Matching Items (25)
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- All Subjects: engineering
- All Subjects: photovoltaics
- 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
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
An investigation is undertaken of a prototype building-integrated solar photovoltaic-powered thermal storage system and air conditioning unit. The study verifies previous thermodynamic and economic conclusions and provides a more thorough analysis. A parameterized model was created for optimization of the system under various conditions. The model was used to evaluate energy and cost savings to determine viability of the system in several circumstances, such as a residence in Phoenix with typical cooling demand. The proposed design involves a modified chest freezer as a thermal storage tank with coils acting as the evaporator for the refrigeration cycle. Surrounding the coils, the tank contains small containers of water for high-density energy storage submerged in a low freezing-point solution of propylene glycol. The cooling power of excess photovoltaic and off-peak grid power that is generated by the air conditioning compressor is stored in the thermal storage tank by freezing the pure water. It is extracted by pumping the glycol across the ice containers and into an air handler to cool the building. Featured results of the modeling include the determination of an optimized system for a super-peak rate plan, grid-connected Phoenix house that has a 4-ton cooling load and requires a corresponding new air conditioner at 4.5 kW of power draw. Optimized for the highest payback over a ten year period, the system should consist of a thermal storage tank containing 454 liters (120 gallons) of water, a 3-ton rated air conditioning unit, requiring 2.7 kW, which is smaller than conventionally needed, and no solar photovoltaic array. The monthly summer savings would be $45.The upfront cost would be $5489, compared to a conventional system upfront cost of $5400, for a payback period of 0.33 years. Over ten years, this system will provide $2600 of savings. To optimize the system for the highest savings over a twenty year period, a thermal storage tank containing 272 liters (72 gallons) of water, a 40-m2 photovoltaic array with 15% efficiency, and a 3.5-ton, 3.1-kW rated air conditioning unit should be installed for an upfront cost of $19,900. This would provide monthly summer savings of $225 and 1062 kWh grid electricity, with a payback period of only 11 years and a total cost savings of $12,300 over twenty years. In comparison, a system with the same size photovoltaic array but without storage would result in a payback period of 16 years. Results are also determined for other cooling requirements and installation sizes, such that the viability of this type of system in different conditions can be discussed. The use of this model for determining the optimized system configuration given different constraints is also described.
ContributorsMagerman, Beth Francine (Author) / Phelan, Patrick (Thesis director) / Goodnick, Stephen (Committee member) / Chhetri, Nalini (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2013-05
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
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
As Energy needs grow and photovoltaics expand to meet humanity’s demand for electricity, waste modules will start building up. Tao et. al. propose a recycling process to recover all precious solar cell materials, a process estimated to generate a potential $15 billion in revenue by 2050. A key part of this process is metal recovery, and specifically, silver recovery. Silver recovery via electrowinning was studied using a hydrofluoric acid leachate/electrolyte. Bulk electrolysis trials were performed at varied voltages using a silver working electrode, silver pseudo-reference electrode and a graphite counter-electrode. The highest mass recovery achieved was 98.8% which occurred at 0.65 volts. Product purity was below 90% for all trials and coulombic efficiency never reached above 20%. The average energy consumption per gram of reduced silver was 2.16kWh/kg. Bulk electrolysis indicates that parasitic reactions are drawing power from the potentiostat and limiting the mass recovery of the system. In order to develop this process to the practical use stage, parasitic reactions must be eliminated, and product purity and power efficiency must improve. The system should be run in a vacuum environment and the reduction peaks in the cell should be characterized using cyclic voltammetry.
ContributorsTezak, Cooper R (Author) / Tao, Meng (Thesis director) / Phelan, Patrick (Committee member) / Chemical Engineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
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
Buildings continue to take up a significant portion of the global energy consumption, meaning there are significant research opportunities in reducing the energy consumption of the building sector. One widely studied area is waste heat recovery. The purpose of this research is to test a prototype thermogalvanic cell in the form factor of a UK metric brick sized at 215 mm × 102.5 mm × 65 mm for the experimental power output using a copper/copper(II) (Cu/Cu2+) based aqueous electrode. In this study the thermogalvanic brick uses a 0.7 M CuSO4 + 0.1 M H2SO4 aqueous electrolyte with copper electrodes as two of the walls. The other walls of the thermogalvanic brick are made of 5.588 mm (0.22 in) thick acrylic sheet. Internal to the brick, a 0.2 volume fraction minimal surface Schwartz diamond (Schwartz D) structure made of ABS, Polycarbonate-ABS (PCABS), and Polycarbonate-Carbon Fiber (PCCF) was tested to see the effects on the power output of the thermogalvanic brick. By changing the size of the thermogalvanic cell into that of a brick will allow this thermogalvanic cell to become the literal building blocks of green buildings. The thermogalvanic brick was tested by applying a constant power to the strip heater attached to the hot side of the brick, resulting in various ∆T values between 8◦C and 15◦C depending on the material of Schwartz D inside. From this, it was found that a single Cu/Cu2+ thermogalvanic brick containing the PCCF or PCABS Schwartz D performed equivalently well at a 163.8% or 164.9%, respectively, higher normalized power density output than the control brick containing only electrolyte solution.
ContributorsLee, William J. (Author) / Phelan, Patrick (Thesis advisor) / El Asmar, Mounir (Committee member) / Milcarek, Ryan (Committee member) / Arizona State University (Publisher)
Created2018
Description
First, in a large-scale structure, a 3-D CFD model was built to simulate flow and temperature distributions. The flow patterns and temperature distributions are characterized and validated through spot measurements. The detailed understanding of them then allows for optimization of the HVAC configuration because identification of the problematic flow patterns and temperature mis-distributions leads to some corrective measures. Second, an appropriate form of the viscous dissipation term in the integral form of the conservation equation was considered, and the effects of momentum terms on the computed drop size in pressure-atomized sprays were examined. The Sauter mean diameter (SMD) calculated in this manner agrees well with experimental data of the drop velocities and sizes. Using the suggested equation with the revised treatment of liquid momentum setup, injection parameters can be directly input to the system of equations. Thus, this approach is capable of incorporating the effects of injection parameters for further considerations of the drop and velocity distributions under a wide range of spray geometry and injection conditions. Lastly, groundwater level estimation was investigated using compressed sensing (CS). To satisfy a general property of CS, a random measurement matrix was used, the groundwater network was constructed, and finally the l-1 optimization was run. Through several validation tests, correct estimation of groundwater level by CS was shown. Using this setup, decreasing trends in groundwater level in the southwestern US was shown. The suggested method is effective in that the total measurements of registered wells can be reduced down by approximately 42 %, sparse data can be visualized and a possible approach for groundwater management during extreme weather changes, e.g. in California, was demonstrated.
ContributorsLee, Joon Young (Author) / Lee, Taewoo (Thesis advisor) / Huang, Huei-Ping (Committee member) / Lopez, Juan (Committee member) / Phelan, Patrick (Committee member) / Chen, Kangping (Committee member) / Arizona State University (Publisher)
Created2015