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The last two decades have seen an increased interest in reducing energy consumption and carbon emissions from buildings. However, buildings and spaces are increasingly being expected to provide the best possible thermal comfort environment to the occupants. Commercial buildings are trying to adopt greener technologies in order to reduce energy consumption and provide better environment for their occupants as it makes financial sense. Residential buildings, however, are mostly owned by individuals and the adoption of greener practices is low due to the lack of knowledge by the decision makers, i.e. the homeowners. This situation can be changed by acquiring an in-depth understanding on thermal comfort in residential buildings. Currently, there are mathematical models to help predict human thermal comfort. However, will it be suitable for residential building especially in UK.

In this thesis, we study the phenomenon of thermally induced polarisation using a combination of theory and computer simulation. Molecules of sufficiently low symmetry exhibit thermo-molecular orientation when subjected to a temperature gradient, leading to considerable electrostatic fields in polar liquids. Here, we first use non-equilibrium molecular dynamics simulations to study this interesting effect numerically. To this end, we propose an integration algorithm to impose a constant heat flux in simulations and show that it greatly improves energy conservation compared to a previous algorithm. We next investigate the thermal polarisation of water and find that truncation of electrostatic interactions can lead to severe artefacts, such as the wrong sign of polarisation and an overestimation of the electric field. We further show that the quadrupole-moment contribution to the electric field is significant and responsible for an inversion of its sign. To facilitate the theoretical description of electrostatic interactions, we propose a new dipolar model fluid as a perturbation of a Stockmayer fluid. Using this modified Stockmayer model, we provide numerical evidence for the recently proposed phenomenon of thermally induced monopoles. We show that the electrostatic field generated by a pair of heated/cooled colloidal particles immersed in such a solvent can be trivially described by two Coulomb charges. Finally, we propose a mean-field theory to predict the thermo-polarisation effect exhibited by our model fluid theoretically, and demonstrate near quantitative agreement with simulation results.

The goal of this research was to determine how temperature gradients in series-connected lithium-ion battery packs affect the performance and cycle-life degradation of each of the cells in the battery pack as well as the pack as a whole. This degradation was compared to cells cycled individually and cells subjected only to calendar aging. This allowed attribution of degradation rates to specific usage conditions. Cell performance and capacity degradation was measured by utilizing standard capacity and resistance checks, neutron radiography, and other battery performance metrics. It was found that cells subjected to non-uniform temperatures within the pack degraded faster, and battery pack capacity was reduced relative to an ideal battery pack. It was also determined that the hottest cell in a series connected pack with a temperature gradient will degrade faster than an equivalent cell cycled individually at the same temperature. Despite the presence of large battery packs in modern electric vehicles, little work has been done to verify pack performance and degradation models, especially when paired with non-uniform pack temperature. This was due to the interwoven degradation stressors and mechanisms at play that need to be separately investigated to gain a full understanding of the combined effect of series packs and temperature gradients. In this work, the effects of calendar aging, cycling aging, temperature, and temperature gradients were all measured and compared. The causes of increased degradation measured on the packs with an applied temperature gradient were determined to be the superimposed effects of varying depths of discharge and non-uniform current distributions within the cells. It was also found that cell degradation did not scale linearly with applied temperature gradient. Rather, the relative rate of aging was found to follow a second order polynomial in temperature and in temperature difference. This meant that depending on the pack average temperature, the hottest or the coldest cell can degrade the most. This behavior was quantified to allow for use in optimizing the design of battery thermal management systems, and an example analysis of thermal management performance was performed on a battery pack from a Nissan Leaf.

