In recent years, the global nuclear industry has placed a greater emphasis on passively safe reactor designs. In particular, much attention and design work has been applied to engineered systems for passive cooling of nuclear fuel, whether it be loaded in a core or stored in spent fuel pools. The...
In the vicinity of the pseudocritical point, supercritical carbon dioxide (sCO₂) undergoes a steep change in properties from “liquid-like” to “gas-like” as it is heated at a constant pressure. At the same time, there is a large spike in specific heat which can yield high heat transfer coefficients and heat...
Boiling heat transfer is studied for its ability to dissipate high fluxes and achieve heat transfer coefficients two orders of magnitude greater than single-phase heat transfer systems. Heater surface enhancement with increased surface area, varied geometry, wettability contrast and micro/nano-structures can further enhance boiling heat transfer performance through bubble nucleation...
The metal-organic–framework MOF-5 is used as an adsorbent in advanced systems for vehicular hydrogen storage that are currently under development. Presently, these systems are limited by poor thermal conductivity of the adsorption bed, and thus our research addresses how the interfaces between grains of MOF-5 can be engineered to improve...
The Direct Reactor Auxiliary Cooling System (DRACS) is a passive safety system capable of removing decay heat directly from the reactor core. Its modularity makes it scalable for use in reactors with various power levels. Work has previously been completed to support inclusion of the DRACS in liquid metal reactors...
The purpose of this study is to measure and compare radiation emissions from flames burning large hydrocarbon fuels to assist in understanding how the molecular composition changes radiation emissions. Radiative heat transfer is significant because it is a primary mode of heat transfer for many combustion devices. This study also...
The Boltzmann transport equation derived in the Self-Adjoint Angular Flux (SAAF) formulation is applied to simulate phonon transport. The neutron transport code Rattlesnake is leveraged in this fashion, slightly modi ed to accept input from variables consistent with phonon transport simulations. Several benchmark problems are modeled to assess the potential...
The United States (US) Department of Energy (DOE) has identified the pebble-bed reactor as a high priority for US research with the end goal of licensing a pebble-bed reactor (PBR) for operation in the United States. Before this can be accomplished significant research must be done regarding the safety of...
The OSU MASLWR Test facility is a scaled integral systems LOCA and proof-of-concept test facility for the Multi-Application Small Light Water Reactor design concept. A unique feature of this design is to utilize a small high pressure containment vessel to provide the safety containment function for an integral reactor pressure...
The ever increasing requirements for heat dissipation in various thermal management applications such as computer chip cooling and high power electronics have necessitated the need for novel thermal management techniques. Thermal management using heat sinks with microscale features is amongst the prominent techniques developed over the past two decades. In...
This thesis discusses the design of several microchannel solar receiver devices for use in CSP (concentrated solar power) using CFD (computational fluid dynamics) simulations. The goal is to demonstrate that, by taking advantage of the higher heat transfer coefficienct of microchannels, solar receivers can achieve higher efficiency than current receiver...
The expansion of a gas within a piston-cylinder arrangement is studied in order to obtain a better understanding of the heat transfer which occurs during this process. While the situation of heat transfer during the expansion of a gas has received considerable attention, the process is still not very well...
The research presented in this thesis is a continuation of collaboration between Oregon State University and Auburn University studying the feasibility of passively pumping liquid during boiling in a preferential direction using meso-scaled asymmetric surface patterns. Such a passive phase-change mechanism has great potential for thermal management in spacecraft and...
The metastable isotope of technetium-99 (Tc-99m) is an important diagnostic tool used in the field of nuclear medicine due to the isotope's 6.0 hour half-life, 140.5 keV γ-decay mechanism, and multiple oxidation states [1,2]. Approximately 70% of the world’s nuclear medicine procedures involve the use of Tc-99m [3]. The conventional...
Metal oxide nanocrystals have attracted significant interests due to their unique chemical, physical, and electrical properties which depend on their size and structure. In this study, a continuous flow microreactor system was employed to synthesize metal oxide nanocrystals in aqueous solution. Assembly of nanocrystals is considered one of the most...
