Showing papers on "Thermal reservoir published in 1996"

Thermal properties of an inflationary universe.

Abstract: An energetic justification of a thermal component during inflation is given. The thermal component can act as a heat reservoir which induces thermal fluctuations on the inflaton field system. We showed previously that such thermal fluctuations could dominate quantum fluctuations in producing the initial seeds of density perturbations. A Langevin-like rate equation is derived from quantum field theory which describes the production of fluctuations in the inflaton field when acted upon by a simple modeled heat reservoir. In a certain limit this equation is shown to reduce to the standard Langevin equation, which we used to construct "warm inflation" scenarios in previous work. A particle physics interpretation of our system-reservoir model is offered.

Electrical Heating With Horizontal Wells, The Heat Transfer Problem

Abstract: It is desirable to introduce heat into the production system and reservoir of a horizontal well producing heavy oil. An increase in temperature around the wellbore can remove thermally alterable skin effects, increase the productive length of the well, improve pumping efficiency, and reduce the energy requirements to lift the oil to surface. One way to create the heat is to use electricity. The heat transfer problem consists of solving several concurrent mechanisms. The horizontal well is constructed from commercial grade carbon steel pipe which is an electrically conducting ferromagnetic material. Therefore the heat losses within the horizontal well liner are generated by both ohmic, I 2 R and hysteresis effects. Heat is also electrically produced in the reservoir adjacent to the horizontal well by ohmic losses. To further complicate the heat transfer problem, heat is produced from the reservoir with the fluids and conducted from the well by the action of thermal conduction. In summary, the heat transfer problem consists of distributed heat sources in regions where there is current flow, convection, and conduction. The objective of this paper is to present a semi-analytical model that can be used to calculate the temperature distribution along the length of a horizontal well that is being electrically heated. The analytical model can be used to determine a safe operating strategy based upon the resulting temperature distribution for a given operating current and fluid production rate. From the magnitude of the current, the size of the power supply system can be specified and the energy costs for electrically heating a horizontal well can be calculated. It is found that for a long horizontal well, heat transfer to the adjacent reservoir by conduction is more significant than heat transfer by convection and electrical heating. It is also found that the safe operating magnitude of the current in the horizontal well, determined by the allowable temperature rise, is limited by the cooling effect of produced fluids. Also, the energy costs to heat the well are relatively small in comparison to other operating costs.

Applying thermal therapy to living tissue

Abstract: A thermal therapy device for applying temperature controlled therapy to a therapy site on a mammalian body, comprising: a therapy pad for applying a selected therapy temperature to the therapy site; a recirculating fluid loop comprising a fluid channel defined by the therapy pad; a pump for circulating fluid through the recirculating fluid loop; a thermal reservoir; a heat exchanger coupling the thermal reservoir with the recirculating fluid loop; and a control mechanism coupled to the heat exchanger for enabling adjustable control of therapy temperature. The heat exchanger selectively mixes fluid recirculating in the fluid loop with fluid from the thermal reservoir in an adjustable mixing ratio to achieve the selected therapy temperature at the therapy site.

Chapter 3 – the canonical ensemble

Abstract: Publisher Summary This chapter gives a detailed account of canonical ensemble systems and discusses some properties of such a system. The concept of fixed energy, or even an energy range, for a system belonging to the real world does not appear satisfactory because the total energy E of a system is very difficult to accurately measure and it is not possible to keep its value under strict physical control. A better alternative is to speak of a fixed temperature T of the system—a parameter that is not only directly observable but also controllable by keeping the system in contact with an appropriate heat reservoir. If the reservoir consists of an infinitely large number of mental copies of the given system, an ensemble of systems is obtained in which the macrostate of the systems is defined through parameters such as the number of particles (N), the volume (V), and the temperature (T). Such an ensemble is referred to as a “canonical ensemble.” In the canonical ensemble, the energy E of a system is variable and, theoretically, can take values anywhere between zero and infinity. The chapter also discusses the classical systems and gives the significance of the various statistical quantities in the canonical ensemble, along with discussing some properties of paramagnetism and the effect of magnetism on thermodynamics.

Analysis and optimization of a natural draft heat sink system

Abstract: An analytical solution for a system consisting of a vertical, parallel-plate, isothermal heat sink, and a chimney is presented. The result is applied to problems in which the size of the overall system is constrained. A ridge of maximum total heat transfer is observed with respect to the plate spacing and heat-sink height. The ridge suggests that heat-sink height may be reduced without diminishing the thermal performance for natural draft cooling. The flow characteristics of optimal systems reveal that systems with and without chimneys dissipate maximum heat when the velocity profiles within the heat sink are fully developed and developing, respectively.

