effective.
Ethiopia, the second most populated country in Africa, meets 96% of its energy need from bio-mass... more Ethiopia, 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 pancake like bread that is consumed by most of the population, demands a temperature of 180-220 o C 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 m 2 , 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 o C). 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.
The global shift towards renewable energy is manifested in developing countries such as Ethiopia ... more The global shift towards renewable energy is manifested in developing countries such as Ethiopia primarily because of continuous economic growth in the last two decades and secondly due to the vast untapped potential resources. In addition to other factors, the lack of accurate data of the resources has, however, hampered the development of solar energy technologies. The aim of this paper is to investigate the resource estimation by undertaking direct measurements at selected sites in the Northern part of Ethiopia. This paper presents an assessment of the solar energy resource based on the primary data collected between January 2011 and December 2012. The daily and monthly average global solar radiation is analyzed based on the 10 minute interval measurement retrieved from the data loggers. From the analysis it is seen that the measured values give a better accuracy and distribution of the global solar radiation than earlier Fig.s that were based on satellite images and model calculations. Furthermore, these results can be used to determine the solar resource potential of Northern Ethiopia for further energy development.
Ethiopia with a population of about 85 million meets 96% of its energy needs with bio-mass, charc... more 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. ...
In Ethiopia, like most developing countries, the majority of households depend on wood and charco... more In Ethiopia, like most developing countries, the majority of households depend on wood and charcoal as their cooking energy resources. This energy has a direct impact on the forest coverage and its emissions have significant health issues. Biogas technology has introduced to address these problems and reduce energy poverty in developing countries. However, the success of this technology depends on many factors such as technology appropriateness, available skill, proper introduction, and government support to create favorable financial incentives. The objective of this paper is to make an overview assessment of biogas development programs in Ethiopia, identify development barriers and provide suggestions to mitigate these barriers. The national and regional biogas program of Ethiopia has implemented to give energy for cooking and to some extent for lighting. However, it has shown limited success over the years. The National Biogas Programme of Ethiopia has shown an overall 50% achiev...
Additional information is available at the end of the article a glass bottle to avoid air traps. ... more Additional information is available at the end of the article a glass bottle to avoid air traps. The juice examined regularly in 30, 60 and 90 days for its PH, TSS and total microbial load. The results have shown the average total bacteria counts of the juices is below the maximum allowable limit in foods for consumption. Accordingly, the technology would enable smallholding farmers to start equitable agroprocessing.
The Injera baking electrical mitad is the most energy-consuming device in every household in Ethi... more 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 0 C. 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.
With the new advancements in vibration control strategies and controllable actuator manufacturing... more With the new advancements in vibration control strategies and controllable actuator manufacturing, semi-active actuators and dampers are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. This is attributed to the fact that in a semi-active system, the damping coefficients can be adjusted to improve ride comfort and road handling performances. The currently available semi-active damper technology uses MR fluid to control the damping characteristics of the suspension system. In addition to MR dampers, combining air springs in a semi-active suspension system leads to better handling and ride performance in vehicles. Furthermore, the use of air spring in semi-active suspension system helps to ease design of variable spring stiffness. This easy design opportunity leads to independent control of stiffness and ride height of the vehicle. This paper deals with the design and modelling of variable stiffness air spring for semi-active suspension system, modelling of semi-active suspension systems with variable stiffness and MR damper, and study their
Today, many developing countries are using biomass as their primary energy supply. However, this ... more Today, many developing countries are using biomass as their primary energy supply. However, this energy affects the environment, health and safety of women and children. In addition, utilization of this energy using traditional cooking stoves is causing indoor air pollution and in turn health problems to millions of people. To overcome such problems, efforts are being made by researchers globally and are suggesting alternative safe energy sources. This paper demonstrates solar cooker with an integrated PCM thermal storage and heat transportation loop system suitable for high temperature applications. The system has designed to address Injera baking application. Injera, a fermented flat bread type, is the most common food type served three to four times a day in Ethiopia. Other countries like Eritrea, Somalia, Sudan and Yemen also use this food. The storage system has storing capacity of heat up to 250 0 C and it can retain this heat for about two days. The storage has coupled to a polar mounted concentrator, fixed receiver and used steam heat transfer fluid. The steam circulates naturally between the evaporator and condenser in a closed loop. The paper focuses on indirect charging, simultaneous charging-discharging and discharging of the stored heat for the purpose of Injera baking. The frying pan is a custom-made aluminum plate casted by embedding a 10mm coiled stainless steel steam pipe as heating element. The pan is 500mm in diameter and 30mm thick; and the fins are 20mm in diameter and 140mm long. The fins have immersed into a 20kg PCM, which is coupled to a 1.8m diameter parabolic dish collector. The solar fryer demonstrates Injera baking for average family size. Baking is tested from the stored heat, while storage is charging. A fully charged storage has supplied enough heat to baked average household Injera demands about 19Injeras and additional breads with the remaining heat.
