GB2461854A

GB2461854A - Heat exchange unit for cooling engine exhaust emissions

Info

Publication number: GB2461854A
Application number: GB0812696A
Authority: GB
Inventors: Stephen John Heard
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-07-11
Filing date: 2008-07-11
Publication date: 2010-01-20
Also published as: GB0812696D0

Abstract

A heat exchange unit for cooling the exhaust emissions produced by the internal combustion engine of an agricultural vehicle, such as a tractor. The heat exchange unit includes an inlet for receiving the exhaust emissions produced by the internal combustion engine and an outlet for the cooled exhaust emissions. The heat exchange unit also includes mounting means, as mounting brackets, to enable it to be mounted to an agricultural vehicle. The heat exchange unit may be mounted at a front region, or more preferably a lower front region, of the agricultural vehicle. In a further aspect, an agricultural assembly comprising an agricultural vehicle and a heat exchange unit is disclosed. Preferably, the agricultural assembly comprises an agricultural implement, such as a seeder apparatus or tillage equipment, which is connected to the outlet of the heat exchange unit by a conduit and includes means for incorporating cooled exhaust emissions into a soil to improve soil fertility.

Description

TITLE

Apparatus for recycling exhaust emissions

DESCRIPTION

Technical Field

The present invention relates to apparatus for recycling exhaust emissions (exhaust gases) such as those emitted by an agricultural vehicle (e.g. a tractor), and in particular to a heat-exchange unit that is used to cool the exhaust emissions before they are incorporated into agricultural soils to improve the fertility of the soil and to promote bioactivity and crop growth.

Background Art

It is known to incorporate the exhaust emissions of agricultural vehicles into agricultural soils (e.g. soils that are used for the production of food and fibre crops) using an apparatus where the exhaust emissions from the internal combustion engine of the agricultural vehicle are directed into a heat-exchange unit using suitable piping.

The exhaust emissions are cooled by the heat-exchange unit and then incorporated into the soil structure using a suitably modified agricultural implement such as a * : *: :* 20 seeder apparatus or tillage equipment, for example.

* ** * All previous practical implementations of such apparatus have required the use of a : physically large heat-exchange unit (often incorporating very long straight heat- * exchange pipes through which the exhaust emissions are passed) that is mounted on a I. S towed trailer behind the agricultural vehicle. In other words, the agricultural vehicle * . . 25 tows a trailer carrying the heat-exchange unit which is then used to tow an agricultural * : * * implement. The overall length of such a towed assembly means that it is completely unsuitable for use in small fields such as those found in the United Kingdom and continental Europe. As a result, there is a need for an improved heat-exchange unit that is physically small enough to be mounted directly to the agricultural vehicle itself. This will also remove the need for extensive flexible tubing and piping between the agricultural vehicle and the towed trailer carrying the heat-exchange unit and allows a more robust, rigid connection to be made between the exhaust outlet of the agricultural vehicle and the heat-exchange unit.

Summary of the Invention

The present invention provides an improved heat-exchange unit for cooling the exhaust emissions produced by the internal combustion engine of an agricultural vehicle (e.g. a tractor), the heat-exchange unit including an inlet for receiving the exhaust emissions produced by the internal combustion engine and an outlet for the cooled exhaust emissions, wherein the heat-exchange unit includes mounting means to enable it to be mounted to the agricultural vehicle.

The heat-exchange unit preferably includes an exhaust emissions conduit that extends between the inlet and the outlet. A plurality of cooling tubes are arranged within the exhaust emissions conduit and are adapted to receive a cooling fluid. The exhaust emissions will normally be supplied to the inlet of the heat-exchange unit directly from the exhaust outlet of the agricultural vehicle and will therefore be at an elevated temperature of about 500 °C. However, the composition of the exhaust emissions obtained from the exhaust outlet of the agricultural vehicle may optionally be altered or conditioned in a working chamber to suit any particular soil type or crop type * :* *. 20 before being supplied to the inlet of the heat-exchange unit. S.. S * S *..

