solar enery 2007

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By: Carlos31 (42 month(s) ago)

bem legal.muita informaçao util!parabens pelo site

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WHY CHOOSE RENEWABLES?

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Ultimate energy source Nuclear fission Nuclear fusion solar energy (fusion)

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Solar Technologies Photovoltaics (PV) Photovoltaic solar cells, which directly convert sunlight into electricity, are made of semiconducting materials. The simplest cells power watches and calculators and the like, while more complex systems can light houses and provide power to the electric grid. Passive Solar Heating, Cooling and Daylighting Buildings designed for passive solar and daylighting incorporate design features such as large south-facing windows and building materials that absorb and slowly release the sun's heat. No mechanical means are employed in passive solar heating. Incorporating passive solar designs can reduce heating bills as much as 50 percent. Passive solar designs can also include natural ventilation for cooling. Concentrating Solar Power Concentrating solar power technologies use reflective materials such as mirrors to concentrate the sun's energy. This concentrated heat energy is then converted into electricity. Solar Hot Water and Space Heating and Cooling Solar hot water heaters use the sun to heat either water or a heat-transfer fluid in collectors. A typical system will reduce the need for conventional water heating by about two-thirds. High-temperature solar water heaters can provide energy-efficient hot water and hot water heat for large commercial and industrial facilities.

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A small solar furnace with A dish that is 6.7056 meters in diameter A heliostat that is 95 m?/font> This furnace provides 16 kW total thermal power Peak flux up to 500 W/cm?

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Solar Heat Pump

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General Description (from the contract): NASA JSC is investigating Solar Heat Pumps as a technology which will improve thermal control for future human space missions in hot environments such as the moon. Since this technology is very attractive for use on earth JSC's solar heat pump work has been structured as a dual-use development project. Vehicle solar air-conditioners and solar refrigerators are two commercial products which are potential outgrowths of developing this technology. JSC has completed a conceptual design for a solar photovoltaic (PV) powered heat pump which provides 50 kilowatts of cooling for a lunar base habitat (reference 1). Cooling is required from sun-up to sun-down with the greatest temperature lift required at noon when the thermal environment is the hottest. Studies have shown that a minimum mass system can be achieved by connecting a lightweight horizontal PV array directly to a variable speed compressor in a vapor compression heat pump. Heat pump power demand tracks PV power availability nicely, thus heavy and expensive power storage devices are eliminated. On earth, this type of variable speed direct-drive "solar compressor" would provide cooling in proportion to the amount of sunshine available and rely on thermal rather than electrical energy storage. In order to demonstrate a solar heat pump such as the lunar base system described above (but on a small scale) and at the same time promote commercialization of the technology, JSC would like to procure a variable speed direct-drive solar PV heat pump compressor with motor and controller (hereafter called "solar compressor" The solar compressor will be installed in a solar refrigerator. A well insulated refrigerator cabinet of approximately 300 to 500 liters will be used and a cooling capacity of approximately 40 to 150 Watts is desired of the solar compressor. The refrigerator cabinet will incorporate a water/ice system to store thermal energy so that extra cooling can be done during the day to carry the system through the night. A nominal 12 or 24 volt PV panel with a maximum output of 120 Watts will be used as the only power source. The main challenges will be to overcome the typically high startup current of the compressor/motor without using a battery and to utilize the solar energy as fully as possible. An existing commercial PV panel will be used for testing at JSC (see Interfaces below) . The subject of this procurement is the variable speed direct-drive compressor with motor and controller (i.e. solar compressor) . The compressor must work with refrigerant 134a. A temperature feedback signal from the refrigerator will also be available for the controller to use.

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Polar delivered a compressor which operates from a solar photovoltaic array or battery source of 12 to 32 Vdc. Input power ranges from 120 to 280 watts. Cooling range is from –50 F to 85 F. Terrestrial applications include: Solar powered refrigerators in the 5 to 40 cubic foot range, freezers in the 3 to 20 cubic foot range, and dehumidifiers, ice makers, and beverage vending machines. Military applications include field portable freezers, refrigerators, ice makers, special freezing applications, and environmental control. Other commercial applications include: food and beverage dispensers for aircraft, bus, and train. Larger capacity compressors can be manufactured by Polar using the technology for solar air conditioning and larger freezers and refrigerators, etc.

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Solar geometry : Relationship of the sun’s rays with a surface on earth Solar intensity Glass response to solar energy