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[en] Under NASA's Project Prometheus, the Nuclear Space Power Systems Program, the Jet Propulsion Laboratory, Pratt and Whitney Rocketdyne, and Teledyne Energy Systems have teamed with a number of universities, under the Segmented Thermoelectric Multicouple Converter (STMC) Task, to develop the next generation of advanced thermoelectric converters for space reactor power systems. Work on the STMC converter assembly has progressed to the point where the lower temperature stage of the segmented multicouple converter assembly is ready for laboratory testing, and promising candidates for the upper stage materials have been identified and their properties are being characterized. One aspect of the program involves mission application studies to help define the potential benefits from the use of these STMC technologies for designated NASA missions such as a lunar base power station where kilowatts of power would be required to maintain a permanent manned presence on the surface of the moon. A modular 50 kWe thermoelectric power station concept was developed to address a specific set of requirements developed for this particular mission concept. Previous lunar lander concepts had proposed the use of lunar regolith as in-situ radiation shielding material for a reactor power station with a one kilometer exclusion zone radius to minimize astronaut radiation dose rate levels. In the present concept, we will examine the benefits and requirements for a hermetically-sealed reactor thermoelectric power station module suspended within a man-made lunar surface cavity. The concept appears to maximize the shielding capabilities of the lunar regolith while minimizing its handling requirements. Both thermal and nuclear radiation levels from operation of the station, at its 100-m exclusion zone radius, were evaluated and found to be acceptable. Site preparation activities are reviewed as well as transport issues for this concept. The goal of the study was to review the entire life cycle of the unit to assess its technical problems and technology needs in all areas to support the development, deployment, operation and disposal of the unit
[en] The thermal collector with varied glass covers represents an innovation realized in order to build a collector able to reach the desired temperature by collecting the solar radiation from the smallest surface, with the highest efficiency. In the case of the thermal collector with variable cover glasses, the number of the glass plates covering the absorber increases together with the length of the circulation pipe for the working fluid. The thermal collector with varied glass covers compared to the conventional collector better meet user requirements because: for the same temperature increase, has the collecting area smaller; for the same collection area, realizes the highest temperature increase and has the highest efficiency. This works is addressed to researchers in the solar energy and to engineers responsible with air-conditioning systems design or industrial and agricultural products drying.
[en] This paper explores the possibility of utilizing the Sodium Heat Engine (SHE) or known as AMTEC (Alkali Metal Thermoelectric Converter), for electrical power generation in ''near earth'' geosynchronous orbit. The Sodium Heat Engine principle is very flexible and adapts well to a variety of physical geometries. The proposed system can be easily folded and then deployed into orbit without the need for on site assembly in space. Electric power generated from SHE engine can be used in communication satellites, in space station, and other applications such as electrical recharging of vehicles in space is one of the applications the Sodium Heat Engine could be adapted to serve. copyright 1995 American Institute of Physics
[en] Three years ago it was presented in these proceedings the relativistic dynamics of a multi-fluid system together with various applications to a set of topical problems . In this talk, I will start from such dynamics and present a covariant formulation of relativistic thermodynamics which provides us with a causal constitutive equation for the propagation of heat in a relativistic setting
[en] One of the fundamental needs for Mars colonization is an abundant source of energy. The total energy system will probably use a mixture of sources based on solar energy, fuel cells, and nuclear energy. Here we concentrate on the possibility of developing a distributed system employing several unique new types of nuclear energy sources, specifically small fusion devices using inertial electrostatic confinement and portable 'battery type' proton reaction cells
[en] A study was performed to quantify the performance of solar thermal power systems for deep space planetary missions. The study incorporated projected advances in solar concentrator and energy conversion technologies. These technologies included inflatable structures, lightweight primary concentrators, high efficiency secondary concentrators, and high efficiency Stirling convertors. Analyses were performed to determine the mass and deployed area of multihundred watt solar thermal power systems for missions out to 40 astronomical units. Emphasis was given to system optimization, parametric sensitivity analyses, and concentrator configuration comparisons. The results indicated that solar thermal power systems are a competitive alternative to radioisotope systems out to 10 astronomical units without the cost or safety implications associated with nuclear sources
