The purpose of this study is to establish an Inside Temperature (IT) method for estimating temperatures in steady wave fronts in a thermoviscous material. A fundamental assumption that the material in the wave front, was approximately in an equilibrium state was used in this method. A further assumption that heat transport was neglected was used in the IT dQ=0 method, while in the IT IM method, the work done by the thermal stress was offset by heat transport. Two irreversible thermodynamic equations for the temperature in the wave front derived were connected with the Hugoniot function and the Mie-Grüneisen equation, respectively. To verify the efficacy of the IT method, three temperature distributions were estimated qualitatively using an equation for entropy including no assumption on heat transport, that including the assumption used in the IT dQ=0 method, and that in the IT IM method. These three distributions suggested that the temperatures were overestimated by the IT dQ=0 method, while the IT IM method was effective for shock compressions where the effect of viscosity was distinguished.

Natural convection heat and mass transfer in a soil saturated with light fuel vapor and heated from one side is modeled and solved numerically. The system is simulated as a porous medium in a large horizontal enclosure exposed to ambient air from the top and saturated with a fuel vapor from the bottom. It is assumed that one of the vertical boundaries is heated to a constant temperature while the other vertical boundary kept cold at the ambient temperature. The problem is approximated as a two-dimensional, steady state, laminar flow with constant properties. The rate of outflow of species is calculated together with the rates of heat and mass transfer. Also, flow, temperature and species distributions are shown. For a thermally driven flow, i.e., N<1.0, the flow is driven into the cavity from a distance if the strength of the heat source and/or the permeability of the porous medium is high. For N>1.0, solutal plumes and complex flow pattern are formed as N increases. Such results will aid in providing guidelines for reducing the fire hazards from fuel wetted soils.

Deepwater activities are the future of the Offshore Oil and Gas Industry. Huge reserves have been located in the Gulf of Mexico as well as off the Coast of West Africa and Brazil. The development of floating production platforms and vessels offers challenges to the facilities engineer who must consider new materials to meet stringent topsides weight limitations. A critical technology for facilities piping in offshore platforms is joining technique. This paper discusses the development of a hybrid joining approach by using heat-activated coupling and adhesive bonding. The technique procedure is presented via specimen fabrication. A total of eleven coupled specimens are prepared and evaluated using standardized internal pressure tests. The feasibility of this new joining technique in offshore piping is discussed based on the internal pressure test results.

The solid-state welding method was applied under atmospheric conditions by using metal powder medium which was interposed in the space between the two solid bars of specimen (i.e., base metal), and was compressed longitudinally and simultaneously current was conducted to generate Joule thermal heat. Some fundamental data on the mechanical and metallurgical properties of the joint were obtained by using resistance welding. In the experiments, the specimen materials used as base metals in this study were pure aluminum, stainless steel and titanium bars of solid, and the powder media were aluminum, nickel and silicon powder. The mixed silicon powder medium increases electric resistance between base metals, moreover, to obtain mechanical properties. Four experiments were conducted with different specimen; The first experiment used two solid aluminum specimen bars with aluminum powder medium. The second, two solid aluminum specimen bars with mixed aluminum and nickel powder media. The third, two solid aluminum specimen bars with mixed nickel and silicon powder media. And the fourth, solid specimen were different materials and had relatively different melting points. Such as solid aluminum and stainless steel (SUS430) with mixed nickel and silicon powder media, and solid aluminum and titanium with mixed aluminum and nickel powder media. Data were obtained with the intent of optimizing the method using powder medium between a pair of solid sample specimen and observation, analysis and assessment were made with microscope. Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). X-ray Diffraction (XRD), tensile strength, Vickers hardness and bending U-shape flexure tests.

