Machine room air conditioner refrigerating system based on air flotation centrifugal compressor and surge monitoring method

Abstract

The invention relates to the technical field of air conditioner refrigerating systems, and provides a machine room air conditioner refrigerating system based on an air flotation centrifugal compressor and a surge monitoring method. The system comprises an air flotation centrifugal compressor, a condenser, an economizer, an evaporator and a compressor driver, and the compressor driver is configured to collect state information of the air flotation centrifugal compressor and conduct surge monitoring on the air flotation centrifugal compressor according to the state information. The air flotation centrifugal compressor is adopted to replace a scroll compressor to be applied to the field of machine room air conditioners, the service life of a unit is longer, the energy efficiency is better, and an oil-free system is easier to maintain and use. In addition, according to the method for monitoring surge of the air flotation centrifugal compressor, devices such as a flow sensor are not needed, the two parameters of speed and power are collected through an inherent controller of the air flotation centrifugal compressor, whether surge occurs or not is judged through logic, and control is more accurate, reliable and rapid.

Description

Technical Field

[0001] The present invention generally relates to the technical field of air conditioning and refrigeration systems. Specifically, the present invention relates to a machine room air conditioning and refrigeration system based on an air-floating centrifugal compressor and a surge monitoring method. Background Art

[0002] Computer room air conditioners are a type of process air conditioners used in data center computer rooms and other places. Since the servers, switches and other information technology (IT) equipment in the data center computer room are running all year round and generating heat, their heat dissipation is high and constant, and they are steady-state heat sources. Therefore, the computer room air conditioner needs to maintain a cooling state all year round to reduce the room temperature and prevent IT equipment from overheating and shutting down. Since the heat exchange effect of the computer room air conditioner's condenser will be affected by the outdoor ambient temperature, the compression ratio of the computer room air conditioning system will also change with changes in the outdoor ambient temperature.

[0003] However, traditional computer room air conditioning systems usually use scroll compressors, so the computer room air conditioning system needs to add a compressor oil return structure, and lubricating oil needs to be replenished as needed during installation and operation and maintenance, which increases the difficulty of maintenance. In addition, scroll compressors also have problems such as short service life, slow frequency increase, low energy efficiency ratio, and large size.

[0004] In addition, since the compressor in the computer room air conditioning system operates under partial load conditions most of the time, the compressor operating speed is usually lower than the design speed. When the load of the computer room is small, the refrigerant circulation volume of the compressor will also decrease. When the flow rate of the compressor is less than the surge limit, it will enter the surge condition and cause damage to the air-floating centrifugal compressor. Therefore, it is necessary to monitor the compressor in the computer room air conditioning system for surge.

[0005] In the prior art, Chinese patent "CN113688510A" discloses a surge prediction method for a centrifugal compression system for a fuel cell vehicle, wherein a surge model of a centrifugal compression system is established based on the Moore Greitzer surge model. Chinese patent "CN111536069A" discloses a single-stage centrifugal compressor system using a flow sensor and a temperature and pressure sensor, and formulates different strategies according to the margin of the actual operating point from the anti-surge line. Chinese patent "CN117927496B" discloses an outlet quality control method using a mass flow meter, and when the surge impact value is greater than a preset value, the surge prevention valve is directly opened. Chinese patent "CN114198921 B" discloses a surge adjustment scheme for a static pressure air suspension centrifugal compressor, wherein the air supply scheme of the air suspension compressor is adjusted, which can ensure the stability of the air supply while reducing the possibility of surge in the air suspension compressor. Chinese patent "CN215370159U" discloses a two-stage compression centrifugal compressor refrigeration system, in which a vibration sensor and a current sensor are used to detect whether surge occurs, and an air supply and air release valve are used to intervene in surge.

