Patent Application
20240118042
The present application claims priority to European Application Serial No. EP22382929.2, filed on Oct. 5, 2022, the disclosure of which is hereby incorporated by reference herein.
The present description relates to a flat heat exchanger of the types which use a single working fluid circulating continuously through the inside of one or a plurality of heat transmission conduits for cooling one or more electric or electronic elements or components or the like located in a position close to or in contact with a region of the outer part of at least one heat transmission conduit.
In recent years, one of the most intensively developed fields of the art is the field of electric or hybrid vehicles, and accordingly also of their different components.
Different types of power electronic components suitable for being installed in electric or hybrid vehicles, such as semiconductor devices intended for switching, amplifiers, power switches, or in DC-DC converters, on-board chargers, etc., require systems for cooling them. It is known that temperature negatively affects component service life and the temperature of the component must be controlled such that it falls within specific temperature ranges. Given the increasing miniaturization of electronic elements or components, elements of this type require heat to be discharged into very small areas which, however, lead to the generation of a lot of heat. This is the case of switching devices used for powering resistors or IGTBs used in inverters with high switching rates.
Semiconductor devices are usually protected by a casing or embedded in a plastic body.
Heat is usually discharged from the outer surface of the casing or of the protective body.
Similarly, systems are required for cooling the batteries of electric or hybrid vehicles. It is known that battery temperature is the key factor in battery life, performance, and safety. For example, the performance of lithium-ion batteries depends greatly on their operating temperature and said batteries do not work correctly when they are subjected to too high or too low temperatures. For this reason, electric vehicle manufacturers and suppliers seek to improve battery thermal management systems in order to control the temperature of battery cells such that it falls within the safe and efficient established limits which cool or heat said cells, where necessary, and to achieve a battery service life that is at least as long as the service life of the vehicle in which the battery is installed.
In this regard, electric or hybrid vehicles typically use cooling systems for cooling certain power electronic components or battery cells.
Different thermal management systems for said power electronic components or batteries are available on the market: active and passive thermal management systems which can in turn be classified by different concepts.
First, they are classified by the purpose of the thermal management system: heating, cooling, or both. Second, they are classified by the means used to achieve said purpose, which can be air or liquid. Lastly, they are classified by the source used for thermal control. The system is a passive thermal management system if the liquid or air introduced into the battery compartment enters said compartment without prior additional preconditioning and it is an active thermal management system if a specific temperature-control component is installed previously.
Active thermal management systems for said power electronic components or batteries are generally based on the forced circulation of specific substances such as water and air around the battery or the external component with which heat exchange is to be performed.
This invention focuses on active cooling systems, wherein the heat exchange fluid is typically a liquid coolant, and wherein the liquid coolant can be, for example: a natural coolant such as water, or a mixture of water and an organic substance-based antifreeze, such as ethylene glycol.
In general, the concept of a heat exchanger is a device used for forcing the exchange of energy, in the form of heat, between at least two heat sources at different temperatures, typically two fluids. However, heat exchangers referred to in this invention comprise a structure designed to establish a thermal communication between a single heat transmission fluid, which flows continuously in a confined manner through the inside of at least one conduit of the heat exchanger, and an external element or component arranged outside of, but in thermal contact with, the heat exchange conduit. In this way, heat transmission occurs through physical walls separating the heat transmission fluid from the external element or component, i.e., through one or more walls of the conduit(s), depending on whether the component is in contact with only one conduit or interposed between two different conduits.
One of the heat exchangers conventionally used in the field of the active cooling of power electronic components or batteries that are, for example, suitable for being installed in electric or hybrid vehicles is the flat heat exchanger. The flat heat exchanger is typically made up of one or a plurality of heat exchange conduits through which a heat transmission fluid flows continuously, said fluid being capable of cooling one or more electric or electronic elements or components or similar external electric or electronic elements or components, with said electric or electronic elements or components being located in a position close to or in close thermal contact with the outer part of the heat transmission conduit(s).
In this way, the heat transmission fluid transmits or receives heat through the material of the conduit (generally a metal wall), separating the heat transmission fluid from the external physical element(s) or component(s), thereby forcing convection through the heat transmission fluid (which is generally at a lower temperature than the external element(s) or component(s)) and heat conduction through the material of the conduit walls from the external element(s) or component(s) (which generally is/are at a higher temperature than the heat transmission fluid).
However, heat exchange in the heat exchanger of the present invention is not aimed solely at cooling one or more external electric or electronic elements or components, arranged in specific positions in the outer part of the heat exchanger, but also can be used for cooling, or even heating, an object or element arranged in a specific external position with respect to the flow passage conduit(s), which are not strictly a power electronic component or a battery for an electric or hybrid vehicle.
A known configuration of a flat heat exchanger for such purpose is formed by one or a plurality of flow passage conduits (which will be referred to herein interchangeably as flow passage conduits or heat exchange conduits) for interposing one or more elements to be cooled between the plurality of conduits arranged in a stack. With this configuration, both sides of the conduit contribute to heat transfer, and heat dissipation thereby increases.
Flat heat exchangers which, for the purpose of improving heat exchange performance, have on the inside of each heat exchange conduit, an intermediate flat plate-like partitioning element, are known, said partitioning element forming a middle flow path through which the heat exchange flow flows into a two-stage enveloping heat exchange conduit in the direction of the thickness of the heat exchange tube in the shape of a flat cross-section.
Furthermore, an inner fin is arranged in each of the fluid flow paths formed in the two stages. The use of inner fins in exchangers of this type to create turbulences in the passage of the coolant fluid in the flow direction, and accordingly to increase heat extraction from the fluid through the walls, is known. In this known configuration, the enveloping heat exchange conduit can be configured by two covers with a shape such that they constitute an enveloping flow passage tub, inside which an inner fin is arranged in each of the two stages.