:. The exhaust emissions may also be mixed with a small quantity of suitable gas (e.g. * ambient or cooled air, or the cooled exhaust emissions) to reduce the temperature of *5* the exhaust emissions before they are supplied to the inlet of the heat-exchange unit.

* . . 25 For example, a small quantity of the cooled exhaust emissions might be drawn out of * . the heat-exchange unit or any suitable conduit means connected to the outlet and then directed back to suitable conduit means connected between the exhaust outlet of the agricultural vehicle and the inlet of the heat-exchange unit.

As the exhaust emissions pass through the exhaust emissions conduit they will be cooled by transferring heat to the cooling fluid flowing through the cooling tubes. It is preferred that the exhaust emissions leaving the heat-exchange unit through the outlet are at a temperature of about 65 °C.

The plurality of cooling tubes may extend between a pair of opposite surfaces of an inner housing that contains the exhaust emissions conduit. The open ends of the cooling tubes are preferably aligned with corresponding openings provided in the pair of opposite surface of the inner housing and sealed to the respective opposite surfaces to prevent the cooling fluid from entering the exhaust emissions conduit. The size and shape of the cooling tubes and the exhaust emissions conduit, the array or pattern in which the cooling tubes are arranged within the exhaust emissions conduit, and the particular arrangement and location of any baffles or internal walls within the exhaust emissions conduit (see below) can also be selected to promote cooling of the exhaust emissions.

The inner housing may contain a plurality of parallel exhaust emission conduits. In this case, each exhaust emission conduit will preferably extend between a common inlet for receiving the exhaust emissions produced by the internal combustion engine and a respective outlet for the cooled exhaust emissions. Any suitable number of * parallel exhaust emissions conduits may be provided. The respective outlets may be ... 20 connected together to form a common outlet for the cooled exhaust emissions. ****

*.**. Dividing the exhaust emissions between parallel exhaust emissions conduits promotes cooling and results in a heat-exchange unit having smaller physical dimensions. ***

The heat-exchange unit preferably includes an outer housing or shroud arranged * . . 25 outside the inner housing. The outer housing preferably includes a cover surface and * : ** side walls. The heat-exchange unit will normally be mounted to the agricultural vehicle in such a way that the cover surface of the outer housing forms an upper surface of the heat-exchange unit. The inner and outer housing parts can be secured together using any supporting frame or structure. Such a supporting frame or stiucture may also incorporate means for mounting the heat-exchange unit to the agricultural vehicle in the form of mounting brackets, for example.

The cover surface of the outer housing is preferably spaced apart from one of the pair of opposite surfaces (e.g. the upper surface) of the inner housing to define a manifold chamber for the cooling fluid. One or more of the side walls of the outer housing are preferably spaced apart from the inner housing to define one or more cooling passages between the inner housing and the outer housing. The open ends of the cooling tubes sealed to the one of the pair of opposite surfaces are therefore in fluid communication with the manifold chamber and cooling fluid supplied to the manifold chamber will flow through the cooling tubes. The cooling fluid will also flow through the cooling passages provided between the inner housing and the outer housing. Heat may therefore be transferred through the side wall(s) of the inner housing to the cooling fluid flowing through the one or more cooling passages.

The heat-exchange unit preferably further includes means for introducing cooling fluid into the manifold chamber. For example, an electric fan may be used to draw ambient air from around the heat-exchange unit through the cover surface of the outer housing and into the manifold chamber. The electric fan may be mounted in a corresponding opening provided in the cover surface of the outer housing or in a duct part of the cover surface, for example. The outer housing can be completely open on its underside to provide a large vent through which the heated air can exit the heat- * : ::* 20 exchange unit after passing through the cooling tubes. S... * S S...

It is generally preferred that the heat-exchange unit uses ambient air as the cooling : fluid because it is readily available and the heated air can simply be discharged to the environment. It may sometimes be desirable to cool the ambient air before it is 25 passed through the cooling tubes. This can be achieved by any suitable cooling * :.: method or apparatus. The heat-exchange unit may use other cooling fluids (e.g. water or a suitable refrigerant gas or liquid) in a closed-loop cooling circuit that may optionally include a compressor, a condenser and an evaporator, for example.

