Condenser anti-freezing method and refrigerating unit

Abstract

The invention provides a refrigerating unit condenser anti-freezing method and a refrigerating unit. The refrigerating unit condenser anti-freezing method comprises the steps that the unit receives a shutdown signal; a compressor is controlled to reduce the load to a preset load, and the opening degree of a throttling valve is increased to a preset opening degree; when the pressure of the condenser rises to the preset pressure of the condenser, the compressor is closed; after the compressor is closed, when the difference between the pressure of the condenser and the suction pressure is smaller than or equal to the preset high-low pressure difference, the throttling valve is closed, and in the system shutdown process, the load of the compressor is reduced, and the opening degree of the throttling valve is increased, so that refrigerants are smoothly migrated; a low-temperature refrigerant can be prevented from returning to the condenser to freeze the heat exchange tube, physical damage caused by freezing is avoided, and the stability and reliability of the unit are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of air conditioning, and in particular to a condenser antifreeze method and a refrigeration unit. Background Art

[0002] During the operation of the low-temperature refrigeration unit, the operating temperature of the evaporator is lower than 0°C, and the temperature of the condenser is generally higher than 10°C. Therefore, antifreeze needs to be added to the heat exchange medium in the evaporator, while water can be used as the heat exchange medium in the condenser. However, after the unit is shut down, the compressor stops working, and the condenser with higher pressure and higher temperature will be connected to the evaporator with low pressure and low temperature, and under the action of temperature and pressure, the refrigerant in the condenser will migrate to the evaporator. During the refrigerant migration process, the refrigerant in the condenser continues to evaporate and absorb heat, causing the temperature and pressure in the condenser to eventually balance with the low-temperature and low-pressure evaporator, which may be lower than 0°C, causing the heat exchange medium water in the condenser heat exchange tube to freeze. The water in the heat exchange tube expands in volume after freezing, which will cause the heat exchange tube to be broken, causing the refrigerant to leak into the water system, and the unit cannot operate normally. Summary of the invention

[0003] In order to solve the technical problem in the prior art that water in the condenser heat exchange tube breaks the tube due to low temperature caused by refrigerant migration, the present invention provides a condenser antifreeze method and a refrigeration unit.

[0004] The technical solution adopted by the present invention is:

[0005] The present invention proposes a method for antifreezing a condenser of a refrigeration unit, comprising the steps of:

[0006] The unit received a shutdown signal;

[0007] Control the compressor to reduce the load to a preset load and increase the throttle valve opening to a preset opening;

[0008] When the condenser pressure rises to the preset condenser pressure, the compressor is turned off; after the compressor is turned off, the throttle valve is closed when the condenser pressure minus the suction pressure is less than or equal to the preset high and low pressure difference.

[0009] The refrigeration unit condenser antifreeze method proposed by the present invention also includes the following steps:

[0010] The unit enters a shutdown state after shutting down the compressor and the throttle valve;

[0011] According to the temperature parameters of the condenser, the operating state of the cooling water pump is controlled or an antifreeze alarm is issued to prevent the heat exchange tubes of the condenser from freezing.

[0012] Furthermore, controlling the operating state of the cooling water pump according to the temperature parameter of the condenser specifically includes:

[0013] Determine whether the antifreeze temperature of the heat exchange tube is lower than the preset antifreeze temperature;

[0014] If yes, start the cooling water pump;

[0015] If not, determine the cooling water pump operation logic according to the condenser temperature.

[0016] Further, the determining of the cooling water pump operation logic according to the condenser temperature includes:

[0017] Determine whether the condenser temperature is less than the preset condenser antifreeze temperature;

[0018] If yes, control the cooling water pump to enter a self-circulation mode and start and stop periodically;

[0019] If not, return to shutdown state.

[0020] Furthermore, issuing an antifreeze alarm according to the temperature parameters of the condenser specifically includes:

[0021] Determine whether the antifreeze temperature of the heat exchange tube is less than the antifreeze temperature alarm value of the heat exchange tube;

[0022] If so, an antifreeze alarm is issued;

[0023] If not, cancel the alarm.

[0024] Preferably, the preset load is a preset minimum load, and the preset opening is a preset maximum opening.

[0025] Furthermore, after the compressor is controlled to reduce the load to a preset load, the cooling water pump is turned off.

