WO2013113362A1

WO2013113362A1 - Heat exchanger

Info

Publication number: WO2013113362A1
Application number: PCT/EP2012/051454
Authority: WO
Inventors: Marek PYZA
Original assignee: A-Heat Allied Heat Exchange Technology Ag
Priority date: 2012-01-30
Filing date: 2012-01-30
Publication date: 2013-08-08
Also published as: US20150253086A1; EP2810012A1; JP2015508881A; CN104169670A; MX2014008724A

Abstract

The invention relates to a heat exchanger (1) that comprises a housing containing a plurality of plate element arrangements (2, 12, 22) which comprise a plurality of openings (6), adjacent openings being separated from one another, and a first fluid (7) flowing through said openings when in operation. The openings extend within the plate element arrangement so as to be separated from each other in at least some sections, with adjacent plate element arrangements being spaced apart from each other such that a second fluid (8) can flow in the intermediary space (15) between two adjacent plate element arrangements (2, 12, 22). A recess (5) interrupts at least one of said plate element arrangements (2, 12, 22) such that the arrangement comprises at least one first plate element (3) and one second plate element (4), said second plate element (4) being arranged in such a manner relative to the first plate element (3) that the first fluid (7) can can first flow through the first plate element (3) and then through the second plate element (4). The recess (5) contains a flow-directing element (20).

Description

A-HEAT Allied Heat Exchange Technology AG, Euro Plaza Building G, Am Europlatz 2 / Stair 2 / 6th floor, A-1 120 Vienna, Austria

The invention relates to a heat exchanger for the exchange of heat between a refrigerant and a gas, in which it is

in particular air can act.

The use of heat exchange systems is in a barely too

survey of the number of applications known in the art. Heat exchangers are used in refrigerators, e.g. in ordinary

Household refrigerators used in air conditioners for buildings or in vehicles of all kinds, especially in automobiles, aircraft and ships, as water or oil coolers in internal combustion engines in mobile or stationary operation, as condensers or evaporators in coolant circuits. Such a heat exchanger is known for example from US 4876778. The heat exchanger is configured such that cooling water flows within tubes disposed within a plurality of plates and air flows around the plates. Cooling water and air flow into each other in cross flow. The plates provided, which are arranged parallel to each other and are separated by spacers. Such spacers may be formed, for example, as corrugated sheets.

As a result, it should be distinguished between "laminated heat exchangers" on the one hand, and "mini-channel" or "microchannel heat exchangers" on the other hand.

The well-known for a very long time laminated heat exchangers are used, as all types of heat exchangers, for the transfer of heat between two media, eg from a cooling medium to air or vice versa. The flowing inside the channels of the heat exchanger first fluid is referred to as a heat carrier in the sequence. The second flowing around the channels Fluid is referred to below as Transportfluidum. Both the

Heat transfer medium as well as the transport fluid can be in liquid or gaseous state. Water, oil, air or a refrigerant may be mentioned as examples for the heat carrier or the transport fluid. One of these media is cooled by the heat transfer accordingly, while the other medium is heated.

In general, the transport fluid, e.g. the air, a much lower heat transfer coefficient than the heat transfer medium, e.g. the coolant or heating medium that circulates within the channels of the heat exchanger. This is compensated by very different heat transfer surfaces for the two media: the medium with the high

Heat transfer coefficient flows in the channel. On the outside are thin sheets, z. B. ribs or fins attached, so that the

Outer surface of the channel has an enlarged compared with the inner surface of the channel heat transfer surface at which the

Heat transfer takes place with the Transportfluidum.

The ratio of outer surface to the inner surface of the channel depends on the lamella geometry, which in turn by the

Channel diameter, the arrangement of the channels and the distance of the channels is determined from each other, as well as the lamellar distance d 'from. Of the

Slat spacing d 'is chosen differently for different applications. However, purely thermodynamically, it should be as small as possible, but not so small that the pressure loss on the side of the transport fluid is too large. An economic optimum is about 2 mm, which is a typical value for condenser and recooler.