The engine compartment housing the internal combustion engine is normally located at a front upper part of the agricultural vehicle. A number of individual cooling systems are normally located in the engine compartment for cooling the engine, fuel, transmission oil, cabin air conditioning etc. The heat produced by these cooling systems and the normal operation of the internal engine is normally removed by a fan which draws ambient air into the engine compartment through an air intake and then ejects the heated air from the engine compartment. This means that the temperature of the air in the region of the engine compartment (or in the region behind the engine compartment assuming that the agricultural vehicle is being driven forwards) will be considerably higher than the temperature of the ambient air that is remote from the engine compartment. Mounting the heat-exchange unit at a front region of the agricultural vehicle (and most preferably at a lower front region) means that the ambient air used by the heat-exchange unit will be as cold as possible since it will not have undergone any mixing with the heated air ejected from the engine compartment.

The heated air that has passed through the cooling tubes of the heat-exchange unit can also be safely ejected down towards the ground underneath the agricultural vehicle. It will be readily appreciated that care must be taken with the ejection of the heated air because it may exit the heat-exchange unit at temperatures of about 200 °C.

The inner housing may include an intermediate surface between the pair of opposite surfaces that divides the or each exhaust emissions conduit into a first conduit part on one side of the intermediate surface and a second conduit part an the other side of the * 20 intermediate surface. It will be readily appreciated that additional intermediate ***. surfaces can be provided with n surfaces dividing the or each exhaust emissions :. conduit into n+ 1 conduit parts. The or each intermediate surface will include an * : opening or aperture to allow the exhaust emissions to flow between adjacent conduit S..

parts. : 25

* : * Each conduit part of the exhaust emissions conduit may provide different amounts of cooling. For example, if the heat-exchange unit is mounted to the agricultural vehicle such that the cooling tubes are substantially vertical and the cooling fluid flows in a downward direction then an upper conduit part may provide more cooling than a lower conduit part since the temperature of the cooling fluid will increase as it flows down through the cooling tubes. An increase in temperature means that the cooling fluid has less ability to cool the exhaust emissions flowing through the exhaust emissions conduit. The heat-exchange unit may therefore be adapted to try and maximise cooling of the exhaust emissions in an upper conduit part, for example by making the exhaust emissions follow a more tortuous flow path through the upper conduit part. It may be preferred that the exhaust emissions will flow first through the conduit part that provides the least amount of cooling (e.g. the inlet may be located in the lowest conduit part of the heat-exchange unit) so that the amount of cooling provided by the cooling fluid effectively increases as the temperature of the exhaust emissions decreases as they flow through the exhaust emissions conduit.

The plurality of cooling tubes will normally pass through corresponding openings in the or each intermediate surface. The cooling tubes are preferably sealed to the or each intermediate surface to prevent the cooling fluid from entering the exhaust emissions conduit.

The exhaust emissions may be introduced into the first conduit part of the or each exhaust emissions conduit through the inlet. In other words, when the heat-exchange unit is mounted to the agricultural vehicle, the exhaust emissions will preferably flow through the first conduit part, upwards through the opening or aperture in the intermediate surface, and then through the second conduit part that is arranged above the intermediate surface before leaving the heat-exchange unit through the outlet. S...

The inner housing preferably includes baffles or internal walls to direct the passage of * the exhaust emissions through the or each exhaust emissions conduit. The * *;: arrangement of baffles or internal walls may be different in the various conduit parts of the or each exhaust emissions conduit. For example, the baffles or internal walls :0.*: 25 may be arranged such that the exhaust emissions must follow a more tortuous flow * : * s path in the second conduit part than in the first conduit part or vice versa.

The present invention further provides an apparatus for recycling exhaust emissions produced by the internal combustion engine of an agricultural vehicle, the apparatus comprising a heat-exchange unit as described above, and means for incorporating the cooled exhaust emissions into a soil structure.

