Carrier Corporation

Robert H Chiang

Jack Leon Esformes

Daniel P Gaffaney

Neelkanth S Gupte

Steven J Spencer

Edward A Huenniger

Albert J Kallfelz

Xin Liu

A vapor compression refrigeration system for cooling a liquid in which there is a spray dispenser for distributing liquid refrigerant over the tubes in a shell-and-tube type evaporator. The differential pressure in the refrigerant flow loop across the evaporator is the sole means of producing a flow through the spray dispenser. The evaporator is operated as a hybrid falling film heat exchanger, that is, in a semi-flooded condition. The lower portion of the evaporator shell is flooded with liquid refrigerant to wet the lower tubes in the tube bundle while the tubes in the upper portion are wetted only by refrigerant spray from the spray dispenser. The system is operated in a steady state condition whereby at least twenty-five percent (25%) of the tubes in the evaporator operate in a flooded heat transfer mode. The system allows a reduction in the amount of refrigerant charge in the system while at the same time avoiding the use of a recirculating system and pump.

Chiller with hybrid falling film evaporator

An improved heat transfer tube for use in air conditioning chillers of the shell and tube type. The tube (10) achieves objectives of improved manufacturability, heat transfer performance and fluid flow characteristics by having external helical fins (12) with specified ranges of fin heights and fin density for a specified range of tube outer diameters.

Heat transfer tube

A heat transfer tube having an internal surface that enhances the heat transfer performance of the tube. Helical ribs project from the internal surface of the tube. The ribs have a pattern of parallel notches intersecting and impressed into them at a small angle of inclination with respect to the longitudinal axis. The pattern of ribs and notches increase the total internal surface area of the tube and also promote conditions for the flow of refrigerant within the tube that increase heat transfer performance. The tube is suitable for use in both refrigerant evaporators and condensers.

A tube for use in a heat exchanger where heat is transferred between a fluid flowing through the tube and a fluid flowing around the exterior of the tube and where the fluid external to the tube boils during the heat exchange process. The tube has one or more external fin convolutions extending from its external surface. At intervals along each side surface of the fin convolutions there are shoulder notches extending from the fin side surfaces. The groove space between adjacent fin convolutions has raised teeth located circumferentially at intervals. The fin convolutions do not extend perpendicularly from the tube surface but are inclined, with one convolution overlying an adjacent groove but not touching its adjacent neighbor fin convolution to form a re-entrant boiling cavity with an opening gap. In one embodiment, the opening gap extends completely around the circumference of the tube. In another embodiment, the curved fin convolutions are depressed at intervals around the circumference of the tube so that a fin convolution is in close proximity to its adjacent neighbor closing the gap in the vicinity of the depression.

Heat exchanger tube

A heat exchanger tube having an internal surface that enhances the heat transfer performance of the tube. The internal surface has ribs that run substantially parallel to the longitudinal axis of the tube. The ribs have a pattern of parallel notches intersecting and impressed into them at an angle oblique to the longitudinal axis. The pattern of ribs and notches increase the total internal surface area of the tube and also promote conditions for the flow of refrigerant within the tube that increase heat transfer performance.

A heat exchanger tube (10) for use in an application, such as a shell and tube type air conditioning system condenser, in which a fluid flowing through the heat exchanger external to the tubes condenses by transfer of heat to a cooling fluid flowing through the tubes. The tube has at least one fin convolution (22) extending helically around its external surface (13). Multiple axial notches (23) are impressed into the fin at intervals along its extent. Because the notches are impressed and not cut into the fin, material displaced from a fin to form a notch forms lateral projections (24) from the the walls of the fin. The notched fins provide increased external heat transfer surface area on the tube, destabilize the film of condensate on the tube external surface, thus causing the film to be generally thinner, and promote condensate drainage from the fins and off the tube and thus increase the heat transfer performance of the tube.

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Liverpool, NY, United States of America

Robert H Chiang