The efficiency is essentially determined by the fact that the heat that is transferred between the fin surface and the Transportfluidum must be transferred via heat conduction through the fins to the channel. This heat transfer is the more effective, the higher the conductivity or the thickness of the lamella, but also the smaller the distance between the channels. One speaks here of

Fin efficiency. As a lamellar material is therefore nowadays predominantly aluminum used, which has a high thermal conductivity (about 220 W / mK) to economic conditions. The distance of the channels should be as small as possible. Thermodynamic would be one

Solution, which has many channels in close proximity to each other with small diameters, optimal. A major cost factor, however, is also the working time for widening and soldering the channels. This would disproportionately increase with such a geometry.

Therefore, a few years ago, a new class of

Heat exchangers, so-called mini-channel or also

Microchannel heat exchangers have been developed that are manufactured using a completely different process, almost laminating the ideal image

Heat exchanger correspond. They contain miniature channels or microchannels with a very small diameter, which is of the order of 1 mm. For the production of these mini-channels or micro-channels aluminum extruded profiles are preferably used. Essentially, a heat exchanger block is constructed from one or more laminated heat exchangers or from one or more microchannel heat exchangers, wherein in each case one inlet side of the

Heat exchanger block with a distributor element and an outlet side of the heat exchanger block is soldered pressure-tight with a collecting element. At the distributor element and at the collecting element of the one or more

In this case, a connection connection is provided in each case for a heat exchanger block comprising heat exchangers, so that the heat exchanger block can be connected to an external system, e.g. with a chiller like that

can be connected to the flow, that the heat transfer medium in

Operating state for exchanging heat with the Transportfluidum under a predetermined operating pressure from the distributor element through the

Heat exchanger can be supplied to the collecting element.

The microchannels are arranged in plate elements. The microchannels are substantially parallel to each other and are not connected to each other, so that the heat transfer medium, so the first fluid, the plate member supplied in a microchannel, flows through the plate member in this microchannel and leaves again in the same microchannel. The transport fluid flows crosswise to the microchannels. The transport fluid gives off heat to the heat transfer medium or absorbs heat from the heat transfer medium via the walls of the plate element. Due to the cross flow therefore inlet temperature of the transport fluid differs from its outlet temperature, since on the way through the heat exchanger either heat is absorbed or released. This requires an inhomogeneous

Temperature distribution in the microchannels. In large-area heat exchangers with a heat exchange surface of several square meters, these temperature differences can

Thermal stresses and thus to mechanical loads of

Lead microchannels, which can lead to damage to the heat exchanger.

An object of the invention is therefore the temperature distribution in

Coolant in the flow direction of the gas to uniform.

The object of the invention is achieved by a heat exchanger which has the following features: The heat exchanger has a housing which contains a plurality of plate element arrangements. The

Plate element assemblies contain openings, for example in the form of tubes, which can be flowed through by a first fluid in the operating state. Microchannels may also be provided in the sense of the preceding embodiments. The openings extend within the plate element arrangement at least partially separated from each other. Adjacent plate member assemblies are each spaced apart so that a second fluid can flow in the gap between two adjacent panel member assemblies. The direction of flow of the second fluid is preferably substantially crosswise to the flow direction of the first fluid. This means that the first fluid and the second fluid preferably flow in cross-current to each other.

At least one of the plate element arrangements is interrupted by a recess, so that the plate element arrangement at least a first and comprises a second plate element. The second plate member is arranged with respect to the first plate member, that the second

Plate member of the first fluid can be flowed through after the first plate member, wherein the recess contains a current-steering element. Within the recess, there is a mixing of the individual streams of the first fluid, which reach the recess via the openings.

According to one embodiment, the recess may be configured such that a plurality of openings opens into the recess at a second end of the first plate element and the first fluid from the recess can in turn be fed into a plurality of openings at a first end of the second plate element. In particular, the recess may be configured such that a plurality of tubes, channels or microchannels opens into such a recess at a first end thereof and the first fluid from the recess in turn is fed into a plurality of tubes, channels or microchannels of the second plate member.