[0006] However, the surge monitoring methods in the prior art are mainly based on predictions using the surge model of ordinary centrifugal compressors, using monitoring data from flow sensors, vibration sensors, and temperature and pressure sensors to determine the occurrence of surge, or adjusting the air supply scheme for static pressure air suspension compressors to regulate surge. These monitoring methods require the addition of additional sensors and are difficult to accurately monitor when the computer room air conditioning system is performing uninterrupted cooling throughout the year. Summary of the invention

[0007] In order to at least partially solve the above problems in the prior art, the present invention proposes a computer room air conditioning refrigeration system based on an air-floating centrifugal compressor, comprising:

[0008] an air-floating centrifugal compressor configured to compress a refrigerant;

[0009] a condenser disposed outside the machine room, a first end of the condenser connected to the exhaust end of the air-floating centrifugal compressor, and a second end of the condenser connected to the economizer, wherein the condenser is configured to cool the refrigerant;

[0010] an economizer having a first end connected to the condenser and a second end of the economizer connected to the evaporator, wherein the economizer is configured to subcool the refrigerant;

[0011] an evaporator disposed inside the machine room, a first end of the evaporator being connected to the economizer, and a second end of the evaporator being connected to an air inlet end of the air-floating centrifugal compressor, wherein the evaporator is configured to evaporate the refrigerant to absorb heat in the machine room; and

[0012] A compressor driver is connected to the air-floating centrifugal compressor, and the compressor driver is configured to collect status information of the air-floating centrifugal compressor and perform surge monitoring on the air-floating centrifugal compressor according to the status information.

[0013] In one embodiment of the present invention, it is provided that the air-floating centrifugal compressor comprises:

[0014] a first impeller configured to perform a first stage of pressurizing the refrigerant;

[0015] a second impeller configured to perform a second stage of pressurizing the refrigerant; and

[0016] The intermediate air supply port is arranged between the first impeller and the second impeller.

[0017] In one embodiment of the present invention, a main pipeline and an auxiliary pipeline are provided between the economizer and the evaporator, wherein a first portion of the refrigerant flowing out from the second end of the economizer flows toward the evaporator along the main pipeline, and a second portion re-enters the economizer along the auxiliary pipeline.

[0018] In one embodiment of the present invention, it is provided that the third end of the evaporator is connected to the auxiliary pipeline, and the fourth end of the evaporator is connected to the middle air supply port of the air-floating centrifugal compressor.

[0019] In one embodiment of the present invention, it is provided that the machine room air conditioning refrigeration system of the air-floating centrifugal compressor further comprises:

[0020] an electronic expansion valve arranged on the main pipe; and / or

[0021] The economizer expansion valve is arranged on the auxiliary pipeline.

[0022] In one embodiment of the present invention, it is provided that the computer room air conditioning refrigeration system based on the air floating centrifugal compressor further includes:

[0023] A hot gas bypass pipeline connects the exhaust end of the air-floating centrifugal compressor with the first end of the evaporator, wherein a hot gas bypass valve is provided on the hot gas bypass pipeline.

[0024] In one embodiment of the present invention, it is provided that the computer room air conditioning refrigeration system based on the air floating centrifugal compressor further includes:

[0025] A system main controller is connected to the air-floating centrifugal compressor, the fan of the condenser, the fan of the evaporator, the hot gas bypass valve, the electronic expansion valve and the economizer expansion valve, wherein the system main controller is configured to control the system to perform refrigeration, and when the compressor driver detects that the air-floating centrifugal compressor is surging, the control system performs a surge relief action.

[0026] In one embodiment of the present invention, collecting the status information of the air-floating centrifugal compressor and performing surge monitoring on the air-floating centrifugal compressor according to the status information includes:

[0027] Collecting status information of the air-floating centrifugal compressor, wherein the status information includes the rotation speed and power of the air-floating centrifugal compressor, wherein the interval for collecting information is once per second, and n groups of data are collected in each sampling period T1;

[0028] Perform a speed steady-state judgment, including: recording n groups of speed values ​​v1, v2, v3...vn within a sampling period T1; taking the maximum speed value vmax=MAX(v1, v2, v3...vn) and the minimum speed value vmin=MIN(v1, v2, v3...vn) of the n groups of speed values; performing a steady-state judgment on the speed, when vmax-vmin<speed steady judgment critical value △v, it is judged that the air-floating centrifugal compressor is at a stable speed during the T1 period, and a power fluctuation judgment is performed; and when vmax-vmin≥speed steady judgment critical value △v, it is judged that the air-floating centrifugal compressor is dynamically adjusting the speed, and no power fluctuation judgment is performed;

[0029] Performing power fluctuation judgment, including: recording n groups of power values ​​p1, p2, p3...pn within a sampling period T1; taking the maximum power value pmax=MAX(p1, p2, p3...pn) of the n groups of power values ​​and the minimum power value pmin=MIN(p1, p2, p3...pn) of the n groups of power values; and performing power fluctuation judgment, when [pmax-pmin] / [pmax+pmin]>10%, recording that the air-floating centrifugal compressor has power fluctuation; and

