27 research outputs found
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Impacts of research efforts on new and existing buildings
This paper reviews some of the resources for natural heating and cooling of buildings and outlines the potential benefits of specific examples of advanced research. The needs and possibilities for superior glazings, switchable glazings, thermal diodes, thermal transport systems, phase-change material in wallboard, and low-emissivity wall coatings are examined
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Passive space heating with a self-pumping vapor system
In this system, which should be useful for space or water heating, a refrigerant is evaporated in a solar collector and condensed within thermal storage located in the building below the collector. The vapor pressure generated in the collector periodically forces the condensed liquid upward to the location of the collector. This paper reports results of an operational test, in which this system provided passive space heating for an outdoor test cell during a winter season. The daily average energy yield and the elevation of collector temperature caused by self-pumping are reported, as well as observations on failure modes, system reliability, and suggestions for a practical configuration
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Passive vapor transport solar heating systems
In the systems under consideration, refrigerant is evaporated in a solar collector and condensed in thermal storage for space or water heating located within the building at a level below that of the collector. Condensed liquid is lifted to an accumulator above the collector by the vapor pressure generated in the collector. Tests of two systems are described, and it is concluded that one of these systems offers distinct advantages
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Self-pumping vapor system for hybrid space heating
This paper reports investigations of a passive system that transports heat from a solar collector downward. Refrigerant is evaporated in a collector and the vapor transports heat to one or more condensers located at an arbitrary elevation below the collector. The vapor pressure lifts the condensed liquid to an accumulator located near the top of the collector. The results of annual performance calculations are presented for a space heating application in which one or more condensers are located within passive thermal storage units that release heat directly to one or more zones of the building. Simple sizing rules for optimal energy yield are given
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Evaluation of materials by the energy yield of an active system
This paper reviews the energy impact of materials on active systems for hot water and space heating of buildings. The energy impacts of absorbers, heat transfer fluids, and thermal storage materials on active systems are well understood, and are described only briefly. The study of energy impacts of glazings has just begun, and initial results are presented
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Collector research and development
Current solar collector research of the Los Alamos National Laboratory is described. The document is divided into three sections dealing with the three aspects of the program: reliability and maintainability, optical materials, and evacuated tube collector testing
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Efficiency of a solar collector with internal boiling
The behavior of a solar collector with a boiling fluid is analyzed to provide a simple algebraic model for future systems simulations, and to provide guidance for testing. The efficiency equation is developed in a form linear in the difference between inlet and saturation (boiling) temperatures, whereas the expression upon which ASHRAE Standard 109P is based utilizes the difference between inlet and ambient temperatures. The coefficient of the revised linear term is a week function of collector parameters, weather, and subcooling of the working fluid. For a glazed flat-plate collector with metal absorber, the coefficient is effectively constant. Therefore, testing at multiple values of insolation and subcooling, as specified by ASHRAE 109P, should not be necessary for most collectors. The influences of collector properties and operating conditions on efficiency are examined
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Salt-gradient solar ponds
A description of salt-gradient solar ponds is presented. Guidelines concerning the construction and maintenance of the pond are discussed. A computer model was used to study layer migration in laboratory tanks and in an outdoor pond. The status of solar ponds is briefly discussed. An equation relating heat flux and salt flux at a boundary is included. (BCS
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Ventilation of porous media
Methods for distributing gases throughout the interstices of porous materials and removing volatile substances from the interstices of porous materials. Continuous oscillation of pressures and flows results in increased penetration of the interstices by flowing gases and increased transport of gaseous components out of the interstices. The invention is particularly useful in soil vapor extraction
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Soil vapor extraction enhanced by oscillatory flow
The rate of contaminant removal by soil vapor extraction becomes low when diffusion limits the transfer of vapor from the soil to the channels in the soil where air preferentially flows. This paper suggests that adding an oscillatory component to the pressure and velocity of the subsurface air may increase the transport to the channels of flow, and thereby increase the rate of extraction, when the diffusion limit occurs. Three physical mechanisms by which oscillatory flow may increase the transport are described. Algebraic expressions and numerical estimates are given for the penetration of oscillatory pressure into various soils. Exploratory experiments with a laboratory soil column indicate enhanced extraction when an oscillatory component is superimposed upon nonequilibrium steady flow. 30 refs., 4 figs., 2 tabs