US3817324A

US3817324A - Heat exchanging plate

Info

Publication number: US3817324A
Application number: US00299643A
Authority: US
Inventors: J Lund
Original assignee: Alfa Laval AB
Current assignee: Alfa Laval AB
Priority date: 1972-10-24
Filing date: 1972-10-24
Publication date: 1974-06-18
Anticipated expiration: 1991-06-18

Abstract

Each side of the plate has two distribution surfaces provided with pressed ridges extending side-by-side from an inlet hole and an outlet hole, respectively, to a centrally located main heat exchanging surface, the back sides of the troughs between the ridges forming the ridges on the opposite side of the plate. The troughs are wider than the ridges, so as to reduce the flow resistance along each distribution surface; but this width difference is less at those regions of the distribution surface which are close to said main surface than at other regions of the distribution surface, whereby the contact areas formed by crossing and abutting ridges of adjacent plates in a heat exchanger are greater at said close regions where they must transmit greater forces.

Description

United States Patent [191 Andersson [451 June 18, 1974 HEAT EXCHANGING PLATE [75] Inventor: .Jarl Anders Andersson, Lund,

Sweden [73] Assignee: Alia-Laval AB, Tumba, Sweden [22] Filed: Oct. 24, 1972 21 Appl. No.: 299,643

[52] US. Cl. 165/167 [51] Int. Cl F28f 3/02 [58] Field of Search 165/166, 167

[56] References Cited UNITED STATES PATENTS 2,787,446 4/1957 Ljungstrom 165/167 3,532,161 10/1970 Lockel 165/167 FOREIGN PATENTS OR APPLICATIONS 1,048,122 11/1966 Great Britain 165/166 913,291 6/1954 Germany 165/166 Primary Examiner-Charles .I. Myhre Assistant Examiner-Theophil W. Streule, Jr. Attorney, Agent, or FirmCyrus S. Hapgood [57] ABSTRACT Each side of the plate has two distribution surfaces provided with pressed ridges extending side-by-side from an inlet hole and an outlet hole, respectively, to a centrally located main heat exchanging surface, the back sides of the troughs between the ridges forming the ridges on the opposite side of the plate. The troughs are wider than the ridges, so as to reduce the flow resistance along each distribution surface; but this width difference is less at those regions of the distribution surface which are close to said main surface than at other regions of the distribution surface, whereby the contact areas-formed by crossing and abutting ridges of adjacent plates in a heat exchanger are greater at said close regions where they must transmit greater forces;

2 Claims, 4 Drawing Figures HEAT EXCHANGING PLATE The present invention relates to a heat exchanging plate of the kind having on each side a centrally located heat exchanging surface and distribution surfaces situated between the heat exchanging surface and an inlet and an outlet, respectively, for a heat exchanging medium intended to flow across the respective side of the plate. More particularly, the invention relates to such a plate having on its distribution surfaces of one plate side pressed ridges which extend side-byside from the inlet or outlet to the heat exchanging surface and which define troughs having a greater width than the ridges, the ridges being adapted to cross and abut the underneath or back sides of troughs in the distribution surfaces of a similar adjacent plate in a plate heat exchanger.

One purpose of the distribution surfaces is to offer a minimum of flow resistance for a heat exchanging medium on its way to and from the centrally located or main heat exchanging surface of the plate. For this reason it is desired that the ridges of the distribution surfaces be as narrow as possible and that the troughs extending therebetween, which are intended for the flow of the heat exchanging medium, be as wide as possible. However. a practical consideration which limits this desired dimensioning is the requirement of a certain strength of the heat exchanging plate. The greater the width of the troughs relative to the width of the ridges, the less the ability of the plate to resist deformation in transmitting forces created at the contact points in a plate heat exchanger between the back sides of the troughs of the plate and the ridges of an adjacent plate.

The principal object of the present invention is to provide for even wider troughs between the ridges, in a plate of the above-noted kind, than has been possible heretofore without causing a corresponding reduction in the strength of the plate.

