Combined throttling device and ammonia water absorption type refrigerating system

Abstract

The utility model discloses a combined throttling device and ammonia water absorption refrigeration system, wherein the combined throttling device comprises a stepping motor, a needle valve, a controller and a limit switch, the needle valve is used as a throttling element, and the stepping motor comprises an output shaft used for outputting linear displacement; the output shaft is connected with a valve needle of the needle valve and converts output displacement into linear displacement of the valve needle, the controller is used for controlling the displacement of the output shaft so as to adjust the opening degree of the needle valve, the limiting switch is connected with the controller, and when the needle valve reaches the minimum opening degree and / or the maximum opening degree, the limiting switch is triggered to send an electric signal to the controller. According to the combined throttling device, the valve needle of the needle valve is driven to axially move through accurate displacement output of the stepping motor, accurate adjustment of the sectional area of a fluid channel can be achieved, and therefore the high-accuracy control requirement of a system for refrigerant flow is met.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of ammonia water absorption refrigeration system, concretely relates to a combined throttling device and ammonia water absorption refrigeration system with same. BACKGROUND

[0002] The ammonia water absorption refrigeration system is a high-efficiency refrigeration device based on the principle of absorption cycle, and the core thereof realizes a refrigeration effect through a phase change process of an ammonia water working medium pair.The system is composed of four core components, namely, an absorber, a generator, a condenser and an evaporator.The high-pressure liquid ammonia output by the condenser is depressurized through a throttling device and then absorbs heat in the evaporator to complete a phase change and a refrigeration cycle.In addition, the throttling device in the system plays a role in controlling superheat, and is crucial to maintaining stable operation of the refrigeration cycle. SUMMARY

[0003] At present, electronic expansion valves are widely used in refrigeration systems due to their excellent throttling and superheat control performance.However, the electronic expansion valves commonly seen on the market are mostly made of copper, and ammonia and copper can react chemically, so they cannot be directly applied to ammonia water absorption systems.In addition, the high cost characteristics of such valve bodies and the response lag problem under the PWM control mode seriously restrict their practical value in ammonia refrigeration systems.Although the traditional needle valve can realize micron-level flow regulation by means of a conical valve plug structure, the manual operation mode cannot meet the real-time regulation and control requirements of the system.Therefore, it is of great practical significance to develop a throttling device suitable for ammonia water absorption refrigeration systems, which is low in cost, short in regulation period and high in regulation accuracy.

[0004] To solve the above problems, the purpose of the utility model is to provide a combined throttling device for an ammonia water absorption refrigeration system.The combined throttling device proposed in the utility model embodiment integrates the rapid regulation capability of a stepper motor and the precise flow regulation characteristics of a needle valve to realize rapid and accurate regulation of the flow passage area of the throttling valve.

[0005] The utility model also provides an ammonia water absorption refrigeration system comprising the combined throttling device.

[0006] The combined throttling device for an ammonia water absorption refrigeration system according to the utility model embodiment comprises a stepper motor, a needle valve, a controller and a limit switch, the needle valve is used as a throttling element, the stepper motor comprises an output shaft for outputting linear displacement, the output shaft is connected with a valve needle of the needle valve to convert the output linear displacement into linear displacement of the valve needle, the controller is used for controlling the linear displacement of the output shaft to regulate the opening degree of the needle valve, and the limit switch is connected with the controller, and when the needle valve reaches the minimum opening degree and / or the maximum opening degree, the limit switch is triggered to send an electric signal to the controller.

[0007] Optionally, the limit switch includes a first limit switch and a second limit switch, wherein the first limit switch is installed at the mechanical mounting position corresponding to the minimum opening position of the needle valve, and the second limit switch is installed at the mechanical mounting position corresponding to the maximum opening position of the needle valve.

[0008] Optionally, it also includes a connector that connects the output shaft and the valve needle, wherein the linear displacement of the output shaft is transmitted to the valve needle through the connector.

