Plate heat exchanger having permanently joined plates.
The present invention refers to a plate heat exchanger comprising a package of heat exchange plates, each having a peripheral portion and inside of this a heat exchange portion and several port portions with throughflow ports, the heat exchange plates being permanently joined to adjacent heat exchange plates in a package both along their peripheral portions and at many places in their heat exchange portions in such manner that they leave flow passages between adjacent heat exchange plates, the ports of the plates being placed in line with each other forming first inlet and outlet channels through the package for a first heat exchange medium, which communicate with every second flow passage between the heat exchange plates, and second inlet and outlet channels through the package for a second heat exchange medium, which communicate with remaining flow passages between the heat exchange plates, and along each of the inlet and outlet channels the port portions of adjacent heat exchange plates, which form a flow passage separated from the inlet and outlet channel, respectively, being permanently joined around the inlet and outlet channel between an outer line and an inner line located closer to the inlet and outlet channel respectively.
Plate heat exchangers of this kind are previously known, for example by US 3 240 268 and GB A 2 005 398. By that the heat exchange plates are permanently joined to each other no separate gaskets are required between the plates and neither any outer frame to hold the plates together. Therefore, it is possible to produce plate heat exchangers of this kind relatively cheap. The expression permanently joined refers mainly to soldering but also for example welding or glueing.
An essential disadvantage with known permanently joined plate heat exchangers is that they are limited to certain pressures, which are considerably lower than those permitted in a plate
heat exchanger provided with an outer frame to keep the heat exchange plates together. At a pressure which overloads a permanently joined plate heat exchanger a leakage will arise, and it has now shown that such leakage as a rule is located to the port portions and/or the peripheral portions of the heat exchange plates in connection with the inlet and outlet channels. The reason for this is probably that the plate heat exchanger in the port portions of the plates has relatively large projected areas without connecting joints between the heat exchange plates. The joints located closest to this portions therefore risk overloading and tearing up. In known plate heat exchangers these joints are located at a considerable distance from the edge of the inlet or the outlet channels and usually first at the peripheral portions of the plates, which as mentioned are joined to a peripheral sealing between the heat exchange plates. Said considerable distance of the known plate heat exchangers has been considered necessary to give sufficient space for a sealing ring, which must be placed in the area between the said outer and the said inner line at an end plate of the plate heat exchanger. Furthermore a margine is required at the area for said sealing ring depending on that during pressing of the heat exchange portions of the heat exchange plates the usually round ports often are deformed so that they become slightly oval.
The object of the present invention is to eliminate the above mentioned disadvantages of the previously known permanently joined plate heat exchangers and to provide a plate heat exchanger of the initially described kind which allows a considerably higher pressure load than previously known plate heat exchangers of this kind.
This object is achieved by a plate heat exchanger of the initially described kind, which mainly is characterized in several means arranged to keep the port portions of the heat
exchange plates together, said means being placed along each of the inlet and outlet channels in the spaces between the plates communicating with said inlet and outlet channels, respectively, and in each such space between the plates being permanently connected to both of the heat exchange plates, delimiting the space between the plates in question, in an area partly around the inlet and outlet channels, respectively, located between said outer line and an adjacent part of the periphery portion.
In a preferred embodiment of the invention each connecting means at least partly constitutes an integral part of a heat exchange plate. Preferably the heat exchange plates are made of a thin material and by means of pressing provided with projections on both of their sides, each connecting means comprising a projection being pressed out from the port portion of a heat exchange plate. The port portions of two adjacent plates, which port portions surround an inlet or outlet channel, communicating with the flow passage formed by the plates, are preferably placed in the two end planes of the plates, located furthest from each other, and each of the connecting means is formed of projections from the adjacent plates, which projections are permanently joined to each other.
Preferably the connecting means placed in the different spaces between the plates, is arranged in line with each other perpendicularly to the heat exchange plates along the inlet and outlet channels, respectively.
Each inlet and outlet channel is open at its one end and closed at its other end, and an end plate placed at the said other end, has a non-penetrated port portion comprising connecting means, which corresponds to said connecting means of the heat exchange plates, in areas around inlet and outlet channels, and stiffening projections pressed out inside of said connecting means.
