In this thesis, ammonia (NH3) decomposition was assessed as a fuel processing technology for producing on-demand hydrogen (H2) for portable and distributed fuel cell applications. This study was motivated by the present lack of infrastructure to generate H2 for proton exchange membrane (PEM) fuel cells. An overview of past and recent worldwide research activities in the development of reactor technologies for portable and distributed hydrogen generation via NH3 decomposition was presented in Chapter 2. The objective was to uncover the principal challenges relating to the state-of-the-art in reactor technology and obtain a basis for future improvements. Several important aspects such as reactor design, operability, power generation capacity and efficiency (conversion and energy) were appraised for innovative reactor technologies vis-à-vis microreactors, monolithic reactors, membrane reactors, and electrochemical reactors (electrolyzers). It was observed that substantial research effort is required to progress the innovative reactors to commercialization on a wide basis. The use of integrated experimental-mathematical modelling approach (useful in attaining accurately optimized designs) was notably non-existent for all reactors throughout the surveyed openliterature. Microchannel reactors were however identified as a transformative reactor technology for producing on-demand H2 for PEM cell applications. Against this background, miniaturized H2 production in a stand-alone ammonia-fuelled microchannel reactor (reformer) washcoated with a commercial Ni-Pt/Al2O3 catalyst (ActiSorb® O6) was demonstrated successfully in Chapter 3. The reformer performance was evaluated by investigating the effect of reaction temperature (450–700 °C) and gas-hourly-space-velocity (6 520–32 600 Nml gcat -1 h-1) on key performance parameters including NH3 conversion, residual NH3 concentration, H2 production rate, and pressure drop. Particular attention was devoted to defining operating conditions that minimised residual NH3 in reformate gas, while producing H2 at a satisfactory rate. The reformer operated in a daily start-up and shut-down (DSS)-like mode for a total 750 h comprising of 125 cycles, all to mimic frequent intermittent operation envisaged for fuel cell systems. The reformer exhibited remarkable operation demonstrating 98.7% NH3 conversion at 32 600 Nml gcat -1 h-1 and 700 °C to generate an estimated fuel cell power output of 5.7 We and power density of 16 kWe L-1 (based on effective reactor volume). At the same time, reformer operation yielded low pressure drop (<10 Pa mm-1) for all conditions considered. Overall, the microchannel reformer performed sufficiently exceptional to warrant serious consideration in supplying H2 to low-power fuel cell systems. In Chapter 4, hydrogen production from the Ni-Pt-washcoated ammonia-fuelled microchannel reactor was mathematically simulated in a three-dimensional (3D) CFD model implemented via Comsol Multiphysics™. The objective was to obtain an understanding of reaction-coupled transport phenomena as well as a fundamental explanation of the observed microchannel reactor performance. The transport processes and reactor performance were elucidated in terms of velocity, temperature, and species concentration distributions, as well as local reaction rate and NH3 conversion profiles. The baseline case was first investigated to comprehend the behavior of the microchannel reactor, then microstructural design and operating parameters were methodically altered around the baseline conditions to explore the optimum values (case-study optimization). The modelling results revealed that an optimum NH3 space velocity (GHSV) of 65.2 Nl gcat -1 h-1 yields 99.1% NH3 conversion and a power density of 32 kWe L-1 at the highest operating temperature of 973 K. It was also shown that a 40-μm-thick porous washcoat was most desirable at these conditions. Finally, a low channel hydraulic diameter (225 μm) was observed to contribute to high NH3 conversion. Most importantly, mass transport limitations in the porouswashcoat and gas-phase were found to be negligible as depicted by the Damköhler and Fourier numbers, respectively. The experimental microchannel reactor produced 98.2% NH3 conversion and a power density of 30.8 kWe L-1 when tested at the optimum operating conditions established by the model. Good agreement with experimental data was observed, so the integrated experimental-modeling approach used here may well provide an incisive step toward the efficient design of ammonia-fuelled microchannel reformers. In Chapter 5, the prospect of producing H2 via ammonia (NH3) decomposition was evaluated in an experimental stand-alone microchannel reactor wash-coated with a commercial Cs-promoted Ru/Al2O3 catalyst (ACTA Hypermec 10010). The reactor performance was investigated under atmospheric pressure as a function of reaction temperature (723–873 K) and gas-hourly-space-velocity (65.2–326.1 Nl gcat -1 h-1). Ammonia