According to one embodiment includes recess

Stromstörelement, so that a vortex formation and / or deflection of the flow takes place. Alternatively or in addition to this, the recess may contain a static mixer. The recess can be from a

Sheath element to be surrounded, which is fluid-tightly connected to the first and the second plate member. In particular, that can

Sheath element containing the current-steering element, such as grooves and / or have ribs and / or projections. The

Recess is formed by the second end of the first plate member, the first end of the second plate member and the jacket member, wherein the first plate member and the second plate member having a common center plane and the plate members are arranged with respect to the flow direction of the first fluid in a row. In particular, the openings in the plate elements may be formed as channels. The grooves may be arranged at least in sections at an angle to the channels. The grooves may enclose with the channels an angle ranging from 10 ° to 75 ° inclusive, preferably in the range of 10 ° to 60 ° inclusive, more preferably in the range of 10 ° to 45 ° inclusive.

According to an alternative embodiment, the jacket member may include projections which protrude into the recess and

Form current baffles. Advantageously, the recess extends over between 5 and 40% of the length of the heat exchanger, the length of the

Heat exchanger in the main flow direction of within the

Plate elements flowing first fluid is measured. In order to ensure a temperature compensation over the entire width of the heat exchanger, it is advantageous if the recess extends substantially over the entire width of the heat exchanger.

A mounting element may be provided according to an embodiment for maintaining the distance between two adjacent plate elements. The mounting element may be formed in particular as a wave-shaped, thin-walled spacer element.

The invention also relates to a method for operating a heat exchanger according to one of the preceding embodiments, comprising a step in which the first fluid is arranged on its flow path within the plate element arrangement between its entry into the plate

Plate element assembly and its exit from the

Plate element assembly is mixed. According to an advantageous variant, the second fluid flows between adjacent plate element arrangements in cross flow to the first fluid. The second fluid thus flows transversely to the first fluid. The first fluid may in particular be a refrigerant. The second fluid may in particular be a gas, advantageously air. The plate members may be formed as profiles in which the refrigerant moves in a plurality of separate parallel channels. Seen in Direction of the first fluid, these channels are for the first fluid

behind each other.

The heat transfer differs from one channel to the next channel for several reasons. For one, the driving changes

On the other hand, the ratio of liquid phase to gaseous phase, when the second fluid is in the liquid and gaseous phase, which affects the overall performance of the heat exchanger.

In particular, more than one recess in one

Plate element arrangement may be provided. If a plurality of

Recesses is provided, each of the recesses can

current-steering element included. In particular, it may come to mixing of the second fluid, so that there is a temperature compensation in the second fluid and a uniformization of the temperature profile over the length and the width of the heat exchanger.

The performance of a heat exchanger can be increased considerably, in particular, if the plate element arrangements have a large width and / or length and / or the flow velocity of the first fluid is small. In particular, a heat exchanger according to the invention can be built in a greater length and the number of plate assemblies can be reduced by up to two-thirds over the prior art.

The invention will be explained with reference to the drawings. 1 shows a view of a plate element arrangement according to a first exemplary embodiment of the invention,

FIG. 2 is a view of a stack of plate element assemblies; FIG. 3 is a side view of an arrangement of plate elements,

Fig. 4 is a plan view of the arrangement of plate elements

according to FIG. 3,

6 shows a side view of an arrangement of plate elements according to a second exemplary embodiment, FIG.

Fig. 7 is a plan view of the arrangement of plate elements

according to FIG. 6,

Fig. 8 is a detail of the side view according to Fig. 6. Fig. 9 is a view of a stack of plate elements

10 is a view of a plate element arrangement according to the second embodiment of the invention.

Fig. 1 illustrates a view of a plate element assembly 2 according to a first embodiment of the invention for a

Heat exchanger 1. The plate element assembly comprises first

Plate element 3, a second plate member 4 and a recess 5, which between the first plate member 3 and the second

Plate element 4 is arranged. A first fluid 7 enters into the first plate element 3, flows through the openings 6 in the direction of the recess 5, into the recess 5 and then leaves the recess 5 through the openings 6 of the second plate element 4.

