Heat-exchanger

[57] ABSTRACT

A heat-exchanger, particularly for mobile gas turbines, which is composed of lines, through which flows a first medium, and of a housing surrounding these lines through which flows a second medium, and which includes additionally a collecting space for the first medium that is subdivided by a partition wall into an inlet collecting space and an outlet collecting space, the two collecting spaces being connected with one or several chambers by way of the lines; the housing, in addition to surrounding the lines, further surrounds the collecting tank and is secured exclusively at the end faces thereof; the chambers are formed by the housing together with an apertured plate supported in rails.

Claims, 4 Drawing Figures

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Patented July 17, 1973

3,746,083

FIGI

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ATTORNEYS

3,746,083

HEAT-EXCHANGER

The present invention relates to a heat-exchanger, especially for movable gas turbines, which is composed of lines through which flows a first medium, and of a housing surrounding the lines, through which flows a second medium, and which further includes a collecting space for the first medium which is subdivided by a partition wall into an inlet collecting space and an outlet collecting space, which are connected with one or several chambers by way of the lines. Such types of heat-exchangers are thermally and mechanically highly loaded by high temperatures, large temperature differences between the inlet and the outlet of the gases and, above all, by the rapid and strong temperature fluctuations in case of load changes. The stresses produced thereby are still further enhanced by the rigid fastening of the collecting tank, of the chambers and of the apertured plates at the housing. In particular, the heatexchangers of mobile gas turbines are endangered thereby which require small dimensions and a slight weight and which therefore possesses only slight wall thicknesses of the lines.

It is the object of the present invention to eliminate these disadvantages and to produce a heat-exchanger 25 that is fully satisfactory as regards all thermal and mechanical loads. This is achieved according to the present invention in that the housing, in addition to surrounding the lines, also surrounds the collecting tank and is secured exclusively at the end faces thereof and ³θ together with apertured plates supported in rails further forms the chambers.

In this manner, the individual structural parts of the heat-exchangers can expand independently of one another corresponding to the differently strong heating ³⁵thereof so that dangerous stresses, as occur in particular at the connecting places, are avoided.

According to a further feature of the present invention, the housing surrounds the collecting tank in an advantageous manner under the formation of a gap which is closed off with respect to the housing space traversed by the second medium by sealing bars. In this manner, the rigid connection along the shell or casing, customary otherwise with an externally disposed collecting tank, is dispensed with. The stresses occurring thereby with unequal heating are avoided without the possibility that a part of the medium flowing through the housing space is able to by-pass the same.

According to a further feature of the present invention, the yieldingness and elasticity of the heatexchanger can be further increased in that an elastic intermediate element is arranged between one end face of the collecting tank and the housing, which compensates for the longitudinal expansions of the housing.

According to the present invention, the housing may be closed off by a divided cover disposed essentially in the plane of an end face of the collecting tank. This permits a very simple assembly of the heat-exchanger or the rapid disassembly thereof, for example, for purposes of cleaning.

Accordingly, it is an object of the present invention to provide a heat-exchanger which avoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a heat-exchanger, particularly for portable gas turbines, which is capable to withstand all thermal and mechanical loads and stresses occurring in the heat-exchanger.

A further object of the present invention resides in a light-weight and compact heat-exchanger that minimizes dangerous stresses in the various parts thereof.

Still another object of the present invention resides in a heat-exchanger in which the various parts are able to expand independently of one another according to their respective temperature without causing any excessive stresses.

Still another object of the present invention resides in a heat-exchanger which not only offers all the advantages mentioned above but is capable of simple assembly and rapid disassembly in case of need.

These and further objects, features, and advantages 15 of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein:

FIG. 1 is a longitudinal cross-sectional view through a first embodiment of a heat-exchanger in accordance with the present invention;

FIG. 2 is a transverse cross-sectional view through the heat-exchanger of FIG. 1;

FIG. 3 is a partial cross-sectional view, on an enlarged scale, illustrating certain details of FIG. 2; and

FIG. 4 is a transverse cross-sectional view, similar to FIG. 2, through a modified embodiment of a heatexchanger in accordance with the present invention.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, the pipe or tube heat-exchanger for a vehicle gas turbine illustrated schematically in FIGS. 1 and 2 essentially consists of a tube bundle or set of pipes generally designated by reference numeral 11, through which is conducted the air to be heated up, and of a housing 12 surrounding the same, through which flow the hot exhaust gases of the turbine. The housing 12 additionally surrounds a common or collecting tank 13 for the air and forms together with an apertured plate 15 supported in rails 14 a chamber 16 in which the air is deflected.

