KR102597708B1 - SCR system with superhydrophobic surface treatment characteristics - Google Patents

Abstract

The present invention provides an exhaust pipe that guides the flow of exhaust gas discharged from a diesel engine; A urea solution injection, which is provided on one side of the exhaust pipe and selectively injects a urea solution; And a superhydrophobic pattern part formed at the point where the urea aqueous solution is injected in the exhaust pipe, so that the injected urea aqueous solution collides and disperses, so that the urea aqueous solution injected from the urea solution injection does not stick to the inner surface of the exhaust pipe, and is sprayed. Provides an SCR system with superhydrophobic surface treatment properties that can achieve significant improvement in ammonia production by dispersing urea water particles smaller than the urea water particle size and increasing the evaporation rate and saturation of the sprayed urea solution. do.

Description

SCR system with superhydrophobic surface treatment characteristics}

The present invention relates to a SCR system with superhydrophobic surface treatment characteristics, and more specifically, to form a superhydrophobic pattern part at the point where the urea solution is injected in the exhaust pipe of a diesel engine, so that the urea solution is sprayed from the urea solution injection. The aqueous solution does not stick to the inner surface of the exhaust pipe and disperses into urea particles smaller than the size of the sprayed urea solution, thereby increasing the evaporation rate and saturation of the sprayed urea solution, resulting in significant improvement in ammonia production. This relates to a SCR system with superhydrophobic surface treatment properties.

In general, the SCR system is an abbreviation for Selective Catalyst Reduction (SCR), which is an ammonia (NH₃) aqueous solution or urea (NH₂) called urea solution (UWS) consisting of 40% urea and 60% water. This is a device that sprays 2CO)) aqueous solution into the exhaust gas and converts it into water (H₂O) and nitrogen (N₂) through a catalytic reaction.

This reduces not only nitrogen oxides (NOx) but also carbon monoxide, which is generated in large quantities from the engine, and is known to have a numerical reduction effect of about 65-85%.

The SCR system has the advantage of improving fuel efficiency and keeping the inside of the engine clean for a long time in that it does not inject additional fuel or create accumulations through exhaust gas recirculation.

However, the urea solution easily adheres to the inner wall of the exhaust pipe, and under the influence of temperature, the solid residue of the urea solution attached to the inner wall of the exhaust pipe can easily harden due to moisture evaporation.

Therefore, in the SCR system for diesel engines, urea water evaporation and saturation are the main processes to check the quality of the SCR system.

Many researchers changed the injection pressure and injection angle of urea injection, but still did not find significant improvement. The urea solution easily solidifies when affected by temperature, which is why the urea solution treatment is effective in all diesel engines, especially mass flow and temperature. This is the main reason why it is not easy to apply to engines with high .

In addition, urea water injection injects urea solution according to the nitrogen oxide (NOx) mass flow rate of the diesel engine. The urea water particles (droplets) injected from the urea water injection directly collide with the inner wall of the exhaust pipe and are dispersed inside the exhaust pipe, but this process In this case, the urea water is not dispersed as well as theoretically, and after colliding with the inner wall of the exhaust pipe, it adheres, causing the problem that the attached elements are difficult to evaporate and become solid.

For prior art, refer to Patent Publication No. 10-2017-0016067 (2017.02.13).

The present invention forms a fine pattern by forming lattice grooves and burrs, which are molten remains, continuously and repeatedly at the point where the urea solution is sprayed in the exhaust pipe of a diesel engine, or by forming conical protrusions repeatedly and repeatedly at regular intervals, and the fine pattern is hydrophobic. By forming a superhydrophobic pattern part through annealing using ethanol, the urea solution sprayed from urea water injection does not stick to the inner surface of the exhaust pipe, but is dispersed into urea water particles of a size smaller than the size of the sprayed urea water particle size. The purpose is to provide an SCR system with superhydrophobic surface treatment characteristics that can significantly improve ammonia production by increasing the evaporation rate and saturation of the aqueous urea solution.