The apparatus preferably further includes conduit means for supplying the exhaust emissions to the inlet of the heat-exchange unit.

The apparatus preferably further includes conduit means for supplying the cooled exhaust emissions from the outlet of the heat-exchange unit to the means for incorporating the cooled exhaust emissions into the soil structure.

The means for incorporating the cooled exhaust emissions into the soil structure may be an agricultural implement such as a seeder apparatus or tilage equipment, for example. The agricultural implement may be specifically designed to be used with the apparatus for recycling exhaust emissions or may be adapted or modified retrospectively to enable the cooled exhaust emissions to be delivered below the surface of the soil, typically through one or more ground working elements of the agricultural implement.

The present invention further provides an agricultural vehicle (e.g. a tractor) having an internal combustion engine producing exhaust emissions and a heat-exchange unit as described above for cooling the exhaust emissions mounted to the agricultural vehicle. The heat-exchange unit is preferably mounted at a front region of the * : :* 20 agriculal vehicle, and most preferably at a lower front region, for the reasons given **** * * above. ** * *

* Suitable conduit means (e.g. tubing or piping) will preferably be used to connect the inlet of the heat-exchange unit to an exhaust outlet of the internal combustion engine * . . 25 of the agricultural vehicle. The inlet of the heat-exchange unit may also be connected * : **.: to a working chamber where the composition of the exhaust emissions obtained from the exhaust outlet of the agricultural vehicle may optionally be altered or conditioned to suit any particular soil type or crop type. The exhaust emissions may also be mixed with a small quantity of suitable gas (e.g. ambient or cooled air) to reduce the temperature of the exhaust emissions before they are supplied to the inlet of the heat-exchange unit.

The cooled exhaust emissions can be incorporated into the soil structure using any suitable means that delivers the exhaust emissions below the surface of the soil. For example, if the agricultural vehicle is a tractor then a towed agricultural implement may be used to incorporate the cooled exhaust emissions.

An agricultural vehicle may also include means to incorporate the cooled exhaust emissions into the soil structure. This may be particularly useful for agricultural vehicles such as combine harvesters or crop spraying vehicles which might not be used to tow an agricultural implement having ground working elements.

The present invention further provides an agricultural assembly comprising an agricultural vehicle (e.g. a tractor) having an internal combustion engine producing exhaust emissions, and a heat-exchange unit for cooling the exhaust emissions, the heat-exchange unit including an inlet for receiving the exhaust emissions, an outlet for the cooled exhaust emissions, and mounting means to enable it to be mounted to the agricultural vehicle. The heat-exchange unit is preferably mounted at a front region of the agricultural vehicle, and most preferably at a lower front region, for the reasons given above.

*:*::* 20 Suitable conduit means (e.g. tubing or piping) will preferably be used to connect the * **.

1**** inlet of the heat-exchange unit to an exhaust outlet of the internal combustion engine of the agricultural vehicle. The inlet of the heat-exchange unit may also be connected * .;: to a working chamber where the composition of the exhaust emissions obtained from the exhaust outlet of the agricultural vehicle may optionally be altered or conditioned * 25 to suit any particular soil type or crop type. The exhaust emissions may also be mixed * * with a small quantity of suitable gas (e.g. ambient or cooled air) to reduce the temperature of the exhaust emissions before they are supplied to the inlet of the heat-exchange unit.

The agricultural assembly preferably includes an agricultural implement connected to the agricultural vehicle having means for incorporating the cooled exhaust emissions into the soil. Suitable conduit means (e.g. tubing or piping) will preferably be used to connect the outlet of the heat-exchange unit with a part of the agricultural implement.

