Patent Application
20070137844
The invention relates to a plate heat exchanger comprising a heat exchanger block having a plurality of heat exchange passages, and a header attached to the heat exchanger block providing a flow connection between a portion of the heat exchange passages and a fluid connection, wherein the length of the header extends over at least one portion of a side of the heat exchanger block, and the header is defined by a cylinder jacket segment-shaped wall, and by a flat surface which runs parallel to the axis of the cylinder on the side of the heat exchanger block.
The general design of a plate heat exchanger is known from “The Standards of the Brazed Aluminum Plate-Fin Heat Exchanger Manufacturers' Association, ALPEMA,” Second Edition, 2000.
The heat exchanger block of a plate heat exchanger contains several layers of heat exchange passages, which are delimited from one another in each case by partitions. Cover strips as well as cover plates form the outer frame of the heat exchanger block. Additional separating edges that separate the heat exchange passages from one another for different substance flows can be provided within one layer.
Initially, the heat exchanger block is made of individual loose components which are then soldered in a soldering furnace, so that all components are tightly bonded to one another. Then, headers, which are provided with a fluid connection, are bonded via the inlet and outlet openings of the heat exchange passages. As headers, usually semi-cylindrical shells are used, but the headers can also have other shapes. The walls of the header generally form an exterior angle of 90° with the corresponding side of the block (see, for example, “The Standards of the Brazed Aluminum Plate-Fin Heat Exchanger Manufacturer's Association, ALPEMA,” Second Edition, 2000, FIGS. 1-5). A “fluid connection” is used for the entry of fluid into or the removal of fluid from the header. It is generally formed by a pipe socket, which is arranged in the semi-cylinder jacket of the header opposite the inlet or outlet openings; the pipelines for the incoming or outgoing streams of fluid are connected to these pipe sockets. Alternatively, the fluid connection can be arranged essentially perpendicular to the side of the heat exchanger block. In this arrangement, the connecting pipe extends the header, for example, over the edge of the block (see EP 1452817 A1, US 2005006076 A1, or U.S. Pat. No. 7,051,798) via which the header extends.
By a suitable arrangement of separating edges, plate heat exchangers can be used for the simultaneous heat exchange of many streams of fluid. For each of the streams of fluid, corresponding headers can then be provided via the respective inlet and outlet openings of the heat exchange passages and can be provided with pipelines (see, for example, “The Standards of the Brazed Aluminum Plate-Fin Heat Exchanger Manufacturer's Association, ALPEMA,” Second Edition, 2000, FIG. 1-1).
The term “side” of a heat exchanger block can be defined geometrically, i.e., it is an even surface of the heat exchanger block, which is generally designed in the shape of a parallelepiped. Generally, the “side” has a rectangular shape.
In headers used in plate heat exchangers, relatively high rates of flow often occur and cause a produce high pressure loss and/or an improper distribution of the fluid to the individual passages.
Therefore, one object of the invention is to provide a heat exchanger heaving improved flow characteristics within a header, particularly a header of a plate heat exchanger.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.
These objects are achieved by designing a header so that the axis of the cylinder runs inside the cylinder segment. The cross-section of the header is thus formed by more than one semi-circle. Its opening angle on the side of the heat exchanger is less than 180°.
The cylinder jacket segment-shaped wall of the heater thus forms an exterior angle with the side of the heat exchanger block that is smaller than 90°. “Exterior angle” is defined here as the angle that lies outside the header. For the case where the wall section of the header in question is bonded exactly to the edge of the block, this exterior angle is formed outward by the angle of the wall with the conceptual extension of the block side over this edge.
The non-vertical connection of the header wall with the block side has the effect that the cross-section of the flow in the header can be enlarged without having to increase, in this case, its base area facing the heat exchanger block. Thus, an improved flow characteristic within the header is achieved, which in turn produces a reduced pressure loss and a more uniform dispersion of the fluid in the passages.
For example, according to the invention, instead of a semi-cylinder, more than half of a cylinder jacket is used as a header. If the cylindrical axis of the header shifts from the side of the heat exchanger with a uniform diameter by about 10% of the cylinder diameter, the pressure loss can be reduced by about 35%. This advantage is achieved even with the same nominal width of the header (i.e., the same connecting dimensions and the same wall strength) and even reduced base area. Moreover, this eccentricity can be infinitely variable. In contrast to the variation of the nominal width, which is possible only in large steps, the flow cross-section of the header can thus be adapted in a directed fashion to the respective application, and in particular an improper distribution can be efficiently avoided.
Thus, in one aspect of the inventor, there is provided:
A plate heat exchanger comprising:
a heat exchanger block having a plurality of heat exchange passages; and
a header attached to the heat exchanger block providing a flow connection between a portion of the heat exchange passages and a fluid connection;
wherein the length of the header extends over at least one portion of a side of the heat exchanger block, and the header is defined by a cylinder jacket segment-shaped wall (7), and by a flat surface (12) which runs parallel to the axis (13) of the cylinder on the side of the heat exchanger block; and
wherein said axis (13) of said cylinder jacket (7) is spaced at a distance from said flat surface (12).
The distance between the axis (13) and the flat surface (12), will be sufficient to decrease the pressure loss in a comparable heat exchanger wherein the axis (13) is in the same plane as the flat surface (12).
The invention can also be applied to other header shapes, for example those with an oval, asymmetrical and/or square cross-section.
The exterior angle between the cylinder jacket segment-shaped wall of the header and the side of the heat exchanger block is preferably 87° or less, in particular 81° or less, in particular 75° or less, and is at least equal to 40°, in particular at least equal to 55°, and in particular at least equal to 65°.
The cylinder jacket segment-shaped wall (7) of the header (2) and/or the heat exchanger block are preferably produced from aluminum. In this case, the exchanger block is thus an aluminum plate heat exchanger, as it is basically described in, for example, “The Standards of the Brazed Aluminum Plate-Fin Heat Exchanger Manufacturer's Association, ALPEMA,” Second Edition, 2000. In this connection, it is advantageous if the cylinder jacket segment-shaped wall (7) of the header (2) and the heat exchanger block are connected to one another by friction, for example by a soldered or welded joint.
The entire disclosures of all applications, patents and publications, cited above and below and also including application's priority application EP 05026404.3 filed Dec. 2, 2005. are hereby incorporated by reference.
Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings wherein:
In the Figures, the following general features of the invention are shown: a heat exchanger block 1 (e.g., square), a header 2 configured according to the invention, a fluid connection 3, and a pipeline 4 that connected to the fluid connection 3. The header 2 shown in the Figures can be a fluid intake header or a fluid discharge header.
Of course, the plate heat exchanger according to the invention will have headers additional to the header shown in the individual Figures. These additional headers can be designed conventionally, or can be designed like the header according to the invention. Any combination of the headers according to the invention and conventional headers is possible within the scope of the invention.
As shown in, for example,
The axis of the cylinder 13, i.e., the axis of symmetry of the cylinder jacket 7, runs inside the header 2 at a distance 11 to the flat surface 12.
The two embodiments are distinguished by the orientation of the fluid connection 3. In
In the variant of
In an alternative embodiment of the invention, which is not shown in the drawings, the header 2 extends over the entire side 5 of the heat exchanger block. The two axial edges of the cylindrical wall of the header in this case run along two edges of the heat exchanger block.
The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05 026 404.3 | Dec 2005 | EP | regional |
