WO2006120709A1

WO2006120709A1 - Multistage condensation reactor within sonic cavity

Info

Publication number: WO2006120709A1
Application number: PCT/IT2006/000315
Authority: WO
Inventors: Luciano Alunni
Original assignee: Luciano Alunni
Priority date: 2005-05-06
Filing date: 2006-05-04
Publication date: 2006-11-16
Also published as: ITRM20050219A1

Abstract

This invention concerns a multistage condensation reactor within sonic cavity for treating exhaust gas of internal combustion engines, characterised in that it includes a body with couplings to the gas exhaust duct on one extremity and a jet head (13) or outlet on the other extremity. Said body is hollow internally so as to create a line for conveying the gas from the couplings to the exhaust duct to said outlet head (13) . The layout internal to said body is constituted, from the coupling end with said container toward said jet head (13) , of a first converging zone AB, a diverging zone BC and CD and by a second converging zone DE, in proximity to said jet head (13) , internally to said passage in the body, since it includes an internal flow diffuser (7) , and all in such a manner as to condensate said exhaust gas at the outlet from said jet head (13) .

Description

MULTISTAGE CONDENSATION REACTOR WITHIN SONIC CAVITY

This invention refers to a multistage condensation reactor within sonic cavity. In greater detail, the invention concerns a reactor for the final treatment of propulsor exhaust gas for internal combustion engines.

According to a definition provided by the "Marine Pollution Scientific Group", pollution is the "introduction into the environment of substances or energy capable of creating a risk to human health, danger for living beings or ecosystems, damage to structures or to the countryside, or that may interfere with the legitimate uses of said environment" . Pollution occurs when the environment's ability to purify itself is strained because the quantities of the substances introduced into the environment are greater than those that the reactions of photolysis and hydrolysis and the metabolic activities of organisms capable of degrading can deal with.

It is known that vehicular traffic is one of the most significant components of air pollution in urban areas and, therefore, permanent measures must be adopted that limit the exhaust gas generated by automobiles .

It is also known that automobiles are equipped with an alternating engine propulsor and are powered with petrol or diesel fuel. In the combustion engine, if petrol combustion takes place under ideal conditions, it would form only water (H₂O) and carbon dioxide (CO₂) according to the following relationship: HC + O₂ + spark = H₂O + CO₂ + heat. Unfortunately, however, the actual combustion that takes place in engine cylinders is quite different and generates numerous polluting molecules. Two types of problems arise :

1) - combustion occurs by means of an explosion and thus is too rapid and cannot be completed. Along with H₂O and CO₂, exhaust gas also contains the products of incomplete combustion: carbon monoxide (CO) and hydrocarbons (HC) that have not been completely burned. Some molecular O₂ that has not reacted also remains;

2) - oxygen in the air, in addition to burning petrol, can also burn nitrogen N₂, thus forming nitric oxides NO and NO₂ that are collectively indicated as NO_x. This occurs to an even greater extent in Diesel engines, where there are much higher pressure and temperature values .

Thus, real combustion in an internal combustion engine, in addition to generating H₂O and CO₂, also produces both over and under oxidized molecules, nitric oxides NO_x, carbon monoxide and unburned hydrocarbons. This situation can be represented with the formula: HC + O₂ + N₂ + spark = H₂O + CO₂ + NO_x + CO + HC + heat.

These are extremely polluting substances and, to eliminate them, a catalytic muffler was introduced. This is a small chemical reactor built into the car's exhaust system, and located between the engine and the traditional (two-stage) muffler or silencer.

The catalytic muffler can be built entirely out of metal or may also include some ceramic parts, depending on the manufacturer. Generally, it consists of a honeycomb structure, covered with a thin film of catalyzing metals, such as Palladium (Pd) , Rhodium (Rh) and Platinum (Pt) . When the exhaust gas flows through the catalytic converter, said metals facilitate the chemical reactions that convert the polluting substances, i.e. nitric oxides (NO_x) , carbon monoxide (CO) , and unburned hydrocarbons (HC) , into harmless compounds, such as nitrogen (N₂) , carbon dioxide (CO₂) and water (H₂O) .

