Evaporative heat exchange apparatus with finned elliptical tube coil assembly

Abstract

An improved finned coil tube assembly enhances evaporative heat exchanger performance, and includes tubes, preferably serpentine tubes, in the coil assembly. The tubes have a generally elliptical cross-section with external fins formed on an outer surface of the tubes. The fins are spaced substantially 1.5 to substantially 3.5 fins per inch (2.54 cm) along the longitudinal axis of the tubes, extend substantially 23.8% to substantially 36% of the nominal tube outside diameter in height from the tubes outer surface and have a thickness of substantially 0.007 inch (0.018 cm) to substantially 0.020 inch (0.051 cm). The tubes have a center-to-center spacing generally horizontally and normal to the longitudinal axis of the tubes of substantially 109% to substantially 125% of the nominal tube outside diameter, and a generally vertical center-to-center spacing of substantially 100% to about 131% of the nominal tube outside diameter.

1 - 38 . (canceled) 
     
     
         39 . An evaporative indirect heat exchanger comprising:
 a plenum having a generally vertical axis,   a coil assembly,   a distributor for distributing an external heat exchange liquid onto a coil assembly, an air mover for causing air to flow in a direction through the plenum, and   said coil assembly mounted within the plenum such that the external heat exchange liquid flows externally through the coil assembly in a generally downward vertical flow direction, and the air flows externally through the coil assembly interacting with the external heat exchange liquid to evaporate and cool the external heat exchange liquid and internal process fluid within the coil assembly,   wherein the coil assembly comprises inlet and outlet manifolds and a plurality of tubes connecting the manifolds, each tube comprising a plurality of horizontally oriented segments arranged vertically relative to one-another in a single vertical plane, wherein each segment has a longitudinal axis and a generally elliptical cross-sectional shape having a major axis and a minor axis where the average of the major axis length and the minor axis length is a nominal tube outside diameter, and where the major axis of each segment of a tube is aligned with the single vertical plane,   wherein the tubes are arranged in the coil assembly in a staggered arrangement of a first and second set of alternating tubes in which each tube in said first set of tubes is fixed in the coil assembly at a first vertical position, and each of said second set of alternating tubes is fixed in the coil assembly at a second vertical position which is displaced from said first vertical position, wherein the tubes have external elliptical spiral fins on an outer surface of the tubes, wherein the fins have:
 a spacing of 1.5 to 3.5 fins per inch (2.54 cm) along the longitudinal axis of the tubes, 
 a height extending from the outer surface of the tubes a distance of substantially 23.8% to substantially 36% of the nominal tube outside diameter, and 
 a thickness of substantially 0.007 inch (0.018 cm) to substantially 0.020 inch (0.051 cm), wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 100% to substantially 131% of the nominal tube outside diameter, and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 110% to substantially 300% of the nominal tube outside diameter. 
   
     
     
         40 . An evaporative heat exchanger according to  claim 39 , wherein the fins have a spacing of substantially 2.75 to substantially 3.25 fins per inch (2.54 cm) along the longitudinal axis of the tubes. 
     
     
         41 . An evaporative heat exchanger according to  claim 40 , wherein the fins have a spacing of substantially 3 fins per inch (2.54 cm) along the longitudinal axis of the tubes. 
     
     
         42 . An evaporative heat exchanger according to  claim 39 , wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 106% to substantially 118% of the nominal tube outside diameter. 
     
     
         43 . An evaporative heat exchanger according to  claim 42 , wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 112% of the nominal tube outside diameter. 
     
     
         44 . An evaporative heat exchanger according to  claim 39 , wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 150% to substantially 205% of the nominal tube outside diameter. 
     
     
         45 . An evaporative heat exchanger according to  claim 44 , wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 179% of the nominal tube outside diameter. 
     
     
         46 . An evaporative heat exchanger according to  claim 39 , wherein the nominal tube outside diameter is substantially 1.05 inches (2.67 cm). 
     
     
         47 . An evaporative heat exchanger according to  claim 39 , wherein the fins have a spacing of substantially 2.75 to substantially 3.25 fins per inch (2.54 cm) along the longitudinal axis of the tubes, a height of substantially 28% to substantially 33% of the nominal tube outside diameter, a thickness of substantially 0.009 inch (0.023 cm) to substantially 0.015 inch (0.038 cm), wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 106% to substantially 118% of the nominal tube outside diameter, and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 150% to substantially 205% of the nominal tube outside diameter. 
     
     
         48 . An evaporative heat exchanger according to  claim 47 , wherein the nominal tube outside diameter is substantially 1.05 inches (2.67 cm). 
     
     
         49 . An evaporative heat exchanger according to  claim 39 , wherein the fins have a spacing of substantially 3 fins per inch (2.54 cm) along the longitudinal axis of the tubes, a height of substantially 29.76% of the nominal tube outside diameter, a thickness of substantially 0.01 inch (0.025 cm) to substantially 0.013 inch (0.033 cm), and wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is about 112% of the nominal tube outside diameter, and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is about 179% of the nominal tube outside diameter. 
     
