High Voltage Direct Current (HVDC) bushings are insulated devices designed to facilitate the safe passage of electric current across an earthed barrier. Understanding air conductivity is of utmost importance in the design of HVDC components, which is determined by ion density and ion mobility. Previous research has indicated a correlation between air conductivity, air humidity and phenomena on HVDC surfaces. This thesis aims to investigate and elucidate how adsorbed water may contribute to air conductivity. To accomplish this objective, an experimental study is conducted employing ellipsometry to measure the water layer thickness as a function of relative humidity and applied voltage. The results exhibit a thickness consistent with prior studies in the absence of applied voltage, but reveal an altered thickness when voltage is applied. While definitive conclusions cannot be drawn from this thesis alone, the findings provide some support for the hypothesis from earlier research, suggesting the involvement of surface phenomena in air conductivity. The experimental procedure presented in this thesis can be further expanded and refined to gain a more comprehensive understanding of the surface reactions at play. This could further develop the understanding of the factors influencing air conductivity in HVDC systems and contribute to the advancement of design methodologies in this field.

Maintaining performance and mitigating heat stress of the modern broiler is a challenging task during hot weather conditions. Increased demand of high quality reasonably priced animal protein and predictions of future limited water availability make sustainability and water conservation a worthwhile goal for the poultry industry. The most used form for cooling broilers after wind speed is evaporative cool cell (CC) systems. Though highly effective at cooling the incoming air, they substantially increase the relative humidity inside the house, which hinders the bird’s ability to cool itself through evaporative respiration. Cool cells also utilize mass amounts of water. The objective of this research was to evaluate the effects of sprinkler technology on broiler performance, cooling water usage, inhouse environments, conservation, and sustainability, while providing information on how to successfully utilize sprinkler cooling in conjunction with an evaporative cool cell system.

Background: Most over-the-counter medications are labeled for storage in a dry, room temperature environment. Despite this, many households store medications in the bathroom, where temperature and humidity extremes may be experienced.Objective:In this project, we sought to investigate the effect that long-term storage in a household bathroom had on potency of over-the-counter ibuprofen (IBU) products as well as on the emergence of a known toxic degradation product, 4-isobutylacetophenone (4-IBP). Methods:A liquid chromatography-tandem mass spectrometry method was developed for the quantitative determination of IBU and 4-IBP in aqueous samples. Three brands each of IBU tablets (200 mg) and suspensions (100 mg/5 mL) were assayed for IBU concentration at the initiation of the study and once monthly thereafter. The samples were stored in a household bathroom, with continuous temperature and humidity monitoring. Each sample was assayed in triplicate and percent recovery was calculated against freshly prepared standards of IBU using bulk powder.Results:Tablets maintained >90% average strength through 3 months, with statistically significant deviation from initial concentration (2-way analysis of variance, P = .05) detected after 6 to 7 months. Suspensions maintained >90% average strength through 5 months, with statistically significant changes from initial concentration emerging after 7 months. After 12 months, the average strength was 73% and 83% for tablets and suspensions, respectively. 4-IBP was not detected in any of the samples during the duration of the study.Conclusions:These data indicate that, while 4-IBP was not detected following 12-month bathroom storage of commercial IBU products, significant changes in potency should negatively affect efficacy.

Electrostatic charge generation in gas-solid fluidized beds is a significant industrial problem. Associated problems include particle agglomeration and particle wall fouling. In the polymerization industry this may result in "sheets" of fused polymer, due to exothermic reaction causing the melting of the polymer, which can fall off and block the distributor plate disrupting fluidizing gas flow. Additionally, blockage of the catalyst feed or the polymer removal system can take place or the product can become non-uniform. All of these problems require shut-down of the reactor which results in lost production time. While this phenomena has been identified for many years, the mechanisms involved are not well understood, especially wall fouling and the distribution of charge within the bed. Isolation of individual parameters such as hydrodynamics, operating conditions, and material involved is necessary to evaluate how each parameter impacts charge generation during fluidization. In this thesis, the fluidization system consisted of a stainless steel column, two online Faraday cups, and a retractable distributor plate. This system allowed for the simultaneous measurement of charge within different regions of the bed: the entrained fine particles, the particles adhered to the column wall, and the bulk of the bed. Additionally, mass and particle size distributions were measured and images of the layer of particles adhered to the column wall were taken for comparison. This allowed for a charge distribution comparison and evaluation of wall fouling. Three different parameters were investigated: duration of fluidization, column wall material, and relative humidity of fluidizing gas. Fluidization time was studied for 15, 30, 60, 120, 180, and 360 min; relative humidity was investigated for 0%, 20%, 40%, 60%, and 80% relative humidity. Both fluidization time and relative humidity were evaluated at four different fluidization gas velocities, two each in the bubbling and slugging flow regimes. Column wall material was evaluated for a stainless steel and carbon steel column at two gas velocities, one each in the bubbling and slugging flow regimes. Fluidization time was found to influence wall fouling in the bubbling flow regime as the particle layer continued to build as fluidization progressed. In the slugging flow regime, the particle layer developed within 15 minutes of the onset of fluidization. The bubbling flow regime was shown to have a greater capacity for charge generation than the slugging flow regime. This was due to the vigorous mixing in the bubbling flow regime resulting in more particle-particle interactions. Column wall material was shown to influence wall fouling in the slugging flow regime due to the differences in surface roughness of the columns. This was due to the particle-wall contacts resulting in frictional charging which is the predominant charging mechanism in this flow regime. Charge was also impacted in the bubbling flow regime in those particles that were adhered to the column wall. Relative humidity was found to influence wall fouling at the lowest gas velocity tested. However, variations in generation of charge occurred at all fluidization gas velocities tested; the charge-to-mass ratios for the particles adhered to the column wall in the slugging flow regime decreased with high relative humidities. This was due to either the formation of a water film layer on the column wall or instantaneous surface water films on the particles throughout fluidization.

