WO2010134869A1

WO2010134869A1 - A plate heat exchanger

Info

Publication number: WO2010134869A1
Application number: PCT/SE2010/050430
Authority: WO
Inventors: Perola Magnus Helin; Johan GÅRDMO; Rolf Christensen
Original assignee: Alfa Laval Corporate AB
Current assignee: Alfa Laval Corporate AB
Priority date: 2009-05-18
Filing date: 2010-04-21
Publication date: 2010-11-25
Anticipated expiration: 2011-11-18
Also published as: SE533783C2; SE0950353A1

Abstract

A plate heat exchanger comprises a plate package (1) with heat exchanger plates (2) forming primary plate interspaces (3) for a primary medium and secondary plate interspaces (4) for a secondary medium. A primary inlet (11) transports the primary medium into the primary plate interspaces. A primary outlet (12) transports the primary medium out of the primary plate interspaces. A secondary inlet (21) transports the secondary medium into the secondary plate interspaces. A secondary outlet (22) transports the secondary medium out of the secondary plate interspaces. A sensor device (30) comprises a closed space (31) containing a sensor medium influenced by the temperature of the secondary medium. A throttle member (35) connected to the sensor device controls the flow of the primary medium in response to the sensor medium. The space is formed by a closed plate interspace (3') adjoining at least one adjoining one (4') of the secondary plate interspaces. The plate heat exchanger comprises flow-reducing means arranged to reduce the flow of the secondary medium through the adjoining one of the secondary plate interspaces.

Description

A plate heat exchanger

THE BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention refers to a plate heat exchanger according to the preamble of claim 1.

EP-B-608 195 discloses such a plate heat exchanger with a sensor device comprising a temperature sensor with an elongated shape. The temperature sensor extends in one of the port channels of the plate heat exchanger, which communicates with some of the heat transfer passages of the plate package. The temperature sensor communicates with a valve for controlling a flow of for instance district heat water through the plate heat exchanger.

DK-U-9600205 discloses a similar plate heat exchanger provided with a space that is provided outside the plate heat exchanger and extends at an outer surface of the plate heat exchanger. An elongated temperature sensor is provided in the space. The space communicates with passages for one of the fluids in the plate heat exchanger. The space is provided in the proximity of one inlet or outlet opening of the heat exchanger. The temperature sensor is arranged to cooperate with equipment for controlling a flow of one of the fluids through the plate heat exchanger.

These documents thus suggest the provision of a separate sensor outside the plate heat exchanger or in any of the port channels of the plate heat exchanger. The provision of such a separate sensor is difficult from a manufacturing point of view. Furthermore, a sen- sor in any of the port channels results in an increased flow resistance, not only due to the sensor itself, but also due to the components required for attaching the sensor in the port channel. US-B-7, 152,663 discloses a similar plate heat exchanger where these problems at least partly have been solved. In one of the disclosed embodiments, the closed space of the sensor device is formed by two of the heat exchanger plates in the plate package. In such a way, the closed space may be provided in a very close heat transferring contact with one or both of the media. Consequently, possibilities are created for obtaining a large contact surface of the sensor device. With a large contact surface a large drive force for for instance a control valve, the valve position of which is controlled by means of the sensor medium, is achieved.

A problem which is not solved in an optimum manner with the plate heat exchanger disclosed in US-B-7, 152,663 is that the sensor device may result in a too large control deviation on the secondary side when operation changes arise. The solution disclosed in US-B- 7,152,663 does not ensure that the sensor device in an optimum manner may sense a temperature of the secondary medium which is representative for the desired temperature of the secondary medium.

