Direct expansion refrigeration system with dual line heat economizer

Abstract

The utility model discloses a direct expansion refrigeration system with double pipeline heat exchange economizer, and the pipeline that gas -liquid separator communicates with liquid receiver is equipped with liquid supply regulating valve group. The high pressure liquid refrigerant that the liquid receiver transports exchanges heat with the regenerator, to make refrigerant temperature reduce. The third pipeline of economizer receives the refrigerant that regenerator transports, makes it with the liquid refrigerant in second pipeline carry out again heat exchange and transport to cold air blower. Control device is used for controlling the opening of liquid supply regulating valve group. Liquid supply valve group can stably control the liquid refrigerant state of entering the third pipeline of economizer through adjusting the refrigerant flow that first pipeline transports to gas -liquid separator. The refrigerant in second pipeline is pre -cooled through regenerator, can reduce the temperature fluctuation when refrigerant enters the economizer. The pre -treatment process of double pipeline in the economizer can reduce the interference of external factor to heat exchange process, thereby making the supercooling degree of refrigerant that the economizer discharges more stable.

Description

Technical Field

[0001] This application relates to the field of refrigeration equipment technology, and in particular to a direct expansion refrigeration system with a dual-pipe heat exchanger economizer. Background Technology

[0002] An economizer is a device that provides subcooling to the refrigerant in a refrigeration system through heat exchange, reducing the harmful flash gas generated when it passes through the expansion valve, thereby improving the system's cooling capacity and efficiency. In a refrigeration cycle, the refrigerant, after condensation in the condenser, is typically a saturated liquid. If it directly enters the expansion valve, flash gas (gaseous refrigerant) is easily generated during the pressure reduction process due to localized evaporation. This gas cannot participate in subsequent evaporation and heat absorption, reducing refrigeration efficiency. The economizer introduces another low-temperature refrigerant (usually from a low-pressure stage in the system) to exchange heat with the saturated liquid refrigerant, further lowering its temperature and achieving subcooling (a temperature lower than the saturation temperature at the same pressure). When the subcooled liquid refrigerant passes through the expansion valve, the flash gas is significantly reduced, and more refrigerant enters the evaporator in liquid form to participate in evaporation and heat absorption, thus increasing the cooling capacity per unit mass of refrigerant and improving system efficiency.

[0003] If the flow rates of the two refrigerants in a conventional economizer suddenly change, it can cause an imbalance in the heat exchange ratio between the two, or incomplete gas-liquid separation can cause gaseous refrigerant to enter the economizer for heat exchange, which will disrupt the stability of heat exchange and make the subcooling of the refrigerant discharged from the economizer unstable, thereby reducing the refrigeration efficiency of the entire refrigeration system. Utility Model Content

[0004] This utility model discloses a direct expansion refrigeration system with a dual-pipe heat exchange economizer, which can keep the subcooling degree reached by the refrigerant discharged from the economizer stable.

[0005] To achieve the above objectives, the first aspect of this utility model discloses a direct expansion refrigeration system with a dual-pipe heat exchanger economizer, comprising:

[0006] Evaporative air cooler;

[0007] The compressor is connected to the air cooler via a pipe to receive gaseous refrigerant delivered by the air cooler;

[0008] A condenser, which is connected to the compressor via a pipe to receive gaseous refrigerant delivered by the compressor;

[0009] A liquid receiver, which is connected to the condenser via a pipe, to receive high-pressure liquid refrigerant supplied by the condenser;

[0010] A gas-liquid separator is provided with a first liquid inlet, a first liquid outlet and a first gas inlet. The first liquid inlet is connected to the liquid storage tank through a first pipeline. The first pipeline is provided with a liquid supply regulating valve group, which is configured to regulate the flow rate of refrigerant entering the gas-liquid separator through the first pipeline.

[0011] A regenerator is connected to the liquid receiver via a pipe to receive high-pressure liquid refrigerant supplied by the liquid receiver. The high-pressure liquid refrigerant in the regenerator is configured to exchange heat with the liquid refrigerant in the gas-liquid separator to reduce the temperature of the high-pressure liquid refrigerant.

[0012] An economizer is provided below the gas-liquid separator. The economizer is connected to the first liquid outlet and the first gas inlet via a second pipeline to receive the liquid refrigerant separated by the gas-liquid separator. The economizer is also connected to the regenerator and the air cooler via a third pipeline to reheat the high-pressure liquid refrigerant after heat exchange delivered by the regenerator and then deliver it to the air cooler.

[0013] A control device, which is electrically connected to the liquid supply regulating valve group, is used to control the opening degree of the liquid supply regulating valve group.

[0014] As an optional implementation, the regenerator is disposed inside the gas-liquid separator, and the regenerator is disposed near the bottom of the gas-liquid separator.

[0015] As an optional implementation, the gas-liquid separator is provided with a pressure sensor, which is configured to detect the pressure value inside the gas-liquid separator;

[0016] The control device is electrically connected to the pressure sensor, and the control device is configured to control the opening degree of the liquid supply regulating valve assembly based on the detection result of the pressure sensor.

[0017] As an optional implementation, the direct expansion refrigeration system with a dual-pipe heat exchanger further includes multiple parallel fourth pipes. The first pipe includes a first sub-pipe and a second sub-pipe. The first sub-pipe is connected to multiple fourth pipes, and the second sub-pipe is connected to multiple fourth pipes. The first sub-pipe is also connected to the liquid reservoir, and the second sub-pipe is also connected to the first liquid inlet.

[0018] The liquid supply regulating valve group includes multiple solenoid valves, each of which is respectively installed in the fourth pipeline. The solenoid valves are used to control the opening and closing of the first sub-pipeline and the second sub-pipeline. The control device is used to control the number of solenoid valves activated based on the detection result of the pressure sensor.

