GB1376466A - Method of fabricating spirally wound duct-defining units - Google Patents

Abstract

1376466 Making spiral duct-defining units AGA AB and S KNOOS 21 April 1972 [23 April 1971] 18597/72 Heading B3A [Also in Division F4] A method of fabricating a spirally-wound duct-defining unit comprises simultaneously winding at least one strip (2), Fig. 1 (not shown), and at least one spacer element (3) such that the spacer element radially spaces the turns of the strip, securing the turns of the strip by passing elongate fixing elements, e.g. pins 9, Fig. 2, through respective sets of holes, which are radially aligned in the turns of the strip and the outermost holes are spaced about the circumference of the wound strip, each fixing element preventing movement of the strip turns in a plane perpendicular to the fixing element, and removing at least part of the spacer element from the space between some at least of the adjacent turns of the strip. Wires 4, 5, which comprise the spacer element, are wound together with a strip about a core between shields 6, 7, and holes are drilled through the coiled strip to accommodate the pins 9. When winding is completed, the shields 6, 7 are removed and the wires 3, 4 pulled out of the coil or they may be dissolved or melted out by heating. Two or more strips with their spacer elements may be wound simultaneously and alternate elements removed to form flow passages for heat exchange between two media, A, B, Fig. 7. The medium B is supplied through a pipe 29 on either side of the unit and the pipes are secured by soldering, gluing or by dipping in a metal bath. A plurality of units (16)-(20), Fig. 5 (not shown), may be located in axial relationship for use in refrigerating plant or as a thermal regenerator for a gas engine. A liquid fuel burner, Fig. 11, is fabricated by simultaneously winding two strips together with axially spaced spacer elements, which are removed from between alternate turns to form axially directed ducts 38, through which air is passed, and ducts 40 containing metal netting 41 for pumping the fuel by capillary action. In alternative forms of burners, capillary pumping takes place without the use of wire netting, or all the spacer elements are removed and netting is placed between alternate turns of the unit or the netting is located upstream, in the direction of fuel flow, of the spacers, Figs. 13-15 respectively (not shown).