[0009] Optionally, the connector is provided with a first groove and a second groove located at both ends, the output shaft of the stepper motor is fixed in the first groove, and the valve needle of the needle valve is fixed in the second groove.

[0010] Optionally, the connector has two threaded holes on its side for fixing the output shaft and the valve needle with screws, respectively.

[0011] Optionally, the system also includes a frame on which the stepper motor, the needle valve, and the limit switch are all mounted.

[0012] Another embodiment of this utility model provides an ammonia absorption refrigeration system, comprising: an evaporator, an absorber, a generator, a condenser, and a combined throttling device, wherein the combined throttling device is any of the aforementioned combined throttling devices, wherein the evaporator is connected to the absorber, the absorber is connected to the generator, the generator is connected to the condenser, the condenser is connected to the evaporator, and the needle valve of the combined throttling device is connected between the condenser and the evaporator.

[0013] Optionally, it also includes an ammonia pump connected between the absorber and the generator.

[0014] Optionally, the system further includes a heat exchanger, wherein the cold-side inlet of the heat exchanger is connected to the absorber, the cold-side outlet of the heat exchanger is connected to the generator, the hot-side inlet of the heat exchanger is connected to the generator, and the hot-side outlet of the heat exchanger is connected to the absorber.

[0015] Optionally, it also includes a subcooler, the cold-side inlet of which is connected to the evaporator, the cold-side outlet of which is connected to the absorber, the hot-side inlet of which is connected to the condenser, and the hot-side outlet of which is connected to the needle valve.

[0016] The combined throttling device provided in this embodiment of the invention uses a stepper motor to precisely move the needle valve axially, thereby achieving precise adjustment of the fluid channel cross-sectional area and meeting the system's high-precision control requirements for refrigerant flow. Simultaneously, the rapid response of the stepper motor ensures that the system can adjust the needle valve opening promptly based on the superheat deviation signal, effectively avoiding system instability caused by the lag in traditional regulating devices. Furthermore, the needle valve is typically made of ammonia-resistant material, solving the incompatibility problem between traditional electronic expansion valves and ammonia refrigerant, significantly improving the device's applicability and service life. The limit switch further enhances system safety; when the valve needle moves to its minimum or maximum opening, the limit switch triggers a signal and feeds it back to the controller, promptly stopping the stepper motor and preventing mechanical overload or valve needle jamming. The combined throttling device provided in this embodiment of the invention has a simple and reliable overall structure, low manufacturing cost, and is suitable for various scenarios such as industrial waste cooling recovery and cold chain logistics, showing broad application prospects. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the combined throttling device according to an embodiment of the present invention.

[0018] Figure 2 This is a top view of the connector according to an embodiment of the present utility model.

[0019] Figure 3 This is a side view of the connector according to an embodiment of the present utility model.

[0020] Figure 4 This is a connection diagram of the ammonia absorption refrigeration system according to an embodiment of the present invention.

[0021] Figure label:

[0022] Combined throttling device 100

[0023] Stepper motor 1, output shaft 11

[0024] Needle valve 2, needle valve body 21, valve needle 22

[0025] Controller 3

[0026] Limit switch 4, first limit switch 41, second limit switch 42

[0027] Connector 5, First groove 51, Second groove 52

[0028] Framework 6

[0029] Ammonia absorption refrigeration system 200, evaporator 210, subcooler 220, absorber 230, ammonia pump 240, heat exchanger 250, generator 260, condenser 270, liquid receiver 280. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] The following reference Figures 1-4 This invention describes a combined throttling device 100 and an ammonia absorption refrigeration system 200 having such a combined throttling device 100.

[0032] like Figure 1 As shown, the combined throttling device 100 includes a stepper motor 1, a needle valve 2, a controller 3, and a limit switch 4.