conversion of 99.8% was demonstrated at 326.1 Nl gcat -1 h-1 and 873 K. The H2 produced at this operating condition was sufficient to yield an estimated fuel cell power output of 60 We and power density of 164 kWe L-1. Overall, the Ru-based microchannel reactor outperformed other NH3 microstructured reformers reported in literature including the Ni-based system used in Chapter 3. Furthermore, the microchannel reactor showed a superior performance against a fixed-bed tubular microreactor with the same Ru-based catalyst. Overall, the high H2 throughput exhibited may promote widespread use of the Ru-based micro-reaction system in high-power applications. Four peer-reviewed journal publications and six conference publications resulted from this work. / PhD (Chemical Engineering), North-West University, Potchefstroom Campus, 2015

In this thesis, ammonia (NH3) decomposition was assessed as a fuel processing technology for producing on-demand hydrogen (H2) for portable and distributed fuel cell applications. This study was motivated by the present lack of infrastructure to generate H2 for proton exchange membrane (PEM) fuel cells. An overview of past and recent worldwide research activities in the development of reactor technologies for portable and distributed hydrogen generation via NH3 decomposition was presented in Chapter 2. The objective was to uncover the principal challenges relating to the state-of-the-art in reactor technology and obtain a basis for future improvements. Several important aspects such as reactor design, operability, power generation capacity and efficiency (conversion and energy) were appraised for innovative reactor technologies vis-à-vis microreactors, monolithic reactors, membrane reactors, and electrochemical reactors (electrolyzers). It was observed that substantial research effort is required to progress the innovative reactors to commercialization on a wide basis. The use of integrated experimental-mathematical modelling approach (useful in attaining accurately optimized designs) was notably non-existent for all reactors throughout the surveyed openliterature. Microchannel reactors were however identified as a transformative reactor technology for producing on-demand H2 for PEM cell applications. Against this background, miniaturized H2 production in a stand-alone ammonia-fuelled microchannel reactor (reformer) washcoated with a commercial Ni-Pt/Al2O3 catalyst (ActiSorb® O6) was demonstrated successfully in Chapter 3. The reformer performance was evaluated by investigating the effect of reaction temperature (450–700 °C) and gas-hourly-space-velocity (6 520–32 600 Nml gcat -1 h-1) on key performance parameters including NH3 conversion, residual NH3 concentration, H2 production rate, and pressure drop. Particular attention was devoted to defining operating conditions that minimised residual NH3 in reformate gas, while producing H2 at a satisfactory rate. The reformer operated in a daily start-up and shut-down (DSS)-like mode for a total 750 h comprising of 125 cycles, all to mimic frequent intermittent operation envisaged for fuel cell systems. The reformer exhibited remarkable operation demonstrating 98.7% NH3 conversion at 32 600 Nml gcat -1 h-1 and 700 °C to generate an estimated fuel cell power output of 5.7 We and power density of 16 kWe L-1 (based on effective reactor volume). At the same time, reformer operation yielded low pressure drop (<10 Pa mm-1) for all conditions considered. Overall, the microchannel reformer performed sufficiently exceptional to warrant serious consideration in supplying H2 to low-power fuel cell systems. In Chapter 4, hydrogen production from the Ni-Pt-washcoated ammonia-fuelled microchannel reactor was mathematically simulated in a three-dimensional (3D) CFD model implemented via Comsol Multiphysics™. The objective was to obtain an understanding of reaction-coupled transport phenomena as well as a fundamental explanation of the observed microchannel reactor performance. The transport processes and reactor performance were elucidated in terms of velocity, temperature, and species concentration distributions, as well as local reaction rate and NH3 conversion profiles. The baseline case was first investigated to comprehend the behavior of the microchannel reactor, then microstructural design and operating parameters were methodically altered around the baseline conditions to explore the optimum values (case-study optimization). The modelling results revealed that an optimum NH3 space velocity (GHSV) of 65.2 Nl gcat -1 h-1 yields 99.1% NH3 conversion and a power density of 32 kWe L-1 at the highest operating temperature of 973 K. It was also shown that a 40-μm-thick porous washcoat was most desirable at these conditions. Finally, a low channel hydraulic diameter (225 μm) was observed to contribute to high NH3 conversion. Most importantly, mass transport limitations in the porouswashcoat and gas-phase were found to be negligible as depicted by the Damköhler