FIELD OF THE INVENTION
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The invention relates to a heat exchanger, in particular the heat exchanger for a motor vehicle.
BACKGROUND OF THE INVENTION
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To reduce the impact on climate change and under international pressure to reduce the CO2 emissions for vehicle refrigerants used in mobile HVAC and refrigerant systems, the new refrigerant such as R744 (carbon dioxide or CO2) has been introduced.
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Thermodynamically, the R1234yf refrigerant has similar properties to R134a. However, its global warming potential or GWP is only 4, as opposed to 1430. The refrigerant R744 has been assigned a GWP value of 1 and functions as the reference gas.
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Systems designed for use with R744 must withstand significantly higher pressures than those intended for R1234yf. This makes controlling the system more difficult, but not problematic. The coefficient of performance or COP is the same in moderate climate conditions, but slightly poorer in hot, moist climate zones. The system can be designed to compensate for this, as the components are smaller because of the higher volumetric cooling capacity of R744.
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In comparison to R134a and R1234yf systems, the R744 refrigerant is at a disadvantage as R744 absorbs slightly less energy per unit of flow in a refrigerant cycle. In order to increase the performance level to that of R134a or R1234yf it is advised to use an Internal Heat exchanger (IHX).
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An Internal Heat exchanger (IHX) is used to transfer heat between the low side pressure and the high pressure flow circuits. Its function is to improve system performance by further cooling the refrigerant being supplied to, for example, an evaporator through the refrigerant control device.
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Commonly used internal heat exchangers usually comprise, for example, a coaxial tube heat exchanger and a stacked heat exchanger.
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The coaxial heat exchanger is usually designed as a "tube in tube" structure. Usually such heat exchange is fully made of aluminum. Other materials can also be used depending on the requirements of working conditions. The coaxial heat exchanger usually conveys two fluids through separate circuits, wherein one circuit is conveyed in the opposite direction with respect to the other fluid.
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The stacked plate heat exchanger design is usually suited to transferring heat between medium- and low-pressure fluids. Welded, semi-welded and brazed heat exchangers are used for heat exchange between high-pressure fluids or where a more compact product is required. In place of a pipe passing through a chamber, there are instead two alternating chambers, usually thin in depth, separated at their largest surface by a corrugated metal plate. The plates used in a plate and frame heat exchanger are obtained by one piece pressing of metal plates. Stainless steel is a commonly used metal for the plates because of its ability to withstand high temperatures, its strength, and its corrosion resistance.
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Due to its structure, both coaxial and plate heat exchangers are usually not suitable for high-pressure R744 refrigerant. In spite of enhancing their structure and improving the sealing they are still prone to leakage when the high-pressure fluid is introduced. Further, the efficiency conventional heat exchangers can be increased mainly by scarifying it compactness. In other words, it is difficult to increase the efficiency of the conventional heat exchanger without an impact to its packaging. Consequently, the heat exchangers described above are inconvenient in terms of packaging, costs of production and weight reduction.
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It would be desired to produce an internal heat exchanger that would sustain the pressure of high-pressure fluids, such as R744. The sub-components should preferably be made of inexpensive materials while maintaining high quality of the final product. Further, the production process of sub-components should be simple and efficient i.e. it would be desired to manufacture each sub-component using a method that does not require complicated production process.
SUMMARY OF THE INVENTION
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The object of the invention is, among others, a heat exchanger for a heat exchange between a first fluid and a second fluid, the heat exchanger comprising: a plurality of first plates stacked together in a first stacking direction, wherein the first plates comprise a first wall forming circumference of each of the first plates, wherein the first walls of consecutive first plates are in contact with each-other, a plurality of corrugated plates, wherein at least one of the corrugated plates is sandwiched between neighboring first plates, wherein the first plates together with corrugated plates form a first pair of manifolds for the first fluid, and a second pair of manifolds for the second fluid, wherein the first pair of manifolds is fluidly connected by a first passage, and the second pair of manifolds is fluidly connected by a second passage, wherein in that the first plate comprises a substantially planar portion extending in a first direction, wherein the planar portion is surrounded by the first wall so that the first wall protrudes directly form the planar portion in a second direction being different than the first direction.
