EP3786567A1

EP3786567A1 - An egr cooler

Info

Publication number: EP3786567A1
Application number: EP19382728.4A
Authority: EP
Inventors: José Antonio De La Fuente Romero; Eva Tomas Herrero; Teresa CONTE OLIVEROS
Original assignee: Valeo Termico SA
Current assignee: Valeo Termico SA
Priority date: 2019-08-26
Filing date: 2019-08-26
Publication date: 2021-03-03

Abstract

A heat exchanger is disclosed in accordance with an embodiment of the present invention. The heat exchanger includes housing, a heat exchanger core, a diverging tank and a baffle. The heat exchanger core is received in the housing and includes heat exchange tubes that receive hot gas. The coolant is received in the housing and around the heat exchange tubes. The diverging tank is disposed at a side of the housing and is diverging towards the housing. The diverging tank connects a coolant inlet with the housing to enable fluid communication between the coolant inlet and an interior of the housing. The baffle is disposed inside the diverging tank and divides interior of the diverging tank into at least two volumes, wherein at least one volume is in fluid communication with the interior of the housing and the baffle directs coolant flow to a gas inlet area inside the housing.

Description

The present invention relates to a heat exchanger, particularly to a thermal management system for an Exhaust Gas Re-circulation (EGR) cooler.

Background of the invention:

An Exhaust Gas Re-circulation (EGR) cooler receives exhaust gases from an engine and cools the exhaust gases before the exhaust gases are re-circulated back to the engine's cylinder. By re-circulating the engine's exhaust gas back to the engine's cylinder, the peak in-cylinder temperatures are regulated, specifically lowered to reduce formation of NOx gases. The EGR cooler further reduces the combustion chamber temperature, thereby preventing valve clatter, detonation and further reduces NO_x formation. As a result, the exhaust gas recirculation (EGR) system substantially reduces vehicle emissions to enable meeting stringent vehicular exhaust emission norms prevalent in most parts of the world.
In an EGR cooler, exhaust gas is received in a tank and from the tank the exhaust gas pass through heat exchange tubes received inside the housing, coolant is delivered by a coolant inlet pipe around the heat exchange tubes to cause heat exchange between the exhaust gas and the coolant, thereby resulting in cooling of the exhaust gas and reducing the temperature of the exhaust gas. The coolant inlet pipe is disposed at sidewall of the EGR cooler. The EGR cooler handles high temperature exhaust gases in the temperature range of 400 to 900 °C. Accordingly, temperatures at certain regions inside the EGR cooler, particularly, a gas inlet area of the heat exchange tubes that first comes into contact with the exhaust gas, exceeds acceptable limits and cause formation of hot spots. The hot spots at the gas inlet area cause problems such as boiling of the coolant, durability issues and excessive thermo-dynamical stresses at the gas inlet area. To avoid such problems, the coolant from the coolant inlet pipe is directed to the gas inlet area of the heat exchange tubes by using a baffle disposed inside the coolant inlet pipe to avoid high temperatures at the gas inlet area. However, such baffle extends inside the housing of the EGR cooler and interferes with the other components, particularly, components such as for example, heat exchange tubes disposed inside the housing of the EGR cooler. Further, packaging of the baffle within limited space inside the coolant inlet pipe is a concern and such configuration of the baffle inside the coolant inlet pipe may restrict coolant flow through the coolant inlet pipe. Further, conventional method of providing baffle for directing coolant to the gas inlet area through an inlet configured on the housing fails to effectively regulate distribution and velocity of coolant directed to the gas inlet area. Still further, the conventional baffle is a dedicated component and as such there are product costs, inventory costs and process costs associated with configuring the baffle.
Accordingly, there is need for an EGR cooler configured with a baffle that effectively directs coolant to the gas inlet area of the EGR cooler, thereby preventing high temperature hot spots at the gas inlet area and that is capable of addressing issues such as boiling of coolant, durability issues and excessive thermo-dynamical stresses arising due to hot spots at the gas inlet area of the EGR cooler. Further, there is a need for an EGR cooler configured with a baffle that does not interfere with the other components, particularly, components such as for example heat exchange tubes disposed inside the housing of the EGR cooler. Further, there is a need for an EGR cooler configured with a baffle that effectively directs coolant to the gas inlet area, thereby preventing excessive temperatures and the problems associated with the excessive temperatures at the gas inlet area. Further, there is a need for an EGR cooler configured with a baffle that is configured by modifying an existing part of the EGR cooler, thereby reducing product and process costs associated with configuring the baffle. Still further there is a need for an EGR cooler configured with a baffle inside a diverging tank secured to a side of housing of the EGR cooler, wherein the baffle can be conveniently packaged without disrupting coolant flow to heat exchange tubes received inside the housing, particularly, the gas inlet area. Further, there is a need for an EGR cooler that exhibits extended service life, improved reliability and efficiency.

