Journal of Energy in Southern Africa最新文献_第10页

Non-linear multivariate models for estimating global solar radiation received across five cities in South Africa 估算南非五个城市接收的全球太阳辐射的非线性多元模型

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2019-05-16 DOI: 10.17159/2413-3051/2019/V30I2A6076

T. Govindasamy, N. Chetty

{"title":"Non-linear multivariate models for estimating global solar radiation received across five cities in South Africa","authors":"T. Govindasamy, N. Chetty","doi":"10.17159/2413-3051/2019/V30I2A6076","DOIUrl":"https://doi.org/10.17159/2413-3051/2019/V30I2A6076","url":null,"abstract":"South Africa continues to lag globally in the adoption of renewable energy systems despite a notable decrease in the cost of applicable renewable energy technologies over the past five years. Most applications of potential solar renewable energy systems are currently in various stages of investigation, leaving this readily accessible resource capacity idle. The present study proposes linear and non-linear analysis of multivariate models for estimating global solar radiation (GSR) received across five cities in South Africa. The significance of this study is to provide effective GSR estimation in the application of solar technologies, while increasing their implementation. The dependency of GSR on meteorological variables such as air temperature, relative humidity and relative sunshine duration was evaluated for January 2007 to June 2018 to realise estimation models for each of the study sites. The Hargreaves-Samani and Angstrom-Prescott empirical models served as the basis for single variable analysis of GSR reliance on each meteorological parameter and their relative variations. The results indicated that the proposed non-linear, multivariate equations perform better than the empirical models as well as linear, single variable regression equations. The suggested models are site-specific and demonstrate a strong correlation to historic GSR values with low, acceptable error indicators. It was also recognised that second- and third-order relationships between the clearness index and multiple meteorological variables provide a more accurate description of GSR for most of the cities under study. These methods are cost-effective, easily accessible and appropriate for the evaluation of the feasibility of solar photovoltaic technologies in South Africa.","PeriodicalId":15666,"journal":{"name":"Journal of Energy in Southern Africa","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85338592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Inferential based statistical indicators for the assessment of solar resource data 基于推理的太阳能资源数据评价统计指标

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2019-03-25 DOI: 10.17159/2413-3051/2019/V30I1A5430

C. Clohessy, G. Sharp, J. Hugo, E. Van Dyk

引用次数: 0

Reactive power and harmonic compensation: A case study for the coal-mining industry 无功功率与谐波补偿:以煤矿工业为例

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2019-03-25 DOI: 10.17159/2413-3051/2019/V30I1A2473

F. Roos, R. Bansal

引用次数: 9

Development of a large-area, low-cost solar water-heating system for South Africa with a high thermal energy collection capacity 为南非开发具有高热能收集能力的大面积低成本太阳能热水系统

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2019-03-22 DOI: 10.17159/2413-3051/2019/V30I1A5226

Monga F. Twite, L. Snyman, J. De Koker, A. Yusuff

{"title":"Development of a large-area, low-cost solar water-heating system for South Africa with a high thermal energy collection capacity","authors":"Monga F. Twite, L. Snyman, J. De Koker, A. Yusuff","doi":"10.17159/2413-3051/2019/V30I1A5226","DOIUrl":"https://doi.org/10.17159/2413-3051/2019/V30I1A5226","url":null,"abstract":"A low-cost heat-exchanger system that can be used in high-pressure/low-pressure isolated solar water-heating systems in South Africa was developed for household applications. The combination of a copper coil and electrical heater allowed for isolation of the high-pressure and low-pressure sections of the system and enabled the utilisation of large low-cost solar heat-absorber platforms that operated at low pressure with a low risk of fouling and leaking. The design comprised a copper coil heat exchanger to be installed inside a conventional geyser, to replace the normal heating element and thermostat system in a conventional commercially available household geyser. The electric heating element still supplements the system in low solar energy conditions. The circulation in the system is created by a small separate photovoltaic panel and a circulation pump. An integrated switch allows the system to alternate between conventional electrical heating and solar water-heating according to prevailing weather conditions. Current tests show that the system of 15 m2 area can be installed at a cost of approximately ZAR 10 000–12 000. The system can provide hot water at approximately 12 cents per kWh, with a total heat storage capacity of up to 10 kWh per day. This implies a saving to the customer of up to ZAR 600 per month. The accumulated saving to a household over the ten-year lifetime of the product is estimated at ZAR 200 000. As the thermal energy storage capacity of current systems as available on the local market is approximately 1 kWhr per day for a 2 m2 collector. A typical increase in thermal energy collection capacity of tenfold more than the capability of conventional systems on the market is hence achieved. The system offers implementation possibilities for South Africa’s low-cost housing schemes and can provide for creating numerous new business and job opportunities on the African continent with its abundant solar irradiation resources.","PeriodicalId":15666,"journal":{"name":"Journal of Energy in Southern Africa","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74068594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

