| 165 / | HD | HEAT EXCHANGE |
| DIG 327 | DD | THERMOSYPHONIC HAVING VERTICAL AIR DRAFT PASSAGE {3} |
| DIG 328 | | .~ Air draft passage confined entirely or in part by fin structure {2} |
| DIG 329 | DD | .~.~> Corrugated fin attached to heat transfer surface |
| DIG 330 | DD | .~.~> Air draft passage is parallel to flow direction of heating or cooling means |