The present invention refers generally to a plate heat exchanger wherein at least two injectors are arranged in a wall portion of a first inlet channel, each injector being arranged to supply a first fluid to more than one of the first plate interspaces.
The present invention refers generally to a plate heat exchanger, in particular a plate heat exchanger in the form of an evaporator, i.e. a plate heat exchanger designed for evaporation of a cooling agent for various applications, such as air conditioning, cooling systems, heat pump systems, etc.
A plate heat exchanger, typically includes a plate package with a plurality, of first and second heat exchanger plates which are joined to each other and arranged side by side in such a way that 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 separated from each other and provided side by side of each other in an alternating order in the plate package. Substantially each heat exchanger plate has at least a first porthole and a second porthole, wherein the first portholes form a first inlet channel to the first plate interspaces and the second portholes form a first outlet channel from the first plate interspaces.
The cooling agent supplied to the inlet channel of such a plate heat exchanger for evaporation is usually present both in a gaseous state and a liquid state, i.e. it is a two-phase evaporator. It is then difficult to provide an optimum distribution of the cooling agent to the different plate interspaces in such a way that an equal quantity of cooling agent is supplied and flows through each plate interspace.
DE10024888 discloses one example of a well known solution to the distribution problem wherein the inlet port of each heat exchanger plate in the plate package comprises a distributor distributing the refrigerant from the inlet channel into the plate interspaces.
DE 10 2006 002 018 discloses one example of another well known principle to the distribution problem. The refrigerant supplied to the plate heat exchanger is distributed into the inlet channel from one end thereof and further into the plate interspaces via a nozzle arrangement. Two principles are shown regarding the nozzle arrangement. In the first principle the nozzle arrangement is in the form of a plurality of small holes arranged in the circumferential, longitudinal wall portion of the inlet channel. The small holes act as spray nozzles distributing the refrigerant into the plate interspaces. In the second principle a flute is arranged to extend inside and along the inlet channel. The flute is provided with plurality of holes acting as nozzles distributing the refrigerant along the inlet channel and further into the plate interspaces.
In this general prior art plate heat exchanger the cooling agent is introduced at one end of the longitudinal first inlet channel, i.e. the first port hole, for further distribution in the form of droplets along the first inlet channel and further into each of the individual first plate interspaces. First of all it is very hard to control the flow inside the first inlet channel. There is always a risk of that the energy content of the inserted fluid is too high, whereby a part of the flow supplied to the inlet channel via its inlet port will meet the rear end of the inlet channel and be reflected thereby in the opposite direction Thereby the flow in the inlet channel is very chaotic and hard to predict and control. Further, the pressure drop of the cooling agent increases with the distance from the inlet of the first inlet channel, whereby the distribution of cooling agent between the individual plate interspaces will be affected. Thereby it is hard to optimize the efficiency of the plate heat exchanger. It is also known that the angular flow change that the droplets of the cooling agent must undergo when entering the individual plate interspaces from the first inlet channel contributes to a pressure drop.
Generally the efficiency of a plate heat exchanger at part load is a raising issue for the purpose of reducing the energy consumption. By way of example, laboratory scale trials have shown that a cooling system relating to air-conditioning may save 4-10% of its energy consumption just by improved evaporator function at part load for a given brazed plate heat exchanger. Further, an evaporator system is typically only operating at full capacity for 3% of the time, while most evaporators are designed and tuned for a full capacity operation duty. More focus is put on how the evaporator performs at different operation duties instead of being measured at only one typical operation duty. Also, the market applies so called seasonal efficiency standards. The standards may vary between different states and regions. Typically, such standards are based on a consideration including different working loads, whereby most evaporators are designed and tuned in view of a specific standard. However, during normal operation the work load varies greatly and it hardly reflects the fictive conditions used for the standard.
The object of the present invention is to provide an improved plate heat exchanger remedying the problems mentioned above.
Especially it is aimed at a plate heat exchanger which allows a better control and distribution of the supply of cooling agent along the first inlet channel and/or between the individual plate interspaces to thereby allow the efficiency of the plate heat exchanger to be improved.
A further object of the invention is to provide a plate heat exchanger which allows the supply of cooling agent to be varied and optimized depending on the actual operation duties.
