Heat exchange – Non-communicating coaxial enclosures
Patent
1984-08-20
1985-11-26
Richter, Sheldon J.
Heat exchange
Non-communicating coaxial enclosures
165 70, 165161, F28D 710, F28F 922, F28F 1306
Patent
active
045549699
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a coaxial finned tube heat exchanger.
Heat exchangers of the type including a hollow shell and one or a plurality of smooth tubes arranged interiorly of the shell are well known. Generally, a heating or cooling fluid flows through the tubes whereas the fluid to be heated or cooled flows through the shell and impinges the outside surface of the tubes. With heat exchangers having a plurality of tubes, baffles are normally arranged inside the shell for changing the direction of flow of the fluid to be heated or cooled to improve heat transfer.
The present invention concerns a special type of heat exchanger for heating or cooling viscous fluids and gases and finds specific application in heating or cooling heat transfer oils, hydraulic oils and lubricating oils as well as heating or cooling gases, such as air, nitrogen or the like. Oils and gases have poor heat transfer characteristics relative to say water. This is generally compensated for by using more heat transfer surface which normally means larger, more costly heat exchangers. Conventional shell and multi-smooth tube exchangers have a relatively low capacity level to house heat transfer surface. The ratio of heat transfer area to total volume does not generally exceed 100 ft.sup.2 /ft.sup.3.
It is therefore the object of the present invention to provide a heat exchanger for oils and gases having a higher ratio of heat transfer area to total volume.
The coaxial heat exchanger, in accordance with the present invention, comprises a hollow shell, a tube mounted coaxially within the shell and having radially extending outer fins of substantially large radial dimension in relation to the tube diameter, means for passing a first heat exchange fluid in the tube, means for passing a second heat exchange fluid through the shell, a plurality of segmental cut baffles mounted between adjacent fins at a predetermined spacing within the shell so as to achieve a cross flow pattern for the second fluid between the fins of the tubes, and a pair of bypass flow blockers mounted longitudinally on the tip of the fins to block circumferential flow of the second fluid between the shell and the tip of the fins and so force the fluid flow between the fins.
The baffles are spaced at predetermined intervals according to the heat transfer application. The space between the shell and the tip of the fins is also according to the application.
The bypass flow blockers are preferably a pair of rods or strips attached to the fin tips at the cut points of the baffles.
The tube is preferably provided with internal fins or other internal tube augmentation schemes, but it may also be smooth on the inside. A second tube may be inserted inside the finned tube and suitable grooves or protuberances provided on the inside surface of the finned tube or the outside surface of the second tube for leakage detection. Such second tube may be provided with internal fins or other internal tube augmentation schemes.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
FIG. 1 illustrates a schematic view of a heat exchanger in accordance with the invention;
FIG. 2 illustrates a view along line 2--2 of FIG. 1;
FIG. 3 illustrates a perspective view of the tube of the heat exchanger in accordance with the invention;
FIGS. 4 and 5 show the results of tests made upon cooling Brayco 888 oil and a 50% mixture of glycol/water, respectively, with the heat exchanger in accordance with the invention; and
FIG. 6 shows a heat exchanger in accordance with the invention provided with leak detection.
Referring to FIG. 1, there is schematically shown an embodiment of a heat exchanger in accordance with the invention. The heat exchanger comprises a hollow shell 10 which is closed at both ends and provided with a shell fluid inlet 12 at one end and a shell fluid outlet (not shown) at the other end. A tube 14 provided with radially extending outer fins 16 of substantially large radial dimension in relation to the tube diameter, preferably in a
REFERENCES:
patent: 830248 (1906-09-01), Von Orth
patent: 928063 (1909-07-01), Moneuse
patent: 3335655 (1967-08-01), McCuiston
patent: 4228848 (1980-10-01), Wadkinson, Jr.
Noranda Metal Industries, Inc.
Richter Sheldon J.
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