"Asphalt pavements are made up of several layers of materials and different types of materials are being used as base courses in these pavements. The properties of these pavement layers are affected significantly by temperature, and all of the layers are made up of heterogeneous mixtures of a wide variety of materials whose thermal properties are not readily available. Therefore, laboratory experiments were carried out with samples of pavements with different base course materials to determine temperature profiles along the depth, and finite element analysis was used to backcalculate thermal properties of the materials in the different layers of the different samples. The concept of extracting heat energy from asphalt pavements was evaluated by finite element modelling and testing small and large scale asphalt pavement samples. Water flowing through copper tubes inserted within asphalt pavements samples were used as heat exchangers in the experiments. The rise in temperature of water as a result of flow through the asphalt pavement was used as the indicator of efficiency of heat capture. The results of small scale testing show that the use of aggregates with high conductivity can significantly enhance the efficiency of heat capture. The efficiency can also be improved by using a reflectivity reducing and absorptivity increasing top layer over the pavement. Tests carried out with large scale slabs show that a larger surface area results in a higher amount of heat capture, and that the depth of heat exchanger is critical Heat-Islands are formed as a result of construction that replaces vegetation with absorptive surfaces (asphalt pavement). One suggested method to reduce the emitted heat from asphalt pavement surfaces is to reduce the temperature of the surface by flowing a suitable fluid through the pavement. Laboratory experiments were carried out using hand-compacted hot mix asphalt samples with quartzite and metagranodiorite aggregates. Pipes with different surface area were used to flow water through the samples, and the processes were modeled using finite element method. The results clearly show the feasibility of the proposed method, and indicate the beneficial effects of higher thermal conductivity of aggregates and larger surface area of pipes. "

Typescript (photocopy). / Digitized by Kansas Correctional Industries / Department: Electrical and Computer Engineering.

Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / Microfiche copy available in Archives and Science. / Bibliography: leaves 225-237. / Sc.D.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Vita. / Bibliography: leaves 76-78. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1983. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH / Includes bibliographical references (p. 69-70). / A prototype for a dwelling heat loss compensator is introduced in this thesis, along with its measured thermal performance and suggestions for its future development. As a heat loss compensator, the Sol-Clad-Siding collects, stores, and releases solar heat at room temperatures thereby maintaining a neutral skin for structures, which conserves energy, rather than attempting to supply heat into the interior as most solar systems do. Inhabitants' conventional objections to passive-solar systems utilized in housing are presented as a contrasting background. The potential of the outer component, a Trans-Lucent-Insulation as a sunlight diffuser and transmitter (65 to 52% of heating season insulation) and as a good insulator [0.62 W/(sq m) (°K) [0.11 Btu/(hr) (sq ft) (°F) 1] are described. The performance of the inner component, a container of phase-change materials as an efficient vertical thermal storage is discussed, and areas for future research are addressed. A very brief application of this passive-solar curtain wall system for dwellings is also given. / by Doru Iliesiu. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Vita. / Includes bibliographical references. / by Ronald James Salig. / M.S.

