Showing papers on "Thermal energy published in 1998"

Energy input and mass redistribution by supernovae in the interstellar medium

Abstract: We present the results of numerical studies of supernova remnant evolution and its effects on galactic and globular cluster evolution. We show that parameters such as the density and the metallicity of the environment significantly influence the evolution of the remnant and thus change its effects on the global environment (e.g., globular clusters, galaxies) as a source of thermal and kinetic energy. We conducted our studies using a one-dimensional hydrodynamics code, in which we implemented a metallicity-dependent cooling function. Global time-dependent quantities such as the total kinetic and thermal energies and the radial extent are calculated for a grid of parameter sets. The quantities calculated are the total energy, the kinetic energy, the thermal energy, the radial extent, and the mass. We distinguished between the hot, rarefied bubble and the cold, dense shell, since these two phases are distinct in their roles in a gas-stellar system. We also present power-law fits to those quantities as a function of environmental parameters after the extensive cooling has ceased. The power-law fits enable simple incorporation of improved supernova energy input and matter redistribution (including the effect of the local conditions) in galactic/globular cluster models. Our results for the energetics of supernova remnants in the late stages of their expansion give total energies ranging from ≈ 9 × 1049 to ≈ 3 × 1050 ergs, with a typical case being ≈ 1050 ergs, depending on the surrounding environment. About 8.5 × 1049 ergs of this energy can be found in the form of kinetic energy. Supernovae play an important role in the evolution of the interstellar medium and galaxies as a whole, providing mechanisms for kinetic energy input and for phase transitions of the interstellar medium. However, we have found that the total energy input per supernova is about 1 order of magnitude smaller than the initial explosion energy.

Method and apparatus for high precision variable rate material removal and modification

Abstract: A method and apparatus is disclosed for fast precise material processing and modification which minimizes collateral damage. Utilizing optimized, pulsed electromagnetic energy parameters leads to an interaction regime which minimizes residual energy deposition. Advantageously, removal of cumulative pulse train residual energy is further maximized through the rapid progression of the ablation front which move faster than the thermal energy diffusion front, thus ensuring substantial removal of residual energy to further minimize collateral thermal damage.

Subsurface heating of material

Abstract: A method and system of delivering energy to material in which energy is converted to thermal energy in the material, and prior to significant therapeutic or other physiological change in a selected or target region of the material, results in a temperature rise which is maximum in a selected region of the material but which is insufficient to cause significant therapeutic or other physiological effect, the system for selective preheating of subsurface target regions of material such as human tissue including an energy source to preheat the material or tissue, a passive or active cooling means, and a device for delivering therapeutic or treatment energy, such as pulsed, electromagnetic, laser or non-coherent energy, to tissue during or after the preheating and cooling of the tissue.

Dehumidifying air conditioner

Abstract: A dehumidifying air-conditioning apparatus has a compact arrangement including an integral combination of a heat pump as a heat source drivable by a thermal energy from an external source and a desiccant air-conditioning unit, and can achieve a high energy efficiency. The dehumidifying air-conditioning apparatus through which processing air and regenerating air flows alternately through a first desiccant 103 has an adsorption heat pump having first and second heat exchanger assemblies 10 A, 10 B of closed structure each having desiccant heat exchangers 1 A, 1 B with a second desiccant for adsorbing or desorbing a refrigerant and refrigerant heat exchangers 3 A, 3 B for evaporating or condensing the refrigerant. The refrigerant heat exchangers of the first and second heat exchanger assemblies communicate with each other via a path through a restriction 7 . The processing air and the regenerating air flow alternately through the refrigerant heat exchangers of the first and second heat exchanger assemblies of the adsorption heat pumps, and a heating medium for driving the adsorption heat pumps is guided to and heated by the desiccant heat exchangers directly in communication with the refrigerant heat exchangers through which the regenerating air flows.

A panel-shaped, hybrid photovoltaic/thermal device

Abstract: A panel-shaped hybrid photovoltaic/thermal device (1) comprising metal absorption means (6) for converting solar energy into thermal energy, and laminated, panel-shaped photovoltaic means (2) comprising photovoltaic cells (3) of a crystalline silicon for converting solar energy into electric energy. The photovoltaic means (2) and the absorption means (6) have been joined to form a single assembly with the interposition of a metal-containing plastic material (10) having bonding properties. The device (1) is constructionally simple and suited for optimizing the electric and thermal efficiency.

