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This simulator is unique in that it is capable of producing intensities up to 16.0 solar constants (25 solar constants without spectral filters) and closely simulates the solar spectrum over a 12 inch diameter area. The simulator is described and the capabilities, calibration, operational experiences, data collection, and safety considerations associated with this simulator are discussed.
A 2,300-liter hot water storage tank was studied under conditions simulating a solar heating and cooling system. The initial condition of the tank, ranging from 37 C at the bottom to 94 C at the top, represented a condition midway through the start-up period of the system. During the five-day test period, the water in the tank gradually rose in temperature but in a manner that diminished its temperature stratification. Stratification was found not to be an important factor in the operation of the particular solar system studied.
A method is proposed for determining the performance of flat-plate solar collector using a simulated sun. Collector test variables that will help establish the basis for the indoor test facility at the Lewis Research Center are discussed. The use of the indoor testing should permit a standard test for the convenient and accurate determination of collector performance. Preliminary test results are reported as an example of the type of collector performance data to be expected from the simulation approach.
Relative energy flux densities in the penumbrae of various shadowing objects - data tables
Leaf-kill of blades and pine needles by simulated mars, earth, and venus solar radiation
Discusses facility constructed at Marshall Space Flight Center to evaluate performance of solar energy collectors under simulated outdoor conditions. Facility simulates sunfall properties such as radiation intensity, spectrum, collimation, uniformity, and direction.
Oriel Corporation's simulators have a high pressure xenon lamp whose reflected light is processed by an optical system to produce a uniform solar beam. Because of many different types of applications, the simulators must be adjustable to replicate many different areas of the solar radiation spectrum. Simulators are laboratory tools for such purposes as testing and calibrating solar cells, or other solar energy systems, testing dyes, paints and pigments, pharmaceuticals and cosmetic preparations, plant and animal studies, food and agriculture studies and oceanographic research.
In order to study the relationship between different forms of activity and transient variations of the north-south component, B(sub z), of the Interplanetary Magnetic Field (IMF), at 1 AU, a three dimensional numerical simulation code was employed to study several aspects of this problem. One form of solar activity, the flare, is simulated by using a pressure pulse at different locations near the solar surface and observing the simulated IMF evolution of B(sub theta)(-B(sub z)) at 1 AU. It was found, for a given pressure pulse, that the orientation of the corresponding transient variation of B(sub z) has a strong relationship with the location of the pressure pulse and the initial condition of IMF.
A three-dimensional integration of the MHD equations in spherical coordinates has been developed that attempts to simulate a variety of solar wind conditions. These include the interaction of Alfven wave packets and the development of a turbulent cascade, the role of the heliospheric current sheet, the role of quasi-two-dimensional fluctuations in determining how magnetic field lines meander throughout the heliosphere, and the role of interstellar pickup ions in perturbing the solar wind in the outer heliosphere.
An investigation is conducted of the relative benefits of different teleoperator control modes in simulated space servicing. The simulation replicates part of the Solar Maximum EVA Satellite Repair (SMSR) mission of STS-13, in 1974. The formal experimental design and statistical analysis presented demonstrates that position control is superior for small workspace volume management. Quantitative studies demonstrate significant benefits of shared Cartesian control modes for contact tasks; good performance will require the systematic analysis and synthesis of man-machine systems.
This paper describes how collector performance obtained from test data with a simulator can be modified for real-life conditions. The approach taken is to correct the performance data obtained with the simulator for the variable conditions of ambient temperature, wind, incident angle, flow rate, etc., that are encountered in outdoor conditions. Modification of simulator data is accomplished by combining experiment with theory. The technique is demonstrated by application to a spectrally selective and a nonselective type of collector. This kind of modified simulator collector performance data should be valuable in solar systems analyses and for collector performance ranking based on all-day calculated conditions.
Gallium arsenide solar cells are considered for several high temperature missions in space. Both near-Sun and concentrator missions could involve cell temperatures on the order of 200 C. Performance measurements of cells at elevated temperatures are usually made using simulated sunlight and a matched reference cell. Due to the change in bandgap with increasing temperature at portions of the spectrum where considerable simulated irradiance is present, there are significant differences in measured short circuit current at elevated temperatures among different simulators. To illustrate this, both experimental and theoretical data are presented for gallium arsenide cells.
Short-arc xenon lamp proposes to produce more uniform solar output. With this lamp, both axes of sensors can be tested with same setup. Lamp includes cathode with conical tip and annular anode. Annulus is supported by angled projection to avoid interference with passage of light generated by arc.
Commercial glass optical filter corrects spectrum of xenon flashtubes used to test photovoltaic solar cells. Filter withstands thousands of flashes without perceptible alteration of passband characteristics. With filter, calibration errors reduced to less than 1 percent.
Certain climatic tests which require solar and sky radiation were carried out in the laboratory by using simulated global radiation. The advantages of such a method of measurement and the possibilities and limitations resulting from the simulation of global radiation are described. Experiments concerning the thermal load in rooms were conducted in order to test the procedure. In particular, the heat gain through a window with sunshade is discussed, a venetian blind between the panes of a double-glazed window being used in most cases.
This paper reports the measured thermal efficiency and evaluation of 23 collectors which differ according to absorber material (copper, aluminum, steel), absorber coating (nonselective black paint, selective copper oxide, selective black nickel, selective black chrome), type of glazing material (glass, Tedlar, Lexan, anti-reflection glass), the use of honeycomb material and the use of vacuum to prevent thermal convection losses. The collectors are given performance rankings based on noon-hour solar conditions and all-day solar conditions. The determination with the simulator of an all-day collector performance is made possible by tests at different incident angles. The solar performance rankings are made based on whether the collector is to be used for pool heating, hot water, absorption air conditioning, heating, or for a solar Rankine machine.
A general expression was derived to enable calculation of the calibration error. The information required includes the relative spectral response of the reference cell, the relative spectral response of the cell under test, and the relative spectral irradiance of the simulator (over the spectral range defined by cell response). The spectral irradiance of the solar AMX is assumed to be known.
Simulation of the surface region and interior of the Sun's convection zone. The objective is to provide understanding of the tachocline at the base of the convection zone. of the differential rotation generated by global convective motions, and of supergranules that are observed on the solar surface. Two large-scale simulation codes are used, one for the global dynamics in spherical coordinates and another for the local surface events in Cartesian geometry. We work in close collaboration with the Helioseismic and Magnetic Imager instrument developers for the Solar Dynamics Observatory satellite. NASA Program: Living with a Star - Sun-Earth Connection.