| 摘要 |
In a shell and tube heat exchanger, the tubes are arranged as several concentric rings of tubes. Each concentric ring of tubes is twisted through an angle to form a helix. The angle through which the tubes are turned is different for each ring of tubes so overall length of each tube remains constant. The direction of rotation of the rings of tubes may be opposed in different rings of tubes. In addn., the tubes are corrugated which increases turbulencee and hence heat transfer in shell and the tubes. The method of mfg. the heat exchanger is simplified by turning the ring of tubes through an angle to give a required length of tube. The fig. shows a heat exchanger with only one tube of an inner ring (1) and an outer ring (2) of tubes wound helically, in opposite directions, round a blind tube (8) within an outer shell (3). The end of each tube is widened at its end so each tube is close to its neighbours. The joints between the tube ends are welded or soldered to form an end plate (4) which connects it inlet and outlet connections (5). Each tube is corrugated along its length by slightly flattening the tube in alternating directions - pref. 90 deg. The shell medium flows through inlet and outlet connection (6). During mfr., a ring of tubes is turned until the required tube length is obtd.; i.e. angle of progression of the helix does not have to be calculated prior to mfr. (10pp Dwg.No.1/5) |
