http://ir.haramaya.edu.et//hru/handle/123456789/216 2026-04-17T16:16:38Z 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 http://ir.haramaya.edu.et//hru/handle/123456789/7987 EXPLORING MICROPHYSICAL AND OPTICAL PROPERTIES OF AEROSOLS, AND ESTIMATING AEROSOL OPTICAL DEPTH USING METEOROLOGICAL PARAMETERS USING MULTI- SPECTRAL SENSORS OVER DIRE DAWA, ETHIOPIA Teshager Argaw Endale; (PhD) Getachew Abebe Argaw; (PhD) Bedada Wereka Aerosols influence climate by altering the global energy balance via scattering and absorbing solar radiation (direct effects), and by their effect on the reflectance of clouds and occurrence of precipitation (indirect effects). Aerosols also influence biogeochemical cycles, lead to diminished environmental visibility, and harm human health. Aerosols in the urban regions have a unique character because the amount of emitted aerosol species can vary significantly in terms of number density, season and location when compared to aerosols in remote continental and maritime regions. They have a distinct character as they can exhibit significant seasonal and inter annual variability owing to variations in local emissions and long-range transport. This thesis focuses on advancing knowledge of critical properties of aerosols, specifically microphysical and optical properties, which govern the role of aerosols in climatic and environmental change. The study’s main aim is to investigate the long-term variation of Aerosol Optical Depth (AOD). It also aims to develop a mathematical model to estimate AOD using combined meteorological parameters, and to assess the status of air quality over Dire Dawa, and to identify the possible sources of the aerosols using a HYSPLIT model. Remote sensing data provide a better understanding of aerosol characteristics at a large scale and are available in a wide range, while ground-based observation is very limited. In this study, we used multi-year remote sensing, namely, MODIS-Aqua, MODIS-Terra, MISR, and OMI satellite retrievals, OPAC aerosol model, and AERONET AOD data, to evaluate and identify the best and suitable satellite sensor which can retrieve AOD, to explore the trend and distribution of AOD, and to examine the status of air quality over a semi-arid region Dire Dawa in the period from 2009 to 2020. The result obtained show that the AOD values were observed to be higher in summer (June to August) than during the rest of the months due to the predominance of coarse dust and sea salt particles and possibly also due to the higher water vapor content of the atmosphere due to high summer temperatures, which encourages the growth of aerosols. In addition, the air quality status over Dire Dawa during the study period was moderate as measured by purple sensor and gravimetric method. Generally, AOD values vary from season to season due to aerosol’s optical and microphysical properties being affected by anthropogenic sources, natural sources, meteorological conditions and surface albedo. The ii study also strongly recommends to make use of a synergy of remote sensing and ground installed devices such as sun-photometer to monitor the status of air qualit 144p. 2023-12-01T00:00:00Z