PLATE HEAT EXCHANGER

TECHNICAL FIELD

[0001]The invention relates to the field of heat exchangers. More particularly, it is related to a plate heat exchanger.

[0002]The plate heat exchanger has first heat exchanger plates and second heat exchanger plates forming first plate interspaces configured to receive a first fluid and second plate interspaces configured to receive a second fluid. The first heat exchanger plates and the second heat exchanger plates are stacked onto one another.

BACKGROUND ART

[0003]Plate heat exchangers are used in numerous applications where heat is to be transferred from one fluid to another or vice versa.

[0004]A typical plate heat exchanger includes a plate package formed of stacked heat exchanger plates. Generally, a number of first heat exchanger plates and a number of second heat exchanger plates are stacked in an alternating fashion and joined to each other. In this way a first plate interspace is formed between each pair of adjacent first heat exchanger plates and second heat exchanger plates and a second plate interspace between each pair of adjacent second heat exchanger plates and first heat exchanger plates. The first plate interspaces and the second plate interspaces are typically separated from each other and are designed to receive a respective fluid between which fluids heat is to be exchanged. To this end, respective inlet and outlet ports are typically provided to the first plate interspaces and to the second plate interspaces.

[0005]One common type of plate heat exchanger of the above kind is a so-called evaporator. An evaporator is generally a plate heat exchanger designed for evaporation of a fluid in a refrigeration system. Such refrigeration system may by way of example be an air conditioning system, a cooling system, a heat pump system or similar. Typically, such a refrigeration system comprises, in addition to an evaporator, a compressor, a condenser and an expansion valve, all of which are coupled in series.

[0006]Since a fluid, such as a refrigerant supplied to an inlet channel of such an evaporator, is normally present both in a gaseous state and a liquid state, the evaporator is also commonly referred to as a two-phase evaporator. In other words, the fluid supplied to the inlet channel of the evaporator is generally provided in two states of aggregation simultaneously, namely liquid and vapor. When fluid is supplied both in a gaseous state and a liquid state it is difficult to provide an even or optimal distribution of the fluid to the different plate interspaces. One reason for this can be that the fluid, after having passed through the expansion valve, is already partly evaporated when it enters the inlet channel of the evaporator. This can result in that the fluid does not remain in a state of a homogenous liquid/vapor mixture during the passage along the whole length of the inlet channel but tends to partly separate into streams of liquid and vapor, respectively. Hence, some plate interspaces may receive more liquid than others and some plate interspaces may receive more vapor than others.

[0007]Uneven distribution of fluid to the different plate interspaces and hence the evaporation flow paths provided therein generally results in a reduced overall performance of the plate heat exchanger. Moreover, the fluid may become unnecessarily overheated. Furthermore, some flow paths may be filled by fluid in the liquid phase meaning that there is a risk that some fluid in the liquid phase may exit the evaporator through its outlet channel. This should be avoided due to the risk of liquid entering, for instance, a compressor.

[0008]To this end, it has been suggested to provide restriction parts or restriction openings in conjunction to each passage between the inlet channel of the plate heat exchanger and its associated plate interspace forming an evaporation flow path for the fluid. The provision of restriction parts has proven troublesome when it comes to manufacturing, mainly because such parts must be correctly placed and fixed in each relevant place interspace. Provision of restriction openings is generally more favorable from a manufacturing perspective but tends to suffer from other drawbacks. Often when making a restriction opening there is a risk of cracks forming in the plate, especially when the restriction opening hole has a small diameter. Such cracks may especially appear in a collar generally surrounding the port hole. If such collar cracks there is a risk that fluid will enter the plate interspaces through the crack, which will inevitably lower the function and performance of the heat exchanger.

[0009]Hence, there is room for improvement when it comes to evenly distributing fluid in a plate heat exchanger such as an evaporator.

SUMMARY

[0010]With the above in mind, it is an object of the present invention to provide an improved plate heat exchanger.

[0011]Another object is to provide such a plate heat exchanger in which a fluid is distributed more evenly throughout the plate interspaces of the plate heat exchanger.

[0012]Another object is to provide such a plate heat exchanger which has an improved overall performance.

[0013]Another object is to provide such a plate heat exchanger which is capable of handling higher fluid speeds to satisfaction.

[0014]Another object is to provide such a plate heat exchanger which enables an improved mixing of fluid in a liquid phase and fluid in gaseous phase.

[0015]Another object is to provide such a plate heat exchanger which is less prone to cracking.

[0016]Another object is to provide such a plate heat exchanger which is easier to manufacture.

[0017]Another object is to provide such a plate heat exchanger which is more cost-effective.

[0018]To achieve at least one of the above objects and also other objects that will be evident from the following description, a plate heat exchanger, having the features defined in claim 1 is provided according to the present inventive concept.

[0019]More specifically, according to a first aspect, there is provided a plate heat exchanger comprising: first heat exchanger plates and second heat exchanger plates forming first plate interspaces configured to receive a first fluid and second plate interspaces configured to receive a second fluid, wherein the first heat exchanger plates and the second heat exchanger plates are vertically stacked onto one another in a vertical direction and extending in parallel with a horizontal extension plane, wherein each first and second exchanger plate comprises a porthole extending therethrough, such that a port hole channel is formed in the vertical direction through the first heat exchanger plates and the second heat exchanger plates via the portholes, wherein a first heat exchanger plate and a second heat exchanger plate are joined in a fluid thigh manner via a first joining area circumscribing the port hole channel at a first radial distance from a center of the port hole channel thereby forming a first peripheral plate portion of the first heat exchanger plate extending between the first joining area and the port hole channel, and a second peripheral plate portion of the second heat exchanger plate extending between the first joining area and the port hole channel, the first peripheral plate portion and the second peripheral plate portion circumscribing the port hole channel and at least partially extending at a distance from each other in the horizontal direction, wherein a first section of the first peripheral plate portion extends towards the second peripheral plate portion and/or wherein a first section of the second peripheral plate portion extends towards the first peripheral plate portion at a second radial distance from the center of the port hole channel thereby forming a restricted volume between the first peripheral plate portion and the second peripheral plate portion between the first radial distance and the second radial distance, the restricted volume being in fluid communication with the port hole channel.

[0020]Hereby an improved plate heat exchanger is provided.

