Evaporative-cooling apparatus and method for the control of web or

Abstract

Disclosed is an apparatus for providing a shower of fog onto a web or a machine component in contact with a web. The fog, which has a temperature lower than the temperature of the surface of the web or the machine component to be cooled, is applied to the surface and is caused to evaporate by the difference in the temperatures. A supply of dry air is supplied to transport the evaporated fog from the region surrounding the surface to be cooled. Fog may be generated through the use of an air-atomizing nozzle which propels water and compressed air through a small orifice under pressure to create an atomized mist or fog. The fog may also be generated through the use of an ultrasonic transducer which expels fine droplets of water from its surface by means of a high-frequency oscillating transducer motion. In one embodiment, the fog may also be generated in controlled specified quantities locally at each nozzle as required to provide for a controllable fog application rate across the full apparatus width. Alternatively, the fog may be generated at a single source and then supplied to a common cross-machine plenum with the flow of fog to each nozzle location being regulated by a suitble flow control valve positioned at each nozzle location.