The first fluid 7 is a heat carrier and may be either a heating medium or a coolant. The first fluid 7 is preferably in liquid

State of aggregation, since its heat conduction is substantially higher than that of a gaseous fluid and the heat exchange surface available for the first fluid is smaller than for the second fluid. The openings 6 are spaced apart in the first and second plate members 3, 4 so that each of the openings 6 is one of the others Openings separate, shell side closed channel 9 is formed. The channel 9 may in particular have the shape of a tube and / or as a microchannel with the dimensions described in the introduction

be educated. The first fluid 7 flows through these microchannels, which may have wave-shaped internals, which are not shown in the drawing. These

wave-shaped internals serve to increase the for the

Heat transfer available heat exchange surface.

Of course, instead of the wave-shaped internals also lattice structures, net-like structures or porous structures can be provided. The channels 9 may be formed as circular tubes or as oval or quadrangular, in particular rectangular channels, which have been produced from an extruded profile by means of an extrusion process. This allows a variety of microchannels in the

Plate element arrangement can be arranged. As a material for the channels 9 in particular aluminum or an aluminum alloy has been proven.

The first plate member 3 has a first end 16, which is the

Includes inlet openings of the openings 6, through which the first fluid 7 is passed into the first plate member 3. The outlet openings of the

Openings 6 are arranged at a second end 17 of the first plate element 3.

The second plate element 4 has a first end 18, which contains the inlet openings of the openings 6, through which the first fluid 7 is conducted into the second plate element 4. The outlet openings of the

Openings 6 are arranged at a second end 19 of the second plate element 4.

In particular, according to FIG. 1, the recess 5 is designed such that a plurality of openings 6 at the second end 17 of the first

Plate member 3 opens into the recess 5 and the first fluid 7 of the Recess 5 in turn can be fed into a plurality of openings, which are arranged at the first end 18 of the second plate member 4.

The recess is one between the first and second

Plate element 3.4 extending cavity, which of a

Sheath element is surrounded. The recess 5 is from the second end 17 of the first plate member 3, the first end 18 of the second

Plate member 19 and the jacket member is formed, wherein the first plate member 3 and the second plate member 4 is a common

Have center plane and the plate elements 3, 4 with respect to the

Flow direction of the first fluid 7 are arranged one behind the other.

In the present illustration, the jacket element consists of an upper shell part 10 and a lower shell part 11. The upper shell part 10 is shown in the manner of an exploded view in the unassembled state, so that the structure of the lower shell part 1 1 is visible. Instead of an upper and lower shell part, the jacket element can also be formed in one piece. The first and second plate elements can be subsequently connected to the jacket element, that is, for example, inserted into openings of the jacket element for the first and second plate elements. A fluid-tight connection between the plate element is made possible by a sealing element, by a slight oversize of the plate element relative to the jacket element, or by subsequent welding of jacket element and plate element.

The upper shell part 10 and the lower shell part 1 1 have current-steering elements 20. These current-steering elements 20 are formed as ribs 21. Of course, alternatively, only one of the upper or lower shell parts may have ribs 21 and the other of the upper or lower shell parts may have a smooth surface or grooves 23. In most cases, a plurality of current-steering elements 20 is provided, in particular if the heat exchanger has a large width. However, a single current-steering element would fulfill the function of a deflection of the flow of the first fluid 7. In particular, the current-directing element 20 can at least

be arranged in sections at an angle to the channels 9.

Preferably, the current-directing element 20 encloses an angle with the channels 9 ranging from 10 ° to 75 ° inclusive,

preferably in the range of 10 ° to 60 ° inclusive, more preferably in the range of 10 ° to 45 ° inclusive.

In order to achieve an improved mixing, the current-directing elements 20 of the upper shell portion 10 may include a different angle 27 with the channels 9, as the current-steering elements 20 of the lower shell portion 1 first The angle 27 is shown in Fig. 5.