Method and apparatus for thermal energy storage

Abstract: Methods and apparatus for extracting stored thermal energy using a combined internal and external melt cycle are disclosed. The present invention relates, in one aspect, to a heat exchange system which uses both an internal melt cycle and an external melt cycle to extract stored thermal energy. The heat exchange system includes a thermal energy storage medium and a heat exchanger which is in communication with the thermal energy storage medium. The heat exchanger is arranged to hold a heat exchange liquid and to facilitate the indirect transfer of heat between the heat exchange liquid and the thermal energy storage medium. The heat exchange system further includes a fluid supply which provides a fluid which directly contacts the thermal energy storage medium to transfer heat between the fluid and the thermal energy storage medium.

Hybrid Method for Determining the Fraction of Plastic Work Converted to Heat

Abstract: The fraction of plastic work converted to heat is typically measured either by nearly isothermal experiments, in which the thermal energy is measured during a deformation experiment with a calorimeter, or by adiabatic experiments, in which the thermal energy is determined from the temperature rise, measured either during the test or immediately after the test by dropping the sample into a calorimeter. In the present work, the temperature is measured with a single fine-wire thermocouple. The restriction to adiabatic loadings is relaxed by using a hybrid method that combines the measurements with finite difference simulations to calculate the heat losses that occur during the test. These heat losses are then accounted for in the final energy balance to determine the fraction of plastic work converted to heat. The method is applied to annealed 302 stainless steel. The results show that the fraction of plastic work converted to heat is a decreasing function ranging from 0.7 to 0.4 over a tensile strain range of 0 to 0.15. An analysis of the restrictions to this method and of the potential errors is given.

In-situ short circuit protection system and method for high-energy electrochemical cells

Abstract: An in situ thermal management system for an energy storage device. The energy storage device includes a plurality of energy storage cells each being coupled in parallel to common positive and negative connections. Each of the energy storage cells, in accordance with the cell's technology, dimensions, and thermal/electrical properties, is configured to have a ratio of energy content-to-contact surface area such that thermal energy produced by a short-circuit in a particular cell is conducted to a cell adjacent the particular cell so as to prevent the temperature of the particular cell from exceeding a breakdown temperature. In one embodiment, a fuse is coupled in series with each of a number of energy storage cells. The fuses are activated by a current spike capacitively produced by a cell upon occurrence of a short-circuit in the cell, thereby electrically isolating the short-circuited cell from the common positive and negative connections.

Statistical theory of cluster cooling in rare gas. I. Energy transfer analysis for palladium clusters in helium

Abstract: The cooling and heating of palladium clusters Pd13 and Pd55 by binary collisions with atoms of a surrounding helium gas are studied by means of molecular dynamics simulation. The efficiency of the collisional energy transfer is determined as a function of cluster and gas temperature and of cluster phase, the cluster being in either a solid or a liquid phase. A simple statistical analysis is presented for the energy transfer between a cluster and a rare gas atom. The analysis is based on an ergodic collision assumption of microcanonical relaxation in each collision. The deviation from this limiting law is collected in a collision efficiency factor which reflects incomplete energy redistribution during the lifetime of the collision complex. The thermal energy and change in heat capacity observed for the clusters at the freezing (melting) transition is accounted for by a parametrized density of states reflecting separate contributions from a solid and a molten structure. The same density of states is then used in the ergodic collision theory for the analysis of energy transfer.

A novel method to determine collisional energy transfer efficiency by Fourier transform ion cyclotron resonance mass spectrometry

