Method and apparatus for detecting water flow absence in unit, and unit

Abstract

A method and apparatus for detecting water flow absence in a unit, and a unit. The method comprises: after a unit is started up to operate, determining whether a shell and tube pressure P and a shell and tube evaporation temperature Tevaporate meet a first preset condition P≤P1 or Tevaporate≤T1; if the first preset condition is met, determining a time interval t from the startup of the unit to when the first preset condition is met, and determining whether t≤tset is met; if so, increasing the degree of opening of a throttle valve, and further identifying a water flow absence fault on the basis of an air intake temperature Tintake, a water input / output temperature of a shell and tube, and Tevaporate, and executing a corresponding protection action; and if not, maintaining the normal operation of the unit, identifying a water flow absence fault on the basis of P and Tintake, and executing a corresponding protection action. When a unit is started up and during the operation of the unit, water flow absence operation is separately identified by means of operation parameters of the unit, and corresponding handling measures are taken, so as to accurately perform early warning and protection on the water flow absence operation of the unit, thereby avoiding the frost crack of the shell and tube.

Description

Method, device and unit for detecting no water flow in a unit

[0001] This disclosure claims priority to a Chinese patent application filed with the Patent Office of China on November 8, 2023, with application number 202311482892.9 and invention name “A method, device and unit for detecting no water flow in a unit”, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0002] The present disclosure relates to the technical field of units, and in particular to a method and device for detecting no water flow in a unit, and a unit. Background Art

[0003] In existing air-conditioning chillers, shell and tube freezing and cracking often occur when the water pump suddenly stops or the user only turns on the unit without turning on the water pump. Currently, most conventional chillers only protect the shell and tube by detecting the temperature of the water inside the shell and tube, without any special protection and control for no-water flow operation. No-water flow operation of the chiller will cause the shell and tube to freeze and crack.

[0004] Currently, no effective solution has been proposed to the problem in related technologies that the unit cannot provide accurate protection and precise feedback when operating without water flow.

[0005] Summary of the Invention

[0006] The present disclosure provides a method and device for detecting no water flow in a unit, and a unit, so as to solve the problem in the related art that no water flow in the unit can cause inaccurate protection and precise feedback.

[0007] To solve the above technical problems, the present disclosure provides a method for detecting no water flow in a unit, wherein the method comprises:

[0008] After the unit is started up, determine the shell and tube pressure P and shell and tube evaporation temperature T 蒸 Whether the first preset condition is met: P≤P1, or T 蒸 ≤T1; where P1 is the first threshold of shell and tube pressure, and T1 is the first threshold of shell and tube evaporation temperature;

[0009] When the first preset condition is met, determine the time interval t from the start of the unit to the satisfaction of the first preset condition, and judge whether it satisfies: t≤the set initial running time t 设 ;

[0010] If yes, then adjust the opening of the throttle valve upwards and further adjust the opening according to the suction temperature T 吸 , shell and tube inlet and outlet water temperature, T 蒸 Identify the no-water flow fault and perform corresponding protection actions; wherein the throttle valve is provided on the pipeline between the shell and tube and the condenser;

[0011] If no, keep the unit in normal operation and adjust the unit according to P and T during normal operation. 吸 Identify no-water flow faults and perform corresponding protection actions.

[0012] In some embodiments, determining P and T 蒸 After determining whether the first preset condition is met, the method further includes: if the first preset condition is not met, maintaining normal operation of the unit.

[0013] In some embodiments, further according to the suction temperature T 吸 , shell and tube inlet and outlet water temperature, T 蒸 Identify no-flow faults and perform corresponding protection actions, including:

[0014] Retest P and T 蒸 , and determine whether the first preset condition is met; if so, detect T 吸 Get the intake temperature change data, detect the inlet and outlet water temperatures to get the inlet and outlet water temperature difference, and according to the intake temperature change data, the inlet and outlet water temperature difference, T 蒸 Identify no-water flow fault and execute corresponding protection action; if not, keep the unit running normally.

[0015] In some embodiments, according to the intake temperature change data, the inlet and outlet water temperature difference, T 蒸 Identify no-flow faults and perform corresponding protection actions, including:

[0016] Determine whether the second preset condition is met: the intake temperature change data ≤ the first preset data, and the inlet and outlet water temperature difference T 差 ≤T 设 ; Among them, T 设 Is the limit value of the inlet and outlet water temperature difference;

[0017] If the second preset condition is met, then at t 设 Internally determine whether the third preset condition is met: P≤P2, or T 蒸 ≤T2; where P2 is the second threshold of shell and tube pressure, T2 is the second threshold of shell and tube evaporation temperature, P2<P1, T2<T1; if so, the unit is controlled to shut down, a no-water flow fault is fed back, and the no-water flow protection action is activated; if not, the unit is controlled to standby and restart after the preset shutdown time of the compressor is reached;

[0018] If the second preset condition is not met, the opening of the throttle valve is adjusted upwards. 设 If yes, the unit is shut down, a water flow failure is fed back, and the low pressure protection action is started; if no, the unit is kept in normal operation, and the unit is kept in normal operation according to P and T. 吸 Identify a no-flow fault.