According to the invention, this object is fulfilled by an arrangement wherein the difference between the width of the ridges and the width of the troughs is made smaller in the areas close to the main heat exchanging surface of the plate than in other parts of the distribution surfaces. With the ridges and the troughs thus formed, the ability of the plate to transmit forces without deformation will be greater in these areas than in the other parts of the distribution surfaces. This varying ability of transmitting forces (i.e., varying across the distribution surfaces) meets the present requirements for these areas. That is, since heat exchanging plates of this kind are generally free from ridges or other support means adapted to contact adjacent plates (in a plate heat exchanger) in the portions of the main heat exchanging surface adjacent the distribution surfaces, the contact points located on the distribution surfaces close to the main heat exchanging surface will have the further burden of transmitting the forces caused by the pressures of the heat exchanging media acting on these plate portions which are free of ridges or other direct support means. By the invention, substantially an optimum configuration of the distribution surfaces of a heat exchanging plate is achievable to provide the greatest possible difference between the width of the ridges and the width of the troughs across the distribution surfaces, so that the heat exchanging media will meet a minimum of flow resistance on their way to and from the main heat exchanging surface of the plate.

The invention will be described below with reference to the accompanying drawing, in which FIG. 1 is a schematic plan view of a plate of the kind involved here,

FIG. 2 is a detailed plan view of part of a prior art plate,

FIG. 3 is a view similar to FIG. 2 but illustrating a preferred embodiment of the invention, and

FIG. 4 is a sectional view on line lV-lV in FIG. 2.

In FIG. 1 there is shown a heat exchanging plate having a centrally located main heat exchanging surface 1 which borders on

distribution surfaces

2 and 3 located at opposite end portions of the plate. The two dot-dash lines C indicate the border lines between the heat exchanging surface 1 and the two

distribution surfaces

2 and 3. The

distribution surfaces

2 and 3 are situated between themain heat exchanging surface 1 and an inlet 4 and an outlet 5, respectively, for a heat exchanging medium which is intended to flow across the illustrated side of the plate within an area confined by a gasket 6. Across the opposite side of the plate, another heat exchanging medium is intended to flow from an inlet 7 to an outlet 8 within an area confined by a gasket 9. As will be readily understood by those skilled in the art, the

gaskets

6 and 9 are adapted to seal against adjacent plates in a heat exchanger to provide the usual plate interspaces, there being additional gaskets (not shown) individually surrounding the plate holes 7 and 8 on the illustrated side of the plate and the

plate holes

4 and 5 on the opposite side of the plate.

The flow lines for the heat exchanging medium which will flow across the illustrated side of the plate are indicated by arrows 10. As can be seen, these flow lines have different lengths. To prevent certain parts of the heat exchanging medium from being heated or cooled substantially more than others, it has long been known to fonn the

distribution surfaces

2 and 3 so that they offer a flow resistance which is very small in relation to that offered by the main heat exchanging surface 1 of the plate.

In FIG. 2 there is shown part of a distribution surface of a prior art plate in which several ridges 11 are pressed. These ridges extend in spaced parallel relation from the inlet or outlet for the heat exchanging medium to the main heat exchanging surface of the plate. As shown in FIG. 2, the ridges 11 are oriented to extend along distribution surface 2 from inlet 4 in FIG. 1, it being understood that the corresponding ridges on distribution surface 3 will be differently oriented to extend from the main surface 1 to outlet 5. Between the ridges 11 there are formed troughs 12, the underneath or back sides of which form ridges on the opposite side of the plate (FIG. 4). As can be seen, the troughs 12 are substantially wider than the ridges 11 for facilitating the flow of the heat exchanging medium across the distribution surface. It is desirable that the troughs 12 be even wider, so that the flow resistance offered by the distribution surfaces to the heat exchanging medium can be further reduced. However, widening of the troughs 12 is impossible with prior plates of this kind, owing to the strength requirements of the plates. The wider the troughs 12 are, the less the back sides of them will be able to resist pressure from a crossing ridge in an adjacent plate without being deformed.

