TECHNICAL FIELD
[001] The present disclosure generally relates to the field of automobiles. Particularly, but not exclusively, the present disclosure relates to an exhaust gas treatment system for controlling NOx emissions. Further, embodiments of the present disclosure describes method for treating exhaust gases by incorporating fluid dosing unit (FDU) and a DeNOx catalyst.
BACKGROUND
[002] Nowadays the pollution generated by burning of fuel in Internal Combustion (IC) engines is increasing exponentially. The burning of fuel specifically diesel in IC engines give rise to emission of pollutants in the form of carbon mono oxides, nitrous oxides (NOx) and particulate matters. Therefore, the norms are made strict towards the using of internal combustion engines to prevent emission of pollutants in the environment. The manufacturers are now focusing on the systems and methods to reduce emission of pollutants from IC engines. Because of increased awareness of environment and health hazards, the emission limit of the said pollutants from a diesel engine have become more stringent. The amount of NOx and PM emitted from a diesel engine have been regulated based on application type, engine power, size of the engine etc.
[003] In order to meet the NOx emission legislation, various strategies are applied such as introducing small amount of exhaust gas recirculation (EGR) in combination with exhaust after treatment systems such as selective catalytic reduction (SCR) or lean NOx trap (LNT) for controlling NOx emission. In SCR technology, NOx is reduced by injecting reductant, commonly used as ammonia (NH3) which is a product of urea (NH2CONH2) decomposition while in LNT technology, NOx is being adsorbed during lean operation and reduced during desorption on injecting reductants such as CO, HC produced by external fuel injector or by late post injection.
[004] Further, the state of art technologies described above are commercially used and aftertreatment used to control NOx emission are almost 2.5 to 3 times higher than that of

engine displacement. The complexity of the conventional system described as state of art technologies may increase cost, packaging and overall size of the system when applied to diesel engines.
[005] The present disclosure related to exhaust gas treatment is directed to overcome one or more limitations stated above or any other limitations associated with the prior art.
SUMMARY OF THE DISCLOSURE
[006] One or more shortcomings of conventional systems are overcome, and additional advantages are provided through the system as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
[007] The present disclosure relates to an exhaust gas treatment system offering a NOx reduction technology that decreases the system packaging by avoiding the use of SCR / LNT catalyst unit and overcome the complexity introduced in the above described state of art technologies. The NOx reduction technology in accordance with the disclosure includes a fluid dosing unit (FDU), an exhaust gas recirculation unit, exhaust aftertreatment system and EGR control valve. The partitioning of exhaust gas to a DeNOx catalyst placed downstream of fluid dosing unit (FDU) may also have a heating arrangement like glow plug or any other means of heating, an exhaust gas recirculation (EGR) unit disposed downstream of DeNOx catalyst, the resultant EGR being referred as Diluent Rich EGR (D-EGR) and remaining exhaust is passed through an oxidation catalyst coupled with particulate oxidation catalyst (POC) or Diesel Particulate filter (DPF).
[008] The exhaust gas treatment system comprising an engine having an intake manifold and an exhaust manifold, an exhaust gas recirculation (EGR) unit. The EGR unit comprises control valves adapted to control flow of exhaust gases. A DeNOx unit connected to the exhaust manifold, having a primary DeNOx system and a secondary exhaust gas treatment system. The primary DeNOx system comprises a fluid dosing unit which is fluidically