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Advantageously, the plurality of first plates along with the plurality of corrugated plates form at least one first passage for the first fluid and at least one second passage for the second fluid.
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Advantageously, the corrugated plate is in contact with at least one planar portion.
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Advantageously, the corrugated plate (200) is separated from the first wall by a non-null gap.
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Advantageously, the corrugated plate comprises at least one collar surrounding at least one of the second pair of manifolds or the first pair of manifolds. Advantageously, the collar comprises a first portion and a second portion, wherein the first portion at least partially delimits the manifold, and the second potion at least partially delimits the passage, wherein the first portion is connected directly to the second potion.
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Advantageously, the first portion and the second potion are unitary with the corrugated plate.
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Advantageously, the first portion, the second potion of the corrugated plate and the planar portion of the first plate together form a first zone wherein the first zone is fluidly insulated from any of the first or second fluid.
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Advantageously, the corrugated plate comprises a first flat section, wherein the first flat section protrudes directly from the first portion.
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Advantageously, the corrugated plate comprises a second flat section, wherein the second flat section protrudes directly from the second section.
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Advantageously, the number of collars associated with the any of the manifolds is half the number of the corrugated plates present in the heat exchanger.
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Advantageously, all corrugated plates are identical, wherein every second corrugated plate is rotated relative to the adjacent corrugated plate by 180 degrees, while the axis of rotation is determined parallel to the first stacking direction.
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Advantageously, the plurality of flat plates and the plurality of the corrugated plates are interposed between a first end plate and a second end plate.
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Advantageously, any of the first end plate (301) or the second end plate comprises at least one block, wherein said end plates are configured to provide a fluidal communication between the block and respective manifold.
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Advantageously, the heat exchanger is configured to work as internal heat exchanger.
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The invention described above allows providing the heat exchanger which is compact, inexpensive and provides excellent robustness, In particular when the heat exchanger allows heat exchange between two fluids circulating at a very high pressure.
BRIEF DESCRITPTION OF DRAWINGS
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Examples of the invention will be apparent from and described in detail with reference to the accompanying drawings, in which:
- Fig.1 shows a perspective view of the heat exchanger.
- Fig. 2 shows a perspective view of a standalone first plate.
- Fig. 3 shows a perspective view of the standalone corrugated plate.
- Fig. 4 shows a perspective view of the stack of the first plated and corrugated plates, wherein the corrugated plate is on top of the stack.
- Fig. 5 shows a cross-sectional view of the heat exchanger with a detailed section.
DETAILED DESCRIPTION OF THE INVENTION
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The subject- matter of the invention relates to a heat exchanger for a motor vehicle. The motor vehicle may be regarded as a vehicle powered by conventional fuels, i.e. it comprises an internal combustion engine, as well as hybrid vehicles and electric vehicles.
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The heat exchanger may be in particular an internal heat exchanger (IHX) or any other plate-type heat exchanger.
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A heat exchanger 1 may be configured for a heat exchange between a first fluid and a second fluid. The exemplary heat exchanger 1 working as the IHX is shown in Fig. 1, where R1in and R1out designates the inlet and the outlet for the first fluid, being the refrigerant having first parameters, whereas R2in and R2out designates the inlet and the outlet for the second fluid, being the refrigerant having second parameters. R1in, R1out, R2in and R2out are shown in the figures by thick arrows, a pair of which is black and white, the other is solid black, accordingly. The first parameters may be different than second parameters in any of temperature, pressure, chemical composition, etc. Notwithstanding the given example, the terms first fluid may relate to the fluid of the same type, e.g. refrigerant, whereas the fluids of the same type may have different parameters, thus the heat exchange is possible. Alternatively, the first fluid may be of different type compared to the second fluid. Further paragraphs elaborate on the structure and characteristics of the heat exchanger 1. These characteristics are described based on the heat exchanger 1 working as IHX, which is suitable for a heat exchange between high-pressure fluids.
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The first fluid may be, for example, R744 or R290 circulating at first pressure and having first temperature, whereas the second fluid may be, for example, R744 circulating at second pressure and having second temperature, the first pressure being different than the second pressure and the first temperature being different than the second temperature.
