Heat exchanger

Abstract

A heat exchange apparatus 10 comprises a first housing 12 defining an inlet chamber 40 which receives a gaseous fuel flow and a second housing 14 defining an outlet chamber 58. A gas flow pipe 21 is i

Description

FIELD OF THE INVENTION This invention relates to a heat exchanger for gaseous fuel. In particular, but not exclusively, the invention relates to a heat exchanger for use in a fuel system of an internal combustion engine for a gaseous fuel such as hydrogen. BACKGROUND Gaseous fuels such as hydrogen are promising alternative fuels to gasoline and diesel due to their potential for low or zero emissions and there has been considerable interest in developing traditional internal combustion engines to run on ecologically produced hydrogen. Research into the feasibility of this solution suggests that injecting hydrogen at a pressure considerably higher than atmospheric pressure beneficially affects engine efficiency. As a consequence, a compressor system is required to locate between the hydrogen tank of the vehicle and the fuel injection system itself. The compressor system acts on the fuel within the tank and elevates the pressure to a suitable pressure for injection to optimize efficiency. However, an effect of having to use a compressor on the gaseous fuel is that there is a rise in its temperature, so that a heat mechanism is needed to extract the required heat from the fuel before it can be used in the injection system. It is an object of the invention to provide a heat exchange apparatus for this purpose. SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a heat exchange apparatus for a gaseous fuel flow, the heat exchange apparatus comprising an inlet chamber defined within a first housing arranged at one end of the heat exchange apparatus, the inlet chamber configured to receive a gaseous fuel flow and communicating with a gas flow pipe for receiving the gaseous fuel flow and for delivering the gaseous fuel flow to an outlet chamber defined within a second housing, wherein the gas flow pipe extends through a coolant chamber for receiving a coolant which flows around the gas flow pipe to extract heat from the gas flow pipe, wherein the inlet chamber is provided with at least one contaminant separation feature to separate contaminants within the gaseous fuel flow from the gaseous fuel to prevent onward passage through the gas flow pipe. The at least one contaminant separation feature encourages contaminants within the gaseous fuel flow to separate from the gaseous fuel and to fall toward the floor of the inlet chamber to prevent onward passage through the gas flow pipe. The heat exchange apparatus may include a plurality of gas flow pipes for optimum cooling. The apparatus provides a convenient means for cooling a flow of hydrogen gas after it has been compressed and the temperature is elevated. The separation of contaminants from the gas flow ensures the cooling is achieved efficiently, and does not require the use of a filter within the inlet chamber. The heat exchange apparatus may comprise a first contaminant separation feature comprising an inlet nozzle for directing a jet of gaseous fuel flow into the inlet chamber to generate a vortex flow within the inlet chamber. As the gaseous flow is directed into the inlet chamber, the flow is directed in a spiral motion around the walls of the inlet chamber which causes contaminants such as oil to separate from the main gaseous flow. Reducing or avoiding contaminants flowing onwards through the gas pipes provides a cooling efficiency advantage. The heat exchange apparatus may comprise an insert arranged within the inlet chamber for dividing the inlet chamber into an entry portion and an exit portion, wherein the insert is provided with an in-chamber nozzle for allowing gaseous fuel to pass between the entry portion and the exit portion. The in-chamber nozzle may comprise a flared entry channel. The flared entry channel tends to encourage any separated contaminants to attach to the flared surface to prevent them rejoining the gaseous flow and flowing onwards through the gas flow pipe(s). The insert within the inlet chamber may comprise a disc. The insert may be provided with an opening to allow contaminants to pass between the entry portion the exit portion of the inlet chamber in a lower region of the inlet chamber. The inlet nozzle may be configured to direct the jet of gaseous fuel flow into the entry portion of the inlet chamber. The heat exchange apparatus may