connected to the exhaust manifold of the engine. A catalyst coupled at outlet of the fluid dosing unit. The fluid dosing unit is configured to inject atomized fluid into the exhaust gases, and amount of the fluid injected is controlled by an ECU.
[009] Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered as a part of the claimed disclosure.
[010] In one non-limiting embodiment of the present disclosure, the EGR unit is fluidically connected at downstream of the primary DeNOx system.
[Oil] In an embodiment, the exhaust gases from the primary DeNOx system are circulated through EGR unit into an EGR port or an air intake port by actuation of the control valves.
[012] In an embodiment, the control valve is adapted to actuate at part load conditions and the control valve is adapted to actuate at low load and high load conditions.
[013] In an embodiment, the control valve facilitates flow of EGR gas to the engine through EGR port at part load conditions.
[014] In an embodiment, the fluid injected into the exhaust gases contains diesel or gasoline or alcohol or water or fluid compatible additives or their combination thereof.
[015] In an embodiment, the injection of atomized fluid by fluid dosing unit facilitates changes in the exhaust characteristics like leading to reduction in temperature of exhaust gases or leading to diluent rich exhaust gases to bring down generation of thermal NOx inside the engine reduction in temperature of exhaust gases.
[016] In an embodiment, the fluid dosing unit comprises a nozzle, a spraying unit, a pumping unit, and an evaporating unit.
[017] In an embodiment, the secondary exhaust gas treatment system comprising a diesel oxidation catalyst unit and a particulate oxidation catalyst.

[018] In an embodiment, the diesel oxidation catalyst unit facilitates the oxidation of carbon monoxide, unburnt hydrocarbons and particulate matter contained in the exhaust gases.
[019] In an embodiment, the ECU controls the amount of fluid injected onto the exhaust gases based on engine parameters.
[020] In an embodiment, the EGR port is adapted to inject the EGR gases into the engine to facilitate reduction in generation of NOx.
[021] In another preferred embodiment, an exhaust gas treatment method for controlling NOx emissions, comprising steps of: circulating exhaust gases ejected from an exhaust manifold of an engine to a DeNOx unit. The DeNOx unit having a primary DeNOx system and a secondary exhaust gas treatment system; injecting of atomized fluid in controlled amount into the exhaust gases governed by a fluid dosing unit and passing the exhaust gases through a catalyst coupled at outlet of the fluid dosing unit; circulating a portion of exhaust gases from the primary DeNOx system into a secondary exhaust gas treatment system before discharging into atmosphere, and recirculating the treated exhaust gases through an exhaust gas recirculation (EGR) unit into the engine.
[022] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.
[023] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects and features described above, further aspects and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[024] The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a mode of use, further objectives and

advantages thereof, will best be understood by reference to the following detailed description of an embodiment when read in conjunction with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:
[025] FIG.l illustrates a flow chart of exhaust gas treatment system, in accordance with an embodiment of the present disclosure;
[026] FIG. 2 illustrates a flow chart of exhaust gas treatment system, in accordance with another embodiment of the present disclosure;
[027] FIG. 3 illustrates a graph disclosing effect of treatment system on NOx reduction at high load conditions;
[028] FIG. 4 illustrates a graph disclosing effect of treatment system on NOx reduction at part load conditions;
[029] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the objective of the disclosure described herein.
DETAILED DESCRIPTION
[030] While the embodiments in the disclosure are subject to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[031] It is to be noted that a person skilled in the art would be motivated from the present disclosure and modify an exhaust gas treatment system, which may vary in accordance with fuel burning capacity of different engines. However, such modifications should be

construed within the scope of the disclosure. Accordingly, the drawings show only those specific details that are pertinent to understand the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
[032] The terms "comprises", "comprising", or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a system and method that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, method, or assembly, or device. In other words, one or more elements in a system or device proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[033] Accordingly, the present disclosure relates to an exhaust gas treatment system for reducing amount of NOx in the exhaust gases. The exhaust gas treatment system is assembled with an exhaust manifold of existing engine preferably diesel engine. The engine burns fuel to produce power and eject exhaust gases into the atmosphere. The exhaust gases contain particulate matter (PM), nitrous oxides (NOx) and unburnt hydrocarbons resulting in spreading of pollutants into the atmosphere. The convention EGR systems have been assembled with the engines do not significantly reduce the emission of pollutants into the atmosphere. In accordance with the present disclosure, the exhaust gas treatment system is disclosed. The system comprises an engine having an intake manifold and an exhaust manifold. The engine disclosed in the present disclosure is preferably a diesel engine. Further, the exhaust gas treatment system comprises an exhaust gas recirculation (EGR) unit, wherein the EGR unit comprises control valves adapted to control flow of exhaust gases. A DeNOx unit connected to the exhaust manifold comprising a primary DeNOx system and a secondary exhaust gas treatment system. The primary DeNOx system comprises a fluid dosing unit which is fluidically connected to the exhaust manifold of the engine. A catalyst is coupled at outlet of the fluid dosing unit. The fluid dosing unit is configured to inject atomized fluid into the exhaust gases and the amount of fluid injected is controlled by an ECU.