Heat is a ubiquitous phenomenon and its spatial flow has wide reaching impact that spans industry, physiology and even meteorology through examples such as materials processing, thermotaxis and weather patterns. In fluids, spatial heat flow – temperature difference over a characteristic length scale – produces gradients in density and viscosity to generate convective currents which assuredly affects rheological properties and dynamics. The coupled effects between fluid flow and heat flow are phenomenologically explored. To achieve this, a custom-built apparatus capable of introducing, sustaining and measuring heat flux orthogonal to fluid flow was integrated into a stress-controlled rheometer to investigate the impact of steady state temperature gradients on rheological characteristics under steady shear. The novelty of this system is the capacity to independently control temperature of each rheometer plate (i.e. test surface) to establish discreet temperature gradients in the range of -16 K/mm to 30 K/mm, which also gives a window to any potential gravitational effects. Glycerol is used as a model Newtonian fluid to validate the system. Coupled dynamics is scaled by the Brinkman number and Richardson number and is found to have a linear relationship for glycerol. To expand on this knowledge, preliminary data on a more complex (non-Newtonian) system with relevance to heat transfer applications is presented. The rheological and heat flow data was presented using this approach for nanofluids of two weight fractions of Carbon Nanotubes (CNT) in glycerol in order to further understand the implications and opportunities that interrelationships between heat and fluid flow may present in a more complex system.

Thermoelectric generators (TEGs) are currently a topic of interest in the field of energy harvesting for automobiles. In applying TEGs to the outside of the exhaust tailpipe of a vehicle, the difference in temperature between the hot exhaust gases and the automobile coolant can be used to generate a small amount of electrical power to be used in the vehicle. The amount of power is anticipated to be a few hundred watts based on the temperatures expected and the properties of the materials for the TEG. This study focuses on developing efficient heat exchanger modules for the cold side of the TEG through the analysis of experimental data. The experimental set up mimics conditions that were previously used in a computational fluid dynamics (CFD) model. This model tested several different geometries of cold side sections for the heat exchanger at standard coolant and exhaust temperatures for a typical car. The test section uses the same temperatures as the CFD model, but the geometry is a 1/5th scaled down model compared to an full-size engine and was fabricated using a metal-based rapid prototyping process. The temperatures from the CFD model are validated through thermocouple measurements, which provide the distribution of the temperatures across the TEG. All of these measurements are compared to the CFD model for trends and temperatures to ensure that the model is accurate. Two cold side geometries, a baseline geometry and an impingement geometry, are compared to determine which will produce the greater temperature gradient across the TEG.

Amphibian populations worldwide are vulnerable to a variety of threats, and one serious cause of population declines and extinctions is the amphibian pathogenic fungus Batrachochytrium dendrobatidis (Bd). Amphibian species of tropical, montane regions have suffered the greatest impacts of Bd- related declines, extirpations, and extinctions. Bd is also present in temperate regions, but the effects of Bd on temperate amphibian species appear to be less severe although remain poorly understood. Bd impacts populations, species, and individuals differentially and environmental factors affect host – pathogen relationships. Temperature varies along seasonal, altitudinal, and landscape gradients and is much more variable in temperate ecosystems than in tropical montane ecosystems. I examine the relationship between amphibian hosts and the pathogen Bd in the framework of temperature along these gradients and in these ecosystems. I reviewed the literature and identified a need to support Bd temperature regimes identified by laboratory studies with research conducted among wild populations. In a temperate ecosystem, I found high rates of Bd with widespread geographic (19.5% Bd positive) and amphibian taxonomic distribution (68% of species infected) in Ohio, USA. When patterns were examined more closely among green frogs (Lithobates clamitans) and bullfrogs (L. catesbeianus), I found high rates of Bd prevalence were associated with cooler temperatures such as those experienced in springtime (89% prevalence) and stream habitats (54%). In contrast, I found high infection intensities among amphibians were associated with warmer temperatures such as those experienced in summer (8,240 ± 31,852 ZE) and emergent streams (72,645 ± 18,092 ZE). In a tropical montane ecosystem, I found that Bd is geographically widespread but persists at low prevalence (7%) among Gastrotheca pseustes tadpoles collected from mid to high elevation sites in the Ecuadorian Andes. Infected tadpoles were of poor body condition compared to their uninfected conspecifics. Bd persists in high montane environments despite cool temperatures and negatively impacts tadpole growth, but may be less virulent at mid to high elevation sites compared to low altitudes. This may provide rationale for the persistence of an endemic harlequin frog, Atelopus exiguus, that persists at 3100 masl while many harlequin frog species distributed at lower elevations have recently gone extinct. Together, these chapters provide perspective on the relationship between amphibians and the fungal pathogen, Bd and recommendations to inform future efforts in global amphibian conservation.