comprise a second contaminant separation feature comprising a flared collar which projects into the entry portion of the inlet chamber. The flared collar may be carried by a plug carried by and / or secured within the first housing. The flared collar may for example flare outwardly into the inlet chamber from a relatively smaller diameter region to a relatively larger diameter region of the collar, wherein the relatively larger diameter region projects further into the inlet chamber. The shape of the flared collar serves to encourage any oil droplets within the inlet gaseous away from the entry channel into the exit portion. The heat exchange apparatus may comprise an outlet port which communicates with the inlet chamber through a floor of the inlet chamber to allow exit of separated contaminants from the gaseous fuel flow. The heat exchange apparatus may comprise a plurality of gas flow pipes supported by a plurality of baffles arranged within the coolant chamber. The inlet chamber may comprise an outlet port provided in a floor of the inlet chamber to allow exit of separated contaminants from the gaseous fuel flow. The outlet chamber may comprise an outlet port provided in a floor of the outlet chamber to allow exit of separated contaminants from the gaseous fuel flow. The heat exchange apparatus may comprise a first seal between the inlet chamber and the coolant chamber to prevent mixing of gaseous fuel and coolant and / or a second seal between the coolant chamber and the outlet chamber to prevent mixing of gaseous fuel and coolant. The heat exchange apparatus may comprise a filter arranged within the outlet chamber for capturing contaminants remaining within the gaseous flow before exiting the heat exchange apparatus. The heat exchange apparatus may comprise an intermediate housing for defining the coolant chamber, and wherein the first housing and the intermediate housing are mounted together by means of one or more studs and / or wherein the second housing and the intermediate housing are mounted together by means of one or more studs. BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood, preferred non-limiting embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross section view of an embodiment of the heat exchange apparatus of the invention; Figure 2 is a perspective view of an inlet end section of the heat exchange apparatus in Figure 1; Figure 3 is an enlarged cross section view of the inlet end of the heat exchange apparatus in Figure 1; Figure 4 is an enlarged view of a part of the inlet end in Figure 3; Figure 5 is a perspective view, from a first side, of an inlet disc forming part of the heat exchange apparatus in Figure 1; Figure 6 is a perspective view, from a second side, of the inlet disc in Figure 5; Figure 7 is a cross section of the inlet end of the heat exchange apparatus, taken along plane F-F in Figure 3; Figure 8 is a perspective view of an outlet end section of the heat exchange apparatus, at the opposite end to that shown in Figure 2; Figure 9 is a perspective view of an outlet disc forming part of the outlet end section in Figure 7; and Figure 10 is a cross section view, similar to Figure 1, of an alternative embodiment of the heat exchange apparatus. Throughout this description, terms such as ‘left and ‘right, and other directional references, are used with reference to the orientation of the compressor system as shown in the accompanying drawings. However, it will be appreciated that such references are not limiting and that compressor systems according to the invention can be used in any orientation. DETAILED DESCRIPTION OF THE INVENTION Figures 1 to 9 illustrate a heat exchange apparatus (or heat exchanger) 10, and component parts thereof, according to an embodiment of the invention. The heat exchange apparatus 10 is intended for use downstream of a compressor (not shown) for gaseous fuel in a fuel system for an engine (not shown), where the compressor is provided to pressure the hydrogen gas to a level considerably higher than atmospheric pressure to benefit engine efficiency. The compressor itself forms part of a fuel delivery system that is configured to deliver gaseous fuel from a fuel tank (not shown) to a fuel injection system (not shown) and, from there, to the internal combustion engine. However, compressors with which the heat exchange apparatus 10 may be used also have application outside the context of a vehicle, for example in fuelling stations. The heat exchanger 10 includes a first housing