[0019] In some embodiments, after the unit is controlled to be in standby mode and restarted after the compressor is shut down for a preset period of time, the method further includes: after the cumulative number of restarts reaches a preset number, the unit is controlled to shut down, a no water flow fault is fed back, and a no water flow protection action is started.

[0020] In some embodiments, the no-water-flow protection action includes: controlling the compressor to be unable to start automatically, and the fault needs to be manually cleared; the low-pressure protection action includes: automatically clearing the fault and restarting after the preset shutdown time of the compressor is reached.

[0021] In some embodiments, during normal operation of the unit, according to P and T 吸 Identify no-flow faults and perform corresponding protection actions, including:

[0022] Detect the shell and tube pressure P; when it is detected that P≤P1, determine whether the throttle valve has been closed within t1 time before the current time; where t1 is the preset value; if there is no closing action, further determine whether the water pump signal is connected; if the water pump signal is connected, then according to P and T 吸 Identify no-water flow faults and perform corresponding protection actions.

[0023] In some embodiments, if the water pump signal is on, then according to P and T 吸 Identify no-flow faults and perform corresponding protection actions, including:

[0024] Determine whether the fourth preset condition is met: P≤P2, and the suction temperature change data is greater than the second preset data; if so, control the compressor to shut down, feedback the no water flow fault: water pump failure or water pump blockage, and start the no water flow protection action; if not, increase the opening of the throttle valve, then re-test P, and re-determine whether P≤P1 is met.

[0025] In some embodiments, after further determining whether the water pump signal is connected, the method further includes: if the water pump signal is not connected, controlling the compressor to shut down and feeding back a no water flow fault: the water pump is not turned on.

[0026] In some embodiments, after determining whether there is a throttle valve closing action within time t1 before the current time, the method further includes: if there is a relevant small action, maintaining normal operation of the unit and determining that there is no abnormality in the unit.

[0027] The present disclosure also provides a unit no water flow detection device, wherein the device comprises:

[0028] The detection module is set to judge the shell and tube pressure P and shell and tube evaporation temperature T after the unit is started and running. 蒸 Whether the first preset condition is met: P≤P1, or T蒸 ≤T1; where P1 is the first threshold of shell and tube pressure, and T1 is the first threshold of shell and tube evaporation temperature;

[0029] The judgment module is configured to determine the time interval t from the start of the unit to the satisfaction of the first preset condition when the first preset condition is met, and judge whether the following conditions are met: t≤the set initial operation time t 设 ;

[0030] The first processing module is configured to increase the opening of the throttle valve if the judgment result of the judgment module is yes, and further adjust the opening of the throttle valve according to the suction temperature T 吸 , shell and tube inlet and outlet water temperature, T 蒸 Identify the no-water flow fault and perform corresponding protection actions; wherein the throttle valve is provided on the pipeline between the shell and tube and the condenser;

[0031] The second processing module is configured to maintain the normal operation of the unit if the judgment result of the judgment module is no, and to adjust the unit according to P and T during the normal operation of the unit. 吸 Identify no-water flow faults and perform corresponding protection actions.

[0032] The present disclosure also provides a unit, wherein the unit includes: a compressor, a condenser, a shell and tube connected in sequence, a throttle valve arranged on the pipeline between the shell and tube and the condenser, and the above-mentioned unit no water flow detection device.

[0033] The present disclosure also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the above-mentioned method for detecting no water flow in a unit is implemented.

[0034] By applying the technical solution disclosed in the present invention, when the unit is started up and during operation, the water flow operation can be identified through the unit's operating parameters, and corresponding treatment measures can be implemented, which can accurately provide early warning and protection for the water flow operation of the unit and avoid shell and tube freezing and cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a schematic diagram of the structure of a chiller system according to an embodiment of the present disclosure;

[0036] FIG2 is a flow chart of a method for detecting no water flow in a unit according to an embodiment of the present disclosure;

[0037] FIG3 is a flow chart of water-free operation control during unit startup according to an embodiment of the present disclosure;

[0038] FIG4 is a flow chart of the control of no-water flow operation during stable operation of the unit according to an embodiment of the present disclosure;

[0039] FIG5 is a structural block diagram of a device for detecting no water flow in a unit according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the present disclosure more clear, the present disclosure will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present disclosure, rather than all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present disclosure without creative effort are intended to fall within the scope of protection of the present disclosure.