A further problem in this context is that the temperature profile along the plate interspaces may be such that it is difficult to achieve a representative and proper temperature sensing of the sensor device. If the sensor medium comprises for instance a gaseous phase and a liquid phase, the result of the temperature influencing on the sensor device will be different at the different phases. Due to the fact that the border between the gaseous phase and the liquid phase is not located at a constant level, the controlling may be problematic. The temperature influencing on the gaseous phase re- suits in a relatively smaller pressure increase of the sensor medium than the temperature influencing on the liquid phase. If the gaseous phase with a significant part is located in the area where the secondary medium has a high temperature, this temperature may rise without obtaining a sufficient pressure increase of the sensor me- dium, and thus also no sufficient influencing on the control member. SUMMARY OF THE INVENTION

The object of the present invention is to remedy the above mentioned problems, and to provide a plate heat exchanger with an im- proved sensor device ensuring a proper and uniform control of the temperature of the secondary medium.

This object is achieved by the plate heat exchanger initially defined, which is characterized in that the space is formed by a closed plate interspace, which adjoins an adjoining one of the secondary plate interspaces, and that the plate heat exchanger comprises flow- reducing means arranged to reduce the flow of the secondary medium through the adjoining secondary plate interspace.

By means of such a reducing of the flow, or the flow quantity, the temperature of the secondary medium in the adjoining secondary plate interspace, which adjoins the closed space, will increase. It is with such a reducing possible to provide the same, or substantially the same temperature profile on the secondary medium in the ad- joining secondary plate interspace as in the remaining secondary plate interspaces.

According to an embodiment of the invention, the closed plate interspace is located outermost in the plate package at the rear side, wherein the adjoining secondary plate interspace forms an outermost secondary plate interspace.

According to an embodiment of the invention, the flow-reducing means comprises a throttling arranged to throttle the flow of the secondary medium. Advantageously, the throttling may be provided in the porthole of the heat exchanger plate that adjoins the adjoining secondary plate interspace and the adjoining one of the primary plate interspaces. Furthermore, the throttling may be provided in this heat exchanger plate in the porthole that forms a part of the secondary inlet port channel or the secondary outlet port channel. According to an embodiment of the invention, the flow-reducing means comprises a reduced thickness of the adjoining secondary plate interspace in relation to the thickness of the remaining secondary plate interspaces.

According to a further embodiment, each heat exchanger plate has a heat transfer surface with a corrugation, wherein the flow- reducing means, as a supplement or an alternative, may comprise a modification of the corrugation of the heat transfer surface of at least one of the heat exchanger plates that delimits the adjoining secondary plate interspace in comparison with the corrugation of the remaining heat exchanger plates.

According to an embodiment of the invention, the adjoining secon- dary plate interspace communicates with the secondary inlet and the secondary inlet port channel, and the secondary outlet and secondary outlet port channel.

According to an embodiment of the invention, the closed plate inter- space is closed in relation to the primary inlet port channel and the primary outlet port channel by means of closed portholes in the heat exchanger plate that adjoins the closed plate interspace.

According to an embodiment of the invention, the plate heat ex- changer comprises a front side plate which is located at the front side and adjoins an outermost heat exchanger plate. Advantageously, the primary inlet port channel, the primary outlet port channel, the secondary inlet port channel and the secondary outlet port channel may extend through the front side plate.

According to an embodiment of the invention, the throttle member comprises an influencing member which is connected to the space and arranged to influence the throttle member by sensing a pressure change of the secondary medium in the space. According to an embodiment of the invention, the throttle member is arranged to control the flow of the primary medium through the primary plate interspaces in response to the sensor medium.

BRIEF DESCRIPTION OF THE DRAWINGS.

The present invention is now to be explained more closely through a description of various embodiments and with reference to the drawings attached hereto.

Fig 1 discloses schematically a front view of a plate heat exchanger according to the invention.

Fig 2 discloses schematically a side view through the plate heat exchanger according to a first embodiment of the invention along the line M-Il in Fig 1.

Fig 3 discloses schematically a side view through the plate heat exchanger according to the first embodiment along the line Ill-Ill in Fig 1.

Fig 4 discloses schematically a side view through the plate heat exchanger according to a second embodiment of the invention along the line H-Il in Fig 1.