part 12 and a second housing part 14 arranged at opposite ends of the apparatus 10. The first housing (also referred to as the “first head”) 12 is at the right hand end if the arrangement and is essentially identical to the second housing 14 (also referred to as the “second head”) at the left hand end of the arrangement. The heads 12, 14 are connected together via an intermediate housing part 16 in the form of a cylinder between the two heads 12,14. The first head 12 forms an inlet end section of the heat exchanger 10 and the second head 14 forms an outlet end section of the heat exchanger 10. The heat exchanger 10 has a longitudinal axis A-A. An inlet end discharge port 18 is provided in a lower portion of the first head 12 to allow contaminants such as oil that is carried by the gaseous fuel into the heat exchanger 10 to exit the heat exchanger once it has been separated from the gaseous flow, as discussed further below. An outlet end discharge port 19 is provided in a lower portion of the second head 14 to allow contaminants such as oil to exit the heat exchanger if they do happen to flow through to the second head 14, as discussed further below. The cylinder 16 defines an internal coolant volume 20 of the heat exchanger which allows the gas to be cooled to pass through the apparatus. A coolant inlet channel 22 is formed in the first head 12 to deliver coolant to the internal coolant volume. A coolant outlet channel 24 is formed in the second head 14 to allow coolant to exit the coolant volume 20 once it has passed through. An array of gas flow pipes 21 extends through the coolant volume 20, with respective ends of the gas flow pipes projecting from the ends of the coolant volume 20 and extending into the first and second heads 12, 14 where they are supported by respective first and second supports 26, 28 which define the end walls of the coolant volume 20. The gas flow pipes 21 form a cluster or bundle of pipes extending along the longitudinal axis A-A. Studs 30 are provided on each of the first and second heads 12, 14 to secure the heads to the cylinder. The configuration of the first and second heads 12, 14, the intermediate cylinder 16 and the studs 30 to secure the parts together provide a convenient means of dismantling the apparatus 10 for servicing, if required. In an alternative embodiment the intermediate cylinder 16 may comprise two welded flanges that allow the cylinder 16 to be clamped to the first and second head 12, 14. First and second annular seals, 32, 34 respectively, are provided on the radially outer periphery of each of the first and second supports 26, 28, to prevent contamination between gaseous fuel and coolant. Third and fourth annular seals 36, 38 are also provided between the intermediate cylinder 16 and each of the first and second heads, 12, 14 respectively, to prevent coolant leaking from the internal coolant chamber 20 past the seals 36, 38. An inlet chamber 40 is defined within the first head 12 into which gaseous fuel is introduced from the heat exchanger 10. A drilling 42 opens into the inlet chamber 40 to define a gas inlet to the inlet chamber. As best seen in Figure 2, the inlet chamber 40 comprises two portions; an entry portion 44 of relatively narrower diameter about the axis A-A and an exit portion 46 of relatively larger diameter about the axis A-A. The entry and exit portions 44, 46 are separated by means of an insert in the form of an inlet disc 48. The entry portion 44 of the inlet chamber 40 has a variable depth measured along the axis A-A of the heat exchanger. The variable depth is achieved through profiling the end wall 49 of the entry portion 44 so that the length of the central region 50 of the entry portion 44, which is aligned with the axis A-A, is shallower than the length of the radially outer region 52 of the entry portion 44. The exit portion 46 defines an inlet manifold for the gas flow pipes 21. Gaseous fuel which is introduced to the inlet chamber 40 is able to flow through the gas flow pipes 21 and into an outlet chamber 58 (shown in Figure 8) defined within the second head 14, from where it exits the heat exchanger apparatus 10 having been cooled. The second head 14 is provided with an outlet (not shown), similar to the inlet 42 in the first head 12, to allow the gas flow to exit the apparatus 10. Coolant is introduced into the coolant volume 20 through a coolant inlet 22 defined within the first head 12 and is able to exit the coolant volume 20 through the coolant outlet 24 defined