Matching Items (30)
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- All Subjects: engineering
- Creators: Phelan, Patrick
Description
In this thesis the performance of a Hybrid AC System (HACS) is modeled and optimized. The HACS utilizes solar photovoltaic (PV) panels to help reduce the demand from the utility during peak hours. The system also includes an ice Thermal Energy Storage (TES) tank to accumulate cooling energy during off-peak hours. The AC runs continuously on grid power during off-peak hours to generate cooling for the house and to store thermal energy in the TES. During peak hours, the AC runs on the power supplied from the PV, and cools the house along with the energy stored in the TES. A higher initial cost is expected due to the additional components of the HACS (PV and TES), but a lower operational cost due to higher energy efficiency, energy storage and renewable energy utilization. A house cooled by the HACS will require a smaller size AC unit (about 48% less in the rated capacity), compared to a conventional AC system. To compare the cost effectiveness of the HACS with a regular AC system, time-of-use (TOU) utility rates are considered, as well as the cost of the system components and the annual maintenance. The model shows that the HACS pays back its initial cost of $28k in about 6 years with an 8% APR, and saves about $45k in total cost when compared to a regular AC system that cools the same house for the same period of 6 years.
ContributorsJubran, Sadiq (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Trimble, Steve (Committee member) / Arizona State University (Publisher)
Created2011
Description
As the demand for power increases in populated areas, so will the demand for water. Current power plant technology relies heavily on the Rankine cycle in coal, nuclear and solar thermal power systems which ultimately use condensers to cool the steam in the system. In dry climates, the amount of water to cool off the condenser can be extremely large. Current wet cooling technologies such as cooling towers lose water from evaporation. One alternative to prevent this would be to implement a radiative cooling system. More specifically, a system that utilizes the volumetric radiation emission from water to the night sky could be implemented. This thesis analyzes the validity of a radiative cooling system that uses direct radiant emission to cool water. A brief study on potential infrared transparent cover materials such as polyethylene (PE) and polyvinyl carbonate (PVC) was performed. Also, two different experiments to determine the cooling power from radiation were developed and run. The results showed a minimum cooling power of 33.7 W/m2 for a vacuum insulated glass system and 37.57 W/m2 for a tray system with a maximum of 98.61 Wm-2 at a point when conduction and convection heat fluxes were considered to be zero. The results also showed that PE proved to be the best cover material. The minimum numerical results compared well with other studies performed in the field using similar techniques and materials. The results show that a radiative cooling system for a power plant could be feasible given that the cover material selection is narrowed down, an ample amount of land is available and an economic analysis is performed proving it to be cost competitive with conventional systems.
ContributorsOvermann, William (Author) / Phelan, Patrick (Thesis advisor) / Trimble, Steve (Committee member) / Taylor, Robert (Committee member) / Arizona State University (Publisher)
Created2011
Description
Self-efficacy in engineering, engineering identity, and coping in engineering have been shown in previous studies to be highly important in the advancement of one’s development in the field of engineering. Through the creation and deployment of a 17 question survey, undergraduate and first year masters students were asked to provide information on their engagement at their university, their demographic information, and to rank their level of agreement with 22 statements relating to the aforementioned ideas. Using the results from the collected data, exploratory factor analysis was completed to identify the factors that existed and any correlations. No statistically significant correlations between the identified three factors and demographic or engagement information were found. There needs to be a significant increase in the data sample size for statistically significant results to be found. Additionally, there is future work needed in the creation of an engagement measure that successfully reflects the level and impact of participation in engineering activities beyond traditional coursework.
ContributorsJones, Elizabeth Michelle (Author) / Ganesh, Tirupalavanam (Thesis director) / Graham, Kaely (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
The ability to shift the photovoltaic (PV) power curve and make the energy accessible during peak hours can be accomplished through pairing solar PV with energy storage technologies. A prototype hybrid air conditioning system (HACS), built under supervision of project head Patrick Phelan, consists of PV modules running a DC compressor that operates a conventional HVAC system paired with a second evaporator submerged within a thermal storage tank. The thermal storage is a 0.284m3 or 75 gallon freezer filled with Cryogel balls, submerged in a weak glycol solution. It is paired with its own separate air handler, circulating the glycol solution. The refrigerant flow is controlled by solenoid valves that are electrically connected to a high and low temperature thermostat. During daylight hours, the PV modules run the DC compressor. The refrigerant flow is directed to the conventional HVAC air handler when cooling is needed. Once the desired room temperature is met, refrigerant flow is diverted to the thermal storage, storing excess PV power. During peak energy demand hours, the system uses only small amounts of grid power to pump the glycol solution through the air handler (note the compressor is off), allowing for money and energy savings. The conventional HVAC unit can be scaled down, since during times of large cooling demands the glycol air handler can be operated in parallel with the conventional HVAC unit. Four major test scenarios were drawn up in order to fully comprehend the performance characteristics of the HACS. Upon initial running of the system, ice was produced and the thermal storage was charged. A simple test run consisting of discharging the thermal storage, initially ~¼ frozen, was performed. The glycol air handler ran for 6 hours and the initial cooling power was 4.5 kW. This initial test was significant, since greater than 3.5 kW of cooling power was produced for 3 hours, thus demonstrating the concept of energy storage and recovery.