Heat release rate calorimetry

Abstract: A simple, theoretically sound method for eliminating the effects of internal heat absorption on rate of heat release is described for the Ohio State University (OSU) Release Rate apparatus. By monitoring the temperature of metal walls and calculating the heat loss to surroundings caused by changes in wall temperature due to heat absorption, a complete energy balance on the system allows the calculation of a true heat of release rate.

Two-Phase Cooling Flows with Magnetic Reconnection

Abstract: Motivated by the observations of high Faraday rotation measures measured in cooling flow clusters we propose a model relevant to plasmas with comparable thermal and magnetic pressures. Magnetic field reconnection may play a major role in changing the topology of the magnetic field in the central cooling flow regions. The effect of the topology change is that cool flux loops can reconnect to hot flux loops that are connected to the overall thermal reservoir of the cluster. There can be a rapid recycling of mass between hot and cold phases on a time scale of 3 x 10^8-10^9 yr which may reduce the inferred inflow and mass condensation rates by at least an order of magnitude. A central multiphase medium is a direct consequence of such a model. Throughout the cooling flow the filling factor of the hot loops (T > 2 x 10^7 K) is of order unity. The filling factor of the cool loops (T < 2 x 10^7 K) is 0.1-1% with a corresponding mass fraction of cold phase of 1-10%. A crucial parameter is the coherence length of the field relative to the cooling radius and the distribution of field energy with scale. When the cooling radius is greater than the field coherence length then cooling flows proceed as usual. When the coherence length is greater than the central cooling radius, however, the thermal energy of the reservoir can be tapped and the mass condensation rates may be very significantly reduced. Three additional conditions must be satisfied: I. Cold loops must be able to fall at least as far as the mean distance between hot loops in a cooling time; II. Loops must enter an evaporative phase on reconnecting; and III. A sufficient number of hot loops penetrate the cold phase region to power the radiative losses.

Relaxation of Schrodinger Cat States and Displaced Thermal States in a Density Operator Representation

Abstract: Damping of quantum superposition of displaced states such as a Schrodinger cat state and a displaced thermal state interacting with a thermal reservoir is studied in a density operator formalism. The master equation approach is employed and the solution is shown to be factorized to a thermal density operator and displacement operators. This formalism is applied to the cat generating experiment proposed by Brune et al. [Phys. Rev. A 45 (1992) 5193], and the field evolution is obtained analytically.

Two-Phase Cooling Flows with Magnetic Reconnection

Abstract: Motivated by the observations of high Faraday rotation measures measured in cooling flow clusters we propose a model relevant to plasmas with comparable thermal and magnetic pressures. Magnetic field reconnection may play a major role in changing the topology of the magnetic field in the central cooling flow regions. The effect of the topology change is that cool flux loops can reconnect to hot flux loops that are connected to the overall thermal reservoir of the cluster. There can be a rapid recycling of mass between hot and cold phases on a time scale of 3 x 10^8-10^9 yr which may reduce the inferred inflow and mass condensation rates by at least an order of magnitude. A central multiphase medium is a direct consequence of such a model. Throughout the cooling flow the filling factor of the hot loops (T > 2 x 10^7 K) is of order unity. The filling factor of the cool loops (T < 2 x 10^7 K) is 0.1-1% with a corresponding mass fraction of cold phase of 1-10%. A crucial parameter is the coherence length of the field relative to the cooling radius and the distribution of field energy with scale. When the cooling radius is greater than the field coherence length then cooling flows proceed as usual. When the coherence length is greater than the central cooling radius, however, the thermal energy of the reservoir can be tapped and the mass condensation rates may be very significantly reduced. Three additional conditions must be satisfied: I. Cold loops must be able to fall at least as far as the mean distance between hot loops in a cooling time; II. Loops must enter an evaporative phase on reconnecting; and III. A sufficient number of hot loops penetrate the cold phase region to power the radiative losses.

Heat sink, its manufacture method and package using the same

Abstract: PROBLEM TO BE SOLVED: To provide a heat sink which has high heat conductivity by means of the complex of diamond particles and a metal and which prevents distortion destruction owing to a thermal expansion difference with a mounted semiconductor and to provide the package of high performance through the use of the heat sink. SOLUTION: The heat sink which is the complex where the diamond particles 2 whose average particle diameters are 50μm-800μm and the metal are complexed, and in which the diamond particles 2 are arranged so that heat conductivity and thermal expansion factor in a face direction and a direction vertical to the face differ is provided. When the heat sink is used for the package mounting the semiconductor, the heat radiation of the heat sink increases in the direction perpendicular to the face of the heat sink, and it is used as a high output diode and a power module.