A ray tracer model for analysis of solar concentrating systems 用于分析太阳能聚光系统的射线追踪模型

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2019-03-08 DOI: 10.17159/2413-3051/2019/V30I1A5267

Karidewa Nyeinga, D. Okello, O. Nydal

{"title":"A ray tracer model for analysis of solar concentrating systems","authors":"Karidewa Nyeinga, D. Okello, O. Nydal","doi":"10.17159/2413-3051/2019/V30I1A5267","DOIUrl":"https://doi.org/10.17159/2413-3051/2019/V30I1A5267","url":null,"abstract":"This study describes a 3D ray tracer model for analysis of a small-scale solar concentrating system where thermal heat is collected for cooking purposes. Emitted sun rays were traced from the source through all reflections until they intercepted with the receiver or were lost. The algorithm of the ray tracer and its implementation in MATLAB is clearly described. The ray tracer was programmed to contribute to the development of small-scale concentrating solar energy systems with integrated heat storage units. The ray tracer was demonstrated for selected cases where continuous reflecting surfaces and flat mirror-tiled surfaces were compared. Off-focus sensitivity analysis was shown and this could provide guidelines for the required solar tracking accuracy. The flux distribution on the absorber was analysed and found to be concentrated on a small area on the target for continuous reflecting surfaces and having high intensities. However, for reflectors with mirror tiles, an elongated image was formed centred on the focal point with low intensities. Small misalignment of the reflector in the order 0.2° had minimal impact on the interception ratio, but any further increase in the tracking errors caused a sudden drop in the interception ratio to zero. Results showed that there is close agreement in flux distribution and the tracking error impact on interception ratio, when compared with the literature. This model could be a useful tool when designing the reflection and absorption components of solar concentrators for complex systems with several components in a non-symmetric 3D arrangement.","PeriodicalId":15666,"journal":{"name":"Journal of Energy in Southern Africa","volume":"26 1","pages":"8-20"},"PeriodicalIF":0.0,"publicationDate":"2019-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78950654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Influences of microalgae biomass on the thermal behaviour of waste coal fines 微藻生物量对废煤粉热特性的影响

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2019-03-08 DOI: 10.17159/2413-3051/2019/V30I1A5452

H. Baloyi, Gary M. Dugmore

引用次数: 10

The vulnerability of the South African electricity transmission network infrastructure to weather and climate: A review 南非输电网基础设施对天气和气候的脆弱性:综述

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2018-12-07 DOI: 10.17159/2413-3051/2018/V29I4A4748

M. Majodina, J. Botai, H. Rautenbach

{"title":"The vulnerability of the South African electricity transmission network infrastructure to weather and climate: A review","authors":"M. Majodina, J. Botai, H. Rautenbach","doi":"10.17159/2413-3051/2018/V29I4A4748","DOIUrl":"https://doi.org/10.17159/2413-3051/2018/V29I4A4748","url":null,"abstract":"Meteorological factors have an influence on global energy systems. This study reviewed some of the latest research contributions from other global studies on climate change impacts, energy transportation and international collaboration in the energy-meteorology sector. It is a summary of relevant South African research on energy demand, forecasting and vulnerability to meteorological conditions. International weather-energy partnerships are growing fast, while the Global Framework for Climate Services has provided a global framework for scientific collaboration across sectors to assist with climate-related risk management and decision-making. The uptake in developing regions has remained slow, however, particularly in Africa, where basic requirements such as meteorological observations are still sought. This review found that studies on the impact that future projections of climate change and variability might have on the South African electricity transmission network were inadequate. A deeper understanding of such impacts on the electricity infrastructure would assist considerably with risk management and decision-making; consequently contributing to the sustainable provision of electricity in South Africa.","PeriodicalId":15666,"journal":{"name":"Journal of Energy in Southern Africa","volume":"12 1","pages":"51-59"},"PeriodicalIF":0.0,"publicationDate":"2018-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76446979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

