HEAT EXCHANGING DEVICE

Abstract

A heat exchanging device (2), in particular a fluid/air heat exchanger, having individual fluid-conducting collecting chambers (6, 10) which in each case have an inlet (8) or outlet (12) for fluid supply and discharge and which are connected to one another via duct-like fluid guides (14) which control the temperature of, in particular cool, a fluid flow during operation of the device by means of an air flow which flows in duct-like air guides which are separated from the fluid guides (14) in a medium-tight manner, is characterized in that, in order to construct the overall heat exchanging device (2), at least one further collecting chamber (18; 20, 22) is inserted between collecting chambers (6, 10) which are arranged on outer sides which lie opposite one another, which further collecting chamber (18; 20, 22) is arranged parallel to the collecting chambers (6, 10) which lie on the outside, and into which further collecting chamber (18; 20, 22) all the fluid guides (14) which are connected to a collecting chamber (6, 10) which lies on the outside likewise open.

Description

The invention relates to a heat exchanging device, in particular a fluid/air heat exchanger, having individual fluid-conducting collecting chambers, which in each case have an inlet or outlet for fluid supply and discharge and which are connected to one another via duct-like fluid guides which control the temperature of, in particular cool, a fluid flow during operation of the device by means of an air flow which flows in duct-like air guides which are separated from the fluid guides in a medium-tight manner.

Heat exchanging devices of this type, which are also referred to as finned coolers, are state of the art. With air as the cooling medium, such heat exchangers are often used for cooling hydraulic fluids for the working hydraulics of mechanical systems, such as construction machines or the like, for hydrostatic drive units or as oil coolers for heavily loaded gears, specifically in wind power stations. The document DE 10 2010 056 567 A1 shows an example of the application of such a heat exchanger in a fluid/air cooling system to generate a cooling capacity for the hydraulic fluid in the hydraulic working circuit of an associated machine unit. During operation of such systems, the heat exchangers are subject to not only mechanical stresses, but they are also subject to thermal stresses in particular, due to the great range of temperatures which can arise at the system components during operation. Such stresses result both from the operating temperatures of the media involved, such as air and fluid, and from the influences of the ambient temperatures at the place of application of the heat exchangers, for example due to the climatic conditions at the place of application.

In the case of heat exchangers in the form of so-called finned coolers with a conventional design which, as is revealed in DE 10 2010 046 913 A1, are made up of a bundle of plates lying on top of one another, between which duct-like air guides and fluid guides are alternately formed, it is possible that, for example at high operating temperatures of the fluids resulting from swings in temperature of the type that occur in intermittent operation, stresses can occur in the bundle of components due to longitudinal expansion. Possible consequences include stress cracks in the bundle, which is joined together by means of soldering to form a rigid block, in particular in the region of the soldered seams, accompanied by the danger of a malfunction of the heat exchanger and thus compromising the associated system. In order to avoid this, it is known from the mentioned document DE 10 2010 046 913 A1 to give the strips forming the soldering surfaces on the plates a special profile shape, which leads to an approximately linear change in the bending strength of the shanks of the profile, so that an optimal bending behavior of the shanks is obtained and the risk of stress cracks at the soldering regions is minimized.

While the risk of interruption of operation in the case of swings in temperature over high temperature ranges is thus effectively avoided, problems can develop due to low temperatures arising at the heat exchanger. This is the case namely when corresponding systems are used in bitter climatic zones, for example in northern areas of the USA, in Canada, Northern China or similar areas and when, in these applications, the systems are directly exposed to the environmental effects, for example, in the case of wind power stations. The changes in viscosity of the fluid which occur at low temperatures during winter operation lead to pressure losses. Due to paraffin formation, which can take place in the fluids at low temperatures, a “freezing” of the heat exchanger can occur. In order to make fluid/air cooling systems suitable for winter, the heat exchangers concerned are conventionally designed with larger material thicknesses and/or the cooling air quantity is reduced by speed variance of the associated fan, for example using control systems of the type described in DE 10 201 056 567 A1, cited above.

With regard to these problems, the object of the invention is to provide a heat exchanging device of the type under consideration which is distinguished by improved operating performance in the lower temperature range.

According to the invention, this object is achieved by means of a heat exchanging device having the features of claim 1 in its entirety.