[en] Energy fluctuations in a single classical degree of freedom above the ground state at thermodynamic equilibrium at temperature T are typically of average magnitude ∼kBT. However, we show that the average magnitude of such fluctuations can be much larger (or much smaller) than kBT, indeed, that at least in principle it can be infinite (or arbitrarily close to 0). Nevertheless, the average energy fluctuation magnitude being untypically large (or untypically small) does not violate the second law of thermodynamics. For, if the average magnitude of energy fluctuations is much larger than kBT, then particle motion along the degree of freedom must manifest extreme spatial delocalization. The cost of locating the fluctuating particle along its degree of freedom equals or exceeds the large energy gain obtained upon finding it with an energy of much more than kBT above its ground state. The particle loses as much or more ability to do work via its spatial delocalization than it gains via the energy fluctuation. Similarly, if the average magnitude of energy fluctuations is much smaller than kBT, then the small energy yield obtainable upon locating the particle is compensated for by the small cost of locating it.
[en] Thermionics space power systems have been proposed as advanced power sources for future space missions that require electrical power levels significantly above the capabilities of current space power systems. The Defense Special Weapons Agency's (DSWA) Thermionic Evaluation Facility (TEF) is carrying out both experimental and analytical research to advance thermionic space power technology to meet this expected need. A Modeling and Analysis (M and A) project has been created at the TEF to develop analysis tools, evaluate concepts, and guide research. M and A activities are closely linked to the TEF experimental program, providing experiment support and using experimental data to validate models. A planning exercise has been completed for the M and A project, and a strategy for implementation was developed. All M and A activities will build on a framework provided by a system performance model for a baseline Thermionic Fuel Element (TFE) concept. The system model is composed of sub-models for each of the system components and sub-systems. Additional thermionic component options and model improvements will continue to be incorporated in the basic system model during the course of the program. All tasks are organized into four focus areas: 1) system models, 2) thermionic research, 3) alternative concepts, and 4) documentation and integration. The M and A project will provide a solid framework for future thermionic system development
[en] A theoretical study of the dynamics of photo-electron transfer reactions in the Marcus inverted regime is presented. This study is motivated partly by the recent proposal of Barbara et al. (J. Phys. Chem. 96, 3728, 1991) that a minimal model of an electron transfer reaction should consist of a polar solvent mode (X), a low frequency vibrational mode (Q) and one high frequency mode (q). Interplay between these modes may be responsible for the crossover observed in the dynamics from a solvent controlled to a vibrational controlled electron transfer. The following results have been obtained. (i) In the case of slowly relaxing solvents, the proximity of the point of excitation to an effective sink on the excited surface is critical in determining the decay of the reactant population. This is because the Franck-Condon overlap between the reactant ground and the product excited states decreases rapidly with increase in the quantum number of the product vibrational state. (ii) Non-exponential solvation dynamics has an important effect in determining the rates of electron transfer. Especially, a biphasic solvation and a large coupling between the reactant and the product states both may be needed to explain the experimental results
[en] All electronic components which exhibit electrical conductor resistance, generates heat when electricity is passed (Joule - Lenz’s Law). The generated heat is necessary to take into surrounding environment. To reduce the operating temperature of electronic components are used various types of cooling in electronic devices. The released heat is removed from the outside of the device in several ways, either alone or in combination. Intensification of cooling electronic components is in the use of heat transfer through phase changes. From the structural point of view it is important to create a cooling system which would be able to drain the waste heat converter for each mode of operation device. Another important criterion is the reliability of the cooling, and it is appropriate to choose cooling system, which would not contain moving elements. In this article, the issue tackled by the phase change in the heat pipe.