Shape memory alloy-based cold flow ratio self-adjusting vortex tube

Abstract

We provide a vortex tube with an autonomously adjustable cold flow ratio. [Solution] The present invention provides a self-adjusting cold flow ratio vortex tube using a shape memory alloy spring. An adjustment valve and a nickel-titanium alloy spring are provided inside the hot end tube, and the valve opening is automatically adjusted by a phase transformation according to the hot end exhaust temperature, thereby achieving negative feedback control of the cold flow ratio without using an external power source and maintaining a stable cold flow ratio even under different operating conditions.

Description

Technical Field

[0001] The present invention belongs to the field of refrigeration technology, particularly relates to the field of refrigeration device technology, and specifically relates to a cold flow ratio self-regulating vortex tube based on a shape memory alloy.

Background Art

[0002] A vortex tube is an energy separation device with a simple structure and no moving parts, which can separate the gas at the compressor outlet into two streams: a cold air stream and a hot air stream.

[0003] The vortex tube utilizes the energy separation effect of a high-speed rotating airflow to output a low-temperature airflow and a high-temperature airflow at the cold end and the hot end respectively.

[0004] The cold flow ratio (i.e., the ratio of the cold air flow to the total air flow) is an important parameter that determines the cooling performance of the vortex tube, and the required cold flow ratio varies under different operating conditions.

[0005] In conventional vortex tubes, the adjustment of the cold flow ratio mostly depends on a manual adjustment method or an electronic control valve structure. The manual method cannot respond quickly to changes in operating conditions. The electronic control method needs to rely on sensors, power supplies, and electronic modules, has a complex structure, and also has limitations in the scope of application.

[0006] According to existing research, in the range where the cold flow ratio is 0 to 0.5, the relationship between the hot end outlet temperature and the valve opening degree shows that the lower the opening degree, the higher the temperature.

[0007] On the other hand, in the range where the cold flow ratio is 0.5 to 1, this relationship changes, and the hot end outlet temperature tends to be higher as the valve opening degree increases.

[0008] Based on the fact that vortex tubes have different temperature-valve opening relationships in different cold flow ratio ranges, in order to achieve full-range autonomous adjustment without requiring external energy, it is necessary to appropriately adapt shape memory alloy-driven valve mechanisms that correspond to different thermal response methods.

[0009] While the prior art document CN106016733A describes techniques for optimizing the flow path and valve structure of a vortex tube, the adjustment of the cold flow ratio relies primarily on fixed structures and external operation, and does not disclose a configuration for autonomously adjusting the cold flow ratio in response to fluctuations in the hot-end temperature during operation. In contrast, the present invention clearly differs from the aforementioned document in that it directly utilizes the hot-end exhaust temperature to actuate a shape memory alloy spring and automatically adjusts the cold flow ratio in a negative feedback manner without using an external power source or electronic control. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] China Patent Publication Publication CN106016733A [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The objective of the present invention is to overcome the drawback that conventional manual adjustment methods cannot respond to changes in operating conditions, and to provide a cold flow ratio self-adjusting vortex tube based on a shape memory alloy. [Means for solving the problem]

[0012] The present invention includes a vortex generation chamber, a cold end tube, and a hot end tube. A nozzle is provided on the side wall of the vortex generation chamber, and a vortex generator is provided inside the vortex generation chamber. The cold end tube and the hot end tube are positioned at opposite ends of the vortex generation chamber and are in communication with the vortex generation chamber.

[0013] An annular projection is provided along the circumference of the inner wall of the hot end tube, and the hot end tube is divided into a flow diversion stage and a control stage by the annular projection. The flow diversion stage is connected to the vortex generation chamber, and a metal sealing cover is fixedly provided at the end of the control stage.

[0014] The metal sealing cover has a plurality of end exhaust holes, and these plurality of end exhaust holes are evenly distributed on the same circumference.

[0015] The control stage is provided with an adjustment mechanism, which includes an adjustment valve and a shape memory alloy spring.

[0016] The adjustment valve includes a valve core, a valve rod, and a base, all arranged coaxially.

[0017] The valve core is elongated cone-shaped, and its tip extends beyond the annular projection, forming an annular airflow passage.

[0018] The valve rod is provided passing through the limiting cylinder, the limiting cylinder is arranged coaxially with the hot end tube and is fixedly connected to the inner wall of the hot end tube via a support frame.

