Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> http://www.scielo.org.za/rss.php?pid=1021-447X20130003&lang=es vol. 24 num. 3 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Solar radiation analysis and regression coefficients for the Vhembe Region, Limpopo Province, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000300001&lng=es&nrm=iso&tlng=es Given the limited observed and reliable data for solar irradiance in rural parts in South Africa, a correlation equation of the Angström-Prescott linear type has been used to estimate the regression coefficients in the Vhembe District, Limpopo Province, South Africa. Five stations were selected for the study, with the greatest distance between stations less than 180 km. Monthly regression coefficients were derived for each station based on an observation dataset of sunshine duration hours and global horizontal irradiance. The correlation coefficients appear to be above 0.9. The representative Angström-Prescott model for the Vhembe Region was found by collating the data for each station and then averaging the respective correlation coefficients. This paper presents the generated regression coefficients for each station and for the Vhembe Region. <![CDATA[<b>Exergy analysis of a flat plate solar collector</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000300002&lng=es&nrm=iso&tlng=es In this study, exergetic performance analysis of flat plate solar collector has been carried out analytically. A comprehensive mathematical modelling of thermal performance is simulated using MATLAB simulink and optimal geometrical and thermody-namic parameters are predicted pertaining to optimum performance of the system. The optimization procedure was applied to a typical collector and the optimum design points were extracted. The optimum values of collector inlet temperature, mass flow rate, absorber plate area, and fluid outlet temperature for maximum exergy inflow from the system have been obtained. <![CDATA[<b>Small hydropower in southern Africa - an overview of five countries in the region</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000300003&lng=es&nrm=iso&tlng=es This paper looks at the status of small hydropower in Lesotho, Mozambique, South Africa, Swaziland and Zimbabwe. For each country, an overview will be given of the electricity sector and the role of hydropower, the potential for small hydropower and the expected future of this technology. Small hydropower has played an important role in the history of providing electricity in the region. After a period with limited interest in applications of small hydropower, in all five countries, a range of stakeholders from policy makers to developers are showing a renewed interest in small hydropower. Although different models were followed, all five countries covered in the paper do currently see activities around grid connected small scale hydropower. Particular frameworks that facilitate IPPs and Power Purchase Agreements with the national utility do provide a basis for (local) commercial banks to provide finance. Off-grid hydropower for rural electrification purposes sees activities in the countries with an active (support) role of government in this respect only. Small hydropower, renewable energy technology has large potential across the southern Africa region, both for grid connected and off-grid applications. Historically, small hydropower played an important role in the development of the region. Since the mid-1960s, however, the main emphasis has been on centralised fossil fuel-based electricity generation. Developers and policy makers have only recently begun looking at small hydropower again. <![CDATA[<b>Operational evaluation of the performance of a solar powered absorption system in Pretoria</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000300004&lng=es&nrm=iso&tlng=es A 35kW pilot solar powered absorption cooling system was designed and constructed at Moot Hospital in Pretoria to investigate the technical and economic performance of the technology. Technically, the system produced an estimated 43.938MWh of cooling energy per year and reached a maximum power of 31kW and operated with an average COP of 0.63, which compares favourably with the 0.7 given by the manufacturer. This system has since been decommissioned. Unfortunately, due to a lack of standard design and operation information, the system was overdesigned. As a result, the economic performance of this technology could not be accurately determined. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2013000300005&lng=es&nrm=iso&tlng=es