Patent Application
20240418457
The present application claims the benefit of and priority to German Patent Application No. 10 2024 109 696.9, filed Apr. 8, 2024 and German Patent Application No. 10 2023 115 332.3, filed Jun. 13, 2023, the entire contents of each of which are incorporated herein for all purposes by reference.
The invention relates to a plate heat exchanger for transferring heat between two fluids, in particular between a coolant and a refrigerant. The plate heat exchanger is provided for use in a refrigerant circuit, specifically in a refrigerant circuit in a vehicle. Furthermore, the invention relates to a use of the plate heat exchanger as an integrated gas cooler in a refrigerant compressor.
Plate heat exchangers are used for heat transfer in various fields of technology. Plate heat exchangers play an important role in air-conditioning systems with a refrigerant circuit, in particular in vehicle air-conditioning systems, since they need a comparatively small amount of space. Thanks to their compact design, plate heat exchangers allow efficient heat transfer between two fluids flowing in a materially separate manner through the plate heat exchanger. The individual plates between which flow paths for the fluids are formed can consist of different materials. The connection and sealing of the individual plates take place for example by means of joining methods such as welding, brazing or adhesive bonding. The selection of the plate and connection materials depends on the fluids used, the temperature ranges, the working pressures, and the predominant materials in the air-conditioning system. When using the material of the plate heat exchanger, corrosion-critical connections should be avoided with regard to the predominant materials in the fluid circuit of the air-conditioning system and the brazing material used, in order to ensure a long service life.
Plate heat exchangers consisting of deep-drawn or stamped aluminum or steel sheets are known in which the individual plates can have material thicknesses of less than 0.6 mm. The small plate thicknesses of the channel plates are advantageous because the channel structures for the flow paths can be formed in a simple manner by stamping. However, a material thickness that is too small results in a low internal pressure resistance, and therefore the operation of plate heat exchangers with correspondingly small plate thicknesses is suitable only for certain refrigerants. The stability and external pressure resistance of such plate heat exchangers are also limited by external force influences, since the stamped or deep-drawn channels can be compressed when under more intense loading so that the volumetric flow through the channels is no longer ensured. The possibilities for fastening for example by screw-fastening to the compressor are thus limited or can be ensured only by additional stabilization elements.
It is expected that the refrigerant R744 will replace conventional refrigerants in future, and therefore an increased demand for correspondingly pressure-resistant plate heat exchangers for the automotive field is likely. Therefore, a plate heat exchanger that combines the advantages of low weight with the advantages of increased pressure resistance and can be integrated in a refrigerant circuit of a vehicle is desirable.
The invention is therefore based on the object of proposing a compact and stable plate heat exchanger that has a low weight and withstands high operating pressures. The plate heat exchanger is to be designed in particular for use with the refrigerant R744 and for integration in a vehicle air-conditioning system. Furthermore, the plate heat exchanger is to be usable as an integrated gas cooler of a refrigerant compressor.
The object is achieved by a plate heat exchanger having the features shown and described herein.
A first aspect of the invention relates to a plate heat exchanger, which has channel plates with channel-forming cut-outs, of which at least two channel plates are in each case arranged into channel plate stacks, forming at least one channel. These channel plate stacks are divided into first channel plate stacks for a first fluid and second channel plate stacks for a second fluid. The first channel plate stacks for the first fluid and the second channel plate stacks for the second fluid are stacked alternatingly between two cover plates with separating plates arranged therebetween to separate opposing channels. At least one of the cover plates has fluid connections for the first and/or the second fluid. According to the invention, the channel-forming cut-out of in each case at least one channel plate of the first and second channel plate stacks has at least one stabilizing bridge oriented transversely to the channel.
In the plate heat exchanger according to the invention, the first channel plate stacks and the second channel plate stacks are stacked alternatingly, fluidically separated from one another, with separating plates between two cover plates. Each channel plate stack has at least one channel, which is covered by the separating plates or one of the two cover plates. Furthermore, each of the first and second channel plate stacks has first and second through-holes. The first through-holes of the second channel plate stacks correspond with the first through-holes of the first channel plate stacks and thus with the channels of the first channel plate stacks, as a result of which the first channel plate stacks are connected to one another. The first through-holes thus form a distributor channel or collection channel for the first fluid so that the first fluid can pass into the planes of the first channel plate stacks. The second through-holes of the first channel plate stacks correspond with the second through-holes of the second channel plate stacks and thus connect the channels of the second channel plate stacks so that the second channel plate stacks are connected fluidically to one another. The second through-holes thus form a distributor channel or collection channel for the second fluid so that the second fluid can pass into the planes of the second channel plate stacks. The first channel plate stacks thus form a first flow path for the first fluid, wherein the second channel plate stacks form a second flow path, which is separate from the first flow path, for the second fluid. In each case, at least one fluid connection as a fluid inlet and a further fluid connection as a fluid outlet are provided for each flow path. The fluid connections can have threads or be attached by brazing or welding.
