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Atmospheric depth and effective solid angle for radiation penetrating the atmosphere
ground solar thermionic conversion system follows. In conclusion, thermionic engines coupled with solar concentrators, promise inexpensive, lightweight, nmintenance-free generators of power in the range of 100 watts to 100 kilowatts having an overall efficiency of about 17 percent for an operation life of up to 50,000 hrs.
XI--Radiation Mechanics and Availability : Insolation, Spectroscopy and Spectral Distribution Ramdas, L. A., National Physical Laboratory, New Delhi, India, "Solar Radiation and Its Measurement at a Net, Work of Stations, with Special Reference to India", United Nations Conference on New Sources of Energy, Rome, 1961, 18 p., Illus. The various types of instruments t h a t have been devised for recording solar radiation are discussed. A. Direct solar radiation by: 1. Angstrom's pyrheliometer 2. Silver disc pyrheliometer 3. Thermopile connected to a milli-voltmeter or galvanometer B. | ) i r e e t solar radiation plus the diffuse radiation from the sunlit sky incident on a horizontal surface: 1. Moll-Gorczynski solarimeter 2. Eppley pyrheliometer 3. Bellani distillation p y r a n o m e t e r 4. Bimetallic actinograph of Rabitzsch type 5. I n t e g r a t i n g solarigraph The intensity of radiation from the sun and sunlit sky has been computed for Indian stations from known relationships between this factor and the controlling factors in the atmosphere, as obtained from data recorded in the United States. The "mtual observations recorded at four stations during the I. (I. Y. are in reasonable agreement with our computed normal values. In the last section of the paper the dependence of the sensitiveness and tinm of response of an Eppley thermopile, on the pressure of the surrounding gas, has been examined at some length and it is shown t h a t though the time of response is greater in vacuum, the sensitiveness is also greatly increased. These times of response are sufficiently small, less than a minute, to ensure accuracy of recording when the equipment is exposed to solar radi'ttion. F u r t h e r studies on this problem are in progress.
Golding, E. W., "Power from Local Energy Resources", United Nations Conference on New Sources of Energy, Rome, 1961, 14 p. To aid development, and to improve living conditions, in many remote, thinly-populated areas a supply of energy is a very i m p o r t a n t requirement. I m p o r t a t i o n of this energy, either through electrical transmission or in the form of fuel, is often prohibitively expensive. An alternative, which may be more economical, is the exploitation of local energy resources such as wind energy, solar energy, or organic wastes. These resources have individual characteristics which need special consideration in relation to the possible power loads and the loads should be planned to match the unconventional methods of power production. The use of local energy resources in combination may offer the best, prospect of success in providing a valuable service to remote communities and experimental schemes should be established to test the possibilities under practical conditions.
Ely, John T. A., "Atmospheric Depth and Effective Solid Angle for Radiation Penetrating the Atmosphere", Ionospheric Physics Laboratory, Geophysics Research Directorate, Air Force Cambridge Research Laboratories, Office of Aerospace Research, USAF, Bedford, Mass., February 1962, 83 p. Illus. This paper presents derivations and numerical evaluation of theoretical expressions for two parameters of interest in prob-
Vol. 7, No. 2, 1963
]ems involving a t t e n u a t i o n of extra-terrestrial radiation by the atmosphere. These quantities are called "atmospheric d e p t h " , or "air mass", and "effective solid angle". The calculations were performed on an IBM 709 computer. "Atmospheric d e p t h " , expressed as mass per unit area traversed along straight paths fronl outside the atmosphere to the location of a detector within the atmosphere, is of importance in the study of cosmic rays, scattering of lights, etc. Atmospheric d e p t h is the line integral of density "~long the ray path. The "effective solid angle" at a given altitude for a given type of flux is defined in this paper as t h a t numl)er which, nmltiplied by the initial value of the isotropic flux outside of the atmosphere, gives the observed omnidirectional flux (flux integrated over solid angle) at the given altitude. The effective solid angles calculated in this paper apply to those cases in which the rigidity of the particles and the geomagnetic latitude of the detector are such t h a t the StSrmer cone fills the whole sky.
