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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

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

This paper explores to mitigate the issue of Formula SAE brakes vaporizing by creating a computational model to determine when the fluid may boil given a velocity profile and brake geometry. The paper explores various parameters and assumptions and how they may lead to error determining when the brake fluid

This paper explores to mitigate the issue of Formula SAE brakes vaporizing by creating a computational model to determine when the fluid may boil given a velocity profile and brake geometry. The paper explores various parameters and assumptions and how they may lead to error determining when the brake fluid will vaporize. Common assumptions such as a constant convection coefficient are questioned throughout the paper and compared to methods requiring higher computational power. Throughout this model, a significant dependence on the heat partition factor is found on the final steady state temperature of the brake fluid is found, and a sensitivity analysis is performed to determine the effect of its variation.

ContributorsWesterhoff, Andrew (Author) / Kwon, Beomjin (Thesis director) / Milcarek, Ryan (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2023-05
Description

Thermophotovoltaic energy conversion is seen as a viable option for efficiently converting heat to electricity. There are three key components to a thermophotovoltaic (TPV) system: a heat source, a heat emitter and a photovoltaic (PV) cell. A heat source heats up the emitter which causes the emitter to release thermal

Thermophotovoltaic energy conversion is seen as a viable option for efficiently converting heat to electricity. There are three key components to a thermophotovoltaic (TPV) system: a heat source, a heat emitter and a photovoltaic (PV) cell. A heat source heats up the emitter which causes the emitter to release thermal radiation. The photons are absorbed by a PV cell when they are acting above the bandgap energy. The PV cell then generates electricity from this thermal radiation. In theory, efficiency of a TPV system can be well above 50%. In order for TPV to reach large-scale adaptation, an efficiency at or above 20% is needed. In this project, a high-temperature heater capable of reaching 1000K was developed. The heater involved a copper block machined to hold two cartridge heaters, as well as two thermocouples. It has an accompanying copper lid that can be screwed tight to the main block, with an emitter in between. There is an aperture to allow radiation through the casing towards the PV cell. Preliminary thermal analysis showed that the heater provides uniform temperature distribution across the emitter, which is necessary for proper radiation. A mounting system was also designed to implement the heater into the overall TPV system. Current work is being done to lower the radiation loss from the heater and mounting system, as well as implementation of all auxiliary components to begin testing. The maximum temperature of the heater, radiation heat flux received by the cell, and overall power output and efficiency of the system will be tested.

ContributorsDeffigos, Nikolas (Author) / Wang, Liping (Thesis director) / Milcarek, Ryan (Committee member) / Ni, Qing (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2021-12
Description
This thesis explores the melting optimization of phase change materials (PCMs) in a concentric pipe setup with a focus on improving heat transfer efficiency for latent heat thermal energy storage (LHTES) systems. The primary objective is to investigate the effects of varying the number of fins, as well as introducing

This thesis explores the melting optimization of phase change materials (PCMs) in a concentric pipe setup with a focus on improving heat transfer efficiency for latent heat thermal energy storage (LHTES) systems. The primary objective is to investigate the effects of varying the number of fins, as well as introducing bifurcations along the fin length, to optimize the time it takes to fully melt the PCM matrix. The work begins by verifying the accuracy of the Ansys Fluent simulations using the Stefan analytical solution, a well-established method for 1D melting processes. MATLAB was used to plot the Stefan solution, determining the time required to melt a 1mm block of ice with a boundary temperature slightly above freezing. This was subsequently compared to results obtained from Ansys Fluent, both of which showed consistency in melting times and temperature distributions, validating the simulation approach. Next, thermal resistance modeling is utilized to establish both upper and lower bounds for melting times, considering the slowest and fastest possible rates. The analysis introduces the use of shape factors, a geometric parameter critical to determining the thermal resistance between the inner and outer pipes in the concentric setup. The derived thermal resistance and subsequent equations provide a conservative estimate of the slowest time to melt, which is ~38,078 seconds. Similarly, the fastest melting time is calculated by equating shape factors to convective heat transfer coefficients, yielding a much shorter time of ~1,339 seconds. These bounds provide a critical "gut check" for the results observed in the simulation phase. The first stage of optimization explores the effect of increasing the total number of fins in the concentric pipe setup. Initially, a base model with four fins was tested, and then simulations were conducted for setups with up to 13 fins. The total fin area was kept constant while adjusting the fin length accordingly. Results revealed that the optimal number of fins, in terms of minimizing the total melt time, falls between 5 and 6, with the fastest time achieved at 6 fins. This finding highlights that as the number of fins increases beyond this point, the effectiveness of heat transfer diminishes due to fin crowding. The second stage introduces bifurcations along the fins, which further improve heat transfer by extending more surface area into the PCM matrix. The bifurcations were analyzed at various points along the fin length, ranging from 20% to 80% of the total length. A detailed simulation study revealed that the optimal configuration consists of 5 fins with bifurcations beginning at 20% of the fin length, significantly reducing melt times compared to non-bifurcated setups. Overall, this research demonstrates that by optimizing both the number of fins and the introduction of bifurcations, substantial improvements can be made to the efficiency of PCM melting in LHTES systems. The findings offer important insights for the design of heat exchangers and thermal storage systems, emphasizing the importance of balancing geometric factors to maximize heat transfer.
ContributorsCerullo, Aiden (Author) / Wilbur, Joshua (Thesis director) / Wang, Robert (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2024-12
Description
This project presents the design and simulation of a compact, energy-efficient water chiller system tailored for cold plunge applications, addressing the inefficiencies of traditional ice-based methods. The system aims to efficiently chill water to 5°C by optimizing heat transfer, cooling time, and energy consumption. Using R-134a as the refrigerant, the