and Fourier numbers, respectively. The experimental microchannel reactor produced 98.2% NH3 conversion and a power density of 30.8 kWe L-1 when tested at the optimum operating conditions established by the model. Good agreement with experimental data was observed, so the integrated experimental-modeling approach used here may well provide an incisive step toward the efficient design of ammonia-fuelled microchannel reformers. In Chapter 5, the prospect of producing H2 via ammonia (NH3) decomposition was evaluated in an experimental stand-alone microchannel reactor wash-coated with a commercial Cs-promoted Ru/Al2O3 catalyst (ACTA Hypermec 10010). The reactor performance was investigated under atmospheric pressure as a function of reaction temperature (723–873 K) and gas-hourly-space-velocity (65.2–326.1 Nl gcat -1 h-1). Ammonia conversion of 99.8% was demonstrated at 326.1 Nl gcat -1 h-1 and 873 K. The H2 produced at this operating condition was sufficient to yield an estimated fuel cell power output of 60 We and power density of 164 kWe L-1. Overall, the Ru-based microchannel reactor outperformed other NH3 microstructured reformers reported in literature including the Ni-based system used in Chapter 3. Furthermore, the microchannel reactor showed a superior performance against a fixed-bed tubular microreactor with the same Ru-based catalyst. Overall, the high H2 throughput exhibited may promote widespread use of the Ru-based micro-reaction system in high-power applications. Four peer-reviewed journal publications and six conference publications resulted from this work. / PhD (Chemical Engineering), North-West University, Potchefstroom Campus, 2015

As societies across the world are facing grim problems regarding the consumption of tobacco products and alcohol, the Governments of these societies are adapting their strategies to reduce the consumption of these harmful products. These demarketing strategies are implemented to discourage the use of these products and increase the health of consumers. These strategies include a strenuous legal limit when driving under the influence of alcohol, enforcing the placement of warning labels on both cigarette packages as well as alcoholic beverages. Also included are penalties when failing to adhere to these laws, increasing prices, limiting the availability, restricting promotion and advertising, the list goes on. It is therefore seen fit to examine the attitudes of black Generation Y students’ towards the demarketing of smoking and alcohol consumption, because of the research gap concerning black Generation Y students. The primary purpose of this research study was to conclude the attitudes towards the demarketing of smoking and alcohol consumption amongst black Generation Y students within South Africa, and more specifically the Vaal Triangle region. The target population for this study comprised black Generation Y students, aged 18 to 24. A non-probability convenience sample of 200 respondents at each of the two higher education institutions was randomly chosen to participate in this research study making the total sample size 400. A self-administered questionnaire was handed out to each of the respondents to complete. The questionnaire consisted of three sections; Section A – demographical information, Section B – tobacco questionnaire and Section C – alcohol questionnaire. It was required of the respondents to complete the three sections, indicating their agreement or disagreement towards demarketing on a five-point Likert scale. The literature review included in this study comprised marketing as an organisational philosophy and function, market segmentation, targeting and positioning, as well as demarketing. The traditional marketing mix, consumption patterns within South Africa concerning smoking and alcohol, demarketing as a form of social responsibility were also discussed. The term demarketing, the marketing mix in terms of demarketing and the Generation Y cohort were also included within the literature review. The main finding obtained from the main survey questionnaire was that black Generation Y students’ had a positive attitude towards the demarketing of smoking and alcohol consumption. The remaining findings obtained are discussed in order to enhance the understanding of the black Generation Y students’ cohort attitudes. The recommendations for this study are given to guide the successful implementation of demarketing of cigarettes and alcohol. It is concluded from the research, that black Generation Y students’ attitudes towards the demarketing of smoking and alcohol consumption is positive, and that they are in favour of persuading consumers to reduce consumption and ultimately quit the consumption of these products. Therefore, organisations and the Government should continue to implement these demarketing strategies towards smoking and alcohol, especially amongst the black Generation Y students. / Thesis (MCom (Marketing management))--North-West University, Vaal Triangle Campus, 2013