Produce drier system using subtended heat source and heat reservoir

Abstract: An improved dryer and method for drying the surface of produce and other objects. The dryer has a continuous conveyor for transporting the objects in a substantially horizontal path, a heat reservoir disposed beneath the conveyor for radiating heat, and a drying hood assembly for enclosing a volume above the heat reservoir and the continuous conveyor. The drying hood assembly has a hood, air baffles disposed near the conveyor, and a hood fan to facilitate air flow turbulence about the air baffles within the drying hood assembly. A heat source is provided for heating the heat reservoir. A monitoring system is provided for receiving and interpreting sensory readings received from sensors disposed at locations about the dryer. The monitoring system also provides controlling signals to regulate the drying conditions for objects being conveyed. The method for drying objects includes monitoring drying conditions and regulating the amount of heat generated by the heat source, the speed the conveyor moves, and the operation of fans to maintain optimum drying conditions.

Assembly and testing of a composite heat pipe thermal intercept for HTS current leads

Abstract: We are building high temperature superconducting (HTS) current leads for a demonstration HTS high gradient magnetic separation (HGMS) system cooled by a cryocooler. The current leads are entirely conductively cooled. A composite nitrogen heat pipe provides efficient thermal communication, and simultaneously electrical isolation, between the lead and an intermediate temperature heat sink. Data on the thermal and electrical performance of the heat pipe thermal intercept are presented. The electrical isolation of the heat pipe was measured as a function of applied voltage with and without a thermal load across the heat pipe. The results show the electrical isolation with evaporation, condensation and internal circulation taking place in the heat pipe.

Wärmespeicherung mit Salzen und Salzhydraten

Abstract: The economic use of ambient or low temperature heat requires effective thermal energy storage. The heat should be stored at constant temperature only slightly above the user's desired temperature. Latent heat storage satisfies these requirements much better than the usual sensible heat storage in water, and offers in addition much larger storage capacities. This work gives a theoretical introduction to latent heat storage and describes the development of prototype and production models of latent heat storage units for domestic heating and warm water supply.

Device for applying thermal therapy to living tissue

Abstract: A thermal therapy device for applying temperature controlled therapy to a therapy site on a mammalian body, comprising: a therapy pad for applying a selected therapy temperature to the therapy site; a recirculating fluid loop comprising a fluid channel defined by the therapy pad; a pump for circulating fluid through the recirculating fluid loop; a thermal reservoir; a heat exchanger coupling the thermal reservoir with the recirculating fluid loop; and a control mechanism coupled to the heat exchanger for enabling adjustable control of therapy temperature. The heat exchanger selectively mixes fluid recirculating in the fluid loop with fluid from the thermal reservoir in an adjustable mixing ratio to achieve the selected therapy temperature at the therapy site.

Heat accumulating floor heating equipment

Abstract: PURPOSE: To provide space saving heat accumulating floor heating equipment, which is capable of using midnight power more effectively and reducing a running cost and controlling heat emission and burning additionally. CONSTITUTION: This invention relates to heat accumulating floor heating equipment wherein a heat reservoir 2, which is incorporated with a heat accumulating material 1 is laid out on the bottom of a floor surface and the floor is heated by the emission of heat from the heat accumulating material 1. A pipeline 3 is connected to the heat reservoir 2 while hot water is distributed in the heat reservoir 2 where the heat is accumulated. A control unit 8, which comprises an expansion tank, a pump 32, a heat accumulation heater 83 and an additional burning heater 84, is connected to the heat reservoir 2 by way of a pipeline.

Quadrupolar interactions in non-cubic crystal and related extra heat capacities. Possible effects on a sapphire bolometer

Abstract: It is shown that in a non-cubic crystal, the extra heat capacity due to quadrupolar interaction of nuclear spins > 1 2 could be much bigger than the phonon heat capacity when the temperature decreases. The possible coupling between quadrupolar and phonon heat reservoir via paramagnetic impurities is stressed. A NMR experiment done on sapphire is presented with an evaluation of the coupling between the two reservoirs and its consequence on the performance of the bolometer.

