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Ett hållbart samhälle behöver ha en klimatvänlig snöröjning. Den traditionella snöröjningen är associerad med en del problem, exempelvis bidrar saltspridning till ökad korrosion av vägar och fordon, förorening av både ytvatten och grundvatten samt ökad mobilitet av tungmetaller. Ett hållbart alternativ är hydronisk markvärme, även kallat Hydronic Asphalt Pavement, HAP. Snösmältning med ett HAP-system sker genom att en varm fluid cirkulerar i rör under ytan som ska hållas snöfri. HAP- systemets energianvändning och snösmältningskapacitet är beroende av hur de värmande rören är placerade samt vilket styrsystem som används. Rapporten syftar till att öka förståelsen för hur styrsystemet och geometrin påverkar HAP-systemets energianvändning och snösmältningstid. En numerisk 2D-modell konstrueras i COMSOL Multiphysics vilken användes för att simulera styrsystemets och geometrins påverkan på HAP-systemet. Snön förenklades som en värmesänka till vilken modellen överförde värme via ett värmeflöde. En avgränsning i rapporten var att det bortsågs från vatten på ytan för att förenkla modellen. Resultatet bekräftar att HAP-systemets styrsystem och geometri har stor påverkan på dess energianvändning och snösmältningstid. Generellt ger en hög energianvändning kortare tid med snö på ytan. Det gör att om det är önskvärt att ha ett energisnålt system behöver en avvägning mellan energianvändning och tid med snö på ytan göras. Ett intermittent styrsystem bedöms vara ett bra alternativ då det ger relativt låg energianvändning och kort tid med snö på ytan. Om det inte finns en begränsning i energianvändning finns det flera styrsystem som kan ge en snöfri yta hela året. Ytans temperatur är den bästa styrparametern att använda för att minska både energianvändning och snösmältningstid. Då värmerören placeras grundare ökar energibehovet och tiden med snö på ytan minskar. Det är möjligt att placera värmerören djupare med bibehållen snöfri tid på ytan om styrsystemet anpassas efter djupet. En viktig anpassning är att styrsystemet ger en förvärmningseffekt, exempelvis att vägen börjar värmas då vägytans temperatur understiger 1°C. En ökning av avståndet mellan värmerören, CCrör, minskar energibehovet och tiden med snö på ytan ökar. Det bedöms vara möjligt att öka CCrör till 350 mm utan att generera för stora skillnader i temperaturprofilen över ytan då rördjupet är 100 mm eller 160 mm. Det styrsystem som gynnas mest av att öka CCrör till 350 mm är ”Grundfall”, vilken värmer vägen under hela vinterhalvåret. Energianvändningen minskar då med 132 kWh/m2 (22,9%) och den längsta ihållande tiden med snö på ytan ökar från 0 h till 4 h. Beroende på vad kraven på ytan är kan det vara möjligt att ha 350 mm som CCrör för de andra styrsystemen. HAP-systemet blir resurseffektivare och billigare vid konstruktion ju större CCrör som används, vilket är önskvärt. Resultatet visar att det är en liten minskning i energianvändning och snösmältningstid då isolering är under värmerören jämfört med ingen isolering. Detbedöms därför vara omotiverat ur både energisynpunkt och snösmältningsmässigt att använda isolering under värmerören på det sätt som undersökts i detta arbete. Det är en markant skillnad i energianvändning mellan ett styrsystem som är enklare och ett som är mer komplext. Om styrsystemet ”Intermittent” används i stället för ”Grundfall” vid Hamngatan i Karlstad skulle det generera en minskad energianvändning av 4,37 GWh fjärrvärme (58,5%), vilket motsvarar 199 ton CO2 per år. Resultatet understryker vikten att ett optimalt styrsystem används. Även en liten skillnad i energianvändning kan ge stora energimässiga besparingar eftersom det ofta är stora ytor som värms med ett HAP-system. För att kunna avgöra vilket styrsystem som är bäst lämpat behöver kraven på ytan bestämmas, vilket inte görs i arbetet, utan resultaten hålls generella. / A sustainable society need to have a climate friendly snow removal system. The traditional snow removal systems generate some problems, for example increased corrosion of roads and vehicles, contamination of both surface- and ground water and increased mobility of heavy metals. A sustainable alternative is Hydronic Asphalt Pavement, HAP. Snow melting with a HAP-system is generated by circulating a warm fluid in pipes underneath the surface that is to be snow free. Both the energy usage and snow melting time is affected by how the heat pipes are placed and which control system that is used. The report aims to increase the knowledge of how both the control system and geometry of the heating pipes affect the energy use and snow melting time of a HAP-system. A numerical 2D-model was constructed in COMSOL Multiphysics which was used to simulate how the control system and geometry of the heating pipes effects the HAP-system. The snow was simplified to a heat sink, to which the model could transfer heat through a convective heat flux. A demarcation of the study is that water on the surface is ignored to simplify the model. The results confirms that both the control system and geometry of the heat pipes greatly affects the energy usage and snow melting time. In general, a large energy usage generates