Description of the invention:

An object of the present invention is to provide an EGR cooler that obviates the drawbacks associated with conventional methods for cooling a gas inlet area for an EGR cooler that fails to effectively regulate distribution and velocity of coolant directed to the gas inlet area.
Another object of the present invention is to provide an EGR cooler configured with a baffle that effectively directs coolant to a gas inlet area of an EGR cooler to achieve efficient cooling of the gas inlet area thereby addressing issues such as boiling of coolant, durability issues and excessive thermo-dynamical stresses arising due to hot spots at the gas inlet area of the EGR cooler.
Still another object of the present invention is to provide an EGR cooler configured with a baffle that does not interfere with the other components, particularly, components such as for example, heat exchange tubes disposed inside the housing of the EGR cooler.
Yet another object of the present invention is to provide an EGR cooler that can be easily packaged and that do not interfere with the flow of coolant through the coolant inlet pipe.
Still another object of the present invention is to provide an EGR cooler configured with a baffle that is configured by modifying an existing part of the EGR cooler, thereby reducing product, process and inventory costs associated with configuring the baffle.
Yet another objective of the present invention is to provide an EGR cooler that exhibits extended service life, improved reliability and efficiency.
In the present description, some elements or parameters may be indexed, such as a first element and a second element. In this case, unless stated otherwise, this indexation is only meant to differentiate and name elements which are similar but not identical. No idea of priority should be inferred from such indexation, as these terms may be switched without betraying the invention. Additionally, this indexation does not imply any order in mounting or use of the elements of the invention.
A heat exchanger is disclosed in accordance with an embodiment of the present invention. The heat exchanger includes housing, a heat exchanger core, a diverging tank and at least one baffle. The heat exchanger core is received in the housing and includes heat exchange tubes that receive hot gas. The coolant is received in the housing and around the heat exchange tubes. The diverging tank is disposed at a side of the housing and is diverging towards the housing. The diverging tank connects a coolant inlet with the housing to enable fluid communication between the coolant inlet and an interior of the housing. At least a portion of the at least one baffle is disposed inside the diverging tank and divides an interior of the diverging tank into at least two volumes, wherein at least one volume is in fluid communication with the interior of the housing and the at least one baffle directs coolant flow to a gas inlet area inside the housing.
Generally, the housing includes at least one inlet formed thereon for enabling fluid communication between the at least one volume of the diverging tank and the interior of the housing.
Particularly, the diverging tank includes a first opening connected to the coolant inlet and a second opening larger than the first opening and connected to the first opening, the second opening is so disposed with respect to said at least one inlet that said diverging tank covers said at least one inlet.
Generally, the at least one inlet and the at least one baffle is at least half the dimension of the second opening.
In accordance with an embodiment of the present invention, a base of the at least one baffle is disposed along at least a portion of a periphery of the at least one inlet.
Specifically, the at least one baffle forms an angle in the range of 20 to 70 degrees with respect to the side wall of the housing configured with the at least one inlet.
In accordance with an embodiment, the at least one baffle includes a plurality of tabs configured thereon to secure the at least one baffle inside the diverging tank.
Alternatively, the at least one baffle includes lips configured along at least a portion of a periphery thereof to secure the at least one baffle inside the diverging tank.
Further, the at least one baffle includes a plurality of apertures formed thereon.
Generally, the at least one baffle is integrally formed with the housing.
Specifically, the at least one baffle as well as the at least one inlet is formed by deforming a cut out portion of the housing that is integrally connected to the housing.
Preferably, the at least one baffle is of a shape selected from group of shapes comprising of rectangular, semi-circular and trapezoidal shape.
Generally, the heat exchange tubes are axially extending along the housing and the gas inlet area is near a tank delivering hot gases to the heat exchange tubes, the at least one inlet is disposed upstream of gas inlet area in direction of coolant flow and the at least one baffle directs coolant to the gas inlet area via the at least one inlet.
Other characteristics, details and advantages of the invention can be inferred from the description of the invention hereunder. A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying figures, wherein:

