| 摘要 |
In my U.S. Pat. No. 4,054,246, a double-walled structure collects solar heat with air as the heat transfer medium, which heat is stored in subterranean gravel pits. In the present invention, (1) the design of the gravel pits is improved, (2) the efficiency of the solar collectors is improved, whereby needed collection area is reduced, (3) seepage into the pits is minimized, and (4) novel modes of operation using ambient air are disclosed.
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