[0033] Stepper motor 1 serves as the drive unit and includes an output shaft 11 that outputs linear displacement. Needle valve 2 is used as a throttling element and includes a needle valve body 21 and a valve needle 22. The output shaft 11 of stepper motor 1 is connected to the valve needle 21 of needle valve 2 and converts the output linear displacement into the linear displacement of valve needle 21.

[0034] The controller 3 is used to control the displacement of the output shaft 11 to adjust the opening of the needle valve 2. The limit switch 4 is connected to the controller 3. When the needle valve 2 reaches the minimum opening and / or the maximum opening, the limit switch 4 is triggered to send an electrical signal to the controller 3.

[0035] When the combined throttling device 100 is applied to an ammonia absorption refrigeration system, its working principle is as follows: The controller 3 receives a superheat deviation signal from the system and calculates the required number of pulses according to a preset algorithm, thereby controlling the stepper motor 1 to operate. After receiving the control signal, the output shaft 11 of the stepper motor 1 outputs a precise linear displacement. The output shaft 11 of the stepper motor 1 drives the valve needle 22 of the needle valve 2 to move axially through a mechanical connection, thereby adjusting the cross-sectional area of ​​the fluid channel of the needle valve 2 and achieving precise control of the opening degree of the needle valve 2. When the valve needle 22 moves to the minimum or maximum opening position, the limit switch 4 is triggered and sends an electrical signal to the controller 3. After receiving the signal, the controller 3 immediately stops the stepper motor 1 to prevent the valve needle 22 from moving beyond the set range and ensure the safe operation of the device.

[0036] The combined throttling device provided in this embodiment of the invention uses a stepper motor to precisely move the needle of a needle valve axially, thereby achieving precise adjustment of the cross-sectional area of ​​the fluid channel and meeting the system's high-precision control requirements for refrigerant flow. Simultaneously, the rapid response of the stepper motor ensures that the system can adjust the needle valve opening promptly based on the superheat deviation signal, effectively avoiding system instability caused by the lag in traditional regulating devices. Furthermore, the needle valve is made of ammonia-resistant material, solving the incompatibility problem between traditional electronic expansion valves and ammonia refrigerant, significantly improving the device's applicability and service life. The limit switch further enhances system safety; when the needle moves to its minimum or maximum opening, the limit switch triggers a signal and feeds it back to the controller, promptly stopping the stepper motor and preventing mechanical overload or damage to the needle valve. The combined throttling device provided in this embodiment of the invention has a simple and reliable overall structure, low manufacturing cost, and is suitable for various scenarios such as industrial waste cooling recovery and cold chain logistics, showing broad application prospects.

[0037] As described above, the limit switch 4 is triggered when the valve needle 22 moves to the minimum or maximum opening position, and its function is to provide a safety protection mechanism for the combined throttling device 100. In some embodiments, the limit switch 4 includes two independent switches: a first limit switch 41 and a second limit switch 42. The first limit switch 41 is installed at the mechanical mounting position corresponding to the minimum opening position of the needle valve 2, and the second limit switch 42 is installed at the mechanical mounting position corresponding to the maximum opening position of the needle valve 2.

[0038] Both the first limit switch 41 and the second limit switch 42 are connected to the controller 3 via signal. When the valve needle 22 moves to the fully closed state, the output shaft 11 of the stepper motor 1 or the mechanical component connected to it touches the first limit switch 41, triggering it to send an electrical signal to the controller 3. When the valve needle 22 moves to the fully open state, the output shaft 11 of the stepper motor 1 or the mechanical component connected to it touches the second limit switch 42, triggering it to send an electrical signal to the controller 3.

[0039] When any limit switch is triggered, the controller 3 immediately receives an electrical signal and takes corresponding measures, such as cutting off the power to the stepper motor 1 or executing a reverse drive command, thereby preventing the valve needle 22 from exceeding the preset mechanical stroke range and avoiding mechanical jamming or component damage due to excessive movement. This dual limit design not only improves the safety of the device but also ensures the stability and reliability of the needle valve 2 during the adjustment process. In addition, the installation position of the limit switch 4 is precisely calibrated to ensure that its triggering action strictly corresponds to the actual stroke of the valve needle 22, further improving the control accuracy. Through this design, the combined throttling device 100 can achieve high-precision and high-reliability flow regulation in the ammonia absorption refrigeration system 200, while effectively extending the service life of the device and reducing maintenance costs.