The elements constituting the heat exchanger are generally manufactured from a metal material having a high thermal conductivity, such as aluminum, copper, or alloys thereof. Furthermore, the members constituting the heat exchanger are generally attached by means of brazing, being heated in a heating oven after being combined with one another in the heat exchanger manufacturing process.
The inner fin, also known as turbulator, is typically configured as a compact element of little thickness, extending along the flow direction. It has a width slightly smaller than the width of the flow conduit and a length smaller than the length of the flow conduit so that it can fit inside the conduit. The turbulator may have different configurations for the purpose of increasing heat transmission from the external element to be cooled to the coolant fluid. One possible way is to design one or more channels extending in a wavy manner along the flow direction, such that it forms one or a plurality of wavy paths, in which the heat exchange fluid meanders and flows along said divided paths. There may be other intersection elements in the turbulator for modifying the flow inside the conduit by increasing fluid turbulence.
An objective sought by flat heat exchangers is to minimize, as much as possible, the pressure drop of the coolant fluid during its passage through the inside of the heat transmission conduit, to thereby maximize the efficiency of heat transfer with the external element(s) or component(s). In the state of the art, it is considered that where there is no heat exchange with an external element or component to be cooled, what is sought is that there is no pressure drop in the heat transmission fluid.
Pressure drop in a pipe or conduit is the pressure drop that occurs in a fluid due to the fluid particles brushing against one another and against the walls of the conduit guiding the fluid. Therefore, one skilled in the art knows that, in order to minimize the pressure drop in the heat transmission fluid along the inside of the conduit, there is a need to avoid interposing any type of element which may somehow disrupt or block fluid flow in the flow direction, for example, any element which generates a limit layer generating an entrainment effect causing the pressure drop. For said reason, in the specific locations or segments of the turbulators where there is no external element or component to be cooled nearby, no element or obstacle (such as a fin or any other type of disrupting element) which may intersect the flow path is provided, with the path for fluid flow in that specific segment thereby being left completely free of any obstacle.
Pressure drop has a negative influence on the performance of the heat exchanger since it directly affects the flow rate of the coolant flow which is capable of circulating therethrough and increases the energy cost required for driving the movement of the liquid coolant. The coolant flow rate is proportional to the heat energy discharged in the heat exchanger, so an increase in pressure drop directly affects the reduction of the heat exchanged.
The second problem identified in the state of the art associated with flat heat exchangers of this type is that since they have little thickness and a certain length extending along the flow direction, they must have sufficient flexural rigidity, i.e., sufficient flexural strength. In those cases in which sufficient rigidity is not achieved, the heat exchanger may experience excessive deformation or may even break, particularly during its manufacturing or assembly phase. In the particular case of an exchanger with a turbulator provided with segments with non-straight fins, wherein two segments with non-straight fins are intercalated with an empty segment without fins, the coefficient of rigidity thereof cannot reach the required values. Therefore, there is a need to design an improved heat exchanger with a turbulator, and wherein the heat exchanger has a coefficient of rigidity, mainly flexural rigidity, that is sufficient for such uses.
The main problem that this invention seeks to sole is to provide a flat heat exchanger, formed by one or more heat transmission conduits through the inside of which a coolant fluid circulates continuously, said coolant fluid being capable of cooling one or more electric or electronic elements or components or the like located in a position close to the external part of the heat transmission conduit(s), such that this coolant fluid exchanges heat through the wall of the conduit separating the fluid from the physical external component(s), thereby forcing heat convection and conduction from the external component(s) (generally at a higher temperature) to the fluid (generally at a lower temperature) and with the particularity that the heat exchanger has a lower pressure drop compared to other heat exchangers existing today, and at the same time, without the thermal resistance worsening.
The present invention provides a solution to the problems mentioned above, by means of a heat exchanger, preferably a flat heat exchanger, according to claim 1, which uses a single heat exchange fluid for cooling or heating one or more external elements or components with respect to the heat exchanger, wherein said one or more external elements or components are arranged close to or in contact with a region of the outer surface of one or more fluid exchange conduits of the heat exchanger through which the heat exchange fluid flows. The dependent claims define preferred embodiments of the invention.
In a first inventive aspect, the invention provides a heat exchanger comprising:
In this application, the term “external element or component” is understood to mean any element or component or device which is external with respect to the heat exchanger of the invention, and arranged and configured for being cooled preferably by the heat exchanger, since the external element or component is at a higher temperature than the coolant fluid in the heat exchanger. It is also understood that the “external element or component” is arranged close to or in contact with a region of the outer heat exchange surface of one or more conduits of the heat exchanger through which the coolant fluid flows. Preferably, said external element or component is a heat source, a battery cell, or an electric or electronic component to be cooled, although it could be a similar element. However, in some specific cases, such as in “cold-plates” of batteries, where the aim is to enable both cooling and heating the cell with the same heat exchanger depending on needs, the heat exchanger of the invention can also be arranged and configured for heating the external element(s) or component(s).
In this application, the term “being in thermal contact with” is understood to mean being in a close physical position or in close contact, such that heat conduction is established between the elements that are in thermal contact. For example, an intermediate element or substance may be arranged between the outer surface of the heat transfer conduit and the external element or component to be cooled, such that the thermal contact between both does not have to be a direct contact between the elements, but rather with the intermediation of another element or substance which does not interrupt heat conduction between the elements or can even favor same.