With continued development of the electronic industry, the demand for highly efficient heat removal solutions requires innovative cooling technologies. A computational fluid dynamic (CFD) study, including heat transfer, is performed for an axisymmetric, confined jet impingement experiencing boiling and coupled with vapor extraction. Boiling occurs at the target surface while...
At Oregon State University the Multi-Application Small Light Water Reactor (MASLWR) integral effects testing facility is being prepared for safety analysis matrix testing in support of the NuScale Power Inc. (NSP) design certification progress. The facility will be used to simulate design basis accident performance of the reactor's safety systems....
Characterization of local boiling trends, in addition to the typically reported area-averaged trends, is essential for the robust design and implementation of phase change technologies to sensitive heat transfer applications such as electronics cooling. Obtaining the values of heat fluxes corresponding to locally varying surface temperatures has been a challenge...
Advances in electronics fabrication, coupled with the demand for increased computing power, have driven the demand for innovative cooling solutions to dissipate waste heat generated by these devices. To meet future demands, research and development has focused on robust and stable two-phase heat transfer devices. A confined impinging jet is...
This thesis presents a feasibility study of a means to passively effect liquid motion parallel to a heated surface though surface geometrical modifications. Such a passive system is beneficial for electronics cooling applications as it reduces the pumping equipment normally required in flow loops and is desired for space applications,...
Droplet and spray impingement cooling are typically used in high heat flux
thermal management. In this thesis, droplet impingement and evaporation heat transfer
characteristics are determined from measured spatially- and temporally- varying fluid
and surface temperatures. Unique to this study is the documentation of the effects of
using a nanofluid...
The thermal wave technique has been explored for the use of liquid thermal conductivity measurement and flow property diagnostics in this dissertation. For liquid thermal conductivity measurements, an experimental technique based on the thermal wave approach is developed. A stainless steel strip functions as both a heating element and a...
A unique channel surface enhancement technique via diffusion-bonding a layer of conductive fine wire mesh onto the heating wall was developed and used to experimentally study flow boiling enhancement in parallel microchannels. Each channel was 1000 μm wide and 510 μm high. A dielectric working fluid, HFE 7000, was used...
A miniature reciprocating expander is being developed as part of a larger program to develop a heat actuated heat pump for portable applications. By utilizing the higher energy density of liquid hydrocarbon fuels relative to batteries, a heat actuated heat pump would be able to provide cooling for much longer...
The effect of a non-uniform magnetic field on the coupled transport of momentum and heat is studied for the case of laminar pipe flow of a magnetically susceptible ferrofluid. The momentum and heat transport equations are complemented with the necessary electromagnetic terms and used to develop a computer simulation of...
Natural convection provides a means for circulating fluids without the use of pumps. This type of system is of great interest for a wide variety of applications, including solar heaters, process industry, and nuclear reactors. Natural convection will play a vital role in the area of passive safety and reliability,...
The present study proposes to investigate the flow structure of different arrays of jets impinging on a flat surface enclosed by three walls, creating a channel that forces the air to leave in one preferential direction, generating a self sustain crossflow. Details of both the mean and some turbulence quantities...
The effects of the orifice geometry and the surface boundary condition on the heat transfer distribution to a flat surface of an impinging jet array were investigated. The jet array impinged normally onto the surface which was either isothermal or had a uniform heat flux. The experiments were performed for...
Heat transfer and fluid mechanical behavior of water
flowing horizontally in vertically-narrow rectangular
channels was studied in this work. Friction factor and
Nusselt number variations were determined experimentally
for four different wall heating conditions, and for aspect
ratios(height to width) of 5, 4, 3, 2, and 1. Wall
heating conditions...
Miniature energy and chemical systems (MECS) are miniature thermal, fluid, and chemical devices in the mesoscale size range between a sugar cube and a human fist. MECS take advantage of improved rates of mass and heat transfer that have been observed at the microscale. There are many potential applications for...