Porous radiant burners are widely used in industry to provide a uniform source of heat flux with reduced emissions. Such burners have provided high rates of heat transfer by radiation while preventing flame flashback. The work to be presented relates to the modeling of the combustion process in a double-layered flat porous burner. The burner employs a low porosity layer on the upstream side and high porosity layer on the downstream side of the homogenous fuel-air mixture flow. The nonequilibrium model is adopted. The energy equations for the gas and solid media are solved numerically with a one step reaction (Arrhenius type) energy release rate for the gas-phase. The solid phase is considered to be non-reactive. The thermophysical properties of the gas and solid phases are assumed to be functions of temperature. The effects of thermal conductivity and thickness of the layers on the flame stabilization within the porous medium and radiant energy output are investigated and discussed. The high thermal conductivity layer diffuses heat and thus has significant effects on the flame location and flame temperature. However, the high thermal conductivity of the layer also contributes to a decrease in the radiant energy. It was found that generally the flame stabilizes at the interface between the two layers. When the thermal conductivity of the upstream low porosity layer was too low (e.g. 0.1 W/m.K), the flame was stabilized within the low porosity layer.

Modeling of heat-activated coupled graphite fiber reinforced composite piping in a cryogenic environment was investigated in this study. A 2-dimensional heat diffusion model was used to capture the essentials of thermal transport through the thickness of a heat-activated coupled (HAC) graphite epoxy composite-to-composite pipe joint. The resulting boundary value problem was solved using an Alternating Direction Implicit (ADI) finite difference model (FDM). Simulated numerical transient temperature distributions are predicted for comparison with experimental results.

In the previous study, two Inside Temperature (IT dQ=0 and IT IM ) methods for estimating the temperature distributions in steady wave fronts in a thermoviscous material were established and the IT IM method was shown qualitatively to be effective for shock compressions where the effect of viscosity was distinguished. In this paper, these two methods are applied to the shock compressions of Yittria-doped Tetragonal Zirconia (YTZ) that is a thermoviscous material with a multiple shock Hugoniot. The YTZ Hugoniot consists of three partial curves including two kinks, that are the Hugoniot Elastic Limit (HEL) and the phase transition point. The shock temperatures evaluated by the IT IM method were close to the accurate temperatures obtained by the Walsh-Christian method in the whole stress range to 140 GPa examined here. Furthermore, the inside temperature distributions were approximately accurate because the effect of viscosity was distinguished in the shock compression. By these facts, it was considered that the fundamental assumption and the assumption on heat transport used in the IT IM method were valid and as a result, this method was effective. In addition, the influence of heat transport on the temperatures and thermoelastic stresses was examined.

Since the middle of this century the growing fact of the unexpected environmental conditions and the rapid increase in the energy consumption have resulted in the fact that the efficient use of the energy and to exploit a new and renewable energy resources are inevitable. In the recent years, increasing importance in the issue of the best use of available energy resources are discussed with the application of the combined heat-power plants. In this paper, the performance of the conventional energy plants and combined heat-power plants are compared. For this reason a new design criterions for the combined heat-power plant are introduced here. The rationality of these new design criterions are tested in thermal energy and gas turbine plants. The obtained results are then compared with the conventional energy plants. It is proven that this new design methodology will provide more energy saving and minimize the heat losses that is produced during energy production.

The curing process of epoxy prepreg was studied by means of Differential Scanning Calorimeter. The dynamic, isothermal, and combinations of dynamic and isothermal measurements were done over selected temperature ranges and isothermal cure temperatures. The heats of reaction for dynamic and isothermal cure were determined. The results show that the heat of isothermal-cure reaction increased with the increment of temperature. The degree of cure was calculated from the heat of isothermal-cure reaction. The complete cure reaction could be achieved at 220 °C within the very short cure time. The changes of cure rate with time were given for the studied isothermal cure temperatures. To simulate the relationship between the cure rate and degree of cure, the autocatalytic model was used and the four parameters were calculated. Except in the late stage of cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into the model. The modified model greatly improved the predicated data at the late stage of cure reaction.

A discussion of the potential and test results of detection and removal hydrates from subsea pipelines and completion systems by the direct application of heat by the circulation of locally heated seawater.