[0019] As an optional implementation, the gas-liquid separator is provided with a first liquid level detection element, which is configured to detect the liquid level height of the liquid refrigerant in the gas-liquid separator. The control device is electrically connected to the first liquid level detection element. When the first liquid level detection element detects that the liquid level height of the liquid refrigerant is at a first preset height, it sends an alarm signal to the control device so that the control device displays the alarm signal.

[0020] The gas-liquid separator is equipped with a second liquid level detection element, which is configured to detect the liquid level height of the liquid refrigerant in the gas-liquid separator. The control device is electrically connected to the second liquid level detection element. When the second liquid level detection element detects that the liquid level height of the liquid refrigerant is at a second preset height, it sends an alarm signal to the control device so that the control device displays the alarm signal.

[0021] Wherein, the first preset height is lower than the second preset height.

[0022] As an optional implementation, the gas-liquid separator also has a gas outlet connected to the compressor via a pipe to deliver gaseous refrigerant to the compressor. A filter element is provided on the pipe connecting the gas outlet and the compressor, and the filter element is configured to filter the refrigerant.

[0023] As an optional implementation, the direct expansion refrigeration system with a dual-pipeline heat exchanger further includes an oil separator and an oil cooler. The oil separator has a first inlet, a first outlet, and a second outlet. The first inlet is connected to the compressor via a pipe to receive gaseous refrigerant and liquid lubricating oil delivered by the compressor. The oil separator is configured to separate the gaseous refrigerant and liquid lubricating oil. The oil cooler is connected to the first outlet and the compressor via a fifth pipe to deliver the liquid lubricating oil separated by the oil separator to the compressor after heat exchange. The second outlet is connected to the condenser via a pipe to deliver the liquid refrigerant separated by the oil separator to the condenser.

[0024] As an optional implementation, the oil cooler is also connected to the condenser and the liquid receiver via pipelines, respectively, for exchanging heat with the liquid refrigerant discharged from the condenser and then delivering it to the liquid receiver.

[0025] As an optional implementation, the air cooler includes an evaporator and a fan. The evaporator is connected to the third pipeline via a liquid supply line to receive liquid refrigerant delivered by the third pipeline. The evaporator is also connected to a compressor via a return gas line to deliver gaseous refrigerant to the compressor. The fan is configured to blow out cold air cooled by the evaporator.

[0026] As an optional implementation, the liquid supply line is provided with a first shut-off valve, which is located near the evaporator. The liquid supply line is connected to the second outlet of the oil separator via a gas supply line to receive the gaseous refrigerant discharged from the oil separator. The connection between the gas supply line and the liquid supply line is located closer to the evaporator than the first shut-off valve. The gas supply line is provided with a second shut-off valve, which is configured to control the opening and closing of the gas supply line and the liquid supply line.

[0027] A third shut-off valve is provided on the return gas pipeline, which is located near the evaporator. The return gas pipeline is connected to the gas-liquid separator through the return liquid pipeline to discharge the liquid refrigerant after heat exchange. The connection between the return liquid pipeline and the return gas pipeline is located closer to the evaporator than the third shut-off valve. A fourth shut-off valve is provided on the return gas pipeline, which is configured to control the opening and closing of the return gas pipeline and the return liquid pipeline.

[0028] Compared with the prior art, the beneficial effects of this application are:

[0029] This utility model provides a direct expansion refrigeration system with a dual-pipeline heat exchanger economizer. The gas-liquid separator has a first liquid inlet, a first liquid outlet, and a first gas inlet. The first liquid inlet is connected to a liquid receiver via a first pipeline, which is equipped with a liquid supply regulating valve assembly to adjust the flow rate of refrigerant entering the gas-liquid separator. A regenerator exchanges heat between the high-pressure liquid refrigerant from the liquid receiver and the liquid refrigerant in the gas-liquid separator, thereby lowering the temperature of the high-pressure liquid refrigerant. A third pipeline of the economizer receives the heat-exchanged high-pressure liquid refrigerant from the regenerator, allowing it to exchange heat again with the liquid refrigerant separated from the gas-liquid separator and then be delivered to the air cooler. A control device controls the opening degree of the liquid supply regulating valve assembly. This collaborative control between the liquid supply valve assembly and the gas-liquid separator ensures stable control of the liquid refrigerant entering the third pipeline of the economizer. The liquid supply valve assembly regulates the refrigerant flow rate from the first pipeline to the gas-liquid separator, working in conjunction with the separator's gas-liquid separation function. This prevents gaseous refrigerant from interfering with heat exchange and ensures stable subcooling. Furthermore, the refrigerant in the second pipeline is pre-cooled by a regenerator, reducing temperature fluctuations as it enters the economizer. These pre-treatment processes in each pipeline of the economizer minimize interference from external factors (such as fluctuations in the initial state of the refrigeration system) on the heat exchange process, resulting in a more stable subcooling of the refrigerant discharged from the economizer. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a direct expansion refrigeration system with a dual-pipeline heat exchanger (oil circuit omitted) disclosed in an embodiment of this application;

