Showing papers on "Photovoltaic thermal hybrid solar collector published in 1988"

Method of and apparatus for producing power from solar energy

Abstract: The present invention provides a method of and apparatus for producing power from solar energy wherein a solar collector heats gas supplied to a gas turbine; compressors compress the gas, the gas being compressed and stored gas during a first period of time, with the stored compressed gas being supplied to the gas turbine during a second period of time to produce power by driving an electric generator Preferably, the first period of time is during periods of off-peak electricity, which normally occur at night The second period of time is during the day The solar collector preferably comprises tracking reflectors for focusing solar radiation and a receiver for receiving the focused solar radiation and also heating the gas The solar radiation receiver preferably comprises a rotating ceramic member Furthermore, a combustion chamber is preferably provided to heat the gas entering the gas turbine and is operated by a temperature sensing/control unit when the solar radiation received by the receiver is insufficient to heat the gas entering the gas turbine to the required temperature The electric motor used to operate the compressors preferably comprises the electric generator of the gas turbine Furthermore, heat generated during the compression of the gas and contained therein is transferred to another fluid in a heat exchanger which comprises part of waste heat converter for producing electrical power therefrom

A Fundamental Equation for Exergy Balance on Solar Collectors

Abstract: This paper presents the energy balance equation on a solar collector which acts as the fundamental and principal expression for the solar thermal design. The equation fully explains the exergy loss processes and can be used to derive the approximate optimum operating condition for solar collectors. Furthermore, using the equation, it can be shown that two different collectors, an evacuated tubular collector and a flat-plate collector, have both nearly equal capabilities in exergy gain despite large differences in technological efforts and expenses to produce them. In addition, ways for improvement for a solar collector are also discussed here briefly.

Solar powered construction light

Abstract: A recharging network for a solar powered construction light, including a solar powered battery, that recharges a storage battery at a constant rate and can be selectively operated to burn the light continuously to produce a continuous light or to burn intermittently to provide a flashing light. The network allows a solar cell to recharge the storage battery when sunlight is impinging upon the solar cell to provide virtually maintenance free and long term operation of the construction light during the dark or twilight hours when construction lights are commonly employed to warn motorists of road hazards.

Solar Design: Components, Systems, Economics

Abstract: This book's contents are: Solar Radiation Calculations; Solar Collectors; Thermal Energy Storage; Solar Energy Economies; Solar Domestic Water Heating; Passive Space Heating; Active Space Heating; Solar Cooling; Natural Lighting; Special Topics: Solar Ponds, and Photovoltaics.

Output power and efficiency upper bound of real solar heat engines

Abstract: SYNOPSIS Maximum power and efficiency at the maximum power of an irreversible solar heat engine are treated. When time is explicitly considered in the energy exchanges between the solar heat engine and its surroundings, it is found that there is a bound on the efficiency of the real solar heat engine at the maximum power condition. This bound can guide the evaluation of existing solar power generating systems or influence design of future solar heat engines.

Solar PV-thermoelectric generator hybrid system: case studies

Abstract: A solar photovoltaic (PV) thermoelectric generator (TEG) hybrid system combines the economics of a solar photovoltaic system with the reliability and heating capability of a thermoelectric generator system. The solar system provides power during seasons with abundant sunshine while the thermoelectric generator system provides power and heat as required during seasons with insufficient solar insolation or during extended periods of inclement weather. The author discusses the principle of operation of a thermoelectric generator and solar PV-TEG hybrid system, and examines two existing sites in northern Canada. It is concluded that, to obtain maximum reliability and still remain cost-effective, the design of a remote power system must be tailored closely to individual site requirements, location, and ambient temperatures. It has been found that at locations where delivered fuel costs become significant and stand-alone solar is not a viable alternative, a solar PV-TEG hybrid system can provide unmatched reliability and economics. >

Hot-water heater in the form of a solar collector

Abstract: Solar-heated flow-type instantaneous water heater in the form of a solar collector with an integrated storage mass of phase-changing material. The water to be heated (1) flows directly through the absorber (2, 7) thereof and is heated in the main directly by the solar radiation, without the intermediary of a storage medium. The heat not thus dissipated is supplied to the storage mass (3), which is in direct, thermally well-conducting contact with the absorber.

