A passive one-way drainage design method for rapid cooling of exhaust pipes

Abstract

The present invention relates to a passive one-way drainage design method for rapid cooling of an exhaust pipe, comprising an inlet section, a heat pipe, an air intake chamber, first and second tapered pipes, a mixing chamber, and an outlet section. The inlet section is connected to the first tapered pipe at one end away from the engine after-treatment system. The first tapered pipe extends deep into the air intake chamber. The first tapered pipe and the second tapered pipe are connected through the air intake chamber. The heat pipe is circumferentially distributed on the outer wall of the second tapered pipe. A plurality of air intake holes are circumferentially distributed on the air intake chamber. The end of the second tapered pipe is connected to the mixing chamber. The end of the mixing chamber is connected to the outlet section. The outlet section comprises a gradually expanding section, a transition section, and a bend section. The present invention utilizes the principle of the tapered pipe to form a low-pressure area in the mixing section, passively inhales ambient air at room temperature and mixes it with high-temperature exhaust gas. The heat pipe principle is further utilized to form a low-temperature and low-pressure area in the air intake chamber, thereby improving the drainage effect on the air. A vortex channel is provided in the air intake chamber to achieve the characteristic of one-way flow of the fluid to prevent exhaust gas from escaping.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel engine exhaust aftertreatment, and in particular to a passive one-way drainage design method for rapid temperature reduction of an exhaust pipe. Background Art

[0002] Diesel engines generate high-temperature exhaust during operation. When regenerating through the particulate filter, the exhaust temperature can reach over 600°C. When discharged into the environment, this high-temperature exhaust poses a serious threat to the surrounding environment and human health and safety. For military vehicles requiring stealth, the high-temperature exhaust from diesel-powered equipment generates high-temperature gas radiation, creating a significant infrared radiation source that is easily detected and targeted by enemy infrared sensors. Therefore, necessary measures must be taken to protect against this high-temperature exhaust.

[0003] In order to reduce the exhaust gas temperature, there are two methods: heat conduction and heat exchange. Heat conduction is the heat dissipation of high-temperature exhaust gas by conduction. By transferring heat to the surface of the exhaust pipe, the exhaust pipe then exchanges heat with the surrounding environment. This method has limited heat exchange capacity and cannot achieve rapid cooling. Heat exchange is the introduction of fresh low-temperature air to mix and exchange heat between cold and hot gases. This method usually installs a pump to introduce low-temperature air into the pipeline in a work-generating manner to achieve the cooling effect of the high-temperature exhaust gas. This method is costly and the equipment is complex, and there is a possibility that the exhaust gas will escape from the exhaust pipe to the external environment.

[0004] Therefore, how to design an exhaust tail pipe that can both quickly cool down and passively guide air in one direction is a problem that technicians in this field urgently need to solve. Summary of the Invention

[0005] In view of the problems existing in the background technology and to overcome the shortcomings of the existing technology, the present invention discloses a passive one-way drainage design method for rapid cooling of the exhaust pipe. The device can quickly cool the engine exhaust and is low in cost.

[0006] A passive one-way drainage design method for rapid cooling of an exhaust pipe comprises an inlet section, a heat pipe, an intake chamber, a first tapered pipe, a second tapered pipe, a mixing chamber, an outlet section, and a handrail. The inlet section is a circular tube structure, and the end of the inlet section away from the engine after-treatment system is connected to the first tapered pipe, the first tapered pipe extends into the intake chamber, and the first tapered pipe and the second tapered pipe are connected through the intake chamber. The heat pipe is distributed circumferentially on the outer wall of the second tapered pipe, and a plurality of intake holes are distributed circumferentially on the intake chamber. The end of the second tapered pipe is connected to the mixing chamber, and the end of the mixing chamber is connected to the outlet section. The outlet section comprises a gradually expanding section, a transition section, and a bend section. The starting end of the gradually expanding section is connected to the mixing chamber, the transition section and the bend section have the same diameter, and the opening at the end of the bend section is parallel to the ground.

[0007] Design of the length of the tapered section;

[0008] The tapering angle of the tapered section is known and is α, and the length is L. The tapering angle of the tapered section is kept unchanged, and the length L is determined according to the size of ΔP.

[0009] ΔP is calculated as follows:

[0010] According to Bernoulli's equation,

[0011]

[0012]

[0013] Where P1 is the pressure of the high-temperature exhaust gas at point A at the inlet section;

[0014] θ1 is the velocity of the high-temperature exhaust gas at point A on the inlet section;

[0015] h1 is the height of point A of the high-temperature exhaust gas at the inlet section;

[0016] p2 is the pressure of the high-temperature exhaust gas at point B at the entrance of the mixing section;

[0017] θ2 is the velocity of the high-temperature exhaust gas at point B at the entrance of the mixing section;

[0018] h2 is the height of point B of the high-temperature exhaust gas at the inlet of the mixing section;

[0019] g is the acceleration due to gravity;

[0020] ρ is the density of high-temperature exhaust gas;

[0021] ΔP is the pressure drop of the exhaust gas from the inlet section to the inlet section of the mixing section.