[0032] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0033] Figure 3 This is a schematic diagram of the structure of a direct expansion refrigeration system with a dual-pipe heat exchanger disclosed in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the structure of a direct expansion refrigeration system (including a defrosting component) with a dual-pipe heat exchanger disclosed in an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100 - Direct expansion refrigeration system with dual-pipe heat exchanger economizer; 1 - Air cooler; 11 - Evaporator; 111 - Liquid supply line; 111a - First shut-off valve; 112 - Gas return line; 112a - Third shut-off valve; 113 - Gas supply line; 113a - Second shut-off valve; 114 - Liquid return line; 114a - Fourth shut-off valve; 2 - Compressor; 3 - Condenser; 4 - Liquid receiver; 5 - Gas-liquid separator; 51 - First liquid inlet; 511 - First line; 511a - Liquid supply regulating valve assembly; 511 b-First sub-pipeline; 511c-Second sub-pipeline; 512-Fourth pipeline; 512a-Solenoid valve; 52-First liquid outlet; 53-First gas inlet; 54-Regenerator; 55-Pressure sensor; 56-First liquid level detection element; 57-Second liquid level detection element; 58-Gas outlet; 59-Filter element; 6-Economizer; 61-Second pipeline; 62-Third pipeline; 7-Oil separator; 71-First inlet; 72-First outlet; 73-Second outlet; 8-Oil cooler; 81-Fifth pipeline. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] In this application, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0039] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain circumstances to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0040] Furthermore, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0041] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0042] Direct expansion refrigeration systems are widely used in cold storage, air conditioning and other fields. Their core feature is that the refrigerant directly evaporates and absorbs heat in the evaporator, achieving refrigeration through a phase change process. Furthermore, the flow and phase change process of the refrigerant directly respond to load changes.

[0043] In a direct expansion refrigeration system, the economizer is a key auxiliary component that improves the performance of the refrigeration system by optimizing the refrigerant circulation process. Its core function is to use the pressure difference of the refrigerant to increase the subcooling of the refrigerant, thereby improving the refrigeration efficiency and operational stability of the refrigeration system.

[0044] If the flow rates of the two refrigerants in the economizer of the related technology suddenly change, it will cause an imbalance in the heat exchange ratio between the two, or incomplete gas-liquid separation will cause gaseous refrigerant to enter the economizer for heat exchange, which will destroy the stability of heat exchange and make the subcooling of the refrigerant discharged from the economizer unstable, thereby reducing the refrigeration efficiency of the entire refrigeration system.

[0045] In view of this, this application discloses a direct expansion refrigeration system with a dual-pipeline heat exchanger economizer. The gas-liquid separator has a first liquid inlet, a first liquid outlet, and a first gas inlet. The first liquid inlet is connected to a liquid receiver via a first pipeline. The liquid supply regulating valve group on the first pipeline is used to control the refrigerant flow rate into the gas-liquid separator via the first pipeline. The regenerator receives the high-pressure liquid refrigerant supplied by the liquid receiver and exchanges heat with it in the gas-liquid separator, thereby lowering the temperature of the high-pressure liquid refrigerant. The third pipeline of the economizer receives the high-pressure liquid refrigerant after heat exchange in the regenerator and exchanges heat again with the liquid refrigerant separated from the gas-liquid separator received in the second pipeline of the economizer before supplying it to the air cooler. The control device is used to control the opening degree of the liquid supply regulating valve group. This allows for the regulation of the refrigerant flow rate from the first pipeline to the gas-liquid separator via the liquid supply valve assembly. Combined with the gas-liquid separator's gas-liquid separation function, this ensures stable control of the liquid refrigerant state entering the third pipeline of the economizer, preventing gaseous refrigerant from interfering with heat exchange and ensuring stable subcooling. Furthermore, the refrigerant in the second pipeline is pre-cooled by the regenerator, reducing temperature fluctuations when it enters the economizer. The pre-treatment processes of each pipeline in the economizer reduce interference from external factors (such as fluctuations in the initial system state) on the heat exchange process, resulting in a more stable subcooling of the refrigerant discharged from the economizer.

[0046] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0047] Please see Figure 1 , Figure 1 This is a schematic diagram of the direct expansion refrigeration system (oil circuit omitted) with a dual-pipe heat exchanger economizer disclosed in this application. In the diagram, solid lines connecting components represent pipelines connecting the various components; solid arrows indicate the refrigerant flow direction, and dashed arrows indicate the lubricating oil flow direction. The direct expansion refrigeration system 100 with a dual-pipe heat exchanger of this application includes a cooler 1, a compressor 2, a condenser 3, a liquid receiver 4, a gas-liquid separator 5, a regenerator 54, an economizer 6, and a control device (not shown in the diagram). The compressor 2 is connected to the cooler 1 via a pipeline to receive gaseous refrigerant supplied by the cooler 1. The condenser 3 is connected to the compressor 2 via a pipeline to receive gaseous refrigerant supplied by the compressor 2. The liquid receiver 4 is connected to the condenser 3 via a pipeline to receive high-pressure liquid refrigerant supplied by the condenser 3. The gas-liquid separator 5 is provided with a first liquid inlet 51, a first liquid outlet 52, and a first gas inlet 53. The first liquid inlet 51 is connected to the liquid receiver 4 via a first pipeline 511. A liquid supply regulating valve assembly 511a is provided on the first pipeline 511, configured to regulate the flow rate of refrigerant entering the gas-liquid separator 5 through the first pipeline 511. A regenerator 54 is connected to the liquid receiver 4 via a pipeline to receive the high-pressure liquid refrigerant supplied by the liquid receiver 4. The high-pressure liquid refrigerant in the regenerator 54 is configured to exchange heat with the liquid refrigerant in the gas-liquid separator 5 to lower the temperature of the high-pressure liquid refrigerant. An economizer 6 is located below the gas-liquid separator 5. The economizer 6 is connected to the first liquid outlet 52 and the first gas inlet 53 via a second pipeline 61 to receive the liquid refrigerant separated by the gas-liquid separator 5. Economizer 6 is also connected to regenerator 54 and air cooler 1 via third pipe 62, for further heat exchange of the high-pressure liquid refrigerant delivered by regenerator 54 to air cooler 1. Control device is electrically connected to liquid supply regulating valve group 511a, for controlling the opening degree of liquid supply regulating valve group 511a.