Techno-economic performance analysis of solar cooling systems

Abstract: Vapour absorption cooling systems, powered by solar thermal energy, are now commercially manufactured in sizes ranging from 1.5 to over 20 RT (one refrigeration ton = 3.51 kW of cooling). The needed thermal energy at appropriate temperature potential can either be provided by solar thermal collectors or else from a solar pond. The paper gives the assessment criteria and results for technical and economic evaluation of the performance of absorption chiller using a solar pond. These results, based on Kuwait's environmental data and costs, have been compared with three alternate cooling systems, namely: 1 Solar thermal collector absorption cooling system. 2 Solar photovoltaic cooling system. 3 Standard vapour compression cooling system. The criteria, used for performance evaluation of the solar cooling systems on a technical basis, consists of assessing the extent to which such systems can make a positive contribution in a conserving fossil fuel. This is done by first estimating the total electrical energy needed by the standard system (defined in para. 3 above) to produce one unit of cooling output. Solar cooling systems are then analysed and compared with a standard system to establish their electrical energy saving or generation capability, after accounting for the parasitic electrical energy used in pump/fan motors and equivalent energy needed for the production of soft water (used-up in the cooling tower) from seawater desalination. The economic analysis considers the cost and life of subsystems and that of the electrical and water desalination plants to arrive at the unit cooling cost. The unit cooling is defined as the ratio of amortized capital investments plus operation and maintenance costs over the year and the total yearly cooling production by the system. The results show that the solar pond absorption cooling system is the closest competitor to the conventional cooling system.

太陽熱利用ヒートポンプシステムの研究 : 第1報,異種の直膨形太陽集熱器を並列に用いたヒートポンプ

Abstract: It was shown experimentally that the thermal performance of a heat pump system with a collector (evaporator) which had high convective heat transfer coefficient was not bad even when the solar incident radiation became small. However, with this collector the solar radiation increased the coefficient of performance (COP) little. On the other hand, with a collector which had a low convective heat transfer coefficient, the COP was very high when the solar radiation was available and was very low when it was not available. Thus, each collector had an advantage and disadvantage depending on the weather conditions. It was considered to use these two different types of collectors arranged in a row in the heat pump system. As a result, the weak point of each collector was covered by the other collector resulting in a good performance.

The costs of photovoltaic concentrator modules

Abstract: The results of comparative studies for PV concentrator modules are presented. The US Department of Energy (DOE) goals for photovoltaically generated energy are $0.12/kWh for the near-term (early 1990s) and $0.06/kWh for the year 2000. Based upon module cost projections supplied by six module developers, it is likely that the near-term goal could be met given sufficient production volume. Further cost reductions, which require innovative module designs, are necessary to meet the longer-term goals. >

Solar Energy Applications to Buildings and Solar Radiation Data

Abstract: European Solar Microclimates.- Data on Solar Radiation at Earth from Satellite Measurements (Project SUNSAT).- EUFRAT: Uti1izability and Cumulative Frequency Curves of Solar Irradiance.- OPSYS: Concerted Action for Solar System Model Development and Validation.- The European Solar Storage Testing Group.- CAM.UR: A Computer Aided Management System for Urban Passive Renewal.- PASCAUD: Passive Solar in Computer Aided Urban Design.- Survey of the Existing Building Stock to Assess the Passive Solar Potential.- Passive Building Control.- Interzone Airflow.- Thermal Comfort in Passive Solar Buildings.- Field-Based Research on Thermal Comfort in Passive Solar Buildings.- European Concerted Action Programme on Daylighting.- Project Monitor.- Monitoring of Two Passive Solar Houses.- Technology Transfer from the Solar R&D Community to the European Building Professions: SOLINFO.- Architecture and Solar Energy: ARCHISOL.- The Project PASSYS.- List of Participants.

Technoeconomic optimization of a hybrid solar air‐heating system

Abstract: This paper presents a simple techno-economic model for a hybrid solar air-heating system based on water as the storage medium. The configuration of the system consists of a conventional solar air-heater, water tank for thermal storage, a unit which adjusts the higher air temperature (during peak sunshine hours) to the required limit (by mixing fresh air) and an arrangement for providing auxiliary energy if and when required. A thermostatically controlled electric heater is assumed to be the source of auxiliary energy, in the present calculations. In order to evaluate the performance of the system using the developed model numerical calculations have been made corresponding to the climate of Delhi, India. The calculations have been extended to obtain the optimized values of collector area and storage mass which correspond to the minimum value of useful energy. Numerical results show that the cost of useful energy obtained for optimized values of collector area and storage mass is much less than the cost of electrical heating.

Solar photovoltaic technology: The thin film option

Abstract: Photovoltaics (PV) the direct conversion of sunlight to electricity was first discovered by scientists at the Bell Labs in 1954. In the late 1960's and 1970's most of the solar cell technology has been used for space applications to power satellites. The main work horse for the PV technology has been crystalline silicon (Si) solar cells. Over the past 15 years this has led to cost reduction from $35/kWh to about $0.30/kWh at the present time. Demonstrated reliability of 20 years or more has resulted in acceptance by several utilities. However, cost reductions in crystalline Si solar cells have been limited by the cost of wafering of ingots and the attendant loss of material. A number of Si sheet solar cells are also being investigated. In the past decade the emphasis of the research and development effort has been focused on thin film solar cells, which have the potential for generating power at much lower cost of $1-2/Wp. Thin film solar cells that are presently being investigated and are generating global attention are: amorphous silicon (a-Si:H), cadmium telluride (CdTe), and copper indium diselenide (CuInSe/sub 2,/ or CIS). In the past few years, considerable progress has been; made by all threemore » of these thin film solar cells. This paper reviews the current status and future potential of these exiting thin film solar cell technologies.« less

