Showing papers on "Heat capacity rate published in 1974"

Method of converting low-grade heat energy to useful mechanical power

Abstract: Specifically disclosed is a method of operating a vapor cycle engine wherein a vaporizable fluid is circulated in a closed loop serially through a first heat source, a second heat source, an expansion vapor engine, a condenser, and back to the first heat source. The method of operation specifically comprises the steps of heating the fluid in the first heat source to a relatively low temperature t, super-heating the fluid in the second heat source to a temperature T, passing the fluid through the expansion vapor engine and then exhausting the fluid from the engine at a temperature T 2 which is greater than the temperature t. Also disclosed is apparatus for specifically accomplishing the method as disclosed.

Thermoelectric power system

Abstract: A thermoelectric power system particularly adaptable for use in outer space in which a nuclear reactor heats a working fluid, which in turn supplies heat to a plurality of thermoelectric generators spaced about a ring-shaped support. A first heat pipe is employed to couple heat between the hot fluid and hot junction of the thermoelectric element of each generator, and a second heat pipe couples heat away from the cold junction of each thermoelectric element. Each of the second heat pipes are elongated flexible units adapted to be folded upon launch of the system of a space vehicle and thereafter extended in space to provide a substantial area of radiation of heat to be discharged.

Hybrid cycle power plant with heat accumulator for storing heat exchange fluid transferring heat between cycles

Abstract: Installation for producing motive power, operating on a hybrid cycle of gas and vapor such as steam. The installation has a heat accumulator for storing a heat-exchange fluid which can also act as a fluid fuel for a heat source adapted to heat the fluid of the heat accumulator. Heat can be drawn from the accumulator in the form of a flow of hot fluid, for use as required by a motive power producing machine which may be a vapor turbine. Fluid can also be drawn from the accumulator, to act as a fuel for the heat source, supplementary fluid being supplied to the accumulator to make up for the amount drawn off, whereby the accumulator contents are continuously renewed, to reduce thermal decomposition of the fluid fuel. The heat source can be a gas turbine for producing a basic power output, the turbine exhaust gases being used to heat the heat-exchange fluid by way of a heatexchanger connected to the heat accumulator. The installation can be used in a station for generating an electrical power supply for a distribution network with fluctuating power demands.

Power generation from hot brines

Abstract: Hot fluid which may contain salts and other dissolved minerals is passed through a direct contact heat exchanger in heat exchange relationship with a working fluid that has a specific gravity sufficiently below the specific gravity of the fluid so that it may pass from the bottom to the top of the heat exchanger chamber in contact with the fluid The pressure of the chamber is selected to provide a certain mixture of working fluid and hot fluid at the output of the power extracting device of the system The working fluid is selected so that the salts and other minerals in the fluid are relatively insoluble therein The working fluid is vaporized in the exchanger and the vaporized working fluid and any steam mixed therewith are passed through a power extracting gas expansion device The working fluid is separately condensed and recirculated

Control of temperature profile across a heat exchanger

Abstract: The temperature profile established across a heat exchanger, such as employed on an extrusion die, for example, is controlled by introducing fluid into the heat exchanger at a predetermined temperature. The temperature of the fluid withdrawn from the heat exchanger is measured, and the rate of flow of fluid through the heat exchanger is controlled in response to the measured temperature to maintain the measured temperature at a predetermined value.

Method of and apparatus for coordinating the application of heat to a melt from sources above and below the melt surface

Abstract: Heat softenable material, typically glass, is heated in a furnace from above its surface, as by fossil fuel burners, and below its surface, as by Joule effect heating by electrical current flowing between electrodes immersed in the melt where predetermined relationships of the amount of heat supplied from each source is automatically established. One form of coordinated control employs ratio control where the relationship of fossil fuel burner heat supplied is maintained in constant proportion to the Joule effect heat supplied. Melter temperature is a primary control for a combustion air supply. A combustion air-fossil fuel ratio controller proportionally controls Joule effect heat applied in one embodiment. In other embodiments the electrical controller provides the master signal to a combustion air control proportionate to the requisite change of heat input dictated, or the combustion air control issues a ratio signal to the electrical controller for proportional changes.

