Vortex tube with variable length-diameter ratio

Abstract

The invention discloses a vortex tube with a variable length-diameter ratio. The device comprises a vortex generating chamber, a cold end pipe and a hot end pipe, a nozzle is arranged on the side wall of the vortex generating chamber, and a vortex generator is arranged in the vortex generating chamber. An air chamber is arranged in the hot end pipe, an adjusting hole is formed in the top face of the air chamber, a vent hole is formed in the bottom face of the air chamber, a valve element is arranged in the air chamber, and the air chamber can axially move along the hot end pipe. A memory metal supporting cylinder is coaxially arranged in the hot end pipe, and the two ends of the supporting cylinder are connected with the air chamber and the metal sealing cover respectively. The memory metal supporting cylinder is made of nickel-titanium alloy, the nickel-titanium alloy supporting cylinder is trained through a thermal mechanical circulation method, the austenite temperature Af of the trained nickel-titanium alloy ranges from 70 DEG C to 80 DEG C, and the martensite temperature Mf ranges from 40 DEG C to 60 DEG C. The outer wall of the support cylinder is adhered with a silicone rubber heating sheet and is internally provided with a temperature sensor. On-line, continuous and variable adjustment of the length-diameter ratio of the vortex tube is achieved, the energy separation efficiency and the refrigeration performance are remarkably improved, the overall structure is compact, response is rapid, and operation is reliable.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration technology, especially the field of refrigeration device technology, and specifically relates to a vortex tube with a variable aspect ratio. Background Technology

[0002] A vortex tube is a device that achieves gas energy separation without mechanical moving parts. It can decompose compressed gas into high-temperature and low-temperature gas streams and is widely used in local refrigeration, gas drying, and heat pump systems. The performance of a traditional vortex tube is closely related to its geometry, especially the length-to-diameter ratio (L / D), which is the ratio of the effective length L of the hot-end tube (the distance from the inlet plane of the vortex tube to the end face of the regulating valve) to the inner diameter D. This is a key parameter determining energy separation efficiency and refrigeration performance. Experimental and literature studies show that different L / D values ​​correspond to different energy separation characteristics: when L / D is small (e.g., less than 10), the fluid has insufficient rotation path within the tube, resulting in inadequate energy separation; when L / D increases to 20–30, the hot-end gas stream has sufficient development length, significantly improving separation efficiency and temperature difference; when L / D further increases (above 40–50), flow friction losses increase, energy dissipation rises, and overall efficiency decreases. Therefore, most studies consider the optimal L / D value for vortex tubes to be in the range of 20–30. Traditional vortex tubes have fixed geometric parameters after manufacturing and cannot be dynamically adjusted according to operating conditions (such as inlet pressure, gas flow rate, or ambient temperature), which may deviate from the optimal L / D ratio and lead to performance degradation.

[0003] Existing regulation schemes mostly rely on external mechanical or motor drives, which suffer from drawbacks such as slow response, complex structure, high energy consumption, and insensitive control. Therefore, there is an urgent need for an intelligent structure that can adjust the length-to-diameter ratio of the vortex tube in real time and continuously to maintain optimal energy separation under varying operating conditions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a vortex tube with a variable length-to-diameter ratio, which can automatically and accurately adjust its length-to-diameter ratio according to requirements to optimize performance under different working conditions.

[0005] This invention includes a vortex generating chamber, a cold-end tube, and a hot-end tube. A nozzle is provided on the side wall of the vortex generating chamber, and a vortex generator is installed inside the chamber. The cold-end tube and the hot-end tube are respectively located at both ends of the vortex generating chamber and are connected to it. A metal cap is provided at the end of the hot-end tube, and an exhaust port is opened at the center of the metal cap.

[0006] The hot-end pipe is equipped with a regulating valve, which includes a cylindrical air chamber containing a conical valve core. An adjustment hole is located on the end face of the air chamber facing the vortex generation chamber, and the tip of the valve core corresponds to the adjustment hole. The bottom surface of the valve core is fixedly connected to the bottom surface of the air chamber via a valve stem. Multiple vent holes are evenly distributed on the same circumference on the bottom surface of the air chamber. The outer wall of the air chamber matches the shape of the inner wall of the hot-end pipe, allowing the regulating valve to move axially along the hot-end pipe.