[0048] The gas-liquid separator 5 receives refrigerant from the liquid receiver 4 through the first pipeline 511, and controls the refrigerant flow rate delivered to the gas-liquid separator 5 through the liquid supply regulating valve group 511a. In this way, when the load in the direct expansion refrigeration system 100 with dual-pipe heat exchange economizer fluctuates (for example, changes in the demand of the air cooler 1 cause changes in the refrigerant circulation volume, such as when the air cooler is used in the cold storage, the cold storage door is frequently opened, allowing hot air from outside to enter, causing the air cooler 1 to need to enhance cooling to offset the new heat load, or when the cold storage switches between refrigeration and freezing modes, the corresponding air cooler 1 needs to increase refrigerant or reduce the refrigerant circulation volume to achieve the temperature of the target mode, etc.), the control device can adjust the opening of the liquid supply regulating valve group 511a in real time to adjust the refrigerant flow rate supplied by the gas-liquid separator 5 to the regenerator 54, so as to avoid the heat exchange efficiency of the regenerator 54 fluctuating due to insufficient or excessive cooling capacity of the liquid refrigerant in the gas-liquid separator 5, thereby stabilizing the subcooling of the refrigerant discharged from the regenerator 54. Furthermore, the gas-liquid separator 5 can stabilize the state of the liquid refrigerant entering the third pipe 62 of the economizer 6, and separate the gaseous refrigerant that cannot participate in heat exchange, so that more liquid refrigerant enters the third pipe 62, thereby avoiding the gaseous refrigerant from interfering with the heat exchange in the economizer 6.

[0049] Secondly, the regenerator 54 pre-cools the refrigerant entering the second pipe 61 of the economizer 6 before it enters the economizer 6 for secondary cooling, achieving subcooling. This further increases the subcooling of the refrigerant, thereby improving the overall cooling efficiency of the direct expansion refrigeration system 100 with a dual-pipe heat exchange economizer. Furthermore, even if the heat exchange efficiency of the regenerator 54 fluctuates, causing fluctuations in the subcooling of the refrigerant, secondary heat exchange through the economizer 6 can compensate and regulate this fluctuation.

[0050] In this way, the pretreatment processes added by the third pipe 62 and the fourth pipe 512 in the economizer 6 can reduce the interference of external factors (such as changes in the cooling demand of the air cooler 1) on the heat exchange process in the economizer 6, thereby making the subcooling of the refrigerant discharged from the economizer 6 to the air cooler 1 more stable.

[0051] It is understood that the refrigerant can be a Freon-like substance (such as R134a, R410A, R22, etc.) or ammonia, etc., and can be selected according to actual usage requirements. This embodiment does not make specific limitations in this regard.

[0052] It is understood that the compressor 2 mentioned above can be a scroll compressor or a screw compressor, etc., and this embodiment does not make specific limitations on it.

[0053] It is understood that the condenser 3 mentioned above can be a finned tube condenser or a shell-and-tube condenser, etc., and this embodiment does not make specific limitations on it.

[0054] It is understood that the aforementioned liquid receiver 4 can be a horizontal liquid receiver 4 or a vertical liquid receiver 4, etc., and this embodiment does not specifically limit it. Usually, the liquid receiver 4 is a high-pressure liquid receiver 4, used to receive the high-pressure liquid refrigerant after condensation by the condenser 3, and used to store excess refrigerant or replenish insufficient refrigerant. Therefore, the liquid refrigerant delivered by the liquid receiver 4 to the regenerator 54 is a high-pressure liquid refrigerant, while the refrigerant received in the gas-liquid separator 5 is a medium-pressure liquid refrigerant after being throttled by the liquid supply regulating valve group 511a.

[0055] Understandably, although both the liquid refrigerant in the gas-liquid separator 5 and the liquid refrigerant in the regenerator 54 are supplied from the receiver 4, the liquid refrigerant in the gas-liquid separator 5 has been throttled by the liquid supply regulating valve group 511a. Due to the Joule-Thomson effect, when the high-pressure fluid passes through the liquid supply regulating valve group 511a, a sudden pressure drop occurs under adiabatic conditions, leading to a temperature change. For the refrigerant in the refrigeration system, throttling usually results in a temperature decrease. Therefore, the temperature of the liquid refrigerant in the gas-liquid separator 5 is lower than the temperature of the liquid refrigerant in the regenerator 54, thus achieving heat exchange between the two.

[0056] It is understood that the gas-liquid separator 5 mentioned above can be a gravity-type gas-liquid separator or a filter-type gas-liquid separator, etc., and this embodiment does not make specific limitations on it.

[0057] It is understood that the aforementioned economizer 6 can be a flash economizer or a plate economizer, etc., and this embodiment does not specifically limit it.

[0058] It is understood that the aforementioned control device may be a programmable logic controller, a microcontroller, or a microprocessor, etc., and this embodiment does not specifically limit it.

[0059] Understandably, the liquid refrigerant in the second pipe 61 is a room-temperature, medium-pressure liquid refrigerant, while the liquid refrigerant in the third pipe 62 is a low-temperature, high-pressure liquid refrigerant. Since the lower the pressure, the lower the saturation temperature of the refrigerant, the temperature of the liquid refrigerant in the second pipe 61 is closer to the saturation temperature under medium pressure, making it easier to absorb heat and evaporate. On the other hand, the temperature difference between the liquid refrigerant in the third pipe 62 and the saturation temperature under high pressure is larger, making it easier to release heat, which further lowers the temperature of the refrigerant, turning it into a supercooled liquid refrigerant.

[0060] It is understandable that the aforementioned regenerator 54 can be installed as a separate device outside the gas-liquid separator 5, or it can be a section of pipeline installed inside the gas-liquid separator 5.

[0061] Taking the regenerator 54 located outside the gas-liquid separator 5 as an example, one of the pipes in the regenerator 54 is used to receive the liquid refrigerant discharged from the liquid storage tank 4, and the other pipe is used to receive the liquid refrigerant discharged from the gas-liquid separator 5, thereby realizing heat exchange between the two liquid refrigerants inside the regenerator 54.

