Heat Transfer, Combustion Commons^™

An Investigative Study Of Thermal Fluid Properties When Introducing Metallic Nanoparticles Through A Heat Exchanging System, Levi P. Mckinney

College of Graduate Studies: Theses & Dissertations

Heat-exchanging systems are essential in applications ranging from automobiles to air-conditioning units, and ongoing improvements aim to enhance efficiency while reducing system size. Conventional coolant upgrades often rely on ethylene glycol, which increases thermal stability and lowers freezing point but reduces water’s inherent heat-transfer capability. Advances in nanotechnology provide an alternative approach: suspending nanoparticles in base fluids can significantly modify thermal properties, with some formulations exhibiting conductivity increases of up to 60%. This thesis examines the thermal and tribological performance of three working fluids—distilled water, a 50:50 water–ethylene glycol mixture, and the same mixture enhanced with Al₂O₃ nanoparticles. Distilled water …

Investigation Of Conductive Die-Top Thermal Capacitors During Short Circuit Operation Of Silicon Carbide Devices, Youssef Abotaleb

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Silicon carbide (SiC) power devices have garnered significant attention in recent years due to their superior thermal and electrical properties compared to traditional silicon devices. However, SiC power devices suffer from severe reliability issues arising from their mechanical properties. This is because the Young's modulus of SiC is about three times larger than that of silicon, which correspondingly raises the mechanical stresses acting on the bonding structure, often leading to device failure under power shock events.

Traditional packaging materials and designs tend to constrain SiC performance, as hot-spot temperature resulting from a power shock is one of the key factors …

Performance-Tunable Thermal Barrier Coating For Carbon Fiber-Reinforced Plastic Composites Via Flame Spraying, Heejin Kim, Kandasamy Praveen, Min Wook Lee, Juhyeong Lee

Mechanical and Aerospace Engineering Faculty Publications

Thermal barrier coatings (TBCs) are essential for improving the heat resistance of materials operating in high-temperature environments. This paper proposes a new method for manufacturing double-layered TBC with graded porosity for carbon fiber-reinforced plastic (CFRP) composites. The TBC was created by a flame spraying process, consisting of relatively dense and porous layers: (1) a dense layer was produced by spraying yttria-stabilized zirconia (YSZ) particles directly onto neat carbon fabric substrate and (2) a porous layer was prepared by co-spraying YSZ particles with sacrificial polyetheretherketone (PEEK) particles. The porosity of the porous layer was controlled by varying a PEEK injection distance …

Thermal Conductivity Of Thin Porous Ceramic Coatings: An Analytical And Experimental Study, Lei Zhao

Theses and Dissertations

An analytical model of the thermal conductivity of the porous yttrium-stabilized zirconia (YSZ) layer used in the thermal barrier coatings (TBCs) is presented. Such high-temperature resistant coatings are essential to protect the metallic components of gas turbine engines. The model calculates the conductivity based on the coating's porosity, pore size distribution, and pore morphology, including the individual pore cross-section area, aspect ratio, and orientation, which are extracted from the scanning electron microscopy images. The model was verified through comparisons with numerical simulation results from a multiphysics software tool. A laser temperature gradient test was performed to validate the analytical model …

Data On The Validation To Determine The Material Thermal Properties Estimation Via A One-Dimensional Transient Convection Model, Lauren B. Tomanek, Daniel S. Stutts

Mechanical and Aerospace Engineering Faculty Research & Creative Works

These data were acquired to estimate the parameters of a closed form solution of a one-dimensional transient convection heat diffusion PDE. The purpose was to demonstrate that the model could be used to determine the thermal conductivity. The system was tested for a wide range of thermal conductivity, 15-400 W/mK, in order to verify that the method was applicable for various materials. The data reported here refer to the study in the research articles, “Material Thermal Properties Estimation Via a One-Dimensional Transient Convection Model” and “Influence of porosity on the thermal, electrical, and mechanical performance of selective laser melted stainless …

Hybridization From Guest-Host Interactions Reduces The Thermal Conductivity Of Metal-Organic Frameworks, Mallory E. Decoster, Hasan Babaei, Sangeun S. Jung, Zeinab M. Hassan, John T. Gaskins, Ashutosh Giri, Emma M. Tiernan, John A. Tomko, Helmut Baumgart, Pamela M. Norris, Alan J.H. Mcgaughey, Christopher E. Wilmer, Engelbert Redel, Gaurav Giri, Patrick E. Hopkins

Electrical & Computer Engineering Faculty Publications

We experimentally and theoretically investigate the thermal conductivity and mechanical properties of polycrystalline HKUST-1 metal–organic frameworks (MOFs) infiltrated with three guest molecules: tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), and (cyclohexane-1,4-diylidene)dimalononitrile (H4-TCNQ). This allows for modification of the interaction strength between the guest and host, presenting an opportunity to study the fundamental atomic scale mechanisms of how guest molecules impact the thermal conductivity of large unit cell porous crystals. The thermal conductivities of the guest@MOF systems decrease significantly, by on average a factor of 4, for all infiltrated samples as compared to the uninfiltrated, pristine HKUST-1. This reduction in thermal conductivity goes in …

