Packing for heat and/or mass transfer

Abstract

A packing for heat and/or mass transfer between liquid and gaseous media in counter-flow, in particular for water cooling by air in cooling towers, includes a plurality of film elements contoured by corrugations. The corrugations provide flow passages and the film elements are successively arranged behind each other in the thickness direction forming points of contact. Adjacent film elements are connected to one another at their points of contact and mutually facing large surfaces of adjacent film elements have a fine contouring. The fine contouring includes a ribbing with rib webs and rib grooves running transversely to the flow passages. A rib groove is disposed between two adjacent rib webs. The transitions between successive rib webs and rib grooves are designed such that they are substantially free of radii.

Claims

1. A packing for heat and/or mass transfer between liquid and gaseous media in counter-flow comprising a plurality of film elements contoured by corrugations, said corrugations providing flow passages and said film elements being successively arranged behind each other in the thickness direction forming points of contact, wherein adjacent film elements are connected to each other at their contact points and wherein mutually facing large surfaces of adjacent film elements have a fine contouring, wherein said fine contouring comprises a ribbing with rib webs and rib grooves running transversely to the flow passages, wherein a rib groove is arranged between two adjacent rib webs, wherein transitions between successive rib webs and rib grooves are designed in such a way that the transitions are substantially free of radii, wherein end regions of a film element which are opposite each other in the longitudinal direction are free of fine contouring, wherein channels are formed in the end regions of the film elements which are free of fine contouring and extend obliquely with respect to the longitudinal extension of the film elements, into which channels the flow passages open, wherein a film element has two channels for each flow passage, which channels are aligned to each other in a V-shape.

2. The packing according to claim 1, wherein the corrugations provide flow passages which are inclined in the longitudinal direction of the film elements, the film elements being arranged alternately in the thickness direction, so that the flow passages of adjacent film elements extend oppositely inclined and cross while forming the contact point.

3. The packing according to claim 1, wherein the transition radii are less than 20% of the rib web plateau width of the corresponding rib web.

4. The packing according to claim 1, wherein a rib groove has a groove depth of 2 mm to 3 mm.

5. The packing according to claim 1, wherein the two channels open into a common outlet that is aligned in the direction of the longitudinal extension of the film elements.

6. The packing according to claim 1, wherein the mutually facing flow passages of adjacent film elements form a film pair passage with a polygonal cross section on the input and output sides respectively.

7. The packing according to claim 1, wherein the corrugations of the film elements comprise a first strip portion extending in the longitudinal direction of said film elements as well as a second and a third strip portion disposed thereon along its respective longitudinal edges, said second and third strip portions being inclined to said first strip portion.

8. The packing according to claim 7, wherein the second and third strip portions are of equal width and each has a width that exceeds the width of the first strip portion.

9. The packing according to claim 8, wherein the width ratio of the first strip portion to the second strip portion or of the first strip portion to the third strip portion is between 0.3 and 0.4.

10. The packing according to claim 7, wherein the width of the first strip portion is at least 5 mm.

Description

DRAWINGS

(1) Further features and advantages of the invention will be become apparent from the following detailed description taken in conjunction with the drawings wherein it is shown by:

(2) FIG. 1 is a schematic side view of a cooling tower according to prior art;

(3) FIG. 2 is a schematic side view of a film element of a packing according to a first embodiment of the invention;

(4) FIG. 3 is a sectional view of the film element of FIG. 2 taken along section line B-B of FIG. 2;

(5) FIG. 4 is a front-side view of the film element of FIG. 2;

(6) FIG. 5 is a sectional view of the film element of FIG. 2 taken along section line A-A of FIG. 2;

(7) FIG. 6 is a schematic perspective view of the output side end region of the film element of FIG. 2 in extracts;

(8) FIG. 7 is a schematic perspective view of the output side end region of FIG. 6;

(9) FIG. 8 is a schematic view of a packing in accordance with the invention;

(10) FIG. 9 is a frontal view of the packing of FIG. 8;

(11) FIG. 10 is a schematic sectional view of the packing of FIG. 8 according to section line A-A of FIG. 8;

(12) FIG. 11 is a schematic perspective view of the packing according to the invention shown in FIG. 8;

(13) FIG. 12 is a schematic view of a film element of a packing according to a second embodiment of the invention; and

(14) FIG. 13 is a schematic sectional view of the film element of FIG. 12 according to section line A-A.

(15) FIG. 1 shows a cooling tower 1 as known, for example, from prior art according to WO 2009/149954 A1.

DETAILED DESCRIPTION

(16) The cooling tower 1 is equipped with a liquid cooling device, which in turn has a liquid distribution device 14 on the one hand and cooling installations 12 on the other. The liquid distribution device 14 is arranged in height direction 13 above the cooling installations 12.

