GB826681A - Improvements in heat exchangers - Google Patents

Abstract

826,681. Heat exchangers. WAAGNERBIRO A. G. July 2, 1956, No. 20488/56. Class 64(3) [Also in Group II] In a combined heat exchanger and centrifugal separator in which a gas is heated or a liquid evaporated by means of a heating gas, the heating gas is caused to move with a helical flow in a direction generally parallel to the other fluid and, to improve the rate of heat transfer, the boundary layers of gas together with dust &c. particles contained in the gas are withdrawn a plurality of times during each rotational movement of the gas and are thereafter returned to the main gas stream. In the form shown the fluid passages are formed by a group of juxtaposed tubular elements 1 of star-shaped crosssecton, the fluid to be heated flowing through passages within the elements and the heating gas flowing through other passages 2 each defined by ribs 1<SP>1</SP> of adjacent elements 1. The ribs 1<SP>1</SP> are grooved as shown at 6 and pair of adjacent ribs co-operate to form a slit in the wall of a passage 2, a plurality of such slits being provided through which the boundary layers of the whirling stream of gas are withdrawn as indicated by arrows 5, the gas withdrawn being subsequently returned to the main stream downstream of the passage 2. The whirling motion of the gas may be effected by separate guides or helical vanes 4 (Fig. 1) or by vanes formed integrally with the elements 1 (Fig. 11, not shown). Alternatively (Fig. 3) helical vanes in the heating gas passage may be carried on a tube 14 extending therethrough in which the same or a different fluid to be heated or evaporated flows. The fluid to be heated or evaporated may also be given a whirling motion and its boundary layers withdrawn to improve heat transfer, and in addition, displacer elements (Figs. 8, 9, not shown), may be fitted to vary the cross-sectional area of the passage. The elements 1 may comprise short ribbed sleeves mounted on a tubular core (Fig. 7, not shown).