Condenser with small hydraulic diameter flow path
First Claim
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1. A condenser comprising:
- a pair of spaced headers arranged to have a vapor inlet and a condensate outlet;
a plurality of tubes extending in hydraulic parallel between said headers, each in fluid communication with each of said headers;
said tubes having a plurality of discrete hydraulically parallel capillary fluid flow paths between said headers;
each of said fluid flow paths being noncircular in cross section and having at least one elongated crevice extending along the length thereof;
the hydraulic diameter of each of said flow paths being sufficiently small that surface tension in condensate in said crevice will create an area of relatively lower pressure thus causing a pressure differential whereby condensate in a film elsewhere in said flow path will flow by operation of said pressure differential to said crevice;
said hydraulic diameter being in the range of about 0.015 to 0.040 inches, said hydraulic diameter being the cross-sectional area of the corresponding flow path multiplied by four and divided by the wetted perimeter of the corresponding flow path; and
,said flow paths having surfaces subjected to vapor and condensate and including microcracks.
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Abstract
An improved condenser for use in air conditioning or refrigeration systems. A pair of spaced headers have a plurality of tubes extending in hydraulic parallel between them and each tube defines a plurality of hydraulically parallel, fluid flow paths between the headers. Each of the fluid flow paths has a hydraulic diameter in the range of about 0.015 to about 0.04 inches. Preferably, each fluid flow path has an elongated crevice extending along its length to accumulate condensate and to assist in minimizing film thickness on heat exchange surfaces through the action of surface tension. Heat exchange surfaces may also be provided with microcracks or channels to enhance heat transfer.
101 Citations
10 Claims
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1. A condenser comprising:
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a pair of spaced headers arranged to have a vapor inlet and a condensate outlet; a plurality of tubes extending in hydraulic parallel between said headers, each in fluid communication with each of said headers; said tubes having a plurality of discrete hydraulically parallel capillary fluid flow paths between said headers; each of said fluid flow paths being noncircular in cross section and having at least one elongated crevice extending along the length thereof; the hydraulic diameter of each of said flow paths being sufficiently small that surface tension in condensate in said crevice will create an area of relatively lower pressure thus causing a pressure differential whereby condensate in a film elsewhere in said flow path will flow by operation of said pressure differential to said crevice; said hydraulic diameter being in the range of about 0.015 to 0.040 inches, said hydraulic diameter being the cross-sectional area of the corresponding flow path multiplied by four and divided by the wetted perimeter of the corresponding flow path; and
,said flow paths having surfaces subjected to vapor and condensate and including microcracks. - View Dependent Claims (2, 3)
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4. A condenser comprising:
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a pair of spaced headers including a vapor inlet and a condensate outlet; a plurality of tubes extending in hydraulic parallel between said headers, each in fluid communication with each of said headers; said tubes having a plurality of discrete, hydraulically parallel fluid flow paths between said headers, each said flow path having a noncircular, nominally triangular cross section to define a plurality of crevices for each such flow path; said tubes being flattened tubes; each of said fluid flow paths having a hydraulic diameter in the range of 0.015 inches to 0.040 inches, said hydraulic diameter being the cross-sectional area of the corresponding flow path multiplied by four and divided by the wetted perimeter of the corresponding flow path; said fluid flow paths being defined by a spacer within each of said tubes and brazed thereto; and
,said spacers and/or said tubes having a coating of residual brazing flux defining microcracks.
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5. A condenser comprising:
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a pair of spaced headers including a vapor inlet and a condensate outlet; a plurality of tubes extending in hydraulic parallel between said headers, each in fluid communication with each of said headers; said tubes having a plurality of discrete, hydraulically parallel fluid flow paths between said headers, each said flow path having a noncircular, nominally triangular cross section to define a plurality of crevices for each such flow path; each of said fluid flow paths having a hydraulic diameter in the range of 0.015 to 0.040 inches, said hydraulic diameter being the cross-sectional area of the corresponding flow path multiplied by four and divided by the wetted perimeter of the corresponding flow path; each of said fluid flow paths having a surface provided with microcracks.
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6. A condenser comprising:
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a pair of spaced headers; one of said headers having a vapor inlet; one said headers having a condensate outlet; and a plurality of tubes extending in hydraulic parallel between said headers, each in fluid communication with each of said headers; said tubes having a plurality of discrete hydraulically parallel fluid flow paths between said headers; each of said fluid flow paths having at least one elongated crevice and an internal surface provided with microcracks, each of said fluid flow paths further having a sufficiently small hydraulic diameter so that surface tension and capillary forces acting upon condensate within said flow paths improve heat transfer efficiency of said condenser, said hydraulic diameter being the cross-sectional area of the corresponding flow path multiplied by four and divided by the wetted perimeter of the corresponding flow path. - View Dependent Claims (7, 8)
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9. A condenser for a refrigerant in a cooling system comprising:
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a pair of spaced, generally parallel, elongated cylindrical tubes defining headers; a vapor inlet in one of said tubes; a condensate outlet from one of said tubes; said header tubes each having a series of elongated generally parallel slots with the slots in the series on one header tube aligned with and facing the slots in the series on the other header tube; a tube row defined by a plurality of straight, tubes of flat cross-section and with flat side walls and having opposed ends extending in parallel between said header tubes, the ends of said flat cross section tubes being disposed in corresponding aligned ones of said slots and in fluid communication with the interiors of said header tubes, at least some of said tubes being in hydraulic parallel with each other; web means within said flat cross-section tubes and extending between and joined to the flat side walls at spaced intervals to (a) define a plurality of discrete, hydraulically parallel flow paths within each flat cross-section tube that extend between said header tubes;
to (b) absorb forces resulting from internal pressure within said condenser and tending to expand the flat cross-section tubes; and
to (c) conduct heat between both said flat sides and fluid in said flow paths, said flow paths being of relatively small hydraulic diameter which is defined as the cross-sectional area of the corresponding flow path multiplied by four (4) and divided by the wetted perimeter of the corresponding flow path;serpentine fins incapable of supporting said flat cross-section tubes against substantial internal pressure extending between facing flat side walls of adjacent flat cross-section tubes; each of said flow paths including at least one elongated crevice extending generally along the length of the associated flow path. - View Dependent Claims (10)
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Specification