[0021]Thus, the present invention is based on the realization that by forming a restricted volume in fluid communication with the port hole channel, an improved mixing of fluid entering the port hole channel may be achieved prior to feeding the fluid to a plate interspace. More specifically, a restricted volume in fluid communication with the port hole channel may be formed between the first peripheral plate portion and the second peripheral plate portion between the first radial distance and the second radial distance. In this way, the fluid entering the port hole channel may be more evenly distributed throughout the plate heat exchanger. In other words, the fluid may be more evenly distributed in the vertical direction as well as along the horizontal extension plane. Thus, the fluid may be more evenly distributed between the respective relevant plate interspaces as well as more evenly distributed within said relevant plate interspaces. At the same time plates of the plate heat exchanger may be less prone to cracking or otherwise being damaged. Moreover, the plate heat exchanger may be capable of handling high fluid speeds enabling a high degree of mixing.

[0022]By a first heat exchanger plate and a second heat exchanger plate being joined in a fluid thigh manner via a first joining area circumscribing the port hole channel at a first radial distance from a center of the port hole channel, a first peripheral plate portion of the first heat exchanger plate is formed and a second peripheral plate portion of the second heat exchanger plate is formed. It should be noted that within the context of this application the term “peripheral plate portion”, such as the first peripheral plate portion and the second peripheral plate portion, may mean any portion of any heat exchanger plate which is located between the first sealing area and the port hole channel, including any portion of any heat exchanger plate at least partially defining a port hole channel. Hence, such peripheral plate portion may have any shape and may include a plurality of sections or subsections extending in different directions or orientations. Thus, such peripheral plate portion may be formed to provide a desired functionality such as forming the restricted volume between the first peripheral plate portion and the second peripheral plate portion between the first radial distance and the second radial distance. Further, such peripheral plate portion may be formed to provide a desired functionality or shape of the port hole channel.

[0023]The first peripheral plate portion extends between the first joining area and the port hole channel. The second peripheral plate portion of the second heat exchanger plate extends between the first joining area and the port hole channel. The first peripheral plate portion and the second peripheral plate portion circumscribing the port hole channel. Moreover, the first peripheral plate portion and the second peripheral plate portion and at least partially extending at a distance from each other in the horizontal direction such that a space, like the restricted volume, or more than one space is formed between the first peripheral plate portion and the second peripheral plate portion.

[0024]A first section of the first peripheral plate portion extends towards the second peripheral plate portion and/or a first section of the second peripheral plate portion extends towards the first peripheral plate portion at a second radial distance from the center of the port hole channel thereby forming the restricted volume. It should be noted that within the context of this application the term “section”, such as the first second of the first peripheral plate portion and the second section of the second peripheral plate portion, may mean any section, part or subset of its associated peripheral plate portion. In other words, a section forms part of a peripheral plate portion. Correspondingly, a peripheral plate portion may be said to be formed of a plurality of sections.

[0025]It should be noted that within the context of this application the term “restricted volume” may mean any volume or space which has a principal cross-sectional area that is larger than a cross-sectional area of an opening, slit or similar through which the restricted volume is accessible. Hence, the restricted volume is accessible through one or more narrowings, like an opening, a passage, a slit, or similar.

[0026]A first opening may be provided between the restricted volume and a first plate interspace, which is advantageous in that fluid may be fed via the restricted volume to the first plate interspace. By feeding fluid to the first plate interspace via the restricted volume, an improved distribution and a further improved mixing of the fluid may be achieved. In other words, the fluid may be distributed more evenly between the first plate interspaces. Further, mixing of liquid and vapor may be further improved by feeding fluid to the first plate interspace via the restricted volume.

[0027]The first section of the first peripheral plate portion and the first section of the second peripheral plate portion may meet and be joined in a fluid tight manner at the second radial distance via a second joining area, the second joining area comprising a discontinuance forming a second opening between the port hole channel and the restricted volume thereby providing for said fluid communication, which is advantageous in that distribution and/or mixing of liquid and vapor may be further improved. In practice, the fluid communication between the port hole channel and the restricted volume may be controlled by tailoring the second opening. Hence, fluid including both liquid and vapor may be fed to the restricted volume via the second opening while being distributed and/or mixed more efficiently.

[0028]The second opening may be formed by a notch in the first peripheral plate portion at the second joining area and/or in the second peripheral plate portion at the second joining area, which is advantageous in that the second opening may be provided in an efficient manner while forming the first and/or the second heat exchanger plates. Hence, the second opening may be formed by e.g. pressing a notch at a location where the second joining area is to be formed while forming the first and/or the second heat exchanger plates.

[0029]A circumferential extension of the restricted volume may be delimited by a pair of protrusions provided in the first peripheral plate portion and/or in the second peripheral plate portion, the protrusions extending radially between the first joining area and the second joining area, which is advantageous in that mixing of liquid and vapor may be further improved. By delimiting the circumferential extension of the restricted volume, pressure may build up quicker in the restricted volume and thereby promote a more efficient distribution and/or mixing of liquid and vapor. Further, by delimiting the circumferential extension of the restricted volume by a pair of protrusions, such delimiting may be provided in an efficient manner while forming the first and/or the second heat exchanger plates.

[0030]The first peripheral plate portion may further comprise a first end section at least partially defining the port hole channel and extending substantially along the vertical direction, which is advantageous in that the interior of the port hole channel may at least partially be shaped by the first end section. In practice, the interior of the port hole channel may be made smooth or flat or less irregular which promotes an even distribution of liquid and vapor in the port hole channel.

[0031]The second peripheral plate portion may further comprise a second end section at least partially defining the port hole channel and extending substantially along a direction opposite to the vertical direction, which is advantageous in that the interior of the port hole channel may at least partially be shaped by the second end section. In practice, the interior of the port hole channel may be made smooth or flat or less irregular which promotes an even distribution of liquid and vapor in the port hole channel.

[0032]A vertical extension of the first end section may be equal to a vertical extension of the second end section, or the vertical extension of the first end section may be smaller than the vertical extension of the second end section. By lettering the vertical extension of the first end section be equal to the vertical extension of the second end section, a smooth or flat or less irregular port hole channel may be achieved. By letting the vertical extension of the first end section be smaller than the vertical extension of the second end section, a port hole channel which promotes a flow of fluid in one direction, i.e. opposite to the vertical direction, with a reduced flow resistance and/or undesired turbulence may be achieved.