[0040] In some embodiments, the stepper motor 1 includes a stator, a rotor, a shaft, and a linear displacement assembly (not shown in the figure). The stator houses the rotor, and the rotor is connected to the shaft. When the stator is energized, it generates a rotating magnetic field to drive the rotor to rotate, thereby causing the shaft to rotate. The rotation of the shaft causes the output shaft 11 to generate linear displacement along its axial direction via the linear displacement assembly. The controller 3 is used to control the supply of power to the stepper motor 1 and to send pulse signals to the stepper motor 1. The stepper motor 1 converts the pulse signals into linear displacement of the output shaft 11.

[0041] Specifically, the stator, as the fixed part of the stepper motor 1, has windings inside and generates a rotating magnetic field when energized. The rotor, the moving part of the stepper motor 1, is usually made of permanent magnet material, located inside the stator, and rotates in response to the rotating magnetic field generated by the stator. The rotor is directly connected to the shaft, and the shaft rotates synchronously when the rotor rotates. To achieve the conversion of rotary motion into linear displacement, the stepper motor 1 is also equipped with a linear displacement assembly, which can be a ball screw mechanism or a worm gear mechanism. When the shaft rotates, the linear displacement assembly converts the rotary motion of the shaft into axial linear displacement of the output shaft 11, thereby driving the valve needle 22 of the needle valve 2 connected to the output shaft 11 to move precisely axially.

[0042] It is understood that the stator, rotor, shaft and linear displacement component of the stepper motor 1 can adopt the structure known in the art. This utility model does not elaborate on the specific operating principle of the stepper motor 1 and the motion conversion process of the linear displacement component.

[0043] The controller 3 receives command signals (e.g., superheat deviation values) from an external system (such as the control unit of an ammonia absorption refrigeration system) and calculates the required number of pulses according to a preset control algorithm. These pulse signals are transmitted to the stepper motor 1, which converts each pulse signal into a fixed angular displacement (e.g., 1.8° rotation angle per pulse). The angular displacement is then converted into axial linear displacement of the output shaft 11 via a built-in linear displacement component (e.g., a ball screw or worm gear mechanism). For example, for each pulse signal received, the output shaft 11 may move 0.01 mm axially, thereby driving the valve needle 22 of the needle valve 2 connected to the output shaft 11 to move precisely axially. The controller 3 can dynamically adjust the output frequency and number of pulse signals based on the signal from the limit switch 4 or the superheat value fed back by the system, thereby achieving precise control of the opening degree of the needle valve 2.

[0044] This design enables the stepper motor 1 to convert electrical pulse signals into high-precision mechanical displacement, and also allows for rapid response and dynamic adjustment during system operation, significantly improving the flow control performance of the combined throttling device 100 in the ammonia absorption refrigeration system. Simultaneously, the controller's intelligent management functions reduce system energy consumption and maintenance requirements, extend the device's service life, and provide a reliable guarantee for the efficient and stable operation of the ammonia absorption refrigeration system.

[0045] In some embodiments, the needle valve 2 includes a needle valve body 21 and a needle 22. The needle valve body 21 defines a fluid passage, and the needle 22 is movably disposed relative to the needle valve body 21. The tip of the needle 22 is designed as a tapered or needle-shaped structure to match the fluid passage, enabling a tight fit with the passage of the needle valve body 21. The needle 22 is mechanically connected to the output shaft 11 of a stepper motor 1 and is axially movable under the drive of the stepper motor 1. The movement of the needle 22 relative to the needle valve body 21 adjusts the opening degree of the needle valve 2.