[0007] A shape memory alloy support cylinder is coaxially disposed inside the hot-end pipe. One end of the support cylinder is fixedly connected to the bottom of the gas chamber, and the other end is fixedly connected to a metal cap. The shape memory alloy support cylinder is made of nickel-titanium alloy. The nickel-titanium alloy support cylinder is trained using a thermomechanical cycle method. After training, the austenite temperature A of the shape memory alloy support cylinder... f =70℃~80℃, martensite temperature M f =40℃~60℃. At temperatures below M... f At this time, the shape memory alloy support cylinder is in the low-temperature martensitic phase, maintaining the original length Y0 set during training. At this time, the regulating valve is closest to the vortex tube inlet, and the effective length of the hot end is the minimum value L0; when the temperature rises to M... f and A f During this period, the shape memory alloy support cylinder gradually transforms from martensite to austenite, existing in a state where both martensite and austenite coexist. Its axial length Y0 continuously shrinks to Y1 as the temperature rises, thereby pushing the regulating valve away from the vortex tube inlet and gradually increasing the effective length L0 of the hot end to L1. When the temperature rises to A... f At this point, the shape memory alloy support cylinder completely transforms into the austenitic phase, reaching the minimum length Y set during training. min At this point, the shape memory alloy support cylinder no longer shrinks further with increasing temperature, and the effective length of the hot end reaches its maximum value L. max .

[0008] The outer wall of the shape memory alloy support cylinder is covered with a silicone rubber heating element, and a temperature sensor is installed inside the shape memory alloy support cylinder. The power cord of the silicone rubber heating element and the temperature sensor are connected to the control unit.

[0009] This invention achieves continuous variation of the length-to-diameter ratio (L / D) by online adjustment of the effective length L of the hot-end tube, maintaining the L / D within an optimal range (20-30) under different operating conditions, thereby significantly improving energy separation efficiency and refrigeration performance. This invention combines the thermo-deformation characteristics of the shape memory alloy support cylinder, the rapid and precise heating capability of the silicone rubber heating element, and the closed-loop adjustment function of the intelligent control unit, enabling the vortex tube to possess the following beneficial effects: achieving online, continuous, and variable adjustment of the L / D; the control unit can dynamically adjust the temperature of the shape memory alloy support cylinder according to real-time operating conditions, ensuring the vortex tube always approaches the optimal L / D under different operating conditions; improving the overall system energy efficiency through the reuse of heat from the heating element; eliminating the need for traditional mechanical drive mechanisms, resulting in a compact structure, rapid response, and reliable operation. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0011] Figure 2 for Figure 1 A sectional view along line AA.

[0012] Figure 3 This is a schematic diagram of the shape memory alloy support cylinder at room temperature with its original length Y0.

[0013] Figure 4 This is a schematic diagram showing the shrinkage of the shape memory alloy support cylinder to Y1 under heating control.

[0014] Figure 5 This is a schematic diagram showing the shape memory alloy support cylinder in the intermediate length Y2 state under adaptive control conditions after heating is stopped. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 and Figure 2 The variable aspect ratio vortex tube includes a vortex generating chamber 1, a cold end tube 2, and a hot end tube 3. A nozzle 4 is provided on the side wall of the vortex generating chamber 1, and a vortex generator 5 is provided inside the vortex generating chamber 1. The cold end tube 2 and the hot end tube 3 are respectively provided at both ends of the vortex generating chamber 1 and are connected to the vortex generating chamber 1.

[0017] A regulating valve is installed inside the hot-end pipe 3. The regulating valve includes a cylindrical air chamber 6, inside which is a conical valve core 7. An regulating hole 8 is opened on the end face of the air chamber 6 facing the vortex generating chamber 1. The tip of the valve core 7 is positioned corresponding to the regulating hole 8. The bottom surface of the valve core 7 is fixedly connected to the bottom surface of the air chamber 6 by a valve stem 9. Multiple vent holes 10 are opened on the bottom surface of the air chamber 6, and the multiple vent holes 10 are evenly distributed on the same circumference. The outer wall of the air chamber 6 matches the shape of the inner wall of the hot-end pipe 3. The regulating valve as a whole can move along the axial direction of the hot-end pipe 3, thereby changing the effective length L of the hot-end pipe, and thus realizing the change of L / D. A metal cap 11 is provided at the end of the hot-end pipe 3, and an end exhaust hole 12 is opened at the center of the metal cap 11.

[0018] A shape memory alloy support cylinder 13 is coaxially installed inside the hot-end pipe 3. One end of the shape memory alloy support cylinder 13 is fixedly connected to the bottom of the gas chamber 6, and the other end is fixedly connected to the metal cap 11. The shape memory alloy support cylinder is made of nickel-titanium alloy. The nickel-titanium alloy support cylinder is trained by thermomechanical cycling. After training, the austenite temperature A of the nickel-titanium alloy is... f =70℃~80℃, martensite temperature M f =40℃~60℃, in this embodiment, the nickel-titanium alloy support cylinder A after training f =75℃, M f =40℃.