[034] The primary DeNOx system facilitates treatment of exhaust gases which is required to recirculate into the engine through EGR unit to facilitate combustion of fuel. The atomized fluid injected by the fluid dosing unit into the exhaust gases comprises any one of diesel, gasoline, alcohol or water. Further, their combination can also be injected in a predefined ratio into the exhaust gases. The injection of atomized fluid results in change in exhaust gas characteristics like reduction in temperature of exhaust gases and other changes, which facilitates significant reduction in NOx in the exhaust gases. Further, the secondary exhaust gas treatment system may be assembled at different locations in order to treat the exhaust gases before ejecting them into the atmosphere. The secondary exhaust gas treatment system comprising a diesel oxidation catalyst unit and a particulate oxidation catalyst.
[035] The following paragraphs describe the present disclosure with reference to Fig.l and Fig. 2. In the figures, the same element or elements which have similar functions are indicated by the same reference signs.
[036] An exhaust gas treatment system (100) comprises an engine (10), an exhaust gas recirculation (EGR) unit (11) and a DeNOx unit (12). The system (100) can be assembled with the existing engines (10), preferably diesel engines to control NOx emissions from the engine (10). Further, the engine (10) comprising an intake manifold (101) and an exhaust manifold (102). The intake manifold (101) comprises plurality of inlets in a diesel engine to allow flow of air into combustion chamber of the engine (10) where air and fuel mixture is combusted. The EGR unit (11) comprises plurality of control valves (20, 22) adapted to control flow of recirculated exhaust gases. The control valves (20, 22) are actuated based on the engine operating parameters like engine speed and load. The system (100) does not use any selective catalytic reduction catalyst and/or urea injection system or making the assembly compact and cost effective.
[037] In an embodiment of the present disclosure, the DeNOx unit (12) being connected to the exhaust manifold (102) comprises a primary DeNOx system (121) and a secondary exhaust gas treatment system (122). The primary DeNOx system (121) comprises a fluid dosing unit (1211) and a catalyst (1212). The fluid dosing unit (1211) is fluidically

connected to the exhaust manifold (102) of the engine (10). The catalyst (1212) coupled at outlet of the fluid dosing unit (1211) may include lean NOx Trap, NOx absorber catalyst, Passive NOx adsorbers (PNAs) or three-way catalyst in form of DeNOx catalyst unit. The fluid dosing unit (1211) may comprise a nozzle, a spraying unit, a pumping unit and an evaporating unit controlled by the ECU. The fluid injected by the fluid dosing unit (1211) contains diesel or gasoline or alcohol or water or fluid compatible additives or their combination thereof.
[038] In an embodiment of the present disclosure, the secondary exhaust gas treatment system (122) comprises a diesel oxidation catalyst unit (1221) and a particulate oxidation catalyst unit (1222). The diesel oxidation catalyst unit (1221) facilitates the oxidation of carbon monoxide, unburnt hydrocarbons and particulate matter contained in the exhaust gases. The diesel oxidation catalyst unit (1221) comprises: a substrate, a washcoat layer disposed on substrate, wherein the washcoat layer comprises platinum group metal (PGM) and support material. The particulate oxidation catalyst (1222) comprises: a substrate prepared from a structured wire mesh or from cordierite extruded in structured form to capture particulate emitted from the engine (10). A diesel particulate filter may be used instead of particulate oxidation catalyst (1222) if higher reduction in particulate matter is required.
[039] In another embodiment of present disclosure, a part of exhaust gases ejected by the engine (10) through exhaust manifold (102) enter the fluid dosing unit (1211) as shown in Fig, 1. The fluid dosing unit (1211) is configured to inject atomized fluid into the exhaust gases to facilitate reduction in NOx content. The fluid dosing unit (1211) is configured to inject atomized fluid into the exhaust gases to facilitate reduction in NOx content. The amount of fluid injected into the exhaust gases is controlled by an Electronic Control Unit (ECU) and may vary in accordance with the engine operating parameters. The injection of atomized fluid into the exhaust gases facilitates reduction in temperature. The exhaust gases are then allowed to pass through the catalyst (1212) to facilitate oxidation of pollutants into harmless oxides. The part of exhaust gases ejecting from the catalyst (1212) are diluent rich in nature as it contains atomized fluid particles injected by the fluid dosing