[0046] When the tip of the valve needle 22 presses against the needle valve body 21, the fluid passage is completely cut off, and the needle valve 2 is in the closed state. When the valve needle 22 moves in the opposite direction, the cross-sectional area of ​​the fluid passage gradually increases, and the opening of the needle valve 2 also increases accordingly, thereby achieving continuous flow regulation. This design allows the needle valve 2 to achieve precise control of fluid flow through the minute displacement of the valve needle 22. For example, for every 0.01 mm movement of the valve needle 22, the cross-sectional area of ​​the fluid passage may increase or decrease by a certain proportion, thereby achieving fine-tuning of the flow rate.

[0047] Preferably, the needle valve body 21 and the valve needle 22 are made of corrosion-resistant materials (such as 316L stainless steel) to adapt to the corrosive environment of ammonia working fluid in the ammonia absorption refrigeration system, ensuring the reliability and durability of the device during long-term operation. Furthermore, preferably, the fit between the valve needle 22 and the needle valve body 21 is strictly calibrated to ensure a complete seal when closed, preventing fluid leakage.

[0048] Furthermore, the step angle of the stepper motor 1 (e.g., a rotation angle of 1.8° per pulse) is in a fixed proportional relationship with the linear displacement of the output shaft 11 (e.g., an axial movement of 0.01mm per pulse). Since the displacement of the valve needle 22 is directly related to the change in the cross-sectional area of ​​the fluid channel, the flow coefficient of the needle valve 2 is linearly related to the step angle of the stepper motor 1 to ensure smooth flow regulation.

[0049] For example, each time stepper motor 1 receives a pulse signal, valve needle 22 moves a certain distance, the cross-sectional area of ​​the fluid channel changes accordingly, and the flow coefficient is adjusted proportionally. This linear relationship allows controller 3 to achieve high-precision adjustment of the opening of needle valve 2 by precisely controlling the number of pulses, thereby meeting the stringent flow control requirements of the ammonia absorption refrigeration system. Through this structural design, needle valve 2 not only achieves high-precision flow control but also features fast response and long lifespan, significantly improving the performance of the combined throttling device 100.

[0050] In some embodiments, such as Figure 1 As shown, the combined throttling device 100 also includes a connector 5 and a frame 6. The connector 5 connects the output shaft 11 to the valve needle 22. The linear displacement of the output shaft 11 is transmitted to the valve needle 22 through the connector 5, thereby adjusting the opening of the needle valve 2. The frame 6 serves as the support structure for the entire device. The stepper motor 1, the needle valve 2, and the limit switch 4 are all mounted on the frame 6, forming a compact and stable whole.

[0051] Optionally, the connector 5 is a metal connector, preferably made of a corrosion-resistant material with sufficient mechanical strength to prevent corrosion due to ammonia leakage or deformation of the internal groove due to long-term use, which would affect the control effect.

[0052] Optionally, such as Figure 1 As shown, the connector 5 has a first groove 51 and a second groove 52, which are respectively located at both ends of the connector 5. The output shaft 11 of the stepper motor 1 extends into the first groove 51, and the valve needle 22 of the needle valve 2 extends into the second groove 52. The connector 5 has a side opening for screwing in a screw to fix the output shaft 11 and the valve needle 22.

[0053] Optionally, frame 6 is an aluminum profile frame. The aluminum profile frame measures 600mm in length and 200mm in width. The aluminum profile is of the European standard 2020 series and is connected via corner brackets, which are also European standard 2020 corner brackets. Stepper motor 1 is fixed to the upper part of the aluminum profile frame. Two end-face connecting plates are installed on the upper part of the aluminum profile. The end-face connecting plates are 57×25mm in size, with a 6.3mm diameter opening in the middle and 5mm diameter openings on both sides. When fixing stepper motor 1, the two end-face connecting plates are connected in the middle to the upper part of the aluminum profile frame. Four openings with a 57mm gap in the middle are used to connect the four corners of stepper motor 1 to the end-face connecting plates, using M5 threads and matching nuts.