Abstract: A novel method is presented here to determine accurately the conversion efficiency in low energy collision processes. Using blackbody infrared radiation, the initial thermal energy of a selected molecular ion is both well defined and well known. Collisional activation is subsequently used to probe the additional energy needed to reach a particular final internal energy distribution, characterized by a given fragmentation rate (e.g. 50% of the molecular ion being decomposed). The method is discussed for collision induced dissociation under multiple collision conditions using resonant excitation in a Fourier transform ion cyclotron resonance ion trap. By variation of the thermal energy content the collisional energy necessary to obtain 50% fragmentation rate is also changed. Knowing this change, the collisional to internal energy transfer can accurately be determined. In the case of Leucine-Enkephaline using Ar collision gas it was shown that 4.4% of the laboratory frame collision energy is converted into internal energy in the resonant excitation collision cascade. In individual collisions 9.6% of the centre of mass collision energy is converted into internal energy. Note, that this value is accurately determined as an average for collisions in the 4‐6 eV centre of mass collision energy range, but is approximately the same in the 0‐4 eV range as well. # 1998 John Wiley & Sons, Ltd. One of the big challenges in bio-macromolecular research is to determine the relationship between molecular structure and functionality of large polyatomic molecules. Mass spectrometric studies are more and more frequently employed in the investigation of these macromolecules. Determination of molecular structure using tandem mass spectrometry relies heavily on gas-phase dissociative processes. Dissociation products of large polyatomic molecules provide information on the structure and composition of the molecule, for instance the primary and secondary structure of a peptide. The internal energy, the total energy of a particular species above its electronic, vibrational and rotational ground state, needs to be higher than the dissociation threshold to induce structurally relevant fragmentation. 1 The effect of collisional excitation strongly depends on the time scale of an experiment and the size of the molecule. In many cases reactions take place in a time window anywhere from picosecond to microsecond time scales. Typically these experiments employ an energetic mass selected beam which is transported through a collision cell filled with an inert collision gas, or through a photodissociation cell where the beam is allowed to interact briefly with a focused laser beam. In the interaction region the internal energy is increased such that fast (ps‐ms) dissociation is induced. The product ions in the beam are mass analysed after leaving the dissociation cell. These experiments become inadequate when applied to macromolecular systems, as the number of degrees of freedom increases dramatically. The internal energy required for fragmentation within a given time period increases with the number of degrees of freedom in the molecule. For large molecules, the fragmentation rates will be so low that no measurable fragmentation will occur on the time scale of these beam-type experiments. Consequently, there is a great need for new tools to explore the structure‐function relationship of macromolecules. The question arises as to what the role of gas-phase collisions can be in the examination of macromolecules. Different molecular conformations may

Mems-based scanning calorimeter for thermodynamic properties of nanostructures

Abstract: Thermodynamic properties of small structures, such as the melting points and the process of mass transport, can be considerably different compared to material in the bulk form. Calorimetry is the standard experimental technique used to measure thermodynamics properties. However, this technique is extremely difficult to use for the study of small structures because the amount of energy exchanged during the measurement is extremely small - proportional to the amount of material. In order to measure small amounts of thermal energy we have scaled down the physical size of the calorimeter using MEMS technology. This thin-film differential scanning calorimeter has extremely high sensitivity, 0.01 mJ cm2, and is capable of measuring the melting phenomenon of 1 A of Sn deposited onto a SiN surface. In this article we investigate the size dependence of both the melting point and the heat of fusion for ultrathin films of Sn nanonstructures using multiple evaporation and thermal annealing cycles.

Integrated gasification combined cycle power plant with kalina bottoming cycle

Abstract: An integrated gasification combined cycle plant is combined with a Kalina bottoming cycle. High thermal energy streams 31, 69, 169 from the gasification system are provided in heat exchange relation with the two component working fluid mixture at appropriate locations along the Kalina bottoming cycle units to supplement the thermal energy from the gas turbine exhaust 28 which heats the working fluid supplied to the vapor turbines. Particularly, low temperature heat recovery fluid from the low temperature cooling section 50 b of the gasification system lies in heat exchange relation 27 with the condensed working fluid from the distillation/condensation sub-system of the Kalina cycle to preheat the working fluid prior to entry into the heat recovery vapor generator 12. Heat recovery fluid from the high temperature gas cooling section 50 a of the gasification system is placed in heat exchange relation 23 and 65 with the working fluid at an intermediate location along the heat recovery vapor generator 12. By supplementing the heat of the gas turbine exhaust with available heat from the gasification system, and optimal integration, increased power output and improved efficiency are obtained.

Quadruple heat exchanger

Abstract: A heat exchanger having a plurality of coaxially aligned chambers for providing radiant, thermal heat transfer between a plurality of separately contained fluids within a single unit and a helical tube having at least one portion positioned within at least one of the chambers. A first, second, third, and fourth chambers are in coaxial alignment. The heat exchanger heats a cryogenic liquid to a gas phase using four different heat transfer fluids in one contained unit without mixing any of the fluids in the exchanger, thus reducing the size and cost, while increasing the efficiency of the heat exchanger.

