Showing papers on "Photovoltaic thermal hybrid solar collector published in 1984"

Water-borne azimuth-altitude tracking solar concentrators

Abstract: A water-borne tracking solar energy collecting and converting system employing multiple lens collectors for redirecting sunlight for concentration on photovoltaic cells.

Physics Considerations of Solar Energy Conversion

Abstract: A comparative analysis is presented of the conversion of radiant energy to useful work by thermal and quantum processes. The operation of thermal and quantum converters and the thermodynamic conversion efficiency of each are developed in terms of the mechanism of radiation-matter interaction in thermal and quantum systems. From the analysis the maximum conversion efficiency of a single-collector thermal converter with unconcentrated solar radiation and an ambient (reservoir) temperature of 300 K is 0.540; for the same conditions the maximum conversion efficiency of a single-collector quantum system is 0.309. The analysis is extended to consider the effects on the conversion efficiency of heat reject temperature, cascaded operation, in which the reject heat of the quantum converter is used as the input to a thermal bottoming cycle, and of concentration of the solar radiation. The results obtained represent the thermodynamic limits for radiant energy conversion by thermal and quantum processes, and calculations with solar input serve as a reference against which to judge the performance and capabilities of prospective solar energy conversion systems.

Balanced solar concentrator system

Abstract: This solar concentrator system is configured such that the base pedestal attachment point is located on the beam connecting the curved solar reflector and the heat energy receiver power conversion unit, herein envisioned as a Stirling engine. This attachment point is located near the balance point CG (Center of Gravity) of the power conversion unit-supporting beam-curved reflector subsystem such that the loads on the base pedestal and the attached solar tracking drive systems are minimized.

Photochemical conversion and storage of solar energy

Abstract: Research activity in the area of photochemical conversion and storage of solar energy has grown enormously in recent years and currently involves interdisciplinary efforts from many areas such as photochemistry, electrochemistry, catalysis, solid state chemistry and photobiology. The coverage of this review is restricted to publications which appeared in the year 1983 and is discussed under several areas: H2, O2 production from water in homogeneous dye-based systems using redox catalysts, studies related to characterisation of catalysts and mechanism of their operation, heterogeneous photocatalysis and photodissociation of water using semiconductor dispersions and colloids, photogalvanic and photoelectrolysis-galvanic cells, dye-sensitization phenomena and other related topics. Photoelectrochemical studies with semiconductor electrodes (both for the conversion of visible light to electrical energy in regenerative cells and for direct photogeneration of useful chemicals) is one of the major areas in the photochemical solar energy conversion. The present coverage excludes a discussion of all such studies, except to provide a classified, annotated bibliography in the appendix. Fortunately, monitoring of the progress in the area of photochemical solar energy conversion is facilitated by the appearance of several review articles (Calvin, 1983a,b; Fox, 1983; Gratzel, 1983a; Harriman, 1983; Kutal, 1983; Gurevich and Pleskov, 1983; Zamarev and Parmon, 1983) and monographs (Claesson and Holmstrom, 1982; Gratzel, 1983b). There are numerous studies which can play a very important role in the eventual design of photochemical devices for the solar energy conversion which are again omitted in this coverage. These include studies on the improving of the efficiency of charge separation and the prevention of back reactions in photoredox quenching of molecular excited states-both by synthesis of novel sensitizers with appropriate tuning of ground, excited state properties and by the use of various organised assemblies such as micelles, vesicles, polymers, polyelectrolytes, microemulsions, monoand multilayer assemblies, and other multiphase systems such as cyclodextrins, clays, zeolites, etc. Similarly, mention should be made of various photobiological model systems for energy conversion: studies with isolated chloroplasts, chlorophyll or porphyrinquinone complexes, reaction center preparations, enzymes either as isolated ones or immobilised on various supports for water reduction and oxidation. There appears to be a very low level of activity on studies of photochemical energy storage via valence isomerisation (Childs et al., 1983; Jones et al., 1983: Olmsted et al., 1983; Philippopovlos et al., 1983). Porter has addressed the question of thermodynamic efficiency limits for a photochemical system that converts visible light into chemical potential (Porter, 1983).