within the second head 14. It is a notable feature of the heat exchanger 10 that it is the gaseous fuel which is to be cooled that flows through the pipes 21, with the coolant surrounding the pipes 21 within the coolant chamber 20, rather than having the coolant flowing through the pipes 21 as in a conventional heat exchange apparatus. The gas flow pipes 21 are supported by baffles 6-OA, 70A, 80A (three of which are shown in Figure 1) arranged within the coolant volume 20. The baffles 60A, 70A, 80A provide support for the gas flow pipes 21 to prevent buckling of the pipes 21 and also to increase the heat transfer to coolant by spacing apart the pipes 21. A greater or lesser number of baffles to those shown may be arranged within the coolant volume 20, depending on the length of the heat exchanger 10. Each baffle 60A, 70A, 80A comprises a plurality of relatively small openings, through each of which a gas pipe extends, and a relatively large opening through which a group of three gas pipes passes through, together with the coolant flowing around the pipes. In the cross section view of Figure 1, five gas flow pipes of the gas flow network 21 are shown, although it will be appreciated that any number of gas flow pipes 21 may be used depending on the heat exchanger requirements and the desired size of the heat exchanger, amongst other things. Starting from the upper side of the heat exchanger 10, the gas flow pipes which are visible in the plane are numbered 1 to 5 in Figure 2, with gas pipe 1 being the uppermost pipe, gas pipe 5 being the lowermost pipe and gas pipe 3 being the central pipe. The first, second and third baffles 60A, 70A, 80A are spaced axially from one another along the axis A-A of the heat exchanger 10 and extend perpendicular to the axis A-A between an upper part of the internal wall of the cylinder 16 and a lower part of the internal wall of the cylinder 16. The first and second supports 26, 28 and the three baffles 60A, 70A, 80A are equi-distantly spaced along the axis A-A to provide optimum support for the gas pipe network. In this configuration, the second baffle 70A is positioned centrally between the first and second supports 26,28. For the first baffle 60A, the relatively large opening in the baffle is positioned so that gas pipes 3, 4 and 5 pass therethrough with gas pipes 1 and 2 extending through the relatively smaller holes in the first baffle 60A. Likewise, for the third baffle, the relatively large opening in the baffle is positioned so that gas pipes 3, 4 and 5 pass therethrough with gas pipes 1 and 2 extending through the relatively smaller holes in the third baffle 80A. For the second baffle 70A, the relatively large opening in the baffle is positioned so that gas pipes 1, 2 and 3 pass therethrough, with gas pipes 4 and 5 extending through the relatively smaller holes in the second baffle 70A. The second baffle 70A is therefore configured differently to the first and third baffles 60A, 80A. The gas flow pipes 21 form a bundle of pipes with inlet ends communicating with the inlet chamber 40 and outlet ends communicating with the outlet chamber 58 (the gas pipe network is best illustrated in Figure 8). The baffles are configured around the gas flow pipes 21 to ensure that there is adequate support for the pipes 21, but that coolant is able to freely flow around the gas pipes 21 also. The configuration of baffles 60A, 70A, 80A provides adequate support for the gas flow pipes 21 within the coolant chamber 20, but also leaves a flow path around the pipes 21 to ensure coolant can flow freely along the axial length of the heat exchanger 10, between the coolant inlet 22 and the coolant outlet 24. The first head 12, the configuration of the inlet chamber 40 in the first head 12, and the communication path to the gas flow pipes 21, will now be described in further detail. As shown in Figures 5 and 6, the inlet disc 48 comprises a planar disc element 48a and an annular rim 48b which forms an upstand at the periphery of the planar disc 48a. The inlet disc 48 is mounted within the exit portion 46 of the inlet chamber 40 and the annular rim 48b has a diameter which matches the outer diameter of the exit portion 46. An in-chamber nozzle 90 is formed in the centre of the inlet disc 48 to define an opening 92 to allow gaseous fuel to flow through the inlet disc 48, between the entry and exit portions 44, 46 of the inlet chamber 40, and into the inlet ends of the gas flow pipes 21. The exit portion 46 of the inlet chamber 40 therefore