[0033]The first end section and second end section may be provided at a same radial distance from the center the port hole channel, or the first end section may be provided at a larger radial distance from the center of the port hole channel than the second end section. By providing the first end section and second end section at the same radial distance from the center the port hole channel the interior of the port hole channel may be made smooth or flat or less irregular which promotes an even distribution of liquid and vapor in the port hole channel. By providing the first end section at a larger radial distance from the center of the port hole channel than the second end section a port hole channel which promotes a flow of fluid in one direction, i.e. opposite to the vertical direction, with a reduced flow resistance and/or undesired turbulence may be achieved.

[0034]The second end section may overlap the first end section as seen from the port hole channel. Hence, the second end section may be located closer to the center of the port hole channel as compared to the first end section.in this way, a port hole channel which promotes a flow of fluid in one direction, i.e. opposite to the vertical direction, with a reduced flow resistance and/or undesired turbulence may be achieved.

[0035]The port hole channel may have a diameter of 3-50 mm, preferably, 4-30 mm, more preferably 5-24 mm.

[0036]The first opening may have a cross sectional area of 0.1-1.0 mm², preferably 0.25-0.55 mm², more preferably 0.35-0.45 mm², which is advantageous in that a desired mixing and flow resistance may be achieved. By having a relatively speaking small first opening, the flow speed of the fluid through the first opening may be increased. Such increased flow speed may improve mixing of liquid and vapor of the fluid.

[0037]The second opening may have a cross sectional area of 1-15 mm², preferably 1.5-10 mm², more preferably 2-5 mm², which is advantageous in that the second opening may provide for an efficient distribution and/or mixing of liquid and vapor of the fluid while still promoting an efficient flow of fluid via the restricted volume. Hence, the pressure drop over the second opening may be reduced or at least acceptable by the above cross sectional area of the second opening.

[0038]The first joining area may be formed by a joining a first horizontal section of the first peripheral plate portion with a first horizontal section of the second peripheral plate portion, which is advantageous in that brazing or welding of the plate heat exchanger may be facilitated. By forming the first joining area by a joining the first horizontal section of the first peripheral plate portion with the first horizontal section of the second peripheral plate portion, solder or braze material may be screen-printed on the first horizontal sections prior to brazing the plate heat exchanger. Hence, fabrication of the plate heat exchanger may be facilitated.

[0039]The second joining area may be formed by a joining a second horizontal section of the first peripheral plate portion with a second horizontal section of the second peripheral plate portion which is advantageous in that brazing or welding of the plate heat exchanger may be facilitated. By forming the second joining area by a joining the second horizontal section of the first peripheral plate portion with the second horizontal section of the second peripheral plate portion, solder or braze material may be screen-printed on the second horizontal sections prior to brazing the plate heat exchanger. Hence, fabrication of the plate heat exchanger may be facilitated.

[0040]A further first opening may be provided between the restricted volume and the first plate interspace and/or a further second opening may be provided between the port hole channel and the restricted volume. By providing a further first opening between the restricted volume and the first plate interspace, fluid may be fed into the first plate interspace at multiple locations thereby providing for an improved distribution of the fluid within the first plate interspace. By providing a further second opening between the port hole channel and the restricted volume, fluid may be fed into the restricted volume at multiple locations thereby providing for an improved mixing of liquid and vapor of the fluid.

[0041]The further first opening and the further second opening may extend along a same radial direction of the port hole channel.

[0042]The first opening and the further first opening may extend along different radial directions of the port hole channel. The different radial directions of the first opening and the further first opening may be separated by an angle of 10-180 degrees. The different radial directions of the first opening and the further first opening may be separated by an angle of 30-120 degrees.

[0043]The first opening and the further first opening may extend along the same radial direction of the port hole channel.

[0044]The second opening and the further second opening may extend along different radial directions of the port hole channel. The different radial directions of the second opening and the further second opening may be separated by an angle of 10-180 degrees. The different radial directions of the second opening and the further second opening may be separated by an angle of 30-120 degrees.

[0045]The second opening and the further second opening may extend along the same radial direction of the port hole channel.

[0046]A further scope of applicability of the present invention will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

[0047]Hence, it is to be understood that this invention is not limited to the particular component parts of the device described as such device may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claim, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to “a unit” or “the unit” may include several devices, and the like. Furthermore, the words “comprising”, “including”, “containing” and similar wordings does not exclude other elements or steps.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048]The above and other aspects of the present inventive concept will now be described in more detail, with reference to appended figures showing variants. The figures should not be considered limiting, instead, they are used for explaining and understanding.

[0049]As illustrated in the figures, the sizes of layers and regions may be exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of variants. Like reference numerals refer to like elements throughout.

[0050]FIG. 1A is a schematic exemplary side view of a plate heat exchanger.

[0051]FIG. 1B is an exemplary schematic cross sectional top view of the plate heat exchanger of FIG. 1A.

[0052]FIG. 2 is an exemplary partial perspective view of a corner region of plate heat exchanger illustrating a stack of heat exchanger plates and a port hole channel.

[0053]FIG. 3A is an exemplary partial cross sectional perspective view illustrating a cross section through a port hole channel region of a heat plate heat exchanger according to an embodiment.

[0054]FIG. 3B is an exemplary elevated partial perspective view illustrating a port hole channel region of the heat plate heat exchanger of FIG. 3A.

[0055]FIG. 3C is an enlarged partial view of FIG. 3A.

[0056]FIG. 4 is an exemplary elevated partial perspective view illustrating a port hole channel region of a heat plate heat exchanger according to an embodiment.

[0057]FIG. 5 is an exemplary partial cross sectional perspective view illustrating a cross section through a port hole channel region of a heat plate heat exchanger according to an embodiment.

[0058]FIG. 6 is an exemplary partial cross sectional perspective view illustrating a cross section through a port hole channel region of a heat plate heat exchanger according to an embodiment.

[0059]FIG. 7 is an exemplary partial cross sectional perspective view illustrating a cross section through a port hole channel region of a heat plate heat exchanger according to an embodiment.

[0060]FIG. 8 is an exemplary partial cross sectional perspective view illustrating a cross section through a port hole channel region of a heat plate heat exchanger according to an embodiment.

