WO2014096609A1 - Plate for a heat exchanger - Google Patents

Abstract

The invention concerns a plate (10, 20) for a heat exchanger intended for exchanging heat between a first fluid flowing in contact with a first face (F1) of the plate (10, 20) and a second fluid flowing in contact with a second face (F2) of the plate (10, 20), said plate (10, 20) comprising a set of corrugations forming cavities (36) extending between a bottom (33) of a hollow and an opening (32) defined between two consecutive peaks (34) of the set of corrugations, the bottom (33) and the opening (32) being separated by a distance matching the height (H) of the corrugation. The plate of the invention is such that the width of the cavities (36) varies from one side of the exchanger to the other, from a high pressure area to a low pressure area, so as to equalise the speed profiles of the first and second fluids.

Description

 Plate for heat exchanger

The present invention relates to the field of aerodynamics and particularly relates to a plate for a heat exchanger for the exchange of heat between two fluids having a low thermal conductivity, typically gases.

 It is known to provide a heat exchanger comprising a plurality of plates superimposed in a stack whose plate spacing is low so as to obtain a laminar flow.

 Said plate extends substantially in a general plane revealing a first plate face and a second plate face opposite to the first plate face, said plate comprising a so-called core zone intended for the flow of a first fluid on the plate. first face of the plate in a first direction, and for the flow of a second fluid on the second face of the plate in a second direction opposite to the first direction.

 The core zone is the location where heat exchange is optimized.

 In particular, the core zone comprises a set of reliefs having the form of corrugations increasing the specific surface of the plate.

 This type of plate is satisfactory in that it allows for efficient heat exchange, despite the laminar nature of the flows.

 However, the core zone generates high pressure losses by viscous friction on the walls of the corrugations.

 Furthermore, over the width of the heat exchanger or a plate of the heat exchanger, the velocity profile may be irregular from one edge to the other of the heat exchanger, resulting in a different flow rate between the different channels. .

 In particular, the speed is lower in the channels arranged opposite the areas of higher pressure output.

To remedy this drawback, the present invention relates to a plate for a heat exchanger for heat exchange, a first fluid flowing in contact with a first face of the plate and a second fluid flowing at contact of a second face of the plate, said plate comprising a set of corrugations forming a first set of open channels on the first face of the plate and a second set of open channels on the second face of the plate, the channels of the first and second sets being arranged alternately and separated by a plate wall. According to the invention, the width of the open channels on the first face of the plate of the first set of channels varies transversely from a first side of the plate to a second side of the plate, the width of the open channels on the second face of the plate of the second set of channels varies transversely from a first side of the plate to a second side of the plate.

 According to one aspect of the invention, the direction of variation of the width of the channels of the first set is the same as the direction of variation of the width of the channels of the second set from a first side to a second side of the board.

 According to an additional characteristic, the width of a channel of the first set open on a first face of the plate and the width of an adjacent channel of the second set of channels open on the second face of the plate are equal.

 According to an additional feature, the channel width variation of each set is performed in adjacent groups of channels.

 According to an additional characteristic, the variation of the width of the channels of each set is carried out gradually over the width of the plate.

 According to a further feature, the plate comprises a zone for outputting the fluid, downstream of a portion comprising the set of corrugations, and a wall for guiding the flow delimiting the exit zone inclined with respect to the direction. channels of the set of ripples. The channels of the set of corrugations having the greatest width are arranged on the side of the heat exchanger closest to the guide wall of the outlet zone.

According to an additional feature, the plate comprises a fluid inlet zone, upstream of a portion comprising the set of corrugations, and a flux guide wall delimiting the entry zone inclined with respect to the direction. channels of the set of ripples. The channels of the set of corrugations having the smallest width are arranged on the heat exchanger side closest to the guide wall of the inlet zone. The present invention also relates to a heat exchanger comprising a set of pl aq ues such as q ue described above superimposed in a stack. Said assembly comprises an elementary plate of the first type and a second type of elementary plate different from that of the first type, the plate of the first type being alternated with a plate of the second type in the stack of plates so that the vertices of the The corrugations of the plate of the first type are opposite the cavities of the corrugations of the plate of the second type in the stack of plates. The width variation of the channels of the first plate facing the channels of the second plate is made in the same direction transversely so that channels of the same width are arranged opposite at any point of the width of the plates.