[0041] The terms used in the embodiments of the present disclosure are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. The singular forms "a," "an," "the," and "the" used in the embodiments of the present disclosure and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0042] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0043] It should be understood that although the terms "first," "second," "third," etc. may be used to describe the preset conditions in the embodiments of the present disclosure, these preset conditions should not be limited to these terms. These terms are merely used to distinguish the preset conditions. For example, without departing from the scope of the embodiments of the present disclosure, the first preset condition may also be referred to as the second preset condition, and similarly, the second preset condition may also be referred to as the first preset condition.

[0044] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0045] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0046] Optional embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0047] Example 1

[0048] FIG1 is a schematic diagram of the structure of a chiller system according to an embodiment of the present disclosure. As shown in FIG1 , the chiller includes at least a compressor 1, a condenser 2 (i.e., a condensing-side heat exchanger), and a shell and tube 4 (i.e., an evaporating-side heat exchanger) connected in sequence. FIG1 shows the water inlet and outlet of the shell and tube 4, with the water inlet being close to the compressor 1 and the water outlet being close to the condenser 2. The chiller also includes a throttle valve 3 (i.e., a throttling device) disposed on the pipeline between the shell and tube 4 and the condenser 2.

[0049] According to an embodiment of the present disclosure, an embodiment of a method for detecting no water flow in a unit is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0050] FIG2 is a flow chart of a method for detecting no water flow in a unit according to an embodiment of the present disclosure. As shown in FIG2 , the method includes the following steps:

[0051] Step S201: After the unit is started, determine the shell and tube pressure P and the shell and tube evaporation temperature T 蒸 Whether the first preset condition is met: P≤P1, or T 蒸 ≤T1.

[0052] P1 is the first threshold of shell and tube pressure, which is usually set between 270kPa and 300kPa for screw chillers (different types of chillers and compressors have different settings). T1 is the first threshold of shell and tube evaporation temperature, which is usually set between -2°C and 0.5°C for screw chillers (different types of chillers and compressors have different settings).

[0053] Step S202: When the first preset condition is met, determine the time interval t from the start of the unit to the meeting of the first preset condition, and judge whether it satisfies: t≤t 设 If yes, go to step S203, if no, go to step S204.

[0054] The above 设 It is to set the initial running time, and its value range can usually be set to 6 minutes to 10 minutes. This time range can ensure that the unit starts and reaches a stable state. If at this time t≤t 设 , indicating that the unit is not in a stable operating state, then step S203 is executed to perform the identification operation and protection feedback operation of the no-water flow operation during the unit startup period. 设, indicating that the unit is already in a stable operating state, then step S204 is executed to perform the identification operation and protection feedback operation of the no-water flow operation during the stable operation of the unit.

[0055] Step S203: Increase the opening of the throttle valve (for example, by 10%), and further adjust the opening according to the intake air temperature T 吸 , shell and tube inlet and outlet water temperature, T 蒸 Identify a no-water flow fault and initiate corresponding protective actions. The throttle valve is located in the pipeline between the shell and tube and the condenser. The inlet and outlet water temperatures include inlet and outlet temperatures. The inlet temperature is detected at the shell and tube inlet, while the outlet temperature is detected at the shell and tube outlet.

[0056] Step S204: Keep the unit in normal operation and set the unit in normal operation according to P and T. 吸 Identify no-water flow faults and perform corresponding protection actions.

[0057] It should be noted that if the judgment result of the above step S201 is that the above first preset condition is not met, it means that the unit is normally started at this time without any abnormal phenomenon, then step S205 is executed to maintain the normal operation of the unit.

[0058] This embodiment identifies water-free operation through the unit's operating parameters when the unit is started and during operation, and implements corresponding treatment measures, which can accurately provide early warning and protection for water-free operation of the unit and avoid shell and tube freezing and cracking.

[0059] 1) The following is a detailed introduction to the identification operation and protection feedback operation of the water-free operation during the unit startup in step S203.

[0060] After confirming that the time interval t from the start of the unit to the satisfaction of the first preset condition satisfies: t≤t 设 Afterwards, test P and T again 蒸 , and determine whether the first preset condition is met. That is, observe whether the shell and tube pressure and shell and tube evaporation temperature have improved to avoid false alarms caused by fluctuations during startup.

[0061] If the first preset condition mentioned above is not met, it means that the unit is in the process of self-regulation, and the unit should continue to operate normally.