The goal of this research was to create a microstructure graded glass-ceramic and investigate the resulting properties as a function of crystallization processing. The desired glass-ceramic was a lithium disilicate material that has a crystallization gradient across the sample, leading to functionally graded properties as a result of the microstructure gradient. Samples were prepared by melting and pouring glass at 1400°C, annealing at 400°C for 48 hours, and nucleating at 480°C for 2 hours. To ensure that crystallization would not occur homogeneously throughout the sample, a temperature gradient was imposed during crystallization. Samples were crystallized on a self-constructed resistance wire furnace that was open to air. Several crystallization processing parameters were tested, including high temperature for a short time and low temperature for a long time. Samples were ground and polished to 0.25 microns before characterization methods were performed. Scanning electron microscopy (SEM) showed the microstructure transition across the sample cross section, with crystals present on the crystalline side and only nuclei present on the glassy side. Raman spectroscopy showed a transformation of the characteristic spectra across the sample cross section, with defined, high-intensity peaks on the crystalline side and broad, low-intensity peaks on the glassy side. Microhardness showed a slight transition in hardness values across the sample cross section, however the variability was too great to draw any conclusions. The characterization methods showed that the desired material was created and the resulting properties were a function of the crystallization processing parameters.

The Veterans’ Glass City Skyway (VGCS) is the new prestressed, post-tensioned segmental concrete cable-stay bridge that opened in June of 2007 and carries I-280 over the Maumee River. The VGCS began construction in 2001 and was monitored during most of construction by the University Research Team (URT), which includes professors and students from both The University of Cincinnati and The University of Toledo. This thesis is composed of three separate studies related to the health and monitoring of the VGCS cable stay bridge. One task was to confirm that vibrating wire strain gages installed in the bridge, as well as the rest of the data collection system, worked properly during construction when data was being collected. In order to accomplish this, a test fixture was designed and manufactured. With this test fixture the URT was able to perform a chain calibration on the entire data acquisition system and confirmed the validity of the field results. The second task involved studying temperature gradients within the concrete box girders to preliminarily assess if the VGCS response is consistent with that of the AASHTO design code. To achieve this objective, the thermistors that are attached with the vibrating wire strain gages were studied in order to confirm their reliability. It was determined that the thermistors functioned reliably and then the temperature gradients within the bridge were compared to that of the AASHTO design code, finding that the VGCS falls within the temperature design envelope. The third task consisted of designing and executing a truck test, performing the initial data reduction and assessment of the bridge response. To accomplish this goal, prior construction load tests performed on the VGCS were studied, and output from the progressively-calibrated Larsa computer model was utilized. From this task it was found that the baseline data confirms the Larsa model and that it may be used in the future to monitor the health of the bridge. While each area of interest is separated in one sense, the three tasks all relate to the structural health and long-term monitoring of the VGCS.