 This arrangement makes it possible to ensure a homogeneous distribution of the fluid between the cavities of the plate of the first type and the cavities opposite the plate of the second type, at any point along the width of the plates, so as to improve the heat exchange at the through walls of the plate.

 Other features and advantages of the present invention will be better understood from the description and the appended drawings in which:

- Figure 1 shows a perspective view of an exchanger according to the invention;

 Figure 2 shows a schematic top view of a plate of the exchanger of Figure 1;

 Figure 3 is a perspective view of a plate of the exchanger of Figure 1;

 Figure 4 shows a schematic top view of a plate of the exchanger to explain the technical problem underlying the invention; Figure 5 shows a cross section of a portion of a pair of adjacent plates in one embodiment;

- Figure 6 shows a cross section of a pair of adjacent plates throughout its extension.

 As illustrated in FIGS. 1 to 6, a heat exchanger 1 comprises a plurality of plates 10, 20 superimposed in a stack 2.

Each plate 10, 20 extends along a general plane P. In the embodiment shown, the stack 2 is obtained by alternating a plate of a first type with a plate of a second type whose specificities are described later in the text.

 In the embodiment shown, each plate 10, 20 is in the form of a hexagon whose sides form an outer contour 3.

 In the same way, the end plate 10, 20 is supported or supports another plate 10, 20 of different type by means of contoured edges 4 distributed over the contour 3 of FIG. the plate 10, 20.

 As illustrated in FIG. 2, each plate 10 comprises an inner zone 30 otherwise called core zone 30 intended for the flow of a first fluid F1 on a second face F2 of the plate 10 and intended for flow. a second fluid fl2 on a first face F1 of the plate, 10.

 Each plate 20 also includes an inner zone 30, otherwise known as a core zone 30 intended for the flow of a first fluid F1 on a first face F1 of the plate 20, and intended for the flow of a second fluid F1. on a second face F2 of the plate 20.

 Generally, in order to promote the exchange of heat in a heat exchanger 1, the first fluid fl1 flows in the core zone 30 in a first flow direction S1 and the second fluid fl2 flows in the core zone 30. in a second flow direction S2 opposite to the first flow direction S1.

 In the remainder of the description, it will be considered that the direction of flow of the first fluid fl 1 is opposite to the direction of flow of the second fluid fl2.

 These flows are laminar in the core zone 30 of the heat exchanger 1, which is usually induced by low flow rates.

 In the example shown, the core area 30 comprises an assembly 6 of uniform corrugations 35 forming cavities or channels 36 for the flow of fluid F1, F1.

These corrugations 35 are centered on the general plane P of the plate 10, 20. The set of corrugations 35 is formed by the cavities 36 which extend between a bottom 33 of a hollow and an opening 32 joining two consecutive peaks 34 of the set of corrugations 35.

 The opening 32 of the cavity 36 is alternately disposed facing the first face F 1 or is the second face F 2 between two adjacent corrugations.

 The bottom 33 and the aperture 32 are separated from a line corresponding to the height H of the corrugation 35. The ratio between the height H and the width at mid-height of a cavity 36 defining the slenderness of the cavity 36 or the corrugation 35 may for example be greater than or equal to three. The function of a ripple 35 having such slenderness is described later in the text.

 In addition, each plate 10, 20 also comprises a first inlet / outlet zone 41 intended to guide in a third flow direction S3, the first fluid fl1 from the outside of the plate to the core zone 30. , and to guide in a fourth flow direction S4, the second fluid fl2 from the core zone 30 to the outside of the plate 10, 20.

 Each plate 10, 20 also comprises a second input / output zone 42 intended to guide the first fluid fl1 from the core zone 30 to the outside of the plate 10 in the direction of the third flow direction S3. , and to guide in the fourth flow direction S4, the second fluid fl2 from outside the plate 10, 20 to the core zone 30.

 As illustrated in the representation shown in FIG. 2, the directions taken by the third direction of flow and the fourth direction of flow S4 intersect in two directions forming an angle a corresponding to the value of the angle between the two. sides of the inlet / outlet zone 41, 42 of the exchanger.