[0054] This utility model embodiment also provides an ammonia absorption refrigeration system 200. For example... Figure 2As shown, the ammonia absorption refrigeration system 200 includes: an evaporator 210, a subcooler 220, an absorber 230, an ammonia pump 240, a heat exchanger 250, a generator 260, a condenser 270, and a combined throttling device. The combined throttling device is the combined throttling device 100 provided in this embodiment of the invention.

[0055] The outlet of evaporator 210 is connected to absorber 230 via the cold side of cooler 220. Ammonia pump 240 is connected between the outlet of absorber 230 and heat exchanger 250. The outlet of heat exchanger 250 is connected to generator 260. The outlet of generator 260 is connected to condenser 270. The outlet of condenser 270 is connected to the hot side of subcooler 220. The needle valve 2 of combined throttling device 100 is connected between subcooler 220 and evaporator 210.

[0056] Specifically, the ammonia solution is heated in generator 260, causing ammonia gas to escape from the solution. The remaining dilute ammonia solution flows through a pipe to absorber 230, and during its flow to absorber 230, it passes through the hot side of heat exchanger 250 to recover heat and improve energy efficiency. The ammonia gas exiting generator 260 enters condenser 270, where it is cooled and liquefied into liquid ammonia. The liquid ammonia enters receiver 280. The outlet of receiver 280 is connected to the hot side of subcooler 220, which is used to further cool the liquid ammonia to improve refrigeration efficiency. The subcooled liquid ammonia discharged from the hot side outlet of subcooler 220 passes through needle valve 2, where its pressure decreases and its temperature drops, forming low-pressure subcooled liquid ammonia. The low-pressure subcooled liquid ammonia enters evaporator 210, where it absorbs external heat and evaporates into ammonia gas, achieving the refrigeration effect. The evaporated ammonia gas stream enters the absorber 230 after passing through the cold side of the cooler 220, where it is absorbed by the dilute ammonia solution from the generator 260, forming a concentrated ammonia solution. The concentrated ammonia solution is then pumped back to the generator 260 by the ammonia pump 240, completing the cycle. During the flow of the concentrated ammonia solution from the absorber 230 to the generator 260, it passes through the heat exchanger 250, where it exchanges heat with the dilute ammonia solution flowing from the generator 260 to the absorber 230, improving system efficiency.

[0057] In some embodiments, the ammonia absorption refrigeration system 200 further includes a pressure and temperature acquisition device, a calculation device, and a control device (not shown in the figure). The pressure and temperature acquisition device is located at the outlet of the evaporator 210 and is used to monitor the outlet pressure and outlet temperature of the evaporator 210. The calculation device is signal-connected to the pressure acquisition device and is used to calculate the corresponding saturation temperature based on the outlet pressure. The calculation device is also used to calculate the superheat value (i.e., the difference between the outlet temperature and the saturation temperature) based on the saturation temperature and the outlet temperature. The superheat value is a key parameter reflecting the refrigerant state within the evaporator, and its magnitude directly affects the system's refrigeration efficiency and stability. The control device is signal-connected to the calculation device and is used to receive the superheat value and compare it with a preset set range. In response to the superheat value exceeding or falling below the set range, the control device sends an operating signal to the controller 3 of the combined throttling device 100. The operating signal instructs the controller 3 to control the linear displacement of the output shaft 11.

[0058] Specifically, the setting range includes a maximum setting threshold and a minimum setting threshold. When the superheat value exceeds the maximum threshold of the setting range, the control device sends a positive operation signal to the controller 3. The positive operation signal is used to instruct the controller 3 to drive the stepper motor 1 and control the displacement of the output shaft 11 to increase the opening of the needle valve 2, thereby increasing the ammonia flow rate into the evaporator 210 and reducing the superheat. When the superheat value is lower than the minimum threshold of the setting range, the control device sends a reverse operation signal. The reverse operation signal is used to instruct the controller 3 to drive the stepper motor 1 and control the displacement of the output shaft 11 to decrease the opening of the needle valve 2, reduce the ammonia flow rate, and increase the superheat.