[0062] If the first preset condition is still met, it means that the unit is operating abnormally and it is necessary to test the parameters related to no water flow: Test T 吸 Get the suction temperature change data (for example: suction temperature change rate, suction temperature drop value, etc.), detect the inlet and outlet water temperatures to get the inlet and outlet water temperature difference (inlet and outlet water temperature difference = inlet water temperature - outlet water temperature), according to the suction temperature change data, inlet and outlet water temperature difference, T 蒸Identify no-water flow faults and execute corresponding protection actions. Specifically:

[0063] Determine whether the second preset condition is met: the intake temperature change data ≤ the first preset data, and the inlet and outlet water temperature difference T 差 ≤T 设 ; Among them, T 设 It is the limit value of the inlet and outlet water temperature difference.

[0064] In this embodiment, the intake air temperature change data is the intake air temperature change rate ΔT 吸 The intake temperature change data ≤ the first preset data can be: ΔT 吸 ≤ΔT 设 It should be noted that according to the actual operation of the unit without water flow, when the unit is started without water flow, the inlet and outlet water temperatures do not change much, so the inlet and outlet water temperature difference is not large, T 差 It can be set to 0-0.3℃; the suction temperature also does not change much, so the first preset data ΔT 设 It can be set to 1-3°C.

[0065] If the suction temperature change data is a drop in suction temperature, then the suction temperature change data ≤ the first preset data may be: the drop in suction temperature within 3 minutes ≤ 10-15°C. It should be noted that, in actual practice, during normal unit startup, the suction temperature is initially detected based on the ambient temperature. Therefore, after the compressor starts, the water flow in the evaporator for heat exchange quickly lowers the suction temperature. Therefore, the suction temperature typically drops by at least 15°C within 3 minutes of startup.

[0066] If the second preset condition is met, then determine whether the third preset condition is met within the preset time: P≤P2, or, T 蒸 ≤T2; if yes, the unit is controlled to shut down, a no-water-flow fault is fed back, and the no-water-flow protection action is started; if not, the unit is controlled to standby, and restart after the preset shutdown time of the compressor is reached. After the cumulative number of restarts reaches the preset number, the unit is controlled to shut down, a no-water-flow fault is fed back, and the no-water-flow protection action is started.

[0067] P2 is the second threshold for shell and tube pressure, also known as the protection pressure point, and is typically set between 180kPa and 230kPa (different units and compressors have different settings), with P2 < P1. T2 is the second threshold for shell and tube evaporation temperature, and is typically set between -15°C and -6°C (different units and compressors have different settings), with T2 < T1.

[0068] If the second preset condition is not met, it means that the parameter change is caused by the normal adjustment of the unit, then the opening of the throttle valve is adjusted upward, and it is judged whether the third preset condition is met within the preset time; if so, the unit is controlled to shut down, the water flow failure is fed back, and the low pressure protection action is started; if not, the unit is kept in normal operation, and the unit is set to operate according to P and T during normal operation. 吸 Identify a no-water-flow fault, that is, perform an identification operation and a protection feedback operation of no-water-flow operation during stable operation of the unit.

[0069] It should be noted that the aforementioned no-water flow protection action includes: controlling the compressor to be unable to automatically start, requiring manual clearing of the fault. In this case, there is no water flow but the water temperature in the shell and tube is high. The aforementioned low-pressure protection action includes: automatically clearing the fault and restarting the compressor after the preset shutdown time has expired.

[0070] The above describes the identification operation and protection feedback operation of water-free operation during unit startup. When the unit is started, the inlet and outlet water temperature difference, suction temperature change rate and other parameters are detected, and the shell and tube pressure and shell and tube evaporation temperature thresholds are determined. The throttling device (throttle valve) is adjusted to verify whether the water-free phenomenon occurs, and the unit operation is controlled, faults are fed back and protection operations are performed in a timely manner.

[0071] 2) The following is a detailed introduction to the identification operation and protection feedback operation of the water flowless operation during the stable operation of the unit in step S204.

[0072] After confirming that the time interval t from the start of the unit to the satisfaction of the first preset condition satisfies: t>t 设 After that, the unit enters the stable operation state. The identification operation and protection feedback operation of the no-water flow operation during the stable operation of the unit are as follows:

[0073] Detect shell and tube pressure P;

[0074] When P ≤ P1 is detected, the system determines whether the throttle valve was closed within a time interval t1 prior to the current time. t1 is a preset value. Throttle valve adjustment can cause fluctuations in the shell and tube pressure, which typically manifests within 10 to 20 seconds of throttle valve adjustment. Therefore, t1 can be set within a range of 10 to 20 seconds.

