Abstract
A plate heat exchanger without straight flow channels is provided, for exchanging heat between fluids. Said heat exchanger, comprises a start plate, an end plate and a number of heat exchanger plates provided with a pressed pattern of ridges and grooves with a pitch. The heat exchanger plates are kept at a distance from each other by contact between ridges and grooves of neighboring plates in contact points, when said plates are being stacked onto one another. Flow channels are thus formed between said plates, the contact points are positioned so that no straight lines are formed along the length of the heat exchanger plates.
Claims
1. A plate heat exchanger for exchanging heat between fluids, comprising: (a) a start plate, an end plate, and a number of heat exchanger plates arranged between the start plate and the end plate, the heat exchanger plates being provided with a pressed pattern of ridges and grooves, wherein the heat exchanger plates include a first pair of port openings, a second pair of port openings, and a length extending from the first pair of port openings to the second pair of port openings, and forming flow channels between neighboring heat exchanger plates such that flow in the channels is from one of the first pair of port openings to one of the second pair of port openings or vice versa; (b) the pressed pattern of ridges and grooves are arranged in an inclined straight pattern or a curved pattern, wherein a pitch of the pressed pattern of ridges and grooves varies over the length of the heat exchanger plates forming a varied pitch extending from the first pair of port openings to the second pair of port openings, and wherein the pitch is a distance along a plane parallel to the heat exchanger plates between adjacent ridges and grooves; and (c) said heat exchanger plates form contact points between the pressed pattern of ridges and grooves of neighboring heat exchanger plates, wherein the contact points between the pressed pattern of ridges and grooves of neighboring heat exchanger plates form a curve in a plane parallel to the heat exchanger plates and through the contact points, and wherein the curve results from the varied pitch of the pressed pattern of ridges and grooves, wherein the contact points along the length of the heat exchanger plates provide that the flow channels are not straight.
2. The heat exchanger of claim 1, wherein the varied pitch of the pressed pattern increases over said length.
3. The heat exchanger of claim 2, wherein the varied pitch of the pressed pattern increases according to an arithmetic series.
4. The heat exchanger of claim 1, wherein the ridges and grooves are distributed in groups defined by portions of ridges and grooves with smaller pitch, separated by portions with larger pitch.
5. The heat exchanger of claim 1, wherein the varied pitch of the ridges and grooves of the pressed pattern is different in different parts over the length of the heat exchanger plates.
6. The heat exchanger of claim 1, wherein the pressed pattern of ridges and grooves extending between the first pair of port openings and the second pair of port openings is provided as only the inclined straight pattern.
7. The heat exchanger of claim 1, wherein the pressed pattern of ridges and grooves extending between the first pair of port openings and the second pair of port openings is provided as only the curved pattern.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In the following, the invention will be described with reference to the appended drawings, wherein:
(2) FIG. 1 is a schematic top view of two prior art heat exchanger plates;
(3) FIG. 2a is a schematic top view of two heat exchanger plates with a varying pitch of the pressed pattern of ridges and grooves;
(4) FIG. 2b is a schematic top view showing contact points between two heat exchanger plates comprised in the present invention;
(5) FIG. 3a is a schematic top view of two heat exchanger plates with varying pitch;
(6) FIG. 3b is a schematic top view showing two heat exchanger plates wherein the pitch increases arithmetically over the length of the heat exchanger plates;
(7) FIG. 4a is a schematic top view of a heat exchanger plate according to the present invention;
(8) FIGS. 4b and 4c are section views taken along the line A-A of FIG. 4a;
(9) FIG. 5a is a schematic top view of a heat exchanger plate with partly varying pitch and a herringbone pattern of ridges and grooves;
(10) FIG. 5b is a schematic top view of a heat exchanger plate with partly varying pitch and a pattern of straight inclined ridges and grooves;
(11) FIG. 6a is a schematic top view of a heat exchanger plate with partly grouped herringbone pattern of ridges and grooves;
(12) FIG. 6b is a schematic top view of a heat exchanger plate with partly grouped pattern of straight inclined ridges and grooves;
(13) FIG. 7a is a schematic top view of a heat exchanger plate with different pitch of herringbone shaped ridges and grooves in different parts of the length of the heat exchanger plates;
(14) FIG. 7b is a schematic top view of a heat exchanger plate with different pitch of straight inclined ridges and grooves in different parts of the length of the heat exchanger plates; and
(15) FIGS. 8a and 8b are schematic top views of heat exchanger plates with curved pattern of ridges and grooves.
DESCRIPTION OF EMBODIMENTS
(16) An example of a prior art heat exchanger is seen in FIG. 1, described in the prior art chapter.
