Browsing by Author "Joseph, Jerusha Sarah."
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Item Study of a solar-assisted air conditioning system for South Africa.(2012) Joseph, Jerusha Sarah.; Inambao, Freddie Liswaniso.In South Africa, a significant amount of electrical energy is used for air conditioning in commercial buildings, on account of the high humidity experienced. Due to its geographical location, the levels of solar irradiation and the demand for air-conditioning of commercial buildings reach maximum levels simultaneously. The South African region daily solar radiation average varies between 4.5 and 6.5 kWh/m2 and when compared to the United States 3.6 kWh/m2 and Europe’s 2.5 kWh/m2 , solar thermal powered cooling technologies has significant potential as this solar irradiation is also available all year around [1]. Utilizing solar energy for an air conditioning system has the advantage that the availability of solar radiation and the need for cooling reach maximum levels simultaneously and proportionally. This type of air conditioning system has an electrical energy saving benefit in light of increasing energy tariffs and the energy crisis currently facing Eskom in South Africa. Solar-assisted Absorption Cooling systems decreases the peak electricity consumption, is less noisy and vibration free, since it does not contain a compressor and this gives a higher reliability, low maintenance and its electricity consumption is approximately four times less (21.8kW versus 5.5kW for 35kW of Cooling) than that of an electric driven chiller containing a mechanical compressor [2]. However, due to the high capital cost of solar powered air-conditioning plants, it is essential that a feasibility analysis be undertaken to indicate and establish a return on capital investment. The main objective of the present study is to investigate and establish the feasibility of a solar-assisted air-conditioning system based on Lithium Bromide and Water (LiBr/H2O) absorption chillers on a medium scale for commercial buildings in terms of energy saving and performance. This study presents the results of the experiment on a solar-assisted air-conditioning facility constructed and installed in October 2009 at Pretoria’s Netcare Moot Hospital. This study has confirmed that a payback period of 13 months can be achieved and the performance parameters of the manufacturer’s specifications for a solar-assisted air conditioning system are exceeded for the South African climate.Item Sustainable energy efficiency and energy security in developing countries: a case study of airports in South Africa.(2022) Joseph, Jerusha Sarah.; Inambao, Freddie Liswaniso.When looking at the penetration of energy efficiency into the built environment and progress in the decrease in reliance on fossil fuel sources for energy generation, there is a definite challenge in obtaining the priority it requires to arrest the exponential increase in carbon emissions. Energy being key to economic development and improvement of the human way of life, developing countries face unique challenges to secure and sustain low carbon energy sources and effectively inculcate energy efficiency. This study aimed to present a solution in the form of an engineering approach entrenched in the three dimensions of business sustainability, i.e., environmental, social, and economic, to ensure that efforts towards energy efficiency and energy security in developing countries are effective and sustained in reducing carbon emissions. This solution was implemented in a live environment for nine airports in South Africa, and the results are presented in the form of case studies. The thesis investigated the global context of the climate change challenge and the global trends regarding carbon emissions from energy generation. The barriers that developing countries face with respect to achieving energy efficiency and energy security are presented together with the focuses required to overcome the barriers. Energy efficiency is investigated from the point of resource extraction to the point of energy end use, investigating energy conversion efficiencies, showing its best-matched end-use, resulting in the determination of principles for energy efficiency from component to system to infrastructure ecosystem. The principles developed were used to write an energy efficiency policy for all new infrastructure adopted at Airport Company South Africa’s (ACSA’s) nine airports in South Africa. An approach to interpreting onsite low carbon energy sources and their generation potential using available commercial technologies is proposed. Principles are created to determine an optimum low carbon energy mix that is suitable to available resources, business focus, operating environment and efficiently matching the site energy demand. The resulting energy mix based on these principles is presented as a case study for ACSA’s airports. The technologies identified for implementation to reduce energy consumption of the airports as well as their carbon footprint through the energy mix are tested for their financial viability using an economic model run via Microsoft Excel. These initiatives are SMART (specific, measurable, achievable, relevant, timed) in that they are specifically chosen for an organisation in a developing country, measurable in economic return and environmental benefit, achievable for the business, relevant to the airports’ geographical location and timed to map a pathway to carbon neutrality in electricity consumption for the airports by 2030. To ensure that the principles defined are sustained through the necessary changes in legislation, personnel and technologies, a set of key factors that underpin energy efficiency and energy security were determined and are presented. A case study of the implementation of these factors for airports in South Africa are presented. The thesis concludes with leveraging the fourth industrial revolution for innovative engineering solutions, presenting smart solutions to close the large development time gaps required for building human capacity, engineering capability and costly storage technologies to mature due to inherent intermittency of renewable energies. The results of the study and its implementation show that the solutions presented for energy efficiency and a low carbon energy mix are realistic and successful, while being grounded in sound scientific and engineering principles and sustained through inevitable changes. This is evident in the various strategies, company policies, technical guidelines and other programmes being approved and implemented by the senior management of the organisation that owns and operates the nine South African airports presented in this case study. The findings of the implementation show that a low carbon energy mix makes business sense, provides energy security and that achieving carbon neutrality is possible through the adoption of carbon offsetting. The “acid test” showing the solution presented in this thesis is being implemented for the nine airports in South Africa is that it still remains as a valid and a business focus even in the financial crisis faced by the aviation industry since the COVID-19 pandemic.