[0019] One end of the valve rod is fixed to the center of the bottom surface of the valve core, and the other end is fixed to the center of the top surface of the base.

[0020] One end of the shape memory alloy spring is fixed to the center of the base bottom surface, and the other end is fixed to the center of the metal sealing cover, and the end exhaust hole is provided outside the area of ​​the shape memory alloy spring.

[0021] The aforementioned shape memory alloy spring is made of nickel-titanium alloy and has been trained using a thermomechanical circulation method. The austenitic transformation temperature Af of the nickel-titanium alloy after training is 70°C to 80°C, and the martensitic transformation temperature Mf is 35°C to 45°C.

[0022] In the present invention, an adjustment valve is provided inside the hot end pipe and is interlocked with a shape memory alloy spring.

[0023] When the hot end exhaust temperature changes, the shape memory alloy undergoes a controllable deformation due to the phase transformation, drives the conical valve core to adjust the opening degree of the annular passage, and realizes the automatic adjustment of the cold flow ratio.

[0024] To correspond to different cold flow ratio ranges, the following method is adopted.

[0025] (1) The heat shrinkable type shape memory alloy spring is applied in the range of cold flow ratio of 0 to 0.5. When the temperature rises, it shrinks and moves the valve core in the direction of the hot end, increasing the valve opening degree to suppress the rise of the hot end temperature.

[0026] (2) The heat extensible type shape memory alloy spring is applied in the range of cold flow ratio of 0.5 to 1. When the temperature rises, it extends and moves the valve core in the direction of the cold end, reducing the valve opening degree.

[0027] These two types of springs can be selected according to the target operating conditions, whereby the vortex tube realizes the passive automatic adjustment over the entire cold flow ratio range.

[0028] The present invention has the advantages of simple structure, no need for external energy supply, automatically forming negative feedback control based on the hot end exhaust temperature, maintaining a stable cold flow ratio under different operating conditions, fast response speed, high reliability, and long service life.

[0029] Furthermore, by pre-designing the phase transformation temperature and driving characteristics of the shape memory alloy spring, the present invention conforms its response curve to the optimal efficiency region of the vortex tube under the cold flow ratio range and different suction pressure conditions, drives the adjustment valve to dynamically fix the operating point of the system in the high-efficiency region, and realizes the autonomous optimization of the cold flow ratio and the remarkable improvement of the overall operating efficiency under variable operating conditions.

Effect of the Invention

[0030] Compared with the prior art, the present invention realizes fully automatic and power-free high-efficiency adjustment through a thermo-mechanical intelligent response mechanism based on a shape memory alloy.

[0031] This system directly converts the hot-end exhaust temperature into mechanical displacement by means of a shape memory alloy spring, drives a conical adjustment valve to change the opening degree of the air flow passage, and thus completes the autonomous closed-loop control of the cold flow ratio without the need for an external sensor and power supply.

[0032] The present invention does not require a complex electronic control unit, has high reliability and long service life, can follow changes in operating conditions in real time, and can dynamically optimize energy efficiency.

[0033] In addition, the overall structure is compact, can be directly incorporated into the hot end of an existing vortex tube, has a low retrofit cost, and has extremely high value for industrialization and popularization.

Brief Description of the Drawings

[0034] [Figure 1] It is a schematic configuration diagram showing the overall structure of the present invention. [Figure 2] It is a cross-sectional view taken along the line A-A of FIG. 1. [Figure 3] It is a schematic diagram showing the initial state of the vortex tube when the cold flow ratio is 0 < n ≤ 0.5. [Figure 4] It is a schematic diagram showing the state where the temperature of the vortex tube reaches or exceeds Mf when the cold flow ratio is 0 < n ≤ 0.5. [Figure 5] It is a schematic diagram showing the state where the temperature of the vortex tube drops below Mf when the cold flow ratio is 0 < n ≤ 0.5. [Figure 6] It is a schematic diagram showing the initial state of the vortex tube when the cold flow ratio is 0.5 < n < 1. [Figure 7] It is a schematic diagram showing the state where the temperature of the vortex tube reaches or exceeds Mf when the cold flow ratio is 0.5 < n < 1. [Figure 8]It is a schematic diagram showing a state where the temperature of the vortex tube has dropped below Mf when the cold flow ratio is 0.5 < n < 1.

Embodiments for Carrying Out the Invention

[0035] As shown in FIGS. 1 and 2, the cold flow ratio self-regulating type vortex tube based on the shape memory alloy according to the present invention includes a vortex generation chamber 1, a cold end tube 2, and a hot end tube 3.