[0022] Knowing the sizes of θ1, θ2 and ρ, the size of ΔP can be obtained. If the size of P1 is also known, the size of P2, that is, the pressure of the high-temperature exhaust gas at point B at the entrance of the mixing section, can be determined. If the air is to be diverted to the mixing section, it is necessary to ensure that p2 is less than the pressure of the surrounding air P0. Because the tapering angle α is fixed, the only way to ensure that P2 is less than P0 is to adjust the size of L. Therefore, the length L of the tapering section is determined.

[0023] The heat pipes are distributed along the circumference of the outer wall of the second tapered tube, with adjacent heat pipes spaced 45 degrees apart. The hot ends of the heat pipes are close to the air intake cavity, while the cold ends are away from the air intake cavity, thereby reducing the temperature in the air intake cavity and forming a low-temperature area.

[0024] The suction chamber is provided with 6 vortex channels, 3 on the left and 3 on the right, and the vortex channels are alternately located on the inner wall of the suction chamber. The vortex channel on the left side of the chamber is higher than the vortex channel on the right side, so that the fluid can flow in one direction.

[0025] The principle of the present invention is:

[0026] like Figure 4 The present invention utilizes the principle of a reducer. When the high-speed exhaust gas flows through the reducer and enters the mixing section, a low-pressure area is formed in the mixing section. The ambient temperature air can be sucked in and mixed with the high-temperature exhaust gas under passive conditions. Figure 5 As shown, the heat pipe on the tapered tube is used to form a low-temperature area in the intake cavity, and then a low-pressure area. The high-temperature and high-pressure gas spontaneously flows to the low-temperature and low-pressure area, thereby improving the drainage effect on the air.

[0027] like Figure 6 The present invention utilizes the vortex channel in the air intake chamber. When the outside air passes through the vortex channel in the forward direction, it is equivalent to a pressure expansion structure, and the air pressure becomes increasingly greater. When the internal exhaust gas passes through in the reverse direction, most of the airflow flows into the vortex channel, and a small part of the airflow continues to move forward. The forward exhaust gas is blocked by the vortex channel, hindering the forward movement of the rear airflow.

[0028] The greater the obstruction to the forward airflow, the slower it is, until it stops. This ensures the intake of external air while preventing exhaust gas from escaping, achieving the effect of one-way flow of the fluid.

[0029] The beneficial effects achieved by the present invention are:

[0030] (1) Under passive conditions, by designing the tail pipe structure and controlling the temperature of the internal fluid, a low pressure can be achieved in some areas inside the tail pipe, thereby achieving the function of draining the air without an external power source.

[0031] (2) It can realize the unidirectional flow of fluid. Through the vortex channel design on the inner wall of the intake chamber, the flow direction of the exhaust gas entering the intake chamber is changed, thereby ensuring that the air enters the tail pipe and preventing the exhaust gas from escaping.

[0032] (3) The present invention has a simple structure, occupies a small space, and can be installed in the space outside the vehicle without destroying the original space distribution of the original vehicle.

[0033] (4) The present invention is equipped with a handrail, which greatly facilitates the workers to install and disassemble the exhaust tail pipe of the present invention.

[0034] (5) The exhaust tail pipe of the present invention is a cavity, which can further reduce exhaust noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the cooling exhaust pipe structure of the present invention.

[0036] Figure 2 Schematic diagram of the cross-sectional structure of the cooling exhaust pipe of the present invention.

[0037] Figure 3 The fluid flow diagram in the cooling exhaust pipe of the present invention

[0038] Figure 4 Diagram of the working principle of the reducer of the present invention.

[0039] Figure 5 Schematic diagram of the working principle of the heat pipe of the present invention.

[0040] Figure 6 Schematic diagram of gas flow in the vortex channel of the present invention.

[0041] In the figure, 1-inlet section, 2-first reducer, 3-intake chamber, 4-intake hole, 5-second reducer, 6-mixing chamber, 7-gradually expanding section, 8-transition section, 9-bend section, 10-handrail, 11-heat pipe, 12-vortex channel. DETAILED DESCRIPTION

[0042] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, manufacturing, devices, components and / or combinations thereof.

[0044] like Figure 1-2 The schematic diagram of the cooling exhaust tail pipe structure shown in the figure shows that the inlet section 1 is a circular tube structure, and the end of the inlet section away from the engine after-treatment system is connected to the first reducer 2, and the heat pipe 11 is a circular tube structure, which is distributed along the circumference on the outer wall of the second reducer, and the first reducer 2 extends into the interior of the intake cavity, and the first reducer 2 is connected to the second reducer 5 through the intake cavity 3. A plurality of intake holes 4 are distributed along the circumferential direction on the intake cavity 3, and a plurality of vortex channels 12 are provided in the intake cavity, and the vortex channels are alternately located on the inner wall of the intake cavity. The end of the second reducer is connected to the mixing chamber 6, and the end of the mixing chamber is connected to the outlet section, and the outlet section includes a gradually expanding section 7, a transition section 8 and a bend section 9. The starting end of the gradually expanding section is connected to the mixing chamber, the transition section and the bend section have the same diameter, and the end opening of the bend section 9 is parallel to the ground.