The agricultural implement may be a seeder apparatus or tillage equipment, for example. The agricultural implement may be specifically designed to be used with the apparatus for recycling exhaust emissions or may be adapted or modified retrospectively to enable the cooled exhaust emissions to be delivered below the surface of the soil, typically through one or more ground working elements of the agricultural implement. For example, in the case of a conventional air seeder the cooled exhaust emissions can be mixed with the pressurised air into which the seed is entrained and then directed into the individual furrows created by the ground working elements. The temperature at which the cooled exhaust emissions are supplied to the air seeder must be sufficiently low to avoid causing damage to the pressurised air system. In the case of tillage equipment, the cooled exhaust emissions can be directed along modified ground working elements or along suitable tubing or piping that is secured to the ground working elements such that the cooled exhaust emissions are delivered under the surface of the soil.

* Exhaust emissions from agricultural vehicles (e.g. tractors) are known to contain compounds such as hydrocarbons, carbon monoxide (CO), carbon dioxide (C02), S...

nitrogen oxides (NOr) and sulphur oxides (SO), which when incorporated into the soil structure may help to improve soil fertility and promote bioactivity and crop growth. The composition of the exhaust emissions may optionally be determined by adding an appropriate agent or additive to the fuel of the agricultural vehicle or by :: 25 controlling the combustion of the fuel by the internal combustion engine.

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Recycling the exhaust emissions reduces the amount of harmfli.l emissions and pollutants that are emitted into the atmosphere by the agricultural vehicle during its normal operation and can reduce the amount of chemical fertilisers that need to be applied to the soil. It will therefore be readily apparent that recycling exhaust emissions has considerable environmental benefits in addition to the cost savings that arise from the reduction in the amount of chemical fertilisers needed.

Drawings Figure 1 is a top view of a heat-exchange unit according to the present invention; Figure 2 is a rear view of the heat-exchange unit of Figure 1 showing two cooling pipes is cut away; Figure 3 is a cross section view along the line 3-3 of Figure 2 without the outer housing; Figure 4 is a cross section view along the line 4-4 of Figure 2 without the outer housing; and Figure 5 is a side view showing the heat-exchange unit of Figure 1 mounted to a tractor.

It will be readily appreciated that all references below to "upper" and "lower" refer to the orientation of the heat-exchange unit when it is mounted to a tractor.

A generally U-shaped heat-exchange unit 1 includes an outer housing or shroud 2 made of sheet steel having an upper surface 2a and side walls 2b to 2j that define a downwardly extending shirt portion. The outer housing 2 is completely open on its underside. * *5 * . S ** 20 * bSS

* ** Six electric fans 4 are mounted in corresponding openings provided in the upper surface 2a of the outer housing. Since agricultural vehicles such as tractors tend to * .:. move forward at relatively low speed, there is little opportunity for ambient air flowing past the heat-exchange unit 1 to be directed inside the outer housing 2 via air * * 25 inlets or the like. However, the outer housing 2 may optionally include suitably * : shaped air inlets to supplement the ambient air that is drawn into the outer housing by the electric fans 4 if they are considered to be practical. The electric fans 4 may also be mounted in suitably shaped ducts.

An inner housing 6 is shown ghosted in Figures 1 and 2 and is located generally within the outer housing 2. The inner housing 6 includes an upper surface 6a, side walls 6b to 6j and a lower surface 6k and encloses an exhaust emissions conduit for cooling the exhaust emissions. As shown in Figure 2, the inner housing 6 is divided into two levels or conduit parts by an intermediate surface 8. A lower level (first conduit part) 10 includes an inlet 12 for receiving exhaust emissions and an upper level (second conduit part) 14 includes a pair of outlets 1 6a and 1 6b through which the cooled exhaust emissions exit the inner housing 6.

The inlet 12 and outlets 14a and 14b extend through corresponding openings or slots provided in the side walls 2i and 2e of the outer housing 2.

A plurality of cooling tubes 18 extend vertically between the upper surface 6a and the lower surface 6k. The upper and lower surfaces 6a and 6k include a corresponding plurality of openings such that the open ends of the cooling tubes 18 are aligned with the openings. The cooling tubes 18 also pass through corresponding openings in the intermediate surface 8. The cooling tubes 18 are fixed (e.g. welded) to the horizontal surfaces of the inner housing 6 in an air-tight manner such that there is no prospect of the cooling air leaking into the exhaust emissions conduit. Two vertical cooling tubes 18 are shown in Figure 2 through the cut-away region by way of example.