DETAILED DESCRIPTION

[0061]The present inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred variants or embodiments of the inventive concept are shown. This inventive concept may, however, be implemented in many different forms and should not be construed as limited to the variants set forth herein; rather, these variants are provided for thoroughness and completeness, and fully convey the scope of the present inventive concept to the skilled person.

[0062]Example embodiments of a plate heat exchanger 10 will in the below be described with reference to the drawings. The drawings are only schematic and the relative dimensions of some structures and layers may be exaggerated and not drawn to scale. Rather the dimensions may be adapted for illustrational clarity and to facilitate understanding. When present in the figures, the indicated axes H and V consistently refer to a horizontal or lateral direction H of the plate heat exchanger 10 and vertical direction V of the plate heat exchanger 10. The term “horizontal” direction H refers to any directions parallel to an extension plane P of the heat exchanger plates of the plate heat exchanger 10. The term “vertical” direction V refers to a direction parallel to a normal direction of the extension plane P of the heat exchanger plates of the plate heat exchanger 10. Further, the (positive) vertical direction refers to a direction which points out of what typically is regarded a lower end plate of the plate heat exchanger 10. This means that fluid entering and exiting the plate heat exchanger 10 through ports thereof, in the depicted embodiments enters and exits the plate heat exchanger 10 in negative vertical direction, i.e., a direction which is opposite to the vertical direction. However, according to embodiments, fluid may enter or exit the plate heat exchanger 10 in the positive vertical direction and/or in the negative vertical direction.

[0063]Now turning to FIGS. 1A, 1B and 2. FIGS. 1A and 1B schematically illustrate by way of example an exemplary plate heat exchanger 10. The plate heat exchanger 10 includes a plate package, which is formed by a number of heat exchanger plates 100, 200. The heat exchanger plates 100, 200 are typically formed from sheet metal which is cut to size and pressed to the shape of the heat exchanger plates 100, 200. The heat exchanger plates 100, 200 are stacked on top of each other in a stacking direction. In the depicted plate heat exchanger 10, the heat exchanger plates are stacked in the vertical direction V. The plate heat exchanger 10 comprises two different types of heat exchanger plates, which in the following are referred to as first heat exchanger plates 100, and the second heat exchanger plate 200. The plate package includes substantially the same number of first heat exchanger plates 100 and second heat exchanger plates 200. As is clear from FIG. 1A, the heat exchanger plates 100, 200 are provided on top of each other in such a way that a first plate interspace 11 is formed between each pair of adjacent first heat exchanger plates 100 and second heat exchanger plates 200, and a second plate interspace 12 between each pair of adjacent second heat exchanger plates 200 and first heat exchanger plates 100.

[0064]Every second plate interspace thus forms a respective first plate interspace 11 and the remaining plate interspaces form a respective second plate interspace 12, i.e., the first and second plate interspaces 11, 12 are provided in an alternating order in the plate package of the plate heat exchanger 10. Furthermore, the first and second plate interspaces 11, 12 are separated from each other. The first plate interspaces 11 are configured to receive a first fluid and second plate interspaces 12 configured to receive a second fluid.

[0065]According to a non-limiting example, the plate heat exchanger 10 may advantageously be configured to operate as an evaporator in a cooling agent circuit, not disclosed. In such an evaporator application, the first plate interspaces 11 may form first passages for the first fluid being a refrigerant whereas the second plate interspaces 12 may form second passages for a second fluid, which is to be cooled by the first fluid.

[0066]According to a non-limiting example, the plate heat exchanger 10 may also be reversed, and is then configured to be operated as a condenser, wherein the first fluid, i.e. the refrigerant, is condensed in the first plate interspaces 11, and the second fluid is conveyed through the second plate interspaces 12 for cooling the first fluid conveyed through the first plate interspaces 11.

[0067]The depicted plate heat exchanger 10 of FIGS. 1A and 1B is provided with an upper end plate 11 and a lower end plate 12, which are provided on a respective side of the plate package of the plate heat exchanger 10.

[0068]In the depicted heat exchanger 10 the heat exchanger plates 100, 200 and the end plates 6, 7 are permanently joined to each other. Such a permanent joining may advantageously be performed through brazing, welding, use of an adhesive or bonding. During joining by means of brazing a suitable number of heat exchanger plates are typically stacked on top each other with a solder or braze material, such as copper or a copper alloy, located between adjacent heat exchanger plates 100, 200, at desired locations. The first and second heat exchanger plates 100, 200 may to advantage be made of a metal or a metal alloy, such as stainless steel, which extends to the outer surface of the heat exchanger plates 100, 200. The outer surface of the metal or metal alloy typically has such properties that it adheres to the solder or braze material during the brazing of the plate heat exchanger 10. During such brazing the whole plate package of the plate heat exchanger 10 is heated in an oven until said solder or braze material melts. This will result in a permanent joint between the heat exchanger plates 100, 200 of the plate heat exchanger 10.

[0069]As schematically depicted in FIG. 1B, each heat first and second exchanger plates 100, 200 has four portholes 153.

[0070]First portholes 150 form a port hole channel 152 in form of a first inlet channel 152 to the first plate interspaces 11. The port hole channel 152 is illustrated in greater detail in FIG. 2 to which reference is also made. The first plate interspaces 11 are configured to receive the first fluid entering the first plate interspaces 11 via the port hole channel 153 as is known in the art. The port hole channel 152 extends through substantially the whole plate package of the plate heat exchanger 10. That is, the port hole channel 152 typically extends through all the first and second heat exchanger plates 100, 200 and through the upper end plate 11. Correspondingly, port hole channels are formed by the other portholes 153, of which one port hole channel is an outlet channel for the first fluid. Another one port hole channel is an inlet channel to the second plate interspaces 12. The second plate interspaces 12 are configured to receive a second fluid entering the second plate interspaces 12 via its associated port hole channel as is known in the art. The final port hole channel is an outlet channel for the second fluid.

[0071]The four portholes 153 are in the depicted embodiment of FIGS. 1A, 1B and 2 provided in the proximity of a respective corner of the substantially rectangular heat exchanger plates 100, 200. It is, however, to be understood that other positions are possible.