System adequacy in the Southern African Power Pool: A case for capacity mechanisms 南部非洲电力联营的系统充分性:能力机制的案例

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2018-12-07 DOI: 10.17159/2413-3051/2018/V29I4A5581

Jarrad Wright, J. Coller

引用次数: 14

An overview of salient factors, relationships and values to support integrated energy-economic systems dynamic modelling 概述支持综合能源经济系统动态建模的突出因素、关系和价值

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2018-12-03 DOI: 10.17159/2413-3051/2018/V29I4A3417

M. D. Wit, M. Heun, D. Crookes

{"title":"An overview of salient factors, relationships and values to support integrated energy-economic systems dynamic modelling","authors":"M. D. Wit, M. Heun, D. Crookes","doi":"10.17159/2413-3051/2018/V29I4A3417","DOIUrl":"https://doi.org/10.17159/2413-3051/2018/V29I4A3417","url":null,"abstract":"Integrated energy-economic modeling is needed to support the development of energy and carbon policies. We propose that a systems dynamic modeling approach is needed; one that includes (a) dynamics (b) endogenous treatment of uncertainty and risks, and (c) both aggregate economic and disaggregate technical or engineering levels of analysis. To support the future development of integrated energy-economic models we review and organise the literature on energy-economy interactions into subsections covering (a) the key factors or components, (b) the relationships among these components, (c) a quantification of parameters and (d) implications for the development of an integrated energy-economic systems dynamic model. The literature is organized in discussions on economic growth and the factors of production, elasticities, macro- and technical substitutability, energy cost shares, heat engine efficiencies and energy services efficiencies. We observe non-linear relationships in production and consumption, large variations among price and income elasticity values across time frames, across countries and regions, and across energy goods, far from perfect substitution among factors of production and among energy goods on a macro level, technical/engineering limits to substitution on a micro level, as well as engineering and behavioural limits on what can be achieved with increased efficiencies. We therefore support the call to develop integrated energy-economic systems dynamic models that are able to provide new insight into the nature of energy-economic transitions","PeriodicalId":15666,"journal":{"name":"Journal of Energy in Southern Africa","volume":"4 1","pages":"27-36"},"PeriodicalIF":0.0,"publicationDate":"2018-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89843615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Developing a small photovoltaic power supply system with adaptive technologies for rural Africa: Design, cost and efficiency analyses 为非洲农村发展具有适应性技术的小型光伏供电系统:设计、成本和效率分析

4区工程技术

Journal of Energy in Southern Africa Pub Date : 2018-12-03 DOI: 10.17159/2413-3051/2017/V29I4A5399

Steve Mvili-Gampio, L. Snyman

{"title":"Developing a small photovoltaic power supply system with adaptive technologies for rural Africa: Design, cost and efficiency analyses","authors":"Steve Mvili-Gampio, L. Snyman","doi":"10.17159/2413-3051/2017/V29I4A5399","DOIUrl":"https://doi.org/10.17159/2413-3051/2017/V29I4A5399","url":null,"abstract":"The objective of this study was to design a small-scale photovoltaic system to support electricity supply to a rural village in the Republic of Congo. A simple impedance-matching system and an innovative panel-tilting system were implemented as adaptive technologies to increase the power output of the system and reduce its capital and running costs. The experimentally obtained results showed that the daily energy output of a four-panel, 400 W photovoltaic system could be increased by 15% through a series parallel impedance match configuration, and by 36% from 3.3 kWh per day to approximately 4.5 kWh per day through implementing an automated panel tilting system with always normal incidence of solar irradiation on the panels in an equatorial environment. Implementing these technologies accordingly reduced the cost of energy supplied by the same percentages, with an eventual electricity cost of about ZAR 3.60 per kWhr, as calculated over an operation time of ten years, and an initial capital outlay of ZAR 37 per watt. These costs are much lower than for installing power grid lines to the village, and the technology also ensures complete autonomy of power supply to the community. The study also identified the potential to generate many new business and job opportunities locally in this community, as well as in the rest of Africa.","PeriodicalId":15666,"journal":{"name":"Journal of Energy in Southern Africa","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81668582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2