This project presents the design and simulation of a compact, energy-efficient water chiller system tailored for cold plunge applications, addressing the inefficiencies of traditional ice-based methods. The system aims to efficiently chill water to 5°C by optimizing heat transfer, cooling time, and energy consumption. Using R-134a as the refrigerant, the refrigeration cycle was modeled in Simulink to evaluate key parameters, including cooling load, coefficient of performance, and power consumption. The simulation identified an optimal water pump flow rate of 0.171 kg/s, achieving a cooling time of under 8 hours and a system efficiency of 3.51. The study demonstrates the feasibility of integrating compact refrigeration systems into personal or small-scale wellness setups, laying the groundwork for future experimental validation and design refinement.
ContributorsFitzgerald, Kenneth (Author) / Wilbur, Joshua (Thesis director) / Andersen, Erik (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2025-05
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

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
The ASU Compact X-ray Free Electron Laser (CXFEL) is a first of its kind instrument that will illuminate the processes of life and allow scientists to create more effective treatments for disease. The dimensions of the linear accelerator (LINAC) cavities must remain stable during operation, for a change in the

The ASU Compact X-ray Free Electron Laser (CXFEL) is a first of its kind instrument that will illuminate the processes of life and allow scientists to create more effective treatments for disease. The dimensions of the linear accelerator (LINAC) cavities must remain stable during operation, for a change in the geometry alters the standing wave microwave energy resonance within the cavities and leads to reflected rather than coupled and useful microwave energy to electric field coupling. This disturbs the electron bunch acceleration dynamics critical to the ultimate generation of x-ray pulses. Cooling water must be supplied to the electron generating RF-GUN, and linear accelerator (LINAC) structures at unique flowrate and temperature setpoints that are specific to the operating mode of the CXFEL. Design specifications for the water supply to the RF-GUN and three LINACs and were made for the nominal operating mode, which adds a 3 kW heat load to the water. To maintain steady cavity dimensions, water must be supplied to each device under test at 30.0 ºC ± 0.06 ºC. The flowrate of water must be 3.5 GPM to the RF-GUN and 2.5 GPM to each of the three LINACs with ± 0.01 GPM flowrate resolution. The primary function of the Dedicated-Precision Thermal Trim Unit (D-PTTU) is to control the flowrate and temperature of water supply to each device under test. A simplified model of the system was developed to select valves that would meet our design specifications for flowrate and temperature control. After using this model for valve selection, a detailed system model was created to simulate relevant coupled-domain physics of the integrated system. The detailed system model was used to determine the critical sensitivities of the system and will be used to optimize the performance of the system in the future. Before the detailed system model can be verified and tuned with experiments, the sensors were calibrated in an ice-bath to ensure the sensors measure accurate and precise values. During initial testing, the D-PTTU was able to achieve ± 0.02 ºC temperature resolution, which exceeds the design specification by a factor of three.
ContributorsGardeck, Alex John (Author) / Holl, Mark (Thesis director) / Smith, Dean (Committee member) / Department of Physics (Contributor) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This thesis project explains what thermal interface materials (TIMs) are, what they are used for, and how to measure their properties. Thermal interface materials are typically either a grease like paste or a soft polymer pad that is placed between two solids to increase the heat transfer rate. Solids in

