| 摘要 |
<p>An electric fluid flow heating apparatus for heating of paints, lacquers, varnishes and other coating materials in industrial coating operations to control viscosity of a coating material being applied by a spraying apparatus utilizes a pair of low mass electric resistance heating elements (14) located within the legs of a U-shaped fluid flow passageway defining hollow tube (10) havig an inlet manifold (16) and an outlet manifold (18). A fluid mixer (12), formed as a helical metallic spring member having diametrically opposed, axially extending baffles (32) projecting inwardly from the outer diameter of the helical member surrounds each heating element (14) and causes the flow of liquid to follow a generally helical path directed radially inwardly at the baffles (32), to produce continuous mixing of the liquid. Overtemperature safety switch (26) is attached to the outside of the tube (10). The outlet manifold (18) mounts a temperature probe (25) having a thermistor (34) embedded in a conical housing (36) projecting into the fluid flow path and contacting the heating element (14). A proportional-control, slope compensated, electronic temperature control circuit monitors temperature conditions across the flow path sensed by the temperature probe (25) as well as the ambient workplace temperature sensed by an ambient temperature compensator (R3) and regulates the output of the heating elements (14) to provide precise temperature control under varying static and dynamic liquid flow conditions and changing ambient workplace temperature conditions. The control circuit reduces the watt density of the heating elements (14) under conditions of complete static flow to prevent development of excessive liquid temperature.</p> |
