Showing papers on "Thermal energy published in 1987"

Thermal energy storage apparatus using encapsulated phase change material

Abstract: The invention relates to a thermal energy storage apparatus wherein a housing defines a chamber and wherein inlet and outlet means communicate with the chamber. A channelling means is positioned within the chamber for dividing the flow stream of a heat exchange fluid into a plurality of separate flow streams and for directing the heat exchange fluid to flow therethrough. Positioned within the channelling means is means for storing and releasing the thermal energy by heat transfer to and from the exchange fluid as the fluid passes in contacting relation with the thermal energy storing and releasing means as the fluid passes through the housing.

Physics of Water and Ice: Implications for Cryofixation

Abstract: Cryotechniques in biological electron microscopy have one aspect in common: the use of low temperatures to stabilize or “fix” ultrastructure as it exists under physiological conditions. Ideal fixation and specimen preparation require that the constituents of the system keep their position within a range which is smaller than the resolution of the observation technique. The molecules and ions within a biological specimen interact in very complex ways. The kind of interaction depends strongly on temperature. What type of arrangement or structure is stable at a given temperature is determined by the laws of thermodynamics which state that any system tends towards a state of minimal free energy. The rate at which a system follows this tendency is determined by kinetics. The rearrangement or movement of molecules which is necessary to adapt a system to a change in temperature is usually an activated process, meaning that the molecules involved need excess energy (activation energy) in order to be able to change their positions. This “activation energy” is released after the event has taken place. Molecules which are not at the activated energy level will not react, although the reaction would result in a gain of stability. The pool out of which the activation energy is taken is the thermal energy of the system. Thus, the probability that a molecule is activated in a given time increases with temperature. As a result, a change of temperature has a dual influence on a specimen: it determines the equilibrium or stable structure at the new temperature and also the speed or rate at which the system adjusts to the new equilibrium state.

Apparatus for thermal treatment of a wafer in an evacuated environment

Abstract: In a vacuum chamber wafer treating apparatus, a wafer is heated or cooled by introducing a gas at a pressure of approximately 100 to 1000 microns in a region between the wafer and a heating element or heat sink. The gas conducts thermal energy between the wafer and heating element or heat sink.

Spectroscopic studies of plasma during cw laser gas heating in flowing argon

Abstract: cw laser gas heating in flowing argon was studied using emission spectroscopy. The local electron temperature was calculated from the 415.8‐nm Ari line spectra ratio to the adjacent continuum emission. The two‐dimensional temperature fields were utilized in the calculation of laser power absorption, beam refraction, radiative losses, and net thermal energy retained by the gas. The experiments were performed over a range of laser powers from 2.5 to 6.4 kW and flow velocities between 15 and 120 cm/s. The plasmas were determined to absorb as much as 78% of the incident laser energy at high powers and low flowrates. The calculations indicate that thermal energy retained by the gas is in excess of 35% of the incident energy at intermediate power levels and high flowrates. The results compare favorably with independent calorimetric and thermometric measurements as well as a numerical model. The primary conclusion is that laser propulsion appears feasible in that the earlier dynamic concerns have been shown to be nonexistent or circumventable.

Condensation heat transfer in the presence of noncondensables

Abstract: The effect of noncondensables upon the laminar film condensation of vapor-gas flow inside a horizontal tube were investigated. The analysis was undertaken for the continuity, momentum and the thermal energy with its boundary conditions for the condensable film. Also the diffusion equation with its boundary conditions for the gas phase. The resulting partial differential equations were solved numerically by finite difference technique using a computer program for a wide range of parameters. Numerical results were obtained for the heat transfer coefficients with and without noncondensable for a wide range of parameters. It was found from the numerical results that the heat transfer coefficients inside the tube of the horizontal condenser are strongly dependent upon the axial and circumferential position. The noncondensable reduces the heat transfer and these reductions are accentuated at low operating pressures. For small steam velocities, a severe effects of the noncondensables are expected at the back end of the tube.

Continuous thermal energy delivery from a periodically active energy source

Abstract: Continuous thermal energy delivery from a cyclically active thermal energy source having an ON period substantially exceeding an OFF period by passing working fluid through a central working fluid conduit passing through a containment means forming an annular chamber therewith, the annular chamber substantially filled with a liquid-solid phase change thermal energy storage material having a high specific heat in the liquid phase. During insolation, thermal energy superheats the thermal energy storage material and is conducted therethrough to heat the working fluid. During eclipse the superheated thermal energy storage material transmits heat to the working fluid and formation of solid phase of the thermal energy storage material releases heat of fusion adjacent the working fluid conduit for additional supply of heat to the working fluid. A thermal gradient is maintained across the thickness of the thermal energy storage material.