Many of today's solar cookers lack energy storage and their applications have been limited to... more Many of today's solar cookers lack energy storage and their applications have been limited to day time use while the sun is shining. In addition these cookers need longer cooking time and are less versatile to users compared with the traditional wood stoves. This article presents tests of a solar stove with and integrated heat storage designed to satisfy a particular need of some east African countries to bake their daily food (Injera). The prototype was tested in the solar laboratories at NTNU and Mekelle University, and presented for community demonstrations in Mekelle. Steam is used as heat carrier between a receiver in the focal point of a concentrating dish and a solar salt based latent heat storage. The stored heat enables users to bake at any time. The storage has a capacity to retain usable thermal energy for about one to two days depending on the amount of insulation. This system can supplement the existing electric and biomass Injera stoves and provide inexpensive and clean energy solution for food preparation. Solar baking provides benefits in terms of human health, environmental strain and high costs associated with biomass fuel.
This paper deals with a performance evaluation of locally made 20L batch type reactor and JP and ... more This paper deals with a performance evaluation of locally made 20L batch type reactor and JP and AM biodiesels produced by using this reactor. The inputs for transesterification process were Jatropha and Argemone Mexicana oils, with an alcohol to oil molar ratio of 6:1, 1% NaOH catalyst, 55 °C reaction temperature, an hour settling time and 600 rpm agitation speed. The conversion ability of the reactor for Jatropha and Argemone Mexicana oil seeds has shown a 94% and 94.5%, respectively. The property of these biodiesels has analyzed and its result was within the limit of ASTM D6751. Performance and emission behavior of different blends of these oils such as B10, B20, B30 and pure diesel were evaluated in a single cylinder, four stroke CI engine with rated speed of 1500 rpm and rated power of 4 kW. The B10 blend has shown closer characteristics in terms of specific fuel consumption, brake thermal efficiency and exhaust gas temperature at different loads to diesel. On the other hand, B10 has resulted with higher CO 2 and CO and lower NOx emission potential compared to the two blends. The lower NO 2 emission is due to its lowest exhaust gas temperature. The biodiesels finally pass standard tests of EPE by fulfilling the standard parameters that made them competitive and substitute options to diesel fuel.
Proper sterilization of reusable medical devices and surgical instruments are critical aspects of... more Proper sterilization of reusable medical devices and surgical instruments are critical aspects of modern health care delivery system that can also directly affect the patients. In off grid health centers and health posts, solar autoclave can have great contribution to facilitate modern heath care delivery by sterilizing medical infected equipment and reduces associated health risks. This research has developed a solar thermal based autoclave and analyzed its performance. The numerical and experimental results have validated with standard sterilization techniques and show successful and efficient results. The laboratory and community trial of the autoclave achieved temperatures of about 145°C and it was maintained it for more than 20 minutes that complies the sterilization process and procedures that has proved by the sterilization monitoring techniques. The field trial of the system was an encouraging comment to promote the technology and disseminate the technology.
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Papers by Asfafaw Tesfay