The SCR system with superhydrophobic surface treatment characteristics according to the present invention includes an exhaust pipe that guides the flow of exhaust gas discharged from a diesel engine; A urea solution injection provided on one side of the exhaust pipe and selectively injecting a urea solution into the inside of the exhaust pipe; And a superhydrophobic pattern portion formed at a point in the exhaust pipe where the urea aqueous solution is sprayed, allowing the sprayed urea aqueous solution to collide and disperse, wherein the micropattern of the superhydrophobic pattern portion has a depth of 25 to 100 ㎛ on the surface and a width of A lattice groove of 15 to 25 ㎛ is formed, and burrs, which are molten remains protruding to a height of 15 to 23 ㎛ around the lattice groove, are formed continuously and repeatedly to form a fine pattern, and the fine pattern is annealed using ethanol. Including those made to have hydrophobicity.

delete

In addition, the SCR system with superhydrophobic surface treatment characteristics according to the present invention includes an exhaust pipe that guides the flow of exhaust gas discharged from a diesel engine; A urea solution injection provided on one side of the exhaust pipe and selectively injecting a urea solution into the inside of the exhaust pipe; And a superhydrophobic pattern portion formed at a point in the exhaust pipe where the urea aqueous solution is sprayed, allowing the sprayed urea aqueous solution to collide and disperse, wherein the superhydrophobic pattern portion has a height of 15 to 23 ㎛ on the surface and a bottom diameter of 40 ㎛. It includes cone-shaped protrusions measuring ~80㎛ and having an upper diameter of 10-20㎛ repeatedly protruding at regular intervals to form a micropattern, and the micropattern was made hydrophobic by annealing using ethanol.

In addition, the superhydrophobic pattern part according to the present invention is preferably located in front of the urea water injection in the exhaust pipe.

In addition, the urea solution injection according to the present invention preferably achieves an injection angle of 90° based on the flow direction of the exhaust gas flowing along the exhaust pipe.

The SCR system with superhydrophobic surface treatment characteristics according to the present invention has the following effects.

At the point where the urea solution is sprayed in the exhaust pipe of a diesel engine, lattice grooves and burrs, which are molten remains, are formed continuously or cone-shaped protrusions are formed repeatedly at regular intervals to form a fine pattern, and the fine pattern is made hydrophobic. By forming a superhydrophobic pattern part through annealing using urea water injection, the urea solution sprayed from the urea water injection does not stick to the inner surface of the exhaust pipe, but is dispersed into urea water particles smaller than the size of the sprayed urea water particle size, and the sprayed urea water solution By increasing the evaporation rate and saturation, it has the effect of achieving significant improvement in ammonia production.

In addition, the evaporation rate of urea water increases, minimizing the creation of urea solid residue on the inner wall of the exhaust pipe, which has the effect of improving the durability of the SCR system.

Figure 1 is an exemplary diagram showing an SCR system with superhydrophobic surface treatment characteristics according to an embodiment of the present invention.
Figure 2 is a reference diagram showing the basic theory of superhydrophobic materials.
Figure 3 is a reference diagram showing the superhydrophobic pattern surface mechanism according to an embodiment of the present invention.
Figure 4 is an example diagram showing a state of processing a superhydrophobic pattern on a plate using a laser device.
Figure 5 is a photograph showing a plate treated with a superhydrophobic surface according to an embodiment of the present invention.
Figure 6 is a reference diagram showing the formation of a superhydrophobic pattern with microgrooves and burrs of a lattice according to an embodiment of the present invention.
Figure 7 is a reference diagram showing the formation of a superhydrophobic pattern with conical protrusions according to an embodiment of the present invention.
Figure 8 is a photograph showing urea solid residue produced on a plate without a superhydrophobic pattern.
Figure 9 is a photograph showing urea solid residue generated on a plate forming a superhydrophobic pattern according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms or words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor should appropriately define the concept of terms in order to explain his or her invention in the best way. Based on the principle of definability, it must be interpreted with meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent the entire technical idea of the present invention, so at the time of filing this application, they can be replaced by equivalent equivalents. It should be understood that variations may exist.