[0030] A surge judgment is performed, which includes: when power fluctuation occurs, the counter counts +1, and the surge confirmation countdown T2 is started; a speed steady-state judgment and a power fluctuation judgment are performed in each sampling period within the T2 period, wherein within the T2 period, when it is judged that power fluctuation occurs, the counter counts +1, and when it is judged that power fluctuation does not occur, the counter counts -1; when the count of the counter reaches a set number of times N, it is judged that the air-floating centrifugal compressor has surged, and the counter is cleared; when the count of the counter within the T2 period does not reach the set number of times N, it is judged that the air-floating centrifugal compressor has not surged, and the next surge judgment count is performed on the basis that the counter is not cleared.

[0031] In one embodiment of the present invention, when the compressor driver detects that the air-floating centrifugal compressor is surging, causing the control system to perform a surge relief action includes:

[0032] Increasing the operating frequency of the air-floating centrifugal compressor and the rotation speed of the condenser; and

[0033] When the frequency of the air-floating centrifugal compressor and / or the fan speed of the condenser rise to the maximum value and the surge has not yet recovered, the hot gas bypass valve is opened.

[0034] The present invention also proposes a surge monitoring method for a computer room air conditioning refrigeration system based on an air-floating centrifugal compressor, comprising the following steps:

[0035] Collecting status information of the air-floating centrifugal compressor, wherein the status information includes the rotation speed and power of the air-floating centrifugal compressor, wherein the interval for collecting information is once per second, and n groups of data are collected in each sampling period T1;

[0036] Perform a speed steady-state judgment, including: recording n groups of speed values ​​v1, v2, v3...vn within a sampling period T1; taking the maximum speed value vmax=MAX(v1, v2, v3...vn) and the minimum speed value vmin=MIN(v1, v2, v3...vn) of the n groups of speed values; performing a steady-state judgment on the speed, when vmax-vmin<speed steady judgment critical value △v, it is judged that the air-floating centrifugal compressor is at a stable speed during the T1 period, and a power fluctuation judgment is performed; and when vmax-vmin≥speed steady judgment critical value △v, it is judged that the air-floating centrifugal compressor is dynamically adjusting the speed, and no power fluctuation judgment is performed;

[0037] Performing power fluctuation judgment, including: recording n groups of power values ​​p1, p2, p3...pn within a sampling period T1; taking the maximum power value pmax=MAX(p1, p2, p3...pn) of the n groups of power values ​​and the minimum power value pmin=MIN(p1, p2, p3...pn) of the n groups of power values; and performing power fluctuation judgment, when [pmax-pmin] / [pmax+pmin]>10%, recording that the air-floating centrifugal compressor has power fluctuation; and

[0038] A surge judgment is performed, which includes: when power fluctuation occurs, the counter counts +1, and the surge confirmation countdown T2 is started; a speed steady-state judgment and a power fluctuation judgment are performed in each sampling period within the T2 period, wherein within the T2 period, when it is judged that power fluctuation occurs, the counter counts +1, and when it is judged that power fluctuation does not occur, the counter counts -1; when the count of the counter reaches a set number of times N, it is judged that the air-floating centrifugal compressor has surged, and the counter is cleared; when the count of the counter within the T2 period does not reach the set number of times N, it is judged that the air-floating centrifugal compressor has not surged, and the next surge judgment count is performed on the basis that the counter is not cleared.

[0039] The present invention has at least the following beneficial effects:

[0040] (1) The present invention adopts a dynamic pressure high-speed air-floating centrifugal compressor to replace a scroll compressor and is applied to the field of computer room air conditioning. The dynamic pressure high-speed air-floating centrifugal compressor is used as the power source of the refrigerant circuit. The unit has a longer life, better energy efficiency, and an oil-free system that is easier to maintain and use.

[0041] (2) The computer room air conditioning refrigeration system adopts a high-speed air-floating centrifugal compression stage as a two-stage compression, and adopts an intermediate air supply scheme to increase enthalpy and reduce consumption, further improving the system's cooling capacity and improving the system's cooling efficiency.

[0042] (3) The ultra-high-speed air-suspended centrifugal compressor of this refrigeration system can increase the speed from 0rpm to 150,000rpm within 5 seconds, and the refrigeration output response rate is fast. The air-suspended centrifugal compressor is designed for full symmetrical movement, and the refrigerant is driven by the centrifugal force of the impeller, with low vibration and low risk of refrigerant leakage.

