Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> http://www.scielo.org.za/rss.php?pid=1021-447X20100001&lang=es vol. 21 num. 1 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Energy savings opportunities at the University of Nigeria, Nsukka</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2010000100001&lng=es&nrm=iso&tlng=es This paper examines the potential for energy savings in Nigerian higher institutions with particular reference to the University of Nigeria, Nsukka. Electricity consumption and cost profiles for a period of 10 years indicate a steady rise attributable to marginal improvement in staff living standards, increasing students' enrolment, infrastructural development, preponderant use of inefficient electrical appliances and increasing business activities within the community. Investigations show that about 51% of the total electricity consumption occurs in staff housing units, 16% in students' hostels and the balance in academic and public buildings on the campus. An internal energy policy, awareness creation and establishment of an energy management unit in the University system are some of the measures that can guarantee good savings. This paper estimates electricity savings potentials of 10-20% in Nigerian higher institutions through well articulated and vigorously pursued energy efficiency programmes in the system. <![CDATA[<b>An analysis of energy consumption for a selection of countries in the Southern African Development Community</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2010000100002&lng=es&nrm=iso&tlng=es This paper examines the energy consumption, supply and resources of some of the countries in the Southern African Development Community (SADC) in 2005, the base year for this analysis. The region is rich in energy resources and currently enjoys relatively stable and affordable electricity. Except in the case of Botswana, Mauritius, Namibia and South Africa, final energy demand is dominated by the residential sector in the form of biomass. Energy consumption or final energy demand in Angola, Botswana, Mozambique, South Africa, Tanzania, Zambia and Zimbabwe is projected to 2030 using a Long Range Energy Alternatives Planning (LEAP) model in a 'business as usual' scenario, the other countries being left out because of poor quality data. The projections are carried out by relating historic sectoral GDP and population growth in each country to energy demand and then using the historical link and the projections of these drivers to project energy demand. The analysis under this 'business as usual' scenario seems to indicate that we can expect to see a large increase in consumption in these countries, especially in the form of biomass and electricity. In both cases, supply is a concern. Having established what the present resources are; what some of the supply elements are currently in place; what the base-year demand is; and some basic relationships between demand and socio-economic drivers, this paper sets the stage for further studies that include the future energy supply; regional trade; and scenario analysis using indicators of sustainable development for the region. However, further analysis of the regional energy system, is only valuable if it is supported by good data. A reliable energy balance is needed for the countries not modelled here, and in the case of the modelled countries, better data is also needed, especially in the use biomass. <![CDATA[<b>Evaluating the impact of consumer behaviour on the performance of domestic solar water heating systems in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2010000100003&lng=es&nrm=iso&tlng=es South Africa experienced a rapid expansion in the electric power consumer base after 1994 that was not matched by corresponding investment in the country's generation capacity. By the dawn of 2008, the situation had reached a critical point, with regular countrywide blackouts and load shedding and is expected to persist for several years, before the proposed new base stations can come online. Currently, 92% of the country's electricity is generated in coal-based power stations and are responsible for the country's heavy carbon footprint. Additionally this power must crisscross the country to distant load centres via an aging transmission infrastructure and in the process massive amounts of energy are lost particularly during peak power demand. Electricity consumption in South African households accounts for approximately 35% of peak demand, with water heating constituting 40% of that. The country has abundant sunshine and solar water heating technology and offers one of the most viable compiementary solutions to the country's energy and environmental crises. Moreover the location of the systems at the consumer end means that the need to upgrade the transmission infrastructure can also be differed. Application of technology alone however, may not necessarily result in the required energy savings particularly in cases of uninformed consumer usage. In this paper the authors evaluate the impact of consumer behaviour on the performance of domestic solar water heaters in South Africa and suggest measures that could be taken to optimize this performance. <![CDATA[<b>Use of artificial roughness to enhance heat transfer in solar air heaters - a review</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2010000100004&lng=es&nrm=iso&tlng=es Improvement in the thermo hydraulic performance of a solar air heater can be done by enhancing the heat transfer. In general, heat transfer enhancement techniques are divided into two groups: active and passive techniques. Providing an artificial roughness on a heat transferring surface is an effective passive heat transfer technique to enhance the rate of heat transfer to fluid flow. In this paper, reviews of various artificial roughness elements used as passive heat transfer techniques, in order to improve thermo hydraulic performance of a solar air heater, is done. The objective of this paper is to review various studies, in which different artificial roughness elements are used to enhance the heat transfer rate with little penalty of friction. Correlations developed by various researchers with the help of experimental results for heat transfer and friction factor for solar air heater ducts by taking different roughened surfaces geometries are given in tabular form. These correlations are used to predict the thermo hydraulic performance of solar air heaters having roughened ducts. The objective is to provide a detailed review on heat transfer enhancement by using an artificial roughness technique. This paper will be very helpful for the researchers who are researching new artificial roughness for solar air heater ducts to enhance the heat transfer rate and comparing with artificial roughness already studied by various researchers.