Thermal Conductivity Measuring System (Tcoms), Lucas Hill

All Undergraduate Projects

The Mechanical Engineering Technology department at Central Washington University is lacking a method to reliably measure the thermal conductivity of bulk materials, with dimensions of at least a 1 cm radius, within a teaching environment. Thermal Conductivity Measuring System (TCoMS) will be a useful tool to perform these measurements as it is able to obtain measurement readings for materials between 0 C and 50 C within 20 seconds. TCoMS will accomplish this by using the pulse decay method of measuring thermal conductivity, a form of transient heat transfer analysis. This method is performed by generating a pulse of heat at …

Effect Of Adding Palm Fiber To Thermal Conductivity Of Quick Set Concrete, Monica Garcia

Theses and Dissertations

As climate change becomes a more dire issue and more readily accepted by those in power, the demand for local and systemic solutions grows louder. In urban environments, one issue of concern is the contribution of anthropogenic heat from buildings which contributes to localized warming of the environment. A method that can reduce anthropogenic heat is decreasing the thermal conductivity of building materials. The objective of this study is to examine the possibility of using palm fibers to reduce the thermal conductivity of quick-set concrete samples. The data gathered in this study are used to determine the thermal conductivity value …

Study Of The Effective Thermal Conductivity Of Polymer Composites With Varying Filler Arrangements, Debraliz Isaac Aragones, Rajath Kantharaj, Aaditya Candadai, Amy Marconnet

The Summer Undergraduate Research Fellowship (SURF) Symposium

Alternative thermal management solutions for electronic devices are being widely explored due to the increasing heat concentration that results from shrinking sizes and increasing power of modern electronics. Clearly, there is a need to spread the heat effectively in these systems, and polymer composites can potentially provide high thermal conductivity at low filler fraction while maintaining desirable mechanical properties for electronic packaging. The present study aims to investigate the effective thermal conductivity of various copper filler arrangements in a polymer matrix. The polymer composites are fabricated using laser cut acrylic templates to embed aligned copper rods in epoxy and create …

Spectral Phonon Relaxation Time Calculation Tool Based On Molecular Dynamics, Divya Chalise, Tianli Feng, Xiulin Ruan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Thermal conductivity is an important material property which affects the performance of a wide range of devices from thermoelectrics to nanoelectronics. Information about phonon vibration modes and phonon relaxation time gives significant insight into understanding and engineering material’s thermal conductivity. Although different theoretical models have been developed for studying phonon modes and relaxation time, extensive knowledge of lattice dynamics and molecular dynamics is required to compute phonon modal frequencies and relaxation times. Therefore, a computational tool which can take simple inputs to calculate phonon mode frequencies and relaxation time will be beneficial. Through this research work, such computational tool has …

Effect Of Aggregation And Particle Size On The Thermal Conductivity Of Nickel-Epoxy Nanocomposites, Jacob M. Faulkner, Xiangyu Li, Xiulin Ruan Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Microprocessor advancements have been stunted in recent years by inadequate means of heat dissipation as power continues to grow and size continues to shrink. One way to increase thermal conductivity while maintaining electrical insulation is to add metal nanoparticles to a polymer matrix. This cheap material has become a popular thermal interface for this reason. However, optimization of the interface is dependent upon a number of factors including particle size, shape, orientation, and aggregation. Various theoretical models and numerical approximations have been developed to find the effective thermal conductivity of such nanocomposites, but none has been able to fully incorporate …

Thermal Properties Of Soft Nanomaterials: Materials Synthesis And Fabrication, Meng Pan, Collier Miers, Amy Marconnet, Yu Han

The Summer Undergraduate Research Fellowship (SURF) Symposium

The properties of soft nanomaterials are hard to measure exactly due to their mechanical properties and unstable shape. In particular, hydrogels are a class of cross-linked polymers that can absorb large quantities of water changing their shape under the influence of various conditions such as humidity, temperature, and pH. This research addresses the fabrication of a material that has a significant contrast in properties under different conditions (e.g. temperature, wetting, and pH) and determine the physical mechanisms of heat transfer in this nanomaterial. The hydrogels are made using a several cycles of a freeze-thaw method. The method requires soluble material. …

Thermal Conductivity Of Alumina And Silica Nanofluids, Julian Bernal Castellanos

All Graduate Theses, Dissertations, and Other Capstone Projects

This thesis studies the effects of the base fluid, particle type/size, and volumetric concentration on the thermal conductivity of Alumina and Silica nanofluids. The effects of base fluid were observed by preparing samples using ethylene glycol (EG), water, and mixtures of EG/water as the base fluid and Al2O3 (10 nm) nanoparticles. The particles type/size and volumetric concentration effects were tested by preparing samples of nanofluids using Al2O3 (10nm), Al2O3 (150nm), SiO2 (15 nm), and SiO2 (80 nm) nanoparticles and ionized water as base fluid at different volumetric concentrations. All samples were mixed using a sonicator for 30 minutes and a …