A significant feature of the invention is therefore that, among the collecting chambers conducting the fluid to be temperature controlled, which in each case have a fluid inlet or outlet, three or more collecting chambers are provided which are disposed parallel to one another relative to the flow direction running between the inlet and outlet. Compared with the conventional design, in which there is flow through the heat exchanger via the fluid ducts extending between the two end-side collecting chambers along the entire length, the invention, comprising at least one additional collecting chamber disposed between end-side collecting chambers, halves both the run length and the volume flow per collecting chamber. The operational pressure loss is thus reduced to a quarter of the usual value, with corresponding improvement in the operating performance at low temperatures with the associated viscosity changes. The desired winter suitability can thus be achieved without greater wall thicknesses and also with a high air throughput, so that simpler fan drives can be used and this results in overall significantly reduced production costs.

The device can advantageously be designed such that a collecting chamber with an inlet or outlet for fluid is disposed centrally between two groups of duct-like fluid guides separated from one another by means of this collecting chamber, which open at their free ends facing away from one another into an exterior collecting chamber, which has an outlet or an inlet.

The heat exchanging device can also be made up of at least two fluid/air heat exchangers which, preferably disposed in a plane, point in a common fluid flow direction with their adjacent collecting chambers and have an inlet or outlet, with the collecting chambers which are each connected via the duct-like fluid guides forming the outlet or inlet for the fluid.

In an embodiment designed in this manner, having at least two fluid/air heat exchangers, wherein one collecting chamber of a heat exchanger has an inlet and an outlet on opposite end areas, this collecting chamber can be connected in series to the inlet of the following collecting chamber of another heat exchanger.

The collecting chambers connected to one another in series can have an opposite flowthrough direction to one another when the device is in operation, wherein the additional collecting chamber of the second heat exchanger connected in series to the one heat exchanger is connected with its outlet to the inlet of the collecting chamber of the one heat exchanger, which has an outlet at its other, opposite end. This, in turn, halves the run lengths of the fluid ducts and the volume flows inside the collecting chambers. In exemplary embodiments with two or more fluid/air heat exchangers, these can be disposed in desired spatial relationships relative to one another, so that the entire device can be easily adapted to given installation situations.

For particularly good operating performance in the low temperature range, in every heat exchanger, all collecting chambers used can be selected to be the same size in terms of volume, in order to obtain the same optimal flow conditions in all collecting chambers.

Furthermore, the arrangement can advantageously be such that, across the entire construction height or construction length of a collecting chamber formed as a collecting box, the duct-like fluid guides open into same, the air flow of which during operation of the device takes place essentially transverse to the fluid guide in the connected collecting chamber.

In order to increase the air throughput for an efficient heat exchange, in particular a cooling, an assigned fan device can preferably be disposed at the front side on the duct-like fluid guides.

The invention is explained in detail below with reference to exemplary embodiments depicted in the drawings, in which:

FIG. 1 shows, as a very schematically simplified functional diagram, which illustrates only the course of the fluid flow, a heat exchanging device according to the prior art;

FIG. 2 shows, in a depiction corresponding to FIG. 1, a modified heat exchanging device according to the prior art;

FIG. 3 shows, in a schematized depiction corresponding to FIGS. 1 and 2, the heat exchanging device according to a first exemplary embodiment of the invention, and

FIGS. 4 to 7 show, in a corresponding type of depiction, heat exchangers of a heat exchanger device according to a second or third or fourth or fifth exemplary embodiment of the invention.

Of the depicted air/fluid heat exchangers in the form of plate coolers, also referred to as finned coolers, the figures show only collecting chambers with a fluid inlet and/or fluid outlet and also the fluid flow course between collecting chambers which is illustrated only with flow arrows. The structural details of the fluid guides for the fluid flow between collecting chambers as well as the details of the air guides extending transverse to the fluid guides are omitted in the simplified sketch-type figures. As an example of this type of special design of a corresponding plate bundle, with duct-like fluid and air guides extending between the plates, reference is made to the already mentioned document DE 10 2010 046 913 A1.