Sample preconcentration is a critical operation required for the determination of trace amounts of analytes of interest for which the concentration in the original solution is lower than the detection limits of the instrumentation. In this dissertation, two novel techniques, embodied in microdevices, are created that achieve large factors of preconcentration; a major advantage of these devices is the inexpensive production enabling use as simple single-use clinical devices. First, a simple PDMS device for protein preconcentration is described. The advantages of this device are its simple fabrication process and high and fast concentration. Upon application of electric fields, sample concentration is enhanced 103∼106-fold in 30 minutes at a specific location where two microchannels are positioned in close proximity to each other. Furthermore, subsequent separation of two different concentrated proteins is easily achieved. It is hypothesized that a weakly-bonded interface between PDMS and glass at the proximal point serves as a cationic selective filter by ion exclusion enrichment effect (EEE). This hypothesis is verified with supporting experiments. Second, a simple PDMS device using Temperature-Gradient Focusing (TGF) is described. This device delivers rapid and repeatable focusing of model analytes using relatively low-power compared to current TGF approaches, because Joule heating in the buffer itself generates the temperature gradient. High electric potential applied to the device induces a temperature gradient within the microfluidic channel due to the channel's variable-width, and analytes are focused at a specific location as a result of temperature-dependent species mobility. This device also shows simultaneous separation and concentration capability of a mixture of two sample analytes in less than 10 minutes. An experiment combining Joule heating with external heating/cooling further supports the hypothesis that temperature is indeed the dominant factor in achieving focusing. This thesis also describes a theoretical study that provides the governing equations depicting the electrokinetic transport phenomena along a variable-width channel supporting a temperature gradient. Those equations are then implemented into a quasi-1D multiphysics code, along with empirical data for various temperature-dependent parameters, to predict temperature distributions, analyte transport speeds, focusing locations, rates, and sample band widths. Numerical simulation results show good agreement with experimental results.

The purpose of this research has been to understand, at a fundamental level, non-equilibrium gas-phase environments for the vapor deposition of crystals and thin films. This study is based on three fundamental insights: • the existence of a chemical potential minimum in the gas phase as a function of temperature for crystal and thin film growth from the vapor; • the approximation of non-equilibrium gas phase environments by a combination of statistical mechanical states in local equilibrium (i.e. a state in chemical equilibrium at each temperature); • the construction of appropriate combinations of statistical states based on their chemical potential for some given growth conditions. Using these insights we established two ab initio non-equilibrium models describing the gas phase environments for AlN and diamond growth. Our gas phase model for AlN sublimation growth contains 62 species and 3 statistical states. The following new information regarding AlN crystal growth was obtained from the model. • AlmN (m=1,2,3,4) and Alm (m=1,2,3) species are supersaturated in the crystal layer and therefore are proposed as growth precursors; N2 is undersaturated and therefore it is not likely a precursor; • A transition temperature, Tt, was identified that characterizes growth conditions. It is the temperature at which the AlN source vaporization pressure is equal to the inlet N2 pressure. • Optimal source temperature and the total temperature difference ΔT between the source and crystal are interpreted in terms of Tt. The model can quantitatively interpret all available experiments. Our gas phase model for diamond deposition focuses on the pure hydrogen system, which we assert contains the dominant features of typical growth conditions. In the model there are H atoms and rovibrationally excited H2molecules, which together form 143 metastable statistical states. The establishment of the model consisted of three steps. ? First, a sub-model of H equal probability population was developed to calculate supersaturated hydrogen atom concentrations as the function of temperature. It assumes only those statistical states without spontaneous evolution tendency contributing to the concentration, with each of these states having an equal weight. ? Second, another sub-model of H2 maximum participation was developed to calculate the rovibrational population of H2 as the function of temperature. It assumes that only those statistical states without spontaneous evolution tendency contributing to the concentration. Each of these statistical states contributes the same as its corresponding part within the other statistical state immediately below it along chemical potential axis. ? Finally, the two sub-models are unified into one model based on the highest metastable statistical states populated. In the unified model, H2 maximum participation model is responsible for the measured gas temperatures. This unified model provides the following new insights: ? Supersaturated H atoms produced at the filament surface are stabilized in the entire gas phase due to the existence of metastable statistical states that are caused by rovibrationally excited H2. ? The overall non-equilibrium concentration of rovibrationally excited H2 is maximized due to the existence of supersaturated H atoms. ? The formation of temperature drops is related to the spontaneously chemical process. All observed ?irregular? temperature drops are further classified into four cases. ? The discrepancy among experimentally measured effective activation energies for H atom production is interpreted based on the embedded relation among filament temperature, gas-phase temperature, total pressure and concentration distributions in the unified model. ? The mechanism of acetylene conversion to methane is attributed to rovibrationally excited H2 addition chemistry due to states |v=2,J=1> ~ |v=3,J=1> of H2.