Heat Exchanger Theory Applied to the Design of Water- and Air-Heating Flat-Plate Solar Collectors

Abstract: A general method for the design of flat-plate solar collectors based on solar collector theory has been developed. It can be applied to both liquid- and air-heating solar collectors. The solar collector efficiency is determined by the product of the effectiveness (/epsilon/) and the isolation use factor (IUF). The effectiveness describes the heat transfer characteristics of the collector and is shown to be a function of a solar number of transfer units (SNTU) and a parameter psi. For an air-heating collector, the psi parameter equals the collector efficiency factor, while for a liquid-heating collector it must account for the difference between the plate and tube heat transfer areas. The effectiveness and SNTU parameters are similar to the effectiveness and NTU parameters used in heat exchanger design methods. The IUF is a measure of the operating conditions of the collector. It represents the difference between the transmittance-absorptance product and the ratio of the minimum heat loss to the isolation of the exterior cover. The relationship between the effectiveness and the SNTU parameter is general for all nonconcentrating collectors. One advantage of this method over the traditional Hottel-Whillier method is that it separates the heat transfer characteristics of the solar collector frommore » its optical properties and the operating conditions.« less

Static concentration systems with enhanced light concentration

Abstract: Static concentrators are investigated in conjunction with high-efficiency solar cells to reduce solar cell area, and thus cost significantly. Two means of light concentration are introduced, one resulting in a gain by a factor of two. Other static concentrator designs are introduced leading to concentration factors of up to ten. The limitations and energy losses of these concepts are analyzed. >

Short focal length concentrating photovoltaic collector

Abstract: The design and prototype production of a short focal length concentrator are presented. The cost benefits, objectives, and system design for the concentrators are discussed in detail. The design results in a production-cost reduction because it allows the concentrator to be produced with full-automation techniques and uses far less nonPV material than is used for standard concentrators. 12% module efficiencies were obtained using a standard one-sun cell at 30:1 concentration. Costs are less than a dollar per watt for the module. >

A hybrid thermal energy storage design

Abstract: The thermal performance of the seasonal heat energy storage system in Kerava solar village is discussed. The hybrid thermal energy storage employed in Kerava comprises a subsurface water storage surrounded by vertical heat exchanger pipes in the rock. The measured yearly heat recovery efficiency of the storage system has been of the order of 80%. To increase the capacity for storage of summertime solar heat, an improved storage operational strategy has been suggested which could increase the yearly solar fraction by 6–9%-units.

Estimation of solar collector area and thermal energy requirement in absorber heat recovery cycle

Abstract: The present communication includes a thermodynamic evaluation of the solar collector area required and thermal energy needed for a fully solar-dependent vapour absorption system. A comparative study of the absorber heat recovery cycle and the basic absorption cycle has been made in terms of percentage decrease in solar collector area, amount of heat rejection and thermal energy required in Watt thermal equivalent per 1 kW of cooling. Three refrigerant absorbent combinations, namely H2OLiBr, NH3H2O and NH3LiNO3 are used for detailed analysis of the absorber heat recovery cycle for solar cooling purposes.

Cost-effectiveness of solar thermal and electrical energy production

Abstract: SYNOPSIS Solar electricity and also solar thermal energy at moderate temperatures, typically 80 to 90°C, can be used for operating systems to provide cooling and water desalination. We analyze the techno-economic viability of converting solar energy to thermal or electrical form. The analysis shows that, when compared with the conventional process of electricity production, the conversion of solar energy to electrical form is highly uneconomical. On the other hand, conversion of solar energy to thermal form can compete with oil based thermal energy production.

Prismatic solar thermal collector

Abstract: A prototype solar thermal collector, named “Prismatic Solar Thermal Collector” was designed, fabricated and tested The collector of this type employs the phenomenon of total internal reflection The collector tests show a high optical efficiency of 087 and of 078 with an additional glass cover The heat loss coefficient of the collector decreased from 22 W/m2 C to 13 W/m2 C by fixing the additional glass cover The flow pattern of the working fluid in the collector was not too critical for the performance as solar radiation was mostly absorbed directly by the working fluid As the collector had a high storage capacity, it was also tested as a collector-cum storage solar water heater The additional glass cover increased the water heater efficiency as expected The mean fluid temperatures of the collector predicted from a modeling equation were very close to the experimental values

Solar systems beyond our own

Abstract: The belief that our Solar System is only one of many seems to be confirmed in new measurements of the oscillatory motions of distant stars.