[0043] (4) When the air conditioning system in the computer room provides continuous cooling throughout the year, the air-floating centrifugal compressor operates in a partial load regulation state. The control method claimed in this patent reduces the possibility of surge in the air-floating centrifugal compressor, broadens the application range of the air conditioner, and maintains a wide cooling capacity regulation range.

[0044] (5) Compared with the prior art, the method for monitoring the surge of an air-floating centrifugal compressor of the present invention does not require devices such as flow sensors. Instead, the inherent controller of the air-floating centrifugal compressor is used to collect two parameters, speed and power, and to determine whether there is surge through logic, so that the control is more accurate, reliable and fast.

[0045] (6) In this aspect, the anti-surge solution after the centrifugal compressor surges gives priority to increasing the speed of the compressor and condenser fan, so that the cooling capacity of the refrigeration system increases instead of decreases, which is more conducive to the control of the room temperature. After the centrifugal compressor and condenser fan reach the maximum speed, the hot gas bypass valve is proportionally controlled to remove the surge, thereby extending the duration of refrigeration to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] To further illustrate the advantages and features of various embodiments of the present invention, a more detailed description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.

[0047] Figure 1 A schematic structural diagram of a machine room air conditioning refrigeration system based on an air-floating centrifugal compressor in one embodiment of the present invention is shown.

[0048] Figure 2 A schematic diagram of the anti-surge principle of an air-floating centrifugal compressor in one embodiment of the present invention is shown.

[0049] Figure 3 A flow chart of a method for monitoring surge of a computer room air conditioning refrigeration system in an embodiment of the present invention is shown.

[0050] Figure 4 A schematic diagram of a process of performing a breath-release action in an embodiment of the present invention is shown.

[0051] Explanation of reference numerals: air-floating centrifugal compressor 101 , condenser 102 , economizer 103 , economizer expansion valve 104 , electronic expansion valve 105 , evaporator 106 , hot gas bypass valve 107 , system main controller 108 , compressor driver 109 . DETAILED DESCRIPTION

[0052] It should be noted that the components in the figures may be shown exaggeratedly for the sake of illustration and are not necessarily true to scale. In the figures, identical or functionally identical components are provided with the same reference numerals.

[0053] In the present invention, unless otherwise specified, "arranged on...", "arranged above..." and "arranged above..." do not exclude the existence of an intermediate between the two. In addition, "arranged on or above..." merely indicates the relative positional relationship between two components, and in certain cases, such as after reversing the product direction, it can also be converted into "arranged below or below...", and vice versa.

[0054] In the present invention, each embodiment is only intended to illustrate the aspects of the present invention and should not be construed as limiting.

[0055] In the present invention, unless otherwise specified, the quantifiers "a", "an" and "an" do not exclude the presence of a plurality of elements.

[0056] It should also be noted that in the embodiments of the present invention, for the sake of clarity and simplicity, only a portion of the parts or components may be shown, but those of ordinary skill in the art will understand that under the teachings of the present invention, the required parts or components may be added according to the needs of the specific scenario. In addition, unless otherwise specified, the features in different embodiments of the present invention may be combined with each other. For example, a feature in the second embodiment may be used to replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment also falls within the disclosure scope or recorded scope of the present application.

[0057] It should also be noted that within the scope of the present invention, the terms "same", "equal", "equal to" and the like do not mean that the values ​​of the two are absolutely equal, but allow a certain reasonable error, that is, the terms also cover "substantially the same", "substantially equal", "substantially equal to". By analogy, in the present invention, the terms "perpendicular to", "parallel to" and the like indicating directions also cover the meanings of "substantially perpendicular to" and "substantially parallel to".

[0058] In the present application, the term "configuration" refers to the setting of the shape, structure, material and / or function of the target object to achieve the desired technical effect, wherein "configuration" includes a variety of alternative technical means for achieving the technical effect, which become obvious under the teaching of the present application.

[0059] In addition, the numbering of the steps of the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps can be executed in different orders.

[0060] The present invention will be further described below in conjunction with specific embodiments with reference to the accompanying drawings.

