Showing papers on "Thermal reservoir published in 1978"

Heat exchange method and device therefor for thermal energy storage

Abstract: A heat exchange device for the introduction of thermal energy into and removal of thermal energy from liquid-solid phase change material is described in which the phase change material is maintained in a container, which is slowly rotated about a generally horizontal axis at a substantially constant rotational speed. Means are provided for automatically nucleating the phase change material as required for cyclic operation. The invention is of particular utility in the use of incongruently melting hydrates for the storage of thermal energy.

Heat storage apparatus and method

Abstract: A heat storage apparatus and method including a heat storage medium encapsulated within a container and heat exchange apparatus for exchanging thermal energy with the heat storage medium. The heat storage medium may include a salt having a relatively high latent heat of reaction at a relatively low temperature range. The dehydration reaction of sodium sulfate decahydrate appears to the most promising reaction for this application. Other suitable salts and salt mixtures for other temperature ranges may also be used. The apparatus includes, where necessary, techniques for stirring the heat storage medium to inhibit stratification of the salt during cycles of dissolution and recrystallization or fusion.

Thermal storage reservoirs

Abstract: A thermal storage system for use with a solar collector and/or heat pump includes a plurality of discrete heat reservoirs having regular geometric shapes such as spheres or cylinders for forming a self-sorting array of the reservoirs when stacked in a storage bin. Each reservoir has a shell formed of heat conductive material defining an interior cavity that contains a material of high specific heat for storing heat in the reservoir. A preferred material for economy for reservoir shells in spherelike shapes is plastic with heat conductivity enhancers such as glass or metal particles incorporated into the plastic.

Meager Mountain, B. C. : a possible geothermal energy resource

Abstract: A synopsis of the regional and local geology and data on the natural hot springs and their local environment is presented, as well as downhole temperatures and thermal conductivity of core samples from six boreholes. The corresponding heat flows are discussed and an attempt is made to place some physical constraints on the nature of the thermal reservoir. (MHR)

Method of and apparatus for the measuring of quantities of heat

Abstract: A method and apparatus for measuring an unknown quantity of heat in a measuring zone formed by a vessel of good thermal conducting properties is carried out in such a manner that the measuring zone is supplied with a known quantity of heat and the quantity of heat of the measuring zone is given off to a cold zone, that the temperature of the measuring zone is always kept equal to the temperature of the environment and at the same time the dissipation of heat is kept constant by keeping the difference between the temperature of the measuring zone and the temperature of the cold zone always the same, and that the known quantity of heat supplied to the measuring zone is measured at a point outside of the vessel when the unknown quantity of heat is absent and when it is present, the difference between the known quantity of heat in the absence of the unknown quantity of heat on the one hand and the known quantity of heat in the presence of the unknown quantity of heat on the other hand being the measurement result for the unknown quantity of heat. The vessel includes a known heat source and a cold source is provided which is connected with the vessel by way of a heat-conducting element.

Numerical Experiments on Trajectory Instabilities in Dissipative Systems

Abstract: It is confirmed by computer experiments that a probabilistic approach is necessary for description of the dynamics of dissipative systems with unstable trajectories, although given equations of motion are deterministic. How initially close points in phase space do spread with time is examined. From this it is shown that the conditional probabilities can be defined naturally by introducing the concept of coarse graining in phase space and time, and more­ over they satisfy a definition of a Markov process. The effect of external random forces is investigated by adding the Langevin forces to the equations of motion. It is suggested that the statistical properties of unstable dissipative systems are determined mainly by the inherent stochasticity due to the nonlinearity of the systems, unlike equilibrium systems whose statistical properties are governed by external random forces coming from contact with a heat reservoir.