This thesis project explains what thermal interface materials (TIMs) are, what they are used for, and how to measure their properties. Thermal interface materials are typically either a grease like paste or a soft polymer pad that is placed between two solids to increase the heat transfer rate. Solids in contact with each other experience a very large thermal contact resistance, this creates a thermal bottleneck which severely decreases the heat transfer from one solid to another. To solve this, particles with a high thermal conductivity are used as filler material in either a grease or polymer. A common application for TIMs is in computer components, where a TIM is used to remove the heat generated from computer chips. These materials allow for computer chips to run faster without overheating or throttling performance. However, further improvements to TIMs are still desired, which are needed for more powerful computer chips. In this work, a Stepped Bar Apparatus (SBA) is used to evaluate the thermal properties of TIMs. The SBA is based on Fourier’s Law of one-dimensional heat transfer. This work explains the fundamentals of the SBA measurement, and develops a reliable way to confirm the SBA’s measurement consistency through the use of reference samples. Furthermore, this work evaluates the effects of volume fraction and magnetic alignment on the performance of nickel flakes mixed into a polymer to create a soft TIM composite pad. Magnets are used to align the nickel flakes into a column like arrangement in the direction that heat will travel. Magnetic alignment increases the thermal conductivity of the composite pads, and has peak performance at low compression.
ContributorsHart, Matthew (Author) / Rykaczewski, Konrad (Thesis director) / Wang, Robert (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
The temperature of exhaust pipes can be dangerous in dry areas where there is a lot of brush. The temperatures of exhaust pipes can reach a high enough temperature to start a fire if touching the dry brush, which ignites around 300°C. The goal of this project was to explore

The temperature of exhaust pipes can be dangerous in dry areas where there is a lot of brush. The temperatures of exhaust pipes can reach a high enough temperature to start a fire if touching the dry brush, which ignites around 300°C. The goal of this project was to explore different techniques to limit the possibility of these brush fires. Specifically, different methods were explored to reduce the temperature of the pipe that would be contacting the brush. Fires can begin within seconds of contacting the hot exhaust pipes [10]. This experiment found that of the three options tested: exhaust wrap, heat sink with thermoelectric devices, and high temperature paint, adding a heat shield/sink is the best way to limit the high temperatures from igniting the brush. There was a cooling difference of nearly 100°C when a heat shield/sink was added to the bare pipe. The additional thermal mass as well as the finned heat sinks attached to the heat sink helped dissipate the heat from the pipe and release the waste heat into the surroundings. The increase in surface area in correspondence with forced convection from the surrounding air lowered the temperature of the metal in contact with the dry brush.
ContributorsHodges, Andrew (Author) / Benson, David (Thesis director) / Bocanegra, Luis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This paper presents an experimental investigation into the effects of altering electrode surface area roughness on thermogalvanic cell performance. A temperature difference between two electrodes was induced and brought to steady state to achieve a difference of around 50 °C, which was maintained with a DC power generated hot wire

This paper presents an experimental investigation into the effects of altering electrode surface area roughness on thermogalvanic cell performance. A temperature difference between two electrodes was induced and brought to steady state to achieve a difference of around 50 °C, which was maintained with a DC power generated hot wire and a pumped ice bath. The open-circuit voltage values at steady-state were measured by a programed multimeter and the temperatures were measured by a series of type K thermocouples. Electrode surface area roughness was altered using different grit values of sandpaper and measuring the values using a Zescope Optical Profilometer. Once three different surface area average values were achieved, 6 trials were performed with 2 trials per roughness value. The results were tabulated in Section 4 of this report.
It was predicted that increasing the surface area roughness would increase the number of electrons present in the reduction oxidation reaction and decrease the activation resistance of the thermogalvanic system. Decreasing the activation resistance, a component of total internal resistance, would therefore increase the power output of the cell by a small magnitude. The results showed that changing the surface area roughness of the Copper electrodes evidently had no effect on the outputs of the cell system. Additionally, the Seebeck coefficient was also unaffected by the presence of increased surface area roughness.
The work presented in the following paper is part of a continuing effort to better understand the performance of thermogalvanic cells and their heat to electrical energy transfer properties.
ContributorsLopez, Maggie Marie (Author) / Phelan, Patrick (Thesis director) / Miner, Mark (Committee member) / School of Sustainability (Contributor) / School of Music (Contributor) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05