defines a gas inlet manifold for the gas pipes 21. The gas inlet 42 to the inlet chamber 40 is best seen in Figure 7 and comprises a main inlet drilling 110 having a stepped diameter and a jet nozzle 112 at the outlet end which communicates with the entry portion 44 of the inlet chamber 40. The jet nozzle 112 together with the inlet chamber 40 form a first contaminant separation feature of the heat exchanger 10 due to a vortex flow being generated within the inlet chamber 40, as a result of the jet nozzle 112, forcing oil droplets within the gaseous flow to separate from the main flow and fall to the floor of the inlet chamber 40. In more detail, the gaseous fuel entering the inlet chamber 40 through the jet nozzle 112 is accelerated into a spiral motion (as shown by the dashed line 114) in the manner of a vortex flow, which directs the flow towards the centre of the entry portion 44 of the inlet chamber 40. The spiralling motion of the gaseous flow tends to cause any oil droplets (as indicated by arrows 116) in the flow to separate from the mainstream flow, being thrown towards the outer surface of the entry portion 44 of the inlet chamber 40, and falling to the floor of the entry portion 44. As mentioned previously, oil droplets collecting on the floor of the entry portion 44 can flow through the first port 97 in the inlet disc 48 into the exit portion 46 and from here can flow through the second port 98 and out through the outlet port 18 of the apparatus 10. The vortex flow 114 benefits the oil separation from the gaseous flow to improve heat transfer efficiency. The in-chamber nozzle 90 is best seen in Figures 4, 5 and 6 and comprises a flared entry channel 94 which provides a communication path between the entry and exit portions 44, 46 of the inlet chamber 40. The flared entry channel 94 defines a relatively wide diameter opening 96 which tapers slightly to a narrower diameter section before opening up into the exit portion 46. The flared nature of the entry channel 94 tends to cause any contaminants (such as oil droplets) which have been separated from the gaseous fuel through the vortex motion to attach to a scooped upper surface 94a of the channel 94, so that the oil droplets are retained within the inlet portion 46, rather than being brought back into the gas flow and flowing into the flared entry channel 94 and onwards to the exit portion 46. Any oil droplets separated from the gaseous flow within the inlet portion therefore tend to fall to the floor of the inlet chamber 40, rather than entering the gas pipes 21. In the floor of the inlet portion 44, oil droplets can pass through a first port 97 in the inlet disc 48 into the exit portion 46 of the inlet chamber. At the base of the exit portion 46 of the inlet chamber 40, the oil droplets can exit the inlet chamber 40 via a second port 98 in the inlet disc 48 and exit the apparatus though the outlet port 18. The arrangement therefore encourages any oil droplets present in the gaseous flow out of the heat exchanger 10, rather than allowing them to enter the gas pipe network 21. This provides an advantage because any oil droplets entering the gas flow pipes 21 otherwise tend to attach to the internal pipe surfaces, which detrimentally effects cooling efficiency. Referring again to Figure 4, in the central portion of the entry portion 44 of the inlet chamber 40, a second contaminant separation feature is provided. The second contaminant separation feature comprises a plug collar 102 mounted towards one end of a plug axle or stem 104 of a plug 100 which extends along the axis A-A of the heat exchanger. The plug 100 is positioned to align, axially, with the entry channel 94. The plug collar 102 is of frusto-conical form and is arranged on the plug axle 104 so that the smaller diameter end of the collar 102 (referred to as the base of the collar) is farthest from the end of the plug which extends into the entry portion 44. In other words, the diameter of the collar tapers to a great diameter end of the collar (referred to as the collar head) closer to the end of the plug 100. A central portion of the plug axle 104 terminates in a relatively pointed tip 106 which extends into the entry portion 44 of the inlet chamber 40. The tip 106 serves to facilitate the clean gas to transit from the spiralling motion within the entry portion 44 to axial motion and helps to direct the gas flow towards the flared entry channel 94. The shape of the flared collar 102 is beneficial as oil droplets which are introduced