The catalytic (reducing and oxidizing) muffler is a rather delicate chemical reactor that cannot withstand large changes in temperature or the presence of some substances, such as lead (Pb) and sulphur (S) .

Furthermore, to function efficiently, its operating temperature must range between 300⁰C and 900⁰C while the composition of the exhaust gas produced by the combustion in the engine must be constant. For this reason, an efficient muffler (trivalent, i.e. capable of trapping all three main pollutants NO_x, CO and HC) requires an electronic control unit (electronic injection) to regulate the quantity of air and fuel injected into the cylinders based on a feedback signal generated by a sensor (lambda probe) installed on the inlet line to the catalytic converter.

A series of reduction and oxidisation reactions takes place in a trivalent catalytic muffler that, today, is installed on all petrol-powered automobiles. If the exhaust gas contains an inadequate amount of oxygen (rich carburetion) , there will be an excessive amount of CO and HC that, subtracting the oxygen from the nitric oxides, will produce more carbon dioxide and water, releasing nitrogen N₂ according to the following reduction relationship: NO_x + CO + HC (Rh) N₂ + H₂O+CO₂.

On the contrary, if oxygen is available (lean carburetion) , carbon monoxide and unburned hydrocarbons will absorb it, forming water and carbon dioxide, in a kind of post-combustion reaction, called "oxidation reaction", i.e. CO + HC + O₂ (Pi) H₂O + CO₂.

It appears evident that, to create the reduction reaction, and thus remove the oxygen from the NO_x, converting it into N₂, there must be carbon monoxide and hydrocarbons, something that occurs with rich carburetion. But, in this manner, the excess CO and the HC would be emitted into the environment . On the other hand, to create the oxidation reaction so as to trap the CO and the HC, making them react with O₂, an air- rich, lean carburetion is needed but, in this way, it wouldn't be possible to eliminate the nitric oxides.

It can be deduced that to attain the best condition, both the reduction and the oxidation relationship are required: the carburetion should not be lean or rich, but perfectly balanced or, more specifically, stoichiometric. The ideal air-petrol ratio is approximately 14.7 : 1 and is called the stoichiometric ratio. Under these conditions, the catalytic muffler achieves its maximum efficiency, eliminating 90% of the NO_x, 89% of the CO, and 91% of the HC. However, given that carburetion may be affected by atmospheric pressure and air humidity, it must be constantly adjusted to remain within its ideal conditions. For this reason, a lambda probe is used to measure the oxygen levels in the exhaust gas maintaining them at their ideal level, controlling the carburetion by means of a small computer. This system is known as "electronic injection". Presently, some manufacturers have introduced the so-called DPF (Diesel Particulate Filters) that are maintenance free and require no additives to periodically eliminate any deposits. According to the same manufacturers, fuel consumption and CO₂ emissions are similar to what would be obtained without the filter.

In any case, the catalytic mufflers and the special filters are unable to efficiently reduce the emission of harmful substances into the environment, also due to the extensive maintenance they require.

The main purpose of the following industrial invention is to create a multistage condensation reactor that will eliminate polluting emissions and improve the overall efficiency of internal combustion engines powered with petrol, Diesel or any other fuel that, with the comburent air, forms the mix and that generates mechanical energy in the stoichiometric process.

Another purpose of this invention is to create a device that offers high quality operating safety, is self-cleaning, does not require maintenance over time, has enhanced reliability and has no holes or cavities that during operation and over the years may become clogged.

Another purpose of this invention is to propose a reactor that can be used instead of the pre-catalyser, or trivalent or tetravalent catalyser. Therefore, the specific subject of this invention is a 1. Multistage condensation reactor within sonic cavity for treating exhaust gas of internal combustion engines, characterised in that it comprises a body provided, on one end, with couplings means with the gas exhaust duct, and on the other end, with a jet head or outlet, said body being hollow internally so as to create a gas passage line from said means for coupling with the exhaust duct to said outlet head, the path inside said body being comprised, from the end coupling with said container toward said jet head, of a first converging zone, a diverging zone and a second converging zone, in proximity of said jet head, internally to said passage in the body, being provided an internal flow diffuser; the whole in such a manner as to condensate said exhaust gas at the outlet from said jet head.