FIG. 1 shows a heat exchanging device 2 according to the prior art with a fluid collecting chamber 6 with a fluid inlet 8 and also with a collecting chamber 10 with a fluid outlet 12. The collecting chambers 6 and 10 have a box-like shape with a preferably rectangular cross section and are disposed on two opposite outer sides of the heat exchanger. The collecting chambers 6, 10 extend across the entire height of the plate bundle and across the dimension perpendicular to the drawing plane, so that all fluid guides 14 open into the collecting chambers 6 and 10 with the unnumbered flow arrows, with the direction of the flow running from the collecting chamber 6 having the inlet 8 to the collecting chamber 10 with the outlet 12.

FIG. 2 shows another exemplary embodiment of the prior art, wherein the fluid guides 14 again extend across the entire length of the distance between exterior collecting chambers, and wherein, by contrast with FIG. 1, the collecting chamber 6 located on the left side extends only across half the height of the bundle and another collecting chamber 16 connects to this collecting chamber 6, on which the fluid outlet 12 is provided. During operation, a flow thus occurs in this heat exchanging device 2 between the left exterior collecting chambers 6 and 16 and the opposite exterior collecting chamber 10 in a first flow direction and in a second flow direction.

FIG. 3 shows a first exemplary embodiment of a heat exchanger of the heat exchanging device 2 according to the invention. A third collecting chamber 18 is provided centrally between the collecting chambers 6 and 10 extending along opposing outer sides, which third collecting chamber extends parallel to the outer collecting chambers 6, 10. This collecting chamber 18 has the fluid inlet 8, and at each of the outer collecting chambers 6, 10 a fluid outlet 12 is provided. Inlet 8 and outlet 12 are each located on the same front side, i.e., the narrow side of the collecting chambers 6, 10, 18 which are rectangular in cross-section. This arrangement results in half the volume flow of the fluid flow entering via the inlet 8 on each side of the central collecting chamber 18 in the fluid guides 14. When the run lengths are halved the pressure loss is reduced to a quarter of the value reached with a full run length and full volume flow. This makes it possible to produce, even with thin-walled components, which permit a high level of heat exchange efficiency, a heat exchanging device which is characterized by good operating characteristics even with the viscosity ranges encountered at low temperatures. The central collecting chamber 18 disposed parallel to the exterior collecting chambers 6, 10 has the same shape and the same volume as the exterior collecting chambers 6, 10.

The second exemplary embodiment depicted in FIG. 4, corresponds to the example of FIG. 3, except that the exterior collecting chambers 6, 10 form the inlet side with one fluid inlet 8 in each case, while the central collecting chamber 18 has the fluid outlet 12. During operation, the ratios for run length, volume flow and pressure loss in the fluid guides 14 are once again the same as in the example of FIG. 3.

In the exemplary embodiments of FIGS. 5, 6 and 7, the entire heat exchanging device 2 has two central collecting chambers 20 and 22, instead of a single collecting chamber 18 disposed centrally between the exterior collecting chambers 6 and 10. As a result, the entire heat exchanging device 2 is divided into two heat exchangers 24 and 26. All collecting chambers 6, 10, 20 and 22 have the same box shape with a rectangular cross-section and have the same volume. The two exterior collecting chambers 6 and 10 each have a fluid inlet 8 as inlet sides, and the centrally located collecting chambers 2 and 22 each have a fluid outlet 12. The inlets 8 and outlets 12 are each disposed at the same front side of the collecting chambers 6, 10, 20, 22. With regards to the fluid flow, flow conditions are produced corresponding to those of the two first exemplary embodiments of FIGS. 3 and 4, i.e., the shortened run lengths with a halved volume flow in the fluid guides 14 and with the resulting advantages for winter operation.

The exemplary embodiment of FIG. 6 corresponds to the exemplary embodiment of FIG. 5, except that the central collecting chambers 20 and 22 form the inlet sides with the inlets 8, while the exterior collecting chambers 6 and 10 have the outlets 12. The division of the entire heat exchanging device 2 into the heat exchangers 24 and 26 also permits adaptation to special installation situations by means of selection of the relative positioning of the heat exchangers 24 and 26.