[0026] Furthermore, after the compressor is controlled to reduce the load to a preset load, a bypass valve of the cooling water circuit is opened to increase the cooling water temperature.

[0027] The present invention also proposes a refrigeration unit, comprising: a compressor, a condenser, a throttle valve and an evaporator, wherein a heat exchange pipe connected to a cooling water circuit is horizontally arranged inside the condenser, and a cooling water pump is arranged in the cooling water circuit. The above-mentioned antifreeze method for the refrigeration unit condenser is used to prevent the heat exchange pipe from freezing and cracking.

[0028] Furthermore, a temperature sensor for detecting the antifreeze temperature of the heat exchange tube is provided on the heat exchange tube located at the bottom of the condenser.

[0029] Compared with the prior art, the present invention reduces the compressor load and increases the throttle valve opening during system shutdown to allow the refrigerant to migrate smoothly, and then closes the compressor and the throttle valve. This can prevent the low-temperature refrigerant from returning to the condenser and freezing the heat exchange tubes, avoid physical damage caused by ice, and ensure the stability and reliability of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 is a flow chart in an embodiment of the present invention;

[0032] Figure 2 A flowchart in a specific embodiment of the present invention;

[0033] Figure 3 This is a control flow chart after shutdown in a specific embodiment of the present invention;

[0034] Figure 4 It is a structural schematic diagram of an embodiment of the present invention;

[0035] Figure 5 It is an end view of the condenser in the embodiment of the present invention.

[0036] 1. Compressor;

[0037] 2. Condenser;

[0038] 21. Heat exchange tube;

[0039] 3. Throttle valve;

[0040] 4. Evaporator;

[0041] 5. Cooling water pump;

[0042] 6. Check valve. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0045] In order to prevent the water in the heat exchange tube from expanding in volume after freezing and causing the heat exchange tube to burst, the prior art generally uses the following two solutions to avoid freezing damage:

[0046] The first one is to cut off the liquid circuit and configure the throttle valve before the evaporator as an electronic expansion valve that can be shut off.

[0047] The second method is to cut off the gas line and install a check valve in the pipeline between the condenser and the compressor. The above two methods can independently isolate the high-temperature and high-pressure condenser from the low-temperature and low-pressure evaporator. However, in actual use, components such as electronic expansion valves, solenoid valves, and check valves have certain failure rates and leakage rates. In some cases, due to the limitations of the components themselves, the condenser and evaporator cannot be isolated, and the condenser may even be frozen.

[0048] In this regard, the present invention proposes a method for preventing freezing of a condenser of a refrigeration unit, comprising the steps of:

[0049] During the operation of the low-temperature refrigeration unit, the unit receives a shutdown signal;

[0050] Control the compressor to reduce the load to a preset load and increase the throttle valve opening to a preset opening;

[0051] When the condenser pressure rises to the preset condenser pressure, the compressor is turned off. After the compressor is turned off, the throttle valve is closed when the condenser pressure minus the suction pressure is less than or equal to the preset high and low pressure difference.

[0052] The specific principle and effect of the above steps are as follows: before the compressor stops, reduce the load and increase the throttle valve opening to promote the refrigerant in the system to migrate to the low-temperature end (evaporator). Maximize the movement of refrigerant in the condenser to the evaporator to avoid refrigerant retention after the condenser stops, causing the condenser temperature to drop below 0°C, thereby freezing the water in the condenser heat exchange tube. Increasing the throttle valve opening can accelerate the transfer of refrigerant, while reducing the load of the compressor can prevent excessive pressure changes.

[0053] As the refrigerant in the condenser is gradually transferred to the evaporator, the pressure inside the condenser begins to rise gradually. When the pressure rises to a preset safety range, the compressor will stop working. This preset pressure is designed to ensure that the system switches within a reasonable pressure range to prevent the pressure and temperature in the condenser from being too high or too low after the compressor stops.

[0054] After the compressor is shut down, the system enters the equilibrium stage, and the pressure difference between the condenser and the evaporator begins to gradually decrease. When the pressure difference between the condenser and the suction pressure of the evaporator reaches the preset high and low pressure difference, the throttle valve closes. Prevent the refrigerant from flowing back or continuing to migrate after shutdown, ensure that there is no excessive residual refrigerant in the condenser, and make the refrigerant level in the condenser lower than the lowest heat exchange tube to avoid direct contact between the refrigerant and the heat exchange tube, that is, prevent the water in the heat exchange tube from freezing and damaging the heat exchange tube. Ensure the stability of the pressure at both ends during shutdown to reduce the risk of temperature fluctuations.