Melting and solidification constitute the fundamental pathways through which a thin-film material is processed in many beam-induced crystallization methods. In this thesis, we investigate and leverage a specific beam-induced, melt-mediated crystallization approach, referred to as Mixed-Phase Solidification (MPS), to examine and scrutinize how a polycrystalline Si film undergoes the process of melting and solidification. On the one hand, we develop a more general understanding as to how such transformations can transpire in polycrystalline films. On the other hand, by investigating how the microstructure evolution is affected by the thermodynamic properties of the system, we experimentally reveal, by examining the solidified microstructure, fundamental information about such properties (i.e., the anisotropy in interfacial free energy). Specifically, the thesis consists of two primary parts: (1) conducting a thorough and extensive investigation of the MPS process itself, which includes a detailed characterization and analysis of the microstructure evolution of the film as it undergoes MPS cycles, along with additional development and refinement of a previously proposed thermodynamic model to describe the MPS melting-and-solidification process; and (2) performing MPS-based experiments that were systematically designed to reveal more information on the anisotropic nature of Si-SiO₂ interfacial energy (i.e., σ_{Si-SiO₂}). MPS is a recently developed radiative-beam-based crystallization technique capable of generating Si films with a combination of several sought-after microstructural characteristics. It was conceived, developed, and characterized within our laser crystallization laboratory at Columbia University. A preliminary thermodynamic model was also previously proposed to describe the overall melting and solidification behavior of a polycrystalline Si film during an MPS cycle, wherein the grain-orientation-dependent solid-liquid interface velocity is identified as being the key parameter responsible for inducing the observed microstructure evolution. The present thesis builds on the abovementioned body of work on MPS. To this end, we note that the limited scope of previous investigations motivates us to perform more thorough characterization and analysis of the experimental results. Also, we endeavor to provide more involved explanations and expressions to account for the observed microstructure evolution in terms of the proposed thermodynamic model. To accomplish these tasks forms the motivation for the first portion of this thesis. In this section we further develop the thermodynamic model by refining the expression for the solid-liquid interface velocities. In addition, we develop an expression for the grain-boundary-location-displacement distance in an MPS cycle. This is a key fundamental quantity that effectively captures the essence of the microstructure evolution resulting from MPS processing. Experimentally, we conduct a thorough investigation of the MPS process by focusing on examining the details of the microstructure evolution of {100}-surface-oriented grains. Firstly, we examine and analyze the gradual evolution in the microstructure of polycrystalline Si films being exposed to multiple MPS cycles. A Johnson-Mehl-Avrami-Kolmogorov-type (JMAK-type) analysis is proposed and developed to describe the microstructure transformation. Secondly, we investigate the behavior of grains with surface orientations close to the <100> pole. Orientation-dependent (in terms of their extent of deviation from the <100> pole) microstructure evolution is revealed. This observation indicates that the microstructure of the film continues to evolve to form an even tighter distribution of grains around the <100> pole as the MPS process proceeds. During MPS melting-and-solidification cycles, a unique near-equilibrium environment is created and stabilized by radiative beam heating. Therefore, the microstructure of the resulting films is expected to be explicitly and dominantly affected by various thermodynamic properties of the system. Specifically, we identify the orientation-dependent value of the Si-SiO₂ interfacial energy as a key factor. This being the case, the MPS method actually provides us with an ideal platform to experimentally study the Si-SiO₂ interfacial energy. In the second part of this thesis, we perform MPS-based experiments to systematically investigate the orientation-dependent Si-SiO₂ interfacial energy. Two complementary approaches are designed and conducted, both of which are built on examining the texture evolution of different surface orientations resulting from MPS melting-and-solidification cycles. The first approach, “Large-Area Statistical Analysis”, statistically examines the overall microstructure evolution of non-{100}-surface-oriented grains. By interpreting the changes in the surface-orientation distribution of the grains in terms of the thermodynamic model, we identify the orientation-dependent hierarchical order of Si-SiO₂ interfacial energies. The second approach, “Same-Area Local Analysis”, keeps track of the same set of grains that undergo several MPS cycles. An equivalent set of information on the Si-SiO₂ interfacial energy is extracted. Both methods reveal, in a consistent manner, an essentially identical Si-SiO₂ interfacial energy hierarchical order for a selected group of orientations. Also, the “Same-Area Local Analysis” provides some additional information that cannot otherwise be obtained (such as information about the evolution of two adjacent grains of specific orientations). Using such information and based on the grain-boundary-location-displacement distance derived using the thermodynamic model, we further deduce and evaluate the magnitude of Δσ_{Si-SiO₂} for certain orientation pairs.