Always according to the invention, between said first converging zone and said diverging zone, a duct may be present to supply a chemical additive, with such chemical additive designed to convert the nitric oxides

(NO_x) into nitrogen and water vapour, and with said chemical additive contained in a reservoir. Preferably, according to the invention, said reactor can include a pump installed between said duct and said reservoir.

Additionally, according to the invention, said internal diffuser can consist of a first part with a constant section and a second part with a tapered section.

Again, according to the invention, said internal diffuser can be joined to said jet head by a sleeve, forming a reaction chamber designed to mix the exhaust gas particles .

An advantage, according to the invention, is that holes to convey the vapour flow directly to the jet head can be present on said coupling.

Always according to the invention, three equally- spaced holes can be present on said coupling.

Again according to the invention, said internal diffuser can include, at the bottom, a thermodynamic flow head located on the opposite extremity of said coupling, designed to mix the flows and to attenuate high frequency audio tones .

Additionally, according to the invention, said internal diffuser can be hollow and include, laterally, at least one ring.

Preferably, according to the invention, a constant section segment can be present between said first converging zone and said second diverging zone.

Again, according to the invention, said reactor can include an external diffuser cone located above said head, creating a diverging segment to convey the gas .

Preferably, according to the invention, said external diffuser cone can include an attachment designed to connect exhaust gas diagnostic testing equipment .

Always according to the invention, said diagnostic equipment can include an analyser and at least one probe. An advantage, according to the invention, is that said equipment coupled to said gas exhaust duct can include a flange, and/or holes for screws and/or a joint .

Preferably, according to the invention, said body can be made in two parts, a lower part and an upper part respectively, that can be mutually coupled by screwing, insertion, etc., while a gasket can also be included in the coupling between said two parts .

An illustrative but not limiting description of the invention will now be provided, according to its preferred forms of construction, with particular reference to the figures indicated in the attached drawings , in which : figure 1 illustrates a cutaway view of the body of the reactor according to this invention; figure 2 illustrates the quality of the gas flows inside said reactor according to figure 1; figure 3 illustrates a diagram of the speed, pressure and areas of the section of the reactor according to figure 1; figure 4 illustrates a section of a thermodynamic outflow head; and figure 5 illustrates a second form of construction of the reactor according to this invention.

With reference to figure 1, it is possible to observe one section of the reactor as referenced in this invention.

Said reactor is hollow internally and includes a section for the exhaust gas that can be divided into four parts or main zones, arranged in series:

• converging segment (sections of area Al, i.e. point A, with reference to section 1, - B3) : in which the gas flow encounters a constant section inlet duct 1, that can be screwed on or welded to the body of the reactor, and a lead-in cone 2, in which the section gradually reduces. This is followed by a constant section segment 3, which has been designed to mount a supply duct 18, whose function will be described herein;

• diverging segment (sections of area B3-C4) : this is the initial part of the reactor body.

It has a truncated-cone shape with a part that can be coupled to the final part of the reactor body, by means of threading, screwing or insertion, etc., that forms the head of the reactor. Inside, it includes an internal flow diffuser cone 7, designed to create special segments to the exhaust gas within said diverging area B3 - C4 ;

. converging segment (sections of area C4-D6) : this comprises the second part of the reactor body where the thermodynamic outflow head 13 will be screwed on. A silicone elastomer gasket 9 is installed in the coupling between said two parts of the reactor body; • converging segment and external diffusion (sections of area D6-E12) : this segment contains the reactor cap that identifies the volume 10. An external diffuser cone 12, through which the gas is expelled into the atmosphere, is located above said cap. The external diffuser cone 12 also includes a lead-in 11. As can be observed, the reactor body is specially contoured and, on the extremity relative to the constant section segment 1 relative to the converging zone A1-B3, includes a coupling flange (not visible in the figure) . Said flange can be coupled using screws in special holes, or through a stainless steel joint or with an elastomer gasket for the connection to the exhaust gas duct.