The outer dimensions of the inner housing 6 are smaller than the corresponding inner dimensions of the outer housing 2. The respective upper surfaces 2a and 6a of the outer and inner housings are spaced apart from each other to define a manifold * chamber 20. Similarly, the respective side walls 2b-2j and 6b-6j of the outer and * .:. inner housings are spaced apart from each other to defme vertical cooling passages 22. Structural elements (not shown) are used to secure the inner housing 6 within the : 25 outer housing 2 with this particular spacing.

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During operation of the heat-exchange unit, ambient air is drawn through the upper surface 2a of the outer housing by the operation of the fans 4 as shown by the block arrows in Figure 2. Air is therefore supplied to the manifold chamber 20 between the respective upper surfaces 2a and 6a of the outer and inner housing. The air flows from the manifold chamber 20 through the plurality of cooling tubes 18 where heat is transferred from the exhaust emissions to the cooling air through the cylindrical walls -12 -of the cooling tubes. The air also flows from the manifold chamber 20 through the vertical cooling passages 22 (i.e. around the outside of the inner housing 6) where heat is transferred from the exhaust emissions to the cooling air through the side walls of the inner housing. The heated air is then ejected into the atmosphere through the open underside of the outer housing 2 as shown by the block arrows in Figure 2.

The upper and lower levels 10 and 14 of the inner housing 6 will now be described in more detail with reference to Figures 3 and 4. The pattern or array of cooling tubes 18 within the inner housing 6 is clearly shown and can be selected to provide optimum cooling. Similarly, the diameter of the cooling tubes can be selected with reference to the required cooling and the amount of cooling air that is to be drawn into the manifold chamber 20 by the fans 4.

Each of the upper and lower levels is divided into two distinct flow paths for the exhaust emissions and these are represented by the block arrows. On entiy to the lower level 10 through the inlet 12 the exhaust. emissions are divided by a divider baffle 24 into the two distinct flow paths. The flow of exhaust emissions is directed through the lower level 10 by a U-shaped baffle 26 such that the exhaust emissions flow around the opposite arms of the U-shaped baffle until they reach a forward extension of the divider baffle 24. The exhaust emissions then flow upwardly through openings 28 in the intermediate surface 8 of the inner housing 6 and into the upper :. level 14. The exhaust emissions remain divided in the upper level 14 by a divider :. baffle 30 and are directed through the upper level by a complex arrangement of baffles 32 until they reach the respective outlets 16a and l6b. As the exhaust : 25 emissions impinge on the cooling tubes 18 and the side walls of the inner housing * : (and also in the case of the upper level 14, the upper surface 6a of the inner housing), the exhaust emissions will be cooled by transferring heat into the cooling air flowing through the cooling tubes and the vertical cooling passages 22.

It will be readily appreciated that the flow path of the exhaust emissions through the upper level 14 is considerably more tortuous than the flow path in the lower level 10.

It is therefore expected that the exhaust emissions will experience a greater -13 -temperature drop in the upper level 14 than in the lower level 10. This is because the temperature of the cooling air will increase as it flows down through the cooling tubes 18. The amount of cooling will therefore be greater in the upper level 14 where the cooling air is colder and this is then maximised by providing the upper level 14 with a more tortuous flow path.

Figure 5 shows the heat-exchange unit 1 mounted at a lower front region of a tractor by means of mounting brackets (not shown). The arms of the generally U-shaped heat-exchange unit 1 are received on opposite sides of the front region of the tractor 100 such that there is sufficient space to allow for connections to be made to the inlet 12 and the outlets 16a and 16b --only outlet 16a is shown in Figure 5 since the other outlet 1 6b is located on the other side of the tractor.