to the inlet chamber 40 tend to converge around the base of the collar 102 (around the stem 104) and fall under gravity towards the floor of the entry portion 44, rather than being carried forward over the collar surface and towards the pointed tip 106. In other words, the collar 102 carried by the plug 100 serves to encourage any oil droplets within the inlet gaseous to fall away from the onward gaseous flow and reduces the risk of them entering the entry channel 94 in the inlet disc 48. The second head 14, the configuration of the outlet chamber 58 in the second head 14, and the communication path from the gas flow pipes 21, will now be described in further detail with reference to Figure 8, as well as referring back to Figure 1. The outlet chamber 58 comprises an entry portion 120 of relatively wider diameter about the axis A-A and an exit portion 122 of relatively narrower diameter about the axis A-A. An outlet disc 124 (just visible in Figure 8) is arranged within the entry portion 120 of the outlet chamber 58. The outlet disc 124 includes a shaped base 124a and an annular rim 124b which forms an upstand of the disc 124. The base 124a includes a plurality of indents 126 (two of which are identified in Figure 9) which are equi-angularly arranged around the internal circumference of the outlet disc 124, the indents 126 being shaped and sized to cooperate with the gas flow pipes where they communicate with the entry portion 120 of the outlet chamber 58. The outlet disc 124 is typically formed of an elastic material which is able to absorb any deformation of the gas pipes 21 through the effects of heating and / or cooling. The entry portion 120 of the outlet chamber 58 communicates, in a lower region thereof, with the outlet port 19. The outlet disc 124 is also provided with an outlet (not shown but similar to feature 98 for the inlet disc 48) which allows any separated oil from the gaseous flow to pass by the outlet disc 124 and exit through the outlet port 19. Gaseous fuel which flows through the gas pipes 21 of the heat exchanger 10 into the outlet chamber 58 of the second head 14 is cooled by the presence of coolant flowing through the coolant volume 20, before exiting the heat exchanger 10. As seen in Figure 1, the heat exchanger 10 is mounted so that the axis A-A is aligned at an angle to the horizontal. This is not an essential orientation for the heat exchanger 10 but may provide a benefit for some applications. The angle of inclination ensures that any oil within the gaseous flow which may enter the pipes 21, despite the measures taken to avoid this, will pass along the pipes 21 rather than attaching to the internal walls of the pipes 21. Encouraging the oil to flow along the pipes 21 improves the efficiency of the heat exchanger 10 and oil can be conveniently collected via the outlet 19. In practice it may be that the heat exchanger 10 is maintained in horizontal alignment (i.e. is not inclined) and there is only a need for the outlet 18 in the first head 12, or the heat exchanger 10 is inclined and the outlet 19 is provided in the second head 14. It may however be convenient for both the first and second heads 12, 14 to have the outlets 18, 19. In an alternative embodiment as shown in Figure 10, the heat exchanger 210 may include a filter element 130 in the second head 14 to filter any oil droplets which may be entrained within the gaseous flow before the flow exits the heat exchanger 10. The filter 130 is useful if the oil separation measures in the inlet chamber 40 are not quite sufficient, so the filter 130 can capture any remaining oil after the pipes 21. Locating the filter 130 downstream of the coolant volume 20 may be advantageous because here the gas (and any remaining oil) is at lower temperature when filtration performance may be better. If a filter element 130 is used which has adequate performance at higher temperatures, it may be located within the first head 12. The first and second heads 12, 14 may be made from a material which is compatible with hydrogen, but equally the heads may be made from any other material(s) but coated with a hydrogen-barrier material. The gas pipes 21 may be made of welded elements, braised or plastically deformed to provide structural strength and sealing to the first and second supports at each end of the heat exchanger 10. It will be appreciated that preferred and / or optional features of the heat exchanger apparatus are envisaged without departing from the scope of the appended claims.