Solar air heating system

Abstract: A solar air heating system (10) especially adapted for residences where nighttime heating is important. Solar air heating systems have relatively low efficiency, especially when designed to store energy. The parent invention is an improvement to this type of system. The system comprises a solar heat collector plate (43, 60, or 76), an energy storage medium in a subdivided chamber (34) or a structure (64), and a heat exchange means consisting of fins (33, or 44) or walls (65). The fins or walls extend from the chamber or structure wall into the storage medium to subdivide the chamber or the structure to improve the heat exchange relationships of the storage material with its surroundings. The panel is adapted to be incorporated into existing house air heating systems. Air from an enclosure (14) to be heated is drawn through the collector panel (12) by a fan or by natural convection where it extracts heat from the collector plate (43, 60 or 76) and the energy storage medium. The heated air then flows back to the enclosure. High solar collector efficiency is realized because of the unique design of the panel which thermally ties the temperature of a solar collector plate directly to a large thermal mass of energy storage medium. High system efficiency is also realized since an air blower motor is not required to transfer the energy from the collector to the storage volume. Low summer time stagnation temperatures are realized due to the collector plate/energy storage volume relationship.

Heliotropic solar heat collector system

Abstract: A solar energy collector which includes a sun ray window adjacent an array of flat reflector panels each positioned to direct solar energy to a major collector unit on each side of the unit utilizing a secondary reflector plate. A heliotropic mount is provided for the reflector panels. A multiple blind assembly is optionally positioned in the solar window carrying photovoltaic units to convert solar energy and limit the energy selectively to the major collector unit when maximum storage capacity is reached.

Freeze protection valve and system

Abstract: The present invention is a device for a solar heating system having a solar collector, a storage tank connected to the solar collector, a pump for circulating liquid from the tank to the solar collector, a supply of liquid at a temperature above freezing and a connection from the supply of liquid to the solar collector for replacing any liquid lost from said solar collector. The device comprises a sensor for sensing the temperature of liquid in the solar collector, and a valve for bleeding liquid from the solar collector when the sensed temperature falls below a predetermined minimum whereby cool liquid in the solar collector is automatically replaced by liquid at a temperature above freezing.

Portable collapsible solar survival apparatus

Abstract: This invention relates to a portable, high performance solar powered oven, distiller, heater and light directing survival apparatus which is fabricated of light weight, flexible materials that can be easily collapsed for convenient mobility. The invention is formed by concentrating incident solar radiation by means of a funnel shaped reflector into a transparent container which concentrically surrounds a solar heat exchanger. The reflector, transparent container and heat exchanger are constructed in such a way as to permit the heating of food, water, air or desalination reactants to temperatures in excess of 400° F., yet when collapsed, can all fit within the small portable transparent container.

Solar energy storage cell

Abstract: A method of storing thermal energy within solar energy storage cell comprising two materials of differing adsorption properties enclosed within an airtight container. The material having the higher adsorption for water is saturated with water at 70° F. Upon exposure to solar energy, the temperature increases and the adsorbed water transfers to the material having the lower absorbtion. When the temperature decreases in the absence of solar energy, the water returns to the higher adsorption material giving off a substantial amount of heat in the form of heat of adsorption.

Thermal performance of a solar collector containing a boiling fluid (R-11)

Abstract: The experimental thermal performance of a flat-plate solar collector containing a boiling fluid is given for steady and unsteady thermosiphon operation. The steady-state thermal efficiency is shown to compare favorably with a new generalized formulation for collector efficiency. Collectors containing a boiling fluid have a thermal efficiency that is inherently greater than a nonboiling collector having the same value of the thermal parameter. Further, a boiling collector represents a class of solar collectors whose thermal efficiency approaches the theoretical maximum more closely than any other class of collector. The experimental data presented in this paper are taken on an R-11 charged boiling collector in natural sunlight. Experimental time response data are included.

System for supplying energy to buildings utilising solar energy as the energy source

Abstract: A system for supplying energy to buildings utilising solar energy as the energy source, having the following devices: - a solar cell device (80) on the building, in which the solar energy can be converted into electric energy; - a water-electrolysis device (10), in which hydrogen and oxygen can be generated by means of the electric energy supplied by the solar cell device (80), and - a storage device (11), in which at least the hydrogen produced by the electrolysis of the water can be stored.