[0075] If there are small movements, the shell and tube pressure fluctuations are caused by the throttle valve adjustment. In this case, keep the unit running normally, make sure there is no abnormality in the unit, and do not perform water flow related tests.

[0076] If there is no closing action, it is necessary to perform a water flow related test: determine whether the water pump signal is connected. If the water pump signal is not connected, the compressor is controlled to shut down and a water flow fault is fed back: the water pump is not turned on.

[0077] If the water pump signal is turned on, then according to P and T吸 Identify a no-water flow fault and initiate the corresponding protection action. Specifically, determine whether the fourth preset condition is met: P ≤ P2, and the suction temperature change data is greater than the second preset data. If so, the compressor is shut down, and a no-water flow fault (water pump failure or blockage) is reported, initiating the no-water flow protection action. If not, increase the opening of the throttle valve, recheck P, and re-determine whether P ≤ P1 is met.

[0078] The above-mentioned intake air temperature change data can be the intake air temperature change rate ΔT 吸 , or it can be the suction temperature drop value. If the suction temperature change data is the suction temperature drop value, then the suction temperature change data > the second preset data can be: the suction temperature drops by > 10°C within 1 minute. It should be noted that, according to actual conditions, during this operation, because the water temperature is already at a low level, if the water is cut off at this time, the refrigerant cannot fully exchange heat, thereby quickly lowering the suction temperature.

[0079] The above introduces the identification operation and protection feedback operation of the no-water flow operation during the stable operation of the unit. When the unit is running stably, different faults are distinguished and fed back according to the low pressure changes, throttle valve adjustment, and water pump status, ensuring that the unit operation is not disturbed and that abnormal conditions are protected in time.

[0080] After the unit is started, this embodiment detects low pressure and evaporation temperature and compares them with relevant data to initially determine whether there is a risk of no-water flow operation. It then detects changes in the inlet and outlet water temperature difference and intake air temperature to provide a verification judgment. Further comparison with relevant data accurately determines the no-water flow phenomenon and provides a warning feedback. During the stable operation of the unit, it distinguishes the impact of throttle valve operation on the unit, and then determines a no-water flow fault based on changes in pressure and intake air temperature under operating conditions and initiates protection feedback. This solves the problem of the related art in which no-water flow operation of the unit cannot provide accurate protection and precise feedback.

[0081] Example 2

[0082] FIG3 is a flow chart of the waterless operation control during the startup of the unit according to an embodiment of the present disclosure. As shown in FIG3 , the process includes the following steps:

[0083] Step S301: During the startup process, the unit shell and tube pressure P and shell and tube inlet and outlet water temperature T are synchronously detected. 进 、T 出 , suction temperature T 吸 , shell and tube evaporation temperature T 蒸 , and simultaneously determine whether P ≤ P1, or T 蒸 Whether ≤T1.

[0084] P1 is the first threshold of shell and tube pressure, which is usually set at 270kPa to 300kPa for screw chillers (different types of units and compressors have different settings). P2 is the second threshold of shell and tube pressure, also known as the protection pressure point, which is usually set in the range of 180kPa to 230kPa (different types of units and compressors have different settings). T1 is the first threshold of shell and tube evaporation temperature, which is usually set at -2°C to 0.5°C for screw chillers (different types of units and compressors have different settings). T2 is the second threshold of shell and tube evaporation temperature, which is usually set in the range of -15°C to -6°C (different types of units and compressors have different settings).

[0085] If P≤P1 or T 蒸 ≤T1, then the unit starts normally, there is no abnormality, and keeps running; if it is satisfied, go to step S302.

[0086] Step S302: Check if P≤P1 or T 蒸 ≤T1 The time t during which the unit has been running.

[0087] a. If t>t 设 (t 设 To set the initial operating time value, the range is usually 6 minutes to 10 minutes. This time range can ensure that the unit starts up and reaches a stable state). That is, the unit is already in a stable operating state. At this time, if there is really no water flow, the control flow in Figure 4 below is executed.

[0088] b. If this phenomenon occurs during the initial operation of the unit, control the throttle valve opening to 10% to see if the shell and tube pressure and evaporation temperature improve, so as to avoid false alarms caused by fluctuations during the startup process.

[0089] Step S303: Open the throttle valve and check again whether P≤P1 or T 蒸 ≤T1.

[0090] a. If not, the unit is in the process of self-regulation and continues to operate in the absence of water flow.

[0091] b. If P≤P1 or T is still satisfied at this time 蒸 ≤T 1， The unit is operating abnormally, and detection of water flow related parameters is performed, that is, entering step S304.

[0092] Step S304: Detect the inlet and outlet water temperature difference T 差 , detect the suction temperature change rate ΔT 吸 , determine whether T is satisfied 差 ≤T 设 And ΔT 吸 ≤ΔT 设 .