As previously mentioned, a thermodynamic outflow jet head 13 is present on the second extremity of said body .

Said reactor is completely built in stainless steel with enhanced corrosion resistance, preferably, according to the European designation, NF EN 1088-2, denomination X6CrNiTi 18-10 AISI 321 UNS S32100.

The interior of said reactor is hollow so as to create a line in axis for conveying the exhaust gas from the coupling equipment with the gaseous flow piping-duct to the outlet head 13.

The section inside said body starts from the coupling end with said inlet piping at the lead-in pressure toward said jet head 13. The reduction of the section between the lead-in cone 2 and the zone with diverging area 4 or the reactor head creates a partial separation between the first stage and the second stage of the reactor 1.

The internal flow diffuser 7 is attached to a coupling or expansion chamber 16 so as to form a single body. Said reaction-expansion chamber 16 contains a thread 14 for screwing said thermodynamic outflow head

13.

The top part of the internal flow diffuser 7 includes an expansion-reaction chamber 16 open on the sides with holes 15, which are preferably spaced 120° apart from each other, designed to allow the fluid (gas) to flow directly to the jet head 13 (thermodynamic outflow) . The interior of said flow diffuser 7 has a canal 17 with a constant section in axis with the reactor body and with the trajectory of the flow, and a diverging circular canal 6. Said canal 17 terminates in the extremity of the expansion-reaction chamber 16 with a tapered end, created through a small diverging segment that opens to the aforementioned chamber 16 to recompress the fluid. Said canal 17 is used to optimise the process in the reaction chamber 16, generating strong turbulence inside the reactor head.

For weight and other reasons, the flow diffuser has a hollow interior, a truncated-cone section, and/or different sections, and is built by means of moulding or similar methods, with a canal or small tube inside, as described in greater detail herein.

The flow diffuser can be equipped with one or more rings with a special positioning ring nut for screwing and/or welding, depending on type and dimensions. For example, for large propulsors, rings similar to washers will be used: the inner diameter of the central hole is equal to the cone section in which said rings will be inserted as a separating partition. Said separating partition is used to form the chambers-stage along the internal diffuser cone 7, for the purpose of modifying the response pattern of the fluid-dynamic parameters, of the perturbed zone, separated by an unperturbed zone, since it is possible to control the magnitude of the perturbations, i.e. the wave fronts (Mach waves) that propagate in the developed region of the reactor. To this regard, multistage contouring, for some applications, can also be used to optimise the noise due to the high frequencies in the exhaust duct.

It can be deduced that such a multistage application can be used to prevent residual combustion products from pooling, as occurs in existing mufflers. In the minimum taper point 4 of the segment B3-C4 of the internal diffuser cone 7, a small threaded coupling, with a special thread, makes it easier to screw on a thermodynamic flow head 5. With reference to figure 2, it can be observed that said flow head 5 is used to mix the two flows, designated as fl and f2, as a result of the difference in volumetric mass in the volume indicated with reference 19, in axis in the reactor. This also significantly reduces the noise in the duct.

The flow head 5 can be calibrated and contoured according to the frequency response of the noise to be attenuated in the cavity. Generally, it is designed to increase the efficiency at the low frequencies (low- pass filter) , being able to optimise the audio band (fluid-dynamic hiss) , according to the frequency interval preferred by the manufacturer, also depending on the type of propulsor. Said previously described thermodynamic flow head 5 can also be designed to optimise the frequency response with respect to the outflow head 13.

The outflow head 13 is connected to the flow diffuser cone body inside the reactor 7 through the coupling 8, by means of screwing or insertion, and/or welding of the two units .

The outlet diffuser cone 12 of the reactor coupled to the reactor head, could be screwed to the exterior of the outflow head 13, or welded to the reactor head, extending the duct up to the outlet terminal, depending on the specific case.

Said external flow diffuser cone 12 will be personalised according to the specific needs of the manufacturer, forming a particularly attractive discharge terminal, the interior of which contains, as already mentioned, the special thermodynamic outflow head. From an operating viewpoint, consider figure 3, which illustrates the various segments and sections, in addition to the speed W, area S and pressure P graphs. It can be observed that the fluid, flowing into the segment from Al to B3, begins to accelerate, thanks to the narrowing of the throat marked on the graph with AgI, while the pressure begins to drop, leading to a subsequent increase in speed, with the process completed in segment B3-C4, in which the quality of the physical parameters being analysed is clearly visible.