The present invention provides a superhydrophobic portion at the point where the urea solution is injected from the exhaust pipe of a diesel engine, so that the urea solution sprayed from the urea solution injection does not stick to the inner surface of the exhaust pipe, and the urea solution has a smaller size than the injected urea solution droplet size. This relates to an SCR system with superhydrophobic surface treatment properties that can be dispersed in a few drops and increase the evaporation rate and saturation of the urea aqueous solution to obtain significant improvement in ammonia production. Referring to the drawings, it is as follows.

The SCR system with superhydrophobic surface treatment characteristics according to an embodiment of the present invention with reference to FIG. 1 includes an exhaust pipe 100, a urea solution injection 200, and a superhydrophobic pattern portion 300. First, the exhaust pipe 100 (100) guides the flow of exhaust gas discharged from a diesel engine.

At this time, the exhaust pipe 100 is a hollow pipe like a typical exhaust pipe and is connected to the exhaust port of a diesel engine, thereby guiding the flow of exhaust gas discharged after combustion from the diesel engine to be discharged to the outside.

A urea solution injection 200 is provided on one side of the exhaust pipe 100, and the urea solution injection 200 selectively injects an aqueous urea solution in response to the flow of exhaust gas.

At this time, it is preferable that the urea solution injection 200 selectively injects the urea solution at a pressure of 3 to 5 bar in response to the consumption amount.

A superhydrophobic pattern portion 300 is formed at a point in the exhaust pipe 100 where the urea aqueous solution is injected. The superhydrophobic pattern portion 300 is formed when the urea aqueous solution injected from the urea water injection 200 collides with the exhaust pipe. Let it disperse inside (100).

At this time, the superhydrophobic pattern portion 300 is formed by continuously repeating micro-sized lattice microgrooves or cone-shaped protrusions to form a superhydrophobic micropattern on the surface.

The superhydrophobic pattern portion 300 is located in front of the urea water injection 200 or at a position where the urea aqueous solution directly hits the exhaust pipe 100, and this location optimizes the performance of the superhydrophobic pattern portion 300. Very useful.

Here, the superhydrophobic pattern portion 300 helps disperse the particles of the urea solution sprayed into the exhaust pipe 100, and converts them into urea water particles smaller than the size of the urea water solution sprayed from the urea water injection 200. dispersed.

Small particles of urea water evaporate inside the exhaust pipe 100, which maintains a high temperature, and become ammonia after being heated by hot exhaust gas from a diesel engine.

Conventionally, even if a large amount of urea water collides with the inner wall of the exhaust pipe 100, it is not dispersed and remains as droplets on the inner wall, and only moisture evaporates from the urea water droplets, leaving a solid residue on the inner wall of the exhaust pipe 100. This was created.

This has emerged as a problem that impairs the performance of the SCR system because ammonia, which reduces nitrogen oxides (NOx), cannot be produced as much.

However, the superhydrophobic pattern portion 300 is provided at the point where the urea aqueous solution according to an embodiment of the present invention is injected, so that the urea solution has a size smaller than the urea particle size injected from the urea solution injection 200. Let it disperse into particles.

At this time, the relatively small size of the urea water particles is easily affected by the internal temperature of the exhaust pipe 100, thereby increasing the evaporation rate of the urea solution inside the exhaust pipe 100, thereby increasing the saturation of the urea water solution inside the exhaust pipe. .

Therefore, applying the above-described superhydrophobic pattern part 300 to the SCR system can greatly improve the quality of the ammonia generation process and improve the performance of the SCR system.

