Matching Items (158)
Description
A novel concept for integration of flame-assisted fuel cells (FFC) with a gas turbine is analyzed in this paper. Six different fuels (CH4, C3H8, JP-4, JP-5, JP-10(L), and H2) are investigated for the analytical model of the FFC integrated gas turbine hybrid system. As equivalence ratio increases, the efficiency of the hybrid system increases initially then decreases because the decreasing flow rate of air begins to outweigh the increasing hydrogen concentration. This occurs at an equivalence ratio of 2 for CH4. The thermodynamic cycle is analyzed using a temperature entropy diagram and a pressure volume diagram. These thermodynamic diagrams show as equivalence ratio increases, the power generated by the turbine in the hybrid setup decreases. Thermodynamic analysis was performed to verify that energy is conserved and the total chemical energy going into the system was equal to the heat rejected by the system plus the power generated by the system. Of the six fuels, the hybrid system performs best with H2 as the fuel. The electrical efficiency with H2 is predicted to be 27%, CH4 is 24%, C3H8 is 22%, JP-4 is 21%, JP-5 is 20%, and JP-10(L) is 20%. When H2 fuel is used, the overall integrated system is predicted to be 24.5% more efficient than the standard gas turbine system. The integrated system is predicted to be 23.0% more efficient with CH4, 21.9% more efficient with C3H8, 22.7% more efficient with JP-4, 21.3% more efficient with JP-5, and 20.8% more efficient with JP-10(L). The sensitivity of the model is investigated using various fuel utilizations. When CH4 fuel is used, the integrated system is predicted to be 22.7% more efficient with a fuel utilization efficiency of 90% compared to that of 30%.
ContributorsRupiper, Lauren Nicole (Author) / Milcarek, Ryan (Thesis director) / Wang, Liping (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School for Engineering of Matter,Transport & Enrgy (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Purpose: To examine: (1) whether Non-Hispanic Blacks (NHB) and Non-Hispanic Whites (NHW) with diagnosed arthritis differed in self-reported physical activity (PA) levels, (2) if NHB and NHW with arthritis differed on potential correlates of PA based on the Social Ecological Model (Mcleroy et al., 1988), and (3) if PA participation varied by race/ethnicity after controlling for age, gender, education, and BMI. Methods: This study was a secondary data analysis of data collected from 2006-2008 in Chicago, IL as part of the Midwest Roybal Center for Health Promotion. Bivariate analyses were used to assess potential differences between race in meeting either ACR or ACSM PA guidelines. Comparisons by race between potential socio-demographic correlates and meeting physical activity guidelines were assessed using Chi-squares. Potential differences by race in psychosocial, arthritis, and health-related and environmental correlates were assessed using T-tests. Finally, logistic regression analyses were used to examine if race was still associated with PA after controlling for socio-demographic characteristics. Results: A greater proportion of NHW (68.1% and 35.3%) than NHB (46.5% and 20.9%) met both the arthritis-specific and the American College of Sports Medicine (ACSM) recommendations for physical activity, respectively. NHB had significantly lower self-efficacy for exercise and reported greater impairments in physical function compared to NHW. Likewise, NHB reported more crime and less aesthetics within their neighborhood. NHW were 2.56 times more likely to meet arthritis-specific PA guidelines than NHB after controlling for age, gender, education, marital status, and BMI. In contrast, after controlling for sociodemographic characteristics, age and gender were the only significant predictors of meeting ACSM PA guidelines. Discussion: There were significant differences between NHB and NHW individuals with arthritis in meeting PA guidelines. After controlling for age, gender, education, and BMI non-Hispanic White individuals were still significantly more likely to meet PA guidelines. Interventions aimed at promoting higher levels of physical activity among individuals with arthritis need to consider neighborhood aesthetics and crime when designing programs. More arthritis-specific programs are needed in close proximity to neighborhoods in an effort to promote physical activity.
ContributorsChuran, Christopher (Author) / Der Ananian, Cheryl (Thesis advisor) / Adams, Marc (Committee member) / Campbell, Kathryn (Committee member) / Arizona State University (Publisher)
Created2013
Description
Production from a high pressure gas well at a high production-rate encounters the risk of operating near the choking condition for a compressible flow in porous media. The unbounded gas pressure gradient near the point of choking, which is located near the wellbore, generates an effective tensile stress on the porous rock frame. This tensile stress almost always exceeds the tensile strength of the rock and it causes a tensile failure of the rock, leading to wellbore instability. In a porous rock, not all pores are choked at the same flow rate, and when just one pore is choked, the flow through the entire porous medium should be considered choked as the gas pressure gradient at the point of choking becomes singular. This thesis investigates the choking condition for compressible gas flow in a single microscopic pore. Quasi-one-dimensional analysis and axisymmetric numerical simulations of compressible gas flow in a pore scale varicose tube with a number of bumps are carried out, and the local Mach number and pressure along the tube are computed for the flow near choking condition. The effects of tube length, inlet-to-outlet pressure ratio, the number of bumps and the amplitude of the bumps on the choking condition are obtained. These critical values provide guidance for avoiding the choking condition in practice.