Apparatus for the determination of the thermal efficiency of chemical reactions

Abstract: An apparatus for determining the thermal efficiency of a chemical reaction wherein a reaction vessel is equipped with a double-wall jacket or shell which forms a heat exchanger, a heat transfer fluid medium is circulated so rapidly that the difference of its temperature at the inlet and at the outlet of the shell throughout the entire duration of the reaction, with the exception of possibly occurring momentary irregularities in the reaction kinetics, does not exceed 1° C. A temperature regulator is provided which is constructed as a mixture regulator and encompasses a respective container for heat transfer fluids which are hotter and colder with respect to the temperature of the heat transfer fluid which is circulated in the circulation system and each such container is operatively connected with the circulation system as a function of the reference value deviation of the temperature of the reaction mixture. Further, there is provided an apparatus for the continuous determination of the difference between the temperatures of the reaction mixture and the heat transfer fluid at a randomly selected location of the heat exchanger.

External combustion engine and engine cycle

Abstract: An engine, particularly adapted for use in automobiles, in which ambient air is compressed in a positive displacement compressor and then heated in a heat exchanger. The heat exchanger output drives a rotary turbine which, in turn, drives the positive displacement compressor and produces output power. Any source of heat, such as the combustion products from a fuel burning chamber, may be used to apply heat to the heat exchanger. A heat storage device is also incorporated into the system to provide power during sudden turbine demands.

Heat generator of the combustion product condensation type and process for heating a heat-carrying fluid

Abstract: A heat generator of the type condensing the combustion products of a liquid or gaseous hydrogen fuel suitable for the heating of a heat-bearing fluid, including a tank containing at the top a zone of direct contact between the heat-bearing fluid and the combustion products, a collector for the heat-bearing fluid coming from the zone of direct contact, a convection heat exchanger arranged in the path of the combustion products, a combustion zone at a pressure close to atmospheric pressure, and a conduit which connects the collector of the heat-bearing fluid to the convection heat exchanger and is provided with a pump for replacing under pressure the portion of the heat-bearing fluid coming from the collector and intended to pass through the convection heat exchanger.

Geothermal heat recovery by multiple flashing

Abstract: Hot fluid which may contain salts and other dissolved minerals as well as some fixed gases and especially hot water from a geothermal well is passed through successive flash chambers operating at progressively lower temperatures and pressures. Some of the flash chambers may operate below atmospheric pressure. The steam from each flash chamber is passed in heat exchange relationship with a working fluid to superheat the working fluid. The working fluid operating in a closed loop after being heated is expanded in a power extracting gas expansion device for the generation of power. The fixed gases or non-condensible gases are removed at the output of the highest temperature heat exchanger and released to the atmosphere or passed through a prime mover to recover additional power. The hot fluid at the output of each heat exchanger is either combined with the steam at the output of the next flash chamber and passed through the next heat exchanger or applied to the input of the next flash chamber in conjunction with the hot fluid that is not converted to steam from the preceding flash chamber.

Turbulent heat transfer prediction method for application to scramjet engines

Abstract: An integral method for predicting boundary layer development in turbulent flow regions on two-dimensional or axisymmetric bodies was developed. The method has the capability of approximating nonequilibrium velocity profiles as well as the local surface friction in the presence of a pressure gradient. An approach was developed for the problem of predicting the heat transfer in a turbulent boundary layer in the presence of a high pressure gradient. The solution was derived with particular emphasis on its applicability to supersonic combustion; thus, the effects of real gas flows were included. The resulting integrodifferential boundary layer method permits the estimation of cooling reguirements for scramjet engines. Theoretical heat transfer results are compared with experimental combustor and noncombustor heat transfer data. The heat transfer method was used in the development of engine design concepts which will produce an engine with reduced cooling requirements. The Langley scramjet engine module was designed by utilizing these design concepts and this engine design is discussed along with its corresponding cooling requirements. The heat transfer method was also used to develop a combustor cooling correlation for a combustor whose local properties are computed one dimensionally by assuming a linear area variation and a given heat release schedule.

Winter-regime surface heat loss from heated streams. Research report

Abstract: Evaluation of the rate of surface heat exchange between the water and air has become very significant because of the need to determine the thermal response of streams to heat inputs. The different mechanisms of heat exchange that contribute to the total heat exchange were discussed and the various empirical formular to compute each of the components, as developed by various investigators, were presented and discussed. The suitability of each empirical formula was examined. The methods to linearize the total heat exchange rate were reviewed and a new linearized relation was proposed. General equations, suitable for winter-regime conditions, were presented to compute the coefficients of the linearized heat loss model. (GRA)

Heat transfer interface between a high temperature heat source and a heat sink

Abstract: A heat-transfer interface between and separating a high temperature heat source and a heat sink is formed by the adjacent walls of the heat source and heat sink with a thin gap between these walls and helium gas sealed in the gap, the walls preferably defining concentric hemispheres; this interface being particularly feasible as separable walls of the heater portion of a Stirling engine and a heat source.