(17) In FIGS. 2a and 2b, two top views exhibiting a contact point pattern between two heat exchanger plates comprised in a heat exchanger 100 according to a first embodiment of the present invention are shown. The heat exchanger 100 comprises a number of heat exchanger plates 110, which each comprises a pressed herringbone pattern of ridges 120 and grooves 130, adapted to form flow channels between neighboring plates as the plates are stacked onto one another, wherein one plate has been rotated 180 degrees in its plane compared to its neighbours. The herringbone shape of the pressed pattern is necessary if identical plates are used for the heat exchanger. Moreover, the heat exchanger plates comprise port openings 140, being in fluid communication with the flow channels in a way well known to a person skilled in the art. The contact points between the ridges 120 and grooves 130 of neighboring heat exchanger plates are positioned so that no straight lines joining the contact points are formed along the length of the heat exchanger plates 110—se lines curved lines CP of FIG. 2b.
(18) In FIGS. 3a and 3b, an embodiment exhibiting one heat exchanger plate 110′ and one neighboring heat exchanger plate 110″ is shown. The heat exchanger plate 110′ is placed above the heat exchanger plate 110″. The heat exchanger plates 110′, 110″ are provided with a pressed pattern of ridges 120′, 120″, respectively, and grooves 130′, 130″, respectively. The patterns of ridges and grooves are adapted to keep the heat exchanger plates on a distance from one another, by contact between ridges 120′, 120″ and grooves 130′, 130″ of the neighboring heat exchanger plates, when stacked onto one another. The port openings 140′, 140″ are provided on different heights, in a way well known by persons skilled in the art; by placing the port openings on various heights, it is possible to provide ports allowing fluid flow into one space delimited by a pair of heat exchanger plates, and sealing off fluid flow into other spaces delimited by another, often neighboring space delimited by heat exchanger plates 110′, 110″.
(19) The resulting heat exchanger 100 will hence exhibit flow channels for the heat exchanging fluid held together by contact points between ridges and grooves, positioned such that straight flow through the flow channels is made impossible, i.e. heat exchanging channels where the first and second fluid media flow in a more turbulent fashion. In most cases, this is highly desired. However, the desired degree of turbulence created may vary from case to case.
(20) An advantage with this is that the heat exchanging fluid is flowing in a more turbulent fashion, which gives a more efficient heat transfer.
(21) In FIGS. 4a and 4b, an embodiment exhibiting the non linearity more clearly is shown. In FIG. 4a arrows A-A indicate a section through the heat exchanger plate 110, which section is shown in FIG. 4b. A distance X of the smallest pitch between a ridge 120a and a groove 130a is less than the distance X+Y of the next pitch between a ridge 120b and a groove 130b, which in turn is less than the distance X+Z of the following pitch between a ridge 120c and a groove 130c. When combining two heat exchanger plates 110, turned 180 degrees in relation to each other, the contact points between the ridges 120 and grooves 130 of neighboring heat exchanger plates are positioned so that no straight lines are formed along the length of the heat exchanger plates 110.
(22) In FIGS. 5a and 5b, an embodiment exhibiting the pitch of the pressed pattern of the heat exchanger plate 110 varying over a first part 500 of the length of the heat exchanger plate 110, while being constant over a second part 510 of the length of the heat exchanger plate 110 is shown. The length of the heat exchanger plate 110 may also be divided in more than two parts, with alternating varying and constant pitch. The length of the heat exchanger plate 110 may be subdivided into parts with alternating varying and constant pitch according to any ratio suitable, such as 50/50, 70/30, 30/70, 33/33/33, 25/25/50 etc.
(23) In an embodiment according to FIGS. 6a and 6b, the ridges and grooves are distributed in groups defined by portions of ridges and grooves with smaller pitch 600, separated by portions with larger pitch 610. Any number of ridges and grooves may be used in the groups defined by portions of ridges and grooves with smaller pitch 600, such as 2, 3, 4, 5, 6, 7, 8 ridges and grooves.
(24) In FIGS. 7a and 7b, an embodiment exhibiting the pitch of the pressed pattern of the heat exchanger plate 110, constant over a first part 700 of the length of the heat exchanger plate 110 and different over a second part 710 of the length of the heat exchanger plate 110, is shown. The length of the heat exchanger plate 110 may also be divided into more than two parts, with pitches of different value. The length of the heat exchanger plate 110 may be subdivided into parts according to the embodiment shown in FIGS. 5a and 5b.
(25) Different patterns of the ridges and grooves may be used to keep the heat exchanger plates at a distance from each other when the ridges and grooves of neighboring heat exchanger plates interact in contact points, when said heat exchanger plates are being stacked onto one another so that the contact points are positioned so that no straight flow channels are formed. In the embodiments according to FIG. 5a, FIG. 6a and FIG. 7a, a herringbone pattern is used. In the embodiments according to FIG. 5b, FIG. 6b and FIG. 7b, a pattern with inclined straight lines is used. In further embodiments according to FIGS. 8a and 8b, a curved pattern is used. Any possible combination of distances between the ridges and grooves or any possible grouping or distribution of ridges and grooves may be used in combination with any pattern, as long as the contact points obtained when stacking the heat exchanger plates, with or without rotating them 180 degrees, are positioned so that no straight flow channels are formed.
(26) The heat exchanger plates may be fixed to each other by any means known to a person skilled in the art, such as brazing, pressing, etc.
(27) The present invention can be varied significantly without departing from the scope of invention, such as it is defined in the appended claims.