[0093] According to the actual operation of the unit without water flow, when the unit is started without water flow, the inlet and outlet water and temperature changes are not large, so the inlet and outlet water temperature difference is not large, T 差 It can be set to 0~0.3℃. The suction temperature also does not change much, so the suction temperature ΔT 设 It can be set to 1-3°C.

[0094] a. If not satisfied, it is determined that the unit is under normal regulation and enters 5 control.

[0095] b. If satisfied, further determine t 设 Is P≤P2 or T 蒸 ≤T2.

[0096] b1. If not, the unit will be in standby mode and restart after the compressor shutdown time is met. The number of restarts will be recorded +1. When the cumulative number reaches 3 (other values ​​can also be set), the unit will respond: no water flow protection, and the compressor will not be allowed to start. The fault must be manually cleared (in this case, there is no water flow but the water temperature in the shell and tube is high);

[0097] b2. If yes, the unit will shut down and the unit will report back: no water flow protection and the compressor will not be allowed to start. The fault must be cleared manually.

[0098] Step S305: At this time, the throttle valve opening is controlled to open 10% again, and t 设 Is P≤P2 or T 蒸 ≤T2.

[0099] a. If yes, the unit will shut down and report the fault: low-pressure protection will be activated, and the fault will be automatically cleared and the unit will restart after the compressor shutdown time is met.

[0100] b. If no, the unit is operating normally.

[0101] In the above embodiment, P is the shell and tube pressure, T 进 is the shell and tube water inlet temperature, T 出 is the shell and tube outlet water temperature, T 吸 is the suction temperature, T 蒸 is the shell and tube evaporation temperature, P1 is the first low pressure threshold, P2 is the second low pressure threshold (P2<P1), T1 is the first shell and tube evaporation temperature threshold, T2 is the second shell and tube evaporation temperature threshold, t 设 T is the initial running time value after startup. 差 is the inlet and outlet water temperature difference (T 差 =T 进 -T 出 ), T 设 is the limit value of the inlet and outlet water temperature difference, ΔT 设 Preset rate of change for suction temperature, ΔT吸 is the rate of change of suction temperature (ΔT 吸 = Suction temperature T 10s ago 10s -Current suction temperature T 吸 ).

[0102] This embodiment proposes an identification operation and protection feedback operation for water-free operation during unit startup. When the unit is started, parameters such as the inlet and outlet water temperature difference and the suction temperature change rate are detected, and the shell and tube pressure and shell and tube evaporation temperature thresholds are determined. The throttling device (throttle valve) is adjusted to verify whether the water-free operation occurs, and the unit operation is controlled, fault feedback is given, and protection operations are executed in a timely manner.

[0103] Example 3

[0104] FIG4 is a flow chart of the control of the no-water flow operation during the stable operation of the unit according to an embodiment of the present disclosure. As shown in FIG4 , the process includes the following steps:

[0105] In step S401, when the unit detects P≤P1 during operation, it then simultaneously checks whether the throttle valve has been adjusted or closed within a period of time t1 before P≤P1. Throttle valve adjustment causes shell and tube pressure fluctuations, which typically manifest within 10 to 20 seconds after the throttle valve adjustment. t1 is set to a range of 10 to 20 seconds.

[0106] a. If there is any adjustment to reduce the pressure, the shell and tube pressure fluctuation is caused by the adjustment of the throttling device. The unit will maintain the current operation state and no water flow related detection will be performed.

[0107] b. If there is no adjustment action, go to step 2 to detect the parameters related to no water flow during operation.

[0108] Step S402: In this case, first detect whether the water pump signal is connected.

[0109] a. If the water pump signal is not connected, the compressor will be immediately shut down and a fault will be reported: the water pump is not turned on.

[0110] b. If the water pump signal is connected, then synchronously detect whether P≤P2 and ΔT 吸 >ΔT 设 ;

[0111] b1. If not, the throttle valve opening is controlled to increase by 10%, and then the process returns to step 1.

[0112] b2. If yes, immediately shut down the compressor and report the fault: no water flow protection, confirming that the water pump is faulty or the water line is blocked.

[0113] This embodiment proposes an identification operation and protection feedback operation for water flow-free operation during stable operation of the unit. When the unit is running stably, different faults are distinguished and fed back based on the low pressure changes, throttle valve adjustment conditions, and water pump status, ensuring that the unit operation is not disturbed and that abnormal conditions are protected in a timely manner.