By providing each heat exchange plate according to the invention with connecting means also within the above said inner line in each port portion, which means is formed by pressing together with the pressing of the remaining portions of the plate, it can be avoided that the ports of the plate become oval. In this way the above mentioned margine of the area for a sealing ring at the end plate of the heat exchanger can be utilized for the forming of the just mentioned connecting means within said inner line in each port portion. Thus, it has shown possible by the invention to improve the resistance of the heat exchanger without requiring the heat exchange areas of the plates or the ports of the plates to be made smaller.
In the following the invention will be described more in detail with reference to the accompanying drawings, in which
figure 1 shows a perspective view of a plate heat exchanger of the kind referring to the invention,
figure 2 shows a part of a heat exchange plate intended for a plate heat exchanger according to the invention,
figure 3 shows a part of an end plate intended for a plate heat exchanger according to the invention, and
figure 4 shows a cross-section view through a plate heat exchanger along the line IV-IV in figure 1.
In figure 1 there Is shown a plate heat exchanger 1, comprising a package of heat exchange plates 2, an end plate 3 and outer cover plates 4a and 4b on the upper side and the lower side respectively of the package. The plate heat exchanger 1 also has a first and second inlet 5 and 6 respectively and a first and second outlet 7 and 8 respectively for two heat exchange media.
In figure 2 there is shown an end portion of an elongated heat exchange plate 2, provided with a press pattern on both of its sides, which extends between two end planes of the heat exchange plate 2. One from the heat exchange plate 2 obliquely projecting peripheral portion 17 extends around the periphery of the heat exchange plate, and within this there is a port portion 10a, located in one of the end planes of the plate, and a port portion 10b, located in the other end plane of the plate. The port portions 10a and 10b have throughflow ports 11a and 11b, respectively. Corresponding port portions located in said two end planes are provided at another end portion (not shown) of the heat exchange plate 2. Further there is a heat exchange portion 9, located between the port portions situated at each end of the heat exchange plate 2 having a corrugation pattern consisting of ridges and valleys, extending between said two end planes. Around the port 11a, situated in a lower end plane, there is an essential flat connecting area 12a, limited by an outer line 13a and an inner line 14a. Inside of the inner line 14a there is a number of projections 15a and outside of the outer line 13a there is a number of projections 16a. The projections 15a and 16a extend from the lower end plane to the said upper end plane. In a similar way, around the port 11b, located in the upper end plane, there is a connecting area 12b, limited by an outer line 13b and an inner line 14b. Likewise there is a number of projections 15b and 16b, which, however, extend from the upper end plane to the lower end plane.
The shown heat exchange plate 2 is intended to be joined with a similar heat exchange plate which has been rotated 180° in the plane of the plate. A heat exchange plate located behind the heat exchange plate 2 will abut against the rear side of the conneting area 12a and against the rear side of the projections 15b and 16b, and a heat exchange plate located in front of the heat exchange plate 2 will with its rear side abut against the connecting area 12b and against the projections 15a and 166.
Further the respective heat exchange plate located on each side of the heat exchange plate 2 will abut against respective side of the peripheral portion 17 and at a variety of points over the respective side of the heat exchange portion 9, since the ridges and valleys of the corrugation pattern for two adjacent heat exchange plates will cross each other.
In figure 3 there is shown an end portion of an end plate 3, comprising two non-penetrated port portions with stiffening projections 18 but which otherwise corresponds to the heat exchange plate 2 shown in figure 2. The stiffening projections 18 extend from the upper end plane to the lower end plane.
In figure 4 there is shown a cross-section through the plate heat exchanger 1 shown in figure 1, extending through the part of the heat exchanger comprising the second inlet pipe 6 and the first outlet pipe 7. This cross-section also corresponds to a corresponding cross-section through the first inlet pipe and the second outlet pipe of the heat exchanger.
The plate heat exchanger 1 comprises eight heat exchange plates 2, of the kind shown in figure 2, and a lower end plate 3 of the kind shown in figure 3, which are arranged above each other between the upper, outer cover plate 4a and the lower, outer cover plate 4b. The ports of the heat exchange plates are located in line with each other, so that they form an inlet channel and an outlet channel, which at the bottom are limited by the non-penetrated port portions of the end plate and which at the top communicate with the inlet pipe 6 and the outlet pipe 7 respectively. Two adjacent heat exchange plates 2 delimit a flow passage between the plates, depending on that the ridges of the corrugation pattern in the heat exchange portion of the plates cross each other. By that the connecting area 12b of one of the plates abuts against the connecting area 12a of the other plate said flow passage only communicates with either the inlet
channel or the outlet channel at respective end portion of the plates. Also the projections 15a and the projections 16a respectively, of one of the plates abut against the projections 15b and the projections 16b respectively, of the other plate.