ContributorsYuan, Jing (Author) / Chen, Kangping (Thesis advisor) / Wang, Liping (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2013
Description
Tesla turbo-machinery offers a robust, easily manufactured, extremely versatile prime mover with inherent capabilities making it perhaps the best, if not the only, solution for certain niche applications. The goal of this thesis is not to optimize the performance of the Tesla turbine, but to compare its performance with various working fluids. Theoretical and experimental analyses of a turbine-generator assembly utilizing compressed air, saturated steam and water as the working fluids were performed and are presented in this work. A brief background and explanation of the technology is provided along with potential applications. A theoretical thermodynamic analysis is outlined, resulting in turbine and rotor efficiencies, power outputs and Reynolds numbers calculated for the turbine for various combinations of working fluids and inlet nozzles. The results indicate the turbine is capable of achieving a turbine efficiency of 31.17 ± 3.61% and an estimated rotor efficiency 95 ± 9.32%. These efficiencies are promising considering the numerous losses still present in the current design. Calculation of the Reynolds number provided some capability to determine the flow behavior and how that behavior impacts the performance and efficiency of the Tesla turbine. It was determined that turbulence in the flow is essential to achieving high power outputs and high efficiency. Although the efficiency, after peaking, begins to slightly taper off as the flow becomes increasingly turbulent, the power output maintains a steady linear increase.
ContributorsPeshlakai, Aaron (Author) / Phelan, Patrick (Thesis advisor) / Trimble, Steve (Committee member) / Wang, Liping (Committee member) / Arizona State University (Publisher)
Created2012
Description
This work summarizes the development of a dynamic measurement platform in a cryostat to measure sample temperature response to space-like conditions and the creation a MATLAB theoretical model to predict sample temperature responses in the platform itself. An interesting variable-emittance sample called a Fabry-Perot emitter was studied for its thermal homeostasis behavior using the two developments. Using the measurement platform, it was shown that there was no thermal homeostatic behavior demonstrated by the sample at steady state temperatures. Theoretical calculations show other ways to demonstrate the cooling homeostasis behavior through time-varying heat inputs. Factors within the system such as heat loss and thermal mass contributed to an inhibited sample performance in the platform. Future work will have to be conducted, not only to verify the findings of the initial experiments but also to improve the measurement platform and the theoretical model.
ContributorsBoman, Neal D (Author) / Wang, Liping (Thesis director) / Taylor, Syndey (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
A thermochromic mid-infrared filter is designed, where a spectrally-selective transmittance peak exists while vanadium dioxide layers are below their transition temperature but broad opaqueness is observed below the transition temperature. This filter takes advantage of interference effects between a silicon spacer and insulating vanadium dioxide to create the transmittance peak and the drastic optical property change between insulating and metallic vanadium dioxide. The theoretical performance of the filter in energy dissipation and thermal camouflaging applications is analyzed and can be optimized by tuning the thicknesses of the thin-film layers.
ContributorsChao, Jeremy (Author) / Wang, Liping (Thesis director) / Taylor, Sydney (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
With an excessive amount of resources in the United States healthcare system being spent on the treatment of diseases that are largely preventable through lifestyle change, the need for successful physical activity interventions is apparent. Unfortunately an individual's physical activity and health goals are often not supported by the social context of their daily lives. This single-case design study, Walking Intervention through Text messaging for CoHabiting individuals (WalkIT CoHab), looks at the efficacy of a text based adaptive physical activity intervention to promote walking over a three month period and the effects of social support in intervention performance in three pairs of cohabiting pairs of individuals (n=6). Mean step increase from baseline to intervention ranged from 1300 to 3000 steps per day for all individuals, an average 45.87% increase in physical activity. Goal attainment during the intervention ranged from 43.96% to 71.43%, meaning all participants exceeded the 40% success rate predicted by 60th percentile goals. Social support scores for study partners, unlike social support scores for family and friends, were often in the high social support range and had a moderate increase from pre to post visits for most participants. Although there was variation amongst participants, there was a high correlation in physical activity trends and successful goal attainment in each pair of participants. Less ambitious percentile goals and more personalized motivational text messages might be beneficial to some participants. An extended intervention, something the majority of participants expressed interest in, would further support the efficacy of this behavioral intervention and allow for possible long term benefits of social support in the intervention to be investigated.
