Bent tube heat exchanger assembly

Abstract

A heat exchange unit for a heat exchanger assembly is provided for use in a cooling system of a CT imaging system having a gantry frame with an annular interior region. The heat exchange unit is formed of a plurality of tubes bent at discrete locations to divide the tubes into straight leg sections to fit within an arcuate portion of the gantry frame's annular region. The bent tubes are maintained between a pair of tube sheets in an array with the straight leg sections parallel and the bends generally radially aligned. The tubes are orthogonally joined to the tube sheets, and the faying surfaces are flat and parallel, leading to a dependable joint. The heat exchanger assembly includes mounting brackets with mounting fixtures axially aligned with the gantry frame, to reduce stress on the fasteners and the mounting brackets.

1 . A heat exchange unit for a heat exchanger assembly for use in a gantry frame having an annular interior region, comprising:
 a plurality of tubes having open ends and flat exterior upper and lower surfaces, flow passages for a first heat exchange fluid extending through the interior of the tubes;   each of the tubes having at least one bend formed at discrete locations to divide each of the tubes into a plurality of straight leg sections configured to fit within an arcuate portion of the annular interior region; and   a pair of tube sheets disposed to maintain the tubes in an array with each of the straight leg sections of adjacent tubes maintained in parallel and the bends generally radially aligned, the tubes spaced apart a distance to allow fluid flow of a second heat exchange fluid between the flat exterior surfaces of the tubes, and the tubes attached to the tube sheets at end portions adjacent the open ends.   
     
     
         2 . The heat exchange unit of  claim 1 , wherein the bends in the tubes are located symmetrically about a centerline through an arc tangent to the tubes at the centerline and at points where the tubes join the tube sheets. 
     
     
         3 . The heat exchange unit of  claim 1 , wherein the end portions of the tubes are joined to the tube sheet perpendicular to surfaces of the tube sheets. 
     
     
         4 . The heat exchange unit of  claim 1 , wherein faying surfaces of the tubes and the tube sheets are flat and parallel. 
     
     
         5 . The heat exchange unit of  claim 1 , wherein the flat exterior upper and lower surfaces of the tubes at the end portions are parallel to surfaces of slots formed in the tube sheets where the end portions are attached to the tube sheets. 
     
     
         6 . The heat exchange unit of  claim 1 , wherein the tubes are attached to the tube sheets by brazed joints, welded joints, or a combination of brazed and welded joints. 
     
     
         7 . A heat exchanger assembly for use in a gantry frame having an interior region that extends annularly about an axial direction, comprising:
 the heat exchange unit of  claim 1 ;   mounting brackets attached to opposite sides of the heat exchange unit adjacent the tube sheets, the mounting brackets including mounting fixtures for attachment to the gantry frame; and   fluid inlet and outlet fittings disposed on one or both of the mounting brackets.   
     
     
         8 . The heat exchanger assembly of  claim 7 , wherein the mounting fixtures of the mounting brackets extend in the axial direction of the gantry frame. 
     
     
         9 . The heat exchanger assembly of  claim 8 , wherein the mounting fixtures include extending ear portions, apertures in the extending ear portions aligned with the axial direction to receive fastener members therethrough.