Corrugated Micro Tube Heat Exchanger

Abstract

A heat exchanger device having a plurality of substantially parallel tubes. Each tube has an outer diameter which is less than or equal to one millimeter and further includes a first end portion and a second end portion. A first manifold forms an inlet for the first fluid and further forms a plurality of first openings, whereby each of the first end portions of the parallel tubes is attached in a sealed manner to the first manifold so that each tube is in fluid communication with a respective one of the first openings. A second manifold spaced from and opposing the first manifold forms an outlet for the first fluid and further forms a plurality of second openings, whereby each of the second end portions of the parallel tubes is attached in a sealed manner to the second manifold so that each tube is in fluid communication with a respective one of the second openings. The plurality of substantially parallel tubes are laterally disposed relative to one another so that they form at least one corrugated pattern when viewed in an imaginary plane which intersects and is perpendicular to the longitudinal axes of the tubes.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 019,911, filed Jan. 9, 2008, the disclosure of which is incorporated herein by reference.TECHNICAL FIELD[0002]This invention relates to a heat exchanger device comprising corrugated micro tubes.BACKGROUND[0003]Heat exchangers transfer energy from one fluid to another. Heat exchangers are typically characterized by heat transfer rates and corresponding pressure drops of the fluid(s) across the heat exchanger. In many cases though, volume constraints are provided and, in these cases, heat exchanger performance may be characterized by heat transfer / flow area and corresponding pressure drops. For example, in the case of a liquid-gas heat exchanger, a typical design challenge is to minimize the face area associated with the gas side duct, while simultaneously meeting given specifications relating to allowable pressure drop of the gas across the heat exchanger, and, of course,...

AI Technical Summary

Benefits of technology

[0006]The present invention provides an efficient, simple, and cost-effective device and / or methodology to provide high heat transfer / pressure drop ratios that are needed by heat exchanger end users.

[0007]The present invention addresses a means to simultaneously achieve high heat transfer / unit duct area and low pressure drop by the use of a corrugated or serpentine field of closely packed micro tubes. The width of the corrugated field is much less than the total length of the serpentine. The serpentine provides effectively a frontal area much larger than the duct area for one fluid to pass through the heat exchanger. Because the area is larger, the velocity of the fluid passing over the serpentine tube bank is reduced compared to cases involving the same flow rate, same duct size, but no corrugation. The lower fluid velocity combined with the short flow length (equal to the width of the serpentine) results in low pressure drop of the fluid passing over the outside of the tube bank.

[0008]As noted above, the present invention comprises tightly packed micro tubes. Micro channel heat exchangers, in general, provide high heat transfer rates / volume compared to heat exchangers with larger, more conventional scale, heat exchange passageways. Heat transfer / unit area is a function of the product hA, where h is the convection coefficient and A is the area available for heat transfer. Because both h and A increase as the characteristic passageway dimension (width or diameter) decreases, the product of hA / unit volume for micro channel heat exchangers is much greater than heat exchangers with larger scale. Because micro channel heat exchangers need less volume to achieve a given rate of heat exchange, it becomes geometrically feasible to “reshape” this reduced volume into a thin, serpentine shape that affords advantages with respect to reducing pressure drop. The advantages associated with the serpentine shape simply disappear as the characteristic dimensions of the heat exchanger hardware are increased.

[0009]It should further be noted that fields of tightly packed micro tubes offer another advantage with respect to corrugated or serpentine hardware that dictate a specific flow direction (such as normal to the local tangent along the serpentine). As the depth of each crease of a serpentine increases for a given crease width, the need for the flow direction through the heat exchanger hardware to be nonspecific becomes more important. Heat exchangers that use a tube bank, which allow flow in any direction, tend to offer substantial advantages in corrugated arrangements over flow passage geometries that do not.

Problems solved by technology

For example, in the case of a liquid-gas heat exchanger, a typical design challenge is to minimize the face area associated with the gas side duct, while simultaneously meeting given specifications relating to allowable pressure drop of the gas across the heat exchanger, and, of course, heat transfer requirements.

Upon entering the volume occupied by the intertwining fluid passages, the fluid velocity typically increases because the hardware within the core that defines the two sets of fluid channels and promotes heat transfer between the two fluids necessarily occupies volume and restricts the area available for flow of both fluids.

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