Showing papers on "Thermal energy published in 1973"

Hydrogen: Its Future Role in the Nation's Energy Economy.

Abstract: In examining the potential role of hydrogen in the energy economy of the future, we take an optimistic view. All the technology required for implementation is feasible but a great deal of development and refinement is necessary. A pessimistic approach would obviously discourage further thinking about an important and perhaps the most reasonable alternative for the future. We have considered a limited number of alternative energy systems involving hydrogen and have shown that hydrogen could be a viable secondary source of energy derived from nuclear power; for the immediate future, hydrogen could be derived from coal. A hydrogen supply system could have greater flexibility and be competitive with a more conventional all-electric delivery system. Technological improvements could make hydrogen as an energy source an economic reality. The systems examined in this article show how hydrogen can serve as a general-purpose fuel for residential and automotive applications. Aside from being a source of heat and motive power, hydrogen could also supply the electrical needs of the household via fuel cells (19), turbines, or conventional "total energy systems." The total cost of energy to a residence supplied with hydrogen fuel depends on the ratio of the requirements for direct fuel use to the requirements for electrical use. A greater direct use of hydrogen as a fuel without conversion to electricity reduces the overall cost of energy supplied to the household because of the greater expense of electrical transmission and distribution. Hydrogen fuel is especially attractive for use in domestic residential applications where the bulk of the energy requirement is for thermal energy. Although a considerable amount of research is required before any hydrogen energy delivery system can be implemented, the necessary developments are within the capability of present-day technology and the system could be made attractive economically .Techniques for producing hydrogen from water by electrolysis, from coal, and directly from thermal energy could be found that are less expensive than those now available; inexpensive fuel cells could be developed, and high-temperature turbines could be used for the efficient conversion of hydrogen (and oxygen) to electricity. The use of hydrogen as an automotive fuel would be a key factor in the development of a hydrogen energy economy, and safe storage techniques for carrying sufficient quantities of hydrogen in automotive systems can certainly be developed. The use of hydrogen in automobiles would significantly reduce urban pollution because the dispersed fossil fuel emissions would be replaced by radioactive wastes generated at large central stations. The conversion of internal or external combustion engines for combustion of hydrogen fuel would probably have less economic impact on the automotive industry than the mass introduction of electric automobiles. However, this is a subject that requires more detailed study. All of the safety aspects of hydrogen utilization will have to be examined, especially the problems of safety in the domestic use and the long distance transport of hydrogen in pipelines at high pressures. It is our opinion that the various energy planning agencies should now begin to outline the mode of implementing hydrogen energy delivery systems in the energy economy. The initial transition to hydrogen energy derived from available fossil fuels such as coal should be considered together with the long range view of all the hydrogen being derived eventually from nuclear energy. By the year 1985 when petroleum imports may be in excess of the domestic supply, these plans could set the stage for the transition period from fossil to a predominantly nuclear energy economy able to supply abundant synthetic fuels such as hydrogen. Synthetic fuels will obviously be more expensive than fuels now derived from petroleum; however, there may be no other viable choice. Thus, it is essential that the analysis and technological feasibility of a hydrogen energy system be considered now. It is of vital importance to the nation to develop some general-purpose fuel that can be Produced from a variety of domestic energy sources and reduce our dependence on imported oil.

Air conditioning apparatus and method

Abstract: Efficiency of an open-cycle air conditioning apparatus and method for heating and cooling is improved and the economy of external power is increased both with respect to cost and energy consumption by providing a combination of a primary heater and a secondary heater for heating the regeneration stream for regenerating the desiccant means in the air conditioning apparatus. The thermal source for the primary heater may utilize waste heat or solar energy which is transferred to a solid phase thermal storage means by a gaseous phase heat exchange medium. The thermal energy may be transferred from the thermal storage means to the regeneration stream of the open-cycle air conditioning apparatus either directly by passing the air stream over the solid phase thermal storage means or indirectly by passing liquid in an enclosed system through the solid phase thermal storage means and the regeneration stream.