The exemplary embodiment of FIG. 7 corresponds to the examples of FIGS. 5 and 6 with regards to the disposition of the collecting chambers 6, 10, 20 and 22. By contrast, only the heat exchanger 24 located on the left side in FIG. 7 has a fluid inlet 8 and a fluid outlet 12. The collecting chamber 20 having the inlet 8 is connected on the front end opposite the inlet 8 to the adjacent front side end of the collecting chamber 22 of the other heat exchanger 26 via a conduit 28. In addition, the two exterior collecting chambers 6 and 10 are connected via a conduit 30 which, at the front end of the collecting chamber 6 opposite the outlet 12 opens into said collecting chamber. In this arrangement, even though the exemplary embodiment of FIG. 7 is made up of two heat exchangers 24, 26 as in the examples of FIGS. 5 and 6, it has only two external connections, namely one inlet 8 and one outlet 12. The conduits 28, 30 can be designed as pipe lines or hose lines. In all of the exemplary embodiments, pressure-actuated bypass valve devices can be disposed between inlet sides and outlet sides.

Claims

1. A heat exchanging device (2), in particular a fluid/air heat exchanger, having individual fluid-conducting collecting chambers (6, 10), which in each case have an inlet (8) or outlet (12) for fluid supply and discharge and which are connected to one another via duct-like fluid guides (14) which control the temperature of, in particular cool, a fluid flow during operation of the device by means of an air flow which flows in duct-like air guides which are separated from the fluid guides (14) in a medium-tight manner, characterized in that, to construct the entire heat exchanging device (2) at least one additional collecting chamber (18; 20, 22) is inserted between collecting chambers (6, 10) that are disposed on outer sides opposite one another, which additional collecting chamber is disposed parallel to the exterior collecting chambers (6, 10) and into which all fluid guides (14) connected to an exterior collecting chamber (6, 10) open in a similar manner.

2. The heat exchanging device according to claim 1, characterized in that one collecting chamber (18) is located centrally between two exterior collecting chambers (6, 10) connected via the fluid guides (14) and has an inlet (8) or an outlet (12) and in that the exterior collecting chambers (6,10) have an outlet (12) or an inlet (8).

3. The heat exchanging device according to claim 1 or 2, characterized in that at least two fluid/air heat exchangers (24, 26) are used which, preferably disposed in a plane, point in a common fluid flow direction with their adjacent collecting chambers (20, 22) and have an outlet (12) or an inlet (8), and in that the collecting chambers (6, 10) each connected via the duct-like fluid guides (14) form the outlet (12) or inlet (8) for the fluid.

4. The heat exchanging device according to claim 1, characterized in that at least two fluid/air heat exchangers (24, 26), preferably connected in series, are used, wherein one collecting chamber (20, 22) has an inlet (8) or outlet (12) and is connected in series via a conduit (28) to the following collecting chamber (20, 22) of another heat exchanger (24, 26).

5. The heat exchanging device according to claim 4, characterized in that the collecting chambers (20, 22) connected to one another in series have an opposite flowthrough direction to one another when the device (2) is in operation.

6. The heat exchanging device according to claim 5, characterized in that the additional collecting chamber (6, 10) of the additional heat exchanger (24, 26) connected in series to the one heat exchanger (24, 26) is connected via another conduit (30) to the collecting chamber (6, 10) of the other heat exchanger (6, 10), which has an outlet (12) on its opposite end.

7. The heat exchanging device according to claim 1, characterized in that the collecting chambers (6, 10, 18, 20, 22) having inlets (8) or outlets (12) supply, via the duct-like fluid guides (14), only one collecting chamber (6, 10, 18, 20, 22) having an outlet (12) or inlet (8).

8. The heat exchanging device according to claim 1, characterized in that the collecting chambers (6, 10, 18, 20, 22) used are selected to be the same size in terms of volume.

9. The heat exchanging device according to claim 1, characterized in that, across the entire construction height or construction length of a collecting chamber (6, 10, 28, 20, 22) formed as a collecting box, the duct-like fluid guides (14) open into same, and in that the air flow during operation of the device takes place essentially transverse to the fluid guides (14) in the connected collecting chamber (6, 10, 18, 20, 22).

10. The heat exchanging device according to claim 1, characterized in that a fan device is disposed preferably at the front side on the duct-like fluid guides (14), in order to thus increase the air throughput for an efficient heat exchange, in particular a cooling.