Looking at the superhydrophobic pattern portion 300 according to an embodiment of the present invention in more detail, as follows.

과,

은 입자(물방울)를 수축시키려고, 장력

는 입자(물방울)가 표면에 퍼지도록 한다. First, Figure 2 shows the basic theory of superhydrophobic materials, and in [Equation 1] below based on Young's model equation theory, the tension

class,

To shrink the silver particles (water droplets), tension

causes particles (water droplets) to spread over the surface.

When the particles (water droplets) on the surface reach equilibrium, the angle between the solid/liquid interface and the liquid/vapor interface is called the contact angle (θ), and the superhydrophobic part can be applied to the SCR system based on Young's equation model. You can.

Figure 3 is a schematic image of the superhydrophobic surface mechanism. When the surface of a copper plate is processed with a laser beam, burrs, which are molten residues, are formed in the copper plate along with microgrooves.

The burr is copper (II) oxide (CuO) made by melting and oxidizing copper (CU). Since copper (II) oxide (CuO) is hydrophilic, the initial WDCA of the laser textured surface processed by the laser exhibits hydrophilicity.

The fully wet state of a hydrophilic material with a rough surface can be explained by [Equation 2] below, which is the Wenzel equation.

는 평평한 표면에서 물방울의 평형 접촉각이고,

은 거친 표면에서 완전히 젖은 상태의 물방울 접촉각이며, r은 기하학적 표면으로 나눈 실제 표면과 동일한 거칠기 계수이다.here,

is the equilibrium contact angle of a water droplet on a flat surface,

is the contact angle of a fully wet water droplet on a rough surface, and r is the roughness coefficient equal to the actual surface divided by the geometric surface.

On a flat surface of a hydrophilic material, the equilibrium contact angle is less than 90°.

And the roughness coefficients measured by confocal microscopy were 3.36, 1.78, and 1.53 at step sizes of 100, 300, and 500 μm, respectively.

In the initial WDCA, the roughness coefficient increased with increasing burr area, resulting in a decrease in step size.

And when the surface of the above-mentioned copper(II) oxide (CuO) is annealed at low temperature using ethanol, it becomes copper(I) oxide (Cu₂O). In this case, ethanol can accelerate the wettability transition.

Copper(I) oxide (Cu₂O) is a hydrophobic material and its equilibrium contact angle is greater than 90°.

Due to the large difference in the measured roughness coefficient of the surface manufactured in this way, the small difference in the measured WDCA cannot be explained by the Wenzel equation, and this state can be explained by the Cassie-Baxter equation [Equation 3].

는 거친 표면에서 부분적으로 젖은 상태의 물방울 접촉각, w1은 물-고체 표면의 면적 비율, w2는 물-공기 표면의 면적 비율이다.here,

is the water droplet contact angle in a partially wet state on a rough surface, w1 is the area ratio of the water-solid surface, and w2 is the area ratio of the water-air surface.

Therefore, the hydrophobic burrs in the microgroove pattern of the lattice can support the water droplets in a partially wet state and prevent contact between the water droplets and the flat surface.

For a superhydrophobic surface, a partially wet state with a lattice pattern of hydrophobic burs applied post-processing is required.

It has been reported that low-temperature annealing can accelerate this wettability transition in copper(II) oxide (CuO) films.

Additionally, it has been reported that ethanol accelerates the formation of copper(Ⅰ) oxide (Cu₂O) from copper(Ⅱ) oxide (CuO) and that higher temperatures showed faster transition.

However, long-term exposure to ethanol can change the chemical structure of copper(I) oxide (Cu₂O) to Cu.

Therefore, the post-treatment (ethanol) time is important to create an appropriate superhydrophobic surface. If the post-treatment time is too short, a superhydrophobic surface cannot be obtained, but if the post-treatment time is too long, Cu is formed from copper(Ⅰ) oxide (CuO). WDCA may decrease.