Dissimilar metal joining was performed with the main goal being maximization of the strength of the joined samples, but because of some potential applications of the dissimilar joints, analyzing their corrosion behavior also becomes crucial. Starting with materials that initially have suitable corrosion resistance, ensuring that the laser processing does not diminish this property is necessary. Conversely, the laser shock peening processing was implemented with a complete focus on improving the corrosion behavior of the workpiece. Thus, many commonalities occur between these two manufacturing processes, and this thesis goes on to analyze the thermal and mechanical influence of laser processing on materials’ corrosion resistances. Brittle intermetallic phases can form at the interfaces of dissimilar metal joints. A process called autogenous laser brazing has been explored as a method to minimize the brittle intermetallic formation and therefore increase the fracture strength of joints. In particular, joining of nickel titanium to stainless steel wires is performed with a cup/cone interfacial geometry. This geometry provides beneficial mechanical effects at the interface to increase the fracture strength and also enables high-speed rotation of the wires during irradiation, providing temperature uniformity throughout the depth of the wires. Energy dispersive X-ray spectroscopy, tensile testing, and a numerical thermal modelling are used for the analysis. The material pair of nickel titanium and stainless steel have many applications in implantable medical devices, owing to nickel titanium’s special properties of shape memory and superelasticity. In order for an implantable medical device to be used in the body, it must be ensured that upon exposure to body fluid it does not corrode in harmful ways. The effect that laser autogenous brazing has on the biocompatibility of dissimilar joined nickel titanium to stainless steel samples is thus explored. While initially both of these materials are considered to be biocompatible on their own, the laser treatment may change much of the behavior. Thermally induced changes in the oxide layers, grain refinement, and galvanic effects all influence the biocompatibility. Nickel release rate, polarization, hemolysis, and cytotoxicity tests are used to help quantify the changes and ascertain the biocompatibility of the joints. To directly exert a beneficial influence on materials’ corrosion properties laser shock peening (LSP) is performed, with a particular focus on the stress corrosion cracking (SCC) behavior. Resulting from the combination of an applied load on a susceptible material exposed to a corrosive environment, SCC can cause sudden material failure. Stainless steel, high strength steel, and brass are subjected to LSP and their differing corrosion responses are determined via cathodic charging, hardness, mechanical U-bend, Kelvin Probe Force Microscopy, and SEM imaging. A description accounting for the differing behavior of each material is provided as well as considerations for improving the effectiveness of the process. SCC can occur by several different physical processes, and to fully encapsulate the ways in which LSP provides mitigation, the interaction of microstructure changes induced by LSP on SCC mechanisms is determined. Hydrogen absorbed from the corrosive environment can cause phase changes to the material. Cathodic charging and subsequent X-ray diffraction is used to analyze the phase change of sample with and without LSP processing. Lattice dislocations play an important role, and transmission electron microscopy helps to aid in the analysis. A finite element model providing spatially resolved dislocation densities from LSP processing is performed.