(17) The liquid distribution device 14 has a plurality of distribution pipes 15 which are connected to a common feed pipe 5 on the side of the liquid. The distribution pipes 15 of the liquid distribution device 14 are equipped with nozzles 16 on the side of the cooling installations, by which nozzles the liquid supplied to the liquid distribution device 14, for example water, is distributed in the direction of the arrows 17 to the cooling installations 12 during operation.

(18) In the intended operating mode, ambient air is guided as cooling medium from bottom to top through cooling tower 1 by means of a suction fan wheel 8 in accordance with arrows 18 and 19 with reference to the drawing plane according to FIG. 1. In the course of passing the ambient air through the cooling tower 1, the air passes the cooling installations 12, which are three-layered in the embodiment shown.

(19) The liquid to be cooled by means of the cooling tower 1, for example water, is introduced into the liquid distribution device 14 via feed pipe 5. Here it reaches the distribution pipes 15, which are equipped with preferably tangentially mounted full-cone nozzles 16 for the purpose of liquid discharge. The distance between the outlet openings of the nozzles 16 and the upper edge of the cooling installations 12 determines the spraying height, which for example is 600 mm.

(20) The water distributed evenly over the cooling installations 12 by means of the liquid distribution device 14 trickles through the cooling installations 12 in counter-flow to the cooling air conveyed from bottom to top.

(21) The water cooled after trickling through the cooling installations 12 drips off from the cooling installations 12 and is collected in the water collection tank 3.

(22) As can also be seen from the illustration according to FIG. 1, support struts 6 are provided to support the liquid cooling device relative to the water collection tank 3, which support the liquid cooling device, i.e. the liquid distribution device 14, as well as the cooling installations 12.

(23) In height direction 13 above the liquid cooling device, a cooling tower jacket 2 is provided which accommodates the fan wheel 8. The fan wheel 8 is part of an axial fan 7, which also has a gear arrangement 9, a motor 10 and a shaft 11 coupling the motor 10 with the gear arrangement 9. The gear arrangement 9 together with the fan wheel 8 is supported by a column 4 that protrudes through the liquid cooling device.

(24) The cooling installations 12 provided in height direction 13 below the liquid distribution device 14 contain packings of the type according to the invention, the structure of which can be seen in the further FIGS. 2 to 13.

(25) The packing 20 in accordance with the invention (cf. FIG. 8 and FIG. 9) for heat and/or mass transfer between liquid and gaseous media in counter-flow, in particular for water-cooling by air in a cooling tower 1 according to FIG. 1, has a plurality of film elements 21 contoured by corrugations 22. Such a film element 21 according to a first embodiment is shown in a side view in FIG. 2.

(26) The corrugations 22 of the film element 21 provide flow passages 25, as can be seen in particular from the sectional view according to FIG. 3. As can be seen from this illustration, the corrugation of film element 21 is composed of successive wave crests 23 and wave troughs 24, with a wave trough 24 arranged between two wave crests and a wave crest 23 between two wave troughs 24. With reference to the drawing plane according to FIG. 3, the corrugation 22 provides flow passages 25 on both the top and bottom sides of the film element 21.

(27) As the view according to FIG. 2 shows, the flow passages 25 run in longitudinal direction 26 of the film element 21, i.e. in the intended installation case in height direction from top to bottom or from bottom to top.

(28) The preferred embodiment of the invention according to FIGS. 2 to 7 shows a film element 21 according to which the corrugations 22 provide flow passages 25 which are inclined in the longitudinal direction 26, i.e. flow passages 25 which run zigzag-shaped. This is apparent in particular from the illustration according to FIG. 2. The film elements 21 intended to form a packing 20 in accordance with the invention are arranged alternately in the thickness direction 40—also called depth direction—as shown in the illustration according to FIG. 8, so that the flow passages 25 of adjacent film elements 21 extend with opposite inclinations and cross while forming points of contact 29. At the points of contact 29, adjacent film elements 21 are connected to each other, for example by gluing and/or welding.

(29) The film elements 21 each have a fine contouring 31 on their large surfaces 30. This fine contouring 31, also called micro-corrugation or microstructure, has a ribbing 32 running transversely to the flow passages 29 with rib webs 33 and rib grooves 34, as this is apparent in particular from the side view according to FIG. 4 and the sectional view according to FIG. 5.

(30) As can be seen in particular from the sectional view according to FIG. 5, a rib groove 34 is arranged between two adjacent rib webs 33 of the ribbing 32. According to the invention, the transitions between successive rib webs 33 and rib grooves 34 are substantially free of radii. In this sense, there is a sharp-edged transition between the rib webs 33 and the rib grooves 34.