[0061] In a first aspect of the present invention, an air-floating centrifugal compressor is used in place of a conventional scroll compressor in a computer room air conditioning refrigeration system. Figure 1FIG. 1 shows a schematic diagram of a machine room air conditioning refrigeration system based on an air-floating centrifugal compressor in one embodiment of the present invention. Figure 1 As shown, the system includes an air-floating centrifugal compressor 101 , a condenser 102 , an economizer 103 , an economizer expansion valve 104 , an electronic expansion valve 105 , an evaporator 106 , a hot gas bypass valve 107 , a system main controller 108 and a compressor driver 109 .

[0062] In some embodiments, the exhaust end of the air-floating centrifugal compressor 101 is connected to the condenser 102 through a copper tube, and the air intake end of the air-floating centrifugal compressor 101 is connected to the economizer 103 and the evaporator 106 through a copper tube.

[0063] In some embodiments, a hot gas bypass pipe is further provided at the exhaust end of the air-floating centrifugal compressor 101, wherein the air-floating centrifugal compressor 101 is connected to the inlet end of the evaporator 106 through the hot gas bypass pipe, and the hot gas bypass valve 107 is provided on the hot gas bypass pipe.

[0064] In some embodiments, the air-floating centrifugal compressor 101 is a two-stage compressor of a dynamic pressure type air-floating centrifugal compressor, wherein an intermediate air supply port is provided between the first-stage impeller and the second-stage impeller.

[0065] In some embodiments, the economizer 103 has a main circuit and an auxiliary circuit. The main circuit is connected to the condenser 102 and the electronic expansion valve 105 through a copper tube, and the electronic expansion valve 105 is connected to the evaporator 106 through a copper tube. An auxiliary circuit expansion valve is provided in the auxiliary circuit, and the outlet of the auxiliary circuit is connected to the middle air supply port of the air-floating centrifugal compressor 101.

[0066] In some embodiments, the system main controller 108 is connected to the fan of the evaporator 106, the fan of the condenser 102, the electronic expansion valve 105, the economizer expansion valve 104, the hot gas bypass valve 107 and the compressor driver 109 via cables, and the compressor driver 109 is connected to the air-floating centrifugal compressor 101 via cables.

[0067] In some embodiments, the system's jet reheat refrigeration cycle includes a main circulation loop and an auxiliary circulation loop. In the main circulation loop, the refrigerant passes through the condenser 102, the economizer 103, the evaporator 106, the air-floating centrifugal compressor 101 and the condenser 102 in sequence. In the auxiliary circulation loop, the refrigerant passes through the condenser 102, the economizer 103, the economizer expansion valve 104, the air-floating centrifugal compressor 101 and the condenser 102 in sequence.

[0068] In the main circulation loop, the high-temperature and high-pressure liquid refrigerant flowing out of the condenser 102 first passes through the economizer 103, and further the refrigerant passes through the electronic expansion valve 105 and enters the evaporator 106 for refrigeration, and the low-temperature and low-pressure gas flowing out of the evaporator 106 directly enters the air inlet end of the air-floating centrifugal compressor 101.

[0069] In the auxiliary circulation loop, the liquid refrigerant enters the economizer 103 again after passing through the economizer expansion valve 104, and on the one hand cools the refrigerant in the main circulation loop to increase its subcooling degree, and on the other hand evaporates into intermediate pressure superheated steam and flows into the intermediate air supply inlet of the air-floating centrifugal compressor 101. Due to the use of the jet enthalpy increase cycle, on the one hand, the subcooling degree of the refrigerant is improved, so that the evaporation enthalpy difference is increased, and the refrigeration capacity of the system is increased. On the other hand, the method of intermediate air supply to the air-floating centrifugal compressor increases the circulation volume of the system refrigerant and improves the refrigeration efficiency.

[0070] In some embodiments, the cable between the compressor driver 109 and the air-floating centrifugal compressor 101 includes a DC500V power cable and a CAN communication cable, wherein the power cable is used to provide power to the air-floating centrifugal compressor 101, and the CAN communication cable is used to provide a speed signal to the air-floating centrifugal compressor 101, and to feed back state information (such as current, power, temperature, speed, etc.) of the air-floating centrifugal compressor 101 from the air-floating centrifugal compressor 101. The compressor driver 109 performs big data analysis on the operating state of the air-floating centrifugal compressor 101 based on the state information, so as to monitor and determine whether the air-floating centrifugal compressor 101 is surging without the aid of additional hardware such as flow sensors, pressure sensors, and temperature sensors.