Fig 5 discloses schematically a side view through the plate heat exchanger according to the second embodiment along the line IV-IV in Fig 4.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

Figs 1-3 disclose a plate heat exchanger comprising a plate package 1 with a plurality of heat exchanger plates 2, which are com- pression-moulded in a manner known per se and comprise a heat transfer surface 2' with a compression-moulded corrugation 2" of ridges and valleys, schematically indicated in Fig 1. The heat ex- changer plates 2 are provided beside each other in the plate package in such a way that they form primary plate interspaces 3 for a primary medium and secondary plate interspaces 4 for a secondary medium, see Figs 2 and 3. The primary and secondary plate inter- spaces 3 and 4 are provided in an alternating order in the plate package 1 , i.e. every second plate interspace is a secondary plate interspace 4.

The plate heat exchanger disclosed is particularly configured for an application in a local heating network, or a district heating network, for instance for heating of tap water, wherein the primary medium is district heating water from a central district heating plant and the secondary medium is tap water to be heated by the district heating water in the plate heat exchanger. In the heating network, any heat source can be used, for instance a heating plant, an oil heater, a sun heating plant etc. It is to be noted, however, that the plate heat exchanger according to the invention can be used also in other applications, for instance for cooling, in heating pump plants, in industrial processes, for cooling and/or heating in vehicles etc.

The plate package 1 has a first end Y and a second opposite end 1", and a front side 5 and an opposite rear side 6. A front side plate 7 is provided outermost at the front side 5, and may be formed by an outermost heat exchanger plate 2 or a plane plate provided out- side but preferably against the outermost heat exchanger plate 2. The plate heat exchanger may also comprise a corresponding rear side plate 8 which is provided outermost at the rear side 6, and which may be formed by the outermost heat exchanger plate 2 or by a plane plate provided outside but preferably against the outermost heat exchanger plate 2.

In the embodiments disclosed, the heat exchanger plates 2 are permanently connected to each other through for instance brazing, gluing, or welding. Preferably, also the front side plate 7, and pos- sibly the rear side plate 8, are permanently connected to the heat exchanger plates 2 through for instance brazing, gluing or welding. The front side plate 7 and the rear side plate 8 may then form a part of the plate package 1. However, it is to be noted that the invention also is applicable to plate heat exchangers which are kept together in any other way, such as by means of tie bolts.

The plate heat exchanger comprises a primary inlet 11 and a primary outlet 12 for the primary medium, and a secondary inlet 21 and a secondary outlet 22 for the secondary medium, see Figs 1 and 3.

The primary inlet 1 1 is arranged to transport the primary medium into the plate package 1 to the primary plate interspaces 3. The primary inlet 1 1 comprises a primary inlet port channel 13 extending through at least a part of the plate package 1. The primary inlet port channel 13 is formed by a porthole through each of the heat ex- changer plates 2 except for some of the heat exchanger plates 2 as can be seen more closely below. The primary inlet 11 comprises an external inlet pipe 15 in line with the primary inlet port channel 13.

The primary outlet 12 is arranged to transport the primary medium out from the plate package 1 from the primary plate interspaces 3. The primary outlet 12 comprises a primary outlet port channel 14 extending through at least a part of the plate package 1. The primary outlet port channel 14 is formed by a porthole through each of the heat exchanger plates 2 except for some of the heat exchanger plates 2 as can be seen more closely below. The primary outlet 12 comprises an external outlet pipe 16 in line with the primary outlet port channel 14.

The secondary inlet 21 is arranged to transport the secondary me- dium into the plate package 1 to the secondary plate interspaces 4. The secondary inlet 21 comprises a secondary inlet port channel 23 extending through at least a part of the plate package 1. The secondary inlet port channel 23 which is formed by a porthole through each of the heat exchanger plates 2 except for some of the heat ex- changer plates 2 as can be seen more closely below. The secondary inlet 21 comprises an external inlet pipe 25 in line with the secondary inlet port channel 23. The secondary outlet 22 is arranged to transport the secondary medium out from the plate package 1 from the secondary plate interspaces 4. The secondary outlet 22 comprises a secondary outlet port channel 24 extending through at least a part of the plate pack- age 1. The secondary outlet port channel 24 is formed by a porthole through each of the heat exchanger plates 2 except for some of the heat exchanger plates 2 as can be seen more closely below. The secondary outlet 22 comprises an external outlet pipe 26 in line with the secondary outlet port channel 24.