On the diurnal heat balance and temperature cycle of natural streams

Abstract: A theory is developed predicting the daily temperature cycle of natural streams. It is shown that for given external parameters, including heat exchange with the streambed, an equilibrium state can be defined which consists of a daily mean temperature, an amplitude and a time lag of the temperature cycle with respect to the net heat flux. Moreover, in the non-equilibrium part of the stream these properties are given as functions of distance from the source. The results, derived analytically, agree well with those obtained numerically by Eckel and Reuter [2]. Lastly the exact shape of the diurnal temperature cycle is calculated by means of a Fourier development of the daily heat flux, producing the wellknown asymmetry of the temperature curve.

Control system for vapor engines

Abstract: The control system hereof is for external combustion vapor engines. The vapor is superheated, and by the control system is maintained at substantially predetermined pressure and temperature for the output power expander, such as a turbine. The mass of the vapor supplied to the expander is proportional to power demand. The vapor is generated in a boiler that is fired by a combustor. Generation of the required vapor is under the control of both the heat rate to the boiler, as well as the rate that liquid is supplied to it. The heating rate is determined in direct response to the fall and/or rise of the pressure of the vapor from its rated level. The feedwater rate is in response to both the said heating rate, as well as to fall and/or rise of the vapor temperature from its rated level.

Low-voltage triode sputtering and backsputtering with a confined plasma: Part IV. Heat transfer characteristics

Abstract: A theoretical and experimental investigation of the heat transfer processes encountered in sputtering and backsputtering systems have led to a method of cooling which does not involve clamping a wafer or substrate to a liquid cooled holder. The basic philosophy of the new method is to take full advantage of radiative cooling of the wafer by: (a) designing the holder so that the wafer has an unobstructed view of the water-cooled bell jar and is thermally isolated from the holder; (b) increasing the emittance of the side of the wafer facing the bell jar by the application of a black body coating. In addition to the above two modes, it is shown that tilting the wafer from a horizontal plane up to 45 °, although introduced primarily to reduce step problems, results in a decreased heating rate and subsequent lower wafer temperatures. Whether one would use one, two, or all three modes depends upon the heating rate (sputtering or backsputtering level), and the maximum temperature the wafer could stand without device damage. For example, if one does not wish to exceed 250 °C in a backsputtered silicon wafer, and at the same time it is desired to maximize the backsputtering rate, then, by employing a properly designed holder, tilted at 45 ° with the top side of the silicon of a black body, one could backsputter at a level corresponding to a heating rate of 0.6 W/ cm2. This corresponds, conservatively, to a removal rate of gold of 2500 A/min. Design curves are presented which permit the prediction of steady state silicon wafer temperatures as a function of heat rate and silicon top side emittance. These theoretical predictions are corroborated by experiments. This study indicates that much of the present sputtering and backsputtering of silicon wafers can be accomplished without clamping the wafer to a liquid-cooled holder.

Semiconductor contg capillary structure for coolant circulation - from source of loss heat to heat sink, giving efficient cooling

Abstract: In a semiconductor device with a semiconductor and a cooling element for transferring loss heat from a heat source in the semiconductor to a heat sink, using circulating coolant, the semiconductor contains a capillary structure, through which the coolant flows to the heat source and is incorporating (partly) in a closed system connected to the heat sink. This arrangement is more efficient than others depending on convection, e.g. (built-in) heat pipe structures. It satisfies both the hgih electrical and the space- and weight-saving requirements.

New concepts for heat exchanger performance

Abstract: It is shown that heat exchangers may have an efficiency and a new effectiveness (which is not the same thing as the traditional effectiveness, although directly related), which are compatible in principle with those already in use to describe heat transfer at extended surfaces such as fins.-The use of the new effectiveness produces the more reasonable result that for maximum new effectiveness the thermal capacity rates of the fluids should be equal, and the disadvantage of parallel flow is more clearly shown.-The use of efficiency has advantages where thermodynamically small (i. e. low NTU) heat exchangers are used.-The meaning of NTU is discussed and several interpretations are given, including consideration of NTU as a modified Stanton number.

General problems of heat exchange in a moving layer

Abstract: An approximate analytical solution is obtained for the problem of steady heat exchange in a moving layer in the presence of heat and mass sources in the gas stream. A numerical-analytical method is developed for the solution of the problem of nonsteady heat exchange of a layer by convection or radiation with the simultaneous action of different disturbing factors.