unit (1211). The exhaust gases treated by the primary DeNOx system (121) is then allowed to recirculate through EGR unit (11) into the intake manifold (101) of the engine (10). The recirculated exhaust gases facilitates reduction in generation of NOx during combustion stage. The amount of recirculated exhaust gas entering in the engine (10) is controlled with the help of ECU (not shown in Fig.s). The ECU detects the engine parameters i.e. engine load, engine speed etc and operate the control valves (20, 22) accordingly. During low load and/or high load conditions the ECU actuates the control valve (22) to allow flow of the recirculated exhaust gases into intake manifold (101). Similarly, during part load conditions the ECU actuates the control valve (20) to allow the flow of recirculated exhaust gases into the engine (10) through EGR port (13). The EGR port (13) operates only at part load conditions, therefore providing at least two control valves (20, 22) facilitates proper recirculation of modified or fluid - treated exhaust gases in varying quantities according to the operating conditions of the engine to facilitate reduction in emission of NOx from the engine (10). The decrease in NOx emission may be due to temperature drop inside the engine (10) to decrease thermal NOx formation. The recirculation of exhaust gases through EGR unit (11) may vary from 0-30% by volume.
[040] In another embodiment of the present disclosure as shown in Fig. 1, a part of exhaust gases ejected from the exhaust manifold (102) is allowed to pass through the secondary exhaust gas treatment system (122). The part of exhaust gases initially pass through the diesel oxidation catalyst (1221) to facilitate oxidation of carbon monoxide, unburnt hydrocarbons and particulate matter contained in the exhaust gases. The oxidized exhaust gases is allowed to pass through a particulate oxidation catalyst (1222) or diesel particulate filter in order to reduce the amount of particulate matter contained in the exhaust gases before discharging the gases into atmosphere.
[041] In an embodiment of the present disclosure as shown in Fig.2, the exhaust gases ejected from the exhaust manifold (102) is allowed to pass through the primary DeNOx system (121). The exhaust gases are initially treated in primary DeNOx system (121) and then a part of gases is drawn and circulated through EGR unit (11) into the EGR port (13) or the air intake port (14) by actuation of the control valves (20, 22). The treated exhaust