ContributorsPeyton-Levine, Tobin (Author) / Phelan, Patrick (Thesis advisor) / Trimble, Steve (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2012
Description
This study analyzes the thermoelectric phenomena of nanoparticle suspensions, which are composed of liquid and solid nanoparticles that show a relatively stable Seebeck coefficient as bulk solids near room temperature. The approach is to explore the thermoelectric character of the nanoparticle suspensions, predict the outcome of the experiment and compare the experimental data with anticipated results. In the experiment, the nanoparticle suspension is contained in a 15cm*2.5cm*2.5cm glass container, the temperature gradient ranges from 20 °C to 60 °C, and room temperature fluctuates from 20 °C to 23°C. The measured nanoparticles include multiwall carbon nanotubes, aluminum dioxide and bismuth telluride. A temperature gradient from 20 °C to 60 °C is imposed along the length of the container, and the resulting voltage (if any) is measured. Both heating and cooling processes are measured. With three different nanoparticle suspensions (carbon nano tubes, Al2O3 nanoparticles and Bi2Te3 nanoparticles), the correlation between temperature gradient and voltage is correspondingly 8%, 38% and 96%. A comparison of results calculated from the bulk Seebeck coefficients with our measured results indicate that the Seebeck coefficient measured for each suspension is much more than anticipated, which indicates that the thermophoresis effect could have enhanced the voltage. Further research with a closed-loop system might be able to affirm the results of this study.
ContributorsZhu, Moxuan (Author) / Phelan, Patrick (Thesis advisor) / Trimble, Steve (Committee member) / Prasher, Ravi (Committee member) / Arizona State University (Publisher)
Created2010
Description
Phase Change Material (PCM) plays an important role as a thermal energy storage device by utilizing its high storage density and latent heat property. One of the potential applications for PCM is in buildings by incorporating them in the envelope for energy conservation. During the summer season, the benefits are a decrease in overall energy consumption by the air conditioning unit and a time shift in peak load during the day. Experimental work was carried out by Arizona Public Service (APS) in collaboration with Phase Change Energy Solutions (PCES) Inc. with a new class of organic-based PCM. This "BioPCM" has non-flammable properties and can be safely used in buildings. The experimental setup showed maximum energy savings of about 30%, a maximum peak load shift of ~ 60 min, and maximum cost savings of about 30%. Simulation was performed to validate the experimental results. EnergyPlus was chosen as it has the capability to simulate phase change material in the building envelope. The building material properties were chosen from the ASHRAE Handbook - Fundamentals and the HVAC system used was a window-mounted heat pump. The weather file used in the simulation was customized for the year 2008 from the National Renewable Energy Laboratory (NREL) website. All EnergyPlus inputs were ensured to match closely with the experimental parameters. The simulation results yielded comparable trends with the experimental energy consumption values, however time shifts were not observed. Several other parametric studies like varying PCM thermal conductivity, temperature range, location, insulation R-value and combination of different PCMs were analyzed and results are presented. It was found that a PCM with a melting point from 23 to 27 °C led to maximum energy savings and greater peak load time shift duration, and is more suitable than other PCM temperature ranges for light weight building construction in Phoenix.
ContributorsMuruganantham, Karthik (Author) / Phelan, Patrick (Thesis advisor) / Reddy, Agami (Committee member) / Lee, Taewoo (Committee member) / Arizona State University (Publisher)
Created2010
Description
Despite efforts to recruit and retain female engineering students, only about 21.3% of bachelor’s degrees each year in engineering and computer science are awarded to women. The purpose of this synthesis is to understand the ways in which current research has explored how self-identity, engineering identity, and sense of belonging influence undergraduate women’s persistence. Analysis is focused around 4 themes that emerged: (1) Sense of Self: Self-Efficacy, Expectancy Value Theory; (2) Culture of Engineering: Engineering Identity; (3) Stereotype Threat; (4) Interdisciplinary Studies to Expand the Culture of Engineering. Conclusions of this synthesis may be used as opportunities for future engagement with these topics.