[0059] Thus, this closed-loop control mechanism can adjust the needle valve opening in real time to ensure that the superheat is always kept within the set range, thereby optimizing the heat exchange efficiency of the evaporator and avoiding system performance degradation or equipment damage caused by excessively high or low superheat. Furthermore, the controller 3 can dynamically adjust the strength of the control signal according to the magnitude of the superheat deviation, for example, by increasing or decreasing the number of pulse signals to precisely control the displacement of the output shaft 11 of the stepper motor 1, thereby achieving finer flow regulation. Through this intelligent control design, the ammonia absorption refrigeration system 200 can not only achieve a highly efficient and stable refrigeration cycle, but also significantly reduce energy consumption and maintenance costs.

[0060] In some embodiments, the controller 3 is used to calculate the opening change based on a preset function between the difference between the superheat value and the maximum or minimum set threshold and the opening change of the needle valve 2, and transmit the opening change to the stepper motor 1 in the form of a pulse signal.

[0061] Specifically, controller 3 first receives the superheat value from the computing device and compares it with the maximum or minimum set threshold to calculate the superheat deviation (i.e., the difference between the superheat value and the set threshold). Then, controller 3 converts the superheat deviation into a change in the needle valve opening according to a preset function. The preset function is typically designed based on the system's thermodynamic characteristics and the needle valve's flow regulation characteristics; for example, for every 1°C increase in superheat deviation, the corresponding needle valve opening needs to increase by 0.1 mm. Controller 3 then converts the calculated opening change into the number of pulse signals required by stepper motor 1. For example, if the needle valve 2 opening needs to increase by 0.1 mm, and each pulse signal received by stepper motor 1 moves the output shaft by 0.01 mm, controller 3 will generate 10 pulse signals and transmit them to stepper motor 1. Upon receiving the pulse signals, stepper motor 1 rotates gradually according to a preset step angle (e.g., 1.8°), converting the rotational motion into axial displacement of the output shaft 11 via a ball screw mechanism, thereby moving the valve needle 22 of needle valve 2 to achieve precise opening adjustment.

[0062] Thus, controller 3 achieves a precise mapping between the superheat value and the change in needle valve opening through a preset function, thereby further optimizing the control performance of the ammonia absorption refrigeration system 200. Furthermore, controller 3 can dynamically optimize the preset function based on the real-time operating status of the system. For example, it can use a larger opening change during system startup to quickly stabilize the superheat, and a smaller opening change during steady-state operation to achieve fine adjustment. Through this design, the ammonia absorption refrigeration system 200 can achieve a highly efficient and stable refrigeration cycle.

[0063] The following is based on Figures 1-3 The illustrated embodiment describes the control method of the ammonia absorption refrigeration system 200 provided by this utility model embodiment.

[0064] (1) Before the system is powered on, the opening of needle valve 2 needs to be initially positioned using limit switch 4. Stepper motor 1 moves downward under the control program, driving the valve needle 22 of needle valve 2 to move in the closing direction. When stepper motor 1 touches the lower limit position of limit switch 4, it indicates that the opening of needle valve 2 has reached the minimum value. At this time, stepper motor 1 stops running, completing the initial positioning of needle valve 2. This step ensures that the needle valve is in a known reference position when the system is started.

[0065] (2) During system operation, the temperature and pressure data at the outlet of evaporator 210 are collected in real time, and the current superheat value is calculated based on these data. The real-time superheat value is compared with the set superheat value, and the controller 3 calculates the required opening adjustment of needle valve 2 using a preset algorithm (such as proportional-integral control). Subsequently, the controller 3 generates a corresponding pulse signal to control the direction, speed, and rotation angle of stepper motor 1, thereby driving the valve needle 22 of needle valve 2 to move, achieving precise adjustment of the opening of needle valve 2.