gases from the primary DeNOx system (121) is utilized to reduce the temperature inside the engine (10) during combustion stage. The remaining part of exhaust gases after DeNOx unit (121) is passed through the diesel oxidation catalyst (1221) and particulate oxidation catalyst (1222) of the secondary exhaust gas treatment system (122) before discharging into the atmosphere. The treated exhaust gas from the primary DeNOx system (121) is further treated by means of diesel oxidation catalyst (1221) to facilitate further reduction in NOx content and particulate oxidation catalyst or diesel particulate filter (1222) to achieve desired reduction in particulate matter before discharging into atmosphere.
[042] In an embodiment of the present disclosure, a method of treating exhaust gases coming out from an exhaust manifold (102) of an engine (10) is disclosed. The method comprising steps of circulating exhaust gases from the exhaust manifold (102) to a DeNOx unit (12). The DeNOx unit (12) comprises a primary DeNOx system (121) and a secondary exhaust gas treatment system (122). The exhaust gases or a part of exhaust gases is then allowed to pass through a fluid dosing unit (1211) of the DeNOx system (121). The fluid dosing unit (1211) injects atomized fluid into the exhaust gases in order to alter characteristics of the exhaust gases. The amount of fluid injected being controlled by an ECU. The exhaust gases are then allowed to pass through a catalyst (1212) to facilitate reduction in NOx content. The treated exhaust gases ejected from the DeNOx system (121) are then allowed to recirculate through an EGR unit (11) into the engine (10). The EGR unit (11) comprises control valves (20, 22) governing the flow of exhaust gases in accordance with the engine operating parameters. Further, the remaining part of exhaust gases is allowed to pass through the secondary exhaust gas treatment system (122) to facilitate oxidation of pollutants and reduction in amount of particulate matter before releasing the exhaust gases into atmosphere. The secondary exhaust gas treatment system (122) may be located at outlet of the exhaust manifold (102) or at outlet of the DeNOx unit (121) as per the requirement.
[043] In an embodiment of the present disclosure, the effect of exhaust gas treatment system was evaluated on a diesel engine having power range in the range of 5 kW to 50 kW. The evaluation was carried out at steady state condition on eddy current test bench.

The engine was operated at various speed and load conditions with various combinations - without EGR, with conventional EGR, with the primary DeNOx unit at EGR port and with EGR unit at air intake shown in Fig. 3. high load conditions. The engine speed was maintained in the range of 1600 to 2200 RPM and more specifically to 1800 to 2000 RPM. The effect of exhaust gas treatment system was found significant on NOx emission when used in combination with the primary DeNOx system and secondary exhaust gas treatment system in comparison with conventional EGR. The NOx concentration without EGR was 895 ppm and on using conventional EGR, it was 756 ppm. The effect of EGR was not significant at this load condition and with the exhaust gas treatment by fluid dosing system was 292 ppm when directed through air intake port.
[044] In another embodiment of the present disclosure, the effect of exhaust gas treatment system was also evaluated on part load condition where engine speed was maintained in the range of 1600-3200 RPM and more specifically to 2500 to 2800 RPM and load was maintained in the range of 8 to 15 N-m and more specifically to 10 to 13 N-m. The effect of exhaust gas treatment system was found significant on NOx emission when used in combination with the primary DeNOx system and secondary exhaust gas treatment system as shown in Figure 4. The NOx concentration without EGR was 433 ppm and with conventional EGR, it was 209 ppm. The effect of primary fluid dosed DeNOx system further decrease NOx concentration from 209 ppm to 101 ppm.
[045] The exhaust gas treatment system as disclosed in present disclosure provides significant reduction in emissions of pollutants into the atmosphere. Further, the exhaust gas treatment system is effective upto 50% reduction of NOx content in the exhaust gases. The system does not use any selective catalytic reduction (SCR) catalyst and urea injection system making the assembly compact and cost effective. Further, the fluid dosing unit may inject fluid from nil to 60% or more fluid into the exhaust gases based on the fuel consumption. Thus, making the exhaust recirculation gases (EGR) rich in diluent to facilitate reduction in NOx generation in the engine during combustion.

[046] The exhaust gas treatment system in accordance with present disclosure can be applied in various form in an internal combustion engine, being it a diesel or gasoline or any other liquid or gaseous fueled engine because NOx generation is a problem of an internal combustion engine. The invention described with particular examples are exemplary in nature and not limited since other modifications will become apparent to the skilled person in the art up on study of drawings and the specifications.