Brief description of the drawings:

FIG. 1a and FIG. 1b illustrate an EGR cooler in accordance with an embodiment of the present invention, particularly, a sectional view depicting internal details of a diverging tank disposed at a side wall of a housing of the EGR cooler;
FIG. 2a illustrates the baffle configured with tabs for securing the baffle to inner walls of the diverging tank of FIG. 1a and FIG. 1b ;
FIG. 2b - 2c illustrate different views of the diverging tank with the baffle of FIG. 2a received and secured inside the diverging tank;
FIGS. 2d- 2e illustrate different configurations of the baffle received inside the diverging tank, wherein the baffle is illustrated in different orientations with respect to an inlet configuring fluid communication between an interior of the diverging tank and an interior of the housing;
FIG. 2f illustrates the baffle received inside the diverging tank and in between two inlets configuring fluid communication between the interior of the diverging tank and the interior of the housing;
FIG. 3a illustrates the diverging tank of FIG.1 without the baffle received there inside;
FIG. 3b illustrates a sectional view of the diverging tank along the section line A-A of FIG 3a ;
FIG. 4a illustrates a baffle with a plurality of tabs formed thereon for securing the baffle inside the diverging tank;
FIG. 4b illustrates a baffle in accordance with another embodiment with apertures formed thereon; and
FIG 4c illustrates a baffle with lips formed thereon for securing the baffle inside the diverging tank.

It must be noted that the figures disclose the invention in a detailed enough way to be implemented, said figures helping to better define the invention if needs be. The invention should however not be limited to the embodiment disclosed in the description.

Detailed description of the preferred embodiments:

