Abstract: In the manufacture of a fin and tube heat exchanger coil, a protective coating is applied to selective portions of the tubing in order to prevent corrosion of the fins due to galvanic corrosion and/or to prevent corrosion of the tubing due to formicary corrosion. The coating is applied to selective portions of the tube to include that portion that comes in direct contact with the plate fins or would be exposed to condensate and excluding that portion which is subsequently brazed to return bends.

Abstract: An article having a first member formed from a first metal and a second member connected with the first member at a contact area. The second member is formed from a second metal having high reduction reaction kinetics and galvanic corrosion driving force relative the first member, wherein the second metal is more noble than the first metal. A material for substantially eliminating the galvanic corrosion problem by reducing the reduction reaction kinetics of the second metal in the presence of an electrolyte is provided between the first and second metals. In a preferred embodiment, the article is a heat exchanger wherein the first member is a fin collar and the second member a tube and the material for reducing is a coating on the tube has low reduction reaction kinetics relative to copper for reducing corrosion activities between the tube and fin collar.

Abstract: A heat exchanger fin collar for a plate-fin heat exchanger having close tolerance dimensions for achieving greater contact area on the tube. The fin collar comprises an elongated fin portion for dissipating heat and a leg connected with the fin portion. The leg has a height and includes a straight contact portion substantially perpendicular to the fin portion, wherein the contact portion has a contact height along which the contact portion contacts the tube. The height is in the range of 0.008 to 0.080 inches. It also includes a first curved end portion having a first radius extending from a first end of the contact portion and a stepped transitional portion connecting the contact portion and the elongated fin portion. The transitional portion has a second curved end portion having a second radius, wherein the second curved end portion extends from the contact portion opposite the first end. A method for forming the fin collar and a heat exchanger are also disclosed.

Abstract: A heat exchanger fin collar for a plate-fin heat exchanger having close tolerance dimensions for achieving greater contact area on the tube. The fin collar comprises an elongated fin portion for dissipating heat and a leg connected with the fin portion. The leg has a height and includes a straight contact portion substantially perpendicular to the fin portion, wherein the contact portion has a contact height along which the contact portion contacts the tube. The height is in the range of 0.008 to 0.080 inches. It also includes a first curved end portion having a first radius extending from a first end of the contact portion and a stepped transitional portion connecting the contact portion and the elongated fin portion. The transitional portion has a second curved end portion having a second radius, wherein the second curved end portion extends from the contact portion opposite the first end. A method for forming the fin collar and a heat exchanger are also disclosed.

Abstract: An article having a first member formed from a first metal and a second member connected with the first member at a contact area. The second member is formed from a second metal having high reduction reaction kinetics and galvanic corrosion driving force relative the first member, wherein the second metal is more noble than the first metal. A material for substantially eliminating the galvanic corrosion problem by reducing the reduction reaction kinetics of the second metal in the presence of an electrolyte is provided between the first and second metals. In a preferred embodiment, the article is a heat exchanger wherein the first member is a fin collar and the second member a tube and the material for reducing is a coating on the tube has low reduction reaction kinetics relative to copper for reducing corrosion activities between the tube and fin collar.

Abstract: A method for forming an heat exchanger fin collar for a plate-fin heat exchanger having close tolerance dimensions for achieving greater contact area on the tube. The fin collar includes an elongated fin portion for dissipating heat and a leg connected with the fin portion. The leg has a height and includes a straight contact portion substantially perpendicular to the fin portion, wherein the contact portion has a contact height along which the contact portion contacts the tube. The height is in the range of 0.008 to 0.080 inches. It also includes a first curved end portion having a first radius extending from a first end of the contact portion and a stepped transitional portion connecting the contact portion and the elongated fin portion. The transitional portion has a second curved end portion having a second radius, wherein the second curved end portion extends from the contact portion opposite the first end.

Abstract: A method for treating heat exchanger tubing to be expanded by fluidic or electromagnetic expansion. The tubing treatment reduces the increased material hardness of the tubing in areas where cold work has been imparted thereon. By reducing these areas which have increased material hardness, the tubing will have a substantially similar tube yield along its entire length and can therefore be expanded to substantially the same cross-sectional area throughout by either fluidic or electromagnetic expansion. After forming the cold work regions, the regions are annealed with a heat source, such as through flame or induction heating, and are gradually cooled to avoid the effects of quenching.

Abstract: A method of manufacturing a heat exchanger using fluidic expansion, the heat exchanger having tubing sections interconnected to form at least one circuit for transporting a first heat transfer fluid and conductive fins secured to the circuit for increasing the surface area thereof and increasing the heat transfer between the first fluid and a second fluid flowing among the fins. The tubing sections are positioned in a predetermined manner and the fins are disposed therewith and along the length thereof. The inlets and outlets of the tubing sections are then interconnected to form said the fluid circuit. Next, the fins are secured in place so as not become damaged during the sealing of the interconnections, which follows immediately thereafter. Finally, the entire circuit is expanded to enmesh said fins by enclosing the volume of the circuit and introducing an expansion fluid therein at a pressure which surpasses the tube yield strength of the tubing and causes the walls thereof to expand radially outward.

Abstract: An apparatus for expanding the tubes in a heat exchanger of the plate fin and tube type. The expander is of the type that expands the tubes by driving a "bullet" through the tube with the bullet being attached to and driven by an expander or bullet rod. The apparatus has a sensor positioned so as to be able to measure the compressive force on the expander rod. The output of the sensor is proportional to the force exerted on the rod and can be used to provide an alarm or safety shutdown of the apparatus upon the sensing of excessive force on the expander rod. The sensor output can also be used for quality and process control.

Abstract: A filter system for protecting a heat exchange coil from corrosive constituents carried by an air stream which is passed through the heat exchange coil includes a flexible filter for removing the corrosive constituents from the air stream prior to its engaging with the coil. A net like spacer is located between the coil and the flexible filter for supporting the flexible filter in a predetermined spaced relationship with the heat exchange coil.

Abstract: A single-station tube expander apparatus bells and expands the open ends of heat exchanger hairpin tubes in a plate-fin heat exchanger unit. A frame supports belling jaw fingers which close over and the open ends of the tubes so that a belling device can enter the tube ends to urge the tube outward into a profile surface formed in the mating faces of the fingers. Also on the frame are mounted expander jaw fingers which close over tube ends which have been belled previously, and hold the associated hairpin tubes against axial movement while expander rods pass into the associated tube legs to urge the hairpin tube legs outward to contact against the fin plates and tube sheets of the fin pack heat exchanger. The belling fingers and belling device move step by step from one tube to another, and the expander gripping fingers and expander rods follow the belling fingers and belling device.