Peak efficiency solar energy powered boiler and superheater

Abstract: A cup-shaped enclosure forms an energy conversion chamber open at one end to a solar energy radiation field which is generally in axial alignment therewith, the conversion field incorporating, in order, from the thermal energy receiver aperture at the open end, a boiler heat exchanger and a superheater heat exchanger, which line the radial wall and the closed end wall of the chamber respectively. A water cooled window at the aperture closes off the aperture end of the conversion chamber and is opaque to infra-red radiation, prevents escape of thermal energy by convection. A frustoconical reflecting surface extends radially outward of the enclosure and away from the window to reflect fringe solar radiation into the chamber. One or more cylindrical superheater heat exchanger coils may protrude axially towards the window from the rear end of the chamber. The frustoconical reflecting surface and the window are cooled by further heat exchangers which preheat the feed water entering the boiler heat exchanger.

Gravitational energy sources in Jupiter

Abstract: Gravitational sources of the intrinsic luminosity of Jupiter are examined in the context of current hydrogen-helium models. When no gravitational separation of matter occurs, the amount of heat which can be released over the remaining lifetime of the planet is necessarily limited by the size of its existing reservoir of thermal energy. This conclusion rests only on the assumption that its interior is relatively cold and degenerate. If gravitational unmixing occurs, the size of the thermal reservoir does not necessarily limit the heat output. If core formation occurs, for example, then the size of the core formed will be a limiting factor. The energy released with the formation of a helium core is computed for Jupiter. A core growth rate, averaged over several billion years, of 20 trillionths of Jupiter's mass per year is required if gravitational separation is to play a significant role in the thermal evolution.

Heat pipe turbo generator

Abstract: The adaptation of a heat pipe as a turbo-generator or other power output device for a reliable, quiet, light-weight high-endurance power source is shown. The device requires input thermal energy from a burner radioisotope (or solar heat) and also forced or natural heat rejection from condenser surfaces. Thermal energy conversion to a suitable power output is accomplished by encapsulating a turbine wheel within a heat pipe shell, located in an appropriately geometrical contoured section. Flow work extracted from the kinetic energy of the vapor flow provides rotary shaft power output. The shaft power can drive an electrical generator, pump, compressor, or similar device, also mounted within the heat pipe shell structure. A completely self-contained enclosed unit is provided which requires only external power connection at attachment terminals.

Thermal energy storage material

Abstract: A thermal energy storage material which is stable at atmospheric temperature and pressure and has a melting point higher than 32°F. is prepared by dissolving a specific class of clathrate forming compounds, such as tetra n-propyl or tetra n-butyl ammonium fluoride, in water to form a substantially solid clathrate. The resultant thermal energy storage material is capable of absorbing heat from or releasing heat to a given region as it transforms between solid and liquid states in response to temperature changes in the region above and below its melting point.

Energy partitioning of gaseous ions in an electric field.

Abstract: The partitioning of ion energy among thermal energy, drift energy, and random-field energy is studied by solution of the Boltzmann equation. An expansion in powers of the square of the electric field strength is obtained by Kihara's method. Numerical calculations for several ion-neutral force laws show that Wannier's constant mean-free-time model gives a reasonable first approximation. The formal extension to multicomponent mixtures is also given. The matrix elements obtained are tabulated, and can be used to study the field dependence of other moments of the ion-distribution function.

Electric soldering iron delivering heat by change of state of a liquid heat transporting medium

Abstract: A soldering device having a hollow and closed soldering element which contains a heat transporting medium. The soldering element is supported in a holder and may be slidably removed therefrom. The holder is also provided with a electric element for providing heat to a first heat transmission wall of the soldering element. The heat transporting medium absorbs thermal energy from the heating element through the first heat transmission wall and changes from the liquid phase into a vapor phase. The vapor supplies the thermal energy to a second heat transmission wall of the soldering element which is at a point of the element forming the soldering place which produces the heat necessary for the soldering operation. The vapor changes back into the liquid phase at the soldering place. A capillary mass of porous material is provided along the inside of the soldering element so that the liquid heat transporting medium can flow back through the porous mass from the second heat transmission wall back to the first heat transmission wall as a result of capillary action.

Self-contained static power system

Abstract: A self-contained static power system is disclosed herein having a tubular thermoelectric generator generally disposed within a housing. An isotopic self-sustaining heat source is thermally coupled to the heat reservoir of the tubular thermoelectric generator to provide the requisite thermal energy necessary for the production of electric power therefrom. A liquid sodium heat pipe cooperates in one embodiment to more efficiently transport the heat from the heat source to the tubular thermoelectric generator to achieve a compact and entirely static power system.