[0062] Taking the regenerator 54 as an example, which is a section of pipe installed inside the gas-liquid separator 5, please refer to [link / reference]. Figure 1 The regenerator 54 is a section of pipe. One end of the pipe is connected to the liquid storage tank 4 through a pipe, and the other end of the pipe is connected to the third pipe 62 of the economizer 6 through a pipe. The regenerator 54 is located near the bottom of the gas-liquid separator 5, that is, the regenerator 54 is located below the liquid refrigerant surface in the gas-liquid separator 5. This allows the liquid refrigerant inside the regenerator 54 to directly exchange heat with the liquid refrigerant in the gas-liquid separator 5, thereby improving the heat exchange efficiency.

[0063] Optionally, a pressure sensor 55 is provided inside the gas-liquid separator 5, which is configured to detect the pressure value inside the gas-liquid separator 5. A control device is electrically connected to the pressure sensor 55 and is configured to control the opening degree of the liquid supply regulating valve assembly 511a based on the detection result of the pressure sensor 55.

[0064] The pressure inside the gas-liquid separator 5 directly affects the refrigerant state output to the second pipe 61 of the economizer 6. The internal pressure of the gas-liquid separator 5 is monitored in real time by the pressure sensor 55. The control device can dynamically adjust the opening of the liquid supply regulating valve group 511a. When the pressure is too high, the opening of the liquid supply regulating valve group 511a is increased, thereby increasing the liquid supply and introducing more high-pressure refrigerant into the gas-liquid separator 5, thus reducing the internal pressure of the gas-liquid separator 5 through a throttling effect. When the pressure is too low, the opening of the liquid supply regulating valve group 511a is decreased, thereby reducing the liquid supply and decreasing the inflow of high-pressure refrigerant into the gas-liquid separator 5, thus maintaining a medium-pressure state inside the gas-liquid separator 5. This closed-loop control ensures that the pressure inside the gas-liquid separator 5 remains stable, ensuring that the refrigerant entering the second pipe 61 of the economizer 6 is always in a "medium-temperature, medium-pressure liquid state," thereby ensuring a stable heat exchange ratio between the second pipe 61 and the third pipe 62 within the economizer 6, and ultimately maintaining a stable subcooling of the refrigerant discharged from the economizer 6.

[0065] It is understood that the pressure sensor 55 mentioned above can be a gauge pressure sensor or a differential pressure sensor, etc., and this embodiment does not make specific limitations on it.

[0066] Please see Figure 1 and Figure 2 , Figure 2 yes Figure 1A partial enlarged view at point A. In some embodiments, the direct expansion refrigeration system 100 with a dual-pipe heat exchanger further includes multiple parallel fourth pipes 512. The first pipe 511 includes a first sub-pipe 511b and a second sub-pipe 511c. The first sub-pipe 511b is connected to multiple fourth pipes 512, and the second sub-pipe 511c is connected to multiple fourth pipes 512. The first sub-pipe 511b is also connected to the liquid receiver 4, and the second sub-pipe 511c is also connected to the first liquid inlet 51. The liquid supply regulating valve group 511a includes multiple solenoid valves 512a, each of which is respectively disposed in the fourth pipe 512. The solenoid valves 512a are used to control the on / off state of the first sub-pipe 511b and the second sub-pipe 511c. The control device is used to control the number of solenoid valves 512a activated according to the detection structure of the pressure sensor 55.

[0067] The liquid supply regulating valve group 511a employs multiple parallel fourth pipelines 512, each equipped with a solenoid valve 512a to control the opening and closing of the first sub-pipeline 511b and the second sub-pipeline 511c. The control device can control the number of solenoid valves 512a activated based on the detection results of the pressure sensor 55. This combination of multiple solenoid valves 512a enables finer flow classification, thereby quickly stabilizing the pressure within the gas-liquid separator 5. Furthermore, this design with multiple solenoid valves 512a ensures that if one solenoid valve 512a in a fourth pipeline 512 fails, the remaining solenoid valves 512a can still operate normally, thus guaranteeing stable operation of the liquid supply regulating function.

[0068] It is understood that the solenoid valve 512a mentioned above can be a ball valve type solenoid valve or a piston type solenoid valve, etc., and this embodiment does not make specific limitations on it.

[0069] Understandably, if the liquid level in the gas-liquid separator 5 is too high, it will affect the gas-liquid separation efficiency, making it easier for the gaseous refrigerant separated in the gas-liquid separator 5 to carry liquid refrigerant, which can cause liquid slugging in the compressor 2. Please continue reading. Figure 1The gas-liquid separator 5 is equipped with a first liquid level detection element 56, which is configured to detect the liquid refrigerant level within the gas-liquid separator 5. A control device is electrically connected to the first liquid level detection element 56. When the first liquid level detection element 56 detects that the liquid refrigerant level is at a first preset height, it sends an alarm signal to the control device, causing the control device to display the alarm signal. The gas-liquid separator 5 is also equipped with a second liquid level detection element 57, which is configured to detect the liquid refrigerant level within the gas-liquid separator 5. The control device is electrically connected to the second liquid level detection element 57. When the second liquid level detection element 57 detects that the liquid refrigerant level is at a second preset height, it sends an alarm signal to the control device, causing the control device to display the alarm signal. The first preset height is lower than the second preset height.