According to the invention, the channel plate stacks are each formed from at least two channel plates that are stacked on top of one another and each have channel-forming cut-outs for forming at least one channel. In each case, at least one channel plate has, along a course of the channel-forming cut-out, at least one stabilizing bridge, which is oriented transversely to the channel and connects opposing flanks of the channel-forming cut-out to one another.
Within the meaning of the invention, the term “channel-forming cut-out” describes a usually elongate, track- or orbit-shaped through-hole in a channel plate. At least two channel plates stacked on top of one another form a corresponding cut-out that forms the at least one channel for the throughflow of the first or the second fluid when the resulting channel plate stack is arranged between two separating plates or between a separating plate and a cover plate. Accordingly, the channels formed from the channel-forming cut-outs of the first channel plate stacks have a fluid connection to the first through-holes of the second channel plate stacks, wherein the channels formed from the channel-forming cut-outs of the second channel plate stacks have a fluid connection to the second through-holes of the first channel plate stacks. To conduct the fluids, the separating plates likewise each have corresponding through-holes.
The channel plates, the channel-forming cut-outs, and the first and second through-holes can be formed using manufacturing methods such as punching, laser cutting or water jet cutting.
According to the invention, the channels for the throughflow of the first fluid and the second fluid separate therefrom are each formed in stacks of at least two channel plates, wherein in each case at least one channel plate of a channel plate stack has, along a course of the channel-forming cut-out of the channel plate in question, at least one stabilizing bridge oriented transversely to the channel. This stabilizing bridge forms an interruption of the channel-forming cut-out of the channel plate in question. Advantageously, this interruption acts as a supporting structural element that stabilizes the channel plate with the channel-forming cut-out formed therein and facilitates manufacturing, for example by punching. In this way, particularly delicate structures can be stabilized, which is advantageous in particular with small material thicknesses.
The individual first and second channel plate stacks are each separated by the separating plates or covered by the cover plates in a fluid-tight manner, wherein the separating plates or the cover plates cover opposing outer sides of the channel plate stacks. As a result, the at least one channel of a channel plate stack is also covered in a fluid-tight manner on both sides by separating plates or by a separating plate and a cover element.
The channel plates can be formed from steel or aluminum or an aluminum alloy, wherein aluminum is the preferred material owing to the lower weight. Advantageously, the use of thin channel plates consisting of aluminum helps to reduce weight without having to do without a necessary pressure resistance, with correspondingly dimensioned separating plates and cover plates. The separating plates and the cover plates can likewise be formed from aluminum and have a greater material thickness than a channel plate of the first and second channel plate stacks. An improved pressure resistance can thus be ensured within the plate heat exchanger, since the material thickness of the separating plates and the cover plates can be adapted to a necessary pressure resistance. The separating plates and the cover plates contain the first through-holes necessary for the fluid connection of the first channel plate stacks and the second through-holes necessary for the fluid connection of the second channel plate stacks. Each first channel plate stack thus has a second through-hole for directly conducting the second fluid, wherein each second channel plate stack has a first through-hole for directly conducting the first fluid. The totality of the first through-holes forms a distributor channel or a collection channel for the first fluid, wherein the totality of the second through-holes forms a distributor channel or a collection channel for the second fluid.
It has been found that production of the channel plates by punching is simplified in manufacturing terms when the thickness of the sheet out of which the channel plates are punched is in the range of 1 mm to 0.6 mm. Accordingly, the individual channel plates of the first and second channel plate stacks can have a thickness in the range of 1 mm to 0.6 mm.
The connection of the individual channel plates to one another and to the separating plates and/or the cover plates can be produced by a joining method such as brazing, welding or adhesive bonding. In the case of brazing, the use of a suitable brazing metal must be ensured, to avoid connections susceptible to corrosion.
The individual channel plates, the separating plates, the cover plates, and the connection between the plates can be dimensioned such that the plate heat exchanger withstands an operating pressure of 200 bar.