The present invention relates to a thermal management system for an Exhaust Gas Re-circulation (EGR) cooler, specifically to at least one baffle, hereafter simply referred to as a baffle disposed inside a diverging tank. Wherein a diverging tank is disposed at a side wall of a housing of the EGR cooler and is in addition to tanks disposed at ends of the housing for delivering hot gases to and collecting hot gases from heat exchange tubes received inside the housing. The baffle acts as a partition and divides an interior of the diverging tank into at least two volumes, wherein at least one volume is in fluid communication with an interior of the housing and the baffle directs coolant to a gas inlet area of the heat exchange tubes received inside the housing of the EGR cooler. Such configuration of the baffle, addresses issues such as boiling of coolant, durability issues and excessive thermo-dynamical stresses, arising due to hot spots forming at the gas inlet area of the EGR cooler. Although, the baffle of the present invention is used for directing coolant directly to the gas inlet area of the EGR cooler. However, the baffle of the present invention is also applicable for any other applications, where coolant or any other fluid is required to be directed at a particular region inside any other system such as for example a region that is exposed to hot fluid and that is required to be cooled to address issues arising due to formation of hot spots.
FIG. 1a and FIG. 1b illustrate a heat exchanger particularly, an EGR cooler 100 in accordance with an embodiment of the present invention. The EGR cooler 100 is configured with a diverging tank 30 disposed at a side wall 10a of a housing 10 of the EGR cooler 100, wherein the housing 10 receives a heat exchanger core 20. The diverging tank 30 is in addition to tanks (not illustrated) disposed at ends of the housing 10 for delivering hot gases to and collecting hot gases from a plurality of heat exchange tubes 22 received inside the housing 10. The diverging tank 30 is in fluid communication with a coolant inlet 12 at one end and the housing 10 at the other end, thereby enabling fluid communication between the coolant inlet 12 and an interior of the housing 10. The diverging tank 30 includes a baffle 14 that is at least partially received therein for directing coolant directly to a gas inlet area 16, such as for example portions of the heat exchange tubes 22 near inlet of the heat exchange tubes 22 and received inside the housing 10. The baffle 14 may also direct coolant to the areas adjacent to the gas inlet area 16 to prevent drawbacks associated with over-heating. The gas inlet area 16 is for example the portion of the heat exchange tubes 22 of the heat exchanger core 20 that first receive the exhaust gas and are first to come in contact with high temperature exhaust gases and as such is prone issues such as boiling of coolant, durability issues and excessive thermo-dynamical stresses arising due to formation of hot spots. With the baffle 14 directing coolant to the gas inlet area 16 disposed inside the housing 10 of the EGR cooler 100, the formation of hot spots at the gas inlet area 16 of the EGR cooler 100 is prevented and issues arising due to hot spots forming at the gas inlet area 16 of the EGR cooler 100 are also avoided. The baffle 14 may extend sideways out of the diverging tank 30 but do not extend into the housing 10 and as such do not interfere with the heat exchanger core 20 disposed inside the housing 10. The heat exchange tubes 22 are axially extending along the housing 10 and the gas inlet area 16 is near the tank delivering hot gases to the heat exchange tubes 22, the at least one inlet 18 is disposed upstream of gas inlet area 16 in direction of coolant flow and the at least one baffle 14 directs coolant to the gas inlet area 16 via the at least one inlet 18.
The housing 10 receives the heat exchanger core 20 connected to and disposed between a pair of headers disposed at the opposite ends of the housing 10. The heat exchanger core 20 includes the plurality of heat exchange tubes 22 that receive hot gas from the tank and through which the hot gas pass. The housing 10 further receives coolant around the heat exchange tubes 22 through the coolant inlet 12. Such an arrangement enables heat exchange between the hot gas flowing through the heat exchange tubes 22 and the coolant around the heat exchange tubes 22. The portion of the heat exchange tubes 22 that receives the exhaust gases and as such that first comes in contact with high temperature exhaust gases is the gas inlet area 16 that is prone to issues due to formation of hot spots.
The diverging tank 30 is disposed at side of the housing 10 and is diverging towards the housing 10. The diverging tank 30 receives at least a portion of the baffle 14 as illustrated in FIG. 2a . Referring to the FIG. 2b , the diverging tank 30 includes a first opening 30a connected to the coolant inlet 12 and a second opening 30b opposite to the first opening 30a, larger than the first opening 30a and connected to the first opening 30a by side walls of the diverging tank 30. The second opening 30b is further connected to the housing 10 along a flange 30c radially extending along the second opening 30b and as such the diverging tank 30 is diverging towards the housing 10. More specifically, the diverging tank 30 is disposed between the coolant inlet 12 and the housing 10, the second opening 30b of the diverging tank 30 is so disposed with respect to at least one inlet 18 formed on the housing 10 for configuring fluid communication between the diverging tank 30 and the interior of the housing 10, that the diverging tank 30 covers the at least one inlet 18. The diverging tank 30 is in fluid communication with the coolant inlet 12 and the housing 10, thereby enabling fluid communication between the coolant inlet 12 and the interior of the housing 10. Such configuration of the diverging tank 30 provides enough space for receiving the baffle 14. Accordingly, such configuration of the diverging tank 30 receiving the baffle 14 enables the baffle 14 to direct the coolant from the coolant inlet 12 to the gas inlet area 16 without disrupting coolant flow to the gas inlet area 16.
The baffle 14 is disposed inside the diverging tank 30 and acts as a partition to divide an interior of the diverging tank 30 into at least two volumes, wherein at least one volume is in fluid communication with the interior of the housing 10. The at least one baffle 14 forms an angle in the range of 20 to 70 degrees with respect to the side wall 10a of the housing 10 configured with the at least one inlet 18. FIG. 2a illustrates the baffle 14 configured with a plurality of tabs 14b for securing the baffle 14 to inner walls of the diverging tank 30. The baffle 14 can also be secured to the inner walls of the diverging tank 30 by using a plurality of lips 14d configured along at least a portion of periphery of the baffle 14 as illustrated in FIG. 4c . However, the present invention is not limited to any particular configuration of attachment means and method for securing the baffle 14 to inner walls of the diverging tank 30. FIGS. 2b - 2c illustrate different views of the diverging tank 30 with the baffle 14 received and secured inside the diverging tank 30.