Storage of heat for subsequent use - using reversible chemical reaction with greatly reduced ambient losses

Abstract: The periodic storage and discharge of heat uses at least one heat transformer contg. a working medium. This undergoes an endothermic reversible reaction to give a solid and a gaseous component. In the storage phase, heat is added to the absorber/releaser and the medium yields the gaseous component, which flows into the condenser/evaporator section. Here it condenses releasing heat. In a heat release mode, the condensate in the condenser/evaporator section is evaporated. This then releases heat in the absorber/release zone by reacting with the solid phase which absorbs it. Solar or electric energy can be used as sources of heat. The energy released by condensation is released to atmosphere or to a latent heat store. The heat released during the release mode is used for water heating or space heating. For use in storing solar energy or electrical energy during the night.

Thermal-cycle engine

Abstract: A comparatively low heat differential is utilized for energy generation wherein flow of a fluid from a low temperature reservoir to a high temperature reservoir is maintained by the weight of the fluid, for example through utilization of centrifugal force provided as the vaporized fluid from the high temperature reservoir operates a gas turbine. Evaporation cooling is preferably employed in establishing the temperature differential.

Intermediate temperature, heat storage and retrieval system

Abstract: Energy is stored by heating a salt to a temperature above its latent heat of fusion to convert the salt to a liquid state. Heat is retrieved by moving a heat transfer fluid that is immiscible with the salt and has a density less than that of the salt over the top surface of the liquid salt at such a velocity that the upper layer of the salt is emulsified with the heat transfer fluid to crystallize the salt in the upper layer. Heat is thereby exothermally surrendered to the heat transfer fluid and the crystallized salt gravitates from said top surface, thereby maintaining the top surface in a liquid state. It is preferred to move the heat transfer fluid over the top surface of the salt in either a vortex pattern, or an outward radial pattern. The heat transfer liquid is a liquid selected from the group consisting essentially of THERMINOL, CALORIA SANTOWAX, and di-butyl phthalate.

Heat store using metal hydride, pref. magnesium hydride, as medium - has two heat transfer cycles, minimising useful heat loss

Abstract: Heat store uses metal hydrides (I) as storage substances, which release H2 on taking in heat and liberate heat on recombination of the metal with H2 and a heat transfer medium for conveying the heat to the consumers. Several stages are employed, at least one of which acts as operating stage. The operating stage and consumer or heat source are arranged in a cycle for the heat transfer medium and a second cycle is provided, by which perceptible heat is transferred from stages before the operating stage to later stages. Stores of this type are important in many technical applications, e.g. for balancing load maxima and minima of power stations, overnight storage of heat for heating purposes and storage of solar energy. The store minimises the loss of useful heat and hence of efficiency.

High temperature, heat storage and retrieval system

Abstract: Energy is stored by heating a salt to a temperature above its latent heat of fusion to convert the salt to a liquid state. Heat is retrieved by moving a heat transfer fluid consisting of liquid metal or metals immiscible with the salt, and having a density less than that of the salt, over the top surface of the liquid salt at such a velocity that the upper layer of the salt is emulsified with the heat transfer fluid to crystallize the salt in the upper layer. Heat is thereby exothermally surrendered to the heat transfer fluid and the crystallized salt gravitates from said top surface, thereby maintaining the top surface in a liquid state. It is preferred to move the heat transfer fluid over the top surface of the salt in either a vortex pattern, or an outward radial pattern.

High heating efficiency car heater - operates with heat storage reservoir between heat exchangers to balance intermittent use

Abstract: The high efficiency car heater has a thermal reservoir (18a) which is fitted between the engine powered heat exchanger (5) and the heat exchanger (7) inside the vehicle The reservoir balances out changes in heater demand and provides a more comfortable interior The reservoir can be a phase change type for a high capacity with compact layout and can be joined to the heat exchanges by heat pipes (8a & b)

The information‐theoretic statistical mechanics of a system in contact with a heat reservoir

Abstract: The subject of this paper is the information‐theoretic statistical mechanics of a system in contact with a heat reservoir. The fundamental extremum principle of Jaynes is introduced, and a new essentially thermodynamic characterization of a heat reservoir is established. This allows a new extremum principle—involving a generalization of the Helmholtz free energy of thermodynamics—to be derived. This new extremum principle is used to find that probability distribution which, roughly speaking, best represents a system at fixed temperature. Not unexpectedly, the canonical distribution of Gibbs results. Some consequences of the analysis are discussed. An example of other applications of the new extremum principle is given.