The inlet 12 is connected to an exhaust outlet of the internal combustion engine (not shown) of the tractor by suitable piping (not shown) that is fixed to the tractor. The outlets 16a and 16b are joined together to form a common outlet (not shown) that is connected to a suitably modified agricultural implement (e.g. a seeder apparatus or * ** tillage equipment) which is not shown but which would be towed by the tractor 100.

The common outlet is connected to the agricultural implement by suitable piping (not shown). The heat-exchange unit, agricultural implement and the various connecting piping together form an apparatus for recycling the exhaust emissions produced by the internal combustion engine of the tractor 100.

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* When the apparatus for recycling the exhaust emissions is in use, ambient air from the * : *: 25 vicinity of the front of the tractor 100 is drawn into the heat-exchange unit 1 by the fans 4 and the hot air is discharged underneath the tractor as shown.

Drawing in ambient air from the vicinity of the front of the tractor 100 is preferable because such air will not have undergone any mixing with the heated air ejected from the engine compartment. The heated air from the heat-exchange unit can also be safely ejected down towards the ground underneath the agricultural vehicle.

-14 -Hot exhaust emissions are supplied to the inlet of the heat-exchange where they are cooled to about 65 °C before being directed to the agricultural implement to be incorporated into the soil structure. * .0 * * S * .* * S.. * . S... 0* * S * *.S **.