[0072]FIG. 2 schematically illustrates a perspective view of a corner region of a plate heat exchanger 10 like the plate heat exchanger 10 of FIGS. 1A and 1B, with a port hole channel 152 extending through the heat exchanger plates 100, 200. The port hole channel 152 is thus formed in the vertical direction V through the first heat exchanger plates 100 and the second heat exchanger plates 200 via the portholes 150. According to an embodiment, the port hole channel 152 may have a diameter of 3-50 mm. However, the diameter may preferably be, 4-30 mm, more preferably be 5-24 mm.

[0073]In FIG. 2, the plate package of the plate heat exchanger 10 has been separated through a second plate interspace 12. As best illustrated in FIG. 2, in a central area of each heat exchanger plate 100, 200 there is an active heat transfer area 180, which is provided with a corrugation 190 of ridges and valleys in a manner known per se. The heat transfer area 180 may of course have other kinds of patterns or even no pattern at all.

[0074]Now turning also to FIGS. 3A, 3B and 3C, here is conceptually depicted how the first heat exchanger plates 100 and the second heat exchanger plates 200 are shaped in proximity to the port hole channel 152 and how the port hole channel 152 is formed by the first heat exchanger plates 100 and the second heat exchanger plates 200. In FIGS. 3A, 3B and 3C, a major portion of the first heat exchanger plates 100 and the second heat exchanger plates 200 are not shown to more clearly illustrate how the respective heat exchanger plates 100, 200 are formed in proximity to the port hole channel 152. FIG. 3A, is a cross sectional view to through the port hole channel 152 over ten heat exchanger plates 100, 200. FIG. 3B illustrates a perspective view of FIG. 3A, but with slightly fewer heat exchanger plates 100, 200, whereas FIG. 3C illustrates an enlarged view of a portion of FIG. 3A. In the following, a relation between a first heat exchanger plate 100 and a second heat exchanger plate 200 will be described in greater detail. It is however to be understood that the description of the first heat exchanger plate 100 and the second heat exchanger plate 200 is equally valid for any first heat exchanger plate 100 and any adjacent second heat exchanger plate 200 of the plate heat exchanger 10.

[0075]As is illustrated in FIGS. 3A, 3B and 3C, and best seen in FIGS. 3A and 3C combined, a first heat exchanger plate 100 and a second heat exchanger plate 200 are joined via a first joining area A1. The first heat exchanger plate 100 and the second heat exchanger plate 200 are joined in a fluid tight manner via the first joining area A1. The first heat exchanger plate 100 and the second heat exchanger plate 200 may be joined in a fluid tight manner via the first joining area A1 by being brazed to each other.

[0076]As illustrated in FIGS. 3A, 3B and 3C, the first joining area A1 may be formed by joining a first horizontal section 108 of the first peripheral plate portion 102 with a first horizontal section 208 of the second peripheral plate portion 202. By the first joining area A1 being formed by joining a first horizontal section 108 of the first peripheral plate portion 102 with a first horizontal section 208 of the second peripheral plate portion 202, solder or braze material may be to advantage be applied by screen printing solder or braze material onto the first horizontal section 108 of the first peripheral plate portion 102 and/or onto the first horizontal section 208 of the second peripheral plate portion 202. In this way, the accuracy and overall quality of the brazing may be enhanced.

[0077]The first joining area A1 circumscribes the port hole channel 152 at a first radial distance R1 from a center C of the port hole channel 152. By this arrangement, a first peripheral plate portion 102 of the first heat exchanger plate 100 is formed. The first peripheral plate portion 102 extends between the first joining area A1 and the port hole channel 152. Correspondingly, a second peripheral plate portion 202 of the second heat exchanger plate 200 is formed. The second peripheral plate portion 202 extending between the first joining area A1 and the port hole channel 152.

[0078]As illustrated in FIGS. 3A, 3B and 3C, the first peripheral plate portion 102 and the second peripheral plate portion 202 circumscribes the port hole channel 152. In other words, the first peripheral plate portion 102 is the portion of the first heat exchanger plate 100 which is located between the first joining area A1 and the port hole channel 152. Correspondingly, the second peripheral plate portion 202 is the portion of the second heat exchanger plate 200 which is located between the first joining area A1 and the port hole channel 152. In this regard, it shall be noted that the first peripheral plate portion 102 and the second peripheral plate portion 202 generally, at least partly defines, the port hole channel 152. However, the first peripheral plate portion 102 and the second peripheral plate portion 202 must not take part in defining the port hole channel 152. As illustrated in FIGS. 3A, 3B and 3C, the first peripheral plate portion 102 and the second peripheral plate portion 202 are at least partially extending at a distance from each other in the horizontal direction H. In other words, the first peripheral plate portion 102 and the second peripheral plate portion 202 are shaped differently such that first peripheral plate portion 102 and the second peripheral plate portion 202 do not contact each other all the way between the first joining area A1 and the port hole channel 152.

[0079]As is illustrated in FIGS. 3A, 3B and 3C, and best seen in FIGS. 3A and 3C combined, a first section 104 of the first peripheral plate portion 102 extends towards the second peripheral plate portion 202 in the depicted plate heat exchanger 10. Correspondingly, a first section 204 of the second peripheral plate portion 202 extends towards the first peripheral plate portion 102 in the depicted plate heat exchanger 10. Hence, the first section 104 of the first peripheral plate portion 102 forms part of the first peripheral plate portion 102. Correspondingly, the first section 204 of the second peripheral plate portion 202 forms part of the second peripheral plate portion 202. More specifically, the first section 104 of the first peripheral plate portion 102 extends towards the second peripheral plate portion 202 and the first section 204 of the second peripheral plate portion 202 extends towards the first peripheral plate portion 102 at a second radial distance R2 from the center C of the port hole channel 152. In this way, a restricted volume V1 is formed between the first peripheral plate portion 102 and the second peripheral plate portion 202. The restricted volume V1 is hence located between the first radial distance R1 and the second radial distance R2, as illustrated in FIGS. 3A, 3B and 3C. The restricted volume V1 being in fluid communication with the port hole channel 152. The restricted volume V1 of as illustrated in FIGS. 3A, 3B and 3C, extends peripherally around the port hole channel 152 and has a general donut shape.

[0080]A first opening O1 may be provided between the restricted volume V1 and a first plate interspace 11. More than one first opening O1 may be provided between the restricted volume V1 and a first plate interspace 11. In the depicted embodiment of FIGS. 3A, 3B and 3C, two first openings O1 are provided between the restricted volume V1 and a first plate interspace 11. Such first opening O1 is generally referred to as a restriction hole O1 and is thus formed to provide the first fluid to the first plate interspaces 11. Any suitable number of first openings O1 may be used to advantage, such as 2, 3, 4, 5, 6, 7, 8, 9 or 10 first openings O1.