Claims

1. A heat exchange apparatus (10) for a gaseous fuel flow, the heat exchange apparatus (10) comprising:an inlet chamber (40) defined within a first housing (12) arranged at one end of the heat exchange apparatus (10), the inlet chamber (40) configured to receive a gaseous fuel flow and communicating with a gas flow pipe (21) for receiving the gaseous fuel flow and for delivering the gaseous fuel flow to an outlet chamber (58) defined within a second housing (14), wherein the gas flow pipe (21) extends through a coolant chamber (20) for receiving a coolant which flows around the gas flow pipe (21) to extract heat from the gas flow pipe (21),wherein the inlet chamber (40) is provided with at least one contaminant separation feature (112, 40; 102) to separate contaminants within the gaseous fuel flow from the gaseous fuel to prevent onward passage through the gas flow pipe (21).

2. The heat exchange apparatus (10) as claimed in claim 1, comprising a first contaminant separation feature comprising an inlet nozzle (112) for directing a jet of gaseous fuel flow into the inlet chamber (40) to generate a vortex flow within the inlet chamber (40).

3. The heat exchange apparatus (10) as claimed in claim 2, comprising an insert (48) arranged within the inlet chamber (40) for dividing the inlet chamber (40) into an entry portion (44) and an exit portion (46), wherein the insert (48) is provided with an in-chamber nozzle (90) for allowing gaseous fuel to pass between the entry portion (44) and the exit portion (46).

4. The heat exchange apparatus (10) as claimed in claim 3, wherein the inchamber nozzle (90) comprises a flared entry channel (94).

5. The heat exchange apparatus (10) as claimed in claim 3 or claim 4, wherein the insert comprises a disc (48).

6. The heat exchange apparatus (10) as claimed in claim 5, wherein the insert (48) is provided with an opening to allow contaminants to pass between the entry portion (44) and the exit portion (46) of the inlet chamber (40) in a lower region of the inlet chamber (40).

7. The heat exchange apparatus (10) as claimed in any of claims 3 to 6 when dependent on claim 2, wherein the inlet nozzle (112) is configured to direct the jet of gaseous fuel flow into the entry portion (44) of the inlet chamber (40).

8. The heat exchange apparatus (10) as claimed in any of claims 1 to 7, comprising a second contaminant separation feature comprising a flared collar (102) which projects into the inlet chamber (40).

9. The heat exchange apparatus (10) as claimed in claim 8, wherein the flared collar (102) is carried by a plug (100) carried by the first housing (12).

10. The heat exchanger apparatus (10) as claimed in claim 8 or claim 9, wherein the flared collar flares outwardly into the inlet chamber (40) from a relatively smaller diameter region to a relatively larger diameter region of the collar, wherein the relatively larger diameter region projects further into the inlet chamber (40).

11. The heat exchange apparatus (10) as claimed in any of claims 1 to 10, comprising an outlet port (18) which communicates with the inlet chamber (40) through a floor of the inlet chamber (40) to allow exit of separated contaminants from the gaseous fuel flow.

12. The heat exchange apparatus (10) as claimed in any of claims 1 to 11, comprising a plurality of gas flow pipes (21) supported by a plurality of baffles (60A, 70A, 80A) arranged within the coolant chamber (20).

13. The heat exchange apparatus (10) as claimed in any of claims 1 to 12, wherein the inlet chamber (40) comprises an outlet port (18) provided in a floor of the inlet chamber (40) to allow exit of separated contaminants from the gaseous fuel flow.

14. The heat exchange apparatus (10) as claimed in any of claims 1 to 13, comprising a first seal (36) between the inlet chamber (40) and the coolant chamber (20) to prevent mixing of gaseous fuel and coolant and / or a second seal (34) between the coolant chamber (20) and the outlet chamber5 (58) to prevent mixing of gaseous fuel and coolant.

15. The heat exchange apparatus (10) as claimed in any of claims 1 to 14, comprising a filter (130) arranged within the outlet chamber (58) for capturing contaminants remaining within the gaseous flow before exiting 10 the heat exchange apparatus (10).

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