[0071] In some embodiments, the system main controller 108 is connected to each sub-actuator of the system through a cable, and the sub-actuator includes the fan of the condenser 102, the fan of the evaporator 106, the hot gas bypass valve 107, the electronic expansion valve 105, and the economizer expansion valve 103. When the system is in a normal refrigeration state, the system main controller 108 controls the fan of the condenser 102 so that it can be automatically controlled according to the outdoor temperature or the system high pressure to maintain the refrigeration system in an energy-efficient and high-efficiency range. Further, the system main controller 108 controls the fan of the evaporator 106 according to the return air temperature or the supply and return air temperature difference to maintain the machine room within a suitable temperature and humidity range. In addition, the system main controller 108 can also control the opening of the electronic expansion valve 105 to supply a suitable flow to the evaporator 106 and the economizer 103.

[0072] Since the air-floating centrifugal compressor-based machine room air conditioning refrigeration system maintains a year-round cooling state, and the evaporator 106 is placed in the machine room environment, and the condenser 102 is placed in the outdoor environment, the condensing pressure and the system compression ratio will change with the change of the outdoor ambient temperature, which is high in winter and low in summer. Therefore, when the system operates at a low refrigerant circulation flow, the air-floating centrifugal compressor 101 may surge.

[0073] Figure 2 FIG. 2 shows a schematic diagram of an air-floating centrifugal compressor anti-surge principle in one embodiment of the present invention. Figure 2 As shown, a represents the surge line of the centrifugal compressor. The centrifugal compressor surges above and to the left of the surge line. b represents the compressor surge operating point as a diagram. b' represents the operating point after de-surge as a diagram. A and B represent the de-surge action and the direction of driving the compressor operating point. n represents the compressor speed line. n1, n2, n3, n4, and n5 represent different directions of the centrifugal compressor. The horizontal axis represents the mass flow rate of the centrifugal compressor. The vertical axis represents the pressure ratio Pr of the compressor, where the pressure ratio Pr = high pressure PD / low pressure PS. Surge is an abnormal vibration that occurs in the centrifugal compressor when the flow rate is reduced to a certain level. The refrigerant in the fluid machinery and its pipelines undergoes periodic oscillations. It is a mechanical vibration caused by the excitation of the refrigerant by periodic suction and discharge. Surge will destroy the flow regularity of the refrigerant inside the compressor, generate mechanical noise, cause strong vibration of the working parts, and accelerate the damage of bearings and seals. Once surge causes resonance in the pipelines and foundation of the refrigeration unit, it will also cause serious consequences. From Figure 2 It can be seen that the compressor out-of-gassing measures are action A, that is, increasing the mass flow of the compressor when the compression ratio does not change, that is, increasing the speed of the compressor; the second is action B, that is, reducing the compression ratio, that is, increasing the speed of the condenser fan; or these two actions can be taken at the same time. This aspect proposes a treatment measure based on the characteristics that the centrifugal compressor in the computer room air conditioning system runs at partial load most of the time, and the compressor speed and condenser fan have adjustable amounts.

[0074] Figure 3 FIG. 2 is a flow chart of a method for monitoring surge of a computer room air conditioning refrigeration system in accordance with an embodiment of the present invention. Figure 3 As shown, the method can perform surge monitoring through the surge monitoring system inside the compressor driver 109. The steps of the surge monitoring method are described in detail below in conjunction with the system.

[0075] The surge monitoring system includes a speed and power acquisition module, a speed steady state determination module, a power fluctuation determination module and a surge determination module. The system can calculate and determine whether the air-floating centrifugal compressor 101 has surged based on the state information and analysis results collected by the compressor driver 109.

[0076] In the speed and power acquisition module, the speed and power data of the air floating centrifugal compressor 101 can be collected, wherein the data collection time can be set, for example, the data collection interval can be once per second, and a total of n groups of data are collected in one sampling period T1.

[0077] In the speed steady-state judgment module, n groups of speed values ​​v1, v2, v3...vn within a sampling period T1 can be recorded, and the maximum speed value vmax=MAX(v1, v2, v3...vn) and the minimum speed value vmin=MIN(v1, v2, v3...vn) are taken for the n groups of speed values. Further, a steady-state judgment is made on the speed. When vmax-vmin<speed steady-state judgment critical value △v, it is judged that the centrifugal compressor is at a stable speed during the T1 period, and a power fluctuation judgment is further made. When vmax-vmin≥speed steady-state judgment critical value △v, it is considered that the compressor is dynamically adjusting the speed, and no power fluctuation judgment is made.

