DEVELOPMENT OF COLORLESS DISTRIBUTED COMBUSTION FOR GAS TURBINE APPLICATION

Colorless Distributed Combustion (CDC) is investigated for gas turbine engine application due to its benefit for ultra-low pollutant emission, improved pattern factor, low noise emission, stable combustion and low pressure drop, alleviation of combustion instabilities and increased life of turbine blades with less air cooling requirements. The CDC is characterized by discrete and direct injection of fuel and air at high velocity and the reaction zone is stabilized due to controlled aerodynamics inside the combustor and wider (radially) shear layer mixing. Mixing between the injected air and product gases to form hot and diluted oxidant is required followed by rapid mixing with the fuel. This results in distributed reaction zone instead of a concentrated flame front as observed in conventional diffusion flames and hence, to avoid hot spot regions and provide reduced NOx and CO emissions. The focus of this dissertation is to develop and demonstrate CDC for application to stationary gas turbine combustors which generally operate at thermal intensity of 15MW/m3-atm. However, higher thermal intensity is desirable to reduce hardware costs due to smaller weight and volume of the combustors. Design of high thermal intensity CDC combustor requires careful control of critical parameters, such as, gas recirculation, fuel/oxidizer mixing and residence time characteristics via careful selection of different air and fuel injection configurations to achieve desirable combustion characteristics. This dissertation examines sequential development of low emission colorless distributed combustor operating from thermal intensity of 5MW/m3-atm up to 198MW/m3-atm. Initially, various fuel and air injection configurations were investigated at a low thermal intensity of 5MW/m3-atm. Further investigations were performed for a simpler combustor having single air and fuel injection ports for medium thermal intensity range of 28-57MW/m3-atm. Among the flow configurations investigated, reverse cross-flow configuration was found to give more favorable results possibly due to higher residence time because of reverse flow geometry and faster mixing with the fuel injection in cross-flow. This configuration was investigated in detail by further reducing the combustor volume to give ultra-high thermal intensity of up to 198MW/m3-atm. At thermal intensity of 53MW/m3-atm NO emissions were 4ppm in non-premixed mode and 1ppm in premixed mode and CO emissions were 30ppm in both the modes. The pressure loss was less than 5% and heat loss was less than 15%. The pressure fluctuations were less than 0.025% suggesting very stable combustion. At ultra-high thermal intensity of 170MW/m3-atm NO emissions were 8ppm and 3ppm in non-premixed and premixed modes respectively and CO emissions were about 100ppm in both the modes. Dilution of fuel with nitrogen, carbon dioxide and air resulted in significant reduction in NO emission in non-premixed mode from 8ppm to about 2ppm. Methane was used as fuel for all these investigations. Liquid fuel (ethanol) was also tested and very low NO emission of about 6ppm was obtained in direct injection mode and 2ppm in premixed prevaporized mode. CO emission of about 200ppm was observed in both the modes

An experimental and theoretical investigation of the extent of bypass air within data centres employing aisle containment, and its impact on power consumption

A combination of laboratory experiments and a system model are used to carry out the first investigation into the potential for cold air to bypass IT equipment within data centres (DCs) employing aisle containment, and the effect of this bypass on DC electricity consumption. The laboratory experiments involved applying a differential pressure across commercially available server racks and aisle containment systems and measuring the resulting air flow. The potential to minimise bypass by sealing leakage paths and redesigning racks was investigated and quantified experimentally. A new system model is developed using a combination of manufacturer data, empirical relationships and experimental results to predict the impact of bypass on the power consumption of the various components of a DC's cooling infrastructure. The results show that, at typical cold aisle pressures, as much as 20% of the supplied air may bypass servers by finding alternate paths through the server rack itself. This increases the required flow rate from air conditioning units (ACUs). The system model predicts that: (i) practical measures undertaken to reduce this bypass could reduce total power consumption by up to 8.8% and (ii) excessive pressure differentials across the containment system could also increase power consumption, by up to 16%

The What and How of Teaching Diverse Adult Learners

In this paper, we present an in-progress study to better understand the process by which adult education instructors become more competent teaching diverse adult learners. We provide a brief review of the relevant literature. We then share the findings from the initial survey, which serve as the basis for our current study. The new questions that emerged from the data analysis and the research design of our current study are also described

Changes in Resilience in Students of Occupational Therapy After Their First Exposure to Practice Placement Education

The authors received funding from the European Regional Development Funds (FEDER) (2018/11744).Introduction: Resilience is a multidimensional and dynamic construct associated with positive growth and the capacity to transform stressful and negative factors into opportunities of personal development and self-improvement when faced with difficult experiences. The resilience process of each individual integrates multiple analysis levels, which range from genetic-environmental interactions to a complex process of adaptation between the individual and his/her family, friends, co-workers, society, and culture. Objective: To determine whether resilience improves in students of occupational therapy when exposed for the first time to practice placement education. Methodology: Quasi-experimental, prospective, observational, multi-center study with a sample composed of students from the Degree of Occupational Therapy of the public universities of Malaga (UMA) and Castilla-La Mancha (UCLM) (Spain). Two weeks prior to the beginning of the practice education period, the participants completed a questionnaire that included sociodemographic data and the area of their internships. They were also given the Spanish version of the Connor-Davidson's resilience scale (CD-RISC). All these instruments were also completed 1 week after the end of the clinical practice. Results: There were statistically significant differences between the variables that make up resilience and the different internship areas. On the other hand, there was a significant improvement of global resilience after the clinical practice period, in both women (13.85 points; p < 0.001) and men (7.72 points; p < 0.035), when the internship area was not considered. Conclusions: The results show that resilient students are more optimistic and work to improve a situation beyond doing simply what is expected of them, knowing how to control their feelings. This is beneficial for students in practice education, since, during these, they face difficult situations that require a resilient pattern, which helps reduce stress and the burnout syndrome.European Commission 2018/1174

Exploring Engaging Instructions: Cases of University Professors and Corporate Trainers in the United States

This journal-article-formatted dissertation explores university professors’ and trainers’ practices in engaging students in their classrooms. By systematically examining the current literature related to engaging instruction, I identified the core components of engaging instruction, as well as the strategies to effectively engage students. Despite the paucity of available empirical studies investigating the ‘engagement’ concept for professors and trainers, the available studies were examined to understand how researchers conceptualized and operationalized “effective engagement.” Findings from this literature review provided a theoretical foundation for the research. I explored the perceptions and practices of college professors regarding engaging instruction. I interviewed seven professors face-to-face. Subsequently, I analyzed the interview transcripts using the constant comparative method. Findings from the study showed that the participants had varied views. Nevertheless, they agreed that an engaging professor must focus on learning; consider various aspects of students’ personal development including their cognitive, social, and emotional development; and take care of different student learning styles, for example, visual, auditory, and kinesthetic. Participants expressed the importance of student engagement. Body language, verbal and non-verbal cues, and eye contact were the main parameters used by the participants to evaluate student engagement. Participants also emphasized the importance of asking questions, judging from student responses and assessing instructional effectiveness by evaluating the questions asked by students. Similarly, I also explored seven trainers’ perceptions on engaging instruction and the strategies they used for engaging trainees by conducting face-to-face interviews. I utilized the constant comparison method to analyze the interview transcripts. Major findings indicate that trainers should be trainee-centered in instruction, accommodate different learning styles, elicit trainee participation by creating an encouraging class environment, and connect with trainees by building rapport early in a training session