In accordance with an embodiment as illustrated in FIGS. 2d and 2e , the two volumes are separated and isolated from each other by the baffle 14 and one of the two volumes is in fluid communication with the interior of the housing 10 via the inlet 18 formed on the housing 10. Specifically, FIGS. 2d- 2e illustrate different configurations of the baffle 14 received and secured inside the diverging tank 30, wherein the baffle 14 is illustrated in different orientations with respect to the inlet 18 configuring fluid communication between the interior of the diverging tank 30 and the interior of the housing 10. More specifically, a base 14a of the baffle 14 is disposed along at least a periphery of the at least one inlet 18 and the baffle 14 can be at any angle, for example, angle "α" with the outside wall or the side wall 10a of the housing 10. Preferably, the baffle 14 is at an acute angle with respect to the side wall 10a of the housing 10. Further, the inlet 18 formed on the housing 10 can be of different dimensions "D1" and "D2". In accordance with an embodiment, the inlet 18 and the baffle 14 is at least half the dimension of the second opening 30b. The orientation of the baffle 14 and the dimension of the inlet 18 formed on the housing 10 are based on the position of the gas inlet area 16 with respect to the inlet 18, and particularly, based on the direction in which the coolant is to be directed to reach the gas inlet area 16 and amount of coolant to be supplied to the gas inlet area 16 for effective cooling of the gas inlet area 16.
In accordance with another embodiment as illustrated in FIG. 2f , the two volumes are in fluid communication with each other. Further at least one of the two volumes are in fluid communication with the interior of the housing 10 via at least one of the inlets 18. Specifically, both volumes are in fluid communication with the interior of the housing 10 via inlets 18 formed on the housing 10 and illustrated in FIG. 2f , wherein one inlet supplies coolant to the gas inlet area 16, such as for example portions of the heat exchange tubes 22 near the inlet of the heat exchange tubes 22, whereas the other inlet 18 supplies coolant to the remaining portion of the heat exchange tubes 22. The baffle 14 directs coolant to the gas inlet area 16 inside the housing 10 via one of the inlets 18.
In one embodiment of the present invention, the baffle 14 is of a planar configuration. In accordance with another embodiment, the baffle 14 is an integral part of the housing 10, particularly, integral part of the side wall 10a of the housing 10. More specifically, the at least one baffle 14 as well as the at least one inlet 18 is formed by deforming a cut out portion of the housing 10 that is still connected to the housing 10. The cut out portion of the housing 10 is cut along a profile and is configured by stamping operation such that the cut out portion is still connected to the side wall 10a of the housing 10 along at least one edge of the cut out portion, wherein when the cut out portion is lifted away from the side wall 10a to form the inlet 18 on the side wall 10a, the lifted cutout portion acts as the baffle 14. More specifically, the baffle 14 can have different shapes such as rectangular, semi-circular and trapezoid shape, with at least one edge connected to the housing 10. However, the present invention is not limited to any particular shape of the cut out portion or the baffle 14 formed thereby and any particular method for forming the cut out portion until the cut out portion is capable of being deformed for forming the at least one baffle 14 as well as the at least one inlet 18 simultaneously. With such configuration the at least one baffle 14 and the at least one inlet 18 are formed by a single step, thereby reducing the number of manufacturing steps required for configuring the diverging tank 30 secured to the housing 10 and with the at least one baffle 14 and the at least one inlet 18 received there inside.
As the baffle 14 in accordance of the present invention is formed by modifying an existing part of the EGR cooler, particularly, by modifying the housing 10, product, process and inventory costs associated with configuring the baffle as a dedicated element are eliminated. Further, with such configuration of the baffle 14, the baffle 14 is disposed inside the diverging tank 30 and does not interfere with the other components, particularly, components such as heat exchange tubes disposed inside the housing 10 of the EGR cooler 100. In accordance with another embodiment, the baffle 14 includes a plurality of apertures 14c configured thereon. The present invention is not limited to any particular placement of the apertures 14c on the baffle 14. The baffle 14 is formed by deforming the cut out portion of the housing 10, particularly, the cut out portion from the side wall 10a of the housing 10, such that the periphery of the cut out portion snugly fits with respect to inner walls of the diverging tank 30. However, the present invention is not limited to any particular shape, configuration and orientation of the baffle 14 inside the diverging tank 30 and method of forming the baffle 14 as far as the baffle 14 is capable of effectively directing coolant to the gas inlet area 16 disposed inside the housing 10. FIG. 3a illustrates the diverging tank 30 without the baffle 14 received there inside. FIG. 3b illustrates a sectional view of the diverging tank 30 along the section line A-A of FIG. 3a .
Several modifications and improvement might be applied by the person skilled in the art to the heat exchanger and such modifications and improvements will still be considered within the scope and ambit of the present invention, as long the heat exchanger includes housing, a diverging tank and a baffle. The housing receives a heat exchanger core that includes heat exchange tubes that receives hot gas. The diverging tank is disposed at a side of the housing and is diverging towards the housing. The diverging tank connects a coolant inlet with the housing to enable fluid communication between the coolant inlet and an interior of the housing. The baffle is disposed inside the diverging tank and divides interior of the diverging tank into at least two volumes, wherein at least one volume is in fluid communication with the interior of the housing and the baffle directs coolant flow to a gas inlet area inside the housing.
In any case, the invention cannot and should not be limited to the embodiments specifically described in this document, as other embodiments might exist. The invention shall spread to any equivalent means and any technically operating combination of means.