It can be deduced that in segment A1-C4, the speed W of the fluid reaches maximum values, while the pressure decreases to lower values (rate of descent) . This is caused by the variation in the section of the reactor body.

In segment C4-D6, due to the narrowing of the section at point Ag2 (area of the section marked as 2) , owing to the maximum diffuser taper 7, a second converging segment is created (C4-D6) whose section reverses the homogeneous quality of the flow being analysed.

The speed in the converging section of segment C4-Ag2 begins to decrease, while the pressure tends to increase due to the effect of the section in the reactor head, which decreases.

In section D6-E12 of the reactor, the two flows (fl-f2) flow into the expansion-reaction chamber 16. Flow fl passes through canal 17, while f2 flows into the circular canal 6. Flow f2 is forced to channel through the three head holes 15 spaced 120° apart, while flow 1 passes through the central canal 17. Due to the difference in mass, volume and speed, a highly turbulent and whirling motion with elevated rotational speed is created inside the expansion-reaction chamber

16.

The perturbations within the supersonic speed range in the aforementioned reaction chamber 16 of the reactor cause the gas particles to be mixed intensely. This implies that there is a turbulent motion, heat and molecular thermal diffusion. Such kinematic behaviour condenses the vapours of the gas involved in the chemical reaction process. Another significant contribution is provided by the micronized additive-reagent that converts the NO_x

(NO and NO₂) of the gaseous emissions into what are inert compounds for the environment, such as N₂ and water vapour. This additive, through a vacuum, is suctioned off from the previously described supply duct 18.

The channelled fluid, in the top of the reactor, volume 10, after being forced to flow through the previously mentioned segments, again encounters a new contour at the outlet created by the jet head 13 which is specially contoured according to the specific applications .

In segment D6-E12, where the diverging outlet cone 12 is located, the fluid is placed under conditions that are approximately equal to the lead-in pressure in the segment A1-B3, since the fluid must deal with the discharge pressure.

The trend of the pressure P, area A and speed W curves is similar to the one at the reactor inlet. Based on an additional analysis of the graphs shown in figure 3, it can be observed that in the converging ducts (for which Δ is considered a variation indicator, we have ΔS<0) and for subsonic motions at the lead-in (Ma<l) we have ΔW>0, i.e. an increase in speed with a corresponding decrease in fluid pressure, while in the diverging ducts (ΔS>0) and always for subsonic motions, there will be a decrease in speed (ΔW<0) with a corresponding increase in pressure.

For supersonic motions (Ma>l) and converging ducts (ΔS<0) , there will be a decrease in speed (ΔW<0) and an increase in pressure (ΔP>0) , while in diverging ducts there will be an increase in speed and a corresponding decrease in pressure.

We can say that in area A1-B3 of the duct segment, the fluid travels under subsonic conditions and that in point AgI (sonic area) it attains the speed of sound. In duct segment B3-D6, the fluid maintains its supersonic speed, while in segment D6-E12 it again decreases to subsonic speed, passing through point Ag2 at sonic speed (Ma=I) .

It can be deduced that in duct 4 there is a heterogeneous fluid, not constant over time, whose speed and pressure parameters vary according to engine rpm. It is easy to understand that the acceleration causes the fluid inside the reactor to acquire the previously described speed trends based on the internal contouring of the reactor, and on the reference area of the predefined sections.

For what concerns the installation of the reactor on medium and high-powered propulsors, such as road tractors, etc., for high exhaust gas flow rates, multiple reactors can be easily implemented in parallel, in a coupling manifold, and in the terminal segment of the outlet duct (such as after the silencer) . For specific applications the reactor can also be equipped with pressure and/or temperature transducers .

The process can also be controlled optically by- means of a specially-designed micro video-camera (not shown in the figures) installed in a well protected by tempered glass with high mechanical resistance.