[0114] Example 4

[0115] Corresponding to the unit no-water-flow detection method described in FIG2 , this embodiment provides a unit no-water-flow detection device, as shown in FIG5 , which is a structural block diagram of the unit no-water-flow detection device. The device includes:

[0116] The detection module 10 is configured to determine the shell and tube pressure P and the shell and tube evaporation temperature T after the unit is started. 蒸 Whether the first preset condition is met: P≤P1, or T 蒸 ≤T1; where P1 is the first threshold of shell and tube pressure, and T1 is the first threshold of shell and tube evaporation temperature;

[0117] The judgment module 20 is connected to the detection module 10 and is configured to determine the time interval t from the start of the unit to the satisfaction of the first preset condition when the first preset condition is met, and to determine whether the following conditions are met: t≤the set initial operation time t 设 ;

[0118] The first processing module 30 is connected to the judging module 20 and is configured to increase the opening of the throttle valve if the judging result of the judging module 20 is yes, and further adjust the opening of the throttle valve according to the intake air temperature T 吸 , shell and tube inlet and outlet water temperature, T 蒸 Identify the no-water flow fault and execute the corresponding protection action; wherein the throttle valve is set on the pipeline between the shell and tube and the condenser;

[0119] The second processing module 40 is connected to the judgment module 20 and is configured to maintain the normal operation of the unit if the judgment result of the judgment module 20 is no, and to adjust the unit according to P and T during the normal operation of the unit. 吸 Identify no-water flow faults and perform corresponding protection actions.

[0120] The unit no-water flow detection device of this embodiment can identify no-water flow operation based on the unit's operating parameters both at startup and during operation, and implement corresponding treatment measures. This has been described in detail previously and will not be repeated here. This allows for accurate warning and protection against no-water flow operation, preventing shell and tube freezing and cracking.

[0121] This embodiment further provides a unit comprising: a compressor, a condenser, a shell and tube connected in sequence, a throttle valve disposed on the pipeline between the shell and tube and the condenser, and the aforementioned unit no-water flow detection device. The device can be used to identify no-water flow operation based on the unit's operating parameters during unit startup and operation, and to implement corresponding treatment measures.

[0122] Example 5

[0123] The embodiments of the present disclosure provide a software configured to execute the technical solutions described in the above embodiments and preferred implementations.

[0124] An embodiment of the present disclosure provides a non-volatile computer storage medium storing computer-executable instructions, which can execute the unit no-water-flow detection method in any of the above method embodiments.

[0125] The above-mentioned software is stored in the above-mentioned storage medium, which includes but is not limited to: a CD, a floppy disk, a hard disk, a rewritable memory, etc.

[0126] The serial numbers of the above-mentioned embodiments of the present disclosure are for description only and do not represent the advantages or disadvantages of the embodiments.

[0127] In the above embodiments of the present disclosure, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0128] In the several embodiments provided in the present disclosure, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0129] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0130] In addition, the functional units in the various embodiments of the present disclosure may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0131] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the relevant technology or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0132] The above-mentioned product can execute the method provided by the embodiment of this disclosure, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in this embodiment, please refer to the method provided by the embodiment of this disclosure.

[0133] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0134] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the above technical solution, in essence, or the part that contributes to the relevant technology, can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. A method for detecting no water flow in a unit, the method comprising: After the unit is started, determine the shell and tube pressure P and shell and tube evaporation temperature T 蒸 Whether the first preset condition is met: P≤P1, or T 蒸 ≤T1; Among them, P1 is the first threshold of shell and tube pressure, and T1 is the first threshold of shell and tube evaporation temperature; When the first preset condition is met, determine the time interval t from the start of the unit to the satisfaction of the first preset condition, and judge whether it satisfies: t≤set initial running time t 设 ; If yes, then the opening of the throttle valve is adjusted upward, and further adjusted according to the suction temperature T 吸 , shell and tube inlet and outlet water temperatures, T 蒸 Identify the no-water flow fault and perform corresponding protection actions; wherein the throttle valve is arranged on the pipeline between the shell and tube and the condenser; If no, keep the unit in normal operation and adjust the unit according to P and T during normal operation. 吸 Identify no-water flow faults and perform corresponding protection actions.

2. The method according to claim 1, wherein: Determine P and T 蒸 After determining whether the first preset condition is met, the method further includes: If the first preset condition is not met, the unit is kept in normal operation.

3. The method according to claim 1, wherein: Further according to the suction temperature T 吸 , shell and tube inlet and outlet water temperatures, T 蒸 Identify no-flow faults and perform corresponding protection actions, including: Check P and T again 蒸 , and determine whether the first preset condition is met; If yes, then detect T 吸 The suction temperature change data is obtained, and the inlet and outlet water temperatures are detected to obtain the inlet and outlet water temperature difference. According to the suction temperature change data, the inlet and outlet water temperature difference, T 蒸 Identify no-water flow faults and perform corresponding protection actions; If no, keep the unit running normally.