The projections 15a and 15b abutting each other form connecting means 19, keeping together the port portions of the two heat exchange plates along the inlet and the outlet channels, respectively. The connecting means 19 along each of the inlet and outlet channels are located in the spaces between the plates which communicate with the inlet and the outlet channel respectively in an area located between the connecting areas 12a and 12b of the plates and the channel itself. Between the connecting means 19 in respective space between the plates there are openings 22 which communicate with the flow passage between the heat exchange plates. The lines 13 and 14 shown in figure 4, which delimit the connecting areas 12a and 12b of the plates, extend through the corresponding lines 13a and 13b and the lines 14a and 14b, respectively, as shown in figure 3.
In a similar way the projections 16a and 16b, abutting against each other, form connecting means 23, keeping together the port portions of the two adjacent heat exchange plates along the inlet and the outlet channel respectively. The connecting means 23 along each of the inlet and outlet channels is located in the spaces between the plates, which communicate with the inlet and the outlet channel, respectively, in an area which partly surrounds the inlet and the outlet channel, respectively, and which is located between the connecting areas 12a and 12b of the plates and adjacent parts of the peripheral portions 17 of the plates.
In the space between the upper cover plate 4a and the adjacent heat exchange plate 2, which appears either around the inlet channel or the outlet channel, there is a spacing ring 20 loca
ted in the connecting areas 12a and 12b respectively of the heat exchange plates 2. The spacing ring 20 also acts as a sealing between the heat exchange plate 2 and the cover plate 4a.
The end plate 3 located close to the lower cover plate 4b covers the inlet and outlet channels with its non-penetrated port portions and depending on the stiffening projections 18, abutting against the cover plate 4b, and the projections which correspond to the projections 15a and 15b of the heat exchange plates, a distance ring is not required between the cover plate 4b and the end plate 3.
The plate heat exchanger 1 according to the present invention comprises preferably heat exchange plates 2 with a rectangular form, but other forms could be possiblej as round heat exchange plates. The heat exchanger 1 is shown with one inlet channel and one outlet channel for each of the two heat exchange media, which inlet and outlet channels are located in the end portions of the heat exchange plates 2. A heat exchanger can of course be provided with several inlet or outlet channels. The shape of the channels and the location can be chosen freely.
The number of heat exchange plates 2 of the heat exchanger 1 is depending on desired capacity. For the joining of the heat exchanger a suitable amount of plates are piled on each other with solders in the shape of sheets placed between adjacent plates, whereupon the whole package is heated in an oven until said solders melt.
According to the present invention the connecting means 23 can, as an alternative, be formed of loose elements arranged between the heat exchange plates, but preferably the means 23 is formed as integral parts of respective heat exchange plates. The means 23 is formed of the projections 16a and 16b, which are pressed out from the port portions 10a and 10b, respectively, of the
heat exchange plates and which thereafter are permanently joined with corresponding projections of adjacent heat exchange plates.
To obtain a preferred distribution of the forces between the connecting means 23, being located in the different spaces between the plates, they are preferably arranged in line with each other perpendicularly against the heat exchange plates 2 along respective inlet and outlet channels.
The means 19 and 23 proposed according to the invention, also forms a guiding for the spacing ring 20, as shown in figure 4. This together with the circumstances that deformation of the port portions 10a and 10b, respectively, can be prevented during manufacture of the heat exchange plate 2, depending on the pressing out of the projections 15a and 15b, results in that the margine required for the areas 12a and 12b around the ports can be considerably reduced compared with the margine required in known heat exchangers. It is thus possible to provide the heat exchanger with connecting means 19 within the connecting areas 12a and 12b of the heat exchange plates without changing the size of the ports.
The inlet and outlet channels are open at one end of the heat exchange package and closed at the other end of the heat exchange package. It is suitable that the end plate 3 located at said other end has a port portion without any through-port. This non-penetrated port portion is provided with the space-giving and stiffening projections 18.