Equivalents:
[047] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
[048] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together,

etc.). In those instances, where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claim

We claim

1.An exhaust gas treatment system (100) for controlling NOx emissions, comprising
an engine (10) having an intake manifold (101) and an exhaust manifold (102);
an exhaust gas recirculation (EGR) unit (11), wherein the EGR unit (11) comprises
plurality of control valves (20, 22) adapted to control flow of recirculated exhaust
gases;
a DeNOx unit (12) connected to the exhaust manifold (102), comprising a primary
DeNOx system (121) and a secondary exhaust gas treatment system (122);
wherein the primary DeNOx system (121) comprises a fluid dosing unit
(1211) which is fluidically connected to the exhaust manifold (102) of the
engine (10);
a catalyst (1212) coupled at outlet of the fluid dosing unit (1211);
the fluid dosing unit (1211) is configured to inject atomized fluid into the
exhaust gases, and amount of the fluid injected is controlled by an electronic
control unit (ECU).
2. The exhaust gas treatment system (100) as claimed in claim 1, wherein the EGR unit (11) is fluidically connected at downstream of the primary DeNOx system (121).
3. The exhaust gas treatment system (100) as claimed in claim 1, wherein the exhaust gases from the primary DeNOx system (121) are circulated through EGR unit (11) into an EGR port (13) or an air intake port (14) by actuation of the control valves (20, 22).
4. The exhaust gas treatment system (100) as claimed in claim 1, wherein the control valve (20) is adapted to actuate at part load conditions and the control valve (22) is adapted to actuate at low load and high load conditions.
5. The exhaust gas treatment system (100) as claimed in claim 1, wherein the control valve (20) facilitates flow of EGR gas into the engine (10) through EGR port (13) at part load conditions.

6. The exhaust gas treatment system (100) as claimed in claim 1, wherein the fluid injected into the exhaust gases contains diesel or gasoline or alcohol or water or fluid compatible additives or their combination thereof.
7. The exhaust gas treatment system (100) as claimed in claim 1, wherein the injection of atomized fluid by fluid dosing unit (1211) facilitates changes in the exhaust gas characteristics like leading to reduction in temperature of exhaust gases or leading to diluent rich exhaust gases to bring down generation of thermal NOx inside the engine.
8. The exhaust gas treatment system (100) as claimed in claim 1, wherein the fluid dosing unit (1211) comprises a nozzle, a spraying unit, a pumping unit, and an evaporating unit.
9. The exhaust gas treatment system (100) as claimed in claim 1, wherein the secondary exhaust gas treatment system (122) comprising a diesel oxidation catalyst unit (1221) and a particulate oxidation catalyst or diesel particulate filter (1222).

10. The exhaust gas treatment system (100) as claimed in claim 8, wherein the diesel oxidation catalyst unit (1221) facilitates the oxidation of carbon monoxide, unburnt hydrocarbons and particulate matter contained in the exhaust gases.
11. The exhaust gas treatment system (100) as claimed in claim 1, wherein the ECU controls the amount of fluid injected onto the exhaust gases based on engine parameters.
12. The exhaust gas treatment system (100) as claimed in claim 1, wherein the EGR port (13) is adapted to inject the EGR gases into the engine to facilitate reduction in generation of NOx.
13. An exhaust gas treatment method for controlling NOx emissions, comprising steps of:

circulating exhaust gases ejected from an exhaust manifold (102) of an engine (10)
to a DeNOx unit (12) comprising a DeNOx system (121) and a secondary exhaust
gas treatment system (122);
injecting of atomized fluid in controlled amount into the exhaust gases by a fluid
dosing unit (1211) and passing the exhaust gases through a catalyst (1212) coupled
at outlet of the fluid dosing unit (1211);
circulating a portion of exhaust gases from the primary DeNOx system (121) into
a secondary exhaust gas treatment system (122) before discharging into
atmosphere, and;
recirculating the treated exhaust gases through an exhaust gas recirculation (EGR)
unit (11) into the engine (10).