Claims:We Claim:
1. A Selective Catalytic Reduction (SCR) system (100) to detect the presence of a flammable liquid in a diesel exhaust fluid (DEF) tank (101), the system (100) comprising the DEF tank (101), a SCR module (102), a dosing module (103) placed upstream from the SCR module (102), a first temperature sensor (104) placed upstream from the dosing module (103), an Electronic Control Unit (ECU (105)), characterized in that system (100):
a second temperature sensor (106) placed downstream from the SCR module (102), said sensor adapted to communicate temperature recorded downstream from the SCR module (102) to the ECU (105).

2. The Selective Catalytic Reduction (SCR) system (100) to detect a flammable liquid in the DEF tank (101) as claimed in claim 1, where the ECU (105) is connected to the first (104) and the second temperature sensor (106).

3. The Selective Catalytic Reduction (SCR) system (100) to detect a flammable liquid in the DEF tank (101) as claimed in claim 1, where the ECU (105) is connected is connected to the dosing module (103).

4. A method to detect the presence of a flammable liquid in a diesel exhaust fluid tank (DEF) of a Selective Catalytic Reduction (SCR) system (100) , the system (100) comprising the DEF tank (101), SCR module (102), a dosing module (103) placed upstream from the SCR module (102), a first temperature sensor (104) placed upstream from the dosing module (103), a second temperature sensor (106) placed downstream from the SCR module (102) and at least an Electronic Control Unit (ECU (105)) , where the ECU (105) of a vehicle is capable of :
Recording temperature measured by the first temperature sensor (104);
Adding a pre-determined value of tolerance stored in the ECU (105) to the temperature measured by the first temperature sensor (104);
Recording temperature measured by the second temperature sensor (106);
Calculating a difference between the temperature measured by the second temperature sensor (106) and the temperature measured by the first temperature sensor (104) along with the added value of tolerance.
Sending a signal to the dosing module (103) based on the calculation.
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed

Field of the invention
[0001] The present disclosure relates to a system to detect the presence of a flammable liquid in the diesel exhaust fluid tank

Background of the invention
[0002] Selective Catalytic Reduction (SCR) is an emissions control technology system used in diesel engines. In this technology a liquid-reductant agent is injected into the exhaust stream of a diesel engine. The liquid reductant agent is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF) or Ad-blue. The DEF sets off a chemical reaction that converts Nitrogen Oxides (NOx) into nitrogen, water and tiny amounts of carbon dioxide (CO2), which is then expelled through the vehicle tailpipe.

[0003] DEF is stored in a tank mounted on vehicle and through hydraulics and dosing request based on NOx conversion efficiency requirements, DEF is dosed into the exhaust stream. There exists a high probability that during re-filling of DEF tank, instead of DEF, a flammable liquid like diesel is filled instead. In such case system would inject diesel into the exhaust stream. This could damage the system and lead to safety hazard due to uncontrolled burning of diesel in the exhaust line.

Brief description of the accompanying drawings
[0004] An embodiment of the invention is described with reference to the following accompanying drawings:
[0005] Fig. 1 depicts a Selective Catalytic Reduction (SCR) system (100) to detect the presence of a flammable liquid in the diesel exhaust fluid tank, and;
[0006] Fig. 2 depicts a method to detect the presence of a flammable liquid in a diesel exhaust fluid (DEF) tank of a Selective Catalytic Reduction (SCR) system (100).

Detailed description of the drawings
[0007] Figure 1 depicts a Selective Catalytic Reduction (SCR) system (100) to detect the presence of a flammable liquid in a diesel exhaust fluid DEF tank (101). The system (100) comprises the DEF tank (101), a SCR module (102), a dosing module (103) placed upstream from the SCR module (102), a first temperature sensor (104) placed upstream from the dosing module (103), an Electronic Control Unit (ECU (105)) and at least a second temperature sensor (106) placed downstream from the SCR module (102). The said second temperature sensor (106) is adapted to communicate temperature recorded downstream from the SCR module (102) to the ECU (105).

[0008] The ECU (105) is connected to the first and the second temperature sensor (106). The ECU (105) is further connected to the dosing module (103). In an embodiment, the SCR module (102) further comprises an Ammonia Slip Catalyst (ASC) Module.