     
         50 . An evaporative heat exchanger according to  claim 49 , wherein the nominal tube outside diameter is substantially 1.05 inches (2.67 cm). 
     
     
         51 . An evaporative heat exchanger according to  claim 39 , wherein the nominal tube outside diameter is substantially 1.05 inches (2.67 cm), wherein the fins have a center-to-center spacing of substantially 0.286 inch (0.726 cm) to substantially 0.667 inch (1.694 cm), a height of substantially 0.25 inch (0.635 cm) to substantially 0.375 inch (0.953 cm), and wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 1.05 inches (2.67 cm) to substantially 1.38 inches (3.51 cm), and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 1.15 inches (2.92 cm) to substantially 3.15 inches (8.00 cm). 
     
     
         52 . An evaporative heat exchanger according to  claim 51 , wherein the fins have a center-to-center spacing of substantially 0.308 inch (0.782 cm) to substantially 0.364 inch (0.925 cm), a height of substantially 0.294 inch (0.747 cm) to substantially 0.347 inch (0.881 cm), a thickness of substantially 0.009 inch (0.023 cm) to substantially 0.015 inch (0.038 cm), and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 1.57 inches (3.99 cm) to about 2.15 inches (5.46 cm). 
     
     
         53 . An evaporative heat exchanger according to  claim 52 , wherein the fins have a center-to-center spacing of substantially 0.333 inch (0.846 cm), a height of substantially 0.3125 inch (0.794 cm), a thickness of substantially 0.01 inch (0.025 cm) to substantially 0.013 inch (0.033 cm), and wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 1.175 inches (2.985 cm), and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to adjacent tubes in said second set of tubes by a distance (DV) that is substantially 1.88 inches (4.78 cm). 
     
     
         54 . An evaporative heat exchanger according to  claim 39 , wherein the major axes of the tubes are generally parallel to the vertical axis of the plenum. 
     
     
         55 . An evaporative heat exchanger according to  claim 39 , wherein the fins have undulations in and out of a plane of material used to make the fins, wherein the undulations extend from an inner radius of the fins toward but not to an outer radius of the fins. 
     
     
         56 . An evaporative heat exchanger according to  claim 39 , wherein the finned tubes are galvanized such that the fins after galvanization are thicker at a base proximal to the outer surface of the tube than at a tip of the fins distal from the outer surface of the tube. 
     
     
         57 . An evaporative heat exchanger according to  claim 39 , wherein the tubes are serpentine tubes having a plurality of segments and a plurality of return bends, wherein the return bends are oriented in generally vertical planes, the segments of each tube connecting the return bends of each tube and extending between the return bends in a direction generally horizontally. 
     
     
         58 . An evaporative heat exchanger according to  claim 57 , wherein the return bends have a circular cross-section with an outside diameter of substantially 1.05 inches (2.67 cm) and wherein the nominal tube outside diameter is substantially 1.05 inches (2.67 cm). 
     
     
         59 . An evaporative heat exchanger according to  claim 57 , wherein the return bends have a generally elliptical cross-section and the nominal tube outside diameter of substantially 1.05 inches (2.67 cm). 
     
     
         60 . An evaporative heat exchanger according to  claim 57 , wherein the major axes of the segments are generally parallel to the plane of the return bends. 
     
     
         61 . An evaporative heat exchanger according to  claim 57 , the fins having a spacing of substantially 2.75 to substantially 3.25 fins per inch (2.54 cm) along the longitudinal axis of the segments, the fins having a height of substantially 28% to substantially 33% of the nominal tube outside diameter, the fins having a thickness of substantially 0.009 inch (0.023 cm) to substantially 0.015 inch (0.038 cm), wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 106% to substantially 118% of the nominal tube outside diameter, and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to each of said tubes in said second set of tubes by a distance (DV) that is 150% to substantially 205% of the nominal tube outside diameter. 
     
     
         62 . An evaporative heat exchanger according to  claim 57 , the fins having a spacing of substantially 3 fins per inch (2.54 cm) along the longitudinal axis of the segments, the fins having a height of substantially 29.76% of the nominal tube outside diameter, the fins having a thickness of substantially 0.01 inch (0.025 cm) to substantially 0.013 inch (0.033 cm), wherein each of the tubes of said first or second set of alternating tubes is horizontally spaced, center-to-center, from an adjacent tube in a same set of alternating tubes by a distance (DH) that is substantially 112% of the nominal tube outside diameter, and wherein each of the tubes in said first set of tubes is vertically displaced, center-to-center, relative to each of said tubes in said second set of tubes by a distance (DV) that is substantially 179% of the nominal tube outside diameter.