This object is achieved by a plate heat exchanger including a plate package, which includes a number of first heat exchanger plates and a number of second heat exchanger plates, which are joined to each other and arranged side by side in such a way that 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, wherein the first plate interspaces and the second plate interspaces are separated from each other and provided side by side in an alternating order in the at least one plate package, and wherein substantially each heat exchanger plate has at least a first porthole, wherein the first portholes form a first inlet channel to the first plate interspaces. The plate heat exchanger is characterized in that at least two injectors are arranged in a longitudinal wall portion of the first inlet channel, each injector being received in a through hole extending from the exterior of the plate package to the interior of the first inlet channel and each injector being arranged to supply a first fluid to more than one of the first plate interspaces.
In its general form, the present invention defines the use of at least two injectors arranged in a wall portion of the first inlet channel and each injector is arranged to supply a first fluid to more than one of the first plate interspaces. Thus, instead of supplying the first fluid, e.g. a cooling agent, to the first inlet channel via its single inlet port at one end of its longitudinal extension, a plurality of inlet points are provided in a wall portion defining the first inlet channel and along the longitudinal extension of the first inlet channel. The number of injectors is optional and their positions may be arbitrary for the purpose of providing a sufficient and even distribution along the longitudinal extension of the first inlet channel.
It is to be understood that the position of the at least two injectors in the wall portion is depending on the available space and design of the exterior wall portions of the plate package. This since the at least two injectors most conveniently may be provided in the wall portion by each injector being received in a through hole extending from the exterior of the plate package to the interior of the first inlet channel. This allows for a large degree of freedom when determining the position of the first inlet channel in a plate package. In most prior art plate heat exchangers, the inlet/outlet channels are arranged in the proximity of a corner. By the invention, this must not longer be the case.
By using more than one injector in the inlet channel, the prior art problems with chaotic, uncontrolled flow inside the inlet channel may be reduced or even eliminated. Further, by using more than one injector in the inlet channel, prior art problems relating to pressure drop when using only one single supply via the first inlet channel may be at least reduced or even eliminated, since the travelling distance for the supplied first fluid will be reduced. In fact, by the at least two injectors, the supply of the first fluid may be positioned close to or adjacent each or a plurality of plate interspaces. In case of the injectors being arranged adjacent each plate interspace, the negative impact to the pressure drop caused by the change of flow direction when entering the plate interspace may be reduced or even eliminated. The invention also provides for each plate interspace being supplied with the first fluid from more than one injector, and the injectors may have mutually different directions. This allows for a high utilization of the heat transferring area of each heat exchanger plate. This may in particular be useful for heat exchanger plates having large surface areas and thereby large heat transferring areas.
Thus, the present invention in its most general form provides a wide range of possibilities of how the first fluid, such as a cooling agent, is supplied, and especially where the first fluid is supplied into the plate heat exchanger. This provides for a better possibility in terms of control and optimization of the overall efficiency of the plate heat exchanger no matter its load.
The injectors may be arranged mutually in a number of ways. By way of example, the at least two injectors may be arranged side by side in a row in parallel with the longitudinal extension of the first inlet channel. The at least two injectors may alternatively be arranged side by side in at least two rows in parallel with the longitudinal extension of the first inlet channel. Further, the at least two rows of injectors may be arranged on each side of a longitudinal center line of the first inlet channel. Additionally, the injectors in a first row may be mutually displaced in view of the injectors in a second row.
The at least two injectors may be provided with a nozzle providing a spray pattern, such as a fan shaped or cone shaped, whereby the spray patterns of two adjacent nozzles in one row of injectors or in two adjacent rows of injectors may be set to have an overlap of 10-70%, more preferred 20-60% and most preferred 30-50%.
The term fan shaped and cone shaped spray pattern is used to describe an ejected flow from a nozzle. It is to be understood that a fan shaped spray pattern results in an essentially narrow rectangular projected area whereas a cone shaped spray pattern results in an essentially circular projected area. By the overlap, a substantially even distribution of the first fluid may be provided across the plurality of first plate interspaces, whereby each first plate interspace may be provided with essentially the same amount of first fluid and with essentially the same inherent energy content and essentially the same inherent density.