According to an alternative embodiment, the jacket element, or at least one of the upper or lower shell parts 10, 1 1 projections 25, which protrude into the recess 5 and form Stromstörelemente. The recess 5 advantageously extends over between 5% and 40% of the length 26 of the heat exchanger, the length 26 of the

Heat exchanger in the main flow direction of within the

Plate elements 3, 4 flowing first fluid 7 is measured. In Fig. 3, the length 26 of the heat exchanger as the sum of the lengths of

Plate elements and the recess 5 shown.

In particular, the recess 5 may extend substantially over the entire width 28 of the heat exchanger 1. The width 28 of the heat exchanger 1 substantially corresponds to the width of

Plate element assembly and is shown in Fig. 5. FIG. 2 shows a stack of plate element arrangements 2, 12, 22, which form a heat exchanger 1. These plate element assemblies 2, 12, 22 are located in a housing, which is omitted in the illustration in order to better illustrate the operation of the heat exchanger can. Each of the plate element assemblies 2, 12, 22 can be made of the in Fig. 1 and the first and second plate elements 3, 4 and one shown

Recess 5 be constructed.

A second fluid 8, also referred to as transport fluid, may flow above and / or below each plate element assembly 2, 12, 22. The second fluid 8, which is usually gaseous, can be heated by means of the heating means or cooled by means of the coolant, depending on the desired mode of operation of the heat exchanger 1.

The gap 15, which is traversed by the second fluid 8, may include mounting elements 13, which are shown in Fig. 2 as a corrugated structure. The mounting elements 13 are connected to the respective adjacent

Plate element assemblies in thermally conductive contact, so that heat can be transmitted through the mounting elements 13. Thus, the mounting elements 13 serve to increase the heat exchange surface. The

Built-in elements may also be formed as ribs or as above lattice structures, net-like structures or contain porous structures. Furthermore, the mounting elements can also be designed as serrated profiles in V or W shape.

Fig. 3 shows a side view of a plate element assembly according to the first embodiment. The thickness of the shell element, consisting of upper and lower shell part 10, 1 1 exceeds the thickness of the first and second plate elements 3, 4. This has the consequence that the distance between adjacent plate element assemblies is lower at the point at which the shell element located. According to the variant illustrated in FIG. 10, installation elements 29 are therefore provided between the jacket elements of adjacent plate element arrangements, which elements have a smaller height than the installation elements 13.

FIG. 4 shows a top view of the arrangement of plate elements according to FIG. 3. This view corresponds to the arrangement of FIG. 1 when the upper casing part 10 is removed. The length of the plate element arrangement 2 is defined here as the length of the first and second plate elements 3, 4 and the length of the recess 5, which is not visible here. . FIG. 5 is a detail of the plan view according to FIG. 4 and shows a part of the lower jacket element 11 and the ribs 21 which form the current-directing element 20. The width 28 of the plate element assembly is also shown. Fig. 6 shows a side view of a plate element arrangement according to a second embodiment of the invention. This plate element arrangement differs in the construction of the first and second plate elements 3, 4, which instead of channels have a porous structure through which the first fluid 7 can flow. The recess contains as current-directing elements a plurality of projections 25, which

Can form interference elements 24 for the flow. These projections may be local elevations, or may be ribs or grooves extending over a portion of the length and / or width of the recess.

7 is a plan view of the arrangement of plate elements according to FIG. 6 and is constructed analogously to FIG. 3, therefore, see the description of FIG. 3.

FIG. 8 shows a detail of the side view according to FIG. 6. The current-directing elements 20 are designed as ribs. The ribs of the upper shell part and the lower shell part come to rest in the installed state. The first fluid can thus flow past only these ribs and is deflected by the ribs and by the deflection and / or

Turbulence mixed. As a result, the temperature gradient, which has the first fluid in the width direction of the heat exchanger,

balanced.