The appropriate time for low-temperature annealing using ethanol is 2 to 4 hours, which is the process parameter for UV nanosecond laser beam machining.

Figure 4 shows the state of processing a superhydrophobic pattern on a plate using a laser device, and a Q-switched Nd:YAG 355nm UV nanosecond pulse laser is used for laser beam processing.

At this time, the specifications of the laser device are as shown in [Table 1] below.

Parameter Value Power(W) 10 Pulse Frequency(Hz) 20 Pulse duration(ns) 20 Laser speed (mm/s) 100 material Aluminum 6061 Fabrication time 120 minutes

Laser devices with the above specifications are widely used in industry and are capable of forming relatively large burrs, which are pillar structures that can minimize contact while supporting water droplets.

To understand the phenomenon in the absence of additional elements, a 2 mm thick material was used as a substrate.

Figure 5 shows a superhydrophobic pattern portion 300 having a superhydrophobic surface pattern. The superhydrophobic material is aluminum 6061, the thickness is 2mm, and the step size is 100㎛.

To form the superhydrophobic pattern, a Q-switched Nd:YAG 355-nm UV nanosecond pulsed laser was used with 10w laser power and 100mm/s laser speed, and a fabrication time of 12 minutes was required.

Therefore, the superhydrophobic pattern part 300 can process a superhydrophobic pattern using a laser beam, and the lattice pattern exhibits isotropic superhydrophobicity in all directions with trapped air.

Figure 6 shows the superhydrophobic pattern part 300 in which a superhydrophobic surface is formed with a microgroove pattern of a grid. Based on a 2 mm thick square-sized plate, the microgroove size of the grid to obtain a superhydrophobic surface is as follows. It is shown in [Table 2].

Position A and B C D E Dimension 100㎛ ±23㎛ 100㎛ ±25㎛ 75㎛ ±23㎛ 100㎛ ±25㎛ 50㎛ ±23㎛ 100㎛ ±25㎛ 50㎛ ±15㎛ 50㎛ ±15㎛ 25㎛ ±15㎛ 50㎛ ±15㎛

Figure 7 shows the superhydrophobic pattern part 300 forming a superhydrophobic surface with a conical protrusion pattern. Based on a 2 mm thick square plate, the size of the conical protrusion to obtain a superhydrophobic surface is shown in [Table 3 below. ] is indicated.

Position A B C D Dimension ±23㎛ 20㎛ 100㎛ 80㎛ ±23㎛ 15㎛ 100㎛ 60㎛ ±15㎛ 15㎛ 50㎛ 60㎛ ±23㎛ 10㎛ 100㎛ 40㎛ ±15㎛ 10㎛ 50㎛ 40㎛

To confirm the performance of the superhydrophobic pattern portion 300 according to an embodiment of the present invention, an experiment was conducted as follows.

Figure 8 shows the urea solid residue on a plate without a superhydrophobic pattern. The experiment was conducted with an aluminum plate without a superhydrophobic pattern, and the plate was placed at the bottom of the urea injection 200.

The injection angle of the urea solution injection 200 is 90°, and the height between the nozzle of the urea solution injection 200 and the plate is 40 mm.

The urea solution was injected into the plate at an injection pressure of 5 bar and an injection speed of 4.824 kg/h, and other injection information is shown in [Table 4] below.

Injected liquid UWS (32.5% wt. urea) Injection duration 10/ 15/ 20 ms Height from the wall 40 mm Injection pressure 5 bar Injection angle 90° Wall temperature (temperature of the inner wall) ℃ 30/ 50/ 75/ 100/ 125/ 150/ 175/ 200 Injection rate 4.824 kg/h

In the experiment, the plate was heated with a ceramic heater to obtain changes in temperature, and in this case, low and high temperature readings were used to identify the formation of solid residues of the elements.

As a result of the experiment, it was found that solid residues were easily generated on plates without superhydrophobic patterns.