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The heat exchanger 1 may comprise a plurality of first plates 100 stacked together in a first stacking direction. The stacking direction is normal to the general plane of at least one of the first plates 100. The standalone first plate 100 is shown in Fig.2.
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The first plates 100 may comprise a first wall 110. The first wall 110 may be formed around the circumference of each of the first plates 100. In other words, the first wall 110 is part of the first plate 100 which forms a periphery thereof, in relation to the general plane of the first plate 100.
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The plurality of the plates 100 are stacked one on the other so that the first walls 110 of consecutive first plates 100 are in contact with each-other. In other words, the two neighboring first plates 100 are in contact with each-other solely by their respective first walls 110. The first walls 110 are formed unitary with the first plate 100 in, for example, stamping process. In effect, the first plates 100 may be produced in greater volumes as they can be used for the formation of passages both for the first fluid and the second fluid.
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The heat exchanger 1 may further comprise a plurality of corrugated plates 200. The standalone corrugated plate 200 is shown in Fig.3.
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It is not surprising that, as the name implies, the corrugated plate 200 comprises corrugations 230. The corrugations 230 formed on each corrugated plate 200 may be formed in the stamping process and said corrugations 230 help determining intended flow path for the first fluid or the second fluid.
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The corrugated plate 200 may comprise an outlie edge 270. The outline edge 270 delimits is arranged at the perimeter of the corrugated plate 200 and delimits the outline thereof. As shown in Fig.3, the corrugated plate 200 may be delimited by the outline edge 270 being in a shape of rectangle with rounded edges. Other shapes of the outline edge 270 are also envisaged (e.g. oblong, rectangle, square, triangle).
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The first plates 100 and the second plates 200 may be assembled together along with a first end plate 301 and a second end plate 302 to form a core. A first plate 301 and a second plate 302 may be regarded as terminal plates of the core. The first plate 301 may be attached to the neighboring first plate 100. Similarly, the second end plate 302 may be attached to another neighboring first plate 100. The end plates 301, 302 may serve as the structural reinforcement for the heat exchanger 1. It is possible to attach the second plate 200 to any of the first or second end plate 301, 302 or both of them, yet such arrangement is not desired as it may weaken the core and consequently the entire heat exchanger 1.
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It is thus preferable that at least one of the corrugated plates 200 is sandwiched between neighboring first plates 100. Every pair of the first plates 100 may form a first passage 105 and/or the second passage 106, accordingly. It should be noted that particular first plate 100 may be forming the first passage 105 with one neighboring first plate 100, and the second passage 106 with another neighboring first tube 100. It is preferable that the first passages 105 are arranged alternately with the second passages 106, yet other arrangements of the first passages with respect to the second passages 106 are also envisaged.
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The first plates 100 together with corrugated plates 200 may also form a first pair of manifolds 101A, 101B for the first fluid, and a second pair of manifolds 102A, 102B for the second fluid. This allows the first fluid and the second fluid distribution throughout the core of the heat exchanger. Although the manifolds 101A, 101B 102A, 102B as such are formed by the assembly of multiple plates 100, 200, it should be noted that the term manifold 101A, 101B 102A, 102B in relation to standalone plate 100, 200 shall be regarded as opening which takes part in forming any of the manifolds 101A, 101B 102A, 102B in the heat exchanger 1. The first pair of manifolds 101A, 101B may be fluidly connected by at least one first passage 105, and the second pair of manifolds 102A, 102B may fluidly connected by at least one second passage 106. The manifolds 101A, 101B, 102A, 102B may be formed integrally with the core by providing the openings in the first plates 100 and the second plates which allow the fluid flow in a directions substantially parallel to the stacking direction of the plates 100, 200. The manifolds 101A, 101B, 102A, 102B may comprise a fixed hydraulic diameter throughout their entire length, the length being measured in parallel to the stacking direction of the plates. Alternatively, at least one of the manifolds 101A, 101B, 102A, 102B may comprise a variable hydraulic diameter. The hydraulic diameter may be changed, for example by changing making the opening in one of the plates smaller than other openings in the same, or other plates 100, 200. The intended first fluid flow path and intended second fluid flow path may be determined by the corrugations on the second plate 200.