The primary inlet port channel 13, the primary outlet port channel 14, the secondary inlet port channel 23 and the secondary outlet port channel 24 thus extend through the front side plate 7, i.e. outwardly from the front side 5 via the respective external inlet and outlet pipes 15, 16, 25 and 26.

The plate heat exchanger comprises a sensor device 30, which comprises a space 31 which is closed in relation to the primary plate interspaces 3 and in relation to the secondary plate inter- spaces 4. The space 31 contains a sensor medium which is provided to be influenced by the temperature of the secondary medium. The sensor medium may advantageously comprise or consist of a substance which is in a gaseous phase and liquid phase at the temperature and at the pressure prevailing in the space 31. The sensor medium may for instance comprise or consist of carbon dioxide and active carbon or a gas-liquid mixture.

The space 31 is defined by two of the heat exchanger plates 2 or by one of the heat exchanger plates 2 and one of the rear side plate 8 or the front side plate 7. In the embodiments disclosed, the space 31 is formed by a closed plate interspace 3¹ which adjoins an adjoining one 4¹ of the secondary plate interspaces 4, through which the secondary medium flows. The closed plate interspace 3¹ is thus located outermost in the plate package 1 at the rear side 6. The ad- joining secondary plate interspace 4' is located immediately inside the space 31 and secondly outermost of the plate interspaces 3, 4 with the respect to the rear side 6. The adjoining secondary plate interspace 4' thus forms the outermost secondary plate interspace. As can be seen in Fig 2, the adjoining one of the secondary plate interspaces 4 communicates with the secondary outlet 22 and the secondary outlet port channel 24. As can be seen in Fig 3, the closed plate interspace 3' is closed in relation to the primary inlet port channel 13 and the primary outlet port channel 14.

The plate heat exchanger is connected to or comprises throttle member 35 which is connected to the sensor device 30. The throttle member 35 is in the embodiments disclosed arranged to control the flow of the primary medium through the primary plate interspaces 3 in response to the sensor medium. However, it is to be noted that the throttle member 35 may be arranged to control the flow of the secondary medium through the secondary plate interspaces 4 in re- sponse to the sensor medium. The throttle member 35 may be realised in the form of a valve of any suitable design. In the embodiments disclosed, the throttle member 35 is provided on the external outlet pipe 16 to the primary outlet 12, but it may also be provided on the external inlet pipe 15 to the primary inlet 1 1.

The throttle member 35 comprises an influencing member 36 which is connected to the space 31 via a conduit 37, for instance an electric conduit or a capillary tube configured to transfer a pressure change in the space 31 to the influencing member 36. The influenc- ing member 36 is arranged to influence the throttle member 35 by sensing a pressure change of the sensor medium in the space 31. The pressure of the sensor medium is depending on the temperature. An increase of the temperature of the secondary medium leads to an increase of the pressure of the sensor medium which via the influencing member 36 increases the throttling of the throttle member 35 so that the flow of the primary medium is reduced. In a corresponding manner, a decrease of the pressure of the sensor medium leads to a decrease of the pressure of the sensor medium which via the influencing member 36 decreases the throttling of the throttle member 35 so that the flow of the primary medium increases. In a cooling application, the influencing member 36 is inverted so that an increase of the temperature of the secondary me- dium leads to an increase of the pressure of the sensor medium which via the influencing member 36 decreases the throttling of the throttle member 35 so that the flow of the primary medium increases.

