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Abstract: Solar energy technology is an option for energy saving in building air conditioning. A theoretical investigation of an open cycle solar air cooling system using aqueous Lithium Chloride solution as liquid desiccant is presented in this paper. The purpose of this work is to analyze the influences of both internal loads and external forcing, on the studied system by developing a computational code related to its mathematical model. The simulation results justify the choice of the system design. Indeed, it was highlighted that the higher is the outdoor temperature; the better is the coefficient of performance (COP) of the system. Furthermore, a global sensitivity analysis of the system model, achieved using Fourier Amplitude Sensitivity Test method, allowed us to identify the most influential factors that were ranked in a decreasing order of their influence degree on the system COP. Hence, key factors to be controlled for improving the system overall performance are specified. Keywords: Solar air conditioner, open cycle, lithium chloride, simulation, global sensitivity analysis, FAST method, complex system.Download Full Article |
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Abstract: Lithium-air (Li-air) battery is a promising electrochemical system with unprecedented high energy density. However, many problems and challenges prevent its wide scale application and commercialization. Low oxygen diffusion rates and large voltage gap are two of the main problems in Li-air battery. These two problems are related to the materials used in the air cathode such as porous carbon materials and metallic catalysts. This review seeks to discuss various materials used in the air cathode for Li air batteries. Mechanism of reaction in air cathode will be elucidated and discussed. Keywords: Carbon material, porosity, capacity, catalyst, round-trip efficiency.Download Full Article |
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Abstract: This study examined the socio-economic and environmental impact of the adoption of gasfier stoves by households in Arusha and Moshi towns in Tanzania. A total of 55 respondents were selected purposely from the gasfier stoves. For comparative purposes another 55 charcoal users were selected randomly for interview making a total sample of 110. There were also focus group consultations and key informant interviews. Structured and semi-structured questionnaires were used to collect data, which were analysed using the Statistical Package for Social Sciences. The results show that the respondents who were using gasfier stoves had significant reduction (p=0.001) in the cost of energy for cooking compared to charcoal stove users by spending only T.shs 13,396 per month compared to T.shs 36,932 for charcoal users. The use of gasfier stoves also had a positive impact on the environment. Findings show that by using gasfier stoves 15.4 ha were saved from deforestation per annum and about 365.4.tonnes of carbon were saved for sequestration an act that reduces carbon emissions and global warming. Nevertheless, despite the impressive performance of gasfier stoves for cooking, the rate of adoption has remained low. The main reason for this was reported to be the high price, poor quality of the pellets and unfriendly usability. The adoption of gasfier stoves could only be enhanced by addressing these constraining factors. Keywords: Gasfier stoves, economic and environmental benefits, Tanzania, Sub-Saharan Africa.Download Full Article |