[0036] A nozzle 4 is provided on the side wall of the vortex generation chamber 1, and a vortex generator 5 is provided in the vortex generation chamber 1.

[0037] The cold end tube 2 and the hot end tube 3 are respectively arranged at both ends of the vortex generation chamber 1 and communicate with the vortex generation chamber 1.

[0038] An annular protrusion 6 is provided along the inner wall circumference of the hot end tube 3, and the hot end tube 3 is divided into a flow splitting section and a control section by the annular protrusion 6.

[0039] The flow splitting section is connected to the vortex generation chamber 1, and a metal sealing cover 7 is fixedly provided at the end of the control section.

[0040] A plurality of end exhaust holes 8 are opened in the metal sealing cover 7, and the plurality of end exhaust holes 8 are evenly distributed on the same circumference.

[0041] An adjustment mechanism is provided in the control section, and the adjustment mechanism includes an adjustment valve and a shape memory alloy spring 15.

[0042] The adjustment valve includes a valve core 9, a valve rod 10, and a base 11 arranged coaxially.

[0043] The valve core 9 is in an oval conical shape, and its tip extends beyond the annular protrusion 6 to form an annular air flow passage 12.

[0044] The taper angle of the valve core 9 is 0.2 to 0.3, and the inner surface of the annular projection 6 is an inclined surface that fits the valve core 9.

[0045] The valve rod 10 is provided through the limiting cylinder 13, which is coaxially positioned with the hot end tube 3 and is fixedly connected to the inner wall of the hot end tube 3 via a support frame 14.

[0046] One end of the valve rod 10 is fixed to the center of the bottom surface of the valve core 9, and the other end is fixed to the center of the top surface of the base 11.

[0047] One end of the shape memory alloy spring 15 is fixed to the center of the bottom surface of the base 11, and the other end is fixed to the center of the metal sealing cover 7.

[0048] The end exhaust port 8 is located outside the range of the shape memory alloy spring 15 and is used for the discharge of hot end gas, while also ensuring that the hot airflow is in sufficient contact with the shape memory alloy spring 15.

[0049] The shape memory alloy spring 15 is made of a nickel-titanium alloy and has been subjected to a training process using a thermomechanical circulation method.

[0050] The austenitic transformation temperature Af of the nickel-titanium alloy after training is 70°C to 80°C, and the martensitic transformation temperature Mf is 35°C to 45°C. In this example, the Af of the nickel-titanium alloy spring after training is 75°C and the Mf is 40°C.

[0051] The compressed gas flows into the vortex generation chamber 1 through the nozzle 4, and the structural action of the vortex generator 5 and the vortex generation chamber 1 causes the airflow to undergo a violent swirling motion.

[0052] During the swirling process, the gas undergoes energy separation in the radial direction under the action of centrifugal force. That is, the inner airflow located near the axis center of the vortex tube loses energy during the process of moving outward, and its temperature drops significantly. On the other hand, the outer airflow located near the inner wall of the hot end tube 3 gains additional energy due to the centrifugal action, and its temperature rises.

[0053] As a result, a low-temperature cold airflow and a high-temperature hot airflow can be obtained from both ends of the vortex tube respectively.

[0054] The cold end tube 2 is responsible for outputting the low-temperature airflow, and the hot end tube 3 is responsible for outputting the high-temperature airflow.

[0055] By controlling the valve opening degree in the hot end tube 3, the flow rate distribution ratio of the cold airflow and the hot airflow can be changed, thereby changing the cold flow ratio (the ratio of the cold airflow to the total airflow), and it becomes possible to adjust the cooling or heating effect of the vortex tube.

[0056] The automatic control range in this embodiment is optimized for the range of cold flow ratio 0 < n ≤ 0.5, ensuring that the vortex tube has good energy efficiency even in the low cold flow ratio region.

[0057] In the range of cold flow ratio 0 < n ≤ 0.5, the relationship between the hot end temperature and the valve opening degree shows the characteristic that the higher the valve opening degree, the lower the hot end outlet temperature.

[0058] In this embodiment, the shape memory alloy spring is set as a "heating and shrinking type", which shrinks when the temperature rises and elongates when the temperature drops.