The exchange coefficients for latent and sensible heat flux over lakes: Dependence upon atmospheric stability

Abstract: Components of the energy budget of a small lake were estimated over the autumnal cooling period. Measured values of the stored thermal energy and radiative heating were used to evaluate several bulk formulae for sensible and latent heat transfer. Over 50–100 day intervals, bulk formulae for latent and sensible heat flux without stability corrections were as good as formulae that incorporated such corrections; both satisfactorily reproduced the measured heat storage data. Over shorter (daily to weekly) time-scales, predictions incorporating stability corrections were superior to those without stability corrections. Over daily periods when the atmosphere was nearly neutral or was unstable, a formulation for sensible and latent heat transfer designed for small-scale systems (cooling ponds and reservoirs) agreed closely with the usual large-scale (oceanic) bulk formulations. The corrections for stability in the small-scale formulation are based on laboratory and theoretical studies of free convection; the stability correction in the large-scale formulation uses a bulk Richardson number in a manner consistent with flux-profile theory. Both agreed with the measured data for the unstable and near-neutral cases. Under stable atmospheric conditions (in a daily average sense), both formulations underestimated the measured fluxes

Thermally controllable optical devices and system

Abstract: A system for the thermal control of optical devices in- cludes an optical device having at least one coating of an electrically conductive material formed on a surface in a heat conducting relationship with the material and connected to a controllable current source which passes varying amounts of electrical current through the layer to vary the amount of thermal energy introduced into the device to control its optical response characteristics. The electrically conductive layer or layers can be optically active, that is, function to affect the light energy transmitted into or through the device as well as acting as an electrically conductive thermal element. The use of an electrically conductive coating or coatings allows the rapid and precise control of thermal energy introduced into the device and, accordingly, the rapid and precise control of the optical characteristics of the device as well as providing a thermal interface between the optical device and the ambient environment that is effective to minimize the adverse affects of transient temperature changes occurring in the environment.

Integrating temperature-averaging sensor

Abstract: A temperature sensor comprising a temperature to electrical quantity transducer or array of interconnected transducers in thermal contact with a defined space such as a tank in which a non-isothermal temperature profile exists. Sensor may be arranged with respect to the shape of the space and its profile enabling single output of sensor to represent integral summation of temperature within the space, linearly interpretable for a given space as representing average temperature or thermal energy content of the space.

Turbulence as a contributor to intermediate energy storage during solar flares

Abstract: Turbulence is considered as a method for converting the energy observed as mass motions during the impulsive phase into thermal energy observed during the gradual phase of solar flares. The kinetic energy of the large-scale eddies driven by the upflowing material continuously cascades to smaller scale eddies until viscosity is able to convert it into thermal energy. The general properties of steady state, homogeneous, fluid turbulence is a nonmagnetic plasma and the properties of turbulent decay are reviewed. The time-dependent behavior of the velocities and energies observed by the X-Ray Polychromator (XRP) instrument on the SMM during the November 5, 1980 flare are compared with the properties of turbulence. This study indicates that turbulence may play a role in flare energies and may account for a fraction of the total amount of thermal energy observed during the gradual phase. The rate at which the observed flare velocities decrease is consistent with the decay of turbulent energy but may be too rapid to account for the entire time delay between the impulsive and gradual phases.

Thermoelectric and photoelectric generation device

Abstract: PURPOSE: To upgrade the conversion efficiency from thermal energy to radiation energy and improve its generation efficiency of electricity by lowering the temperature of a combustion exhaust gas and reducing the principal part of sensible heat difference to radiation energy on the upstream side having a low temperature heat receiving body when the combustion exhaust gas passes the inside of a radiator. CONSTITUTION: The radiator 3 made of a porus solid is centered in the thermoelectric and photoelectric generation part and a combustion chamber 19, a vacuum space (or air preheating space) 20, a photoelectric conversion element 5, a reflecting mirror 21, a cooling water path 22 are formed at the periphery of the radiator. The reflection mirror 21 allows a radiation energy having wavelengths which are not absorbed in the photoelectric conversion element 5 to return to the side of the radiator 3 and its radiator 3 is heated and then, heat retaining energy is produced. In other words, when the exhaust gas passes through the radiator 3, the temperature of its exhaust gas is lowered and also the principal part of sensible heat difference is reduced to the upstream side having a low temperature heat receiving body as radiation energy. As a result, the conversion efficiency from partial energy corresponding to the above reduced one to radiation energy is upgraded and the generation efficiency of electricity is improved. COPYRIGHT: (C)1988,JPO&Japio

Overview of metallic materials for heat exchangers for ocean thermal energy conversion systems

Abstract: Candidate materials for use in ocean thermal energy conversion systems, OTECS, heat exchangers include aluminium, Cu-Ni, stainless steel and titanium alloys. These are considered in this review, and their advantages and disadvantages are highlighted and discussed. Aluminium alloys have shortcomings for the anticipated long life span of OTEC heat exchangers; however they may still offer an economic alternative in the form of short-life, disposable units of low initial capital cost. The long-term effects of exposure to ammonia and to erosion pose questions about the suitability of Cu-Ni alloys. Although stainless steel alloys provide a strong challenge for OTECS use, titanium exhibits better seawater performance, has good fabricability, and has an excellent service history in marine environments. These factors, together with current and projected developments promise major savings in materials usage, reduced OTECS structure sizes and increased efficiencies consequent on the use of titanium and its alloys.