Electrostatically controlled heat shutter

Abstract: A heat transfer assembly for conducting thermal energy includes a hermetically sealed container enclosing a quantity of inert gas such as nitrogen. Two opposed walls of the container have high thermal conducting characteristics while the connecting walls have low thermal conducting characteristics. Electrodes are positioned adjacent the high thermal conducting walls and biased relative to the conducting walls to a corona potential for creating an ionic gas wind which must contact the conducting walls to be neutralized. The contact of the gas molecules permits the maximum thermal energy transfer between the walls. Baffles can be positioned adjacent the electrodes to regulate gas flow between the high thermal conducting surfaces.

Martian thermal boundary layers: Subhourly variations induced by radiative-conductive heat transfer within the dust-laden atmosphere-ground system

Abstract: Radiative-conductive heat transfer has been investigated for the ground-atmosphere system of the planet Mars. The basic goal was the quantitative determination of time dependent vertical distributions of temperature and static stability for Southern-Hemispheric summer season and middle and polar latitudes, for both dust-free and dust-laden atmospheric conditions. The numerical algorithm which models at high spatial and temporal resolution the thermal energy transports in the dual ground-atmosphere system, is based on solution of the applicable heating rate equation, including radiative and molecular-conductive heat transport terms. The two subsystems are coupled by an internal thermal boundary condition applied at the ground-atmosphere interface level. Initial data and input parameters are based on Mariner 4, 6, 7, and 9 measurements and the JPL Mars Scientific Model. Numerical experiments were run for dust-free and dust-laden conditions in the midlatitudes, as well as ice-free and ice-covered polar regions. Representative results and their interpretation are presented. Finally, the theoretical framework of the generalized problem with nonconservative Mie scattering and explicit thermal-convective heat transfer is formulated, and applicable solution algorithms are outlined.

Network density of temperature profile stations and its influence on the accuracy of lake evaporation calculations

Abstract: The accuracy of lake evaporation determined by the energy budget method depends on the precision of measurement of the total thermal energy content of the lake, which in turn is related to the number and distribution of the temperature-measuring points. The number of sampling points to be used should be such that the error in the stored thermal energy is of the same magnitude as the error in the other terms in the energy budget. This problem was studied at Lake Hefner, a 2600-acre off-stream reservoir at Oklahoma City, Oklahoma. Ten evaporation periods of 1-week duration each were included. Stored thermal energy was calculated on the basis of temperature profiles taken at 5-foot depth increments at 19 locations uniformly spaced over the lake. Evaporation was determined by the energy budget method using stored thermal energy calculated on the basis of 1, 5, 11, or 19 temperature profile stations. Analysis showed the optimum number of stations to be 5, or one station per 520 acres. Using only one station resulted in an evaporation error of 8.2% at the deepest point of the lake. Increasing the number of stations from 5 to 19 resulted in an increase of accuracy of evaporation measurement of only 1%.

Device for converting thermal energy into mechanical energy

Abstract: A device for converting thermal energy into mechanical energy including a combustion chamber with air and fuel inlets, a flue gas outlet, and duct means with first and second flow restriction means for mixing a portion of the flue gas into the inlet air, the air flow being directly proportional to the pressure difference across the restriction means, and the flue gas flow being proportional to the square root of the pressure difference across the second restriction means.

Free energy near the critical point of fluids according to the scaling hypothesis

Abstract: A phenomenological equation of state which obeys the scaling hypothesis and gives a good representation of data in the critical region of fluids has been used to calculate the free energy per unit volume. An interpolation formula for the scaled free energy function a(x), which is useful for analytic calculations of thermodynamic functions, is proposed and compared with experimental specific heat and pressure data.