[0059] As shown in FIGS. 3, FIGS. 4 and FIGS. 5, when the vortex tube is installed at the condenser outlet position of the heat pump air conditioner, taking the initial temperature as T1 (35°C) (T1 < Mf), the spring length as L1, and the opening degree of the valve core 9 as the initial opening degree a.

[0060] During operation, when the hot-end gas temperature T2 rises to reach or exceed Mf (i.e., T2 usually reaches 45°C), the shape memory alloy spring 15 starts a phase transformation to become a martensite phase and contracts to length L2.

[0061] At this time, the valve rod 10 is retracted, the valve core 9 moves in the direction of the hot end, the cross-sectional area of the annular gas flow passage 12 increases, and the valve core 9 moves to the position of the second opening degree b.

[0062] As a result, the gas flow resistance in the hot-end tube 3 is reduced, the cold flow ratio of the exhaust gas flow increases, and as a result, the hot-end outlet temperature decreases.

[0063] During the temperature drop process, when the hot-end temperature drops to T3 (i.e., Mf < T3 < T2) between T2 and Mf, the shape memory alloy spring 15 enters a partial reverse transformation stage and gradually extends to length L3 (L1 > L3 > L2).

[0064] Along with this, the valve core 9 also moves in the direction of the initial position, and the passage opening degree decreases to c (b > c > a).

[0065] The decrease in the valve core opening degree causes the hot-end outlet temperature to rise slightly. The temperature rise causes the shape memory alloy spring 15 to contract slightly, and then the valve core opening degree increases slightly, causing the hot-end outlet temperature to decrease slightly again.

[0066] This is a process in which the valve core opening degree, the hot-end outlet temperature, and the length of the shape memory alloy spring dynamically reach equilibrium, and finally the shape memory alloy spring reaches an autonomous optimal position.

[0067] Through the above process, an autonomous closed-loop feedback is formed between the shape memory alloy spring and the hot-end temperature. Even when temperature fluctuations occur, the disturbance is dynamically offset by the automatic deformation of the spring, and the vortex tube system is stabilized at a new operating point, realizing a stable operating state of heating at one end and cooling at the other end.

[0068] Similarly, in the range of 0.5 < n < 1 for the cold flow ratio, the relationship between the hot end temperature and the valve opening shows an inverse trend. As shown in FIGS. 6, 7, and 8, the higher the valve opening, the higher the hot end outlet temperature.

[0069] To conform to this relationship, a "heat expansion type" shape memory alloy spring obtained by a training process, which is well-known to those skilled in the art, can be used for the adjustment within this range.

[0070] Assume that the vortex tube is installed at the condenser outlet position of the heat pump air conditioner, the initial temperature is T1 (35 °C) (T1 < Mf), the shape memory alloy spring is in the martensite phase, the spring length is L4, and the opening of the valve core 9 is the initial opening d.

[0071] During operation, when the hot end gas temperature T4 rises and reaches or exceeds Mf (that is, T4 usually reaches 45 °C), the shape memory alloy spring starts a phase transformation and extends to length L5.

[0072] At this time, the valve rod 10 is pushed out, the valve core 9 extends and moves in the cold end direction, the cross-sectional area of the annular gas flow passage 12 decreases, and the valve core 9 moves to the position of the second opening e.

[0073] As a result, the gas flow resistance in the hot end tube 3 increases, the cold flow ratio of the exhaust gas flow decreases, and as a result, the hot end temperature decreases.

[0074] During the temperature decrease process, when the hot end temperature decreases to T6 between T5 and Mf (that is, Mf < T6 < T5), the shape memory alloy spring enters a partial reverse transformation stage and gradually shortens to another length L6 (L5 > L6 > L4).

[0075] Along with this, the valve core 9 also retreats in the initial position direction, automatically returns to a relatively large opening, and the passage opening increases to f (d > f > e).

[0076] As the valve core opening increases, the hot end outlet temperature rises slightly. This slight temperature increase causes the shape memory alloy spring to stretch slightly, which in turn reduces the valve core opening again, causing the hot end outlet temperature to decrease slightly.

[0077] This is a process in which the valve core opening, hot end outlet temperature, and shape memory alloy spring length dynamically equilibrium, and the shape memory alloy spring eventually reaches its autonomous optimal position.

[0078] Through the process described above, an autonomous closed-loop feedback is formed between the shape memory alloy spring and the hot end temperature. Even if temperature fluctuations occur, the disturbance is dynamically canceled out by the automatic deformation of the spring, stabilizing the vortex tube system at a new operating point and achieving a stable operating state with heating at one end and cooling at the other.