[0081]The first opening or openings O1 may according to an embodiment have a cross sectional area of 0.1-1.0 mm². The cross-sectional area may according to an embodiment preferably be 0.25-0.55 mm², more preferably be 0.35-0.45 mm². The first opening may in this regard be a circular hole provided in the second peripheral plate portion 202 as illustrated in FIGS. 3A, 3B and 3C. However, the first opening O1 may have any suitable shape other than the circular shape. The first opening O1 may be oblong, oval or elliptic.

[0082]In the depicted embodiment of FIGS. 3A, 3B and 3C, the first section 104 of the first peripheral plate portion 102 and the first section 204 of the second peripheral plate portion 202 meets and are joined in a fluid tight manner at the second radial distance R2. Hence, the first section 104 of the first peripheral plate portion 102 and the first section 204 of the second peripheral plate portion 202 are joined via a second joining area A2 which is located at the second radial distance R2. Hence, the second joining area A2 is located closer to the center of the port hole channel 152 than the first joining area A1.

[0083]As illustrated in FIGS. 3A, 3B and 3C, the second joining area A2 may be formed by joining a second horizontal section 110 of the first peripheral plate portion 102 with a second horizontal section 210 of the second peripheral plate portion 202. By the second joining area A2 being formed by joining a second horizontal section 110 of the first peripheral plate portion 102 with a second horizontal section 210 of the second peripheral plate portion 202, solder or braze material may be to advantage be applied by screen printing solder or braze material onto the second horizontal section 110 of the first peripheral plate portion 102 and/or onto the second horizontal section 210 of the second peripheral plate portion 202. In this way, the accuracy and overall quality of the brazing may be enhanced.

[0084]The second joining area A2 may comprise a discontinuance O2 providing for said fluid communication between the port hole channel 152 and the restricted volume V1. The discontinuance O2 may form a second opening O2 between the port hole channel 152 and the restricted volume V1 thereby providing for the fluid communication. In the depicted embodiment of FIGS. 3A, 3B and 3C, the second joining area A2 comprises two discontinuances O2. The two discontinuances O2 forming a respective second opening O2 between the port hole channel 152 and the restricted volume V1.

[0085]In the depicted embodiment of FIGS. 3A, 3B and 3C, a first opening O1 and a second opening O2 extend along a common radial direction whereas the other first opening O1 and a the other second opening O2 extend along a different common radial direction. However, it is to be understood that a first opening O1 and a second opening O2 may extend different radial directions. Further, any suitable number of second openings O2 may be used to advantage, such as 2, 3, 4, 5, 6, 7, 8, 9 or 10 second openings O2.

[0086]The second opening or openings O2 may be formed by a notch N in the first peripheral plate portion 102 at the second joining area A2. The second opening or openings O2 may formed by a notch N in the first peripheral plate portion 102 at the second joining area A2. The second opening or openings O2 may be formed by a notch N in the first peripheral plate portion 102 at the second joining area A2 and/or in the second peripheral plate portion 202 at the second joining area A2. In the depicted embodiment of FIGS. 3A, 3B and 3C, the second openings O2 are formed by notches N, N pressed in the first heat exchanger plate 100 and in the second heat exchanger plate 200 respectively. Such notches N, N may to advantage be formed when forming the heat exchanger plates 100, 200.

[0087]The second opening O2 may according to an embodiment have a cross sectional area of 1-15 mm². The cross-sectional area may according to an embodiment preferably be 1.5-10 mm², more preferably 2-5 mm². Hence, the cross-sectional area of the second opening O2 may be larger than the cross-sectional area of the first opening O1. The cross-sectional area of the second opening O2 may be about 10-15 times larger than the cross-sectional area of the first opening O1.

[0088]By the cross-sectional area of the second opening O2 being larger than the cross-sectional area of the first opening O1, an efficient distribution and/or mixing of liquid and vapor of the first fluid may be achieved with a limited or no pressure drop as compared to prior art solutions where a restriction hole is provided directly from a port hole channel to e.g., a first plate interspace.

[0089]In the depicted embodiment of FIGS. 3A, 3B and 3C, the first peripheral plate portion 102 further comprises a first end section 106. The first peripheral plate portion 102 is thus partially formed of the first end section 106. As best seen in FIG. 3C, the first end section 106 is partially defining the port hole channel 152. Further, the first end section 106 extends substantially along the vertical direction V. In the depicted embodiment of FIGS. 3A, 3B and 3C, a major portion of the first end section 106 is aligned with and extends along the extension of the port hole channel 152.

[0090]Further, in the depicted embodiment of FIGS. 3A, 3B and 3C, the second peripheral plate portion 202 further comprises a second end section 206. The second peripheral plate portion 202 is thus partially formed of the second end section 206. As best seen in FIG. 3C, the second end section 206 is partially defining the port hole channel 152. Further, the second end section 206 extends substantially in a direction opposite to the vertical direction V. In the depicted embodiment of FIGS. 3A, 3B and 3C, a major portion of the second end section 206 is aligned with and extends along the extension of the port hole channel 152.

[0091]The first end section 106 and the second end section 206 are typically formed by being pressed when forming the first and second heat exchanger plates 100, 200. As best seen in FIGS. 3A and 3C, the first end section 106 and the second end section 206 may define or form the port hole channel 152. In the depicted embodiment of FIGS. 3A, 3B and 3C, the port hole channel 152 is configured to receive the first fluid in a direction opposite to the vertical direction V. Flow of the first fluid form the port hole channel 152, into a restricted volume V1 and further into a first plate interspace 11 is schematically in indicated by a set of hatched arrows in FIG. 3A.

[0092]Further, As best seen in FIGS. 3A and 3C, the first end section 106 and the second end section 206 may define or form dead volume V2. The dead volume V2 is dead in the sense that it may only communicate with the port hole channel 152. Hence, the dead volume V2 is not connected to the first plate interspaces 11 or the second plate interspaces 12. In other words, any fluid entering into the dead volume V2 may only be fed back to the port hole channel 152.