Startup analysis for a high temperature gas loaded heat pipe

Abstract: A model for the rapid startup of a high-temperature gas-loaded heat pipe is presented. A two-dimensional diffusion analysis is used to determine the rate of energy transport by the vapor between the hot and cold zones of the pipe. The vapor transport rate is then incorporated in a simple thermal model of the startup of a radiation-cooled heat pipe. Numerical results for an argon-lithium system show that radial diffusion to the cold wall can produce large vapor flow rates during a rapid startup. The results also show that startup is not initiated until the vapor pressure p sub v in the hot zone reaches a precise value proportional to the initial gas pressure p sub i. Through proper choice of p sub i, startup can be delayed until p sub v is large enough to support a heat-transfer rate sufficient to overcome a thermal load on the heat pipe.

Free Energy of Non-isothermal Systems

Abstract: HERE I draw attention to two thermodynamic functions the validity of which seems to be beyond dispute but the very existence of which is little known. Their importance is almost completely disregarded even though they extend the application of the free-energy concept to all systems, isothermal or not: the familiar free-energy functions of Helmholtz and Gibbs, A and G respectively, are simply special cases of the two more universal functions.

A Review of Nuclear Sources of Non-Fossil Chemical Fuels

Abstract: Energy derived from nuclear sources can be utilized either in the form of high-energy radiation, thermal energy or electrical energy. Each of these energy forms can be employed to produce non-fossil chemical fuels by transformation of available non-fossil substances. As a general definition, available non-fossil fuel substances are all resources other than coal, petroleum, or natural gas. Thus the substances that can serve as raw materials for nuclear-energy conversion to non-fossil chemical fuels are basically the substances found in water, air, and minerals. High-energy radiation from nuclear fission can be utilized either directly as fission-fragment energy in a chemonuclear reactor, or indirectly as neutron, gamma, and beta energy from isotopic sources. Fission-fragment energy is actually the only radiation-energy source that can be generated in sufficient quantity and at low enough cost to be considered for production of fuels. The two basic fuels that can be generated are hydrogen from wate...

G-189A analytical simulation of the integrated waste management--water system using radioisotopes for thermal energy

Abstract: An analytical simulation of the RITE-Integrated Waste Management and Water Recovery System using radioisotopes for thermal energy was prepared for the NASA-Manned Space Flight Center (MSFC). The RITE system is the most advanced concept water-waste management system currently under development and has undergone extended duration testing. It has the capability of disposing of nearly all spacecraft wastes including feces and trash and of recovering water from usual waste water sources: urine, condensate, wash water, etc. All of the process heat normally used in the system is produced from low penalty radioisotope heat sources. The analytical simulation was developed with the G189A computer program. The objective of the simulation was to obtain an analytical simulation which can be used to (1) evaluate the current RITE system steady state and transient performance during normal operating conditions, and also during off normal operating conditions including failure modes; and (2) evaluate the effects of variations in component design parameters and vehicle interface parameters on system performance.

Thermal Versus Optical Transitions

Abstract: A common technique for measuring the difference in energy between the ground state and an excited electronic state is by optical absorption which, of course, gives a measure of this difference, subject to definite restrictions. On the other hand, the process of electron transfer to establish a new ground state at high pressure is a thermal one. As we shall find it useful to relate these processes, it is important to understand their differences. We shall find that in many cases the thermal energy is apparently much smaller than the energy observed optically. We shall show that this is reasonable, and present an approximate relationship between them.

Energy balance for a pulsed D-T reactor

Abstract: The energy flow per pulse of a D-T reactor is considered, including effects of radial and temporal variations of plasma density and temperature. The overall "efficiency" of the cycle will probably be less than twenty per cent, because of the inefficiency of coupling electrical energy into plasma thermal energy. This low overall efficiency and the spatial and temporal effects lead to required products of density and confinement time which are significantly higher than those obtained ignoring these effects.

Preliminary proposal to investigate a new energy source: direct magma tap

Abstract: The conceptual approach of the proposed direct magma tap is to extract thermal energy directly from a local magma source, such as from a large molten lava pocket or cell associated with a volcanic system. Heat would be continually transferred to a collector, possibly consisting of a set of heat pipes. Natural convective flow in the magma cell would circulate the magma around the collectors in such a way that solidified material should settle to the bottom of the chamber. The heat pipes would be connected to a secondary heat exchanger connected to a surface system which could be a conventional steam power generation system. The proposed system would be completely closed so that no leakage of water or other working fluids should occur. The advantages of the direct magma tap in comparison with other earth heat extraction schemes are noted. A list of volcanic magma sources is given. (LBS)