Production of surimi represents a potential utilization of a number of low-valued
fish species, one of which, Pacific whiting, represents the largest biomass off the West
Coast of the United States. However, a protease enzyme softens the fish flesh in Pacific
whiting and limits the expansion of surimi production.
Many...
Described in this thesis is an investigation of the fully developed natural convection
heat transfer in a vertical channel formed by two infinitely wide parallel plates
maintained at a uniform wall temperature. Closed-form solutions for the velocity
and temperature profiles are developed along with local and averaged Nusselt
numbers. The...
The problem of heat transfer due to free convection in a channel formed
by two parallel, isoflux, vertical plates is of considerable importance in electronic
cooling applications, thermosiphons, the optimum spacing of plates or components,
industrial stacks, heat exchangers, nuclear power plants and combustion involving
vertical walls. Although in each...
A Fabric Composite Radiation Heat Transfer Study has been
conducted to determine the effective emissivities of specific
fabric composite materials. The weave of the fabric and the
high strength capability of the individual fiber in
combination with the thermal conductivity and chemical
stability of specific metallic liner, result in a...
Convection heat transfer was experimentally investigated
for two different geometries. One case had three horizontal
cylinders in a vertical plane placed between two vertical walls.
The second case had three horizontal cylinders in a vertical plane
with only one vertical wall. Several different cylinder center-tocenter
spacings were investigated. The wall...
An experimental study is described in which time-average local heat
transfer coefficients were obtained for arrays of horizontal tubes immersed
in a hot fluidized bed. Spatial-averaged heat transfer coefficients, computed
from local values, are also reported. Refractory particles with surface
mean diameters of 2.14 mm and 3.23 mm were fluidized...
Experimental data are reported for the time-averaged
local radiative and total heat transfer coefficients for
both an array of horizontal tubes as well as a single
horizontal tube immersed in a large-particle fluidized bed
at elevated temperatures. Spatial-averaged heat transfer
coefficients computed from the local values, using a simple
trapezoidal...
Two problems relating to the processing of solid streams are
treated in two sections.
The first section is the study of heat transfer between an
immersed cylinder and a moving bed of solids: An instrumented heated
cylinder was placed in the flow stream of a moving bed of solids with...
An analytical model of the radiative contribution to the
total heat transfer between a large-particle (greater
than 1 mm) gas-fluidized bed and an immersed horizontal
tube is discussed. The model is applied to the case of a
bubbling bed and the emulsion phase contribution is obtained from a detailed analysis...
An experimental investigation has been performed to determine the
forced convection heat transfer due to three-dimensional air flow over
a flat plate as a function of angle of attack and free stream velocity.
The experimental method employed a transient thermal technique and
placed the convecting surface next to the exhaust...
In fuel pin fabrication, there is no assurance that a
fuel pellet will be loaded concentrically. Therefore,
azimuthal variations exist in the temperature field giving
rise to asymmetry in the neutron flux distribution and pin
stresses. Calculations must be made to determine the two
dimensional temperature profile which may then...
A steady gas convection model of heat transfer to a horizontal
cylinder immersed in a gas fluidized bed is presented. Contributions due to flow within
attached bubbles as well as the interstitial voids are
included. The interstitial flow is approximated as flow within a series
of double cusped channels and...
A study was conducted to determine the heat transfer characteristics
of pin finned heat sinks in natural convection. Three pin
diameters were studied: 0.238 cm, 0.318 cm and 0.396 cm. The pins
were attached to the base in two arrangements, triangular and
rectangular, forming a horizontal array. Pin spacing was...
An experimental investigation was conducted for natural convection
heat transfer in an array of uniformly heated vertical cylinders
in mercury. The test section consisted of seven electrically heated
cylinders of 1.365 inch diameter and 3.825 inch heated length
arranged in an equilateral triangular pattern. In order to preclude
side flow...