Optical Observation of Adiabatic Magnetization in Rare-Earth Compounds

Abstract: Anomalous population increase of the first excited state of Dy 3+ in Dy 3 Al 5 O 12 in a pulsed magnetic field of a few ms duration is observed optically at 4.2 K. From experiments of the field and time dependences of the population increase, it is concluded that this phenomenon is due to the adiabatic magnetization of an effective-spin system with a large initial splitting. In deriving this conclusion, it is assumed that, during the pulsed field being applied, the spin system is thermally isolated from the heat reservoir but the spin system is in thermal equilibrium because of a fast effective spin-spin relaxation time. The anomalous population increase is also observed in DyAlO 3 , Er 3 Ga 5 O 12 , Ho 3 Al 5 O 12 , HoAlO 3 , but not in TmAlO 3 .

Gas-Kinetic Cooling Processes by Coherent Radiation

Abstract: Recently we have proposed mechanisms by which coherent radiation can be converted, in principle, completely into mechanical work[1,2]. In simplest terms, the method uses: (1) a heat pump process in which radiation of frequency hv 12 = E2 − E1 pumps molecules from an intermediate energy state E1 to a long-lived upper state E2 so that each absorbed photon withdraws an energy E1 from the translational-rotational heat reservoir and stores an energy hv 12 + E1 in the upper state; and (2) as the second step, ultimate release of the energy E2 to heat for the operation of a mechanical engine, the heat rejected being just compensated by that withdrawn in step (1). The process is therefore just the conversion of one type of energy of vanishing entropy into another, ideally, without net heat rejection.

Theory of the temperature stabilization process in gas-controlled heat pipes

Abstract: This paper presents results of an analytical investigation of the temperature-stabilization process in gas-controlled heat pipes. Expressions are obtained for the temperature-sensitivity coefficients.

Thermodynamics of a Non-Equilibrium Quantum System — Resonance Fluorescence

Abstract: The problem of resonance fluorescence from a two-level atom is the subject of intense current research activity [1]. One aspect that has so far received little comment is that it provides a most interesting example of nonequilibrium thermodynamics in a quantum system. Conceptually the situation is simple. The two-level atom is subject to two interactions (a) a coherent interaction with a driving field, (b) an incoherent interaction with a thermal reservoir (spontaneous emission into the radiation field). If the driving field were absent the atom would merely relax into equilibrium with the reservoir and the usual Wigner Weisskopf theory for a damped atom would apply. The effect of the driving field is to maintain the atom away from equilibrium in a new nonequilibrium steady state.

Fabrication and test of a variable conductance heat pipe

Abstract: A variable conductance heat pipe (VCHP) with feedback control was fabricated with a reservoir-condenser volume ratio of 10 and an axially grooved action section. Tests of the heat transport capability were greater than or equal to the analytical predictions for the no gas case. When gas was added, the pipe performance degraded by 18% at zero tilt as was expected. The placement of the reservoir heater and the test fixture cooling fins are believed to have caused a superheated vapor condition in the reservoir. Erroneously high reservoir temperature indications resulted from this condition. The observed temperature gradients in the reservoir lend support to this theory. The net result was higher than predicted reservoir temperatures. Also, significant increases in minimum heat load resulted for controller set point temperatures higher than 0 C. At 30 C, control within the tolerance band was maintained, but high reservoir heater power was required. Analyses showed that control is not possible for reasonably low reservoir heater power. This is supported by the observation of a significant reservoir heat leak through the condenser.