ContributorsFernandez, Jacqueline Alyssa (Author) / Adams, Marc (Thesis director) / Angadi, Siddhartha (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Zeolitic Imidazolate Frameworks (ZIFs) are a promising technology for the separation of gases. ZIFs represent a type of hybrid material that is a subset of metal organic frameworks while displaying zeolite properties. ZIFs have tunable pore metrics, high thermal stability, and large surface areas giving them advantages over traditional zeolites. The experiment sought to determine the flux of hexane vapor through ZIF-68 with Fourier Transform Infrared Spectroscopy (FTIR) mapping. FTIR mapping was used to obtain three spectra per crystal and the concentration gradient was analyzed to determine the flux. ZIF-68 was completely stable when loaded with hexane and exposed to the atmosphere. There was no hexane diffusion out of the crystal. As a result, ZIF-68 was heated to 50°C to increase diffusion and calculate the flux. ZIF-68 adhered to Knudsen Diffusion, and the flux was calculated to be 2.00*10-5 kg mol/s*m2. The small flux occurred because almost no concentration gradient was obtained through the crystal. It was hypothesized that the resistance in the crystal was substantially lower than the resistance at the boundary layer, which would have caused a small concentration gradient. Using film mass transfer theory, the resistance inside the crystal was found to be 1200 times lower than the resistance at the boundary layer confirming the hypothesis.
ContributorsSigrist, Dallas Dale (Author) / Lin, Jerry (Thesis director) / Wang, Liping (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
An increasingly sedentary population in the United States, specifically with adolescents, is putting youth at risk of future health related trauma and disease. This single-case design study, Walking Intervention Through Text Messaging for Adolescents (WalkIT-A), was used to intervene with a 12-year old, physically inactive male, in an attempt to test the efficacy of a 12-week physical activity program that may help reduce health risks by increasing number of steps walked per day. The components of the intervention consisted of a FitBit Zip pedometer, physical activity education, text messages, monetary incentives, and goal setting that adapted personally to the participant. Mean step count increased by 30% from baseline (mean = 3603 [sd = 1983]) to intervention (mean = 4693 [sd = 2112]); then increased slightly by 6.7% from intervention to withdrawal (mean = 5009 [sd = 2152]). Mean "very active minutes" increased by 45% from baseline (mean = 8.8 [sd = 8.9]) to intervention (mean = 12.8 [sd = 9.6]); then increased by 61.7% from intervention to withdrawal (mean = 20.7 [sd = 8.4]). Weight, BMI, and blood pressure all increased modestly from pre to post. Cardiovascular fitness (estimated VO2 max) improved by 12.5% from pre (25.5ml*kg-1*min-1) to post (28.7ml*kg-1*min-1). The intervention appeared to have a delayed and residual effect on the participant's daily steps and very active minutes. Although the idealistic ABA pattern did not occur, and the participant did not meet the target of 11,500 daily steps, a positive trend toward that target behavior in the latter 1/3rd of the intervention was observed. Results suggest the need for an extended intervention over a longer period of time and customized even further to the participant.
ContributorsLamb, Nicholas Reid (Author) / Adams, Marc (Thesis director) / Ainsworth, Barbara (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2014-12
Description
The WalkIT Study is a mobile health study examining the efficacy of a four month text message-based intervention for increasing physical activity among 96 overweight adults. The purpose of this thesis is to examine the potency of the different types of motivational prompt-to-action text messages used in the WalkIT Study for increasing steps per day by examining the individual messages, creating qualitative themes and comparing themed groups, and evaluating the interaction between demographic subgroups and themed groups. A total of nine themes was created. The results found that Message 13, “It doesn't matter how old you are – it's never too early or too late to become physically active so start today; only then will you start to see results!”, had the highest median step count (7129 steps) and Message 71, “It's ok if you can't reach your goal today. Just push yourself more tomorrow.”, had the lowest median step count (5054 steps). For themes, the highest median step count (6640 steps) was found in Theme 6, Challenges, and the lowest median step count (5450 steps) was found in Theme 9, Unconditional Feedback. Theme 6 (Challenges) had the highest median step count for females, Theme 7 (Everyday Tips) had the highest median step count for males, Theme 4 (Nutrition) had the highest median step count for the 18-42 group, Theme 6 (Challenges) had the highest median step count for the 43-61 group, and Theme 9 (Unconditional Feedback) had the lowest median step count for both genders and both age groups. The results suggest the usefulness of analyzing the effectiveness of individual motivational text messages, themes, and the interaction between demographic groups and themes in physical activity interventions.
ContributorsBhuiyan, Nishat Anjum (Author) / Adams, Marc (Thesis director) / Ainsworth, Barbara (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2015-05