The plate heat exchanger also comprises flow-reducing means arranged to reduce the flow of the secondary medium through the adjoining one of the secondary plate interspaces 4. By such a reduction of the flow, or the flow quantity, the temperature of the secon- dary medium in the adjoining secondary plate interspace 4' will increase. In such a way, substantially the same temperature profile on the secondary medium is achieved in the adjoining secondary plate interspace 4' as in the remaining secondary plate interspaces 4.

According to the first embodiment disclosed especially in Figs 2 and 3, the flow-reducing means comprises a throttling 40 which is arranged to throttle the flow of the secondary medium. As can be seen in Fig 2, the throttling 40 is provided in one of the portholes of the heat exchanger plate 2 that adjoins the adjoining secondary plate interspace 4' and the adjacent one of the primary plate interspaces 3. More precisely, the throttling 40 is provided in this heat exchanger plate 2 in the porthole located in or forming a part of the secondary inlet port channel 23.

It is to be noted that it is possible, as a supplement or alternative, to provide the throttling 40 in this heat exchanger plate 2 in the porthole located in or forming a part of the secondary outlet port channel 24.

According to a further alternative it is possible to provide the throttling 40 in any suitable position in the adjoining outermost plate interspace 4'.

Figs 4 and 5 disclose a second embodiment of the plate heat exchanger according to the invention. It is to be noted that the same or similar elements have been provided with the same reference signs in the embodiments disclosed. The second embodiment differs from the first embodiment in that the flow-reducing means, instead of a throttling, comprises a thickness of the adjoining secondary plate interspace 4\ which thickness is reduced in relation to the thickness of the remaining secondary plate interspaces 4. As can be seen in Figs 4 and 5, the adjoining secondary plate interspace 4', which adjoins the closed plate interspace 3', has a thickness which is significantly thinner than the thickness of the remaining secondary plate interspaces 4. For instance, the adjoining sec- ondary plate interspace 4' may have a thickness which is half of the thickness, or substantially half of the thickness, of the remaining secondary plate interspaces 4. The reduction of the thickness of the adjoining secondary plate interspace 4', or depth, can be provided through a reduced press depth during the compression-moulding of this heat exchanger plate 2, i.e. the heat exchanger plate 2 that adjoins the adjoining one of the secondary plate interspaces 4 and the adjacent one of the primary plate interspaces 3.

As an alternative or supplement, the throttling can be increased by a modification of the corrugation 2" of the heat transfer surface 2' of one or both of the heat exchanger plates 2 that delimit the adjoining secondary plate interspace 4' in comparison with the corrugation 2" of the remaining heat exchanger plates 2. In such a way, the flow resistance in the adjoining secondary plate interspace 4' may be increased.

The invention is not limited to the embodiments disclosed but may be varied and modified within the scope of the following claims.

It is possible to let the space 31 within the scope of the invention be located in a closed plate interspace 3' which is located within the plate package 1 , preferably between two secondary plate interspaces.

In the embodiments disclosed, the plate heat exchanger is configured for counter flow flowing of the primary medium and the secondary medium. It is possible to configure the plate heat exchanger according to other flowing principles, such as parallel flowing or flowing in the same direction.

Furthermore, the primary inlet port channel 13 and the primary out- let port channel 14 may be located diagonally and not straight above each other as disclosed in the figures. The same is of course also valid for the secondary inlet port channel 23 and the secondary outlet port channel 24.

It is to be noted that the flow-reducing means also may comprise a combination of two or more of the above defined embodiments thereof.