The overlap is generally to be calculated as seen on a portion of the envelope surface of the first inlet channel subjected to the spray pattern. In terms of a generally fan shaped spray pattern, the overlapping area provided by two adjacent spray nozzles has an essentially rectangular area. Likewise, in terms of a generally cone shaped spray pattern, the overlapping area provided by two adjacent spray nozzles corresponds to that of two partially overlapping circles. The overlap compensates at least partly for blur along the periphery of the spray pattern due to the spreading of the individual droplets comprised in the thus distributed fluid.
The at least two injectors may be arranged in the first inlet channel to direct a flow of fluid to the first plate interspaces via a part of the inner envelope surface of the first inlet channel, said part corresponding to, as seen in a cross section of the longitudinal envelope surface transverse the longitudinal extension of the first inlet channel, less than 75% of the cross section of the longitudinal envelope surface, more preferred less than 65% of the cross section of the longitudinal envelope surface and most preferred less than 50% of the cross section of the longitudinal envelope surface.
Accordingly, the first fluid may be supplied to only a portion of the envelope surface as seen in a cross section transverse the longitudinal extension of the first inlet channel. The portion to be selected depends on a number of factors such as the provision of and the position of any distributors adjacent the first inlet channel, the pressure of the supplied first fluid and any surface pattern on the individual heat exchanger plates. In one possible embodiment the fluid flow may be directed to a lower portion of the first fluid channel, whereby the first fluid when entering the first plate interspaces may be distributed across essentially the full heat transferring surface of the heat exchanger plates. Still, it is to be understood that this is only one, non-limiting example. It is also to be understood that one row of injectors may be directed to cover one portion of the cross section of the envelope surface, whereas another row of injectors may be directed to cover another portion of the cross section of the envelope surface. Further the surface area of the portion as such is determined by the spray pattern provided by each injector and any nozzle mounted thereto.
Each injector may be provided with an individual valve, or a group of injectors may be provided with a common valve. By the valve, the fluid supply to individual injectors or group of injectors may be controlled in order to allow better control of the efficiency of the heat exchanger. It is to be understood that in its easiest form the injectors may be constituted by valves distributing the first fluid.
The group of injectors may comprise injectors from at least two rows of injectors.
The first heat exchanger plates and the second heat exchanger plates may be permanently joined to each other. The heat exchanger plates in the plate package may be connected to each other through brazing, welding, adhesive or bonding.
The through hole may be formed by plastic reshaping, by cutting or by drilling. The term plastic reshaping refers to a non-cutting plastic reshaping such as thermal drilling. The cutting or drilling may be made by a cutting tool. It may also be made by laser or plasma cutting.
The at least two injectors may be arranged to direct a supply of the first fluid essentially in parallel with the general plane of the first and the second heat exchanger plates.
The supply of the first fluid to the injectors may be controlled by a controller. This allows for the overall efficiency of the plate heat exchanger to be controlled with a very high efficiency no matter actual operation load. The injectors may be controlled individually or in groups.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which
For better understanding of the invention, an example of a typical plate heat exchanger 1 will be disclosed with reference to
As is clear from
Every second plate interspace thus forms a respective first plate interspace 3 and the remaining plate interspaces form a respective second plate interspace 4, i.e. the first and second plate interspaces 3 and 4 are provided in an alternating order in the plate package P. Furthermore, the first and second plate interspaces 3 and 4 are substantially completely separated from each other.
The plate heat exchanger 1 may advantageously be adapted to operate as an evaporator in a cooling circuit (not disclosed). In such application, the first plate interspaces 3 may form first passages for a cooling agent whereas the second plate interspaces 4 may form second passages for a fluid, which is adapted to be cooled by the cooling agent.
The plate package P also includes an upper end plate 6 and a lower end plate 7, which are provided on a respective side of the plate package P and form the end plates of the plate package P.
In the embodiment disclosed, the heat exchanger plates A, B and the end plates 6, 7 are permanently connected to each other. Such a permanent connection may advantageously be performed through brazing, welding, adhesive or bonding.