In this application, the term “turbulator” or “inner fin” is understood, interchangeably, to mean a component which causes increased heat exchange by enhancing the coefficient of heat exchange through convection caused by an increase in the contact area with the coolant fluid, leading in some cases to turbulence. Examples of turbulator elements are fins, permeable foams, protrusions emerging from the surface of the conduit directing the flow, etc. In the preferred examples of the invention, the “turbulator” element is formed by a set of sheet-like fins. More specifically, the described examples will use of a set of sheet-like fins where the sheet is folded forming passage channels for the fluid.
In this application, the term “coolant fluid” is understood to mean a liquid intended for exchanging heat by convection with an exchange surface and transporting it to favor the cooling or heating of the surface. In particular, the liquid coolant can be water mixed with an ethylene glycol-based antifreeze, or water mixed with an organic substance such as ammonia, or a natural coolant such as water. The term “coolant” should not be interpreted as limiting the function of the heat exchanger to cooling one or more external elements or components, given that, in some specific cases of the invention, the fluid can work to heat the external component(s). Therefore, the term “coolant fluid” in the present application should be interpreted as a “heat exchange fluid” suitable for exchanging heat (cooling or heating) with one or more external elements or components with respect to the heat exchanger which are at a temperature different from the fluid temperature.
In this application, the term “thermal footprint region” is understood to mean an inner surface of the heat exchange wall defined by the projection of the region configured to be in thermal contact with at least one external element or component with respect to the exchanger that is to be cooled or heated, i.e., the projection defined according to a direction perpendicular to the exchange wall where the heat exchange region is located. Accordingly, there may be a single external element or component with respect to the exchanger that is to be cooled or heated or more than one external element or component in the same thermal footprint region. If there is more than one external element or component close to one another comprised in a thermal footprint region, it is understood that this thermal footprint region corresponds to the perimeter of the minimum rectangle containing therein neighboring external elements or components forming a group.
It is understood that two or more external heat-generating elements or components form a group when their distances from one another are smaller than the distances between the minimum rectangles contained in each group.
The particular design of the at least one turbulator of the heat exchanger of the invention with a configuration such that, where no external element or component is nearby, such as a heat source, there is envisaged a segment with fins formed by one or more straight fins generating segments of flow channels which follow a rectilinear path in the flow direction, and wherein said flow channels of the segment with straight fins being connected continuously (i.e., without discontinuities) along the flow direction with the corresponding adjacent flow channels of a segment with non-straight fins of the same turbulator provides several advantages over existing heat exchangers, as set forth by applicant.
First, the applicant has observed empirically that the attachment or connection of segments having non-straight channels by means of straight channels gives rise to a guided fluid flow which advantageously reduces the pressure drop of the fluid in the areas where a high cooling performance is not required, despite of the establishment of additional surfaces which cause a flow entrainment effect.
In that sense, with this new design of the heat exchanger of the invention, contrary to what was expected, a lower pressure drop is obtained compared to that which would be obtained if no fin were arranged between the segments of curved conduits and the section of the conduit were free. In other words, the invention allows achieving a reduction of pressure drop with respect to other type of heat exchanger, and also a thermal performance similar to the performance of conventional heat exchangers with wavy fins, wherein these segments with wavy fins are located only in the thermal footprint regions. In that sense, an optimal cooling performance and improved behavior in the pressure drop of the coolant fluid are obtained with the heat exchanger of the invention.
Second, the applicant has demonstrated that by arranging in the heat exchanger of the invention a turbulator having one or more segments with straight channels connecting consecutive segments with non-straight channels, the rigidity, mainly the flexural rigidity, of the heat exchanger is increased. In other words, an exchanger with a continuous turbulator, formed by the intercalation of segments with straight and non-straight fins, as proposed in the present invention, is more rigid compared to a heat exchanger with a conventional turbulator formed by a series of segments with non-straight fin separated from one another by a respective empty segment. In this application, an “empty segment” is understood to mean a segment of the turbulator without any fin.
Third, the applicant has demonstrated that, in some cases, the heat exchanger of the invention is more resistant to pressure fatigue.
As defined above, the at least one turbulator in the heat exchanger of the invention has at least one segment with fins which are not straight and at least one segment with fins which are straight. Segment(s) with non-straight fins are more efficient in heat exchange compared to segment(s) with straight fins, hence it is the configuration used in the thermal footprint region for the purpose of exchanging the largest possible amount of heat with the coolant fluid.
In this application, when the term “segment with non-straight fins” is described for the turbulator, it should be interpreted to mean that the fins in that area are configured such that the coolant fluid follows a non-straight path. For example, if a type of non-straight fins of the type which are offset in the flow direction is selected, the different segments forming the fin are straight but the path the fluid follows is not straight, because it hits against the edge of the walls (since the segments with fin are offset transversely) and this generates turbulence.
Preferably, at least one segment with non-straight fins of a turbulator of the heat exchanger of the invention is a segment with fins selected from one of the following types: (a) wavy fins in the flow direction with a triangular profile or rounded profile (such as a square wave with rounded corners or a sine wave), or (b) fins offset in the flow direction. Preferably, in the case where the segment with non-straight fins is a segment with fins of a wavy type in the flow direction, the non-straight fin is in the shape of a wave with a channel-shaped cross-section substantially in the sine sector. Preferably, all the different segments with non-straight fins forming the turbulator of the heat exchanger of the invention are a segment with fins selected from types “a” or “b” described above. Preferably, all the different segments with non-straight fins forming the turbulator of the heat exchanger of the invention are of the same type of fins.
