An optimum wind power output model for concentrator augmented wind turbines (CAWTs)
- Authors: Shonhiwa, Chipo
- Date: 2017
- Subjects: Wind power Wind turbines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8692 , vital:33427
- Description: The aim of this study was to develop an optimum wind power output model for concentrator augmented wind turbines (CAWTs), which can operate in low wind speed areas. This study was done using computational fluid dynamics modelling (CFD), theoretical and experimental work. Currently the wind resource is contributing 2.5percent of the global electricity supply and is anticipated to increase to by 2050. Despite this, the contribution to wind energy consumption share by South Africa is still low having just exceeded in 2015. Like many other countries, South Africa agrees that climate change is one of the biggest challenges currently being faced by mankind and acknowledges that tackling it requires collaborative effort from all. The Integrated Resource Plan (IRP 2010-2030) passed in 2010 targets 26.3percent renewable energy contribution to national energy consumption by the year 2030 with 10.3percent coming from wind energy hence contributing to abatement of climate change. 1518percent 1 000 MW Small wind turbines are known for their vital contribution to providing electricity in remote areas. Their power output is mainly influenced by the turbine rotor diameter and wind speed which depend on tower height. A cost benefit analysis conducted basing on increasing wind speed by increasing the turbine tower height revealed that for small wind turbines, the optimal height is . Concentrator Augmented Wind Turbines (CAWTs) are one of several concepts that have been suggested to increase the power output per unit rotor cross-sectional area by increasing the wind speed upstream of the turbine. Although some research effort has been put in this area, the major drawback is that the effect of concentrator geometry and environmental conditions on the aerodynamics and hence ultimate performance of CAWTs is still not clear. Also, the CAWTs systems that have been made so far, do not track the wind resulting in CAWT systems receiving wind from one direction thus limiting their performance. 25 m Wind has a very low energy density in nature implying that a bigger rotor area is required to harness kinetic energy for generation of meaningful electrical energy. This has resulted in higher costs of producing energy from wind than conventional sources of energy such as fossil fuels and hydro. To lower the cost of wind energy, researchers have come up with several initiatives to boost wind turbine power output. A brief review of various concepts that have been used in this study included: history of wind turbines, South Africa’s political will to abatement of climate change, wind resource assessment, power output augmentation, estimation of air density, historical development of CAWTs, fundamental parameters influencing the performance of CAWTs, mathematical modelling of wind turbines and dynamic similarity. Some facts were borrowed from these concepts to come up with the current study and explain the observations. With a view to assess any concept, it is necessary to study the fundamental basis from which it originates. Thus, it was vital to develop a fundamental basis of CAWT performance from which solutions to currently prevailing questions on the relationships among the governing parameters were obtained. The momentum theory of bare wind turbines, which is also found in literature was described. A similar approach was then used for developing the theory of CAWT systems. The theories of concentrator losses, density variation with weather conditions and turbulence modelling were also described. It was of utmost significance to evaluate the wind power potential of the Western part of the Eastern Cape Province to assess whether there would be a need for the concentrator augmented wind turbines (CAWTs) in the province and all other regions with similar or lower wind speeds in the country. In this study, five-year-long, hourly average wind speed series between January 2009 and December 2013 for six weather stations in the western part of the Eastern Cape (Bisho, Fort Beaufort, Graaff–Reinet, Grahamstown, Port Elizabeth and Queenstown) were statistically analysed using the Weibull distribution function. The dimensionless Weibull shape parameter varied from 1.7 to 2.2. All the values were low indicating that there is widely dispersed data. This means that the data tend to be distributed uniformly over a relatively wide range wind speed. Therefore, this has a positive implication on wind power generation in all the studied areas because if a suitable turbine is installed, it would get enough wind speed to run for the greater part of the year. The scale parameter varied between 3.5 and 6.3. The values for all the sites except Port Elizabeth were relatively low implying that the days of high wind speeds are few. Therefore, wind turbines that require high wind speeds for operation are not suitable here.