The reaction occurs because the elements are difficult to disintegrate and easily adhere when they hit the plate.

The attached element became solid after being heated by a ceramic heater. The urea solution consists of 40% urea and 60% water. When the urea solution was heated, the water evaporated and the urea stuck to the plate.

This reaction occurred at both low and high temperatures, and Figure 8(a) shows the solid residue at low temperature, and Figure 8(b) shows the solid residue at high temperature.

Figure 9 shows the urea solid residue on the plate on which the superhydrophobic pattern was formed. The experiment was conducted with an aluminum plate with a superhydrophobic pattern, and the plate was located at the bottom of the urea water injection 200.

The injection angle of the urea solution injection 200 is 90°, and the height between the nozzle of the urea solution injection 200 and the plate is 40 mm.

The urea solution was injected into the plate at an injection pressure of 5 bar and an injection rate of 4.824 kg/h.

In the experiment, the plate was heated with a ceramic heater to obtain changes in temperature, and in this case, low and high temperature readings were used to identify the formation of solid residues of the elements.

The experimental results showed that solid residue was significantly reduced compared to the plate without the superhydrophobic pattern.

This phenomenon is because the urea water is easily dispersed by the superhydrophobic pattern after hitting the plate, making it difficult to adhere to the plate. The dispersion of urea water creates smaller sized urea particles, and the particles easily evaporate and SCR ( SCR) system produces high quality ammonia.

Figure 8(a) shows the solid residue at low temperature, and Figure 8(b) shows the solid residue at high temperature.

Based on the above results, ammonia production is greatly improved by the superhydrophobic pattern part 300, and the amount of urea solid residue produced is also greatly reduced, so the performance of the SCR system is improved and can be applied to various diesel engines. .

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the attached patent claims.

100: exhaust pipe
200: element number injection
300: Superhydrophobic pattern part

Claims (5)

An exhaust pipe that guides the flow of exhaust gas discharged from a diesel engine;
A urea solution injection provided on one side of the exhaust pipe and selectively injecting a urea solution into the inside of the exhaust pipe; and
A superhydrophobic pattern portion formed at a point in the exhaust pipe where the urea aqueous solution is sprayed and allowing the injected urea aqueous solution to collide and disperse,
The fine pattern of the superhydrophobic pattern part is
Grid grooves with a depth of 25 to 100 ㎛ and a width of 15 to 25 ㎛ are formed on the surface, and burrs, which are molten remains that protrude to a height of 15 to 23 ㎛, are formed continuously and repeatedly around the lattice grooves to form a fine pattern. And,
SCR system with superhydrophobic surface treatment properties, characterized in that the micropattern was made hydrophobic by annealing using ethanol.
delete An exhaust pipe that guides the flow of exhaust gas discharged from a diesel engine;
A urea solution injection provided on one side of the exhaust pipe and selectively injecting a urea solution into the inside of the exhaust pipe; and
A superhydrophobic pattern portion formed at a point in the exhaust pipe where the urea aqueous solution is sprayed and allowing the injected urea aqueous solution to collide and disperse,
The fine pattern of the superhydrophobic pattern part is
Cone-shaped protrusions with a height of 15 to 23㎛, a bottom diameter of 40 to 80㎛, and an upper diameter of 10 to 20㎛ are formed on the surface by continuously repeating protrusions at regular intervals to form a fine pattern,
SCR system with superhydrophobic surface treatment properties, characterized in that the micropattern was made hydrophobic by annealing using ethanol.
The method of claim 1 or claim 3,
The superhydrophobic pattern part
SCR system with superhydrophobic surface treatment characteristics located in front of the urea water injection in the exhaust pipe.
According to any one of claim 1 or claim 3,
The element number injection is
SCR system with superhydrophobic surface treatment characteristics that achieves a spray angle of 90° based on the flow direction of the exhaust gas flowing along the exhaust pipe.

Images