In the Peruvian Andes, inadequate housing represents an important problem for the local rural people. Over 3000 meters above sea level, communities suffer from very low indoor temperatures this becomes an issue which affects the health and indoor thermal comfort of the building. At early winter mornings, outdoor temperatures can occasionally go down to -15°C and indoor temperatures can drop below zero. Previous work in the field has been done by the Pontifical Catholic University of Peru PUCP, to address thermal comfort in Langui, Peru involving participatory design techniques, multidisciplinary approaches and a focus on sustainability. Their most recent design is based on an attached passive solar heating system similar to a Trombe wall. The effect of housing environment on human health has been an acknowledged issue for many years. In the area, the occupants live with high levels of air infiltration, dirt floor (soil), simple windows, metallic or wood doors, roof most commonly made of corrugated metal sheets, adobe walls, no additional insulation attached and no house heating system. This thesis aims to contribute to a current body of research on thermal comfort and provide insights on how the building environment in Langui can be improved. The main objective is to improve thermal comfort in residential buildings in Andean regions of Peru. An improvement was made by installing a Heat Transfer Rocket which increased the temperature while the relative-humidity stayed steady. Overall, the study shows that indoor improvements can increase thermal comfort in Andean regions of Peru.

The majority of therapeutic pharmaceutical formulations are presented in the solid form. Moisture is able to play an important role in the functional performance of pharmaceutical solids. Moisture profiling is able to provide novel information with regards to the behaviour of moisture within materials using equilibrium relative humidity as a measurement. The hypothesis investigated explores the changes in equilibrium relative humidity of pharmaceutical material induced by physical, chemical or storage conditions, these are able to be monitored using the innovative moisture profiler system. The aims within this were to primarily validate the moisture profiler and secondly evaluate the effects of moisture on physical forms and with respect to effects of compaction, finally this was compared to conventional characterisation methods. Preliminary explorations were conducted in order to assess the validity of the moisture profiler, from this lactose was selected as a suitable pharmaceutical material for further work. Processing effects were then examined, firstly storage at elevated relative humidity of different forms of lactose were explored, and this was carried out with supplementary analysis. Secondly the effects of tabletting were explored, different compaction forces were investigated to observe if this had any notable effects on equilibrium relative humidity of the different lactose forms. Finally subsequent storage of the compacts were examined in order to explore if there were any changes in the equilibrium relative humidity. / EPSRC and Reckitt Benckiser

Current sealant test methods do not lend themselves well to the measurement and prediction of sealant performance. T he objective of this work was to demonstrate that measurement of sealant material properties as a function of temperature and relative humidity for a specific sealant and substrate can be used to predict the long term performance of sealant joints independent of the joint geometry. The material properties of a silicone sealant were characterized as a function of temperature, relative humidity and test rate. The fracture energy of the silicone sealant bonded to glass, aluminum or stainless steel was measured with the 180° peel, the 45° peel and the pure shear butt joint test methods. Scanning electron microscopy, electron spectroscopy for chemical analysis and atomic force microscopy were used to analyze the failure surfaces. The failure mode for silicone sealant on aluminum changes from near the aluminum oxide layer to cohesive in the sealant when the relative humidity is less than 35%. The temperature shift factor was not related to the WLF theory but worked well with an Arrhenius theory. The activation energy for the fracture process was 31.2 kcal/mol. Crack growth data for an expansion joint was calculated for the weather conditions in Miami, Florida and Wittman, Arizona using the climate data obtained for the year 1994. For both climates, the nearly all the crack growth occurred during the winter months. The predicted annual crack growth data for Miami was 0.7 mm and the predicted annual crack growth for Wittman was 3.7 mm. The fracture energy of the silicone/stainless steel joint is proportional to the amount of PDMS left on the surface. Carbonaceous contamination is not displaced by the sealant. Contamination inhibits primary bonding (ionic or covalent) and results in a lower fracture energy. Roughness increases the fracture energy; and this effect is more pronounced when the surfaces are cleaner. Water lowers the fracture energy especially for the dirtier surfaces. Roughness reduces the effect of the water damage but doesn’t eliminate it. / Ph. D.

The continued focus to include high hydrogen fuels such as Syngas in aircraft operation to reduce emissions and increase engine efficiency has led to an ongoing investigation into bond coat materials capable of withstanding unfavourable oxidation in high temperature humid environments. The increased presence of water in the engine exhaust leads to increased oxygen activity in the hot section of the engine. In this work, four commercially available MCrAlY bond coat materials were oxidized in high temperature environments with various humidities to understand the behaviours of different reactive element inclusions in resisting high temperature oxidation. Oxidation tests were done at 0%, 18%, and 33% water by volume at 1100C in a 1atm environment to simulate conditions expected in engines using high hydrogen fuels. Oxidation was done for 2h and 20h to observe transient oxide formation behaviour. The surfaces and cross sections of the specimens were examined using SEM and EDS analysis, along with XRD analysis. The progression of surface oxides, TGO thickness, and element depletion zones were observed. Two opposing mechanisms are observed: the upward diffusion of metal cations to the free surface and the inward diffusion of oxygen to the alloy. The presence of water is shown to increase internal oxidation of the bond coat alloy and delay the formation of a protective alumina TGO. Tantalum inclusion in the alloy composition is shown to produce the most stable alumina TGO with the least internal oxidation after 20h exposure in 33% H2O (%vol); the most hostile oxidation environment tested.

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