a shorter total time with snow on the surface. It is therefore needed to do a balancing between energy usage and the total time with snow on the surface if the energy usage is to be restricted. An intermittent control system is considered to be a good alternative as it gives a relative low energy usage and short time with snow on the surface. If there is no limitation on the energy use, there is several control systems that gives a snow free surface throughout the year. The surface temperature is the best parameter for the control system as it minimizes both the energy usage and snow melting time. When the heating pipes is placed shallower the energy usage is increased and the time with snow on the surface decreases. It is possible to place the heating pipes at a greater depth and still have the same functionality of the HAP-system if the control system is adjusted accordingly. One important adjustment for the control system is preheating, for example that the heating is turned on when the air temperature is less than 1°C. An increase of CCrör decrease the energy usage and increase the time with snow on the surface. It is possible to increase CCrör to 350 mm and still have a smooth temperature profile if the heating pipes is placed 100 mm or 160 mm beneath the road surface. The control system that gains the most out of an increase in !!!ö! to 350 mm is “Grundfall”, which reduce its energy usage with 132 kWh/m2 (22,9%) and the longest time with snow on the surface is increased from 0 h to 4 h. Depending on which demands the surface is to meet, it is possible to have 350 mm as CCrör for the other control systems. An increase in CCrör makes the HAP-system more resource efficient and cheaper to build, which is desirable. The results show a small decrease in energy usage and snow melting time when isolation is underneath the heating pipes compared to without isolation. It is therefore deemed to be unmotivated to use isolation as it is used in this paper, in both energy use- and snow melting time-perspective. There is a significant difference in energy use between a simple and more complex control system. If the control system “Intermittent” is used instead of “Grundfall” at Hamngatan in Karlstad the energy usage would decrease with 4,37 GWh heat (58,5%) and 199 ton of CO2. The result underlines the importance of an optimal control system for a HAP-system. Even a small change in energy consumption can generate large energy savings due to the scale of the surfaces that is heated with HAP-systems. To be able to decide which control system that is the best suited, the demand on the surface needs to be set. The demands are not set in this paper in order to keep the results general.

Jet noise has been a growing concern in recent years due to the costs associated with hearing loss of United States service members. Jet noise is also becoming more of a concern due to the rise of civilian complaints regarding the noise of jets near civilian and military air stations. One source of noise generation is from packets of air called eddies, which move with a convection velocity Uc. The current work seeks to expand upon the understanding of jet noise by collecting data using Time-resolved Doppler global velocimetry (TR-DGV) from regions of the jet known to produce high levels of acoustic radiation. Past experiments in studying convection velocity are reviewed based on the technique for obtaining the velocities. To add to these experiments, the current work analyzes data obtained using TR-DGV applied to a perfectly expanded Mach 1.65 flow with total temperature ratio (TTR) equal to 1. Additional measurements were obtained on a Mach 1.5 nozzle operated at a slightly over expanded condition and at TTR = 2. The cold jet flow is compared to the past experiments on unheated jets and demonstrates good agreement with respect to normalized convection velocities based on the jet exit speed. The data is then compared to past experiments conducted on the same nozzle at heated conditions. Shadowgraph imaging is used as a qualitative tool to locate shock cells within the jet plume. TR-DGV data from near the lipline (r = 0.5D) is axially aligned with the shadowgraph images to demonstrate that the shock structure within the potential core causes detectable variations in the scalar convective velocity. Additionally, it is shown that in the heated and unheated Mach 1.65 jet and the over expanded heated Mach 1.48 jet that the convection velocity does increase beyond the potential core. The Mach 1.48 jet is also compared to mean velocities obtained using Particle Image Velocimetry and found that the convective and mean velocities were only similar in some regions of the jet. A discussion is provided on suggestions of future work on where to obtain data within the jet plume and how to collect the data using current capabilities. Suggestions are also provided for improving data quality in future experiments, as well as ideas for future investigations into convection velocity along the length of the jet plume using TR-DGV. / Master of Science / Jet noise has been a growing concern in recent year due to the costs associated with hearing loss of United States service