In this application, a type of segments with fins “offset” in the flow direction is understood to mean a fin made up of different straight segments arranged along the flow direction. The axis of the even-numbered segments is offset in the transverse direction by a certain distance with respect to the axis of the odd-numbered segments.
In the first case “a” of a segment with wavy fins, the different segments making up the fin have an orientation following a non-straight path (specifically a wavy path in the longitudinal direction of the flow), such that the path of the fluid going through said fins meanders following said wavy paths. Furthermore, in the second case “b” of a segment with offset fins, the different segments making up the fin are straight, but the path of the fluid is not straight, because it hits against the edge of the walls of the fin (since the segments with fin are offset transversely).
In this application, when the term “segments with straight fins” is described for the turbulator, it should be interpreted to mean that the fins in that area have an orientation following a straight line according to the substantially longitudinal direction of the turbulator, i.e., the flow of the fluid passing through said segment with straight fins follows a rectilinear path in the longitudinal direction of the turbulator.
Preferably, the turbulator of the heat exchanger of the invention can have more than one segment with fins which are not straight and more than one segment with fins which are straight, wherein a segment with fins which are not straight is intercalated with a segment with fins which are straight. The number of different segments with fins of a turbulator according to the exchanger of the present invention can be any number equal to or greater than two (at least one segment with straight fins adjacent to a segment with non-straight fins), depending on the number of the element to be cooled (for example, an external heat source) by each heat exchanger model. By way of example, the following configurations of turbulators formed by different number of segments with fins are possible:
In this application, the term “heat exchange conduit” is understood to mean any possible configuration of a tube, conduit, or chamber, provided with walls forming an enclosure or inner hollow volume through which the heat exchange fluid can circulate in a confined manner along a direction, identified as the flow direction.
All the examples that will be described below use flat conduits, that is, conduits formed by two flat walls, a first wall corresponding to the heat exchange wall, a second wall spaced from the first wall, and side walls connecting the first and second walls. In some embodiments of the present invention, said second wall also exchanges heat. The conduit houses the turbulator which is also flat and has the thickness determined, or at least demarcated by, the separation between the surfaces of the flat walls of the conduit housing it. In this context, the term “thickness of the turbulator” is understood as the distance between these two surfaces of the flat walls of the conduit limiting it.
Preferably, the flat turbulator has thermal contact with at least one of the flat walls of the conduit housing it, for example by means of brazing.
The heat exchange wall according to these embodiments is one of the flat walls.
In the examples which will be described below, the channels of the segments with non-straight fins follow a winding path contained in a plane parallel to the flat surfaces demarcating the turbulator. According to a preferred embodiment, the winding path of the channels of the segments with non-straight fins is sinusoidal.
The flow channels established by the non-straight fin configuration present continuity with the flow channels established by the straight fin configuration, such that both segments are adjacent to one another. Continuity in the flow channels does not mean that there is continuity in the derivative of the path of the channels, although it is desirable.
Preferably, between a segment with non-straight fins and an adjacent segment with straight fins of the at least one turbulator of the heat exchanger of the present invention there is no intermediate connection segment between segments, such that the connection between one end of a segment with straight fins and one end of an adjacent segment with non-straight fins is direct. However, in a particular embodiment of the invention, between a segment with non-straight fins and an adjacent segment with straight fins, it is possible to have an intermediate connecting segment between two segments with fins, for example, for the purpose of adapting the winding path of the non-straight fins to the straight fins.
Likewise, it is established that the segment with non-straight fins of the at least one turbulator of the heat exchanger of the present invention comprises mainly a thermal footprint region, where the term “mainly” should be interpreted to mean that most of the thermal footprint region is inside the area covered by the segment with non-straight fins. The same occurs with the segment with straight fins, this segment comprises mainly a region outside the thermal footprint region, where the term “mainly” should be interpreted to mean that most of the area covered by the segment with straight fins is outside the thermal footprint region.
Therefore, in accordance with the preceding paragraph, it is possible for the segment with non-straight fins of the at least one turbulator of the heat exchanger of the present invention to extend beyond the thermal footprint region, such that the boundary between the segment with non-straight fins and the segment with straight fins is located spaced from the boundary delimiting the thermal footprint region and outside of said thermal footprint region.
Likewise, it is also possible for the segment with straight fins of the at least one turbulator of the heat exchanger of the present invention to extend towards the thermal footprint, with a part of the segment with straight fins being inside the thermal footprint region, such that the boundary between the segment with non-straight fins and the segment with straight fins is located spaced from the boundary delimiting the thermal footprint region and inside said thermal footprint region.
These spacing conditions, according to the preferred examples, can be afforded both in the flow direction and in the transverse directions of the flow and both independently.
Preferably, the thermal footprint is rectangular with two sides parallel to the longitudinal direction and two sides perpendicular to the longitudinal direction.
Preferably, when the conduit has a configuration consisting of two flat walls parallel to and spaced from one another, it is formed by a flat wall for heat exchange with the heat source located in the external part of said wall and, an also flat cover or covering which is placed over the flat heat exchange wall, configuring the inner space of the conduit.
Preferably, the boundary between the segment with non-straight fins and the segment with straight fins of the at least one turbulator of the heat exchanger of the present invention is a straight line transverse to the longitudinal direction, the main flow direction; also preferably, the distances between the thermal footprint region and the boundary between the segment with non-straight fins and the segment with straight fins are measured in the longitudinal direction.
With respect to the at least one turbulator of the heat exchanger of the present invention, in a possible embodiment thereof, at least one segment with straight fins is arranged in a region completely outside the thermal footprint region, such that an adjacent non-straight fin section is arranged in a region containing at least one thermal footprint region and extends beyond the boundary of said thermal footprint region.