Perrot, M. and M. Touchais, "Technical Research Trends at I.E.S.U.A. for Energy Production from Solar Radiation", United Nations Conference on New Sources of Energy, Rome, 1961, 39 p., Illus. In the first part of lhis paper, the authors give several principles t h a t have guided their research. They note, in particular, t h a t , contrary to the general belief, solar energy is a very costly form of energy, which is a b u n d a n t for industrial conversion prinmrily in arid regions, "rod more particularly in the Sahara. There are, however, really no storage problems, except for low-power applications, or when relatively low lemperatures are employed; but ttmre is a problem of auxiliary power, which can be satisfactorily solved with fossil fuels, in the Sahara. The authors note, finally, t h a t the heat sink required for every t h e r m o d y n a m i c t r a n s f o r m a t i o n of solar energy can /)e found in the Sahara only in the atmosphere. This fact is responsihle for the great: interest t h a t attaches to systems capable of moving large masses of air without using any energy other than solar. In the second part of the paper, the authors rapidly examine the systems of collecting and concentrating solar energy now under study, which consist, for temperatures under 300 degrees C, of orientable collectors formed of paraboh)idal mirror elelnents, and operate by multiple focusing. These collectors are designed to heat liquid h e a t - t r a n s f e r agents. For temper'ttures over 300 degrees C, the projects boil down to the utilization of two new processes employing elements of deforlnahle paraboloidal inirrors d i s t r i b u t e d over large surfaces. In the third part, the authors discuss the technical conditions for the development of thermoelectric generators to operate in the Sahara. Two conditions are fundamental: a) Thermoelectric generators must be designed to be cooled by air circulation. But this air may under certain circumstances reach the relatively high temperatures of 40 or 50 degrees C, b) Dirt on the collector systems or t r a n s p a r e n t covers of solar collectors may cause large decreases in tim incident energy and involve high operating expense for cleaning. Surfaces treated to impart selectivity lose their properties when dusty.
Heywood, Harold, "Simple Instruments for the Assessments of Daily Solar Radiation Intensity", United Nations Conference on New Sources of Energy, Rome, 1961, 7 p. Designs for simple i n s t r u m e n t s are proposed which assess the radiation received daily on a flat surface, primarily with the object of predicting performance of flatplate types of solar water heaters. Instead of a pyrheliometer, a capacity instrument is '~dvocated. The heat gained during a period which may vary from a few minutes to the whole day is measured by the rise in t e m p e r a t u r e of a suitable mass of water on metal. After testing several models, the one finally adopted consists of a s t a n d a r d " t h e r m o s " flask with a capacity of one pint (570 ml). The radiation absorbing surface is a blackened copper dish fitted to the flask by means of a copper tube which conducts the heat to tim water in the flask. Provisions "tre made against heat flow from or to the atmosphere. The cost for producing the instrument is estimated to be about eighteen dollars. The t e m p e r a t u r e rise of the water, measured by means of a specially designed maximum and minimmn t h e r m o m e t e r is a measure of the radiation received during a day. 83
XI--Radiation Mechanics and Availability : Insolation, Spectroscopy and Spectral Distribution Ramdas, L. A., National Physical Laboratory, New Delhi, India, "Solar Radiation and Its Measurement at a Net, Work of Stations, with Special Reference to India", United Nations Conference on New Sources of Energy, Rome, 1961, 18 p., Illus. The various types of instruments t h a t have been devised for recording solar radiation are discussed. A. Direct solar radiation by: 1. Angstrom's pyrheliometer 2. Silver disc pyrheliometer 3. Thermopile connected to a milli-voltmeter or galvanometer B. | ) i r e e t solar radiation plus the diffuse radiation from the sunlit sky incident on a horizontal surface: 1. Moll-Gorczynski solarimeter 2. Eppley pyrheliometer 3. Bellani distillation p y r a n o m e t e r 4. Bimetallic actinograph of Rabitzsch type 5. I n t e g r a t i n g solarigraph The intensity of radiation from the sun and sunlit sky has been computed for Indian stations from known relationships between this factor and the controlling factors in the atmosphere, as obtained from data recorded in the United States. The "mtual observations recorded at four stations during the I. (I. Y. are in reasonable agreement with our computed normal values. In the last section of the paper the dependence of the sensitiveness and tinm of response of an Eppley thermopile, on the pressure of the surrounding gas, has been examined at some length and it is shown t h a t though the time of response is greater in vacuum, the sensitiveness is also greatly increased. These times of response are sufficiently small, less than a minute, to ensure accuracy of recording when the equipment is exposed to solar radi'ttion. F u r t h e r studies on this problem are in progress.
Golding, E. W., "Power from Local Energy Resources", United Nations Conference on New Sources of Energy, Rome, 1961, 14 p. To aid development, and to improve living conditions, in many remote, thinly-populated areas a supply of energy is a very i m p o r t a n t requirement. I m p o r t a t i o n of this energy, either through electrical transmission or in the form of fuel, is often prohibitively expensive. An alternative, which may be more economical, is the exploitation of local energy resources such as wind energy, solar energy, or organic wastes. These resources have individual characteristics which need special consideration in relation to the possible power loads and the loads should be planned to match the unconventional methods of power production. The use of local energy resources in combination may offer the best, prospect of success in providing a valuable service to remote communities and experimental schemes should be established to test the possibilities under practical conditions.