A survey of the thermal stability of an active heat sink

Abstract: In cases where forced convective cooling alone is inadequate, or where the size of the housing limits the heat sink's dimensions, IC's can be cooled using an active heat sink. Compared to a classical finned heat sink, it can benefit from a substantial size reduction or from an important enhancement of the heat transport from the IC to its surroundings. The active heat sink's function is based upon a Peltier-effect cooling system. The active heat sink controls the IC's thermal resistance to its surroundings. The Peltier-effect heat pump is a non-linear system. Therefore, surveys of the system's stability are far from evident. Thermo-Electric models for both the Peltier-effect heat pump and a NTCR (Negative Temperature Coefficient Resistance) temperature sensor are presented. These are linked to thermal models for the IC packaging and a finned heat sink on one hand and to electronic models for the controlling circuit on the other hand. Simulations show non-linear thermal behaviour and system instabilities according to the power load on the IC, to the forward amplification of the circuit, but also to the ambient temperature change. The latter phenomenon occurs after power-on of the whole device of which the IC is a part. The theoretical results were confirmed by infrared thermographic measurements on a self constructed active heat sink.

High efficiency thermal reservoir

Abstract: The reservoir converts stored thermal energy back into mechanical and / or electrical energy, and has an insulated reservoir container (1), which is connected by first (6) and second (15) pipes to a heat pump (11) and / or a heat engine (14). It also has at least one container (3) for a storage medium (4,5), which is immersed in the flow of a circulating medium (2).A circulation pump (7) may be arranged in the first and / or second pipe, and the heat pump and heat engine may be connected to the circulation by pipes (9,10), which may also have blocking elements (12,13) in order to switch them in or out of the flow. The elements may be valves, and the storage medium may be such that with a change in temperature, it undergoes a phase transition.

Si-impregnated sic honeycomb structural body and honeycomb-shaped heat storage body using the structure

Abstract: PURPOSE: To provide an Si-impregnated SiC honeycomb structural body which is suitable to constitute a heat reservoir used in a corrosion resistant atmosphere at a high temperature which exceeds a specific temperature and a honeycomb heat reservoir which uses the structural body. CONSTITUTION: An Si-impregnated SiC honeycomb structural body 2 consists of Si-impregnated SiC whose porosity is 3% or less and a wall thickness which is 0.5mm or less. A honeycomb-shaped heat reservoir 1 comprises a plurality of Si-impregnated SiC honeycomb structural bodies 2 which are stacked so that flow passages comprising through holes 3 may be placed side by side in one direction and is designed to collect waste heat by passing waste gas and gas to be heated through the through-holes 3 alternately.

Heat consumption measurement method aimed to compute air conditioning service rate in air conditioning system

Abstract: PURPOSE:To make it possible to compute a fair service rate by measuring the temperature of air prevailing on the upstream side and the downstream side of a heat exchanger of a handing unit having a heat exchanger function and an air supply function and computing the heat consumption of the unit based on a maximum capacity and a rotary speed of an air supply fan. CONSTITUTION:A heating medium, which is water-fed to a feed line 2-1 of a circulation pipe 2, is water-fed to a heat exchanger 3 of a fan coil unit 4 (FCU) or an air handing unit 5 (AHU) installed to each of living rooms A and B and then, the heating medium is arranged to be returned to a heat reservoir 1. In such an air conditioning system as described above, a centralized control unit 13, which controls each of the units 4 and 5 and variable air capacity units (VAU) 11 to 11, computes the feed of a heating value from the AHU 5 on the basin of a differential air temperature between the upstream side and down stream side of the heat exchangers of the AHU 5 and a rotary speed of an air feed fan 8. The feed quantity of heat is divided on the basin of the consumption of air for each VAV, thereby computing the consumption of heat for each VAV.

A finite-time heat engine with fixed-capacity heat transfers

Abstract: We consider a finite-time heat engine in which the temperature T(t) of the working fluid during heat exchanges with the hot and cold reservoirs is determined passively by the heat capacity of the fluid. The set of feasible operations of this engine, whose irreversibility arises solely from the temperature difference between the reservoir(s) and the working fluid, is described in terms of an inequality which sets limits on the rate P of work output and the rate D of entropy production associated with a cycle that takes place in time . Those operations that lie on the boundary of this set are the ones that achieve a specified work output and entropy production in minimum time; this leads naturally to a notion of time efficiency for any operation within the set. The results obtained here extend our previous framework for Carnot-like processes to examine the time efficiency, as well as the power efficiency, of the corresponding Otto- and Brayton-cycle based engines. The present results and the earlier ones can be seen as two extremes of a continuum in which the external control on the temperature of the working fluid varies between (i) passively allowing the T(t) corresponding to a constant heat capacity response and (ii) actively achieving any desired T(t).