[0070] By installing a first liquid level detector 56 and a second liquid level detector 57 within the gas-liquid separator 5, the liquid refrigerant level is respectively detected to ensure it has reached a first preset height and a second preset height. When the liquid refrigerant level is at either the first or second preset height, an alarm signal is sent to the control device, causing the control device to display the alarm signal. The first preset height is lower than the second preset height. Thus, when the liquid refrigerant level in the gas-liquid separator 5 reaches the first preset height, although it does not directly threaten the safety of the refrigeration system, it deviates from the system's optimal operating range, leading to a decrease in gas-liquid separation efficiency. The alarm signal triggered at this time can prompt operators to perform preliminary inspections and maintenance, preventing the liquid refrigerant level from rising further. When the liquid refrigerant level in the gas-liquid separator 5 reaches the second preset height, the liquid refrigerant has entered a dangerous zone (e.g., submerging the first gas inlet 53). At this point, the liquid refrigerant will rush into the compressor 2, causing liquid slugging in the compressor 2. Simultaneously, the gas-liquid separator 5 completely loses its gas-liquid separation function, leading to cyclic disorder in the entire direct expansion refrigeration system 100 with a dual-pipeline heat exchanger. An alarm signal will then prompt the operator to force a shutdown to minimize accident losses.

[0071] It is understood that the first preset height can be located, for example, in the middle of the gas-liquid separator 5, or slightly above the middle, and the second preset height can be located, for example, near the top of the gas-liquid separator 5. The specific location can be determined according to the actual situation, and this embodiment does not make specific limitations on this.

[0072] It is understood that the first liquid level detection element 56 and the second liquid level detection element 57 mentioned above can both be electrode-type liquid level sensors or capacitive liquid level sensors, etc., and this embodiment does not make specific limitations on this.

[0073] Optionally, the gas-liquid separator 5 also has a gas outlet 58, which is connected to the compressor 2 via a pipe to deliver gaseous refrigerant to the compressor 2. A filter element 59 is provided on the pipe connecting the gas outlet 58 to the compressor 2, and the filter element 59 is configured to filter the refrigerant.

[0074] During the operation of the direct expansion refrigeration system 100 with a dual-pipe heat exchanger economizer, the gaseous refrigerant may carry some solid impurities. If these solid impurities enter the compressor 2, they may scratch the surface of the compressor 2, leading to compressor malfunction. By installing a filter 59 on the pipe connecting the gas outlet 58 and the compressor 2, solid impurities such as metal debris, welding slag, and oxide scale in the refrigerant can be effectively intercepted, thereby reducing the probability of malfunction in the direct expansion refrigeration system 100 with a dual-pipe heat exchanger economizer.

[0075] It is understood that the filter element 59 mentioned above can be a magnetic filter or a centrifugal filter, etc., and this embodiment does not specifically limit it.

[0076] Please see Figure 3 , Figure 3 This is a schematic diagram of the direct expansion refrigeration system with a dual-pipe heat exchanger disclosed in this application. The direct expansion refrigeration system 100 with a dual-pipe heat exchanger further includes an oil separator 7 and an oil cooler 8. The oil separator 7 has a first inlet 71, a first outlet 72, and a second outlet 73. The first inlet 71 is connected to the compressor 2 via a pipe to receive gaseous refrigerant and liquid lubricating oil supplied by the compressor 2. The oil separator 7 is configured to separate the gaseous refrigerant and liquid lubricating oil. The oil cooler 8 is connected to the first outlet 72 and the compressor 2 via a fifth pipe 81, and is used to exchange heat with the liquid lubricating oil separated by the oil separator 7 before supplying it to the compressor 2. The second outlet 73 is connected to the condenser 3 via a pipe to supply the liquid refrigerant separated by the oil separator 7 to the condenser 3.

[0077] The high-pressure gaseous refrigerant discharged from compressor 2 contains some liquid lubricating oil. If this liquid lubricating oil directly enters condenser 3, it will adhere to the heat exchange surface of condenser 3, forming an oil film thermal resistance, thus reducing the condensation efficiency of condenser 3. By setting up an oil separator 7, the gaseous refrigerant and liquid lubricating oil can be separated after the first inlet 71 receives the mixed medium. The separated gaseous refrigerant enters condenser 3 through the second outlet 73, which avoids the interference of the oil film on condensation and ensures the heat dissipation efficiency of condenser 3.

[0078] Furthermore, the lubricating oil discharged from compressor 2 is at a high temperature due to the absorption of mechanical friction heat and compression heat. If it were to flow directly back to compressor 2, it would cause the viscosity of the lubricating oil to increase, making it unable to form an effective oil film on the surfaces of components such as the piston and bearings of compressor 2, thus exacerbating wear. Simultaneously, the increased lubricating oil temperature would reduce its cooling capacity, failing to effectively remove the heat generated by compressor 2 and affecting its service life. By installing an oil cooler 8, the received lubricating oil can be cooled through heat exchange, thereby reducing mechanical wear on compressor 2 and assisting in heat dissipation, allowing it to maintain a normal operating temperature.

[0079] It is understood that the oil separator 7 mentioned above can be a centrifugal oil separator or a filter oil separator, etc., and this embodiment does not make specific limitations on it.

[0080] It is understood that the oil cooler 8 described above can be a shell-and-tube heat exchanger structure or a plate heat exchanger structure, etc., and this embodiment does not make specific limitations on it.

[0081] Alternatively, please continue reading Figure 3 The oil cooler 8 is also connected to the condenser 3 and the liquid receiver 4 via pipelines, and is used to exchange heat with the liquid refrigerant discharged from the condenser 3 and then transport it to the liquid receiver 4.

[0082] The oil cooler 8 receives the liquid refrigerant discharged from the condenser 3, exchanges heat with it, and then transports it to the receiver 4. This allows the liquid refrigerant to exchange heat with the high-temperature lubricating oil, thereby lowering the temperature of the lubricating oil and meeting the lubrication requirements of the compressor 2. Furthermore, the heat exchange medium is the refrigerant discharged from the system itself, eliminating the need for a separate heat exchange medium and thus avoiding additional energy consumption.

[0083] Please see Figure 4 , Figure 4 This is a schematic diagram of a direct expansion refrigeration system (including a defrosting component) with a dual-pipe heat exchanger disclosed in this application. In some embodiments, the air cooler 1 includes an evaporator 11 and a fan (not shown). The evaporator 11 is connected to a third pipe 62 via a liquid supply pipe 111 to receive liquid refrigerant supplied by the third pipe 62. The evaporator 11 is also connected to a compressor 2 via a return gas pipe 112 to deliver gaseous refrigerant to the compressor 2. The fan is configured to blow out cold air cooled by the evaporator 11.