 More generally, the directions taken by the third direction of flow S3 and the fourth direction of flow S4 intersect in two directions forming an angle corresponding to the angle between two adjacent sides of a polygon conferring on a plate 10, 20 its general form.

 In order to maintain a small amount of noise in the input / output areas 41, 42 in the space formed between each plate 10, 20 of the stack 2, two elementary plates 10, 20 are therefore necessary:

a first elementary plate 10 or first type whose input / output zones 41, 42 cause a laminar flow according to the direction of the third flow direction S3 on the first face F1 and a laminar flow in the direction of the fourth flow direction S4 on the second face F2, and

 a second elementary plate 20 or of a second type whose input / output zones 41, 42 cause a laminar flow in the direction of the fourth flow direction S4 on the first face F1 and a laminar flow in the direction of the third direction flow S3 on the second face F2.

 In addition, the set 6 of the corrugations 35 of the core area 30 of the first type plate 1 0 and the set 6 of the corrugations 35 of the core area 30 of the second type plate 20 are in phase, the vertices 34 of the corrugations 35 of a plate of the first type 10 being aligned with the vertices 34 of the corrugations 35 of a plate of the second type 20.

 Thus, during the superposition of a plate of the first type 1 0 and a plate of the second type 20 to form the stack 2 of plates 10, 20, the peaks 34 of the corrugations 35 of the core zone 30 of the first type plate 10 respectively of the second type plate 20, are vis-à-vis with the cavities 36 of the corrugations 35 of the core zone 30 of the adjacent plate of the second type 20 respectively of the adjacent plate of first type10 through openings 32 of cavities 36.

 In order to stiffen the stack 2 of plates 1 0, 20, each input / output area 41, 42 comprises a second set 7 of patterns 45 formed by a set of rel iefs otherwise called guides 43 and bases 44, the guides 43 being arranged facing the face F1 of a plate 10,20 and the bases 44 being arranged facing the face F2 of a plate 10,20.

 The positioning of the guards 43 and the bases 44 is performed in such a way that the guides 43 of a plate 10, 20 adjacent in the stack 2 rest or create points of support on or for the bases 44. of the plate 10, 20 considered, thereby reinforcing the cohesion of the stack 2 of plates 10, 20.

 In addition, the height of these guides 43 also allows the support of the edges of the plate 10, 20 on the edges of a plate 1 0, 20 adjacent to achieve sealing of the heat exchanger 1.

The superposition of two plates 1 0, 20 in the stack 2 creates a duct 5 for a first fluid fl1 between two adjacent plates 10, 20. The first fluid fl1 passes through the conduit 5 by first entering a space between two input / output areas 41, 42.

 The first fluid F1 then takes the form of a fluid blade with a substantially horizontal orientation given by the general orientation of the plates 10, 20.

 The fluid fl 1 then reaches a space between two core areas 30 of two adjacent plates 10, 20 in which it is distributed in different channels formed by the cavities 36 of the core areas 30 of the two adjacent plates 10, 20. L The general orientation of the fluid web penetrating into the heat exchanger then reverses to change from a substantially horizontal orientation to a substantially vertical orientation in the core zone 30 thereby increasing the space between the plates. on the input / output areas 41, 42 and to concentrate the pressure drops on the core area.

 Due to the superposition of two adjacent corrugated plates, each channel of one of the two plates 10, 20 is in communication with two channels of the other plate 10, 20.

 However, the gap separating the apex 34 from the corrugation 35 of a plate of the first type 1 0 and the two bottoms 33 of the two consecutive corrugations of the second plate 20 superimposed on the first plate 10 in the stack 2 of plates is minimized so as to increase the pressure losses in this zone.

 This increase in pressure drop substantially reduces the fluid passages from a cavity 36 of the core zone of the first plate 10 to a cavity 36 of the core zone of the second plate 20 and vice versa.

 Finally, at the outlet of the core zones 30, the first fluid F1 finds a substantially horizontal general orientation. Similarly, the second fluid fl2 passes in the same way another duct 5 formed by the addition of a plate 10, 20 to the two previous plates in the stack 2.