[0055] Through the above steps, the system effectively migrates the refrigerant in the condenser to the evaporator during shutdown, thereby preventing the heat exchange tube from freezing due to low temperature. Through precise control and preset value design, the stable transition of the internal pressure of the refrigeration system is ensured. Reducing the compressor load and increasing the throttle valve opening allows the refrigerant to migrate smoothly. Closing the compressor and throttle valve can prevent the low-temperature refrigerant from returning to the condenser and freezing the heat exchange tube, avoiding physical damage caused by ice, and ensuring the stability and reliability of the unit.

[0056] The antifreeze method of the present invention further comprises the steps of:

[0057] The unit enters shutdown state after shutting down the compressor and throttle valve;

[0058] According to the temperature parameters of the condenser, the operating state of the cooling water pump is controlled or an antifreeze alarm is issued to prevent the heat exchange tubes of the condenser from freezing.

[0059] Although the refrigerant is transferred to the evaporator by closing the throttle valve during shutdown, the throttle valve may still leak. This will cause the refrigerant to slowly flow back to the condenser and gradually increase the refrigerant level in the condenser. Once the refrigerant level rises, it may contact the heat exchange tubes again, causing the water temperature in the heat exchange tubes to drop below the freezing point due to the decrease in the condenser temperature. Therefore, after the unit is shut down, automatic monitoring can be performed based on the temperature parameters of the condenser.

[0060] For example, if the relevant temperature of the condenser is within the safe range, the cooling water pump continues to run to prevent the heat exchange tube from freezing; if the temperature inside the heat exchange tube is close to the freezing point, the system will issue an antifreeze alarm to remind the operator to deal with it in time to prevent the water from freezing and causing the pipe to burst. Ensure that the liquid level changes in the condenser are monitored in real time even in the case of throttle valve leakage or other situations.

[0061] In a specific embodiment, controlling the operating state of the cooling water pump according to the temperature parameter of the condenser specifically includes:

[0062] The temperature of the condenser heat exchange tube is monitored in real time, and a preset antifreeze temperature is preset to determine whether the antifreeze temperature of the heat exchange tube is less than the preset antifreeze temperature;

[0063] If yes, start the cooling water pump;

[0064] If not, determine the cooling water pump operation logic according to the condenser temperature.

[0065] It should be noted that the preset antifreeze temperature is set based on factors such as the freezing point of water in the heat exchange tube and the ambient temperature.

[0066] When the temperature of the heat exchange tube is monitored to be lower than the preset antifreeze temperature, it means that the water temperature may be close to the freezing point. If it is determined that the temperature inside the heat exchange tube is lower than the preset antifreeze temperature, the system will automatically start the cooling water pump. At this time, the operation of the water pump will help to quickly dissipate the low temperature of the heat exchange tube in the condenser through the circulating water flow, preventing the refrigerant temperature in the condenser from further decreasing and being transferred to the water inside through the heat exchange tube. The start of the cooling water pump not only helps to dissipate the low temperature of the condenser, but also prevents the water from freezing in a static state through the movement of the water flow.

[0067] Specifically, the operation logic of the cooling water pump is determined according to the condenser temperature and includes:

[0068] Determine whether the condenser temperature is less than the preset condenser antifreeze temperature;

[0069] If yes, control the cooling water pump to enter a self-circulation mode and start and stop periodically;

[0070] If not, return to shutdown state.

[0071] That is, if the condenser temperature drops below the preset antifreeze temperature, it means that the environmental conditions of the condenser may cause the water in the heat exchange tube to freeze. The preset antifreeze temperature is a safety threshold set by comprehensively considering factors such as the condenser operating environment, refrigerant characteristics, and equipment structure. When the temperature of the condenser is lower than the preset antifreeze temperature, the system will control the cooling water pump to enter the self-circulation mode. In this mode, the cooling water pump will start and stop according to the set cycle to ensure that the hot water in the condenser can maintain a certain fluidity. The periodic start and stop operation can avoid unnecessary long-term operation of the water pump, and also prevent the water from being stationary and easily frozen. Through this self-circulation mode, the system can keep the water temperature in the condenser within a safe range at the lowest energy consumption, which not only avoids water freezing, but also reduces the frequent start and stop of the cold water pump, and extends the service life of the equipment.