A study in collaboration between investigators at Southern University and Louisiana State University in Baton Rouge, Louisiana and NASA/MSFC is examining materials for modeling and analysis of heat-activated thermal coupling for joining composite to composite/alloy structures. The short-term objectives of this research are to develop a method for joining composite or alloy structures, as well as to study the effects of thermal stress on composite-to-alloy joints. This investigation will result in the selection of a suitable metallic alloy. Al-Li alloys have potential for this purpose in aerospace applications due to their excellent strength-to-weight ratio. The study of Al-Li and other alloys is of significant importance to this and other aerospace as well as offshore related interests. Further research will incorporate the use of computer aided design and rapid prototype hardware for conceptual design and verification of a potential composite piping delivery system.

Modeling of a heat-activated coupling process of fiberglass reinforced epoxy composite pipe with a copper nickel 90/10 (Cu 90% Ni 10%) alloy pipe was investigated in this study. A nonlinear-coupled two-dimensional heat diffusion model was used to capture the essentials of in-situ thermal transport during the curing process through the thickness of the prepreg wrapping layers. The resulting nonlinear boundary value problem was solved using an Alternating Direction Implicit (ADI) finite difference model (FDM). Transient temperature distributions and degree of cure were predicted for the prepreg layers with and without a heating source at the side of the alloy pipe. A reasonable agreement was found between the predicted temperatures and the experimental results. Measures to improve the curing quality of prepreg layers were discussed based on the modeling results.

An electrical resistance welding method was applied under atmospheric conditions by using one of metal powder medium or media mixture which was sandwiched in the space between the two solid metal bars of specimen (i.e., solid specimen material), and was compressed longitudinally by oil pressure servo control electrodes (upper and bottom) and simultaneously current was conducted to generate Joule thermal heat. In the joining experiments, a solid aluminum specimen material was used as a basis material, and was joined to another solid aluminum specimen material or one of four other solid specimen materials with different melting points by using resistance-welding apparatus. Some fundamental data on the mechanical properties of the joint were obtained by material testing. In the experiments, the specimen used as solid specimen materials in this study were pure aluminum, copper, stainless steel, carbon steel and titanium bars of solid specimen, and the powder media were aluminum, nickel and silicon powder. Proper mixed ratios of total amount of the powder media were determined for reliable joining, and material testing was prepared for mechanical properties. The obtained data were examined with the intent of optimizing the method using metal powder media between a pair of specimen materials and were compared with that of the solid specimen material, in terms of tensile strength, Vickers hardness, bending U-shape flexure stiffness. On the tensile strength and Vickers hardness, they were found to be reliable, but on bending U-shape flexure stiffness, they were not definite enough.

Composition and temperature induced natural convection within an open topped vertical circular enclosure has been numerically investigated. A theoretical model that describes the mass, heat and momentum transport processes in a 2-dimensional axisymmetric domain is presented. The model included consideration of the transient development of natural convection flow, density and thermophysical property variations. The results presented are for a n-Pentane liquid vapor diffusing into Air. A description of the transient temperature and concentration gradients development is given along with their effects on the flow field progression.

Combustion processes with excess enthalpy are described with examples given. It is shown that different processes, such as heat and mass transfer, phase and chemical changes are involved. Moreover, flames with excess enthalpy can be encountered in a variety of forms such as laminar or turbulent, within homogeneous or heterogeneous systems involving stationary or unsteady processes, with pulse or spin combustion and as cellular flames. It is to be shown that mainly due to the increase in the chemical reaction rates within the combustion zone, the excess enthalpy state can lead to substantial increases in the burning rates, widening the associated flammability limits and modifying the preignition processes. Some applications that can benefit from the use of such flames are outlined.

Preliminary study of a composite pipe Tee-joint using heat coupling technology was conducted in this paper. The cutting process of the pipes for the Tee-joint was developed. Because the cutting edges of the pipes were coarse, it is necessary to smooth them. Both epoxy resin and prepreg were applied to the joined areas of the pipes. Shrink tape was also applied to the outside of the prepreg to add pressure and compression force. An optimized cure cycle for the epoxy prepreg used as the bonding materials was determined from the thermal cure analysis. The cure process of the joined pipes by epoxy prepreg was conducted in a specially designed oven. The total cure time was about 138 minutes. Several factors, including the thickness and length of the prepreg applied and the adhesive applied to the joints, have been considered in designing Teejoints. The hydrostatic pressure test results showed that the thickness of the wrapped epoxy prepreg had a very important effect on the quality of the joined pipes in terms of pressure.