- Full Text:
- Date Issued: 2017
- Authors: Shonhiwa, Chipo
- Date: 2017
- Subjects: Wind power Wind turbines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8692 , vital:33427
- Description: The aim of this study was to develop an optimum wind power output model for concentrator augmented wind turbines (CAWTs), which can operate in low wind speed areas. This study was done using computational fluid dynamics modelling (CFD), theoretical and experimental work. Currently the wind resource is contributing 2.5percent of the global electricity supply and is anticipated to increase to by 2050. Despite this, the contribution to wind energy consumption share by South Africa is still low having just exceeded in 2015. Like many other countries, South Africa agrees that climate change is one of the biggest challenges currently being faced by mankind and acknowledges that tackling it requires collaborative effort from all. The Integrated Resource Plan (IRP 2010-2030) passed in 2010 targets 26.3percent renewable energy contribution to national energy consumption by the year 2030 with 10.3percent coming from wind energy hence contributing to abatement of climate change. 1518percent 1 000 MW Small wind turbines are known for their vital contribution to providing electricity in remote areas. Their power output is mainly influenced by the turbine rotor diameter and wind speed which depend on tower height. A cost benefit analysis conducted basing on increasing wind speed by increasing the turbine tower height revealed that for small wind turbines, the optimal height is . Concentrator Augmented Wind Turbines (CAWTs) are one of several concepts that have been suggested to increase the power output per unit rotor cross-sectional area by increasing the wind speed upstream of the turbine. Although some research effort has been put in this area, the major drawback is that the effect of concentrator geometry and environmental conditions on the aerodynamics and hence ultimate performance of CAWTs is still not clear. Also, the CAWTs systems that have been made so far, do not track the wind resulting in CAWT systems receiving wind from one direction thus limiting their performance. 25 m Wind has a very low energy density in nature implying that a bigger rotor area is required to harness kinetic energy for generation of meaningful electrical energy. This has resulted in higher costs of producing energy from wind than conventional sources of energy such as fossil fuels and hydro. To lower the cost of wind energy, researchers have come up with several initiatives to boost wind turbine power output. A brief review of various concepts that have been used in this study included: history of wind turbines, South Africa’s political will to abatement of climate change, wind resource assessment, power output augmentation, estimation of air density, historical development of CAWTs, fundamental parameters influencing the performance of CAWTs, mathematical modelling of wind turbines and dynamic similarity. Some facts were borrowed from these concepts to come up with the current study and explain the observations. With a view to assess any concept, it is necessary to study the fundamental basis from which it originates. Thus, it was vital to develop a fundamental basis of CAWT performance from which solutions to currently prevailing questions on the relationships among the governing parameters were obtained. The momentum theory of bare wind turbines, which is also found in literature was described. A similar approach was then used for developing the theory of CAWT systems. The theories of concentrator losses, density variation with weather conditions and turbulence modelling were also described. It was of utmost significance to evaluate the wind power potential of the Western part of the Eastern Cape Province to assess whether there would be a need for the concentrator augmented wind turbines (CAWTs) in the province and all other regions with similar or lower wind speeds in the country. In this study, five-year-long, hourly average wind speed series between January 2009 and December 2013 for six weather stations in the western part of the Eastern Cape (Bisho, Fort Beaufort, Graaff–Reinet, Grahamstown, Port Elizabeth and Queenstown) were statistically analysed using the Weibull distribution function. The dimensionless Weibull shape parameter varied from 1.7 to 2.2. All the values were low indicating that there is widely dispersed data. This means that the data tend to be distributed uniformly over a relatively wide range wind speed. Therefore, this has a positive implication on wind power generation in all the studied areas because if a suitable turbine is installed, it would get enough wind speed to run for the greater part of the year. The scale parameter varied between 3.5 and 6.3. The values for all the sites except Port Elizabeth were relatively low implying that the days of high wind speeds are few. Therefore, wind turbines that require high wind speeds for operation are not suitable here.