[0072] The antifreeze alarm is issued according to the temperature parameters of the condenser, including:

[0073] Determine whether the antifreeze temperature of the heat exchange tube is less than the antifreeze temperature alarm value of the heat exchange tube;

[0074] If so, an antifreeze alarm is issued;

[0075] If not, cancel the alarm.

[0076] When the system is shut down, in addition to controlling the operation of the cooling water pump, the system will also continuously monitor the antifreeze temperature of the heat exchange tube. This monitoring process is based on the set antifreeze temperature alarm value of the heat exchange tube. If the actual temperature of the heat exchange tube is detected to be lower than the alarm value, it means that the water in the heat exchange tube may be close to the freezing point and there is a serious risk of freezing. The purpose of this judgment step is to monitor the temperature of the heat exchange tube in real time to ensure timely response in low temperature environments and avoid irreversible damage to the equipment caused by water freezing.

[0077] When the system determines that the temperature of the heat exchange tube is lower than the preset antifreeze temperature alarm value, the system will immediately issue an antifreeze alarm. The alarm can be specifically prompted by sound and light, or by sending an alarm signal through the control system to remind the operator that the system is facing potential low temperature risks. After receiving the alarm, the operator can take necessary manual or automatic protective measures, such as heating the water pipe, emptying the water in the heat exchange tube, or adding antifreeze, to prevent the heat exchange tube from bursting after the water freezes, and avoid equipment failure caused by the continuous drop in condenser temperature.

[0078] Specifically, the preset load is a preset minimum load, and the preset opening is a preset maximum opening.

[0079] The preset minimum load is usually set based on the minimum energy demand that the system can withstand before safe shutdown. By reducing the load on the compressor to a minimum, the system can reduce the compression of the refrigerant, which helps slow down the circulation of the refrigerant in the system. Avoid pressure imbalance during sudden shutdown and ensure that the system enters the shutdown state stably and safely. When the compressor gradually reduces the load, the throttle valve will gradually open to the preset maximum opening. The purpose of adjusting the throttle valve to the maximum opening is to maximize the migration speed of the refrigerant before shutdown, so that the liquid level inside the condenser can be quickly reduced to a safe range.

[0080] In an alternative embodiment, after the compressor is controlled to reduce the load to a preset load, the cooling water pump is turned off.

[0081] After turning off the cooling water pump, the cooling water flow in the condenser will stop, and the heat in the condenser will no longer be taken away quickly, which will cause the temperature of the refrigerant in the condenser to rise, thereby promoting the increase of condensation pressure. By accelerating the increase of condensation pressure, the system can reduce the refrigerant level in the condenser more quickly, ensuring that it is lower than the lowest position of the heat exchange tube, avoiding direct contact between the condenser and the heat exchange tube.

[0082] In an alternative embodiment, after the compressor is controlled to reduce the load to a preset load, a bypass valve of the cooling water circuit is opened to increase the temperature of the cooling water.

[0083] By adding bypass valves for cooling water inlet and outlet, the cooling water pump is ensured to run continuously, and the cooling water will bypass the condenser, reducing the cooling effect of the cooling water on the condenser, so that the cooling water temperature gradually increases. This not only keeps the temperature of the condenser stable, avoiding a sharp drop in temperature due to the shutdown of the cooling water pump, but also ensures the controllability of the refrigerant when it enters the evaporator and pipeline.

[0084] The present invention also proposes a refrigeration unit, including: a compressor 1, a condenser 2, a throttle valve 3 (the throttle valve is specifically an electronic expansion valve) and an evaporator 4 that are cyclically connected. The compressor 1 is connected to the condenser 2 through a pipeline to send a high-pressure gaseous refrigerant into the condenser 2, and a check valve 6 is provided on the pipeline to prevent the refrigerant from flowing back. Inside the condenser 2, a heat exchange pipe 21 connected to a cooling water circuit is horizontally arranged, and the cooling water circuit is connected to a cooling water pump 5 to ensure that the cooling water can flow into the condenser 2 for heat exchange. The liquid refrigerant in the condenser 2 then flows into the evaporator through the throttle valve to complete the refrigeration cycle. In the cooling water circuit, the cooling water pump is responsible for maintaining the circulation of the cooling water.