As societies across the world are facing grim problems regarding the consumption of tobacco products and alcohol, the Governments of these societies are adapting their strategies to reduce the consumption of these harmful products. These demarketing strategies are implemented to discourage the use of these products and increase the health of consumers. These strategies include a strenuous legal limit when driving under the influence of alcohol, enforcing the placement of warning labels on both cigarette packages as well as alcoholic beverages. Also included are penalties when failing to adhere to these laws, increasing prices, limiting the availability, restricting promotion and advertising, the list goes on. It is therefore seen fit to examine the attitudes of black Generation Y students’ towards the demarketing of smoking and alcohol consumption, because of the research gap concerning black Generation Y students. The primary purpose of this research study was to conclude the attitudes towards the demarketing of smoking and alcohol consumption amongst black Generation Y students within South Africa, and more specifically the Vaal Triangle region. The target population for this study comprised black Generation Y students, aged 18 to 24. A non-probability convenience sample of 200 respondents at each of the two higher education institutions was randomly chosen to participate in this research study making the total sample size 400. A self-administered questionnaire was handed out to each of the respondents to complete. The questionnaire consisted of three sections; Section A – demographical information, Section B – tobacco questionnaire and Section C – alcohol questionnaire. It was required of the respondents to complete the three sections, indicating their agreement or disagreement towards demarketing on a five-point Likert scale. The literature review included in this study comprised marketing as an organisational philosophy and function, market segmentation, targeting and positioning, as well as demarketing. The traditional marketing mix, consumption patterns within South Africa concerning smoking and alcohol, demarketing as a form of social responsibility were also discussed. The term demarketing, the marketing mix in terms of demarketing and the Generation Y cohort were also included within the literature review. The main finding obtained from the main survey questionnaire was that black Generation Y students’ had a positive attitude towards the demarketing of smoking and alcohol consumption. The remaining findings obtained are discussed in order to enhance the understanding of the black Generation Y students’ cohort attitudes. The recommendations for this study are given to guide the successful implementation of demarketing of cigarettes and alcohol. It is concluded from the research, that black Generation Y students’ attitudes towards the demarketing of smoking and alcohol consumption is positive, and that they are in favour of persuading consumers to reduce consumption and ultimately quit the consumption of these products. Therefore, organisations and the Government should continue to implement these demarketing strategies towards smoking and alcohol, especially amongst the black Generation Y students. / Thesis (MCom (Marketing management))--North-West University, Vaal Triangle Campus, 2013

Computer games have not only invaded the lives of children, but the lives of adults as well. Increasingly, computer games have become a part of popular culture. Initially computer games were considered to be a waste of time, time that could have been better spent doing more worthwhile activities such as studying and physical exercise. Recently, however, attitudes towards computer games have changed; teachers, parents and researchers have started to regard computer games as a possible educational resource. During this new information age it is possible that the children who are part of the Net generation have started to think and process information differently, and that they may have different educational needs. Some researchers think that computer games may serve as an educational tool to support their learning. This literature survey provides an overview of current literature on computer games and education. The review examines the aspects of computer games that support learning, such as motivational factors, social interaction and learning through doing. Further, the review studies the negative aspects that prevent games from being accepted as an educational tool such as the violence portrayed, game addiction, negative stereotyping and asocial behaviour. The Net generation is also examined. The review looks at their characteristics, thinking patterns, skills and their expectations of education. The review then serves as a basis to provide some guidelines for the selection and usage of computer games in the classroom. / Dissertation (MEd (Computer-Integrated Education))--University of Pretoria, 2007. / Science, Mathematics and Technology Education / unrestricted