- Full Text:
- Date Issued: 2017
Effects of substance abuse among the youth : the case of Dimbaza Township, King Williams Town Eastern Cape
- Authors: Manyonta, Ayanda
- Date: 2017
- Subjects: Youth -- Substance use -- South Africa -- Eastern Cape Substance abuse -- South Africa -- Eastern Cape Youth -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/9389 , vital:34338
- Description: Youth substance abuse is a major social and health concern globally, South Africa notwithstanding. The effect of using substances among the youth does not only impend overall personal development of the youth, but it also limits their aspiration for the future and creates an environment that exacerbates to social ills. This study explored the effects of substance abuse among the youth in Dimbaza King Williams Town. The study intended to achieve the following specific objectives: (i) to establish the extent of the effects of substance abuse among the youth in Dimbaza township; (ii) determine the impact of the effects of substance abuse towards the development of Dimbaza Township; (iii) document interventional strategies to mitigate the effects of substance abuse. The study used a qualitative approach, where explorative and descriptive designs were used. Specifically, the case study design was used. Data was collected through in-depth interviews, focus groups, secondary data and key informants methods. The study used non-probability sampling techniques, but specifically purpose sampling technique was used. Twenty eight (28) participants were sampled which comprised of (12) youth faced with substance related challenges, (6) family members, and (10) key informants. Data was analyzed qualitatively through content thematic analysis. The study revealed the following: preponderance of marijuana (dagga) and alcohol, peer pressure as precursor to substance abuse, antisocial behaviours attributable to substance abuse, youth engagement in various criminal activities, evidence of moral decay in Dimbaza, state of poverty aggravating substance abuse habits, paucity of community intervention for social ills. The study made the following recommendations: a need for government to intensify awareness of the impact of substance abuse among the youth; the need for social practitioners to mitigate dysfunctional families facing substance related challenges; strategic educational intervention targeting potential addicts are needed so as to curb the proliferation the effect of substance abuse; establishment of family educational programs are needed to capacitate communities in order to mitigating substance related behaviors;; special police force is needed to strengthen substance abuse campaigns as primary intervention so as to educate pre-adolescents about the aftermaths of substance abuse; moral regeneration initiatives are needed to instill the significance of Ubuntu and worth of human being; intensify of moral regeneration campaigns facilitated by faith-based organizations; and lastly, the government and other stakeholders should fund youth development programs that will equip them with skills to afford them opportunities to bolster their lives and contribute to improving their country’s economy.
- Full Text:
- Date Issued: 2017
- Authors: Manyonta, Ayanda
- Date: 2017
- Subjects: Youth -- Substance use -- South Africa -- Eastern Cape Substance abuse -- South Africa -- Eastern Cape Youth -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/9389 , vital:34338
- Description: Youth substance abuse is a major social and health concern globally, South Africa notwithstanding. The effect of using substances among the youth does not only impend overall personal development of the youth, but it also limits their aspiration for the future and creates an environment that exacerbates to social ills. This study explored the effects of substance abuse among the youth in Dimbaza King Williams Town. The study intended to achieve the following specific objectives: (i) to establish the extent of the effects of substance abuse among the youth in Dimbaza township; (ii) determine the impact of the effects of substance abuse towards the development of Dimbaza Township; (iii) document interventional strategies to mitigate the effects of substance abuse. The study used a qualitative approach, where explorative and descriptive designs were used. Specifically, the case study design was used. Data was collected through in-depth interviews, focus groups, secondary data and key informants methods. The study used non-probability sampling techniques, but specifically purpose sampling technique was used. Twenty eight (28) participants were sampled which comprised of (12) youth faced with substance related challenges, (6) family members, and (10) key informants. Data was analyzed qualitatively through content thematic analysis. The study revealed the following: preponderance of marijuana (dagga) and alcohol, peer pressure as precursor to substance abuse, antisocial behaviours attributable to substance abuse, youth engagement in various criminal activities, evidence of moral decay in Dimbaza, state of poverty aggravating substance abuse habits, paucity of community intervention for social ills. The study made the following recommendations: a need for government to intensify awareness of the impact of substance abuse among the youth; the need for social practitioners to mitigate dysfunctional families facing substance related challenges; strategic educational intervention targeting potential addicts are needed so as to curb the proliferation the effect of substance abuse; establishment of family educational programs are needed to capacitate communities in order to mitigating substance related behaviors;; special police force is needed to strengthen substance abuse campaigns as primary intervention so as to educate pre-adolescents about the aftermaths of substance abuse; moral regeneration initiatives are needed to instill the significance of Ubuntu and worth of human being; intensify of moral regeneration campaigns facilitated by faith-based organizations; and lastly, the government and other stakeholders should fund youth development programs that will equip them with skills to afford them opportunities to bolster their lives and contribute to improving their country’s economy.