<p>Mathematical modeling of heat transfer is a common method utilized in designing thermal processes for food, modeling degradation kinetics of microorganisms and nutrients, designing food processing equipment as well as for process optimization and for ensuring scale-up feasibility of a product. It is essential to have all the necessary components for modeling including the geometry, boundary conditions, initial temperature, and the temperature-dependent thermal properties. Getting temperature-dependent thermal properties of food product is difficult due to the lack of effective and efficient devices or techniques. To show the influence of temperature-dependent thermal properties, retort processing of potato soup was simulated using both temperature-dependent (dynamic) and fixed thermal properties. Three methods, TPCell, Choi-Okos predictive model and KD2 Pro, were used to determine the thermal conductivity at 25°C and 120°C for comparison. The proximate composition of the sample was determined for prediction of thermal properties with the Choi-Okos model. The accuracy of simulation was evaluated based on the temperature at the cold spot and corresponding sterilization value. Results suggested that using temperature-dependent thermal properties in heat transfer modeling increased the accuracy of the simulation. Simulation performed with temperature-dependent properties obtained from TPCell matched very closely with experimental heat penetration data. Additionally, the sensitivity of temperature-dependent thermal properties obtained from TPCell in detecting variation in product formulation was evaluated. Four variations of potato soup were prepared to compare their respective lethality value. Thermal conductivity, specific heat capacity and density of the potato soups were measured, and simulation was performed using the measured thermal properties and a scheduled process as boundary conditions. Thermal properties of food product changed with the formulation which affected the processing time to achieve minimum lethality value. A significant difference in thermal conductivities was seen for these potato soups causing the scheduled process to be only suitable for thermal processing of some formulations while others would be undercooked that could lead to food safety risk. Since the thermal conductivity measurements were sensitive in detecting the difference in the formulation, it can be used as a tool to select a formulation that can best suit the processing conditions of the heat penetration tests. The technique described can be used for any thermal processes in the food industry including pasteurization, retort, and aseptic processing. This application will be beneficial for the industry to pre-screen the iterations and only select formulation that suits the scheduled process for successful heat penetration trials and reduce trial costs.</p>

Cheng Bo-ki. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 150-153). / Abstracts in English and Chinese. / Chapter chapter 1 --- Introduction --- p.10 / Chapter chapter 2 --- Background & Literature --- p.15 / Chapter 2.1 --- Why Environmental Design? --- p.15 / Comfort and Energy --- p.15 / "Our Problems: Energy, Environment, and Health" --- p.19 / Chapter 2.2 --- Knowledge in Environmental Design --- p.27 / What is Environmental Design? --- p.27 / Current knowledge in Environmental Design: Thermal Performance --- p.30 / Thermal Studies in Hong Kong --- p.37 / Chapter 2.3 --- Summary and Propositions --- p.42 / Chapter chapter 3 --- Scale Model Study --- p.47 / Chapter 3.1 --- Test Modules Application --- p.47 / Chapter 3.2 --- Research Methodology & Experimental Setup --- p.54 / Testing Facility in CUHK --- p.54 / Solarimeter Substitute --- p.58 / Chapter 3.3 --- Experimental Series --- p.61 / Chapter 3.3.1 --- Envelope Colour --- p.61 / Chapter 3.3.2 --- Windows --- p.73 / Chapter 3.3.3 --- Shading --- p.75 / Chapter 3.3.4 --- Thermal Mass --- p.80 / Chapter 3.3.5 --- Orientations --- p.83 / Chapter 3.3.6 --- "Combined Effects ofThermal Mass, Windows and Orientations" --- p.85 / Chapter 3.3.7 --- "Combined Effects ofThermal Mass, Shading and Orientations" --- p.88 / Chapter 3.4 --- Summary of Experiments --- p.90 / Chapter 3.5 --- Predicting Indoor Air Temperature --- p.93 / Chapter 3.5.1 --- Development of Predictive Formulas --- p.93 / Chapter 3.5.2 --- Parametric Study of Envelope Colour --- p.97 / Chapter 3.5.3 --- Parametric Study of Window Shading --- p.100 / Chapter chapter 4 --- Field Study --- p.104 / Chapter 4.1 --- Description of Housing Unit: Concord-I Block --- p.104 / Chapter 4.2 --- Experimental Setup --- p.105 / Chapter 4.3 --- Result of Field Measurement --- p.108 / Chapter 4.3.1 --- Perform ance of top-most floor --- p.108 / Chapter 4.3.2 --- Performance of Individual Rooms --- p.109 / Chapter 4.3.3 --- Effect of Orientation --- p.110 / Chapter 4.3.4 --- Indoor Thermal Comfort --- p.113 / Chapter 4.4 --- Summary of Field Measurement --- p.116 / Chapter chapter 5 --- Thermal Performance Prediction --- p.118 / Chapter chapter 6 --- Conclusion --- p.126 / Appendix 1 --- p.131 / Appendix 2 --- p.133 / Appendix 3 --- p.140