Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Reexamination Certificate
1998-09-15
2001-02-27
Lazarus, Ira S. (Department: 3743)
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
C165S157000, C165S163000
Reexamination Certificate
active
06192974
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to heat exchangers. More specifically, the present invention relates to transition members forming the inlets and outlets to rectangular heat exchanger housings which contain finned heat exchanger coils.
BACKGROUND OF THE INVENTION
Heat exchangers designed for cooling and heating gases at pressures less than 3 atmospheres are widely used and well suited to finned heat exchanger coils. Such heat exchangers are used, for example, to cool gases used to carry grains into or out of storage bins, grain elevators, and rail cars. If the gases are not at the proper temperature, molding can occur, as can other problems associated with temperature and pressure.
Traditionally, many finned heat exchanger coils and housings for such applications have been rectangular in cross section, and nearly all pressurized gas flows into and out of the housing through gas carrier lines that have a round cross section. Industry practice has been to build heat exchanger housings that have square-to-round transitions in order to direct gases from the round carrier lines into the rectangular exchanger housing body.
The square-to-round transitions traditionally used have a first end that is generally square or rectangular and a second end that is generally round. This square or rectangular end of the transition has four distinct sides, plus four corners, and fastens to the rectangular housing. These four sides usually gradually round off to a circle at the second end of the transition. This circular second end connects to the circular gas carrier line.
Unfortunately, these existing square-to-round transitions used in such heat exchanger systems are problematic because they suffer from a number of draw backs. In particular, the four flat areas must be sufficiently thick and strong enough to avoid deformation and deflection when under pressure. Alternatively the flat areas must be reinforced in order to maintain the shape of the transition member within proper tolerances. If these flat areas display two much deflection, undue stress is transferred to the corners of the transitions, which suffer metal fatigue and fail.
Not only are these square-to-round transitions troublesome due to the fact that they are prone to failure if not constructed of sufficiently strong materials, they are also relatively difficult to make due to the fact that multiple bends must be made and reinforcing strips must be installed. These bends can add cost to the manufacture of the transition members because they require additional labor, and the reinforcing strips add cost by requiring additional material as well as additional labor.
Therefore, a need exists for an improved heat exchanger housing and transition that overcomes the aforementioned problems associated with present housings and transitions.
SUMMARY OF THE INVENTION
The present invention is directed to a heat exchanger housing containing a finned heat exchanger coil. The heat exchangers of the present invention are used to heat or cool gases as they pass through the housing. In certain implementations, the finned heat exchanger coil carries a cold fluid that cools the gases as they pass through the housing. In other implementations, the finned heat exchanger coil carries a hot fluid that heats the gases as they pass through the housing.
In certain implementations of the invention, the heat exchanger housing includes a substantially rectangular body. On the exterior of the heat exchanger housing is placed an inlet and an outlet. In specific implementations, the inlet and the outlet are positioned on opposite sides of the rectangular body. The inlet and outlet are each substantially circular. Joined to these substantially circular inlets and outlets are conical transition portions that join to circular carrier lines. The carrier lines direct gases toward or away from the heat exchanger housing. Conical transitions provide a way to direct the gases from the circular carrier lines into the rectangular exchanger housing with a minimum of difficulty and with increased efficiency. Problems from metal fatigue at the corners, as used by prior art transfer members, are also avoided.
In certain embodiments, the housing of the heat exchanger has first and second generally planar metallic walls. Both of these walls are substantially rectangular, and are positioned parallel to one another at opposite sides of the housing. The first and second walls each contain a substantially circular opening to which is connected a conical transition member. The openings are substantially opposite one another. A first conical metallic transition member is connected to the first circular opening in the first wall. This conical transition member tapers from the circular opening to a narrowed end distal from the first wall of the housing. In addition, a second conical metallic transition member is connected to the second substantially circular opening in the second wall. The second conical transition member tapers to a smaller circle distal from the second wall.
Unlike prior art transitions used for low-pressure applications to connect a round carrier line to a square or rectangular housing, the conical transition members of the present invention do not contain corners or creases. The lack of such corners and creases increases the strength of the transition members. In addition, the conical transition members lack planar or flat portions. Therefore, without these flat surfaces, the conical transition members undergo less deformation under pressure.
In certain implementations of the invention, third and fourth substantially planar rectangular walls are provided on the exchanger housing. The third and forth walls are positioned perpendicular to and intermediate the first and second walls, thereby defining a four-sided rectangular arrangement having a rectangular front edge and an opposite rectangular rear edge, the four-sided rectangular arrangement has an interior intermediate the walls of the arrangement.
A front flange and a rear flange are secured to, or integrally formed with, the rectangular arrangement. The front flange is proximate the front edge of the rectangular arrangement and the rear flange is proximate the rear edge of the rectangular arrangement. The front and rear flanges each include a protruding lip extending from the sides of the rectangular arrangement away from the interior. Each protruding lip contains a plurality of openings configured to receive a fastener.
Additionally, in certain embodiments, a front cover plate is joined to the front flange of the rectangular arrangement and a rear cover plate is joined to the rear flange of the rectangular arrangement. A finned heat exchanger coil is positioned within the heat exchanger housing, the finned heat exchanger coil preferably having a substantially rectangular cross section.
The above summary of the present invention is not intended to describe each disclosed embodiment of the present invention. This is the purpose of the figures and the detailed description which follow.
REFERENCES:
patent: 4083400 (1978-04-01), Dziedzic et al.
Company Brochure, “Xchanger, Inc.: Heat Exchangers, Standard Designs, Custom Designs, Since 1972”,Xchanger, Inc., pp. 1-9 (1994).
Lazarus Ira S.
McKinnon Terrell
Merchant & Gould P.C.
Xchanger, Inc.
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