[0093]In the depicted embodiment of FIGS. 3A, 3B and 3C, the vertical extension of the first end section 106 is equal to a vertical extension of the second end section 206. Hence, the first end section 106 extends a distance along the port hole channel 152 which is equal to a distance over which the second end section 206 extends along the port hole channel 152. In this regard, it shall be noted that the first end section 106 extends substantially in the vertical direction V whereas the second end section 206 extends in a direction substantially opposite to the vertical direction V.

[0094]However, according to embodiments, the vertical extension of the first end section 106 may be smaller than the vertical extension of the second end section 206 or vice versa.

[0095]In the depicted embodiment of FIGS. 3A, 3B and 3C, the first end section 106 and second end section 206 are provided at the same radial distance from the center C the port hole channel 152. Hence, the outer end of the first end section 106 meets the outer end of the second end section 206 as best seen in the lower part of FIG. 3C.

[0096]Now also turning to FIG. 4. FIG. 4. Illustrates an embodiment which is similar to the embodiment described above in conjunction with FIGS. 3A, 3B and 3C. Therefore, in the following, only differences in relation to the embodiment of FIGS. 3A, 3B and 3C will be described to avoid undue repetition. As illustrated in FIGS. 4, and 2, a circumferential extension of the restricted volume V1 may be delimited by a pair of protrusions P1, P2. Hence, the otherwise generally donut shaped restricted volume V1 may be restricted to only extend along a portion of the circumference of the port hole channel 152 rather than along the complete circumference of the port hole channel 152 as in FIGS. 3A, 3B and 3C. As illustrated in FIGS. 4, and 2, a pair of restricted volumes V1 are formed between a respective pair of protrusions P1, P2. Each one of the restricted volumes V1 of FIGS. 4 and 2 extends along a portion of the circumference of the port hole channel 152.

[0097]The protrusions P1, P2 may be provided in the first peripheral plate portion 102 and in the second peripheral plate portion 202. Alternatively, the protrusions P1, P2 may be provided in the first peripheral plate portion 102 or in the second peripheral plate portion 202. As illustrated in FIGS. 4, and 2, the protrusions P1, P2 may extend radially between the first joining area A1 and the second joining area A2.

[0098]Now also turning to FIG. 5. FIG. 5. Illustrates an embodiment which is similar to the embodiment described above in conjunction with FIGS. 3A, 3B and 3C. Therefore, in the following, only differences in relation to the embodiment of FIGS. 3A, 3B and 3C will be described to avoid undue repetition. In the heat exchanger 10 of FIG. 5, the first end section 106 is provided at a larger radial distance from the center C of the port hole channel 152 than the second end section 206. Further, the first end section 106 and the second end section 206 overlap each other. This means that the port hole channel 152 is to a greater extent defined by the second end section 206 than the first end section 106. Further, the overlap of the first end section 106 and the second end section 206 allows for that the first fluid may easily flow into the port hole channel 152 in a direction opposite to the vertical direction V. This is because the first end section 106 and the second end section 206 overlap like fish scales, hence promoting a flow of the first fluid along the port hole channel in a direction opposite to the vertical direction V.

[0099]Protrusions P1, P2 of the type described above in conjunction with FIGS. 4 and 2 may to advantage be combined with the embodiment of FIG. 5.

[0100]Now also turning to FIG. 6. FIG. 6. Illustrates an embodiment which is similar to the embodiment described above in conjunction with FIGS. 3A, 3B and 3C. Therefore, in the following, only differences in relation to the embodiment of FIGS. 3A, 3B and 3C will be described to avoid undue repetition. In the heat exchanger 10 of FIG. 6, the first end section 106 and the second end section 206 are generally speaking provided at the same radial distance from the center C of the port hole channel 152 like in the embodiment of FIGS. 3A, 3B and 3C. However, the first end section 106 and the second end section 206 are extending in slightly different directions as compared to the first end section 106 and the second end section 206 of the embodiment of FIGS. 3A, 3B and 3C. in practice, the first end section 106 and the second end section 206 has been bent slightly more such that the outer end of the first end section 106 meets the outer end of the second end section 206 at a slightly larger radial distance from the center C of the port hole channel 152 than a mean radial distance of first end section 106 and the second end section 206 the from the center C of the port hole channel 152. By the above design of FIG. 6 of the first end section 106 and the second end section 206, the interior of the port hole channel 152 becomes more irregular with periodically varying diameters along its extension as compared to the port hole channel 152 of the embodiment of FIGS. 3A, 3B and 3C.

[0101]Protrusions P1, P2 of the type described above in conjunction with FIGS. 4 and 2 may to advantage be combined with the embodiment of FIG. 6.

[0102]Now also turning to FIG. 7. FIG. 7. Illustrates an embodiment which is similar to the embodiment described above in conjunction with FIGS. 3A, 3B and 3C. Therefore, in the following, only differences in relation to the embodiment of FIGS. 3A, 3B and 3C will be described to avoid undue repetition. In the heat exchanger 10 of FIG. 7, the first end section 106 is omitted. This means that the first peripheral plate portion terminates at the second joining area A2 as illustrated in FIG. 7. The second end section 206 on the other hand has a larger extension along the port hole channel 152 as compared to the embodiment of FIGS. 3A, 3B and 3C. The second end section 206 of the embodiment of FIG. 7 extends substantially in a direction opposite to the vertical direction, i.e., like the second end section 206 of the embodiment of FIGS. 3A, 3B and 3C. The omission of the first end section 106 results in that the port hole channel 152 of the embodiment of FIG. 7 is substantially defined by the second end sections 206.

[0103]Further, the extension of the second end section 206 allows for that the first fluid may easily flow into the port hole channel 152 in a direction opposite to the vertical direction V. This is because the second end section 206 to some degree resembles fish scales, hence promoting a flow of the first fluid along the port hole channel in a direction opposite to the vertical direction V.

[0104]Protrusions P1, P2 of the type described above in conjunction with FIGS. 4 and 2 may to advantage be combined with the embodiment of FIG. 7.