Ely, John T. A., "Atmospheric Depth and Effective Solid Angle for Radiation Penetrating the Atmosphere", Ionospheric Physics Laboratory, Geophysics Research Directorate, Air Force Cambridge Research Laboratories, Office of Aerospace Research, USAF, Bedford, Mass., February 1962, 83 p. Illus. This paper presents derivations and numerical evaluation of theoretical expressions for two parameters of interest in prob-
Vol. 7, No. 2, 1963
]ems involving a t t e n u a t i o n of extra-terrestrial radiation by the atmosphere. These quantities are called "atmospheric d e p t h " , or "air mass", and "effective solid angle". The calculations were performed on an IBM 709 computer. "Atmospheric d e p t h " , expressed as mass per unit area traversed along straight paths fronl outside the atmosphere to the location of a detector within the atmosphere, is of importance in the study of cosmic rays, scattering of lights, etc. Atmospheric d e p t h is the line integral of density "~long the ray path. The "effective solid angle" at a given altitude for a given type of flux is defined in this paper as t h a t numl)er which, nmltiplied by the initial value of the isotropic flux outside of the atmosphere, gives the observed omnidirectional flux (flux integrated over solid angle) at the given altitude. The effective solid angles calculated in this paper apply to those cases in which the rigidity of the particles and the geomagnetic latitude of the detector are such t h a t the StSrmer cone fills the whole sky.
Perrot, M. and M. Touchais, "Technical Research Trends at I.E.S.U.A. for Energy Production from Solar Radiation", United Nations Conference on New Sources of Energy, Rome, 1961, 39 p., Illus. In the first part of lhis paper, the authors give several principles t h a t have guided their research. They note, in particular, t h a t , contrary to the general belief, solar energy is a very costly form of energy, which is a b u n d a n t for industrial conversion prinmrily in arid regions, "rod more particularly in the Sahara. There are, however, really no storage problems, except for low-power applications, or when relatively low lemperatures are employed; but ttmre is a problem of auxiliary power, which can be satisfactorily solved with fossil fuels, in the Sahara. The authors note, finally, t h a t the heat sink required for every t h e r m o d y n a m i c t r a n s f o r m a t i o n of solar energy can /)e found in the Sahara only in the atmosphere. This fact is responsihle for the great: interest t h a t attaches to systems capable of moving large masses of air without using any energy other than solar. In the second part of the paper, the authors rapidly examine the systems of collecting and concentrating solar energy now under study, which consist, for temperatures under 300 degrees C, of orientable collectors formed of paraboh)idal mirror elelnents, and operate by multiple focusing. These collectors are designed to heat liquid h e a t - t r a n s f e r agents. For temper'ttures over 300 degrees C, the projects boil down to the utilization of two new processes employing elements of deforlnahle paraboloidal inirrors d i s t r i b u t e d over large surfaces. In the third part, the authors discuss the technical conditions for the development of thermoelectric generators to operate in the Sahara. Two conditions are fundamental: a) Thermoelectric generators must be designed to be cooled by air circulation. But this air may under certain circumstances reach the relatively high temperatures of 40 or 50 degrees C, b) Dirt on the collector systems or t r a n s p a r e n t covers of solar collectors may cause large decreases in tim incident energy and involve high operating expense for cleaning. Surfaces treated to impart selectivity lose their properties when dusty.
Heywood, Harold, "Simple Instruments for the Assessments of Daily Solar Radiation Intensity", United Nations Conference on New Sources of Energy, Rome, 1961, 7 p. Designs for simple i n s t r u m e n t s are proposed which assess the radiation received daily on a flat surface, primarily with the object of predicting performance of flatplate types of solar water heaters. Instead of a pyrheliometer, a capacity instrument is '~dvocated. The heat gained during a period which may vary from a few minutes to the whole day is measured by the rise in t e m p e r a t u r e of a suitable mass of water on metal. After testing several models, the one finally adopted consists of a s t a n d a r d " t h e r m o s " flask with a capacity of one pint (570 ml). The radiation absorbing surface is a blackened copper dish fitted to the flask by means of a copper tube which conducts the heat to tim water in the flask. Provisions "tre made against heat flow from or to the atmosphere. The cost for producing the instrument is estimated to be about eighteen dollars. The t e m p e r a t u r e rise of the water, measured by means of a specially designed maximum and minimmn t h e r m o m e t e r is a measure of the radiation received during a day. 83