Matching Items (22)
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- All Subjects: energy
- Creators: Mechanical and Aerospace Engineering Program
- Creators: Wang, Robert
- Member of: Theses and Dissertations
Description
A relatively simple subset of nanotechnology - nanofluids - can be obtained by adding nanoparticles to conventional base fluids. The promise of these fluids stems from the fact that relatively low particle loadings (typically <1% volume fractions) can significantly change the properties of the base fluid. This research explores how low volume fraction nanofluids, composed of common base-fluids, interact with light energy. Comparative experimentation and modeling reveals that absorbing light volumetrically (i.e. in the depth of the fluid) is fundamentally different from surface-based absorption. Depending on the particle material, size, shape, and volume fraction, a fluid can be changed from being mostly transparent to sunlight (in the case of water, alcohols, oils, and glycols) to being a very efficient volumetric absorber of sunlight. This research also visualizes, under high levels of irradiation, how nanofluids undergo interesting, localized phase change phenomena. For this, images were taken of bubble formation and boiling in aqueous nanofluids heated by a hot wire and by a laser. Infrared thermography was also used to quantify this phenomenon. Overall, though, this research reveals the possibility for novel solar collectors in which the working fluid directly absorbs light energy and undergoes phase change in a single step. Modeling results indicate that these improvements can increase a solar thermal receiver's efficiency by up to 10%.
ContributorsTaylor, Robert (Author) / Phelan, Patrick E (Thesis advisor) / Adrian, Ronald (Committee member) / Trimble, Steve (Committee member) / Posner, Jonathan (Committee member) / Maracas, George (Committee member) / Arizona State University (Publisher)
Created2011
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
A low cost expander, combustor device that takes compressed air, adds thermal energy and then expands the gas to drive an electrical generator is to be designed by modifying an existing reciprocating spark ignition engine. The engine used is the 6.5 hp Briggs and Stratton series 122600 engine. Compressed air that is stored in a tank at a particular pressure will be introduced during the compression stage of the engine cycle to reduce pump work. In the modified design the intake and exhaust valve timings are modified to achieve this process. The time required to fill the combustion chamber with compressed air to the storage pressure immediately before spark and the state of the air with respect to crank angle is modeled numerically using a crank step energy and mass balance model. The results are used to complete the engine cycle analysis based on air standard assumptions and air to fuel ratio of 15 for gasoline. It is found that at the baseline storage conditions (280 psi, 70OF) the modified engine does not meet the imposed constraints of staying below the maximum pressure of the unmodified engine. A new storage pressure of 235 psi is recommended. This only provides a 7.7% increase in thermal efficiency for the same work output. The modification of this engine for this low efficiency gain is not recommended.
ContributorsJoy, Lijin (Author) / Trimble, Steve (Thesis advisor) / Davidson, Joseph (Committee member) / Phelan, Patrick (Committee member) / Arizona State University (Publisher)
Created2011
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
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
The following document addresses two grand challenges posed to engineers: to make solar energy economically viable and to restore and improve urban infrastructure. Design solutions to these problems consist of the preliminary designs of two energy systems: a Packaged Photovoltaic (PPV) energy system and a natural gas based Modular Micro Combined Cycle (MMCC) with 3D renderings. Defining requirements and problem-solving approach methodology for generating complex design solutions required iterative design and a thorough understanding of industry practices and market trends. This paper briefly discusses design specifics; however, the major emphasis is on aspects pertaining to economical manufacture, deployment, and subsequent suitability to address the aforementioned challenges. The selection of these systems is based on the steady reduction of PV installation costs in recent years (average among utility, commercial, and residential down 27% from Q4 2012 to Q4 2013) and the dramatic decline in natural gas prices to $5.61 per thousand cubic feet. In addition, a large number of utility scale coal-based power plants will be retired in 2014, many due to progressive emission criteria, creating a demand for additional power systems to offset the capacity loss and to increase generating capacity in order to facilitate the ever-expanding world population. The proposed energy systems are not designed to provide power to the masses through a central location. Rather, they are intended to provide economical, reliable, and high quality power to remote locations and decentralized power to community-based grids. These energy systems are designed as a means of transforming and supporting the current infrastructure through distributed electricity generation.
ContributorsSandoval, Benjamin Mark (Author) / Bryan, Harvey (Thesis director) / Fonseca, Ernesto (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
Description
The global energy demand is expected to grow significantly in the next several decades and support for energy generation with high carbon emissions is continuing to decline. Alternative methods have gained interest, and wind energy has established itself as a viable source. Standard wind farms have limited room for growth and improvement, so wind energy has started to explore different directions. The urban environment is a potential direction for wind energy due to its proximity to the bulk of energy demand. CFD analysis has demonstrated that the presence of buildings can accelerate wind speeds between buildings and on rooftops. However, buildings generate areas of increased turbulence at their surface. The turbulence thickness and intensity vary with roof shape, building height, and building orientation. The analysis has concluded that good wind resource is possible in the urban environment in specific locations. With that, turbine selection becomes very important. A comparison has concluded that vertical axis wind turbines are more useful in the urban environment than horizontal axis wind turbines. Furthermore, building-augmented wind turbines are recommended because they are architecturally integrated into a building for the specific purpose of generating more energy. The research has concluded that large-scale generation in the urban environment is unlikely to be successful, but small-scale generation is quite viable. Continued research and investigation on urban wind energy is recommended.