[0079] This embodiment can satisfy the requirement for automatic adjustment in the high cooling flow ratio range.

[0080] Due to the different thermal response modes of the two types of shape memory alloys described above, the present invention allows for the selection of an appropriate spring type depending on the range of the cold flow ratio, thereby enabling the vortex tube to achieve a stable and highly efficient autonomous adjustment effect across the entire cold flow ratio range (0 to 1).

[0081] As described above, the adjustable vortex tube device using a shape memory alloy spring according to the present invention directly uses the hot end exhaust temperature to drive the deformation of the shape memory alloy spring, thereby changing the opening degree of the conical valve core 9, and thus realizing an automatic adjustment function that does not require an external power supply or sensors.

[0082] This configuration simplifies the control system, improves reliability and lifespan, and allows for rapid response to changes in operating conditions, continuously optimizing the operating performance of the vortex tubes.

[0083] Although specific embodiments of the present invention have been described above, the scope of protection of the present invention is not limited to these.

[0084] Any modification or substitution that can be easily conceived within the technical scope disclosed by an engineer familiar with this art should be included within the scope of protection of the present invention.

[0085] Therefore, the scope of protection of the present invention shall be determined by the description in the claims.

Claims

1. A vortex tube with autonomously adjustable cold flow ratio based on a shape memory alloy, It includes a vortex generation 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 generation chamber (1), and a vortex generator (5) is provided inside the vortex generation chamber (1). The cold end tube (2) and the hot end tube (3) are each provided at both ends of the vortex generation chamber (1) and are in communication with the vortex generation chamber (1). An annular projection (6) is provided along the circumference of the inner wall of the hot end tube (3), and the annular projection (6) divides the hot end tube (3) into a flow divider stage and a control stage, the flow divider stage is connected to the vortex generation chamber (1), a metal sealing cover (7) is fixedly provided at the end of the control stage, and a plurality of end exhaust holes (8) are opened in the metal sealing cover (7), and the plurality of end exhaust holes (8) are evenly distributed on the same circumference. An adjustment mechanism is provided within the control stage, and the adjustment mechanism includes an adjustment valve and a shape memory alloy spring. The adjustment valve includes a valve core (9), a valve rod (10), and a base (11) arranged coaxially. The valve core (9) is elongated cone-shaped, and its tip extends beyond the annular projection (6) to form an annular airflow passage (12). The valve rod (10) is provided passing through the limiting cylinder (13), the limiting cylinder (13) is arranged coaxially with the hot end tube (3), and is fixedly connected to the inner wall of the hot end tube (3) via a support frame (14). One end of the valve rod (10) is fixed to the center of the bottom surface of the valve core (9), and the other end is fixed to the center of the top surface of the base (11). One end of the shape memory alloy spring (15) is fixed to the center of the bottom surface of the base (11), and the other end is fixed to the center of the metal sealing cover (7), and the end exhaust hole (8) is opened outside the area of ​​the shape memory alloy spring (15). The shape memory alloy spring (15) is made of a nickel-titanium alloy and has been subjected to a training process by thermomechanical circulation. The nickel-titanium alloy is characterized in that, after training, its austenite transformation temperature Af is 70°C to 80°C, and its martensitic transformation temperature Mf is 35°C to 45°C. A vortex tube with self-regulating cold flow ratio based on shape memory alloy.

2. When the cold flow ratio of the vortex tube is 0 < n ≤ 0.5, the nickel-titanium alloy spring is trained as a heat-shrinkable type, and when the temperature exceeds the martensitic transformation temperature Mf, the nickel-titanium alloy spring shrinks. When the cold flow ratio of the vortex tube is 0.5 < n < 1, the nickel-titanium alloy spring is trained as a heat-stretching type, and when the temperature exceeds the martensitic transformation temperature Mf, the nickel-titanium alloy spring stretches. A vortex tube with self-adjusting cold flow ratio based on a shape memory alloy as described in claim 1.

3. The valve core (9) is characterized in that the taper angle is 0.2 to 0.

3. A vortex tube with self-adjusting cold flow ratio based on a shape memory alloy according to claim 1 or 2.

4. The inner surface of the annular projection (6) is characterized by being an inclined surface that fits the valve core (9). A vortex tube with self-adjusting cold flow ratio based on a shape memory alloy according to claim 1 or 2.

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