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In order to provide a robust heat exchanger 1, the first plate 100 may further comprise a substantially planar portion 109. The planar portion 109 may be regarded as flat portion of the first plate 100 extending in a first direction, wherein the first direction is normal to the stacking direction of the plates 100, 200. The planar portion 109 may comprise openings forming the manifolds 101A, 101B, 102A, 102B, as in fact they are formed directly on said planar portion 109. The planar portion 109 is surrounded by the first wall 110 so that the first wall 110 protrudes directly form the planar portion 109 in a second direction being different than the first direction. In other words, the first wall 110 is not coplanar with the planar portion 109 as it extends in a different direction. This allows arranging the second plate 200 in-between the first plates 100 so that the overall size of the heat exchanger 1 is reasonable and such assembly in inexpensive to produce.
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The height of the first walls 110 in relation to the planar portion 109 may vary, depending on the desired size of the passages 105, 106. The first walls 110 may also be aligned in relation to the planar portion 109 at different angle. In other words, the size (e.g. hydraulic diameter) of the passages 105, 106, may be changed by adjusting the angle of the first wall 110, the size of the first wall 110, or by adjusting both of these parameters to the extent that the assembly of the two first plates 100 may withstand the pressure of the first and/or the second fluid.
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As mentioned in previous paragraphs, the corrugated plate 200 may comprise multiple corrugations 230 to direct the first fluid or the second fluid in the respective passages 105, 106. Fig. 4 shows the part of the heat exchanger 1 showing the corrugated plate 200 on the top of the stack of the first plates 100 and corrugated plates 200. It simply shows how corrugated plate 200 is plated on one of the adjacent first plates 100.
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Referring further to Fig. 3 and Fig. 4, the corrugations 230 may be divided into a main corrugation 230A, a structural corrugations 230B and also a collar 250 which will be discussed in further paragraphs.
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The main corrugation 230A is supposed to provide the flow path for any of the first or second fluid through the first pass 105 or second pass 106 respectively. The main corrugation 230A may be in fact several bumps which form several parallel channels between the manifolds 101A, 101B, 102A, 102B. In the example shown in Fig. 4, the main corrugation 230A extends between the first manifolds 101A, 101B. The main corrugation 230A may extend the flow path by providing several changes of direction of the intended fluid flow path. In the example shown if Fig. 4 this extension of fluid flow path is carried out, starting from first manifold 101A, by first L turn, next double L-turn (so basically a U-turn) and another L-turn which leads to the first manifold 101B. Analogically, the corrugated plate 200 may provide the above mention features between the second manifolds 102A, 102B.
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The structural corrugation 230B facilitate and strengthen the assembly of the heat exchanger 1 by providing additional brazing points between the adjacent first plates 100 and the corrugated plate 200 sandwiched in-between said first plates 100.
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As shown in Fig. 4, it is preferable that the corrugations 230 deflect the fluid in such way, that the path for said fluid is as long as possible, but not at the excessive cost of the pressure drop. In order to provide such path for the fluid, the corrugated plate 200 is in contact with at least one planar portion 109. The corrugated plate 200 may in contact with two planar portions 109 of neighboring first plates 100. Fig. 5 provides a detailed view of this arrangement.
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However, the corrugated plate 200 remains free from contact with the first wall 110 of the first plate 100. Thus, the corrugated plate 200 is separated from the first wall 110 by a non-null gap 900. The gap 900 may be measured, for example, in direction perpendicular to the first stacking direction. This allows arranging the second plate 200 between two neighboring first plates 100 without additional complicated structures. Ideally, the periphery of the corrugated plate 200 corresponds (overlaps) the planar portion 109. Preferably, the gap 900 measured between the first wall 110 and the corrugated plate 200 is the same at the entire circumference. Small deviations may be present, yet gap 900 generally allows arranging the second plate 200 equidistant to first wall 1.
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The first wall 110 may protrude beyond the outline delimited by the second plate 200 in a plane parallel to the planar portion 109, so that it is possible to encapsulate the second plate 200 by two neighboring first plates 100.
