Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> vol. 19 num. 4 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>A car air-conditioning system based on an absorption refrigeration cycle using energy from exhaust gas of an internal combustion engine</b>]]> Energy from the exhaust gas of an internal combustion engine is used to power an absorption refrigeration system to air-condition an ordinary passenger car. The theoretical design is verified by a unit that is tested under both laboratory and road-test conditions. For the latter, the unit is installed in a Nissan 1400 truck and the results indicate a successful prototype and encouraging prospects for future development. <![CDATA[<b>Evaluating the costs and achievable benefits of extending technologies for uneconomical coal resources in South Africa: The case of underground coal gasification</b>]]> As the South African economy relies heavily on its coal resources, these resources should be utilised and managed in the best possible manner. Underground coal gasification (UCG) is one of the leading technologies used where conventional mining techniques are uneconomical. UCG delivers gas suitable for synthesis, production of fuels and electricity, or for home usage. The method is perceived as being environmentally friendly and safer than traditional mining. The study summarised in this paper was conducted so as to create a simple model that would allow for the evaluation of UCG process-related costs versus expected benefits in a wider context and under different circumstances. The parameters of the model are: feasibility definition, i.e. maximum possible gas calorific value, based on geological surveys and gasification agents for a predefined need; direct process-related costs that are derived from the expected capital and operational expenditures and compared to the value and volume of the gas produced; and assessment of externality costs, i.e. the indirect economic value of environmental, safety and health benefits. The externalities concept should encourage governmental agencies to consider further investment in UCG technology as a vehicle for delivering, potentially, high savings in terms of the reduction in the costs of environmental damage resulting from gaseous emissions into the atmosphere, specifically expenditure on national health. <![CDATA[<b>Performance analysis for flat plate collector with and without porous media</b>]]> The present work involves a theoretical study to investigate the effect of mass flow rate, flow channel depth and collector length on the system thermal performance and pressure drop through the collector with and without porous medium. The solution procedure is performed for flat plate collector in single and double flow mode. The analysis of the results at the same configuration and parameters shows that the system thermal efficiency increases by 10-12% in double flow mode than single flow due to the increased of heat removal, and increase by 8% after using porous medium in the lower channel as a result of the increase of heat transfer area. At the same time the pressure drop will be increased. All collectors show improved efficiency obtained when the collector operates at relatively high flow rates, and at relatively low collector temperature rise since the collector losses will be less in low temperature difference. <![CDATA[<b>The impacts of climate change on food security and health in Southern Africa</b>]]> Climate change will have a great impact on Southern Africa according to the IPCC. Two closely related topics, food security and health will be affected by the changes in many ways. Difficulties in transporting food through carbon regulations in airfreight, changing conditions for growing food crops and negative impacts on fishery might occur and will very possible lead to an increase in malnutrition in the region. Changes of the climate will also have an effect on the way illnesses are transmitted and cause a number of extreme weather events which can have an extremely damaging consequence on human living. Two main efforts are being work on in terms of dealing with these concerns. At the international, regional and national levels, adaptation and mitigation action is being planned and implemented. Activities at each level are discussed and I argue this in this paper that currently the most efficient way of dealing with the existing and future burdens of climate change impacts are activities at a national level, and enhanced effort has to be made to improve regional and international collaboration in addressing these issues.