Polymer covered cylindrical rolls are typically used in different paper machine sections like in calenders and in coating units. The main reason for the use of soft-coated rolls is that by using the soft rolls the contact area becomes larger. Strongly loaded line contact causes deformations and heat generation in the polymer cover. In paper production process impurities, like paper pieces, may catch on the surface of the roll. Impurities cause locally larger deformation in the cover. The local deformation produces a higher local temperature area, which can cause cracks in the cover, to loosen the cover from the base and to fracture the cover locally. If a local failure happens the fragments of the cover can damage also the other rolls. In this paper an operation monitoring system for on-line monitoring of roll cover is presented. The system is installed in a laboratory pilot roll installation, where the rolling contact consists of a hard and a soft roll. The measurement system consists of on-line measurement of acoustic emission (AE) of the roll. Additionally the temperature distribution of the roll, the ploymer cover and the position angle of the roll are measured. The measurement signal is transferred from the rotating roll via wireless local area network (WLAN) to the measurement computer. The measurement control computer is connected to the LAN of the laboratory and the measurements can be followed and analyzed with different computers and also via Internet. The paper describes the principles of acoustic emission signal processing and analysis and the construction of the wireless Ethernet-based operation monitoring system.

A heat leveler machine can create valuable economical losses in fault situations. By applying on-line monitoring of the vibration signatures, the machine can be followed continuously and the changes in the process and in condition of the mahcine can be detected immediately. The on-line monitoring consists of the on-line adjustment of drive parameters as well as quality control. Generally several kinds of different sensor types are applied into the system. On-line monitoring of rolling bearings usually includes vibration measurement sensors. A heat leveler operates at differnt speeds and loads and the direction of process can be reversed during run. The reliability of the results of the on-line monitoring can be increased by measuring simultaneously different parameters that influence on the vibration of the machine. This method is called multi-parameter monitoring. This paper focuses on the possibilities of on-line monitoring of the support bearings in a metal slab heat leveler by vibration measurements. The leveler is equipped with vibration sensors of low frequencies as well as high frequency acoustic emission sensors. The main issue is experimenting different kind of signal processing methods and optimal procedures are then programmed to the on-line monitoring computer. The measurements in this study were performed in industrial circumstances, in a steel mill. The test machine was a heat leveler machine in normal industrial usage. A method of varying limit values is presented. For this, acoustic emission and acceleration rms-signals are applied. Values are determined by the forces in the leveling cylinders. Forces correspond to the deformation resistance of the steel plates.

A fuzzy control (FLC) approach has been developed to control the curing process of a polymeric laminate used as the bonding material for the heat-activated coupling (HAC) of a fiberglass composite to Cu-Ni alloy pipe. Controlling the temperature of the curing environment is required in order to achieve uniform cure within the bonding prepreg. Without temperature control, the alloy side of the coupling is essentially a heat sink. Therefore, a controlled heat source on the alloy pipe is needed to compensate for the heat sink effect that tends to decrease curing temperatures within the laminate. The simulation results obtained show that the curing process of HAC of a composite-to-alloy pipe is significantly improved with required uniform cure characteristics being obtained through the thickness of the laminate.

In the paper development of used ceramic materials and ways of their production with the aid of heat spraying is presented. According to a needness of continuous increase of coating’s mechanical resistance (high wearability, low brittlesness), corrosion resistance and profitable thermal and electric properties, current ceramic materials characterized by more and more attractive useful properties are described. Also a role of flame and plasma spraying including developmental trends towards prodution of coatings are underlined. The paper contains the own solution of plasma spraying of coatings consists in operation of the process under atmospheric pressure with gaseous ring-shaped protective jet. Additionally, proper choice of spraying’s parameters and some interesting characteristics of coatings are presented along with the examination of their structure (i. e. a rate of fusion, an oxidation of granules in a coating). Moreover the applications of coatings on machine parts (i. e. mechanical seal of impeller pumps, blades of turbines) are mentioned.