Abstract: A method for the manufacture of panel heat exchangers from thermoplastic polyamides. At least one sheet is coated with a coating that facilitates bonding of the polymer to itself under the influence of heat. Two sheets, at least one of which has been coated, are placed between moulds in a press. At least one of the moulds has grooves corresponding to the pattern of fluid flow passages to provided in the panel heat exchanger. The moulds are heated and an inert gas e.g. nitrogen, is applied and passed through the fluid flow passages, to assist in the formation of the passages and to remove any voltatile material from the coating. The preferred coating is benzyl alcohol, phenol and polyamide. The heat exchangers may be used in a variety of end-uses, especially in automotive end-uses.

Abstract: A panel heat exchanger is disclosed. The heat exchanger comprises a generally planar panel having a pair of relatively thin unitary outer walls formed from a composition of a thermoplastic polymer, expecially a polyamide. The walls, which have a thickness of less than 0.7 mm, are bonded together to form a labryinth of fluid passages between the walls. The passages extend between inlet and outlet means and occupy a substantial proportion of the area of the panel. The heat exchangers are relatively economical to manufacture and may be used in a variety of end uses, depending on the properties of the polymer composition, including in some instances as heat exchangers in automobiles.

Abstract: A process for the manufacture of a heat exchanger from a thermoplastic polymer especially a polyamide, is disclosed. The heat exchanger comprises two generally planar panels formed from a composition of the polymer, bonded together to form a labryinth of fluid passages between the panels that extend between inlet and outlet means. The labyrinth occupies a substantial proportion of the area of the panels. The process comprises coating a first panel with a first coating in a pattern corresponding to the fluid passages of the labyrinth, and coating the second panel with a second coating composition in at least those areas where a bond is to be formed with the first panel. The coating compositions are selected so that under the influence of heat, the second coating composition will bond to the polymer composition but not to the first coating; thus the first coating acts as a resist coating. The coated panels are brought into contact and heated so as to effect bonding, and then the passages are expanded e.g.