[0009] The DEF tank (101) stores the diesel exhaust fluid which is also known as Ad-blue. It is a liquid reductant agent and usually automotive-grade urea. The SCR module (102) is a chamber where the selective catalytic reduction reaction takes place. A selective catalytic reduction reaction converts nitrogen oxides (NOx) into nitrogen, water and tiny amounts of carbon dioxide (CO2) using Ad-blue fluid, thereby reducing NOx emissions. The dosing module (103) controls the amount of Ad-blue that needs to be injected from the DEF tank (101) into the SCR module (102). The first temperature sensor (104) measures the temperature upstream from the dosing module (103) and sends the information to the ECU (105). The second temperature sensor (106) measures temperature downstream from the SCR module (102) and sends the information to the ECU (105).

[0010] Figure 2 depicts a method (200) to detect the presence of a flammable liquid in a diesel exhaust fluid (DEF) tank of a Selective Catalytic Reduction (SCR) system (100). The system (100) comprises the DEF tank (101), a SCR module (102), a dosing module (103) placed upstream from the SCR module (102), a first temperature sensor (104) placed upstream from the dosing module (103), a second temperature sensor (106) placed downstream from the SCR module (102) and at least an Electronic Control Unit (ECU (105)). In step 201, the ECU (105) records temperature measured by the first temperature sensor (104). In step 202, the ECU (105) adds a pre-determined value of tolerance stored in the ECU (105) to the temperature measured by the first temperature sensor (104). In step 203, the ECU (105) records temperature measured by the second temperature sensor (106). In step 204, the ECU (105) calculates a difference between the temperature measured by the second temperature sensor (106) and the temperature measured by the first temperature sensor (104) along with the added value of tolerance. In steps 205, the ECU (105) sends a signal to the dosing module (103) based on the calculation.

[0011] In step 202 the ECU (105) adds a pre-determined value of tolerance stored in the ECU (105) to the temperature measured by the first temperature sensor (104). The pre-determined value of tolerance is based on the nominal temperature increase by NOx conversion reactions using DEF or Ad-blue fluid. SCR reactions using Ad-blue are generally slightly exothermic in nature. However when a flammable liquid like diesel is used instead of Ad-blue these reactions are high exothermic. Hence the nominal increase in temperature due SCR reactions using Ad-blue in general are adjusted using a pre-determined tolerance value.

[0012] In step 204, the ECU (105) calculates a difference between the temperature measured by the second temperature sensor (106) and the temperature measured by the first temperature sensor (104) along with the added value of tolerance. If the liquid present in the DEF tank (101) is a flammable liquid instead of ad-blue, it will cause an highly exothermic reaction in SCR module (102). For example a flammable liquid like diesel is mistakenly added in the DEF tank (101). This would lead to an highly exothermic reaction due to oxidation of diesel in the SCR module (102) causing the temperature downstream the SCR module (102) to rise. Hence the temperature measured by the second temperature sensor (106) will be more than the first temperature sensor (104).

[0013] The auto ignition temperature of diesel is around 210 degree Celsius and DEF is injected in the SCR module (102) by the dosing module (103) at temperatures equal to or above 180 degree Celsius. At temperatures above 210 degree Celsius, due to injection of diesel instead of ad-blue, most of the diesel would burn inside the exhaust stream (107). At temperatures between 180 and 210 degree Celsius, diesel would enter SCR module (102) and still get oxidized due to presence of SCR catalyst in the SCR module (102). In both the cases, temperature measured by the second temperature sensor (106) would be more than the first temperature sensor (104).

[0014] In steps 205, the ECU (105) sends a signal to the dosing module (103) based on the calculation. If the difference between the temperature measured by the second temperature sensor (106) and the temperature measured by the first temperature sensor (104) along with the added value of tolerance is negative, there have been no large exothermic reaction in the SCR module (102). It means there is no flammable liquid in the DEF tank (101). If the difference between the temperature measured by the second temperature sensor (106) and the temperature measured by the first temperature sensor (104) along with the added value of tolerance is positive, this means there have been highly exothermic reactions in the SCR module (102). It indicates that the fluid present inside the DEF tank (101) is a flammable liquid like Diesel. Hence the ECU (105) send a signal to the dosing module (103) to stop further injection of DEF fluid in the SCR module (102).

[0015] This idea to develop a Selective Catalytic Reduction (SCR) system (100) to detect the presence of a flammable liquid in the diesel exhaust fluid tank helps us recognize a safety hazard and further prevent uncontrolled burning of a flammable liquid in the SCR system (100). The uncontrolled burning of burning of flammable liquids like diesel can consequently cause fire in the exhaust stream (107). With the help of the present disclosure this can be prevented.

[0016] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification to a Selective Catalytic Reduction (SCR) system (100) to detect the presence of a flammable liquid in the diesel exhaust fluid tank are envisaged and form a part of this invention. The scope of this invention is limited only by the claims