 In Figure 4, there is shown a schematic top view of a plate of the exchanger to explain the technical problem underlying the invention.

The elements already described are not described further. However, as illustrated in FIG. 4, as one moves along the direction H, on the input-output zone 42 there is a pressure zone On the other hand, a low pressure zone ZPF, the pressures lying between these two zones and this for a direction of fluid flow from the heart zone to the outside. Other distributions of zones of different pressures can meet.

 When the fl uid e e n t o n th e ang er ized in accordance with the orientation H shown in Figure 4, differences in the output speed of fluids fl1 or fl2 of the order of 30% can be observed from one side to the other of the exchanger. When the fluid entering the exchanger circulates in the orientation V shown in Figure 4, differences of the order of 4% can be observed.

 According to the invention, it has been discovered that this arrangement of the pressures limits the quality of the exchanger. A solution has been developed in which the widths of the cavities or channels 36 traversed by the vertical laminar flows of either fl1 or fl2 fluid vary transversely from one side of the plate to a second side of the plate. In one embodiment, the widest channels on a given plate of the exchanger are positioned opposite the zone of high pressures ZPF encountered by the fluid fl1 or fl2 when it leaves the core zone 30 and arrives in the input-output zone 41, 42. The narrowest channels are arranged vis-à-vis the zone of the low pressures ZPf encountered by the fluid fl 1 or fl2 when it leaves the core zone 30 and arrives in the input-output zone 41, 42.

 Figure 5 shows a cross section of a portion of a pair of adjacent plates in one embodiment. Note that on a stack of two plates, the first type plate 10 has input-output areas 41, 42 for a first fluid fl1, while the second type plate 20 has input-output areas 41 , 42 for a second fluid fl2 (see in particular Figures 3 and 4).

 As can be seen in FIG. 5, a first type plate 10 defines with a plate of the second type 20 disposed below the plate of the first type 10, a passage section in which the first fluid fl1 flows in the direction R between the input-output areas 41 and 42 of the first-type plate 10.

The passage section is defined, because of the nesting of the first type 10 and second type plates 20, by the channels or cavities 36 of the first type plate 1 0 which are in communication with the channels of the first type and other of the channel 36 of the second type plate 20, arranged immediately below the drawing. As a result, the channel 36 formed under the top 34 of the corrugation of the second type plate 20 immediately below the channel 36 formed under the top 34 of the corrugation of the first type plate 10 must have a width L2 equal to the width L2 of the cavity 36 of the first type plate 1 0 vis-a-vis. These open channels of width L1 on the top of the plate of first type 10 are traversed by the second fluid fl2 in the direction marked A in FIG. 5, when the plate of first type 10 is surmounted (not represented) by a plate of second type 20. The situation is repeated on the entire stack of the exchanger.

 It is noted that the widths L1 and L2 are measured on the median plane (P) of each plate at mid-height H / 2 of each undulation.

 Figure 6 shows a cross section of a pair of adjacent plates throughout its extension. Note in Figure 6 that the corrugations of each plate of first or second type can, for each plate, be classified into two categories:

 a first set of channels opened by the corrugations on the first face of each plate; and

 a second set of open channels between the same undulations on the second face of each plate;

each set of channels thus forming respectively downwardly open first type channels of Figure 6 and upwardly open second type channels of Figure 6, a first type channel being adjacent to a second type channel of each side of the same plate. The core areas of the first and second types of plate plates are divided into three groups from left to right:

 a part P1 in which the channels of first and second types are of the same width L1 = L2, and this identically for the two plates of first type 10 and second type 20; and

a part P2 in which the channels of first and second types are of the same width L1 '= L2' with L2 '> L2; and

 a part P3 in which the channels of first and second types are of the same width L1 "= L2" with L2 "> L2 '.

In other embodiments, several groups of varying widths from left to right in FIG. 6 are provided. In each group of channels considered, the widths L1, L2 are constant. In other embodiments, the width variation of L1 and L2 is gradual all along the transverse to the corrugations, in the plane (P) at half height (H / 2) of the corrugations 35.