members. Additionally, many civilians complain about the noise of aircraft flying both out of military facilities and commercial airports. One source of noise generation is from packets of air called eddies which move with a convection velocity. Researchers have identified that by affecting the convection velocities of these eddies, there is a larger benefit than other traditional methods such as engine chevrons. The current work summarizes techniques used to investigate convective velocity as well as to provide evidence for other unconfirmed theories. This study focuses on using a laser-based technique to obtain data within the flow of an unheated supersonic jet. An unheated jet is studied to allow for easy comparison to other experiments that have used different diagnostic techniques. Additionally, this case is studied to complete a set of experiments that were previously conducted on the same nozzle so that there is a true base-line or “control” case for future work. Later in this paper, analysis will be done to show how shocks within the jet affect the convective velocity. A combination of both quantitative and qualitative efforts are performed to accomplish this. Additionally, it will be shown that after the potential core of the jet breaks down, there is an increase in the local convective velocity in this region immediately after the potential core. Finally, a brief summary will be given and suggestions for future work will be presented.

[pt] A presente tese tem por objetivo o estudo teórico e experimental, seguindo as boas práticas metrológicas, de um método baseado em uma fonte esférica de calor para medição da condutividade térmica de líquidos, com foco em soluções aquosas de etanol, e posterior determinação do teor de água da substância. O estudo e o desenvolvimento de métodos de medição de condutividade térmica são essenciais em diversas aplicações de engenharia, visto que, em consequência das justificadas demandas atuais de economia e uso racional de energia térmica, a transferência de calor com a máxima eficiência possível é de extrema relevância. A medição do teor de água também é um relevante parâmetro em muitas áreas de pesquisa e nos setores industriais, pois a quantidade de água nas substâncias influencia vários processos físicos, químicos e biológicos. Contudo, a quantidade de equipamentos disponíveis no mercado para a medição de ambas as grandezas não é vasta. O método da esfera quente, em principio, é um método absoluto de medição da condutividade térmica, o que significa que o sensor pode fornecer um resultado sem ser calibrado. Porém, alguns parâmetros do modelo precisam ser analisados isoladamente ou obtidos por meio de calibração. Embora haja alguns estudos sobre este método, poucos têm os meios líquidos como foco principal. Ademais, tais estudos não correlacionam a condutividade térmica do material com o seu teor de água e nem realizam uma análise metrológica mais criteriosa, de modo a determinar minuciosamente as incertezas de medição. A aplicabilidade do método para medição da condutividade térmica e do teor de água das soluções analisadas mostrou-se bastante satisfatória, pois os resultados obtidos neste estudo apresentaram muito boa concordância com os valores propostos por vários pesquisadores e com as medições realizadas no Inmetro por outros métodos. / [en] The aim of this thesis is the experimental and theoretical study, following the good metrological practices, of a method based on a spherical heat source in order to measure thermal conductivity of liquids, focusing on aqueous solutions of ethanol, with later determination of the water content of the substance. The study and the development of measuring methods of thermal conductivity are essentials in several engineering applications, since as a consequence of the current justified demands on saving and rational use of thermal energy, the heat transfer with the maximum efficient as possible is of great relevance. The measurement of the water content is also a relevant parameter in several research areas and industrial sectors, since the quantity of water in the substances influences several biological, chemical and physical processes. However, the amount of equipment available on the market for the measurement of both quantities is not vast. The heated sphere method, in principle, is an absolute one for the measurement of the thermal conductivity, which means that the sensor may furnish a result without a calibration. Nevertheless, some parameters of the model need to be analyzed separately or obtained by means of calibration. Although there are some studies on this method, few of them have liquids as the main focus. Moreover, these studies do not correlate the thermal conductivity of the material with its water content, and they do not perform a more careful metrological analysis in order to determine the measurement uncertainties. The applicability of the method to measure the thermal conductivity and the water content of the analyzed substances proved to be satisfactory, because the obtained results of this study presented a very good agreement with the values proposed by several researches and with the measurements performed at Inmetro by other methods.

