Heat exchange element, a heat exchanger comprising the elements, and an equipment for the manufacture of the elements

Heat exchanger (15) comprising a pack of adjacent heat exchange elements (1) of flexible plastic film material, each element having the form of an expandable bag with inside and outside heat exchange surfaces to enable heat exchange between a pressurized first fluid flowing inside the elements and a second fluid flowing between the adjacent elements (1, 1′), and on each element comprising an inlet opening (2) operably connected with means for supplying said pressurized first fluid, said inlet opening passing the pressurized first fluid to an inside of the element, an outlet opening (3) adapted for discharging the first fluid after heat exchange, and an array of welds (4, 5, 6) bonding the opposite plastic films to define routes for vertical fluid flow through subsequent heat exchange zones inside the bag, and each heat exchange element (1) there are bonds consisting of an array of spot welds (4) in an uppermost first zone (7) of the element adjacent to the inlet opening (2), the uppermost first zone being free of straight oblique welds, an array of parallel extended sinuous welds (5) in a second zone (8) of the element below said first zone, said extended sinuous welds defining parallel sinuous fluid flow channels (11) through the second zone, and an array of oblique welds (6) in a lowermost third zone (9) of the element below said second zone, said oblique welds defining channels (12) for fluid flow towards the outlet opening (3), the oblique welds and said defined channels (12) being arranged on either side about a center axis of the heat exchanger at dissimilar angles, both sides in parallel with a respective outer surface of the heat exchanger.

Equipment for the manufacture of heat exchange elements (1) comprising:

• a succession of three heatable weld rolls (23-25) positioned along a path of travel for a web (22) of double plastic sheet material for provision of a plurality of bag-like elements,
• said three rolls having protrusions for forming welds of spot, sinuous, and converging configurations, respectively, and
• hydraulic or pneumatic means to selectively bring the weld rolls into contact with the moving web and out of contact with the moving web, and
• a backing roll (26) on an opposite side of the web supporting the weld rolls brought into contact with the web,
• wherein said equipment is operable to produce the heat exchange element (1) comprising flexible plastic film material bonded to form an expandable bag with inside and outside heat exchange surfaces, said element comprising i) an inlet opening (2) for supplying a pressurized heat exchange fluid flow to an inside of the element, ii) an outlet opening (3) adapted for discharging the fluid flow after heat exchange, and iii) an array of welds (4-6) bonding the opposite plastic films to define routes for vertical fluid flow through subsequent heat exchange zones inside the bag, and the array of welds consisting of a) an array of spot welds (4) in an uppermost first zone (7) of the element adjacent to the inlet opening (2), the uppermost first zone being free of straight oblique welds, b) an array of parallel extended sinuous welds (5) in a second zone (8) of the element below said first zone, said extended sinuous welds defining parallel sinuous fluid flow channels (11) through the second zone, and c) an array of oblique welds (6) in a lowermost third zone (9) of the element below said second zone, said oblique welds defining channels (12) for fluid flow towards the outlet opening (3), the oblique welds and said defined channels (12) being arranged on either side about a center axis of the heat exchanger at dissimilar angles, both sides in parallel with a respective outer surface of the heat exchanger.