Abstract:
To knife-coat elastic liquids without the presence of flow instability, the extension rate in the upstream region of the coating bead is kept low by increasing the distance over which the liquid must accelerate. The onset of the flow instability is delayed by insuring that the upstream liquid-air interface of the coating bead is relatively long and flat. This is accomplished by allowing the elastic liquid to pull itself over a relatively large distance out of a trough and into the knifing passage. The liquid is able to ascend into the knifing passage by virtue of liquid tension developed by the extensional flow in the upstream region of the coating bead.
Abstract:
The invention is a catalytic air cleaner made from a double spiral formed by winding together two strips of metal. The strips are coated with a combustion catalyst. One spiral passage leads into the core of the spiral and the other passage leads out of the core. An electric resistance heater supplies heat at the core of the spiral. The outflowing air transfers this heat to the inflowing air, through the walls of the spiral. Because of this heat exchange, the difference between the temperature of the air at the core and the air entering the spiral can be many times the difference between the temperature of the air entering and leaving the spiral. Contaminants in the air are burned on the catalytic surface with a minimum input of heat. The invention also includes a method of designing a spiral having optimum characteristics.
Abstract:
A cross flow knife coater includes a coating station through which a surface passes and a trough which extends transversely across the desired width of the coating. The trough has an opening through which coating fluid exits onto the surface without using a slot, and first and second transverse ends. The coating fluid is fed directly into the trough at a first transverse end, and is moved from the first transverse end of the trough, across the trough, and toward the second transverse end to cause the coating fluid to flow across the width of the trough while coating fluid exits the opening. The coater creates a spiral flow of coating fluid across the width of the trough which carries debris, bubbles, and other undesirables across the trough to a second traverse end where they can be vented. The perpendicular distance between the trough opening and the surface, and likewise between the knife and the surface, can be adjusted.
Abstract:
A coating insert used within a coating assembly for defining at least one edge of coating fluid as it is applied to a substrate moving past the coating assembly is disclosed. The coating assembly includes a trough having first and second transverse ends. At least one coating insert is inserted within the trough to define an edge of coated fluid on a substrate. The coating insert, having one or two edge-defining surfaces, is positioned within the trough. The first end of the edge-defining surface is closer to the adjacent transverse end of the trough than the second end of the edge-defining surface. The top face of the coating insert may also include a second edge-defining surface having first and second ends that may define another edge of coated fluid on a substrate.
Abstract:
A cross flow knife coater includes a coating station through which a surface passes and a trough which extends transversely across the desired width of the coating. The trough has an opening through which coating fluid exits onto the surface without using a slot, and first and second transverse ends. The coating fluid is fed directly into the trough at a first transverse end, and is moved from the first transverse end of the trough, across the trough, and toward the second transverse end to cause the coating fluid to flow across the width of the trough while coating fluid exits the opening. The coater creates a spiral flow of coating fluid across the width of the trough which carries debris, bubbles, and other undesirables across the trough to a second traverse end where they can be vented. The perpendicular distance between the trough opening and the surface, and likewise between the knife and the surface, can be adjusted.