The channel height of the at least one channel of the first and second channel plate stacks is defined by the number of channel plates and the material thickness of the channel plates. The channel height is limited by two separating plates or a separating plate and a cover plate. The channel height is influenced only at positions at which a channel-forming cut-out of one of the channel plates of the channel plate stack in question has a stabilizing bridge. The stabilizing bridges present along the at least one channel locally reduce the flow cross section of the channel formed, as a result of which the flow speed and the turbulence are advantageously increased and thus the heat transfer is improved. If there are multiple parallel individual channels, the distribution of the fluid flowing through can advantageously be influenced by the number of stabilizing bridges and the length of the individual stabilizing bridges, in order to ensure improved heat transfer.
According to a preferred embodiment of the plate heat exchanger, in which the first and second channel plate stacks are each formed from multiple stacked channel plates, it can be provided for each second channel plate to have at least one stabilizing bridge oriented transversely to the channel. In this case, the channel plates with stabilizing bridge and the channel plates that do not have any stabilizing bridges in their channel-forming cut-out can be arranged alternatingly. Channel plates A with stabilizing bridge and channel plates B that do not have any stabilizing bridges can be arranged in the stacking order A-B-A-B.
According to a further embodiment of the plate heat exchanger, each channel plate of the first channel plate stacks and of the second channel plate stacks can have a stabilizing bridge oriented transversely to the at least one channel, wherein the stabilizing bridges of channel plates stacked on top of one another are offset along the course of the at least one channel. In other words, the stabilizing bridges are offset such that a fluid flow through the channel formed is not blocked. Channel plates A with stabilizing bridge and channel plates C in which the stabilizing bridge is formed at a different position in the channel-forming cut-out can be arranged in the stacking order A-C-A-C. Also possible are combined stacking orders with channel plates B, which do not have any stabilizing bridges. Stacking orders such as A-B-C-A-B-C and further combinations can result from this.
According to the invention, the channel-forming cut-out of a channel plate is stabilized by the at least one stabilizing bridge, wherein a channel-forming cut-out that results in the formation of a long channel within the channel plate stack has more than just one stabilizing bridge. This means: The longer the channel, the greater the number of stabilizing bridges of a channel-forming cut-out can be. A channel-forming cut-out of a channel plate can thus have a plurality of the stabilizing bridges.
Dimensioning of the at least one stabilizing bridge of the channel-forming cut-out of a channel plate can depend on the width of the channel formed by the channel-forming cut-out. The at least one stabilizing bridge can thus have a width that corresponds at least to the width of the at least one channel formed. However, as already mentioned above, the stabilizing bridge can also be much wider than the width of the channel in order to influence the flow through the channel in question.
The channel plates can each have multiple channel-forming cut-outs, which each form a channel structure having multiple individual channels, wherein each individual channel has at least one stabilizing bridge oriented transversely to the individual channel. The multiple individual channels can be arranged regularly or irregularly. Preferably, the individual channels of the channel structure are arranged adjacently in parallel at a distance from one another. The individual channels of the channel structure can originate from a common channel stack inlet and lead into a common channel stack outlet. The channel stack inlet and the channel stack outlet of a channel plate stack correspond with through-holes formed in the separating plates, i.e., with the respective first and second through-holes.
According to a preferred embodiment of the channel plates, it can be provided for a plurality of the channel-forming cut-outs to be formed such that they are arranged in concentric rings, so that the stacked channel plates form multiple spaced ring-shaped individual channels. In this case, the stabilizing bridges of adjacent ring-shaped channel-forming cut-outs can be radially offset. It has been found that production is simplified by the radially offset arrangement of the stabilizing bridges. The radially offset arrangement of the stabilizing bridges is also advantageous for the stability of the delicate structure of the channel-forming cut-outs. In this embodiment too, the stabilizing bridges of the channel-forming cut-outs are offset along a formed channel of stacked channel plates such that a fluid throughflow is ensured. The channel plates thus formed can be arranged as first channel plate stacks and/or as second channel plate stacks. The ring-shaped individual channels can have a common inlet and a common outlet, wherein the common inlet and the common outlet are each formed with first through-holes and second through-holes, respectively. It can also be provided in this embodiment of the channel plates for a width of the ring-shaped channel-forming cut-outs to decrease from the outside inwards. This means that the multiple concentric rings formed by the ring-shaped cut-outs have different widths, wherein the width of the ring-shaped cut-outs decreases from the outer ring to the inner ring. The ring-shaped individual channels then formed when the channel plates are stacked thus have a flow cross section that decreases from the outer ring-shaped individual channel to the inner ring-shaped individual channel. The individual channels formed then each have different widths and cross sections. It has been found that an improved distribution of the fluid flowing through is achieved by this measure, which results in an even better heat transfer performance.