(31) In terms of the invention, a “substantially” radii-free design means a design without transition radii if possible from a manufacturing point of view. It is therefore important to avoid transition radii between the successive rib webs 33 and rib grooves 34, so that the result is a “sharp-edged” design. “Substantially” in terms of the invention means in particular that the transition radii should be as small as possible when applying conventional manufacturing processes. The more “sharp-edged” the rib design is, the more clearly the desirable effect of a turbulent flow in the intended operating conditions is achieved.

(32) As shown by FIGS. 2 and 4, for example, the end regions 35 of the film element 21 opposite each other in the longitudinal direction 26 are free of fine contouring. In particular, this ensures an improved exit of water from the packing 20 in accordance with the invention. This positive effect is supported by the fact that in the end regions 35 of the film elements 21 without fine contouring, channels 36 and 37 running obliquely to the longitudinal extension 26 of the film elements 21 are formed, as can be seen from a combined view of FIGS. 6 and 7. In this case, a film element 21 has two channels 36 and 37 for each flow passage 25, which are aligned to each other in a V-shape. These two channels 36 and 37 flow into a common outlet 38, which is aligned in the direction of the longitudinal extension 26 of the film elements 21.

(33) FIGS. 8 and 10 show a packing 20 in accordance with the invention which for the sake of clarity has only two film elements 21 arranged one behind the other in the thickness direction 40 in the example shown.

(34) When used as intended, packing 20 is supplied with air from below with respect to the drawing plane according to FIG. 8, as the arrows 27 show. The air flows into the flow passages 25 and through the packing 20 and leaves the same at the top with respect to the drawing plane according to FIG. 8. In counter-flow to this, the packing 20 is supplied with water from above with respect to the drawing plane according to FIG. 8 and corresponding to the arrows 28. The water trickles through the packing 20 from top to bottom with respect to the drawing plane according to FIG. 8 and leaves the packing 20 via the lower end region 35 with respect to the drawing plane according to FIG. 8.

(35) The flow passages 25 of the film elements 21 arranged one behind the other in thickness direction 40 complement each other to form film pair passages 39, as can be seen in particular from the sectional view according to FIG. 10.

(36) FIG. 11 clearly shows that the film elements 21 arranged one behind the other in the thickness direction 40 each provide zigzag flow passages 25, the flow passage 25 of adjacent film elements 21 extending with opposite inclination and crossing while forming the points of contact 29. The wave crests 23 and wave troughs 24 of a corrugation 22 of the contoured elements 21 are connected to each other in width direction 41, as can also be seen clearly from FIG. 11.

(37) In accordance with a second embodiment of the invention, shown in FIGS. 12 and 13, the film elements 21 are equipped with flow passages 25 running in a straight line in the longitudinal direction 26, the flow passages 25 being divided into sections which are offset from each other in the width direction 41. In contrast to the preferred embodiment according to the above FIGS. 2 to 11, no zigzag design of the flow passages 25 is provided.

(38) In accordance with the preferred embodiment according to FIGS. 2 to 11, it is also provided that the fine contouring 31 of the film elements 21 extends over the entire surface of the large surfaces 30, with the exception of the end regions 35. The alternative embodiment according to FIGS. 12 and 13 shows a fine contouring 31 that is interrupted in longitudinal direction 26 of the film element 21 by areas 42 without fine contouring. Such a design can result in particular from manufacturing reasons.

(39) The fine contouring according to the invention is in the form of a ribbing 32, as already described above in context with FIG. 5. The ribbing 32 comprises rib webs 33 and rib grooves 34 succeeding each other in the longitudinal direction 26, each of the rib webs 33 providing a rib web plateau 43. According to the invention it is provided that transitions between successive rib webs 33 and rib grooves 34 are substantially free of radii. With respect to the rib web plateau 43, i.e. with respect to the extension of the rib web plateau 43 in the longitudinal direction 26, it is preferred that the transition radii are formed <20%, preferably <10%, even more preferably <5% of the width of the rib web plateau of the corresponding rib web 33.

(40) The combination of the flow passages 25 of two adjacent film elements 21 results in a film pair passage 39, as can be seen in the sectional view according to FIG. 10 in particular. A polygonal, preferably hexagonal design of the film pair passage 39 is preferred, as shown in FIG. 10.

(41) For the design of the film pair passage 39, which is hexagonal in cross-section, a flow passage 25 defined by three strip elements 44, 45 and 46 is provided for each film element 21. The edge lengths, i.e. the widths of the strip elements 44, 45 and 46, differ from each other.

(42) The strip elements 45 and 46 have the same width, i.e. the same edge length in relation to the cross-section, and exceed the width of the first strip portion 44 or its edge length in relation to the cross-section. The edge length S1 of the first strip element 44 and the edge lengths S2 of the second strip element 45 and the third strip element 46 are illustrated as an example in FIG. 10. The width or edge ratio S1/S2 is preferably between 0.3 and 0.4, most preferably 0.35.