Passive cooling and drainback heating with unglazed radiators/absorbers-the architectural cool cell (patent applied for)

摘要

Radiators covering the roofs of single-story buildings are capable of cooling those buildings over much of the United States. At night, water flows by natural convection through the radiators from ceiling tanks made of large diameter PVC pipe. During the day the sun-warmed radiators cease circulation. Close thermal coupling of room spaces below to the overhead ceiling tanks provides cooling even when night lows are above 68°F. Wetting the same radiators at night greatly increases cooling for periods of high loads. The radiators can be similar to conventional swimming pool collectors but the size of their waterways needs to be substantially larger for cooling-only applications. These radiators can be either light or dark colored. During winter the water level of the system is lowered so the collector radiators are dry until a pump fills them from below and spills warm water back to the ceiling storage tanks in reverse of summer flow. In colder climates, the collectors employed for winter heating should be tilted south to directly face the winter sun. Rotating fins can alternatively expose selective surfaces for winter and nonselective for summer. Eight-inch, thin-wall PVC pipe, running horizontally at the ceiling on 12" centers holds over 20 lbs., of water per sq. ft., of floor exposing 2 sq. ft. of surface per sq. ft. of floor. During summer cooling, water temperatures fall 5°F or 6°F at night and rise the same each day as heat is dissipated and absorbed. Because the density of air changes with temperature, water tanks in the ceiling are excellent at cooling, despite being only cool instead of cold. In winter the collectors can easily absorb heat 50°F above ambient even without glazing or selective surfaces; this is high enough to contribute a significant fraction of heating across much of the southern half of the United States. For comfort in the heating mode, aluminum shutters beneath the PVC pipe can be adjusted to control the rate of radiators to the space below. Although the effectiveness of this system will vary with the specifics of local climates, in the cooling mode it has been found to eliminate the requirement for any supplementary form of space-cooling during the summer of 2000 in Albuquerque, New Mexico, where the outdoor ambient has often exceeded 95°F.