4. The method according to claim 3, wherein: According to the suction temperature change data, the inlet and outlet water temperature difference, T 蒸 Identify no-flow faults and perform corresponding protection actions, including: Determine whether the second preset condition is met: the suction temperature change data ≤ the first preset data, and the inlet and outlet water temperature difference T 差 ≤T 设 ; Among them, T 设 It is the limit value of the inlet and outlet water temperature difference; If the second preset condition is met, then at t 设 Determine whether the third preset condition is met: P≤P2, or, T 蒸 ≤T2; where P2 is the second threshold of shell and tube pressure, T2 is the second threshold of shell and tube evaporation temperature, P2<P1, T2<T1; if yes, the unit is controlled to shut down, a water flow failure is fed back, and the water flow protection action is started; if no, the unit is controlled to standby and restart after the preset shutdown time of the compressor is reached; If the second preset condition is not met, the opening of the throttle valve is adjusted upward. 设 Internal judgment The third preset condition is met; if yes, the unit is controlled to shut down, a water flow failure is fed back, and the low pressure protection action is started; if no, the unit is kept in normal operation, and during the normal operation of the unit, the unit is controlled to shut down according to P and T 吸 Identify a no-flow fault.

5. The method according to claim 4, wherein: After the unit is controlled to be in standby mode and the compressor is restarted after reaching a preset shutdown time, the method further includes: When the cumulative restart times reach the preset times, the unit is controlled to shut down, a no-water flow fault is fed back, and the no-water flow protection action is started.

6. The method according to claim 4, wherein: The water flow protection action includes: controlling the compressor to be unable to start automatically, and the fault needs to be cleared manually; The low-pressure protection action includes: automatically clearing the fault and restarting after the preset shutdown time of the compressor is reached.

7. The method according to claim 1, wherein: During normal operation of the unit, according to P and T 吸 Identify no-flow faults and perform corresponding protection actions, including: Detect shell and tube pressure P; When P≤P1 is detected, it is determined whether there is a throttle valve closing action within t1 time before the current time; wherein t1 is a preset value; If there is no closing action, further determine whether the water pump signal is connected; if the water pump signal is connected, then according to P and T 吸 Identify no-water flow faults and perform corresponding protection actions.

8. The method according to claim 7, wherein: If the water pump signal is turned on, then according to P and T 吸 Identify no-flow faults and perform corresponding protection actions, including: Determine whether the fourth preset condition is met: P≤P2, and the intake air temperature change data>the second preset data; If yes, the compressor is controlled to shut down and a water flow failure is fed back: the water pump fails or is blocked, and the water flow protection action is started; If not, adjust the opening of the throttle valve upward, then re-check P, and re-judge whether P≤P1 is satisfied.

9. The method according to claim 7, wherein: After further determining whether the water pump signal is connected, the method further includes: If the water pump signal is not connected, the compressor is controlled to shut down and a no water flow fault is fed back: the water pump is not turned on.

10. The method according to claim 7, wherein: After determining whether there is a throttle valve closing action within a time t1 before the current time, the method further includes: If there are any minor movements, keep the unit running normally and make sure there is no abnormality in the unit.

11. A unit no water flow detection device, the device comprising: The detection module is set to determine the shell and tube pressure P and shell and tube evaporation temperature T after the unit is started and operated. 蒸 Whether the first preset condition is met: P≤P1, or T 蒸 ≤T1; Among them, P1 is the first threshold of shell and tube pressure, and T1 is the first threshold of shell and tube evaporation temperature; The judgment module is configured to determine the time interval t from the start of the unit to the satisfaction of the first preset condition when the first preset condition is met, and judge whether the following is satisfied: t≤the set initial operation time t 设 ; The first processing module is configured to increase the opening of the throttle valve if the judgment result of the judgment module is yes, and further adjust the opening of the throttle valve according to the suction temperature T 吸 , shell and tube inlet and outlet water temperatures, T 蒸 Identify the no-water flow fault and perform corresponding protection actions; wherein the throttle valve is arranged on the pipeline between the shell and tube and the condenser; The second processing module is configured to maintain the normal operation of the unit if the judgment result of the judgment module is no, and to adjust the unit according to P and T during the normal operation of the unit. 吸 Identify no-water flow faults and perform corresponding protection actions.

12. A unit, comprising: A compressor, a condenser, a shell and tube connected in sequence, a throttle valve arranged on the pipeline between the shell and tube and the condenser, and a water flow detection device for the unit as claimed in claim 11.

13. A computer-readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the method according to any one of claims 1 to 10.

Images