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Claims

-15 -CLAIMS1. A heat-exchange unit for cooling the exhaust emissions produced by the internal combustion engine of an agricultural vehicle, the heat-exchange unit including an inlet for receiving the exhaust emissions produced by the internal combustion engine and an outlet for the cooled exhaust emissions, wherein the heat-exchange unit includes mounting means to enable it to be mounted to the agricultural vehicle.
2. A heat-exchange unit according to claim I, further comprising an exhaust emissions conduit extending between the inlet and the outlet for the passage of exhaust emissions through the heat-exchange unit, and a plurality of cooling tubes arranged within the exhaust emissions conduit along which a cooling fluid is passed to cool the exhaust emissions.
3. A heat-exchange unit according to claim 2, wherein the plurality of cooling tubes extend between a pair of opposite surfaces of an inner housing that defines the exhaust emissions conduit. * .. * S I
4. A heat-exchange unit according to claim 2 or claim 3, wherein the plurality of cooling tubes are arranged in a pattern within the exhaust emissions conduit so as to promote cooling of the exhaust emissions. * *.* *
5. A heat-exchange unit according to any of claims 2 to 4, wherein the inner ** S...* : housing defmes a plurality of parallel exhaust emission conduits, each exhaust S.....* * 25 emission conduit extending between a common inlet for receiving the exhaust emissions produced by the internal combustion engine and a respective outlet for the cooled exhaust emissions.
6. A heat-exchange unit according to any of claims 3 to 5, further comprising an outer housing arranged outside the inner housing that includes a cover surface and side walls.
7. A heat-exchange unit according to claim 6, wherein the cover surface of the outer housing is spaced apart from one of the pair of opposite surfaces of the inner housing to defme a manifold chamber for the cooling fluid.
8. A heat-exchange unit according to claim 7, wherein one or more of the side walls are spaced apart from the inner housing to define one or more cooling passages between the inner housing and the outer housing.
9. A heat-exchange unit according to claim 7 or claim 8, further comprising means for introducing cooling fluid into the manifold chamber.
10. A heat-exchange unit according to any of claims 7 to 9, further comprising a device for drawing cooling fluid through the cover surface of the outer housing and into the manifold chamber.
11. A heat-exchange unit according to claim 10, wherein the device is an electric fan and the cooling fluid is ambient air drawn from around the heat-exchange unit. * **::::::
12. A heat-exchange unit according to claim 11 wherein the electric fan is mounted in the cover surface of the outer housing. ** * S * ***:. 14. A heat-exchange unit according to any of claims 3 to 13, wherein the inner housing includes an intermediate surface between the pair of opposite surfaces that *.**.* * divides the or each exhaust emissions conduit into a first conduit part on one side of * : 25 the intermediate surface and a second conduit part on the other side of the intermediate surface.15. A heat-exchange unit according to claim 14, wherein the plurality of cooling tubes pass through corresponding openings in the intermediate surface.-17 - 16. A heat-exchange unit according to claim 14 or claim 15, wherein the exhaust emissions are introduced into the first conduit part of the or each exhaust emissions conduit through the inlet.17. A heat-exchange unit according to any of claims 14 to 16, wherein the first and second conduit parts provide different amounts of cooling.18. A heat-exchange unit according to any of claims 3 to 17, wherein the inner housing includes baffles or internal walls to direct the passage of the exhaust emissions through the or each exhaust emissions conduit.19. A heat-exchange unit according to any preceding claim, wherein the heat-exchange unit includes mounting means to enable it to be mounted at a front region of the agricultural vehicle.20. A heat-exchange unit according to any preceding claim, wherein the heat-exchange unit includes mounting means to enable it to be mounted at a lower front region of the agricultural vehicle. * .**21. An apparatus for recycling exhaust emissions produced by the internal combustion engine of an agricultural vehicle, the apparatus comprising a heat- *, exchange unit according to any preceding claim, and means for incorporating the cooled exhaust emissions into a soil structure.* *.** * . * * 25 22. An apparatus according to claim 21, further comprising conduit means for supplying the exhaust emissions to the inlet of the heat-exchange unit.23. An apparatus according to claim 21 or claim 22, further comprising conduit means for supplying the cooled exhaust emissions from the outlet of the heat-exchange unit to the means for incorporating the cooled exhaust emissions into the soil structure.-18 - 24. An apparatus according to any of claims 21 to 23, wherein the means for incorporating the cooled exhaust emissions into the soil structure is a seeder apparatus.25. An apparatus according to any of claims 21 to 23, wherein the means for incorporating the cooled exhaust emissions into the soil structure is tillage equipment.26. An agricultural vehicle having an internal combustion engine producing exhaust emissions and a heat-exchange unit according to any of claims I to 20 for cooling the exhaust emissions mounted to the agricultural vehicle.27. An agricultural vehicle according to claim 26, wherein the heat-exchange unit is mounted at a front region of the agricultural vehicle.28. An agricultural vehicle according to claim 26 or claim 27, wherein the heat-exchange unit is mounted at a lower front region of the agricultural vehicle.* .. 29. An agricultural vehicle according to any of claims 26 to 28, further comprising conduit means for connecting the inlet of the heat-exchange unit to an exhaust outlet of the internal combustion engine. S. * . * ..*30. An agricultural assembly comprising: an agricultural vehicle having an internal combustion engine producing S. S**S * : exhaust emissions; and * * 25 a heat-exchange unit mounted to the agricultural vehicle for cooling the exhaust emissions, the heat-exchange unit including an inlet for receiving the exhaust emissions, and an outlet for the cooled exhaust emissions.31. An agricultural assembly according to claim 30, further comprising conduit means for connecting the inlet of the heat-exchange unit to an exhaust outlet of the internal combustion engine of the agricultural vehicle.32. An agricultural assembly according to claim 30 or claim 31, further comprising an agricultural implement connected to the agricultural vehicle having means for incorporating the cooled exhaust emissions into a soil.33. An agricultural assembly according to claim 32, further comprising conduit means for connecting the outlet of the heat-exchange unit with a part of the agricultural implement.34. An agricultural assembly according to claim 32 or claim 33, wherein the agricultural implement is a seeder apparatus.35. An agricultural assembly according to claim 32 or claim 33, wherein the agricultural implement is tillage equipment.36. An agricultural assembly according to any of claims 30 to 35, wherein the agricultural vehicle is a tractor.37. An agricultural assembly according to any of claims 30 to 36, wherein the heat-exchange unit is mounted at a front region of the agricultural vehicle. *...38. An agricultural assembly according to any of claims 30 to 37, wherein the * heat-exchange unit is mounted at a lower front region of the agricultural vehicle.S. .**.* 39. A heat-exchange unit substantially as herein described and with reference to *..S** * 25 the drawings.