The transduced analog/digital signals will be transmitted over a multifunction cable (not shown in the figures) , supplying the signal to the control logic and/or to an onboard monitor. In some cases, the process will be managed by a satellite system or an IDS

{Interactive Driving System), since it is possible to design a special signal synoptic control, or by an onboard computer with diagnostics control functions . Again, by means of an integrated expert electronic system, we can graphically represent the parameters referenced in the exhaust gas tests, using probes installed on the outlet of the thermodynamic outflow head, in lead-in 11. The measured parameters could also be supplied as graphs to controlling authorities or those in charge of road safety, such as the Highway Patrol, Tax Police, city law enforcement officers, etc.

For applications on medium and high-powered propulsors, the reactor, as already mentioned, can also be equipped with a special supply duct 18 through which a natural chemical additive - a micronized additive pre-diluted in percentages to be defined - can be introduced into the reactor. The flow of said chemical substance is normally supplied by means of a vacuum from a special reservoir and automatically forced into a critical region of the reactor. In any case, the reactor can also be equipped with a small circulator or jet pump (not shown in the figures) with a modulating drive controlled by the electronic system logic circuit that manages the electronic injection {Fuel Injection Control) .

The main purpose of the micronized chemical additive is to convert the nitric oxides (NO_x) into nitrogen and water vapour, i.e. into substances already found in nature . In fact, the nitric oxide emissions (NO_x) must be reduced (according to the current regulations) by 30%, from 5 to 3.5 g/KWh, while the particulate emissions (PM) must decrease from 0.1 to 0.02 g/KWh, i.e. a reduction of no less than 80%. This treatment offers truly absolute safety, since it eliminates a significant percentage of the outlet gas emissions from the exhaust duct.

In addition to offering the aforementioned advantages, the referenced reactor also helps to improve counter-pressure (exhaust back pressure) , due to the fluid-dynamic resistance that obstructs the outflow of the exhaust gas, the presence of areas of confluence between the ports of the various cylinders (junctions-connections) and the serial filtering stages, like the oxidising pre-catalyser, the reducing catalyser, the sound-absorbing mufflers, the "DPF" {Diesel Particulate Filters) or the "DE-Nox" filters, soon available under Euro 5.

Exhaust back pressure phenomena occur not only due to application of the aforementioned stages. In fact, the junctions in which the exhaust gases converge, the type of which depends on the grouping in the manifold, before coming together into a single pipe, introduce a reflection like the one that occurs when the exhaust terminal ends in the direction of the external environment.

Therefore, a vacuum sonic wave returns in the duct toward the exhaust valve that generated it .

Then, the exhaust values open at various instants, generating very different reflection phenomena. Usually, for some applications, the two manifolds remain independent to provide greater power. Finally, in order to tune a propulsor within certain limits, the supply, depending on the foreseen use, is rather complex.

The reactor, according to this invention, and depending on the aforementioned installation situations, can increase propulsor power: i.e. higher torque and increased performance, thanks to the recovery of load losses with reference to the series- installed filtering stages, and the losses due to manifold connections. The reactor radically reduces the exhaust back pressure in the duct due to the "extractive" effect of the sonic cavity that, through a vacuum, accelerates the motion, transiting from subsonic speed in the converging segment C4-D6 to supersonic speed in the diverging segment D6-E12 of the reactor. At high engine rpm, in the thermodynamic outflow head 13, the heterogeneous gases treated by the reactor can also flow at "Mach 1", at the same speed as a jet, i.e. at more than 340 m/s. It can be seen that the outlet speed can be determined in advance based on a fluid-dynamic model, with reference to the dimensional characteristics of the reactor body and of the thermodynamic outflow head (jet) and by modifying the contouring according to the result to be obtained, such as on a V8, VlO or V12. Naturally, it is possible to optimise the performance based on precise, specially designed mathematical models, utilising appropriate simulation platforms.

Figure 4 includes a perspective of a section of the thermodynamic outflow head, in which we can observe in particular the thread 14 for the coupling to the reactor body. There is also a limit ring 14' , that divides the segment to be screwed to the reactor body and to the outlet diffuser cone 12.