According to this embodiment, in those cases where the heat exchange footprint has a significant area of influence, it is possible to increase heat exchange by extending the region of the segments with non-straight fins, thereby favoring a more efficient heat discharge.
Preferably, in the at least one turbulator of the heat exchanger of the present invention, according to the flow direction, between the boundary delimiting a thermal footprint region and the boundary delimiting the attachment of a segment with non-straight fins with an adjacent segment with straight fins of the turbulator or of a segment with straight fins with an adjacent segment with non-straight fins, there is a distance comprised by a transition area, wherein the boundary delimiting the attachment of a segment with non-straight fins with an adjacent segment with straight fins or vice versa:
This transition segment allows the path of the curved channels, established by the fins of the segments with non-straight fins, to be adapted to the straight channels formed by the fins of the segments with straight fins. Preferably, when the non-straight paths are curved and winding paths, the point where the tangent to the curved path coincides with the direction of the straight channels is chosen such that there is continuity in the derivative of the path. In a winding path and following the flow direction, this condition of tangency is verified in the area where there is a maximum or a minimum, with the path being viewed as a function extending along the flow direction.
In this description, “boundary of the thermal footprint region” is interpreted to mean the perimeter line demarcating the thermal footprint region separating points which are located inside the thermal footprint and points located outside the thermal footprint.
As described above, according to a preferred embodiment, the at least one conduit comprises a first wall corresponding to the heat exchange wall, a second wall spaced from the first wall, and side walls connecting the first and second walls. More preferably, the first and second walls of the at least one conduit are parallel to one another. More preferably, the distance between the respective inner faces of the first and second walls of the at least one conduit is less than or equal to 40 mm, preferably less than or equal to 30 mm, and more preferably less than or equal to 20 mm.
This is a very compact configuration which establishes an inner configuration of the conduit which, according to a cross-section, presents a constant thickness. If the inner face of the first wall is furthermore flat, it allows the turbulator to have a flat configuration with thickness allowing the distance between the first wall and the second wall.
Accordingly, the term “thickness” used in this application should in no case be understood to mean the thickness of the wall of the turbulator.
Preferably, the at least one turbulator comprises a plurality of different flow channels (i.e., more than one flow channel) which are distributed along a direction transverse to the flow direction, i.e., occupying the width of the turbulator, and each flow channel being separated from one another, such that there are formed in this turbulator configuration a plurality of divided flow paths distributed transversely and extended along the flow direction of the liquid coolant. According to this particular turbulator configuration in which there is a plurality of flow channels distributed according to the transverse direction and separated from one another, the segments with straight fins and the segments with non-straight fins preferably coincide along the flow direction for all the rows of fins.
Preferably, the at least one turbulator of the heat exchanger of the invention is arranged in a centered position between the side walls in which there is a respective bypass distance between each side wall and the turbulator. Preferably, said bypass distance is comprised between 0 and 20 mm, and more preferably a distance smaller than the width of the channels of the turbulator so as to favor the passage of the main flow through the inside of the channels in which the greatest heat exchange occurs. In the case of non-straight fins of wavy type, the bypass distance measured between the side edge of the fin and each respective side wall of the heat exchanger is variable (as a result of the effect of the wave of the fins). Therefore, in this application, “bypass distance” is understood to mean the minimum distance between the fin and the side wall of the conduit, i.e., the distance between a maximum (corresponding to the peak if it is a sine wave) of a wave of a non-straight segment with fins if viewed as a function in the longitudinal direction and the side wall.
Preferably, the at least one turbulator comprises k different/differentiated segments with straight fins distributed along the flow direction and n different/differentiated segments with non-straight fins distributed along the flow direction. It is understood that the k different segments with straight fins and the n different segments with non-straight fins are intercalated with one another, such that a segment with straight fins is connected to a segment with non-straight fins and so on and so forth.
The applicant has verified that, the value of k is preferably comprised between 1 and 30.
The applicant has also verified that, the value of n can preferably be any of the three following values: (a) equal to k; (b) k+1; or (c) k−1, if k is greater than 1.
The non-straight segments with fins have a greater capacity to exchange heat with the liquid coolant, and therefore they are suitable to be located on the thermal footprint region. In preferred examples, there can be a thermal footprint region or a plurality of thermal footprint regions. When there is a plurality of thermal footprint regions on which the turbulator has segments with non-straight fins, these segments with non-straight fins are connected by means of segments with straight fins such that the liquid coolant passes from a segment with non-straight fins to another contiguous segment also with non-straight fins in a guided manner through the segment with straight fins. It has been demonstrated that the entrainment forces generated by the straight fins, contrary to what was expected, give rise to a lower pressure drop than if a free space is left in between to prevent this entrainment effect, for example, by the presence of limiting layers on the surfaces of the fins. In other words, heat exchange is more efficient overall and a lower pressure drop is obtained.
When the value n (number of segments with non-straight fins) is equal to k (number of different segments with straight fins), the turbulator of the invention has at one of its ends, according to the flow direction, a segment with straight fins which favors the guiding of the flow also between the inlet and the turbulator, or between the turbulator and the outlet of the liquid coolant, where this end with the segment with straight fins is located.
When the value n is equal to k−1, when k is greater than 1 (case “c”), then the distribution of segments of the turbulator of the invention according to the flow direction is such that two segments with straight fins are always located between a respective segment with non-straight fins, such that at both ends of the turbulator, according to the flow direction, there is a segment with straight fins, thereby favoring guiding when feeding the liquid coolant both from the inlet and to the outlet of the exchanger.