Claims

A heat exchanger (100) comprising:
• a housing (10);

• a heat exchanger core (20) adapted to be received in said housing (10) and comprising heat exchange tubes (22) that are adapted to receive hot gas, coolant is received in said housing (10) and around said heat exchange tubes (22);

• a diverging tank (30) disposed at a side of said housing (10) and diverging towards said housing (10), said diverging tank (30) adapted to connect a coolant inlet (12) with said housing (10) to enable fluid communication between said coolant inlet (12) and an interior of said housing (10); and

• at least a portion of at least one baffle (14) disposed inside said diverging tank (30) and adapted to divide an interior of said diverging tank (30) into at least two volumes, wherein at least one volume is in fluid communication with said interior of said housing (10) and said at least one baffle (14) is adapted to direct coolant flow to a gas inlet area (16) inside said housing (10).
The heat exchanger (100) as claimed in previous claim, wherein said housing (10) comprises at least one inlet (18) formed thereon for enabling fluid communication between said at least one volume of said diverging tank (30) and said interior of said housing (10).
The heat exchanger (100) as claimed in the claim 2, wherein said diverging tank (30) comprises a first opening (30a) connected to said coolant inlet (12) and a second opening (30b) larger than said first opening (30a) and connected to the first opening (30a), said second opening (30b) is so disposed with respect to said at least one inlet (18) that said diverging tank (30) covers said at least one inlet (18).
The heat exchanger (100) as claimed in the claim 2, wherein said at least one inlet (18) and said at least one baffle (14) is at least half the dimension of said second opening (30b).
The heat exchanger (100) as claimed in the claim 2, wherein a base (14a) of said at least one baffle (14) is disposed along at least a portion of a periphery of said at least one inlet (18).
The heat exchanger (100) as claimed in the previous claim, wherein said at least one baffle (14) forms an angle "α" in the range of 20 to 70 degrees with respect to a side wall (10a) of said housing (10) configured with said at least one inlet (18).
The heat exchanger (100) as claimed in any of the preceding claims, wherein said at least one baffle (14) comprises a plurality of tabs (14b) configured thereon and adapted to secure said at least one baffle (14) inside said diverging tank (30).
The heat exchanger (100) as claimed in any of the preceding claims, wherein said at least one baffle (14) comprises lips (14d) configured along at least a portion of a periphery thereof and adapted to secure said baffle (14) inside said diverging tank (30).
The heat exchanger (100) as claimed in any of the preceding claims, wherein said at least one baffle (14) further comprises a plurality of apertures (14c) formed thereon.
The heat exchanger (100) as claimed in any of the preceding claims, wherein said at least one baffle (14) is integrally formed with said housing (10).
The heat exchanger (100) as claimed in any of the preceding claims, wherein said at least one baffle (14) as well as the at least one inlet is formed by deforming a cut out portion of said housing (10) that is integrally connected to said housing (10).
The heat exchanger (100) as claimed in any of the preceding claims, wherein said at least one baffle (14) is of a shape selected from group of shapes comprising rectangular, semi-circular and trapezoidal shape.
The heat exchanger (100) as claimed in any of the claim 2, wherein said heat exchange tubes (12) are axially extending along said housing (10) and said gas inlet area (16) is near a tank delivering hot gases to said heat exchange tubes (22), said at least one inlet (18) is disposed upstream of gas inlet area (16) in direction of coolant flow and said at least one baffle (14) is adapted to direct coolant to said gas inlet area (16) via said at least one inlet (18).