Showing papers on "Solar energy published in 1992"

Endoreversible thermodynamics of solar energy conversion

Abstract: This is a book for every scientist interested in thermodynamics, solar energy, or both. It describes in a very clear and often subtly humoristic way the physical limits governing the conversion of solar energy into work, into wind energy, into electricity, and into chemical substances of high energy level, like carbohydrates. Endoreversible thermodynamics is a subset of irreversible thermodynamics in which thermodynamical losses are restricted to the coupling of an engine and/or reactor to the outside world. The book may serve highly diverse purposes. The scientist, the teacher, the higher level student, and the solar engineer all will find useful information and applications. The author indicates that the book is not a textbook, nor a reference manual but rather it illustrates general principles using idealised models.

Estimating net solar radiation using Landsat Thematic Mapper and digital elevation data

Abstract: A radiative transfer algorithm is combined with digital elevation and satellite reflectance data to model spatial variability in net solar radiation at fine spatial resolution The method is applied to the tall-grass prairie of the 16 x 16 sq km FIFE site (First ISLSCP Field Experiment) of the International Satellite Land Surface Climatology Project Spectral reflectances as measured by the Landsat Thematic Mapper (TM) are corrected for atmospheric and topographic effects using field measurements and accurate 30-m digital elevation data in a detailed model of atmosphere-surface interaction The spectral reflectances are then integrated to produce estimates of surface albedo in the range 03-30 microns This map of albedo is used in an atmospheric and topographic radiative transfer model to produce a map of net solar radiation A map of apparent net solar radiation is also derived using only the TM reflectance data, uncorrected for topography, and the average field-measured downwelling solar irradiance Comparison with field measurements at 10 sites on the prairie shows that the topographically derived radiation map accurately captures the spatial variability in net solar radiation, but the apparent map does not

Photovoltaic solar water heating system

Abstract: A system for heating water using solar energy comprises a photovoltaic array, a water heater comprising a variable resistive load, and a controller for varying either the load characteristics of the resistive load or the power generating characteristics of the photovoltaic array, or both, to ensure maximum power transfer efficiency.

Passive solar buildings

Abstract: This companion to Passive Cooling and Solar Building Architecture (volumes 8 and 9) describes developments in passive solar technology that will save time, energy, and resources in planning for the buildings of the future. It is filled with tips and useful research for architects and designers and includes three substantial chapters on general modeling."Passive solar heating works. Properly designed and constructed, it is cost-effective, practical, comfortable, and aesthetic." Balcomb's introductory remarks set the tone for the rest of the contributions, which describe the considerable record of achievements in passive solar heating. Balcomb summarizes and evaluates the era between 1976 and 1983 when most of the major developments took place and highlights the design features that have contributed to effective buildings.Three chapters cover modeling passive systems (applicable to both heating and cooling), and six chapters focus on the application of passive solar heating, with emphasis on components, analytical results for specific systems, test modules, subsystem integration into buildings, performance monitoring and results, and design tools.J. Douglas Balcomb is a Principal Engineer with the Solar Energy Research Institute.

Guide to the Sun

Abstract: 1. History of solar observation: from sun worship to the space age 2. Solar interior 3. The solar photosphere 4. The solar chromosphere 5. The solar corona 6. The active Sun 7. The Sun and the solar system 8. The Sun and other stars 9. Solar energy 10. Observing the Sun Epilogue Glossary Appendices: physical and astronomical constants finding the heliographic co-ordinates of a sunspot Bibliography.

Heterojunction solar cell with passivated emitter surface

Abstract: A high-efficiency heterojunction solar cell wherein a thin emitter layer (preferably Ga0.52In0.48P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7 %. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer.

Solar powered light

Abstract: A solar powered light adapted to be mounted under the eaves of a building, a wall or the like for use in security applications. In a preferred embodiment of the present invention, the solar powered light comprises an adjustable configuration having a lamp with an infrared detector or sensor rotatably mounted thereto and a photovoltaic or solar cell array rotatably disposed at a remote end of an extension arm movably attached to the lamp. Such a flexible arrangement allows the photovoltaic array to be positioned to receive direct sunlight. The sensor activates the solar powered light upon sensing infrared to illuminate the surrounding areas when a presence is sensed and turn it off when a presence is no longer sensed. In accordance with a second embodiment, the solar powered light does not include an infrared detector and provides continuous illumination for a given period of time. In accordance with a third embodiment, the solar powered light does not include an infrared detector, but includes a battery having a higher capacity configured to provide illumination for extended periods of time. In accordance with a fourth embodiment, the solar powered light is configured to be used directly with a user's battery. The solar powered light utilizes a compact fluorescent bulb and circuitry for providing longer lamp life, instantaneous illumination and eliminating flickering during start up.