Lastly, when the value n is equal to k+1, the turbulator of the invention has a distribution of segments according to the flow direction in which a segment with straight fins is located between two segments with non-straight fins, such that, in this case, at the ends of the turbulator there are always segments with non-straight fins located on the thermal footprint regions and positioned at the end along the flow direction. There are no parts of the turbulator between these two ends and the liquid coolant inlet or outlet.
In a particular embodiment of the at least one turbulator of the invention, the turbulator comprises at least one segment with non-straight fins with a length Lwn along the flow direction comprised between 2 and 500 mm, preferably from 2 to 250 mm, and more preferably from 2 to 100 mm.
In a particular embodiment of the at least one turbulator of the invention, the turbulator comprises at least one segment with straight fins with a length Lsk along the flow direction comprised between 2 and 500 mm, preferably from 2 to 250 mm, and more preferably from 2 to 100 mm.
In a particular embodiment of the at least one turbulator of the invention, the turbulator has a length Lwn along the flow direction of each of the n segments with non-straight fins which is the same.
In an alternative embodiment of the at least one turbulator of the invention, the turbulator has a length Lwn along the flow direction of at least one of the n segments with non-straight fins which is different from at least another one of the n segments with non-straight fins.
In a particular embodiment of the at least one turbulator, the turbulator has a length Lsk along the flow direction of each of the k segments with straight fins which is the same.
In an alternative embodiment of the at least one turbulator, the turbulator has a length Lsk along the flow direction of at least one of the k segments with straight fins which is different from at least another one of the k segments with straight fins.
In a particular embodiment of the at least one turbulator, the turbulator has a total length Ltotal measured along the flow direction which is comprised between 1 and 1500 mm.
In a particular embodiment of the at least one turbulator, the turbulator has a width, calculated as the distance between the two farthest points in the transverse direction Y-Y′, which is comprised between 500 mm and 15 mm, more preferably between 300 mm and 15 mm, and more preferably between 100 mm and 15 mm.
In a particular embodiment of the at least one turbulator, and in the case where at least one segment with non-straight fins is of a wavy type, the attachment or connection between a straight fin section and an adjacent non-straight fin section occurs at a point of the wave of the segment with non-straight fins corresponding to a maximum or a minimum.
The applicant has found that this attachment between a straight fin section and a non-straight fin section, adjacent to one another, at a point corresponding to a maximum or a minimum of the wave advantageously optimizes the continuous channel created for the passage of fluid in the attachment of both different segments with fins.
Likewise, according to an embodiment in which there are several segments with straight fins, at least two segments with straight fins have a different attachment, that is, one at a point corresponding to a maximum and another at a point corresponding to a minimum. According to this configuration, corresponding with a maximum means that the fins of the segment with straight fins are arranged closer to one of the sides of the conduit, reducing the side channel bypass, but leaving a larger passage channel on the other side.
The greater ease of passage of the liquid coolant on the side that leaves a larger passage channel is limited in a different position along the flow direction by the segment with straight fins which is attached at a point corresponding to a minimum since the fins of this segment is arranged closer to the side opposite the first side. The bypass flow is limited by “the bottleneck” or restriction imposed by the narrower passage, and therefore although it is in a position along the different flow direction, the restriction is the same on both sides, finally favoring the passage of the liquid coolant through the channels of the turbulator which exchange heat with the liquid coolant more efficiently. The distribution of the liquid coolant on the side by the bypass channels is similar insofar as the turbulator has an even number of straight segments, such that half are attached by a maximum and half by a minimum. In contrast, if the turbulator has an odd number of straight segments (for example, three: two connected by a maximum and one by a minimum) of the same length, distribution of the liquid coolant on the side by the bypass channels is not the same given that the channel having a smaller number of straight segments arranged closer to the side wall offers less flow resistance.
In a particular embodiment of the at least one turbulator, the at least one channel of the turbulator comprises, along the flow direction, at least one segment with straight fins, wherein each segment with straight fins is alternated with two segments with non-straight fins, such that each segment with straight fins is arranged in an intermediate position between two adjacent segments with non-straight fins along the flow direction.
According to a possible example of the heat exchanger, the arrangement of non-straight segments and straight segments of the at least one turbulator of the heat exchanger of the present invention is such that it is invariable with respect to a 180° rotation according to an axis perpendicular to the heat exchange wall. This advantageous configuration with the same geometry (i.e., with the same position of the turbulator) allows preventing errors when the operator assembles the turbulator in the heat exchanger. If the preceding condition is not met, there is the risk of the turbulator being assembled in two different orientations in the exchanger, giving rise to two different parts.
Preferably, it is of interest that the number of segments with non-straight fins in the turbulator is greater than the number of segments with straight fins.
Preferably, the number of segments with straight fins in the turbulator is an even number, because in the case of an odd number, the condition of the geometry being invariable upon rotating it 180° C. with respect to the axis perpendicular to the heat exchange wall cannot be met because, unlike a segment with non-straight fins, the segment with straight fins is arranged closer to one side or to the opposite side, but one and the same segment with straight fins cannot be arranged closer to all two sides, which is what would be required in the center.
According to a specific possible example of the heat exchanger, the at least one turbulator comprises three segments with non-straight fins and two segments with straight fins, connected to one another continuously, with a segment of each type being intercalated along the flow direction, giving rise to the following configuration of five continuous segments in this order: a first segment with non-straight fins at one end, a first segment with straight fins, a second segment with non-straight fins, a second segment with straight fins, and a third segment with non-straight fins at the opposite end.