Apparatus for the recovery of waste heat contained in the exhaust from dryers of paper machines

Abstract: Method and apparatus for drying paper webs continuously manufactured in paper machines, by the use of process steam produced by a two-substance compression heat pump with a solution-circuit. A portion of the thermal energy needed for the drying process is obtained from process steam produced by the heat pump from the waste heat contained in the moist exhaust air of the paper machine, and another portion from preheated ambient air, which is then used for drying the paper web. The ambient air is preheated by using it to cool the rich solution of the heat pump.

Selection of high temperature thermal energy storage materials for advanced solar dynamic space power systems

Abstract: Under the direction of NASA's Office of Aeronautics and Technology (OAST), the NASA Lewis Research Center has initiated an in-house thermal energy storage program to identify combinations of phase change thermal energy storage media for use with a Brayton and Stirling Advanced Solar Dynamic (ASD) space power system operating between 1070 and 1400 K A study has been initiated to determine suitable combinations of thermal energy storage (TES) phase change materials (PCM) that result in the smallest and lightest weight ASD power system possible To date the heats of fusion of several fluoride salt mixtures with melting points greater than 1025 K have been verified experimentally The study has indicated that these salt systems produce large ASD systems because of their inherent low thermal conductivity and low density It is desirable to have PCMs with high densities and high thermal conductivities Therefore, alternate phase change materials based on metallic alloy systems are also being considered as possible TES candidates for future ASD space power systems

System for preheating water using thermal energy from refrigerant system

Abstract: A preheater system for using thermal energy available in a refrigeration cycle to heat potable water disposes a double-walled coil having an internal vent path within a water filled tank. Superheated refrigerant is passed through the coil downwardly between an inlet and an outlet. Liquid condensed within the coil accumulates in the bottom of a trap from which it is forced upwardly into a receiver tank and then returned to the refrigeration system. If excessive cooling develops, a pressure responsive valve shunts incoming superheated gas into the receiver tank to return to the selected operating range.

Solar installation with combined photon and thermal energy conversion

Abstract: Solar installation whose topside faces the ambient air and insolation, but whose underside is immersed in cooling water, e.g. sea water, and whose topside is provided with semiconductor photoelements for the purpose of converting solar energy (photons), characterised in that in parallel with the above-named conversion of solar energy a second system employs a temperature gradient between the hot topside and water-cooled underside of the solar installation to effect transport of thermal energy in accordance with the temperature gradient from top to bottom. A fraction of this energy flow is converted into electrical energy, and this substantially increases the specific power capability of the solar installation.

Method for destabilizing and destroying foams by thermal energy

Abstract: To destabilize and destroy foams, as are formed, in particular, in chemical and biological processes, thermal energy is introduced into the foam volume and as a result the mechanical strength of the foam is decreased The thermal energy can be transmitted by steam or by a hot gas The foam bubbles burst either during the heat transfer or they can easily and effectively be destroyed mechanically

Analysis of waste heat and its recovery in a cement factory

Abstract: The cement industry is an energy intensive industry. Energy prices necessitate energy efficient systems, i.e. deep consideration of energy conservation and waste-heat recovery must be made. In the present work, a cement industry was examined with respect to thermal energy consumption, losses and the potential of heat saving. The production line investigated involved a cyclone preheater and precalciner prior to the kiln. In carrying out the work, data were obtained from the control room and by direct measurements on the different units. The thermal energy analysis of the system revealed that a considerable amount of fuel heat is dissipated. For recovering the waste heat, it has been proposed to insulate the external surface of the cyclones and ducts in the preheater unit. The optimization study on the insulations indicated that a 2% fuel saving can be achieved with highly viable payback times ranging from 0.07 to 0.72 yr.