As appears from especially
Now referring to
Each of the at least two injectors 25 is arranged in a through hole 20 having an extension from the exterior of the plate package P to the first inlet channel 9, the through hole 20 may be formed by plastic reshaping, by cutting or by drilling. The term plastic reshaping refers to a non-cutting plastic reshaping such as thermal drilling. Thermal drilling is also known as flow drilling, friction drilling or form drilling. The cutting or drilling may be made by a cutting tool. It may also be made by laser or plasma cutting. The through hole 20 as such may be provided with a bushing, sealing or the like (not shown) to ensure a fluid tight connection.
The number of first plate interspaces 3 served by one and the same injector 25 may vary. The dimensioning parameter is essentially the requirement of an even distribution across the plate interspaces 3 to be served by the specific injector 25. It is to be understood that influencing parameters are by way of example spray pattern, the distance between a nozzle 26 of the injector 25 and the entrance to the plate interspace 3 and fluid pressure.
Now turning to
In the following a number of different patterns of the injectors will be exemplified.
The injectors 25 may be provided with nozzles 26 providing a fan shaped spray pattern 30, see
As illustrated in
Referring to
It is to be understood that the at least two injectors may be arranged to direct the supply of the first fluid in any arbitrary direction within the first inlet channel 9. This is especially the case if the injectors 25 are provided with atomizing nozzles. However, it is preferred that the flow is directed essentially in a direction in parallel with a general plane 16 of the first and the second heat exchanger plates A, B, see
The invention has been illustrated and disclosed throughout this document with the port holes 8 and thereby also the first inlet channel 9 arranged in the corners of rectangular heat exchanger plates. It is however to be understood that also other geometries and positions are possible within the scope of protection.
The port holes 8 have generally been illustrated and disclosed as circular holes. It is to be understood that also other geometries are possible within the scope of the protection.
The invention has generally been described based on a plate heat exchanger having first and second plate interspaces and four port holes allowing a flow of two fluids. It is to be understood that the invention is applicable also for plate heat exchangers having different configurations in terms of the number of plate interspaces, the number of port holes and the number of fluids to be handled.
The four portholes 8 are in the disclosed embodiment provided in the proximity of a respective corner of the substantially rectangular heat exchanger plates A, B. It is to be understood that other positions are possible, and the invention should not be limited to the illustrated and disclosed positions.
Yet another embodiment is disclosed in
A plurality of injectors 25 are received in through holes 20 arranged in a wall portion of the casing 40. Each injector 25 is communicating with a valve 29 and the valves 29 are in communication with a controller. Each injector 25 may be provided with a nozzle. It is also to be understood that the injectors as such may be constituted by valves.
The first and second heat exchanger plates may be provided with distributors (not disclosed) for the purpose of providing a throttling of the first fluid in the transition area between the first inlet channel and the individual first plate interfaces. Thereby a pressure drop of the cooling agent is obtained when it enters the respective first plate interspace. This may further enhance the distribution of the first fluid across the area of the first plate interspace. The distributors may be arranged in a number of ways and a few examples will be given below.
The first and second heat exchanger plates may have distributors integrated in the heat exchanger plates. The distributors may by way of example, be formed as a pressed profile in the heat exchanger plates around or adjacent the first port hole, whereby the pressed profile as such acts as a distributor. The distributors may also by way of example be a pressed profile provided with through holes acting as distributors. It is also possible to have distributors arranged between the pairs of adjacent first and second heat exchanger plates in the area in or around the first port holes. Such distributor may be in the form of a profile loosely received between a pair of first and second heat exchanger plates, or a profile joined to one of the two heat exchanger plates forming a pair. Such distributor may be provided with trough holes or be provided with recesses which together with the heat exchanger plates act as distributors.
It is to be understood that the invention is applicable also to plate heat exchangers of the type (not disclosed) where the plate package is kept together by tie-bolts extending through the heat exchanger plates and the upper and lower end plates. In the latter case gaskets may be used between the heat exchanger plates. The invention is also applicable to plate heat exchangers (not disclosed) comprising pairwise permanently joined heat exchanger plates, wherein each pair forms a cassette. In such solution gaskets are arranged between each cassette.
The invention is not limited to the embodiment disclosed but may be varied and modified within the scope of the following claims, which partly has been described above.
Number | Date | Country | Kind |
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12171917 | Jun 2012 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/061983 | 6/11/2013 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2013/186194 | 12/19/2013 | WO | A |
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Number | Date | Country | |
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20150122468 A1 | May 2015 | US |