According to a possible example of the heat exchanger, the heat exchanger comprises a turbulator comprising a plurality of segments with straight fins, and preferably three segments with non-straight fins, and wherein each segment with non-straight fins is formed by wavy fins with a wave formed by: (a) straight segments, preferably a square wave, or (b) with a curved wave, preferably a sine wave, and wherein:
Preferably, the turbulator of the heat exchanger is formed by a single metal sheet, which extends in the longitudinal direction X-X′ following a configuration determined by the flow direction, and which can also extend according to a direction Y-Y′ transverse to direction X-X′.
Preferably, said single metal sheet can be formed by a stamping process, although other manufacturing means are possible.
Preferably, possible attachment means for attaching the structure of the turbulator to the inner surface of the conduit of the heat exchanger is welding, brazing, adhesion, or other similar attachment methods.
In a second inventive aspect, the present invention provides a heat exchanger module comprising at least:
These and other features and advantages of the invention will be shown more clearly based on the following detailed description of a preferred embodiment, provided solely by way of illustrative and non-limiting example in reference to the attached figures.
According to the first inventive aspect, the present invention relates to a heat exchanger device (1), preferably suitable for cooling one or more external electric or electronic elements or components with respect to the exchanger, such as one or more semiconductor devices (D) intended for switching, amplifiers, etc.
These electric or electronic elements or components have extremely demanding cooling requirements since the thermal energy to be discharged is very high and must be discharged through a very small contact surface.
According to a first aspect of the invention, the embodiment of the heat exchanger (1) is shown in its assembled configuration seen in a perspective view in
According to the orientation shown in
As seen in
When viewed from the top, the cover (1.3) has an external shape that is substantially the same as the shape of the heat exchange wall (1.1) because it covers most of the area of the heat exchange wall (1.1).
In
According to this embodiment, this turbulator (1.2) is formed by a single metal sheet formed by stamping. This sheet extends in the longitudinal direction X-X′ following a configuration determined by the flow direction (DF) and also according to a direction Y-Y′ transverse to the longitudinal direction X-X′. This thick arrow is slightly wavy in a central area denoting that the flow follows a wavy path in a central segment under which the arrow is located. In this specific case, taking into consideration the longitudinal path X-X′, the turbulator (1.2) has three segments with wavy fins (1.2.1), wherein two adjacent segments with wavy fins (1.2.1) are connected by an intermediate segment with straight fins (1.2.2).
Now, taking into consideration a cross-section of the turbulator (1.2), all the sections have a wavy configuration. In this embodiment, the turbulator (1.2) is obtained from a metal sheet which is configured in the described shape by deformation.
The straight segments of the lower ridges (1.2.4) rest on the inner surface of the heat exchange wall (1.1) and the upper ridges (1.2.3) are supported on the inner surface of the cover (1.3). According to this embodiment, the attachment between the turbulator (1.2) and the cover (1.3) and the attachment between the turbulator (1.2) and the heat exchange wall (1.1) are carried out by brazing in the contact regions, mainly through the areas of the turbulator (1.2) which correspond with the straight segments that have been described.
Therefore, as shown in
The turbulator (1.2) is therefore housed in the space generated by the heat exchange wall (1.1) and the cover (1.3), causing the presence of passage channels. The fluid is forced to flow following the inner channels (Chi) defined by the turbulator (1.2) plus the two side channels (Chl).
In this same
Returning to
The fluid flow has an inlet/outlet (1.1.2) in the form of a perforation in the heat exchange wall (1.1) located in an area close to the end, and an outlet/inlet (1.1.3) also in the form of a perforation in the heat exchange wall (1.1) located in an area close to the end opposite the inlet/outlet (1.1.2).
The notation inlet/outlet or outlet/inlet indicates that the perforations allow flow in both directions such that, when one perforation acts as an inlet, the other acts as an outlet, so the option before the slash “/” would be considered, and for flow in the opposite direction, the option located on the right side of the slash “/” would be considered.
The two perforations are in an area close to the end of the heat exchanger (1) but they coincide with the inner space demarcated by the cover (1.3). For that reason, in this embodiment, the ends of the cover (1.3) have a rounded termination, according to the top view configuration.
According to the longitudinal direction X-X′, it is also observed that the turbulator (1.2) shows segments where the wave extends longitudinally in a sinusoidal configuration, i.e., a wavy configuration, also in the longitudinal direction, and a segment where the fins extend longitudinally according to a straight configuration. These two different segments of the turbulator (1.2) are identified as segment with non-straight fins (1.2.1) and segment with straight fins (1.2.2), respectively.
According to the configuration show in
This bottom plan view shows the plate giving rise to the heat exchange wall (1.1) extending along the perimeter by means of fixing prolongations (1.1.1). The same figure, not including references, shows other means which allow the fixing of the plate, and by extension, of the heat exchanger as a whole. Fixing means are perforations for the passage of threaded stud bolts or passages in the form of open grooves which also allow the passage of threaded stud bolts but with greater positional play.
This bottom view shows inlet/outlet port (1.1.2) for the liquid coolant and the outlet/inlet port (1.1.3) also for the liquid coolant.
The area (S) for receiving one or more external electric or electronic devices (D) allows the surface of the heat exchange wall (1.1) and the outer surface of the electric or electronic device (D) to be cooled to be attached using intermediate substances.
According to one embodiment, this intermediate substance is an adhesive which secures the close attachment between the surfaces to be attached. According to another embodiment, the intermediate substance is a paste with high coefficient of thermal conduction in order to favor heat transfer from the electric or electronic device (D) to the heat exchange wall (1.1).
