Inflated Cylindrical Solar Concentrator for Producing Industrial Process Heat

摘要

The use of industrial process heat below 170 exp 0 C accounts for 5% of this country's total energy consumption. A concentrating solar collector to produce hot water and steam in this temperature range is under development. The collector structure consists mainly of an inflated thin-film plastic cylinder that is clear on the upper portion and is an aluminized reflector on the lower portion. The reflector concentrates sunlight on a receiver tube which is jacketed with a heat transfer suppressing, thin-film plastic cylinder. Because of its simplicity, it is believed this collector will be cost-effective relative to fossil fuels such as oil at $15/bbl. Computer codes have been written to analyze the optical and thermal properties of this collector. Results indicate that weekly tilting of the collector provides over 90% of the energy available from continuous tracking. A selective surface on the receiver tube ( alpha = 0.92, epsilon = 0.20) increases the useful energy gain by more than a factor of five at 170 exp 0 C. The stagnation temperature at the outer receiver tube surface is calculated to be below 350 exp 0 C. Combining calculated optical and thermal efficiencies gives an overall collector efficiency of 20% for 170 exp 0 C operation. This figure is based on an aperture of the full diameter times the length, and on beam radiation. The first experimental collectors are being constructed to verify our computer code studies. These units are 4m long with an outer diameter of 1m. (ERA citation 03:023452)