The surface contact of the individual channel plates, the separating plates and the cover plates allows a particularly compact and stable design of the plate heat exchanger. The improved stability allows screw-fastening to components of a refrigerant circuit, in particular to a refrigerant compressor of a refrigerant circuit, without additional stabilization elements being required. The channel plates, separating plates and cover plates can thus each have multiple corresponding bushings for screws or bolts. These screw bushings or bolt bushings are provided to screw the plate heat exchanger directly to the refrigerant compressor, for example. The bushings for the screws or bolts are preferably arranged at the edges and distributed as evenly as possible in order to achieve uniform force distribution during screw-fastening. Thanks to the compact design of the plate heat exchanger, the channels formed remain leakproof and dimensionally stable even under external force effects as can occur during screw-fastening.
The channel-forming cut-outs can have a shape that forms at least one channel having an at least partially serpentine course. In this respect, a channel structure in which multiple individual channels running next to one another have an at least partially serpentine course can also be provided.
According to one embodiment of the plate heat exchanger according to the invention, the cover plates, the first and second channel plate stacks, and the separating plates arranged therebetween can have a substantially circular basic shape, wherein the fluid connections for the first fluid and/or for the second fluid are formed at the radial circumference of the plate heat exchanger. In this embodiment, the plate heat exchanger has a cylindrical shape, wherein the fluid connections for a first fluid are formed on a protrusion projecting from the circumference of the cylindrical shape. The fluid connections for a second fluid can be formed in the cover plates. A first fluid connection can be designed as a fluid inlet for the first fluid in a first cover element, wherein a second fluid connection is designed as a fluid outlet for the first fluid in a second cover element. This embodiment of the plate heat exchanger is suitable in particular for integration in a refrigerant compressor in a refrigerant circuit.
The plate heat exchanger according to the invention allows an arrangement for parallel or serial flow of the fluids through multiple channel plate stacks. The first channel plate stacks and, fluidically separately therefrom, the second channel plate stacks can thus be fluidically connected in series or in parallel.
Thanks to the invention, a high-pressure-resistant and compact plate heat exchanger with low weight is provided. Delicate channel structures in robust channel plates that are suitable for punching and are arranged to form channel plate stacks allow high heat transfer performance while keeping production costs low.
A further aspect of the invention is the use of the above-described plate heat exchanger in a refrigerant circuit having refrigerant R744.
A still further aspect of the invention is the use of the plate heat exchanger as an integrated gas cooler in a refrigerant compressor, specifically in a refrigerant compressor of a vehicle. The plate heat exchanger can assume the function of an inner heat exchanger in the case of multi-stage compression. According to this use of the plate heat exchanger, the plate heat exchanger can be arranged downstream of a compression stage and screw-fastened to the refrigerant compressor so that the plate heat exchanger is situated on the refrigerant outlet side of the refrigerant compressor.
The plate heat exchanger according to the invention has even more advantages. For instance, the pulsations on the refrigerant outlet side of a refrigerant compressor are damped by the internal additional volume of the plate heat exchanger downstream of the compression stage in the refrigerant compressor, and a reduced noise emission of the refrigerant compressor in the vehicle is achieved as a result. In addition to the pulsation damping by means of the internal volume of the plate heat exchanger, the inner structure of the channel-forming cut-outs with the stabilizing bridges is formed such that the pulsations in the parallel individual channels interfere destructively owing to the different run lengths and thus result in a reduction in pulsations generated by the refrigerant compressor. This also results in a reduction in the noise emission of the refrigerant compressor. The plate heat exchanger according to the invention can therefore be used additionally as a muffler. Therefore, when the plate heat exchanger is used in a refrigerant circuit, for example as an integrated gas cooler in a refrigerant compressor, specifically in a refrigerant compressor of a vehicle, an additional muffler is not necessary, since damping and reduction of the noise emission can be ensured by the plate heat exchanger. The plate heat exchanger can thus be used as a muffler in air-conditioning systems having refrigerant compressors.
Further details, features and advantages of embodiments of the invention can be found in the description of exemplary embodiments below with reference to the associated drawings. In the drawings:
Recurring features are labelled with the same reference signs in the figures.
The channel plates 1.1 and 1.2 also have corresponding second through-holes 6, which serve for fluid connection of second channel plate stacks 2, which are not shown in the diagram.
The individual channel plates 1.1, 1.2 and 2.1 and 2.2 of
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 115 332.3 | Jun 2023 | DE | national |
| 10 2024 109 696.9 | Apr 2024 | DE | national |