This dissertation aims to advance the current state of use of silicon atomic force microscope (AFM) cantilevers with integrated heaters. To this end, the research consists of two primary thrusts - demonstrating new applications for the cantilevers, and advancing the current state of understanding of their thermal and mechanical behavior to enable further applications. Among new applications, two are described. In the first application, the cantilevers are used for nanoscale material deposition, using heat to modulate the delivery of material from the nanoscale tip. In the second application, the cantilever performs thermal analysis with nanoscale spatial resolution, enabling thermal characterization of near surface and composite interphase regions that cannot be measured with bulk analysis techniques. The second thrust of the research seeks to address fundamental questions concerning the precision use of heated cantilevers. Efforts to this end include characterizing the mechanical, electrical, and thermal behavior of the cantilevers, and optimizing calibration methodology. A technique is developed for calibrating the cantilever spring constant while operating at elevated temperature. Finally, an analytical model is developed for the heat flow in the cantilever tip and relevant dimensionless numbers that govern the relative importance of the various components of the thermal environment are identified. The dimensionless numbers permit exploration of the sensitivity of the tip-substrate interface temperature to the environmental conditions.

This work describes two closed-loop atomic force microscopy methods that utilize the heated silicon probe to interrogate surfaces. The first method identifies the softening temperatures of a selected polymer and organic substrate as a function of contact force and surface hardness. Motivation partly stems from nanosampling, which requires knowledge of phase-specific transitions to identify and extract mass from multicomponent systems for chemical analysis. In the second method, the cantilever is implemented as a Kelvin probe to study the effect of temperature on the measured contact potential. The objective is to ascertain whether the probe functions as a capable electrode for scanning Kelvin probe microscopy (SKPM) applications. This was achieved by performing heated force-distance experiments on a biased gold film with the tip operating at various potentials. Both experiments examine the interaction between the tip and substrate and analyze sample effects both induced and sensed by the cantilever.

¡@¡@We integrated the laser-heated pedestal growth (LHPG) system with accurately controlled electrodes to build up our in situ poling system. The ZnO and MgO doped periodically poled lithium niobate crystal fiber were fabricated with the poling system. This poling system has the advantage of convenience and fast growth, but the ¡§screen effect¡¨ caused by free charges which exist near the molten zone must be eliminated. The micro swing resulted from the electric force is a feasible solution, because it can disarrange the free charges and reduce the ¡§screen effect¡¨. However, without excellently controlled micro swing, the uniformity of the poled domain pitch will loose and the conversion efficiency can not be improved. After analysis of the measured current data, the approximate system current model was presented and the proportional dependence between system current and micro swing was verified. Thus the system current was applied as the micro swing feedback signal, with that the variation of the micro swing was reduced from 25% to 15%. The stability of CO2 laser power is also a dominant factor to determine the quality of poled crystal fiber. The variation of the CO2 laser power was controlled within 1%. All the complicated works and precise control during the crystal fiber growth were accomplished with the LabVIEW program. ¡@¡@A novel and simple self-cascaded SHG + SFG scheme is presented for the generation of tunable blue/green light using ZnO doped periodically poled lithium niobate crystal fiber (PPLNCF) with a single designed pitch. A PPLNCF with a uniform period of 15.45£gm, the maximum conversion efficiency for the second harmonic generation and the cascaded SHG + SFG blue light can reach up to -9.2 dB and -31.9 dB, respectively. The 3 dB bandwidth of the tunable blue light is 3 nm (475-478 nm). In order to expand the tuning bandwidth range, a QPM gradient periodical structure was designed and can provide a 3 dB bandwidth of 65 nm for the tunable blue/green light output by simulation. We have successfully grown a crystal fiber with the domain pitch of 18.9 £gm for the C-band wavelength converter. The crystal length is 1.8 mm, the effective nonlinear coefficient of the lithium niobate crystal fiber is 18.2 pm/V that equals 0.53¡Ñdideal (34.4 pm/V). The conversion efficiency for converting the CW laser in C-band is about -59.3 dB.