As can be observed the thermodynamic outflow head has two internal segments, converging 13' and diverging 13'' respectively, designed to accelerate the gas expulsion speed.

Finally, figure 5 shows an additional reactor construction design in which the internal flow diffuser cone 7 is equipped with one or more rings 20 with a special positioning ring nut for screwing and/or welding. Said rings create separating partitions, making it possible to form "chambers-stage" along the internal diffuser cone 7, in order to modify the response pattern of the fluid-dynamic parameters, of the perturbed zone, separated by an unperturbed zone, being able to control the magnitude of the perturbations, i.e. the wave fronts (Mach waves) that propagate in the reactor. Thus, multistage contouring can be used to optimise the noise due to the high frequencies in the exhaust duct. This solution can be used to make the "chambers-stage" self-cleaning, thanks to the gaseous flow, preventing residual combustion products from pooling, unlike what always occurs in existing mufflers. An illustrative but not limiting description of this invention has been provided, according to its preferred forms of construction, but it remains understood that variations and/or modifications can be made by sector experts without straying beyond the relative protection environment, as defined in the attached claims.

Claims

1. Multistage condensation reactor within sonic cavity for treating exhaust gas of internal combustion engines, characterised in that it comprises a body provided, on one end, with couplings means with the gas exhaust duct, and on the other end, with a jet head or outlet, said body being hollow internally so as to create a gas passage line from said means for coupling with the exhaust duct to said outlet head, the path inside said body being comprised, from the end coupling with said container toward said jet head, of a first converging zone, a diverging zone and a second converging zone, in proximity of said jet head, internally to said passage in the body, being provided an internal flow diffuser; the whole in such a manner as to condensate said exhaust gas at the outlet from said jet head.

2. Reactor according to claim 1, characterised in that between said first converging zone and said diverging zone, there is a duct to supply a chemical additive, with such chemical additive designed to convert the nitric oxides (NO_x) into nitrogen and water vapour.

3. Reactor according to claim 1, characterised in that said chemical additive is contained in a reservoir.

4. Reactor according to claim 3, characterised in that there is a pump between said duct and said reservoir.

5. Reactor according to one of the previous claims, characterised in that said internal diffuser consists of a first part with a constant section and a second part with a tapered section.

6. Reactor according to one of the previous claims, characterised in that said internal diffuser is joined to said jet head by a sleeve, forming a reaction chamber designed to mix the exhaust gas particles.

7. Reactor according to claim 6, characterised in that holes are provided on said sleeve to convey the vapour flow directly to the jet head.

8. Reactor according to claim 7, characterised in that three equally spaced holes are provided on said sleeve.

9. Reactor according to one of the previous claims, characterised in that said internal diffuser includes, at the bottom, a thermodynamic flow head located on the opposite extremity of said coupling, designed to mix the flows and to attenuate high frequency audio tones .

10. Reactor according to one of the previous claims, characterised in that the interior of said diffuser is hollow.

11. Reactor according to one of the previous claims, characterised in that said internal diffuser includes, laterally, at least one ring.

12. Reactor according to one of the previous claims, characterised in that a segment with a constant section is present between said first converging zone and said second diverging zone.

13. Reactor according to one of the previous claims, characterised in that it includes an external diffuser cone located above said head, creating a diverging segment for conveying the gas .

14. Reactor according to claim 13, characterised in that said external diffuser cone includes an attachment designed to connect exhaust gas diagnostic testing equipment .

15. Reactor according to claim 14, characterised in that said diagnostic testing equipment includes an analyser and at least one probe .

16. Reactor according to one of the previous claims, characterised in that said coupling devices with said gas exhaust duct include a flange.

17. Reactor according to one of the previous claims, characterised in that said coupling devices with said gas exhaust duct provide holes for screws and/or a joint.

18. Reactor according to one of the previous claims, characterised in that said body is made of two parts, a lower part and an upper part respectively, that can be mutually coupled by screwing, insertion, etc.

19. Reactor according to claim.18, characterised in that a gasket is provided in the coupling between said two parts.

20. Reactor according to each of the previous claims substantially as illustrated and described.