[0085] By implementing the above-mentioned condenser antifreeze method, the refrigeration unit can effectively prevent the heat exchange tubes from freezing and cracking, ensuring that the cooling water temperature remains within a safe range; enhance system stability, reduce pressure fluctuations between the condenser and evaporator, and reduce operational risks.

[0086] Specifically, a temperature sensor for detecting the antifreeze temperature of the heat exchange tube is provided on the bottom heat exchange tube in the condenser. The sensor can monitor the water temperature in the bottom heat exchange tube in real time to ensure that it is always within a safe range, thus avoiding the problem of freezing of most heat exchange tubes.

[0087] In addition, a bypass pipeline connecting the water inlet pipe and the water outlet pipe can be set on the cooling water circuit, and a bypass valve can be set on the bypass pipeline. When the bypass valve is opened, the cooling water does not pass through the heat exchange tube, so there is no need to directly shut down the cooling water pump to avoid affecting the system operation.

[0088] In addition, the condenser is also provided with a pressure sensor for detecting the condenser pressure, and a temperature sensor for detecting the condenser temperature, and the specific settings of the sensors are basically consistent with the settings, functions and effects of the existing condensers. The measurement of the suction pressure is also a commonly used parameter in the prior art, which is not the focus of the present invention and will not be described in detail.

[0089] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0090] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0091] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0092] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0093] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for antifreezing a condenser of a refrigeration unit, It is characterized in that Includes steps: The unit received a shutdown signal; Control the compressor to reduce the load to a preset load and increase the throttle valve opening to a preset opening; When the condenser pressure rises to a preset condenser pressure, shutting down the compressor; After shutting down the compressor, close the throttle valve when the condenser pressure minus the suction pressure is less than or equal to the preset high and low pressure difference.

2. The method for antifreezing a condenser of a refrigeration unit according to claim 1, It is characterized in that The unit enters a shutdown state after shutting down the compressor and the throttle valve; According to the temperature parameters of the condenser, the operating state of the cooling water pump is controlled or an antifreeze alarm is issued to prevent the heat exchange tubes of the condenser from freezing.

3. The method for antifreezing a condenser of a refrigeration unit according to claim 2, It is characterized in that The controlling the operating state of the cooling water pump according to the temperature parameter of the condenser specifically includes: Determine whether the antifreeze temperature of the heat exchange tube is lower than the preset antifreeze temperature; If yes, start the cooling water pump; If not, determine the cooling water pump operation logic according to the condenser temperature.

4. The method for antifreezing a condenser of a refrigeration unit according to claim 3, It is characterized in that Determining the cooling water pump operation logic according to the condenser temperature includes: Determine whether the condenser temperature is less than the preset condenser antifreeze temperature; If yes, control the cooling water pump to enter a self-circulation mode and start and stop periodically; If not, return to shutdown state.

5. The method for antifreezing a condenser of a refrigeration unit according to claim 2, It is characterized in that The issuing of an antifreeze alarm according to the temperature parameters of the condenser specifically includes: Determine whether the antifreeze temperature of the heat exchange tube is less than the antifreeze temperature alarm value of the heat exchange tube; If so, an antifreeze alarm is issued; If not, cancel the alarm.

6. The method for antifreezing a condenser of a refrigeration unit according to claim 1, It is characterized in that The preset load is a preset minimum load, and the preset opening is a preset maximum opening.

7. The method for antifreezing a condenser of a refrigeration unit according to claim 1, It is characterized in that After controlling the compressor to reduce the load to the preset load, turn off the cooling water pump.

8. The method for antifreezing a condenser of a refrigeration unit according to claim 1, It is characterized in that After controlling the compressor to reduce the load to the preset load, open the bypass valve of the cooling water circuit to increase the cooling water temperature.

9. A refrigeration unit, include: A compressor, a condenser, a throttle valve and an evaporator, wherein a heat exchange tube connected to a cooling water circuit is horizontally arranged inside the condenser, and a cooling water pump is arranged in the cooling water circuit. It is characterized in that the antifreeze method for the condenser of a refrigeration unit as described in any one of claims 1 to 8 is used to prevent the heat exchange tube from freezing and cracking.

10. The refrigeration unit according to claim 9, It is characterized in that A temperature sensor for detecting the antifreeze temperature of the heat exchange tube is arranged on the heat exchange tube at the bottom of the condenser.

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