Internally finned tube having enhanced nucleation centers, heat exchangers, and methods of manufacture

Abstract

Tubing having internal fins projecting inward from the tube wall, each fin having an external surface that includes multiple acute interior angles or crevices that may form nucleation boiling sites, heat exchangers comprising such tubing, and methods of making same. Acute angles, crevices, or elongated slits may be formed in the sides, center, or both, of the fins or between the fins and the tube wall, and convex rounded surfaces may be provided therebetween. Fins may be parallel to the tube centerline or helically wound. Tubing may be expanded with a bullet which may form an interference fit with external fins, may modify the fins to create more effective nucleate boiling cavities, or both.

Description

CLAIM OF PRIORITY[0001]This patent application claims priority to, and incorporates by reference, U.S. provisional patent application 61 / 058,401 titled Internally Finned Tube Having Enhanced Nucleation Center, Heat Exchangers, and Air Conditioning Units, which was filed on Jun. 3, 2008.FIELD OF THE INVENTION[0002]This Invention relates to heat exchangers, including heat exchangers used in air conditioning units, and to methods and equipment for making heat exchangers.BACKGROUND OF THE INVENTION[0003]Heat exchangers have been used for some time to transfer heat from a warmer fluid to a cooler fluid, including in air conditioning units for cooling or heating (or both), spaces that people occupy, such as within buildings, vehicles, or the like. FIG. 1 illustrates an example of a heat exchanger 10 that may serve as an evaporator or a condenser in an air conditioning unit, for example, to transfer heat between a refrigerant and air, for instance.[0004]Refrigerant, which may be liquid, ga...

AI Technical Summary

Problems solved by technology

It is also known that partially closed cavities and crevices are even more effective than grooves, but, in the past, have been difficult to achieve in practice.

These grooves typically produce some increased heat-transfer performance in evaporators but little or no performance increase in condensers.

However, groves, notches, and the like, on the inside of the tube wall create stress concentration factors and reduce the pressure capacity of the tubing or may induce stress failures.

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