ContributorsTapia, Kayla (Author) / Ganesh, Tirupalavanam (Thesis director) / Velez, Jennifer (Committee member) / Computer Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Engineering has historically been dominated by White men. However, in modern history, engineering is becoming more diverse as the opportunity to pursue engineering has become accessible to people of all races and genders. Yet, college ready high school students from nontraditional backgrounds—women, ethnic minorities, first-generation-to-college students, and those with financial need—often lack exposure to engineering, thus reducing their likelihood to pursue a career in this field. To create engineering learning experiences that can be expanded to a traditional high school science classroom, the Young Engineers Shape the World program at Arizona State University was consulted. The Young Engineers Shape the World program encourages women, notably the most underrepresented group in the engineering field, as well as other students of diverse backgrounds, to pursue engineering. The goal of this effort was to create a 3-contact hour chemical engineering based learning experience to help students in grades 10-11 learn about an application of chemical engineering. Using knowledge of chemical engineering, a soil pH testing activity was created, simulating a typical high school chemistry science experiment. In addition to measuring pH, students were asked to build a modern garden that contained a physical barrier that could protect the garden from acid rain while still allowing sunlight to reach the plant. Student feedback was collected in the form of an experience evaluation survey after each experience. Students found that the soil-moisture quality testing and design of a protective barrier was engaging. However, an iterative curriculum redesign-implement-evaluate effort is needed to arrive at a robust chemical engineering based design learning experience.
ContributorsOtis, Timothy Kevin (Author) / Ganesh, Tirupalavanam (Thesis director) / Schoepf, Jared (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Nuclear power has recently experienced a resurgence in interest due to its ability to generate significant amounts of relatively clean energy. However, the overall size of nuclear power plants still poses a problem to future advancements. The bulkiness of components in the plant contribute to longer construction times, higher building and maintenance costs, and the isolation of nuclear plants from populated areas. The goal of this project was to analyze the thermal performance of nanocrystalline copper tantalum (NC Cu-Ta) inside the steam generator of a pressurized water reactor to see how much the size of these units could be reduced without affecting the amount of heat transferred through it. The analysis revealed that using this material, with its higher thermal conductivity than the traditional Inconel Alloy 600 that is typically used in steam generators, it is possible to reduce the height of a steam generator from 21 meters to about 18.6 meters, signifying a 11.6% reduction in height. This analysis also revealed a diminishing return that occurs with increasing the thermal conductivity on both reducing the required heat transfer area and increasing the overall heat transfer coefficient.
ContributorsRiese, Alexander (Author) / Phelan, Patrick (Thesis director) / Bocanegra, Luis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Based on James Marcia's theory, identity development in youth is the degree to which one has explored and committed to a vocation [1], [2]. During the path to an engineering identity, students will experience a crisis, when one's values and choices are examined and reevaluated, and a commitment, when the outcome of the crisis leads the student to commit to becoming an engineer. During the crisis phase, students are offered a multitude of experiences to shape their values and choices to influence commitment to becoming an engineering student. Student's identities in engineering are fostered through mentoring from industry, alumni, and peer coaching [3], [4]; experiences that emphasize awareness of the importance of professional interactions [5]; and experiences that show creativity, collaboration, and communication as crucial components to engineering. Further strategies to increase students' persistence include support in their transition to becoming an engineering student, education about professional engineers and the workplace [6], and engagement in engineering activities beyond the classroom. Though these strategies are applied to all students, there are challenges students face in confronting their current identity and beliefs before they can understand their value to society and achieve personal satisfaction. To understand student's progression in developing their engineering identity, first year engineering students were surveyed at the beginning and end of their first semester. Students were asked to rate their level of agreement with 22 statements about their engineering experience. Data included 840 cases. Items with factor loading less than 0.6 suggesting no sufficient explanation were removed in successive factor analysis to identify the four factors. Factor analysis indicated that 60.69% of the total variance was explained by the successive factors. Survey questions were categorized into three factors: engineering identity as defined by sense of belonging and self-efficacy, doubts about becoming an engineer, and exploring engineering. Statements in exploring engineering indicated student awareness, interest and enjoyment within engineering. Students were asked to think about whether they spent time learning what engineers do and participating in engineering activities. Statements about doubts about engineering to engineering indicated whether students had formed opinions about their engineering experience and had understanding about their environment. Engineering identity required thought in belonging and self-efficacy. Belonging statements called for thought about one's opinion in the importance of being an engineer, the meaning of engineering, an attachment to engineering, and self-identification as an engineer. Statements about self-efficacy required students to contemplate their personal judgement of whether they would be able to succeed and their ability to become an engineer. Effort in engineering indicated student willingness to invest time and effort and their choices and effort in their engineering discipline.
ContributorsNguyen, Amanda (Author) / Ganesh, Tirupalavanam (Thesis director) / Robinson, Carrie (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05