[0019] During operation: when the temperature is below M f At that time, the shape memory alloy support cylinder is in the low-temperature martensitic phase, maintaining the original length set during training; when the temperature rises to M... f ~A f When the temperature rises to the specified range, the shape memory alloy support cylinder is located in the martensite and austenite two-phase region and undergoes reversible axial contraction as the temperature increases, thereby driving the gas chamber 6 to move axially along the hot-end tube 3 to change the effective length L of the hot-end tube; when the temperature rises to A... f At this point, the shape memory alloy support cylinder completely transforms into the austenitic phase, and the support cylinder no longer shrinks further as the temperature increases.

[0020] A silicone rubber heating element 14 is attached to the outer wall of the shape memory alloy support cylinder 13. A temperature sensor 15 is installed inside the shape memory alloy support cylinder 13. The power cord of the silicone rubber heating element 14 and the temperature sensor 15 are connected to the control unit 16. The control unit 16 adopts a programmable logic controller (PLC) or a microcontroller control module to control the on / off state and heating power of the silicone rubber heating element 14 based on the real-time signal from the temperature sensor 15, and can implement PID or other closed-loop control algorithms. The control unit 16 may also include over-temperature protection, heating cumulative time limit, and shutdown springback logic, among other protection measures.

[0021] When high-pressure gas enters the vortex generating chamber at high speed through nozzle 4, it forms a high-angular-velocity rotating airflow within the chamber, constituting an approximate free vortex structure. The tangential velocity of the airflow increases as the radius decreases, while the static pressure decreases from the outer wall to the center. During the rotation, the gas generates intense interlayer shear. Friction and collisions between gas molecules cause some of the macroscopic rotational kinetic energy to be converted into internal energy through viscous dissipation, leading to an increase in the temperature of the outer gas layer. The outer gas layer performs work on the core gas layer through shearing, reducing the kinetic and pressure energy of the core region, and its energy is transferred to the outer region. Therefore, the temperature of the outer gas layer increases while the temperature of the core gas layer decreases significantly. Driven by radial pressure distribution, axial pressure gradient, and fluid inertia, the low-temperature core gas is discharged from the cold end pipe 2; the high-temperature outer gas, under the back pressure of the regulating valve, enters the rear section of the hot end pipe through the vent 10 and is finally discharged from the end exhaust port 12.

[0022] Implementation Method 1 (Active Control + Adaptive Mode): When the system starts, the nickel-titanium alloy support cylinder is at T0 (approximately 38°C). At this time, the shape memory alloy support cylinder is in the low-temperature martensitic phase and maintains the original length Y0 set in the training, so that the regulating valve is located at the position closest to the eddy current generating chamber, corresponding to the minimum effective length L0 of the hot end tube, with L / D ≈ 12~15. The control unit 16 energizes the heating element 14 to heat it according to the set target, causing the support cylinder 13 to rise rapidly to T1 (approximately 55°C). The shape memory alloy support cylinder 13 is in a two-phase state of austenite and martensite and undergoes axial contraction, with its length shrinking from Y0 to Y1. This pushes the gas chamber 6 to move backward along the axial direction of the hot end tube 3, increasing the effective length of the hot end from L0 to L1, and increasing the length-to-diameter ratio L / D to approximately 30. Subsequently, the power supply to the heating element is disconnected. Once the eddy current tube enters a stable operating state, the gas temperature T2 (approximately 45°C) discharged from the hot end continuously heats the support cylinder 13 through the vent 10, keeping the support cylinder within the austenite + martensite two-phase region. At this time, due to the decrease in temperature T1, the length of the support cylinder extends from Y1 to the adaptive equilibrium position Y2 (between Y0 and Y1), and the corresponding effective length of the hot end is adjusted to L2 (between L0 and L1), causing L / D to automatically drop back to approximately 25 and remain stable. This mode achieves adaptive adjustment of the effective length of the hot end without the need for continuous external heating. Figure 3 , 4 As shown in Figure 5: Figure 3 This is a schematic diagram of the shape memory alloy support cylinder at its original length Y0 under T0. At this time, the support cylinder is in the low-temperature martensitic phase, maintaining the original length set during training. The corresponding effective length of the hot end is relatively short, and the length-to-diameter ratio is relatively small. Figure 4 This is a schematic diagram showing the shrinkage of the shape memory alloy support cylinder to Y1 under active heating control. At this time, the temperature of the support cylinder rises to T1, transforms into a two-phase state of martensite and austenite, and undergoes axial shrinkage, which increases the effective length of the hot end and raises the length-to-diameter ratio to a larger value. Figure 5This is a schematic diagram showing the shape memory alloy support cylinder in its intermediate length Y2 state under adaptive control conditions after heating has stopped. Due to the de-energization of the heating element, the support cylinder elongates to Y2 (between T2 and T2) as the temperature drops. Figure 3 and Figure 4 (between the states shown), the corresponding hot end aspect ratio is also in the middle range.