- Full Text:
- Date Issued: 2017
Perceptions of school stakeholders towards the use of English as a language of learning and teaching (LoLT) in grade 9 Social Sciences
- Authors: Soya, Nongesiba
- Date: 2017
- Subjects: English language -- Study and teaching English language -- Usage
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10353/6447 , vital:29720
- Description: The dawn of democracy in South Africa led to the development of Language in Education Policy (LiEP) as one of the pieces of legislations that promote languages in schools where parents, learners, who have come of age may choose a language for instruction. LiEP, together with the Constitution of South Africa, promote equal value of all eleven official languages spoken in this country. The promotion of language policies clearly shows that language is the bedrock of the academic development of every child. Unfortunately, Spaull, Van der Berg, Wills, Gustafsson and Kotzè (2016) found that South African Foundation Phase learners lack the most basic skill needed for academic achievement, reading for meaning. Spaull et.al (2016) findings show that language problems start during the early years of schooling. This study aimed at finding out the perceptions of school stakeholders about the use of English as LoLT in Grade 9 Social Sciences, and it is located in the Interpretivist Paradigm. In this study, stakeholders are learners because they are central to learning, parents, as they have the responsibility of choosing LoLT for their children and assist them in their schooling career. Lastly, teachers are stakeholders because of their critical role of imparting knowledge and skills during classroom interaction. The researcher uses a Qualitative approach to identify data-collecting tools suitable for this research, and chooses semi-structured interviews and observations. Semi-structured interviews are flexible and allow deeper probing during the interview. The sample consists of nine Grade 9 learners, three teachers of Grade 9 Social Sciences and six parents from the School Governing Body (SGB). The aim of conducting observations was to find out the language used by learners and teachers during classroom interaction. This study found out that most participants prefer learning Social Sciences in English than in isiXhosa. They are aware of the challenges experienced in the classroom when learning in English but they still choose it. From the sample used, participants clearly indicate that learning in English causes some barriers in the learning and teaching process. However, it also became clear that the benefits associated with learning in English make it difficult to put it at the same level as other languages and participants do not link mother tongue to career opportunities. It is also evident that English will enjoy its hegemony until such time that all stakeholders in Education view the mother tongue as a foundation for learning other languages and as a resource as well so that they can use it in the classroom to understand the content. Policy developers must look deeply into the question of LoLT so that learners receive instruction in a language that will assist them in improved academic performance. Teachers must be equipped with adequate skills to assist learners in developing reading and comprehension skills in the classroom. There is a dire need to develop the culture of reading in rural school learners; and teachers must expose learners to a variety of English reading material.
- Full Text:
- Date Issued: 2017
- Authors: Soya, Nongesiba
- Date: 2017
- Subjects: English language -- Study and teaching English language -- Usage
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10353/6447 , vital:29720
- Description: The dawn of democracy in South Africa led to the development of Language in Education Policy (LiEP) as one of the pieces of legislations that promote languages in schools where parents, learners, who have come of age may choose a language for instruction. LiEP, together with the Constitution of South Africa, promote equal value of all eleven official languages spoken in this country. The promotion of language policies clearly shows that language is the bedrock of the academic development of every child. Unfortunately, Spaull, Van der Berg, Wills, Gustafsson and Kotzè (2016) found that South African Foundation Phase learners lack the most basic skill needed for academic achievement, reading for meaning. Spaull et.al (2016) findings show that language problems start during the early years of schooling. This study aimed at finding out the perceptions of school stakeholders about the use of English as LoLT in Grade 9 Social Sciences, and it is located in the Interpretivist Paradigm. In this study, stakeholders are learners because they are central to learning, parents, as they have the responsibility of choosing LoLT for their children and assist them in their schooling career. Lastly, teachers are stakeholders because of their critical role of imparting knowledge and skills during classroom interaction. The researcher uses a Qualitative approach to identify data-collecting tools suitable for this research, and chooses semi-structured interviews and observations. Semi-structured interviews are flexible and allow deeper probing during the interview. The sample consists of nine Grade 9 learners, three teachers of Grade 9 Social Sciences and six parents from the School Governing Body (SGB). The aim of conducting observations was to find out the language used by learners and teachers during classroom interaction. This study found out that most participants prefer learning Social Sciences in English than in isiXhosa. They are aware of the challenges experienced in the classroom when learning in English but they still choose it. From the sample used, participants clearly indicate that learning in English causes some barriers in the learning and teaching process. However, it also became clear that the benefits associated with learning in English make it difficult to put it at the same level as other languages and participants do not link mother tongue to career opportunities. It is also evident that English will enjoy its hegemony until such time that all stakeholders in Education view the mother tongue as a foundation for learning other languages and as a resource as well so that they can use it in the classroom to understand the content. Policy developers must look deeply into the question of LoLT so that learners receive instruction in a language that will assist them in improved academic performance. Teachers must be equipped with adequate skills to assist learners in developing reading and comprehension skills in the classroom. There is a dire need to develop the culture of reading in rural school learners; and teachers must expose learners to a variety of English reading material.
- Full Text:
- Date Issued: 2017
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