ContributorsKlumpers, Ryan Scott (Author) / Calhoun, Ronald (Thesis director) / Huang, Huei-Ping (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
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
Each year, the average vehicle contributes 4.6 metric tons of carbon dioxide into the atmosphere [1]. These gases contribute to around 30,000 premature deaths each year [2] and are linked to in the increase in cases of Asthma. Human health is further impacted by the increase of greenhouse gasses in the atmosphere. Rays from the sun travel to the Earth where they are absorbed. Absorbing the sun’s rays heats up the Earth which is then radiated into space. Greenhouse gasses inhibit this process much like the glass walls in a greenhouse. As a result, the temperature of the Earth steadily increases. The greenhouse effect is dangerous because it can be linked to natural disasters, rising ocean levels, and extinction of species. One of the biggest contributors to the greenhouse effect is burning fossil fuels. Powerplants, agriculture, and transportation are some of the largest contributors to the increase of atmospheric carbon dioxide. To mitigate the effects of transportation, car companies have invested into production of alternative and renewable fuels for their products. One of the sources which has gained popularity recently, is the use of electricity to power our vehicles. Tesla has spearheaded the electric car movement and is largely responsible for this beneficial shift. One issue with this approach is that a majority, around 76.3%, of Americans drive alone on their commute [13]. The market in its current state encourages inefficient transportation due to the lack of alternatives. While motorcycles may offer a more eco-friendly and economical approach to cars, many are afraid of potential hazards of using this mode of transportation. The introduction of electric bikes offers an interesting approach to improving this efficiency and safety issue. The wide availability to customers offers an alternative which pushes the traditional distance limits for commuting on a bicycle. Since the market is relatively new, several issues pose challenges to consumers. This research aims to clarify and analyze the electric bike market in order to supply a potential customer with the tools needed to acquire a high quality and reasonably price bike.
ContributorsFriedrich, Collin Anthony (Author) / Lee, Hyunglae (Thesis director) / Lacy, Gerald (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This paper analyzes Burkina Faso’s Souro Sanou University Hospital Center’s energy needs and discusses whether or not solar panels are a good investment. This paper also discusses a way to limit the damage caused by power outages. The hospital has a history of problems with power outages; in the summer they have power outages every other day lasting between one to four hours, and in the rainy season they have outages once every other week lasting the same amount of time.
The first step in this analysis was collecting relevant data which includes: location, electricity rates, energy consumption, and existing assets. The data was entered into a program called HOMER. HOMER is a program which analyzes an electrical system and determines the best configuration and usage of assets to get the lowest levelized cost of energy (LCOE). In HOMER, five different analyses were performed. They reviewed the hospital’s energy usage over 25 years: the current situation, one of the current situation with added solar panels, and another where the solar panels have single axis tracking. The other two analyses created incentives to have more solar panels, one situation with net metering, and one with a sellback rate of 0.03 $/kWh. The result of the analysis concluded that the ideal situation would have solar panels with a capacity of 300 kW, and the LCOE in this situation will be 0.153 $/kWh. The analysis shows that investing in solar panels will save the hospital approximately $65,500 per year, but the initial investment of $910,000 only allows for a total savings of $61,253 over the life of the project. The analysis also shows that if the electricity company, Sonabel, eventually buys back electricity then net metering would be more profitable than reselling electricity for the hospital.
Solar panels will help the hospital save money over time, but they will not stop power outages from happening at the hospital. For the outages to stop affecting the hospital’s operations they will have to invest in an uninterrupted power supply (UPS). The UPS will power the hospital for the time between when the power goes out and when their generators are turning on which makes it an essential investment. This will stop outages from affecting the hospital, and if the power goes out during the day then the solar panels can help supplement the energy production which will take some of the strain from their generators.
The results of this study will be sent to officials at the hospital and they can decide if the large initial investment justifies the savings. If the solar panels and UPS can save one life, then maybe the large initial investment is worth it.
The first step in this analysis was collecting relevant data which includes: location, electricity rates, energy consumption, and existing assets. The data was entered into a program called HOMER. HOMER is a program which analyzes an electrical system and determines the best configuration and usage of assets to get the lowest levelized cost of energy (LCOE). In HOMER, five different analyses were performed. They reviewed the hospital’s energy usage over 25 years: the current situation, one of the current situation with added solar panels, and another where the solar panels have single axis tracking. The other two analyses created incentives to have more solar panels, one situation with net metering, and one with a sellback rate of 0.03 $/kWh. The result of the analysis concluded that the ideal situation would have solar panels with a capacity of 300 kW, and the LCOE in this situation will be 0.153 $/kWh. The analysis shows that investing in solar panels will save the hospital approximately $65,500 per year, but the initial investment of $910,000 only allows for a total savings of $61,253 over the life of the project. The analysis also shows that if the electricity company, Sonabel, eventually buys back electricity then net metering would be more profitable than reselling electricity for the hospital.
Solar panels will help the hospital save money over time, but they will not stop power outages from happening at the hospital. For the outages to stop affecting the hospital’s operations they will have to invest in an uninterrupted power supply (UPS). The UPS will power the hospital for the time between when the power goes out and when their generators are turning on which makes it an essential investment. This will stop outages from affecting the hospital, and if the power goes out during the day then the solar panels can help supplement the energy production which will take some of the strain from their generators.
The results of this study will be sent to officials at the hospital and they can decide if the large initial investment justifies the savings. If the solar panels and UPS can save one life, then maybe the large initial investment is worth it.
ContributorsSchmidt, Evin Khalil (Author) / Johnson, Nathan (Thesis director) / Miner, Mark (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05