On the Entropy Change of Surroundings of Finite and of Infinite Size: From Clausius to Gibbs

Abstract: The entropy variation of finite surroundings induced by a chemical reaction is expressed in terms of the reaction enthalpy and the temperature change of the reacting system and of the variables of the surroundings. Expanding the surroundings to infinite size, the expression can be shown to reduce to the Gibbs equation, corresponding to the completely system-oriented entropy analysis. The reversibly calculated heat exchange of a thermal reservoir just equals the opposite irreversible reaction heat of the system.

Geothermal reservoir at Tatapani Geothermal field, Surguja district, Madhya Pradesh, IN

Abstract: The Tatapani Geothermal field, located on the Son-Narmada mega lineament is one of the most intense geothermal manifestation, with hot spring temperature of 98°c. in Central India. 21 Exploratory and thermal gradient boreholes followed by 5 production wells for proposed 300 KWe binary cycle power plant, have revealed specific reservoir parameters of shallow geothermal reservoir of 110°c in upper 350 m of geothermal system and their possible continuation to deeper reservoir of anticipated temperature of 160 ± 10°c. Testing of five production wells done by Oil and Natural Gas Corporation concurrently with drilling at different depths and also on completion of drilling, have established feeder zones of thermal water at depth of 175-200 m, 280-300 m, maximum temperature of 112.5°c and bottom hole pressure of 42 kg/cm². Further interpretation of temperature and pressure profiles, injection test, well head discharges and chemical analysis data has revealed thermal characteristics of individual production wells and overall configuration of .thermal production zones with their permeability, temperature, and discharge characteristics in the shallow thermal reservoir area. Well testing data and interpretation of reservoir parameters therefrom, for upper 350 m part of geothermal system and possible model of deeper geothermal reservoir at Tatapani have been presented in the paper.

Heat storage device and heat exchanger using the heat storage device

Abstract: PURPOSE: To provide a heat storage device whose shape is easily deformable in conformity with the installation space of a heat exchanger and a heat exchanger which can be installed to a small space. CONSTITUTION: A heat storage device comprises a heat reservoir which is an aggregate of pellet-shaped particles 1a having a heat storage ability comprising amorphous resin and an organic group heat reserving material which is carried by the amorphous resin and phase-transfers reversibly between a solid and a liquid and a flexible tube 2 where the particles la are filled-up. A heat exchanger is provided with a flow passage 4 of a heating medium which is formed around the heat storage device and the tube 2 and placed in contact with the heat storage device and a vessel which houses the tube 2 in a curved state. The other heat exchangers serve as the flow passage 4 for the heating medium which places a cavity between the particles 1a of the heat storage device into contact with the heat reservoir.

A heat engine with unique characteristics

Abstract: A heat engine which operates with one heat reservoir is described. The engine transforms the heat input completely into work by using a compressed fluid from a resource of the environment. For this reason the engine is not a perpetual motion machine of the second kind. The characteristics of the engine are analyzed, and the ways for achieving the most economic use of the compressed fluid are described. The principle of operation of the engine shows that the concepts of phenomenological thermodynamics regarding heat and its transformation in other forms of energy are not true.

Dwelling house provided with snow melting device using solar heat

Abstract: PURPOSE: To remove snow by melting it automatically with a solar heat by covering a snow melting area of the roof of a dwelling house or the like in the arrangement of heat radiating pipes and installing a heat reservoir underground in a site and placing a plurality of vacuum tube type solar heat collectors in the vertical direction one upon the other CONSTITUTION: Solar heat collectors 10 and a heat reservoir 6 are connected with a pipeline 11 and a circulating pump 8 is driven to circulate forcibly hot water 7 by using a solar heat between the solar heat collectors 10 and the heat reservoir 6 so that the hot water may be stored Then, the introduction end 1a of hot water of the heat radiating pipes installed to a snow melting area of a roof A or the like is placed below a setting water level (h) of hot water 7 collected in the heat reservoir 6 while the discharge end 1b of hot water is placed above the setting water level (h) of the hot water 7, thereby forcibly circulating the hot water 7 between the heat radiating pipes 1 and the heat reservoir 6 by means of a circulating pump 8 installed to the introduction end la Then, the hot water 7 is circulated and supplied to the heat radiating pipes 1 which cover each snow melting area, which makes it possible to melt accumulated snow by the emission of heat from the heat radiating pipes 1

Thermal aspects of resistors embedded in dielectrics

Abstract: This note presents a formula for estimating the temperature of a distributed resistor or resistor chain that is immersed in a dielectric medium, which in turn is surrounded by a heat reservoir An example computation from an actual instrument is included