Minimum Heating Entry Trajectories for Reusable Launch Vehicles

Abstract: A e nite control volume heat transfer analysis is coupled to a e ight-path optimization and integration algorithm forthepurposeofcalculatingconductiveheatratesand transienttemperatureeffectswithin thethermalprotection system of a reusable launch vehicle. Results are obtained for three different thermal protection system concepts: tile, blanket, and metallic. The optimization algorithm is based on the energy state approximation and is used to generate optimal entry trajectories minimizing the following three criteria: 1 ) the thermal energy absorbed at the vehicle surface, 2 ) the heat load applied to the vehicle, and 3 ) the thermal energy absorbed by the internal structure. Results indicate that allthreetrajectoriesproduce comparablepeak internal structure temperatures for a given thermal protection system, with the trajectory minimizing the heat load applied to the vehicle producing thelowestpeaktemperature.However,ifthemaximum stagnation temperatureconstraintatthenoseof thevehicle is increased from 3000 to 4000 ±F, the trajectory minimizing the thermal energy absorbed by the internal structure becomes superior. Further, the trajectory with the 4000 ±F limit gives a peak internal structure temperature 25 ±F less than the one with the 3000 ± F limit.

Thermal energy storage and transfer assembly

Abstract: A thermal energy storage and transfer assembly is disclosed for use in electron beam generating devices that generate residual energy. The residual energy comprises radiant thermal energy and kinetic energy of back scattered electrons. The thermal energy storage and transfer assembly absorbs and stores an amount of the residual energy to reduce the heat load on other components in the electron beam generating device. The thermal energy storage and transfer device comprises a body portion of a sufficient thermal capacity to permit the rate of transfer of the amount of the residual energy absorbed into the assembly to substantially exceed the rate of transfer of the amount of the residual energy out of the assembly. The assembly also comprises a heat exchange chamber filled with a circulating fluid that transfers the thermal energy out of the assembly. Additionally, in an x-ray generating device, an x-ray transmissive filter suitable for absorbing residual energy is positioned between the anode and an x-ray transmissive window. The filter reduces the exposure of the window to the residual energy. The filter may additionally comprise a coating layer that further reduces the exposure of the window to the residual energy.

High-performance energy transfer system and method for thermal processing applications

Abstract: An apparatus and method supports thermal processing of a microelectronic device such as a semiconductor chip in a substrate by heating the substrate with secondary radiation from an energy transfer device 40, which has a first set of energy transfer regions comprised of an emissive and thermally conductive material, and a second set of thermally insulating regions comprised of a reduced emissivity and reduced thermal conductivity material or free space. A multi-zone radiant energy source 30 provides radiative energy to energy transfer device 40, with a process controller 36, preferably a multi-zone controller, altering the amount of energy provided by each heat zone associated with each emissive region of energy transfer device 40. Sensors detect the thermal energy level of each energy transfer region to allow controller 36 to adjust the secondary radiation emitted by each region in real time, resulting in a predetermined and controlled distribution of thermal energy on substrate 20. Energy transfer device 40 can have plural emissive and thermally conductive concentric rings separated from each other by reduced emissivity and reduced thermal conductivity regions such as free space gaps 42. Alternatively, a solid plate 54 having an emissive coating or emissive surface 52 can have reduced emissivity and reduced conductivity isolation regions such as trenches 56 for defining the multi-zone high-emissivity and high thermal conductivity energy transfer regions.

Thermoelectric refrigerator/warmer using no external power, and refrigerating/warming method

Abstract: A thermoelectric refrigerator/warmer using no external power, and a refrigerating/warming method are disclosed. A natural energy such as the solar energy is utilized so as to make an external power needless. Thus a thermoelectric device is made to convert the natural energy into electric power based on the difference between the internal and external temperatures, and this electric energy is converted again into a thermal energy by means of a peltier device, thereby varying the internal temperature of the apparatus. An outer part 4 of a thermoelectric device 3 is attached on the side face of the refrigerator/warmer, and an inner part 5 of it is attached on a bottom plate 7 of the refrigerator/warmer. Thus a thermoelectromotive force is generated based on the temperature difference between outside and inside of the refrigerator/warmer. The voltage thus generated is supplied to a peltier device 6 to cool or heat the bottom plate 7. In this manner, the thermoelectric refrigerator/warmer can be operated even without using an external power.

Evaporative concentration apparatus for waste water

Abstract: The present invention provides an evaporative concentration apparatus for waste water having an evaporating vessel 2 for evaporatively concentrating waste water and a heater 3 for circularly heating an in-vessel liquid in the evaporating vessel 2, in which the whole or part of thermal energy of generated steam 6 discharged from the evaporating vessel 2 is recovered by an absorption heat pump 29, and the thermal energy is supplied to the heater 3. According to the present invention, evaporative concentration can be effected efficiently in the evaporating vessel by effectively utilizing the thermal energy of generated steam, and also the operation of evaporative concentration apparatus can be performed stably by stably securing heating steam quantity.