Fig. 9 shows a view of a stack of plate elements, similar to Fig. 2. In contrast to Fig. 2, the mounting elements 29 between the

Sheath elements of the recesses 5 are shown, which differ in their height from the mounting elements 13, which between the

Plate elements 3, 4 are arranged. Fig. 10 shows a view of a plate element arrangement according to the second embodiment of the invention. The upper and lower shell parts 10, 11 are shown as a transparent element, so that the projections, which extend across a part of the inner surface of at least one of the shell parts in the form of pairs of ribs, are visible.

Claims

claims

1 . A heat exchanger (1) comprising a housing containing a plurality of plate element assemblies (2, 12, 22), wherein the

Plate element assemblies include a plurality of openings (6), wherein adjacent openings are separated from each other, wherein the

Openings in the operating state of a first fluid (7) are flowed through, wherein the openings within the plate element arrangement extend at least partially separated from each other, wherein

adjacent plate element assemblies each at a distance

are arranged to each other, so that a second fluid (8) in the

Gap (15) between two adjacent plate element arrangements (2, 12, 22), characterized in that at least one of the plate element arrangements (2, 12, 22) is interrupted by a recess (5), so that the plate element arrangement at least a first plate element ( 3) and a second plate member (4), wherein the second plate member (4) is disposed with respect to the first plate member (3) such that the second plate member (4) from the first fluid (7) is adjacent to the first plate member (3) through which the recess (5) contains a current-directing element (20).

2. Heat exchanger according to claim 1, wherein the recess (5) is configured such that a plurality of openings (6) at a second end (17) of the first plate member (3) opens into the recess (5) and the first fluid ( 7) from the recess (5) in turn in a plurality of openings (6) at a first end (18) of the second plate member (4) can be fed.

3. Heat exchanger according to claim 1 or claim 2, wherein the recess contains a Stromstörelement and / or a static mixer.

4. Heat exchanger according to one of the preceding claims, wherein the recess is surrounded by a jacket element which is fluid-tightly connected to the first and the second plate member.

5. Heat exchanger according to claim 4, wherein the jacket element the

current-conducting element (20) which may be configured as a rib (21) and / or groove (23) and / or projection (25).

6. Heat exchanger according to one of the preceding claims, wherein the recess (5) of the second end (17) of the first plate member (3), the first end (18) of the second plate member (4) and the

Sheath element (10, 1 1) is formed, wherein the first plate member (3) and the second plate member (4) have a common center plane and the plate members with respect to the flow direction of the first fluid (7) are arranged one behind the other.

7. Heat exchanger according to one of the preceding claims, wherein the openings (6) in the plate elements (3, 4) as channels (9) are formed.

8. Heat exchanger according to claim 7, wherein the current-directing element (20) at least in sections at an angle (27) to the channels (9) is arranged.

9. Heat exchanger according to claim 7 or 8, wherein the current-steering

Element (20) with the channels (9) includes an angle (27), which in

Range of 10 ° to and including 75 °, preferably in the range of 10 ° to 60 ° inclusive, more preferably in the range of 10 ° to

including 45 °.

10. Heat exchanger according to claim 4, wherein the jacket element contains projections which protrude into the recess and form Stromstörelemente.

1 1. Heat exchanger according to one of the preceding claims, wherein the recess over between 5% and 40% of the length (26) of the

Heat exchanger extends, wherein the length (26) of the heat exchanger in the Main flow direction of the flowing within the plate members first fluid (7) is measured.

12. Heat exchanger according to one of the preceding claims, wherein the recess (5) extends substantially over the entire width (28) of the heat exchanger.

13. Heat exchanger according to one of the preceding claims, wherein a mounting element (13) for keeping the distance between two adjacent plate element assemblies (2, 12, 22) is provided.

A method of operating a heat exchanger (1) according to any one of the preceding claims, comprising a step of placing the first fluid (7) on its flow path within the plate element assembly (2, 12, 22) between its entry into and exit from the plate element assembly is mixed from the plate element assembly.

The method of claim 14, wherein the second fluid (8) flowing between adjacent plate element assemblies flows in cross-flow to the first fluid (7).