[0045] like Figure 3-4-5-6, during actual vehicle installation, one end of the inlet section is fixed to the engine after-treatment muffler with a clamp, and the high-temperature exhaust gas flows into the first tapered pipe through the inlet section and is injected into the mixing chamber after acceleration, forming a low-pressure area in the intake chamber. The fresh air from the outside can be sucked into the mixing chamber through the intake hole to mix with the high-temperature exhaust gas. The heat pipe on the outer wall of the second tapered pipe can further reduce the temperature in the intake chamber. The hot end absorbs the heat of the exhaust gas in the cavity, and the cold end releases heat to the surrounding environment, so that the intake chamber forms a low-temperature area, and further forms a low-pressure area. The high-temperature and high-pressure gas spontaneously flows to the low-temperature and low-pressure area, thereby improving the drainage effect on the air. The vortex channel set on the inner wall of the intake chamber allows most of the exhaust gas entering the intake chamber to flow into the vortex channel, and a small part of the airflow continues to move forward. The forward airflow encounters the vortex channel and is blocked and rebounded, hindering the forward movement of the rear airflow. The further the airflow moves forward, the greater the resistance and the slower the speed, until it stops completely, ensuring the smooth inflow of air and preventing the escape of exhaust gas. Fresh air acts as a low-temperature medium to exchange heat with the high-temperature exhaust gas in the mixing section, and finally the cooled exhaust gas is discharged through the outlet section.

Claims

1. A passive one-way drainage design method for rapid cooling of exhaust pipes, characterized in that: It includes an inlet section, a heat pipe, a suction chamber, a first tapered pipe, a second tapered pipe, a mixing chamber, and an outlet section. The inlet section is of a circular pipe structure. One end of the inlet section away from the engine aftertreatment system is connected to the first tapered pipe. The first tapered pipe extends into the interior of the suction chamber. The first tapered pipe and the second tapered pipe are connected through the suction chamber. The heat pipes are circumferentially distributed on the outer wall of the second tapered pipe. Multiple suction holes are distributed in the circumferential direction on the suction chamber. The end of the second tapered pipe is connected to the mixing chamber. The end of the mixing chamber is connected to the outlet section. The outlet section includes a gradually expanding section, a transition section, and a bent pipe section. The beginning end of the gradually expanding section is connected to the mixing chamber. The diameters of the transition section and the bent pipe section are the same. The opening at the end of the bent pipe section is parallel to the ground. Design of the length of the tapered section; If the taper angle of the tapered section is known and is α, and the length is L, while keeping the taper angle of the tapered section unchanged, determine the length L according to the magnitude of ΔP; The calculation method of ΔP is as follows: According to Bernoulli's equation, In the formula, P1 is the pressure of the high-temperature exhaust gas at point A at the inlet section of the inlet section; θ1 is the velocity of the high-temperature exhaust gas at point A at the inlet section of the inlet section; h1 is the height of the high-temperature exhaust gas at point A at the inlet section of the inlet section; P2 is the pressure of the high-temperature exhaust gas at point B at the inlet of the mixing section; θ2 is the velocity of the high-temperature exhaust gas at point B at the inlet of the mixing section; h2 is the height of the high-temperature exhaust gas at point B at the inlet of the mixing section; g is the acceleration due to gravity; ρ is the density of the high-temperature exhaust gas; ΔP is the pressure drop of the exhaust gas from the inlet section of the inlet section to the inlet section of the mixing section; Given the magnitudes of θ1, θ2, and ρ, the magnitude of ΔP can be obtained, and the magnitude of P1 is also known. Thus, determine P2, that is, the pressure magnitude of the high-temperature exhaust gas at point B at the inlet of the mixing section. If you want to divert air to the mixing section, it is necessary to ensure that P2 < the pressure P0 of the surrounding ambient air. Also, because the taper angle α is fixed and unchanged, so only by adjusting the magnitude of L to ensure that P2 < P0, thus determine the length L of the tapered section.

2. The passive one-way drainage design method for rapid exhaust pipe cooling according to claim 1, characterized in that: The heat pipes are circumferentially distributed on the outer wall of the second tapered pipe. Each adjacent heat pipe is separated by 45°, and the hot end of the heat pipe is close to the suction chamber, and the cold end is far from the suction chamber.

3. The passive one-way drainage design method for rapid exhaust pipe cooling according to claim 1 is characterized in that: There are 6 eddy current channels in the suction chamber, 3 on the left and 3 on the right. The eddy current channels are alternately located on the inner wall of the suction chamber, and the eddy current channels on the left side in the chamber are higher than those on the right side.

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