It has been determined who the adolescent in the Wolmer community is. An investigation into the adolescent’s relationship with the resources in this area was also done. It was determined that this community has a long history of poverty and that a large percentage of the families living here experience a variety of problems. We refer to them as multi-problem families. It has also been confirmed that social services by various organizations have been delivered on an ongoing base over the past eight years. From the literature we have learned that the use of resource’s aid programmes as means of social support, focusing on families, primary and secondary school learners, should have an impact on the future expectations of the children involved. The aim of this study was to determine what the perception of the grade seven learners of their future expectations was. From this it would then be possible to derive what recommendations should be made with regard to social work programmes for the parents and children in the Wolmer community. Socio-economic problems that are not addressed cause bad school performance and as a result of this children tend to leave school at an early age. Leaving school at an early age evidently leads to conflict with the police, imprisonment and alcohol and drug abuse. These aspects tend to be a part of the life in Wolmer and ultimately have an influence on the child attaining his or her goals as well as on his or her future expectations. These will have to be addressed by appropriate school programmes. The researcher’s knowledge of this community leads her to the conclusion that the absence of parenting by the parents of these children, their lack of involvement, lack of skill to equip their children adequately for life, their own lack of adequate knowledge as well as lack of a proper value system tends to play a huge part in the behaviour and perception of the adolescent of their own future expectation. In the Wolmer community children that are sometimes advised by their parents not to leave school at an early age, question this because of parents leaving school at an early age in order to co-provide for their families. In cases where children do not have the cognitive ability to change their surroundings, they tend to too fall back in the vicious circle known to them and the generations before them. The child must be motivated and idealistic and be able to make realistic decisions. Because of this it is of the utmost importance that children that do not have the ability with regard to the abovementioned are assisted in doing so. Also that aid programs in future be focused on this in order to empower the new generation. Parents have a huge influence on the choices made by their children. Regardless of social standing and ability adolescents usually have higher ideals for themselves when their parents motivate them as well as give recognition to good work. The researcher unfortunately came to realize that the assistance by their parents, are a very rare phenomenon in this community. Out of the two focus groups being held with the adolescents, it seemed a lack of interest by the parents, lack of information on higher education as well as little financial resources, have a huge impact and influence on the future expectation of the adolescent in Wolmer. It would be the ideal situation if adolescents chose a career that suited their abilities, interests and personality and that would promote a higher self-esteem. Because of their circumstances this is not always possible for the adolescents in this community. These happen in vary rare cases because the parent’s expectations for their children usually fit their expectations for themselves, which is usually very low. Peer group pressure and peer group acceptance have a huge impact on taking responsibility and on the making of choices. In order to have future success individuals can use their problem-solving abilities, mobilise their social support system and become involved in skills that will promote their social capability. The above mentioned should be actively addressed by social workers in the development of programs that focuses on social support, problem-solving skills, peer group acceptance, school involvement and socio-economic adaptation off adolescents in die Wolmer community. By determining the future expectations of the youth, programs for the empowerment of them can be implemented in order to assist the adolescents to break away from the vicious circle of poverty and to reach their ideals. The researcher is of the opinion that is has become of the utmost importance for the resources in this community, to assess their role presently in the promoting of future expectations and as an outcome of this the promotion of economic-self sustainability. / Dissertation (MSW) (Play Therapy))--University of Pretoria, 2004. / Social Work and Criminology / Unrestricted