[0105]Now also turning to FIG. 8. FIG. 8. Illustrates an embodiment which is similar to the embodiment described above in conjunction with FIGS. 3A, 3B and 3C. Therefore, in the following, only differences in relation to the embodiment of FIGS. 3A, 3B and 3C will be described to avoid undue repetition. Like in the embodiment of FIGS. 3A, 3B and 3C, the a first heat exchanger plate 100 and a second heat exchanger plate 200 are joined in a fluid thigh manner via a first joining area A1. The first joining area A1 circumscribes the port hole channel 152 at a first radial distance R1 from a center C of the port hole channel 152 thereby forming a first peripheral plate portion 102 of the first heat exchanger plate 100 extending between the first joining area A1 and the port hole channel 152. Correspondingly, a second peripheral plate portion 202 of the second heat exchanger plate 200 extending between the first joining area A1 and the port hole channel 152 is formed. The first peripheral plate portion 102 and the second peripheral plate portion 202 circumscribes the port hole channel 152 and are at least partially extending at a distance from each other in the horizontal direction H.

[0106]Like in the embodiment of FIGS. 3A, 3B and 3C a first section 104 of the first peripheral plate portion 102 extends towards the second peripheral plate portion 202 at a second radial distance R2 from the center C of the port hole channel 152 thereby forming the restricted volume V1 between the first peripheral plate portion 102 and the second peripheral plate portion 202 between the first radial distance R1 and the second radial distance R2. The restricted volume V1 of FIG. 8 is in fluid communication with the port hole channel 152.

[0107]This means in practice that each port hole 150 is surrounded by a peripheral inner rim 15 formed by a portion of the first section 104 of the first peripheral plate portion 102. Hence, the peripheral rim 15 is annular and extends substantially transversally to the extension plane P.

[0108]The peripheral inner rim 15 is surrounded by a peripheral outer rim 13 formed by a portion of the second peripheral plate portion 202. The peripheral outer rim 13 having a top end 16 and a root end 17. The peripheral outer rim 13 has a rim height H perpendicular to the extension plane P from the root end 17 to the top end 16. Substantially parallel to the outer rim 13 is the inner rim 15 arranged. The inner rim 15 has a rim height h perpendicular to the extension plane P. The inner rim height h is shorter than the outer rim height H, which results in an opening 14 being defined between the lower end point of the inner rim 15 and the root end 17. In other words, the restricted volume V1 is formed between the first peripheral plate portion 102 and the second peripheral plate portion 202 between the first radial distance R1 and the second radial distance R2. The restricted volume V1 of FIG. 8 is in fluid communication with the port hole channel 152 via the opening 14. The opening 14 of FIG. 8 is thus a slit circumscribing the port hole channel 152.

[0109]The relation between the inner rim height h and the outer rim height H, h/H may be 75%, 80%, 85%, 90% or 95%.

[0110]The relation of the inner rim height h and the outer rim height H, h/H, may be at least 80%.

[0111]The relation of the inner rim height h and the outer rim height H, h/H, may be at least 90%.

[0112]In the embodiment of FIG. 8, each of the second heat exchanger plates 200 also comprises at least one first opening O1 in form of a restriction hole O1, which extends through the peripheral outer rim 13. It should be noted that each peripheral outer rim 13 may be provided with one or more first openings O1.

[0113]The first opening O1 or restriction hole O1 forms a fluid passage for the first fluid from the port hole channel 152 to the first plate interspaces 11.

[0114]The first opening O1 or restriction hole O1 may be circular, oval, or may have any other shape, seen from the restricted volume V1. Especially, in the embodiment of FIG. 8, the first opening O1 may have an oval or other elongated shape, wherein the elongated shape extends in parallel to the extension plane P to maximize the distance to the root end 17 and the top end 16.

[0115]The first opening O1 or restriction hole O1 may be premade before the heat exchanger plates 100, 200 are assembled and joined to each other to form the plate heat exchanger 10.

[0116]More specifically, the first opening O1 or restriction hole O1 may be centrally located between the root end 17 and the top end 16 of the peripheral rim. The restriction hole 10 is thus located at the same distance from the root end 17 and the top end 16.

[0117]The diameter of the first opening O1 or restriction hole O1 may be maximum 15 mm.

[0118]The heat exchanger 10 of FIG. 8 may generally be manufactured by the following manufacturing steps.

[0119]The first heat exchanger plates 100 may be provided with a peripheral inner rim 15 around the port hole channel 152, wherein the peripheral inner rim 15 initially extends in parallel with the extension plane P.

[0120]The peripheral inner rim 15 may then bent to extend transversely to the extension plane P from the top end 16 towards a root end 17 with an inner rim height h perpendicular to the extension plane P.

[0121]The first opening O1 or restriction hole O1 may be made through the peripheral outer rim 13 by any suitable hole-making method, such as drilling, laser beam cutting, electron beam cutting, etc. It is to be noted that the restriction hole O1 may be made before or after bending of the peripheral rim 13.

[0122]Thereafter, the first and second heat exchanger plates 100, 200 may be stacked in an alternating fashion with braze material between adjacent first and second heat exchanger plates 100, 200.

[0123]The first heat exchanger plates 100, the second heat exchanger plates 200 and the braze material may be heated to melt the braze material. The melted braze material may be attracted by areas where the first and second heat exchanger plates 100, 200 are close to or adjoining each other. After active or passive cooling, the heat exchanger plates 100, 200 are joined to each other via joints of braze material between the first and second heat exchanger plates 100, 200.

[0124]From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways.

[0125]For instance, when the plate heat exchanger 10 is to be brazed for joining the heat exchanger plates 100, 200 to each other, the braze material may be provided in the form of foils, instead of being screen printed. The foils are then introduced between adjacent first and second heat exchanger plates 100, 200. During the brazing, the braze material is molten and will flow to the joints which will join the heat exchanger plates 100, 200 to each other.

[0126]Further, the disclosure is also applicable to plate heat exchangers 10 having another number of portholes than four, for instance six portholes. The plate heat exchanger 10 may then comprise primary first plate interspaces for a primary first fluid to be evaporated, secondary first plate interspaces for a secondary first fluid to be evaporated, and second plate interspaces for a second fluid to heat, or possibly cool, the primary and secondary first fluids. There are then two inlet channels leading to the primary first plate interspace and the secondary first plate interspaces, respectively. Each second plate interspace may typically be adjacent to a primary first interspace and a secondary first plate interspace.

[0127]It will be appreciated that the present inventive concept is not limited to the variants and examples shown. Several modifications and variations are thus conceivable within the scope of the invention which thus is defined by the appended claims.