As indicated, the area (S) for receiving one or more external electric or electronic devices (D) does not have to coincide with the configuration of the surface to be cooled. In this embodiment, the size of each rectangular region consisting of the area (S) for receiving one or more external electric or electronic devices (D) is larger than the surface to be cooled. Among other advantages, it prevents positional errors from hindering the coincidence of the surface (S) for receiving one or more external electric or electronic devices (D) with the surface to be cooled.
Additionally, using areas (S) for receiving one or more external electric or electronic devices (D) of a larger size than the areas to be cooled allows the same heat exchanger (1) to be valid for different configurations of devices (D) to be cooled, allowing a plurality of configurations to coincide at all times with the areas (S) for receiving one or more external electric or electronic devices (D).
In this case, “corresponding” areas is used to establish a comparison of the area on a surface and the area on the opposite surface of the heat exchange wall (1.1) projecting according to a direction perpendicular to said wall (1.1).
Each electric or electronic device (D) to be cooled is in thermal communication through a contact region which, in this embodiment, is established in the area (S) for receiving one or more external electric or electronic devices (D). In the region where thermal contact is established, heat transfer occurs, preferably from the electric or electronic device (D) to the conductive body formed by the heat exchange wall (1.1). The greater the thickness of the heat exchange wall (1.1), the greater heat diffusion will be in the direction of the main plane of the heat exchange wall (1.1).
Preferably, the heat exchange wall (1.1) is formed from a metal sheet to facilitate heat transfer from the area (S) for receiving one or more external electric or electronic devices (D) to the opposite surface by conduction. The opposite surface is the surface on which the turbulator (1.2) is arranged.
There is an area on the opposite surface in which heat transfer increases the temperature. Although the diffusion effect means that the area of influence is greater than the area in which heat transfer occurs by contact with the electric or electronic device (D), the perimetral region of the region of influence shows a temperature gradient blurring the limit of the region of influence.
However, while this is the case, when the thermal footprint (H) is identified, the footprint given by the projection according to the direction perpendicular to the heat exchange wall (1.1) of the area corresponding to the heat source, for example a semiconductor, in contact with the opposite or outer surface, is taken as reference. In other words, if the contact region with the electric or electronic device (D) in which heat transfer to the heat exchange wall (1.1) occurs is a rectangle, the thermal footprint (H) on the opposite surface will be the same rectangle, with the same dimensions, represented on the opposite surface according to the projection given by the direction perpendicular to the wall (1.1).
According to the teachings of the state of the art, the regions that do not have to be cooled preferably cause the lowest pressure drop possible and this is achieved by leaving the passage of the liquid coolant free of surfaces causing the deflection thereof or the emergence of limiting layers which generate an entrainment effect, and therefore cause a pressure drop.
Contrary to this preconception, it has been found that the inclusion of segments with straight fins (1.2.2) located between segments with non-straight fin (1.2.1), instead of causing a greater pressure drop, has been observed to give rise to a lower pressure drop. In particular, segments with straight fins (1.2.2) were used such that the channels formed by the fins of the segments with non-straight fins (1.2.1) show continuity with the channels formed by the segments with straight fins (1.2.2).
Likewise, in this embodiment, the configuration of the wavy fluid path according to the longitudinal direction of the non-straight fins (1.2.1) is such that transition with the segment with straight fins (1.2.2) is established where the tangent of the wavy path of the walls of the channel is parallel to the longitudinal direction X-X′.
It has been proven that the existence of a segment with straight fins (1.2.1), in addition to favoring a lower pressure drop, gives rise to greater structural rigidity of the heat exchanger (1), particularly the flexural rigidity of the main plane of the heat exchange wall (1.1).
According to the first embodiment shown in
The boundary between each segment with non-straight fins (1.2.1) and segment with straight fins (1.2.2) of the turbulator (1.2) has been indicated in
Therefore, both boundary straight lines are shown parallel to and spaced from one another, giving rise to a transition region (Tr) between said two straight lines. In the specific case of the first embodiment shown in
In this first embodiment shown in the
The length Lwn in the longitudinal direction X-X′ of each segment with non-straight fins (1.2.1) is greater than the length in the longitudinal direction X-X′ of the respective thermal footprint (LH1, LH2, LH3), and there is a respective transition area (Tr) between the respective ends of each thermal footprint (H) with the transverse line of transition between a segment with straight fins and a segment with non-straight fins, wherein said respective transition area (Tr) is located inside the respective segment with non-straight fins (1.2.1). In this first embodiment of the invention, it is also observed that the length Lwn in the longitudinal direction X-X′ of each of the three segments with non-straight fins (1.2.1) is slightly greater compared to the length Lsk of each of the two segments with straight fins (1.2.2). In this case, the length of all the segments with non-straight fins (1.2.1) is the same and the length of all the segments with straight fins (1.2.2) is also the same.
Preferably, when the fins of the segment with non-straight fins (1.2.1) have a wavy or periodic configuration, the distance of the transition region Tr1, Tr2, Tr3 is such that the path of the waves reaches a maximum or a minimum, meaning that the tangent to the path (viewed in a plane parallel to the plane of the heat exchange wall (1.1)) is parallel to the longitudinal direction X-X′.
In this same
When the entire segment with non-straight fins (1.2.1) is arranged closer to one side, it approaches the side wall of the conduit and the width of the bypass channel (BP) is reduced. Since one segment is arranged closer to one side and the other segment closer to the other side, passage to the two bypass channels (BP) located on the end sides is simultaneously restricted overall.
According to a second embodiment of the invention shown in
In this embodiment, as shown in
The electric or electronic devices (D) to be cooled are shown in
Lastly,
| Number | Date | Country | Kind |
|---|---|---|---|
| 22382929.2 | Oct 2022 | EP | regional |