[0066] (3) After the opening of needle valve 2 changes, the system will monitor the changes in temperature, pressure and superheat in real time and feed these data back to controller 3. Controller 3 will recalculate the superheat deviation based on the feedback data and repeat the above adjustment process to continuously adjust the opening of needle valve 2 dynamically.

[0067] Optionally, the controller 3 sends pulse signals to control the speed and direction of the stepper motor 1. In this embodiment, the controller 3 can send pulse signals with a maximum frequency of 100kHz. The controller 3 can have two signal output points: one outputs pulses to control the rotational speed, and the other outputs the direction to control forward and reverse rotation.

[0068] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0070] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0071] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0072] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A combined throttling device for an ammonia water absorption refrigeration system, characterized by, The combined throttling device comprises a stepper motor, a needle valve, a controller and a limit switch, the needle valve is used as a throttling element, the stepper motor comprises an output shaft for outputting linear displacement, the output shaft is connected with a valve needle of the needle valve to convert the output linear displacement into linear displacement of the valve needle, the controller is used for controlling the linear displacement of the output shaft to adjust the opening degree of the needle valve, and the limit switch is connected with the controller and is triggered to send an electric signal to the controller when the needle valve reaches the minimum opening degree and / or the maximum opening degree. The limit switch comprises a first limit switch and a second limit switch, the first limit switch is installed at a mechanical installation position corresponding to the minimum opening degree position of the needle valve, and the second limit switch is installed at a mechanical installation position corresponding to the maximum opening degree position of the needle valve.

2. The combination throttling device of claim 1, wherein The combined throttling device comprises a connecting piece, the connecting piece connects the output shaft and the valve needle, and linear displacement of the output shaft is transmitted to the valve needle through the connecting piece.

3. The combination throttling device of claim 1, wherein 4. The combined throttling device according to claim 3, wherein the connecting piece is provided with a first groove and a second groove at two ends respectively, the output shaft of the stepper motor is fixed in the first groove, and the valve needle of the needle valve is fixed in the second groove.

5. The combined throttling device according to claim 4, wherein two threaded holes are formed in the side of the connecting piece, and the output shaft and the valve needle are fixed by screws through the threaded holes respectively. The combined throttling device comprises a frame, the stepper motor, the needle valve and the limit switch are all installed on the frame. The combined throttling device comprises a frame, the stepper motor, the needle valve and the limit switch are all installed on the frame. The combined throttling device comprises an evaporator, an absorber, a generator, a condenser and a combined throttling device, the combined throttling device is any one of the combined throttling devices in claims 1-6, the evaporator is communicated with the absorber, the absorber is communicated with the generator, the generator is communicated with the condenser, the condenser is communicated with the evaporator, and the needle valve of the combined throttling device is connected between the condenser and the evaporator. The combined throttling device further comprises an ammonia pump connected between the absorber and the generator.

6. The combination throttling device of claim 1, wherein, The combined throttling device further comprises a heat exchanger, a cold side inlet of the heat exchanger is communicated with the absorber, a cold side outlet of the heat exchanger is communicated with the generator, a hot side inlet of the heat exchanger is communicated with the generator, and a hot side outlet of the heat exchanger is communicated with the absorber. The combined throttling device further comprises a subcooler, a cold side inlet of the subcooler is communicated with the evaporator, a cold side outlet of the subcooler is communicated with the absorber, a hot side inlet of the subcooler is communicated with the condenser, and a hot side outlet of the subcooler is communicated with the needle valve.

7. An ammonia water absorption refrigeration system characterized by comprising: ​ ​ 8. The ammonia water absorption refrigeration system according to claim 7, wherein, ​ ​ 9. The ammonia water absorption refrigeration system according to claim 7, wherein, ​ ​ 10. The ammonia water absorption refrigeration system of claim 7, wherein, ​ ​

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