http://ir.haramaya.edu.et//hru/handle/123456789/119 2026-05-22T20:21:44Z http://ir.haramaya.edu.et//hru/handle/123456789/8454 Comparisons of Influences of Mass Densities of Fuel Briquettes Produced from Eucalyptus, Olive Tree, Sorghum Stalk and Khat Waste Raw Materials On Burning Times Amente (Prof), Gelana; Mengistu (PhD), Birhanu; KASSAHUN, WONDWOSEN Global energy demand is rising, causing overexploitation of fossil fuels and environmental challenges. Renewable sources, especially biomass briquettes from residues, offer sustainable alternatives. Ethiopia relies heavily on unsustainable biomass, leading to deforestation and degradation. The rising demand for household energy in Ethiopia has intensified reliance on fuelwood and charcoal, contributing to deforestation and environmental degradation. This study investigates the potential of four locally available biomass raw materials Eucalyptus, Olive tree, Sorghum stalk, and Khat waste—for briquette production. Raw materials (20 kg each) were chopped, air-dried, and carbonized under limited oxygen to produce char powder. The resulting char was mixed with 10% clay binder and water, molded into cylindrical briquettes, and oven-dried. Performance tests were conducted using the water boiling method, measuring density, burning temperature, and effective cooking times. Results revealed significant differences in density and effective cooking time among the briquette types. Khat and Olive tree briquettes exhibited higher densities (0.442 and 0.476 g/cm³) and sustained heating, maintaining water temperatures above 75°C for 101 and 73 minutes, respectively. Sorghum briquettes showed the highest peak temperature (96°C) but had short endurance (40 minutes), while Eucalyptus briquettes demonstrated the lowest density and inconsistent burning behavior, averaging only 31 minutes above 75°C. ANOVA confirmed significant differences (p < 0.05) among treatments, indicating that raw material type strongly influences briquette performance. The findings suggest that Khat waste and Olive tree residues are the most promising biomass feed stocks for producing efficient and sustainable fuel briquettes in Ethiopia, offering a renewable alternative to fuel wood and charcoal while addressing waste management and deforestation concerns. 42 2025-01-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8376 EVALUATION OF EXTENDED COOKING USING SOLAR PLATE THERMAL BOX FILLED WITH DIFFERENT TYPES OF HEAT RETAINERS AND METAL SCRAPS SELAM SEYOUM MENGISTU; Gelana Amente (Professor) One of the biggest and most important domestic tasks is cooking. In rural areas it is usually, it is done over open flames using fuels like firewood, charcoal, dung, and agricultural waste. An alternative way to minimize fuel wood is using solar power. In this study, a solar thermal box was used to complete cooking a food that had already been partially cooked (boiled) using a fire. The solar plate utilized in the study was constructed like a thermal box, actually partitioned into six parts to facilitate the conduction of several tests at once. The word used for this device is a solar thermal box (STB). This investigation tested three cooking scenarios. The purpose of the study was to compare the temperature and cooking time differences between a normal hotbox/haybox and STB, STB assisted with heat retainers, and finally, STB with heat retainer assisted with scrap metals to enhance thermal energy transfer to the heat retainers. The food (rice) to be placed in the STB was originally boiled using a fire source. The results of the study indicate a linear increment of temperature with the use of solar plates. The inclusion of heat retainers managed to finish cooking the rice from 65 to 73 minutes faster and with more flavor than the rice in the haybox. The addition of metal scraps with heat retainers improved the cooking time by 38–49 minutes faster. Thus, overall, the solar plate with heat retainer and metal scraps has improved the cooking time by 53-54% compared to that of haybox. The results showed that solar power alone did not significantly increase food temperature, but the inclusion of heat retainers and later metal scrapes significantly improved the cooking time. Future work may focus on the use of STB-assisted heat retainers and conducting materials as a solar cooker of food without the need for initial boiling by using other heat sources. 60 2024-09-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8331 EVALUATION OF EXTENDED COOKING USING SOLAR PLATE THERMAL BOX FILLED WITH DIFFERENT TYPES OF HEAT RETAINERS AND METAL SCRAPS SELAM SEYOUM MENGISTU; Gelana Amente (Professor) One of the biggest and most important domestic tasks is cooking. In rural areas it is usually, it is done over open flames using fuels like firewood, charcoal, dung, and agricultural waste. An alternative way to minimize fuel wood is using solar power. In this study, a solar thermal box was used to complete cooking a food that had already been partially cooked (boiled) using a fire. The solar plate utilized in the study was constructed like a thermal box, actually partitioned into six parts to facilitate the conduction of several tests at once. The word used for this device is a solar thermal box (STB). This investigation tested three cooking scenarios. The purpose of the study was to compare the temperature and cooking time differences between a normal hotbox/haybox and STB, STB assisted with heat retainers, and finally, STB with heat retainer assisted with scrap metals to enhance thermal energy transfer to the heat retainers. The food (rice) to be placed in the STB was originally boiled using a fire source. The results of the study indicate a linear increment of temperature with the use of solar plates. The inclusion of heat retainers managed to finish cooking the rice from 65 to 73 minutes faster and with more flavor than the rice in the haybox. The addition of metal scraps with heat retainers improved the cooking time by 38–49 minutes faster. Thus, overall, the solar plate with heat retainer and metal scraps has improved the cooking time by 53-54% compared to that of haybox. The results showed that solar power alone did not significantly increase food temperature, but the inclusion of heat retainers and later metal scrapes significantly improved the cooking time. Future work may focus on the use of STB-assisted heat retainers and conducting materials as a solar cooker of food without the need for initial boiling by using other heat sources. 60 2024-09-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/8314 EFFECTS OF SECONDARY AIR INLETS OF DIFFERENT HOLE PATTERNS ON WOOD BURNING COOKSTOVE PERFORMANCE NAJWAR ABDULWEHAB; Galena Amente (Prof.) Billions of households worldwide cook using biomass fires and suffer from the toxic smoke emitted into their homes. Laboratory studies of wood-burning cookstoves demonstrate that secondary air injection can greatly reduce the emission of harmful air pollution, but these experimental advancements are not easily translated into practical cookstove designs that can be widely adopted. This study was conducted at Haramaya University on four designed and constructed sleeves of different secondary air inlets hole patterns (two circular, one spiral shape and one of vertical). In the study five wood burning cookstoves were used, four with secondary air inlet inner sleeves and one without inner sleeve (control). Comparisons were made in terms of onset of cooking and effective cooking times. The findings indicate no benefit of secondary air inlet in terms of onset of cooking. However, there is a glimpse that secondary air inlet at a proper location (but not too close to the rim or the bottom of the pot) can positively impact effective cooking time. In the current study the proper distance was 3 cm from the rim. More studies are required to pinpoint the exact location by trying distance such as 0.5 cm up to 3 cm. additional tests could also be done by varying the diameters of the secondary inlet holes. 47 2024-12-01T00:00:00Z