High-efficiency heating unit for producing hot water

Abstract: High-efficiency heating unit for producing hot water, which includes in combination a heat pump which exploits the thermal energy of the sun and/or that of the environmental air for heating water or for producing sanitary water, namely warm water, and an electric burner or boiler for possible supplementary heating of the heated water or water preheated by the heat pump and designed either to be supplied to a heating system or for sanitary use

Generating heat and electricity

Abstract: Apparatus and method for generating thermal and electrical energy, in which thermal energy is derived from an internal combustion engine (12) by a flow of coolant and electrical energy is derived from an A.C. generator (14) driven by the engine (12). Outputs required of the apparatus are determined automatically by a control system (50) which monitors the required loads and then adjusts the relative outputs of the engine (12) and generator (14) to optimal levels. Engine speed is variable without affecting the generator output frequency because of e.g. an epicyclic gear train (42) between engine (12) and generator (14). The apparatus may be used in combination with external energy sources, monitoring these and adjusting its own outputs according to efficiency; on a substantial drop in electric power from the external source the system may by automatic override cause maximum output from the electrical generator (14) regardless of the thermal load.

Development of an integrated heat pipe-thermal storage system for a solar receiver

Abstract: The Organic Rankine Cycle (ORC) Solar Dynamic Power System (SDPS) is one of the candidates for Space Station prime power application. In the low earth orbit of the Space Station approximately 34 minutes of the 94-minute orbital period is spent in eclipse with no solar energy input to the power system. For this period the SDPS will use thermal energy storage (TES) material to provide a constant power output. Sundstrand Corporation is developing a ORC-SDPS candidate for the Space Station that uses toluene as the organic fluid and LiOH as the TES material. An integrated heat-pipe thermal storage receiver system is being developed as part of the ORC-SDPS solar receiver. This system incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain the TES canisters within the potassium vapor space with the toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the earth orbit, solar energy is delivered to the heat pipe in the ORC-SDPS receiver cavity. The heat pipe transforms the non-uniform solar flux incident in the heat pipe surface within the receiver cavity to an essentially uniform flux at themore » potassium vapor condensation interface in the heat pipe. During solar insolation, part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the balance stored in the TES units is transferred by the potassium vapor to the toluene heater tube. 3 refs., 8 figs.« less

Apparatus for continuously cooking and/or dehydrating foodstuffs

Abstract: The invention concerns a process and an apparatus for the continuous heat treatment of foodstuffs. Unlike in known cooking or boiling installations with a substantially homogeneous temperature control of the heat carrier in the form of water, a multizone installation comprising preheating, boiling and recooling zones is suggested, through which the foodstuffs to be treated are passed successively. The heat carrier is conducted through the recooling zone in a direction counter to the conveying direction and then, bypassing the boiling zone, is supplied to the preheating zone leading to a temperature rise in the latter due to the thermal energy passing to the heat carrier during the recooling process. The energy demand is covered by the heat supplied to the boiling zone, which also operates in the countercurrent principle with the aid of circulating means.

Heat transfer research for ocean thermal energy conversion

Abstract: In this lecture an overview of the heat- and mass-transfer phenomena of importance in ocean thermal energy conversion (OTEC) is presented with particular emphasis on open-cycle OTEC systems. Also included is a short historical review of OTEC developments in the past century and a comparison of open- and closed-cycle thermodynamics. Finally, results of system analyses, showing the effect of plant size on cost and the near-term potential of using OTEC for combined power production and desalination systems are briefly discussed.

A hydrometeorological, three‐dimensional model of thermal energy releases into environmental media

Abstract: A computer model has been developed to study thermal energy releases into the environment. A typical application of the model is the study of the behaviour of cooling-tower effluent under different weather and operating conditions. The model employs the full three-dimensional transport equations describing the conservation of mass, momentum and energy. The flow is treated as single-phase and the behaviour of any droplets present is calculated indirectly. The model takes into account such hydrometeorological phenomena as the effects of humidity, wind direction and speed, density variations and the presence and precipitation of droplets. Sample results from cooling tower applications are presented and discussed.

Shower installation for utilising heat from waste water

Abstract: The invention relates to a shower installation for effective recovery of heat from shower waste water, preferably in sports and recreation facilities, public health facilities and also sanitary complexes of military buildings, and can be put into practice in a simple way both for reconstructions and for new building projects. The aim and object of the invention consists essentially in that, on the one hand, utilisation of the thermal energy from the shower waste water is achieved at minimum production and material cost and, on the other hand, simple and also maintenance-free technical possibilities for detecting leaks occurring at the heat exchanger are provided. According to the invention, for this purpose a shut-off valve 6 is arranged in the inlet pipe 11 for the cold fresh water K leading to the heat exchanger 2 in such a way that, both when the shower is in use and not in use, only a low static pressure load and gravitational pressure load is exerted on the heat exchanger 2. In addition, a monitoring or signalling device 17 with a visual display possibility for leaks resulting at the heat exchanger 2 is integrated in the flow region between the shut-off valve 6 and the shower head 4 in which no further shut-off member is installed.