[0084] Subcooled liquid refrigerant is received from the third pipe 62 of the economizer 6 via the liquid supply pipe 111. The refrigerant evaporates and absorbs heat in the evaporator 11, lowering the surface temperature of the evaporator 11 to the target low temperature, thereby cooling the surrounding air. The fan actively blows out the cooled air from the evaporator 11, preventing the cold air from accumulating around the evaporator 11. The combined effect of these two processes ensures that the cooling capacity of the refrigerant is efficiently converted into the overall cooling capacity of the system.

[0085] It is understood that the evaporator 11 described above can be an air-cooled evaporator or a water-cooled evaporator, etc., and this embodiment does not make specific limitations on this.

[0086] It is understood that the aforementioned fan can be an axial flow fan or a centrifugal fan, etc., and this embodiment does not specifically limit it.

[0087] Optionally, a first shut-off valve 111a is provided on the liquid supply line 111, and the first shut-off valve 111a is located near the evaporator 11. The liquid supply line 111 is connected to the second outlet 73 of the oil separator 7 via the gas supply line 113 to receive the gaseous refrigerant discharged from the oil separator 7. The connection point between the gas supply line 113 and the liquid supply line 111 is located closer to the evaporator 11 than the first shut-off valve 111a. A second shut-off valve 113a is provided on the gas supply line 113, and the second shut-off valve 113a is configured to control the opening and closing of the gas supply line 113 and the liquid supply line 111. A third shut-off valve 112a is provided on the return gas line 112, and the third shut-off valve 112a is located near the evaporator 11. The return gas line 112 is connected to the gas-liquid separator 5 via the return liquid line 114 to discharge the liquid refrigerant after heat exchange. The connection point between the return liquid line 114 and the return gas line 112 is located closer to the evaporator 11 than the third shut-off valve 112a. A fourth shut-off valve 114a is provided on the return gas line 112, and the fourth shut-off valve 114a is configured to control the opening and closing of the return gas line 112 and the return liquid line 114.

[0088] Under low-temperature conditions, frost easily forms on the surface of evaporator 11. The frost layer increases thermal resistance and significantly reduces heat exchange efficiency. High-temperature gaseous refrigerant discharged from oil separator 7 is introduced into liquid supply line 111 via gas supply line 113. The connection point between gas supply line 113 and liquid supply line 111 is located between the first shut-off valve 111a and evaporator 11. Liquid return line 114 leads the liquid refrigerant generated during defrosting of evaporator 11 to gas-liquid separator 5. The connection point between liquid return line 114 and gas return line 112 is located between the third shut-off valve 112a and evaporator 11. When the evaporator 11 needs defrosting, by closing the first shut-off valve 111a and the third shut-off valve 112a, and opening the second shut-off valve 113a and the fourth shut-off valve 114a, the high-temperature gaseous refrigerant discharged from the oil separator 7 can be delivered to the evaporator 11 to heat the frost on the surface of the evaporator 11. The refrigerant after heat exchange in the evaporator 11 is then delivered to the gas-liquid separator 5, where the liquid refrigerant undergoes secondary processing using the separation function of the gas-liquid separator 5. This allows the evaporator 11 to flexibly switch between evaporation and defrosting functions, ensuring the stable operation of the entire direct expansion refrigeration system 100 with a dual-pipeline heat exchanger.

[0089] It is understood that the first shut-off valve 111a, the second shut-off valve 113a, the third shut-off valve 112a and the fourth shut-off valve 114a mentioned above can all be electric shut-off valves or pneumatic shut-off valves, etc., and this embodiment does not make specific limitations on this.

[0090] Taking R404A as an example, the temperature and pressure parameters of each node in the direct expansion refrigeration system 100 with a dual-pipe heat exchanger of this application are given in the following table:

[0091]

[0092]

[0093] The refrigerant flow process in the direct expansion refrigeration system 100 with a dual-pipe heat exchanger disclosed in this application will be briefly described below:

[0094] The gaseous refrigerant discharged from compressor 2 enters oil separator 7 and separates from lubricating oil. It then exits through the second outlet 73 to condense into liquid refrigerant in condenser 3. Part of the liquid refrigerant discharged from condenser 3 flows into oil separator 7 for oil cooling, while the other part is stored in receiver 4. The liquid refrigerant discharged from receiver 4 is first transported through liquid supply regulating valve group 511a to gas-liquid separator 5 for gas-liquid separation, and then to the second pipe 61 of economizer 6 for heat exchange before being returned to gas-liquid separator 5. The other liquid refrigerant discharged from receiver 4 is first transported to regenerator 54 for initial heat exchange and cooling, and then to the third pipe 62 of economizer 6 for secondary heat exchange and cooling with the refrigerant in the second pipe 61, achieving subcooling. The subcooled refrigerant is then transported to evaporator 11 for evaporation and heat absorption, and a fan blows the cooled air out of evaporator 11. Evaporator 11 returns the evaporated and heat-absorbed refrigerant to compressor 2, and the cycle repeats. When the evaporator 11 needs to defrost, the first shut-off valve 111a and the third shut-off valve 112a are closed, and the second shut-off valve 113a and the fourth shut-off valve 114a are opened, so that a portion of the gaseous refrigerant discharged from the oil separator 7 is transported to the evaporator 11 to exchange heat with the frost and achieve defrosting. After the heat exchange, the refrigerant is transported to the gas-liquid separator 5.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A direct expansion refrigeration system with a dual-pipe heat exchanger economizer, characterized in that, include: Evaporative air cooler; The compressor is connected to the air cooler via a pipe to receive gaseous refrigerant delivered by the air cooler; A condenser, which is connected to the compressor via a pipe to receive gaseous refrigerant delivered by the compressor; A liquid receiver, which is connected to the condenser via a pipe, to receive high-pressure liquid refrigerant supplied by the condenser; A gas-liquid separator is provided with a first liquid inlet, a first liquid outlet and a first gas inlet. The first liquid inlet is connected to the liquid storage tank through a first pipeline. The first pipeline is provided with a liquid supply regulating valve group, which is configured to regulate the flow rate of refrigerant entering the gas-liquid separator through the first pipeline. A regenerator is connected to the liquid receiver via a pipe to receive high-pressure liquid refrigerant supplied by the liquid receiver. The high-pressure liquid refrigerant in the regenerator is configured to exchange heat with the liquid refrigerant in the gas-liquid separator to reduce the temperature of the high-pressure liquid refrigerant. An economizer is provided below the gas-liquid separator. The economizer is connected to the first liquid outlet and the first gas inlet via a second pipeline to receive the liquid refrigerant separated by the gas-liquid separator. The economizer is also connected to the regenerator and the air cooler via a third pipeline to reheat the high-pressure liquid refrigerant after heat exchange delivered by the regenerator and then deliver it to the air cooler. A control device, which is electrically connected to the liquid supply regulating valve group, is used to control the opening degree of the liquid supply regulating valve group.

2. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 1, characterized in that, The regenerator is located inside the gas-liquid separator, and the regenerator is positioned near the bottom of the gas-liquid separator.

3. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 1, characterized in that, The gas-liquid separator is equipped with a pressure sensor, which is configured to detect the pressure value inside the gas-liquid separator. The control device is electrically connected to the pressure sensor, and the control device is configured to control the opening degree of the liquid supply regulating valve assembly based on the detection result of the pressure sensor.

4. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 3, characterized in that, The direct expansion refrigeration system with a dual-pipe heat exchanger also includes multiple parallel fourth pipes. The first pipe includes a first sub-pipe and a second sub-pipe. The first sub-pipe is connected to multiple fourth pipes, and the second sub-pipe is connected to multiple fourth pipes. The first sub-pipe is also connected to the liquid storage tank, and the second sub-pipe is also connected to the first liquid inlet. The liquid supply regulating valve group includes multiple solenoid valves, each of which is respectively installed in the fourth pipeline. The solenoid valves are used to control the opening and closing of the first sub-pipeline and the second sub-pipeline. The control device is used to control the number of solenoid valves activated based on the detection result of the pressure sensor.

5. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 1, characterized in that, The gas-liquid separator is equipped with a first liquid level detection element, which is configured to detect the liquid level height of the liquid refrigerant in the gas-liquid separator. The control device is electrically connected to the first liquid level detection element. When the first liquid level detection element detects that the liquid level height of the liquid refrigerant is at a first preset height, it sends an alarm signal to the control device so that the control device displays the alarm signal. The gas-liquid separator is equipped with a second liquid level detection element, which is configured to detect the liquid level height of the liquid refrigerant in the gas-liquid separator. The control device is electrically connected to the second liquid level detection element. When the second liquid level detection element detects that the liquid level height of the liquid refrigerant is at a second preset height, it sends an alarm signal to the control device so that the control device displays the alarm signal. Wherein, the first preset height is lower than the second preset height.

6. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 1, characterized in that, The gas-liquid separator also has a gas outlet, which is connected to the compressor via a pipe to deliver gaseous refrigerant to the compressor. A filter element is provided on the pipe connecting the gas outlet and the compressor, and the filter element is configured to filter the refrigerant.

7. The direct expansion refrigeration system with a dual-pipe heat exchanger according to any one of claims 1-6, characterized in that, The direct expansion refrigeration system with a dual-pipeline heat exchanger further includes an oil separator and an oil cooler. The oil separator has a first inlet, a first outlet, and a second outlet. The first inlet is connected to the compressor via a pipe to receive gaseous refrigerant and liquid lubricating oil delivered by the compressor. The oil separator is configured to separate the gaseous refrigerant and liquid lubricating oil. The oil cooler is connected to the first outlet and the compressor via a fifth pipe to deliver the liquid lubricating oil separated by the oil separator to the compressor after heat exchange. The second outlet is connected to the condenser via a pipe to deliver the liquid refrigerant separated by the oil separator to the condenser.

8. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 7, characterized in that, The oil cooler is also connected to the condenser and the liquid receiver via pipelines, and is used to exchange heat with the liquid refrigerant discharged from the condenser and then transport it to the liquid receiver.

9. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 7, characterized in that, The air cooler includes an evaporator and a fan. The evaporator is connected to the third pipeline via a liquid supply line to receive liquid refrigerant delivered by the third pipeline. The evaporator is also connected to the compressor via a return gas line. The fan is configured to blow out cold air cooled by the evaporator.

10. The direct expansion refrigeration system with a dual-pipe heat exchanger according to claim 9, characterized in that, The liquid supply line is equipped with a first shut-off valve, which is located near the evaporator. The liquid supply line is connected to the second outlet of the oil separator via a gas supply line to receive the gaseous refrigerant discharged from the oil separator. The connection between the gas supply line and the liquid supply line is located closer to the evaporator than the first shut-off valve. The gas supply line is equipped with a second shut-off valve, which is configured to control the opening and closing of the gas supply line and the liquid supply line. A third shut-off valve is provided on the return gas pipeline, which is located near the evaporator. The return gas pipeline is connected to the gas-liquid separator through the return liquid pipeline to discharge the liquid refrigerant after heat exchange. The connection between the return liquid pipeline and the return gas pipeline is located closer to the evaporator than the third shut-off valve. A fourth shut-off valve is provided on the return gas pipeline, which is configured to control the opening and closing of the return gas pipeline and the return liquid pipeline.

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