Effects of Heat of Reaction on Homogeneous Compressible Turbulence

Abstract: Direct numerical simulations (DNS) of homogeneous compressible turbulent reacting flows are conducted to investigate the effects of heat of reaction on the solenoidal and the dilatational turbulent motions. Consistent with the previous theoretical results, it is shown that the heat of reaction does not have a significant effect on the low order moments of the solenoidal velocity. However, the variances of dilatation, pressure, temperature, and density, increase significantly due to heat release. Also, the magnitudes of the skewness and the kurtosis of dilatation increase significantly as a result of heat of reaction. The high negative values of the dilatation correspond to localized structures with low probability of existence. The heat of reaction also enhances the amplitude and the frequency of the oscillations of the pressure-dilatation correlation. Examination of the energy transfer among rotational and compressive components of the kinetic energy and the internal energy indicates that the energy of the reaction is transferred to the compressive component of the kinetic energy by the pressure-dilatation correlation. The advection term then transfer the energy from the compressive component of the kinetic energy to its rotational component. While the interactions between compressive component of the kinetic energy and the internal energy are significant, those between the rotational and the compressive components of the kinetic energy are relatively weak.

The energy balance in the plasma of a coaxial plasma opening switch

Abstract: The two-dimensional energy flow in the plasma of a coaxial plasma opening switch (POS), during the Hall-induced shock penetration of a magnetic field, is analyzed. The electron collisionality is assumed to be high enough that the dissipated magnetic-field energy becomes electron thermal energy. It is shown that that part of the magnetic-field energy (a third) that is dissipated at the cathode at the generator side of the plasma, becomes an electron kinetic energy, that is convected along the current channel. It is also shown that in the magnetized plasma magnetic-field energy flows backwards towards the generator. The third new result is that inside the shock front, electron thermal energy is converted into magnetic-field energy, contrary to the usual situation in shock waves in which field energy is converted into particle thermal energy.

Advanced thermo-electronic systems for hybrid electric vehicles

Abstract: A hybrid propulsion system for vehicles having an electronic storage and drive system for driving a vehicle and a thermal engine for charging and energizing the electrical storage and drive system, the thermal engine having a thermal energy source with a compressor and turbine combination operating in a Brayton cycle with the compressor being driven by an electrical motor and the turbine driving a generator, the compressor compressing the motive gas which is thermally heated by the thermal energy source and the heated gas expanding in the turbine.

Controlled energy density microwave-assisted processes

Abstract: An effect is induced within a chemical system consisting of at least two substances having differing degrees of microwave transparency, by exposing the mixture to focused microwave energy having a generally uniform energy density level, and an energy density at a level exceeding the capacity of at least one of the substances to dissipate the energy as thermal energy. The treatment is carried out until the thermodynamic state of the system is in a non-equilibrium state. The rate at which the effect is carried out is substantially increased over that which would be expected under equilibrium thermodynamic conditions. The effect may consist of an exothermic or endothermic chemical reaction or a separation process including a volatilization process.

Relativistic thermodynamics

Abstract: A generally relativistic theory of thermodynamics is developed, based on four main physical principles: heat is a local form of energy, therefore described by a thermal energy tensor; conservation of mass, equivalent to conservation of heat, or the local first law; entropy is a local current; and non-destruction of entropy, or the local second law A fluid is defined by the thermostatic energy tensor being isotropic The entropy current is related to the other fields by certain equations, including a generalised Gibbs equation for the thermostatic entropy, followed by linear and quadratic terms in the dissipative (thermal minus thermostatic) energy tensor Then the second law suggests certain equations for the dissipative energy tensor, generalising the Israel- Stewart dissipative relations, which describe heat conduction and viscosity including relativistic effects and relaxation effects In the thermostatic case, the perfect-fluid model is recovered In the linear approximation for entropy, the Eckart theory is recovered In the quadratic approximation for entropy, the theory is similar to that of Israel & Stewart, but involving neither state-space differentials, nor a non-equilibrium Gibbs equation, nor non-material frames Also, unlike conventional thermodynamics, the thermal energy density is not assumed to be purely thermostatic, though this is derived in the linear approximation Otherwise, the theory reduces in the non- relativistic limit to the extended thermodynamics of irreversible processes due to Mueller The dissipative energy density seems to be a new thermodynamical field, but also exists in relativistic kinetic theory of gases