The collecting tank 13 has a cylindrical configuration and is subdivided by a partition wall 17 into an inlet collecting space 18 with an inlet aperture 19 and into an outlet collecting space 20 with an outlet aperture 21. The tube stack 11 is bent U-shaped and consists of a large number of tubes or pipes 22 of small diameter. The ends of the tubes or pipes 22 of the one leg 23 of ⁵θ the tube bundle 11 are connected with the inlet collecting space 18 whereas the ends of the tubes of the other leg 24 are connected with the outlet collecting space 20. The tubes 22 are guided with slight play or clear55 ance through the apertured plate 15 so that they are able to slide within the same. The bent part 25 of the tube set 11 is disposed in the chamber 16 whereas the legs 23 and 24 are exposed within the space 26 of the housing 12 to the exhaust gases. Reference numeral 27 ₆θ designates the inlet opening, and reference numeral 28 the outlet opening of the housing 12.

The housing 12 surrounds the collecting tank 13 under formation of a gap 29 which is closed off with respect to the space 26 of the housing 12 by elastic seal₆₅ ing bars 30. The sealing bars 30 have a U-profile (FIG. 3) whose one leg 31 is secured at the housing 12 and whose other leg 32 abuts at the casing or shell 33 of the collecting tank 13. Similar sealing bars 34 which abut

3,746,083 at the tubes 22 are arranged at the inner wall 35 of the chamber 16.

A cylindrically shaped elastic intermediate element 36 is arranged at the housing 12 within the area of the inlet aperture 19 of the collecting tank 13, which surrounds the inlet aperture 19 of the collecting tank 13. The housing 12 is closed off by a divided cover 37 mounted approximately in the plane of the outlet aperture 21 of the collecting tank 13. The housing 12 together with the cover 37 is secured at flanges 38 and 39 of the inlet aperture 19 and of the outlet aperture 21 by means of screws or bolts 40. Additionally, connecting pipes (not shown) may be secured at the flanges 38 and 39 by means of the same bolts 40.

As indicated by the arrows, the air to be heated flows through the inlet aperture 19 into the inlet collecting space 18 and from there through the legs 23 of the tube bundle 11. The air thereby absorbs heat from the hot exhaust gases flowing through the space 26 of the housing 12. After the reversal of the direction of flow in the chamber 16, the air absorbs additional heat in the legs 24 of the pipe set or tube bundle 11 and leaves thereupon the outlet collecting space 20 in the heated-up condition.

The differing temperatures prevailing at the individual places of the heat-exchanger lead to differently strong expansions of the housing 12, of the collecting tank 13 and of the tube bundle 11. By reason of the fact that the housing 12 is not fixedly welded to the casing or shell 33 of the collecting tank 13 but is merely threadably connected exclusively with the flanges 38 and 39 thereof by the use of an elastic intermediate element 36, none of the forces resulting from the thermal expansion can be transmitted from the housing 12 to the collecting tank 13 and to the tubes 22 of the tube bundle 11 connected therewith. Similarly, by reason of the support of the apertured plates 15 in rails 14, none of the forces can be transmitted from the housing 12 to the tubes 22. Stresses in the heat-exchanger which would lead to damages with the slight wall thicknesses conditioned by the light-weight type of construction, are avoided thereby.

In the heat-exchanger illustrated in FIG. 4, two mutually oppositely disposed sets or bundles of tubes 41 and 42 are connected with a central collecting tank 44 arranged within the housing 43 while reference numerals 45 and 46 designate chambers which are formed each by the housing 43 and by the apertured plates 49 and 50, respectively, supported in rails 47 and 48. Also in this case, the housing 43 is secured exclusively at the two end faces of the collecting tank 44. The operation of the embodiment of FIG. 4 corresponds otherwise to that of the heat-exchanger illustrated in FIGS. 1 to 3.

While I have shown and described only two embodiments in accordance with the present invention, it is understood that the present invention is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art. Thus, the present invention may also be applied to differently constructed heat-exchangers, for example, to such heat-exchangers in which air inlet and air outlet are disposed on the same side. Similarly, the present invention may also be applied to heat-exchangers having multiple cross-flows and combinations thereof. The aircollecting tank may have any suitable cross-sectional area, for example, an oval area. The tubes connected with the inlet collecting space and the outlet collecting space may discharge or terminate directly in the chamber formed by the housing and the apertured plate without the use of arcuate tube elements. Instead of tubes, the heat-exchanger may also include channels or 5 ducts which consist of correspondingly curved sheet metal plates connected with each other. The sealing bars may also be secured at the collecting tank instead of at the housing. They may also consist of labyrinth seals secured at the housing and at the collecting plate.

Thus, it is obvious that the present invention is susceptible of numerous changes and modifications without departing from the spirit and scope thereof, and I therefore do not wish to be limited to the details shown and described herein, but intend to cover all such 15 changes and modifications as are encompassed by the scope of the appended claims.