 It will be noted that the largest cavity or channel widths of a plate 10, respectively 20, in register with the cavity 36 under the top 34 of the corrugations of a plate 20, respectively 1 0, are arranged on the side of the ZPF strong pressure zones relative to the input-type areas 41, 42. A first guide wall 50 of the flow delimits the exit zone inclined relative to the direction of the channels, the channels having the largest width being arranged side of the exchanger closest to the first guide wall 50 of the exit zone.

 Conversely, a second guide wall 51 of the flow defines the entry zone inclined with respect to the direction of the channels, the channels having the smallest width being disposed on the side of the exchanger closest to the second guide wall 51 from the entrance area.

 In an exemplary embodiment, the width variation of the channels from one edge to the other of the plate is 10 hundredths of a millimeter by producing series of 13 channels around an average channel width value of 1.35. millimeter.

 Using such an arrangement of the corrugations and channels, an equalization of the fluid output velocities fl 1, fl 2 has been measured in a cross section (P 0) of the input-output area 41.

 In one embodiment, the ratio between the height H of the corrugations 35 and L1 is at least 3.

 In one embodiment, the first and second type plates are made of amorphous polyethylene terephthalate.

It will be understood that the various embodiments described above are only examples of implementations of the invention as defined by the appended claims. Variations of these various embodiments can be envisaged and the various embodiments described can be easily combined by those skilled in the art.

Claims

 1. Plate (10, 20) for a heat exchanger (1) for exchanging heat between a first fluid (fl 1) flowing in contact with a first face (F1, F2) of the plate (20, respectively 10) and a second fluid (fl2) flowing in contact with a second face (F1, F2) of the plate (1 0, respectively 20), said plate (1 0, 20) comprising an assembly (6 ) of corrugations (35) forming a first set of open channels on the first face of the plate and a second set of open channels on the second face of the plate,  the channels of the first and second set being arranged alternately and separated by a plate wall,  characterized in that  the width of the open channels on the first face of the plate of the first set of channels varies transversely from one side of the plate to a second side of the plate,  the width of the open channels on the second face of the plate of the second set of channels varies transversely from a first side of the plate to a second side of the plate.  A plate according to claim 1, wherein the direction of variation of the width of the channels of the first set is the same as the direction of variation of the width of the channels of the second set from a first side to a second side of the plate. .  3. Plate according to one of claims 1 and 2, wherein the width (L1) of a channel of the first set open on a first face of the plate and the width (L2) of an adjacent channel of the second set of open channels on the second face of the plate are equal.  4. Plate according to one of claims 1 to 3, wherein the variation of the width of the channels of each set is performed by adjacent groups of channels (P1, P2, P3). 5. Plate according to one of claims 1 to 3, wherein the variation of channel width of each set is performed gradually over the width of the plate. 6. Plate, according to one of the preceding claims, comprising: a fluid outlet zone downstream of a part comprising the set (6) of corrugations (35), and a guide wall (50) of the flow delimiting the exit zone inclined with respect to the direction of the channels of the set (6) of corrugations (35), the channels of the set of corrugations having the greatest Width being positioned on the side of the exchanger the closest to the guide wall (50) of the exit zone.  Plate according to one of the preceding claims, comprising:  an inlet zone of fluid upstream of a portion comprising the assembly (6) of corrugations (35), and  a flow guide wall (51) delimiting the entry zone inclined with respect to the direction of the channels of the corrugation unit (6) (35), the channels of the corrugation unit (35); having the smallest width being arranged on the heat exchanger side closest to the guide wall of the inlet zone.  Heat exchanger (1) comprising a set of plates (1 0, 20), according to one of the preceding claims, superimposed in a stack (2), said assembly comprises a basic plate of the first type (10) and an elementary plate of second type (20) different from that of the first type (10), the first type plate (10) being alternated with a plate of the second type (20) in the stack (2) of plates (10, 20) so the vertices (34) of the corrugations (35) of the first-type plate (10) are arranged opposite the cavities (36) of the undulations (35) of the second-type plate (20) in the stack ( 2) of plates (10, 20), the change in width of the channels of the first plate facing the channels of the second plate is made in the same direction transversely so that channels of the same width are arranged opposite in any point of the width of the plates.