Claims

1. A plate heat exchanger comprising a plate package (1 ) with a plurality of heat exchanger plates (2), which are provided beside each other in the plate package (1 ) in such a way that they form primary plate interspaces (3) for a primary medium and secondary plate interspaces (4) for a secondary medium, which primary and secondary interspaces (3, 4) are provided in an alternating order in the plate package (1), wherein the plate package (1 ) has a first end (V) and a second opposite end (V)₁ and a front side (5) and an opposite rear side (6), a primary inlet (1 1), which is arranged to transport the primary medium into the plate package (1 ) to the primary plate interspaces (3) and comprises a primary inlet port channel (13), a primary outlet (12), which is arranged to transport the primary medium out from the plate package (1 ) from the primary plate interspaces (3) and comprises a primary outlet port channel (14), a secondary inlet (21 ), which is arranged to transport the secondary medium into the plate package (1) to the secondary plate inter- spaces (4) and comprises at least a secondary inlet port channel (23), a secondary outlet (22), which is arranged to transport the secondary medium out from the plate package (1 ) from the secondary plate interspaces (4) and comprises a secondary outlet port channel (24), a sensor device (30), which comprises a space (31 ) which is closed in relation to the primary plate interspaces (3) and the secondary plate interspaces (4), wherein the space (31) contains a sensor medium which is provided to be influenced by the temperature of the secondary medium, and a throttle member (35), which is connected to the sensor device (30) and arranged to control the flow of one of the primary medium and the secondary medium in response to the sensor medium, characterized in that the space (31) is formed by a closed plate interspace (3'), which adjoins at least one adjoining (4') one of the secondary plate interspaces (4) and that the plate heat exchanger comprises flow reduc- ing means arranged to the reduce the flow of the secondary medium through the adjoining secondary plate interspace (4').

2. A plate heat exchanger according to claim 1 , wherein the closed plate interspace (3') is located outermost in the plate package (1 ) at the rear side (6), wherein the adjoining secondary plate interspace (4') forms an outermost secondary plate interspace.

3. A plate heat exchanger according any one of claims 1 and 2, wherein the flow reducing means comprises a throttling (40) arranged to throttle the flow of the secondary medium.

4. A plate heat exchanger according to claim 3, wherein the throttling (40) is provided in a porthole of the heat exchanger plate (2) that adjoins the adjoining one of the secondary plate interspaces (4) and the adjoining one of the primary plate interspaces (3).

5. A plate heat exchanger according to claim 4, wherein the throttling (40) is provided in the porthole that forms a part of the secondary inlet port channel (23) or the secondary outlet port channel (24).

6. A plate heat exchanger according to any one of the preceding claims, wherein the flow-reducing means comprises a reduced thickness of the adjoining secondary plate interspace (4¹) in relation to the thickness of the remaining secondary plate interspaces (4).

7. A plate heat exchanger according to any one of the preceding claims, wherein each heat exchanger plate (2) has a heat transfer- ring surface (2') with a corrugation (2") and wherein the flow- reducing means comprises a modification of the corrugation (2") of the heat transferring surface (2') of at least one of the heat exchanger plates (2) that limits the adjoining secondary plate interspace (4') in comparison with the corrugation (2") of the remaining heat exchanger plates (2).

8. A plate heat exchanger according to any one of the preceding claims, wherein the adjoining secondary plate interspace (4') communicates with the secondary inlet (21 ) and the secondary inlet port channel (23), and the secondary outlet (22) and the secondary out- let port channel (24).

9. A plate heat exchanger according to any one of the preceding claims, wherein the closed plate interspace (3') is closed in relation to the primary inlet port channel (13) and the primary outlet port channel (14) by means of closed portholes in the heat exchanger plate (2) that adjoins the closed plate interspace (3').

10. A plate heat exchanger according to any one of the preceding claims, wherein the plate heat exchanger comprises a front side plate (7), which is located at the front side (5) and adjoins an outermost heat exchanger plate (2).

11. A plate heat exchanger according to claim 10, wherein the primary inlet port channel (13), the primary outlet port channel (14), the secondary inlet port channel (23) and the secondary outlet port channel (24) extend through the front side plate (7).

12. A plate heat exchanger according to any one of the preceding claims, wherein the throttle member (35) comprises an influencing member (36) which is connected to the space (31) and arranged to influence the throttle member (35) by sensing a pressure change of the sensor medium in the space (31 ).

13. A plate heat exchanger according to any one of the preceding claims, wherein the throttle member (35) is arranged to control the flow of the primary medium through the primary plate interspaces (3) in response to the sensor medium.