High yielding solar modulus for the transformation, on photovoltaic cells, of a substantially monochromatic radiation in electric energy

Abstract: The above mentioned invention regards a solar modulus (1) of common type photovoltaic cells, connected with usual means (3) of concentration on it of solar radiation. And this so as to allow the nearly total exploitation of incident radiation through the recovery and consevation in its internal parts of the reflected radiation and the transformation of solar energy. And also of the heat dissipated in it, in the emission, by thermic effect, of a disc (8) of material which has a high thermic conductibility a high absorption of solar radiation and a high fusion point. This emission by thermic effect, is directed to a panel (10) made of one or more photovoltaic cells through a semitransparent filter (9) of selection of the radiation at the characteristic values of activation of the photovoltaic cells.

Solar electric systems

Abstract: Proposers should check in with the receptionist in the lobby. The conference is intended to clarify the solicitation requirements and provide an opportunity for questions and answers. Additional site data is expected to be available for review at the Mandatory Pre-Proposal Conference and the Mandatory Site Tour is scheduled immediately thereafter for the Portland locations. 8:00 a.m. (PST) on each day. DAS will provide transportation to the locations in Salem. There will be no other site tour opportunities for Proposers and their Team members. Lunch will not be provided either day. an authorized representative of the proposing firm is required in order to be deemed Responsive to this RFP, and proposals from those not attending will not be considered for evaluation.

Performance of passive and hybrid solar heating systems

Abstract: SYNOPSIS This paper presents a summary of available performance data for several types of passive and hybrid solar heating systems using heat pipes or thermosyphons to transfer collected solar energy from the absorber to short or medium-term thermal storage located within the building being heated. This location of the thermal storage compared to storage in direct view of the sun is shown to greatly reduce hear losses from storage and to permit solar collection even under unfavourable sun conditions. The heat pipes or thermosyphons are essential in this application since they act as thermal diodes to transfer the collected heat efficiently from collector to storage only while preventing the unwanted reverse heat flow (loss) from storage to the outdoors. The relative simplicity, generally passive nature, efficiency and low cost of these systems makes them excellent prospects for further development to better suit market requirements.

Comparing solar energy alternatives

Abstract: This paper outlines a computational procedure for comparing the merits of alternative processes to convert solar radiation to heat, electrical power, or chemical energy. The procedure uses the ratio of equipment investment to useful work as an index. Comparisons with conversion counterparts based on conventional fuels are also facilitated by examining this index. The procedure is illustrated by comparisons of (1) photovoltaic converters of differing efficiencies; (2) photovoltaic converters with and without focusing concentrators; (3) photovoltaic conversion plus electrolysis vs photocatalysis for the production of hydrogen; (4) photovoltaic conversion plus plasma arcs vs photocatalysis for nitrogen fixation. Estimates for conventionally-fuelled processes are included for comparison. The reasons why solar-based concepts fare poorly in such comparisons are traced to the low energy density of solar radiation and its low stream time factor resulting from the limited number of daylight hours available and clouds obscuring the sun.

Method and device for the technical use of solar energy

Abstract: The invention relates to a method and a device for the technical use of solar energy. In the method, a primary energy transfer medium flows past a solar energy collector and absorbs energy from it. Subsequently, directly or indirectly, at least a part of the energy of the primary medium is transferred to a secondary medium. In order to manage, at least on the primary side, without auxiliary energies, e.g. by means of pump action, the air of the environment is used as primary medium. In terms of the device, this is achieved in that the air heated in the solar energy collector makes possible by its own convection a streaming after of colder air from a lower region.

Thermal and electrical behavior of multistage photovoltaic concentrators

Abstract: A computer simulation has been developed to evaluate the performance of the multistage refractive-reflective photovoltaic concentrators starting from the incident solar radiation to the electrical energy output. The possibility of operating the convertor in the hybrid mode to use the dissipated heat in the solar cells as thermal energy at various temperature levels has been also investigated. Silicon solar cells have been optimized for operation under medium concentration ratios and a prototype uses a combination of linear Fresnel lenses and a reflecting vee-trough has been constructed and tested. Daily electrical and thermal efficiencies are respectively as high as 11% and 54%. Both quasi static orientation and diurnal tracking of the concentrator have been considered. A comparison of several solar systems provides a first order estimation on the effectiveness of multistage concentrators and hybrid systems for industrial and residential applications in favorable climate areas.