[0023] Implementation Method 2 (Active Control Mode): In active control mode, the control unit 16 continuously supplies power to the heating element 14 and uses PID closed-loop regulation to stably control the temperature of the support cylinder at a target temperature (e.g., approximately 45°C). At this time, the shape memory alloy support cylinder remains in a stable state of coexistence of martensite and austenite phases, and its axial length is maintained at the target length Y. set (Between Y0 and Y1), driven by this, the position of the regulating valve remains fixed, thereby locking the effective length of the hot end at the corresponding target value L. set This maintains the length-to-diameter ratio (L / D) at approximately 25–28. This embodiment is suitable for applications requiring high temperature difference stability or control precision. The heating element 14 maintains the length Y of the support cylinder. set While maintaining a constant temperature, the generated heat can be transferred to the hot-end airflow through thermal conduction, achieving partial heat recovery while ensuring deformation control, thereby improving the overall energy efficiency of the system.

[0024] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A variable aspect ratio vortex tube, comprising a vortex generating chamber, a cold-end tube, and a hot-end tube, wherein nozzles are provided on the sidewall of the vortex generating chamber, a vortex generator is provided inside the vortex generating chamber, the cold-end tube and the hot-end tube are respectively provided at both ends of the vortex generating chamber and are connected to the vortex generating chamber; a metal cap is provided at the end of the hot-end tube, and an end exhaust hole is opened in the center of the metal cap; characterized in that: The hot-end pipe is equipped with a regulating valve, which includes a cylindrical air chamber with a conical valve core inside. An adjustment hole is opened on the end face of the air chamber facing the vortex generating chamber, and the tip of the valve core is set corresponding to the adjustment hole. The bottom surface of the valve core is fixedly connected to the bottom surface of the air chamber by a valve stem. Multiple vent holes are opened on the bottom surface of the air chamber, and the multiple vent holes are evenly distributed on the same circumference. The outer side wall of the air chamber matches the shape of the inner side wall of the hot-end pipe, and the regulating valve as a whole can move along the axial direction of the hot-end pipe. A shape memory alloy support cylinder is coaxially arranged inside the hot-end pipe. One end of the shape memory alloy support cylinder is fixedly connected to the bottom of the gas chamber, and the other end is fixedly connected to a metal cap. The shape memory alloy support cylinder is made of nickel-titanium alloy. The nickel-titanium alloy support cylinder is trained by thermomechanical cycling. After training, the austenite temperature A of the shape memory alloy support cylinder is... f =70℃~80℃, martensite temperature M f =40℃~60℃; The outer wall of the shape memory alloy support cylinder is covered with a silicone rubber heating element, and a temperature sensor is installed inside the shape memory alloy support cylinder. The power cord of the silicone rubber heating element and the temperature sensor are connected to the control unit.

2. The variable aspect ratio vortex tube as described in claim 1, characterized in that: The control unit uses a programmable logic controller or a microcontroller control module to control the on / off state and heating power of the silicone rubber heating element based on the real-time signal from the temperature sensor.

3. The variable aspect ratio vortex tube as described in claim 1, characterized in that: At temperatures below M f At this time, the shape memory alloy support cylinder is in the low-temperature martensitic phase, maintaining the original length Y0 set during training. At this time, the regulating valve is closest to the vortex tube inlet, and the effective length of the hot end is the minimum value L0; when the temperature rises to M... f and A f During this period, the shape memory alloy support cylinder gradually transforms from martensite to austenite, existing in a state where both martensite and austenite coexist. Its axial length Y0 continuously shrinks to Y1 as the temperature rises, thereby pushing the regulating valve away from the vortex tube inlet and gradually increasing the effective length L0 of the hot end to L1. When the temperature rises to A... f At the above point, the shape memory alloy support cylinder completely transforms into the austenitic phase, reaching the minimum length Y set in the training process. min At this point, the shape memory alloy support cylinder no longer shrinks further with increasing temperature, and the effective length of the hot end reaches its maximum value L. max .

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