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In case the heat exchanger 1 is operating as the internal heat exchanger in which two high-pressure fluids circulate, more robustness is required. Usually it is the area in the vicinity of the manifolds 101A, 101B, 102A, 102B is prone to damage. In order to prevent failure of the heat exchanger.
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Accordingly, the corrugated plate 200 may comprise a collar 250. The collar 250 may surround at least one of the second of manifolds 102A, 102B. The collar 250 may also surround at least one of the first of manifolds 101A, 101B. On an individual corrugated plate 200, the collar 250 may surround the openings forming the first manifolds 101A, 101B. In this case, the openings forming the second manifolds 102A, 102B are devoid of collar 250. This allows fluidal communication between the second manifolds 102A, 102B through the second passage 106.
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Analogically, on the other individual corrugated plate 200, the collar 250 may surround the openings forming the second manifolds 102A, 102B. In this case, the openings forming the first manifolds 101A, 101B are devoid of collar 250. This allows fluidal communication between the first manifolds 101A, 101B through the first passage 105.
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It should be noted that the invention allows to limit the cost of the heat exchanger 1 by providing corrugated plates 200 which are identical. In the preferred embodiment, every second corrugated plate 200 is rotated relative to the adjacent corrugated plate 200 by 180 degrees, while the axis of rotation is determined parallel to the first stacking direction. This allows alternate arrangement of the corrugated plates, so that the heat exchange performance of the heat exchanger 1 is maximized.
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The collar 250 comprises multiple features which allow to further increase the robustness of the heat exchanger 1. The collar 250 may comprise a first portion 251 and a second portion 252. The first portion 251 may at least partially delimit the manifold 101A, 101B, 102A, 102B, and the second potion 252 may at least partially delimit the passage 105, 106, wherein the first portion 251 is connected directly to the second potion 252. In other words, the first portion 251 is configured to absorb the pressure of the fluid circulating in the 101A, 101B, 102A, 102B, whereas the second portion is configured to absorb the pressure of the fluid circulating in the first passage 105 or the second passage 106.
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Naturally, the first portion 251 and the second potion 252 are unitary with the corrugated plate 200. In other words, the first portion 251 and the second portion 252 are formed directly on the corrugated plate 200.
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As shown in Fig. 5 the first portion 251, the second potion 252 of the corrugated plate 200 and the planar portion 109 of the first plate 100 may together form a first zone 800. The first zone 800 is fluidly insulated from any of the first or second fluid. This allows further absorb the pressure from any of the first fluid and/or the second fluid. Furthermore the first zone 800 allows to reduce thermal stress in the vicinity of the manifolds 101A, 101B, 102A, 102B. The first zone 800 may be filled with the clad to further reinforce the connection of the first plate 100 with the corrugated plate 200.
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In order to provide for example the fluid- tight first zone 800, the corrugated plate 200 comprises may comprise a first flat section 211. The first flat section 211 protrudes directly from the first portion 251 and allows closing the gap between the first plate 100 and the corrugated plate 200 in the vicinity of respective manifolds 101A, 101B, 102A, 102B.
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Analogically, the corrugated plate 200 comprises a second flat section 212, wherein the second flat section 212 protrudes directly from the second section 252 and allows closing the gap between the first plate 100 and the corrugated plate 200 in the vicinity of respective first passage 105 or second passage 106.
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The number of the first plates 100 and the corrugated plates 200 may be different depending on the desired performance of the heat exchanger 1, yet in the preferable embodiment the number of collars 250 associated with the any of the manifolds 101A, 101B, 102A, 102B is half the number of the corrugated plates 200 present in the heat exchanger 1. This allows providing an optimized design.
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The heat exchanger 1 may also comprise means for ingress and egress of the first fluid and the second fluid. For instance, the first end plate 301 or the second end plate 302 may comprise at least one block 350. The block 350 may be a unitary piece of metal with the through-opening therein, wherein the block 350 is adapted to fluidly connect the heat exchanger 1 with respective loop, according to, for example, the interface provided by the customer. Naturally, the end plates 301, 302 are configured to provide a fluidal communication between the block 350 and respective manifold 101A, 101B, 102A, 102B.
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Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of drawings, the disclosure, and the appended claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to the advantage.