In FIG. 2, there are shown two

contact areas

13 and 14 between the back sides of two troughs 12 of the plate and one ridge 11a of a plate situated behind the illustrated plate in a plate heat exchanger. The force acting at the contact area 14, at a certain pressure difference between the two heat exchanging media, will be larger than the corresponding force acting at the contact area 13. This is due to the fact that the spacing between the contact area 14 and the nearest contact area on the plates main heat exchanging surface 1 (not shown in FIG. 2), i.e., on the other side of the line C in FIG. 2, is greater than the spacing between two contact areas both located within the distribution surface. This nearest contact area on the main heat exchanging surface is not shown, but it has this greater spacing due to the previously mentioned portions of the plate which are free from ridges or other support means, such portions being indicated by the areas between each line C in FIG. 1 and the adjacent line C. It will be understood that the plate surface 1 between the two lines C in FIG. 1 is formed with ridges or other protuberances (not shown) which may be arranged in a conventional pattern for promoting turbulence of the flow and providing supporting contacts between adjacent plates in the heat exchanger.

Due to this condition described in connection with FIG. 2, the troughs 12 in the distribution surfaces of prior plates have been made only so wide that they can transmit the forces created at the contact points 14 without being deformed. As a result, the distribution surfaces have been stronger than necessary at the other contact points, where the forces to be transferred are smaller.

In FIG. 3, showing part of a plate formed according to the present invention, the ridges 11 in the distribution surface of the plate are provided with enlargements 15 at their ends close to the main heat exchanging surface of the plate. Thus, the contact areas obtained in this part of the distribution surface between the back sides of the troughs l2 and the crossing ridges l1a.of an adjacent plate in a heat exchanger will be larger than corresponding contact areas obtained with the prior plate shown in FIG. 2. As a result, the back sides of the troughs 12 will be able to resist a greater pressure from the crossing ridges of the adjacent plate in these areas than in other partsof the distribution surface. There is shown in FIG. 3 a contact area 16 which is thus enlarged due to the enlargements l5 and which is formed between the back side of a trough I2 of the plate and a ridge 11a of a plate situated behind it.

The advantage of a distribution surface configuration as shown in FIG. 3 can be utilized in different ways. Either the troughs 12 may be made wider than heretofore between the inlet or outlet opening in the distribution surface and the enlargements 15 of the ridges, or a greater pressure difference between the heat exchanging media in the plate heat exchanger can be allowed. A third possibility is to make the plates of a thinner material.

Because the enlargements 15 are situated at the ends of the troughs l2, i.e., immediately adjacent the main heat exchanging surface of the plate, the distribution surfaces can distribute the heat exchanging medium across the whole width of the main heat exchanging surface in the best possible manner, which would not be the case if the ridges 11 were made wider at any other part of the distribution surfaces.

1 claim:

1. For use in a plate heat exchanger, a heat exchanging plate having a main heat exchanging portion and two distribution portions, said three portions forming on each side of the plate a centrally located main heat exchanging surface and two distribution surfaces separated by said main surface, each distribution surface on one of the plate sides having pressed ridges extending side-by-side to said main surface from a remote part of the plate and also having troughs formed between the ridges, said troughs being wider than the ridges and being operable to direct a heat exchanging medium to and from said main surface, the ridges being arranged to cross and abut the back sides of the troughs in the distribution surfaces of a similar adjacent plate in a plate heat exchanger, the plate being characterized in that the difference between the width of the ridges and the width of the troughs is smaller at the regions of the distribution surfaces which are close to said main surface than at other regions of said distribution surfaces.

2. A heat exchanging plate according to claim 1, in which the end portions of the ridges adjacent said main surface are enlarged to effect said smaller difference.