Siding or roofing exterior panels for controlled solar heating

Abstract: There is disclosed a building structure partially covered with siding panels, the outer surface of which are transparent to solar energy, the panels being slightly spaced from an insulating wall of the building to allow a fluid flow, preferably air, therebetween with effective heat exchange from a solar radiation absorbing surface with the fluid being selectively utilizable for space heating purposes or other purposes. The air can be moved by fans or convection or both. A preferred embodiment employs small horizontal lenticular lenses in the transparent material on the surface of the siding together with a mask, which may be three dimensional, on the back of the siding with the result that when the siding is viewed from the horizontal it displays a decorative color while it is highly reflective for solar rays at high angles of elevation and is transparent for solar rays at low angles of elevation, as during winter months. A black absorbent metallic foil surface may be provided on the insulating wall for absorbing the unmasked solar radiation, and the siding is structured to direct airflow to enhance heat transfer from the radiation absorbing surface. Alternative embodiments utilize spherical lens arrangements and provide panels adapted for roof use with horizontal or low angle orientation. The panels disclosed provide efficient solar heating during the winter with virtually no heat load in the summer, and can have a conventional appearance of any desired color to passersby.

Experimental investigation of an atmospheric-open cyclone solar reactor for solid-gas thermochemical reactions

Abstract: This paper reports that a solar receiver-reactor has been designed to conduct solid-gas chemical reactions, using concentrated solar radiation as the energy source of high-temperature process heat. It consists of a conical cyclone gas-particle separator that has been modified to let concentrated solar energy enter the cavity through a windowless (atmospheric-open) aperture. It combines the advantages of cavity receivers and volumetric reactors, and permits continuous mode of operation. A small-scale prototype reactor to conduct the thermal decomposition of calcium carbonate at 1300 K was experimentally investigated in a solar furnace. Its thermal performance was evaluated. The mean energy absorption efficiency, based on the optically measured power incident on the receiver aperture, was 43 percent. Reaction products showed high degree of calcination.

Self-contained hand-held solar chest

Abstract: A portable, hand-held, completely self-contained, solar energy device that uses only sunlight and solar energy to power a thermoelectric or mechanical chemical cooling and heating system for the use, storage or transportation, of substances requiring temperature tempering or a temperature controlled environment in low, high and medium temperature ranges in an insulated storage chest with an accessible storage cooling or heating chamber of usable practical volume, of at least one cubic foot, with a permanently attached adjustable solar energy collector array of 3.5 square feet for the medium temperature range and 7 square feet for the low and high temperature ranges, that can be carried and operated by the average adult, child and laymen between 60 degrees global north and south latitudes, annually.

Solar energy system

Abstract: The present invention provides a photovoltaic module for converting solar energy into electrical energy The module comprises a substrate having a relatively large first surface and a relatively small second surface A first photovoltaic cell is mounted to the first surface, the first photovoltaic cell having a first response band The module is positioned such that the solar energy is incident onto the active area of the first photovoltaic cell A second photovoltaic cell substantially smaller than the first photovoltaic cell is mounted to the second surface of the substrate The substrate is formed such that a portion of the solar energy transmitted by the first photovoltaic cell into the substrate is directed onto the active area of the second photovoltaic cell Because of the smaller area of the second photovoltaic cell, the cost per unit cell area is lower than in conventional tandem cell designs

43rd Congress of the International Astronautical Federation

Abstract: Missions to Mars will require electric power. A leading candidate for providing power is solar power produced by photovoltaic arrays. To design such a power system, detailed information on solar-radiation availability on the Martian surface is necessary. The variation of the solar radiation on the Martian surface is governed by three factors: (1) variation in Mars-Sun distance; (2) variation in solar zenith angle due to Martian season and time of day; and (3) dust in the Martian atmosphere. A major concern is the dust storms, which occur on both local and global scales. However, there is still appreciable diffuse sunlight available even at high opacity, so that solar array operation is still possible. Typical results for tracking solar collectors are also shown and compared to the fixed collectors. During the Northern Hemisphere spring and summer the isolation is relatively high, 2-5 kW-hr/sq m-day, due to the low optical depth of the Martian atmosphere. These seasons, totalling a full terrestrial year, are the likely ones during which manned mission will be carried out.

Optimization of a solar‐driven heat engine

Abstract: The optimum performance of the solar‐driven heat engine consisting of a solar collector and a heat engine is investigated, based on the linear heat‐loss model of solar collectors and the endoreversible Carnot cycle model of heat engines. Some new results such as the optimum operating temperature of the solar collector, the maximum overall efficiency of the system, the optimum operating temperatures of the working fluid in two isothermal heat exchange processes of the heat engine, and so on, are derived. It is expounded that these results have more realistic meaning than the previous relative theoretics for the optimum design of practical solar‐driven heat engine systems.

Sunshape and its influence on the flux distribution in imaging solar concentrators

Abstract: In this paper we present measurements of the sunshape and investigate its influence on the flux distribution in the solar furnace at Paul Scherrer Institute (PSI) and in parabolic concentrators, both experimentally and by a ray tracing procedure. The influence of the spectral dependence of the sunshape is analyzed. Various sunshapes are compared with the corresponding flux distributions in the two-wtage solar furnace at PSI