Natural convective heat transfer from flat plates and short cylinders inclined at an angle to the vertical in laminar and transition flow regions with isothermal or constant heat flux conditions have been numerically and experimentally studied. When the width of the plate is relatively small compared to its height, i.e., the plate is narrow, the heat transfer rate can be considerably greater than that predicted by these two-dimensional flow results. When the narrow plate is inclined to the vertical, pressure changes normal to the plate surface arise and these pressure changes can alter the nature and the magnitude of the edge effects. When two narrow inclined rectangular flat plates of the same size separated vertically or horizontally, the flow interaction between these heated plates can have a significant effect on the heat transfer. When relatively small square and circular cylinders with exposed top surfaces inclined to the vertical are used, the interaction of the flow over the surfaces that make up the cylinder and inclination angle have, in general, a considerable effect on the magnitude of the mean heat transfer rate and on the nature of the flow over the cylinder surfaces. In the present numerical studies it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces, this having been treated using the Boussinesq approach. The numerical solution was obtained by numerically solving the full three-dimensional form of the governing equations, these equations being written in dimensionless form. The solution was obtained using a commercial CFD code, FLUENT. Results were only obtained for a Prandtl number of 0.7; this being approximately the value of air. In the experimental studies, the average heat transfer rates from cylinders were determined by the transient method, which involves heating the model and then measuring its temperature-time variation while it cools. The average heat transfer rates from the flat plates were determined using a steady state method, which basically involved electrically heating the plate. The tests were carried out inside a large enclosure. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2011-06-27 19:27:45.724

An evaporating meniscus formed by a wetting °uid in a heated capillary slot with capillary driven °flow is numerically and experimentally investigated at the microscale and pore scale. In the microscale analysis, the contact line region of an extended evaporating thin ¯lm meniscus is numerically investigated to study the influence of °uid properties on the heat transfer. The governing equations to describe the fluid °flow, heat and mass transfer phenomena in an evaporating extended meniscus are grouped uniquely as function of °uid dependent parameters, namely the interline heat flow number and heat pipe ¯figure of merit. A physical interpretation of these parameters is presented. Numerical experiments conducted with different working °fluids show that a °uid with a high interline heat °flow parameter and heat pipe ¯figure of merit also has a high cumulative heat transfer in the micro region encompassing the evaporating thin ¯lm. In the pore scale analysis, the evaporation from a pentane meniscus in a heated capillary slot is experimentally and numerically investigated to study how the wetting characteristics are influenced with heat input. In the experimental investigation, a test set up is fabricated with a heated glass capillary slot that is partially immersed in a constant temperature bath with constant °uid level. A novel aspect of this experiment is that both the wicking height and steady state evaporation mass flow rate are measured simultaneously. Based on a macroscopic force balance, the apparent contact angle of the evaporating meniscus is experimentally estimated from the wicking height and mass flow rate. This is compared with the results obtained using evaporating thin ¯lm theory. The experimentally estimated contact angle is higher than that obtained from the thin ¯lm model but both experiment and theory show similar trends. In the numerical study, a ¯finite volume numerical model of an evaporating meniscus in a heated capillary slot (simulating the above experimental condition) is developed for predicting the wicking height and mass flow rate. This model includes: (i) one-dimensional heat transfer and °uid °flow in the liquid and vapour regions of the capillary slot, (ii) one{dimensional evaporating thin ¯lm model for the meniscus region, and (iii) two-dimensional conduction heat transfer in the capillary wall. Correlations obtained from the evaporating thin{¯lm theory in terms of cumulative heat transfer and apparent contact angle are applied to the pore level problem. The problem is solved iteratively between the micro and pore scales till convergence is achieved. The wicking height is influenced by the change in apparent contact angle and the pressure drops to flow of liquid and vapor in the capillary slot that is a function of evaporation mass °ow rate. Heat input to the capillary slot increases both the contact angle in the evaporating meniscus and the frictional pressure drops in the liquid and vapor regions. In the present study, the influence of increased contact angle is more significant and the liquid and vapor pressure drops are negligible. The trends in the wicking height, mass flow rate and conductance are similar to the experimental data. The proposed numerical approach using correlations from thin ¯lm theory to link the micro and macro scales yields results that are consistent with experimental data. The results show that the change in contact angle can degrade the ability of the liquid to wet the pore and hence result in a lower heat transfer coefficident.