[0078] In the power fluctuation determination module, n groups of power values ​​p1, p2, p3...pn within a sampling period T1 can be recorded, and the maximum power value pmax=MAX(p1, p2, p3...pn) and the minimum power value pmin=MIN(p1, p2, p3...pn) are taken for the n groups of power values. Further power fluctuation determination is performed, and if [pmax-pmin] / [pmax+pmin]>10%, a power fluctuation is recorded.

[0079] In the surge judgment module, when the power fluctuation judgment module judges that power fluctuation occurs, the counter executes action A to count +1, and starts the surge confirmation countdown T2, and performs speed steady-state judgment and power fluctuation judgment in each sampling period within the T2 period. Within the T2 period, when it is judged that power fluctuation occurs, the counter executes action A to count +1, and when it is judged that power fluctuation does not occur, the counter executes action B to count -1.

[0080] If the count of the counter reaches the set number of times N, it is determined that the air-floating centrifugal compressor 101 is surging, and the counter is reset. If the count of the counter does not reach the set number of times N within the surge confirmation countdown T2, it is determined that the air-floating centrifugal compressor 101 is not surging, and the counter is not reset at this time, and the next surge monitoring count is performed based on the current count that is not reset. In the counter, the minimum value of the counter is zero.

[0081] In some embodiments, the surge confirmation countdown time T2 ≥ 6*sampling period T1, sampling period T1 ≥ 30 seconds, number of data collection groups n ≥ 30, speed stability judgment critical value △v ≥ 2000rpm, and surge setting number N ≥ 5.

[0082] When the surge monitoring system detects and determines that the air-floating centrifugal compressor 101 surges, the compressor driver 109 sends the surge information to the system main controller 108, and the system main controller 108 controls the computer room air conditioning refrigeration system to perform a surge prevention action.

[0083] Figure 4 FIG. 2 shows a schematic diagram of a process for performing a breath-release action in one embodiment of the present invention. Figure 4 As shown, the degassing action includes increasing the operating frequency of the air-floating centrifugal compressor 101 and the speed of the external fan (i.e., the fan of the condenser 102), wherein the air-floating centrifugal compressor 101 increases the frequency at a speed of 1000rpm / s, and the fan of the condenser 102 increases the speed at a speed of 50rpm / s.

[0084] If surge is recovered during the frequency increase process, the air-floating centrifugal compressor 101 and the fan of the condenser 102 are automatically re-adjusted at the current value. If the frequency of the air-floating centrifugal compressor 101 and / or the fan speed of the condenser 102 are increased to the maximum value, and the surge has not been recovered, the hot gas bypass valve 107 is opened at this time to allow the high-pressure exhaust gas of the air-floating centrifugal compressor 101 to quickly enter the air inlet end of the evaporator 106, so that the condensing pressure PD drops rapidly, the evaporating pressure PS increases rapidly, and the compression ratio Pr also decreases rapidly. According to Figure 2 It can be seen that at this time, the working point will move rapidly downward and to the right along the centrifugal compressor speed line and leave the surge zone. Since the high and low pressure ends are partially connected at this time, the refrigeration capacity will be partially attenuated. In order to reduce the loss of refrigeration capacity, the opening ratio of the hot gas bypass valve 107 can be accurately controlled according to the calibration of the speed and pressure ratio of the air-floating centrifugal compressor 101.

[0085] In general, the present invention discloses a computer room air conditioning refrigeration system based on an air-floating centrifugal compressor. Compared with the traditional computer room air conditioning refrigeration system, the refrigeration system uses a two-stage compression air-floating centrifugal compressor 101 with intermediate air replenishment. The main circuit refrigerant cycle is that the air-floating centrifugal compressor 101 is exhausted to the condenser 102, and the liquid refrigerant is further supercooled through the economizer 103, and enters the evaporator 106 to cool the computer room after expansion and pressure reduction of the main electronic expansion valve 105, and then the superheated steam enters the primary air intake end of the air-floating centrifugal compressor 101. The auxiliary circuit refrigerant cycle is that a part of the refrigerant is diverted through the economizer 103, and after heat exchange with the economizer 103, it is sucked into the intermediate compression air intake end of the air-floating centrifugal compressor 101, mixed with the high-temperature and high-pressure refrigerant gas that has entered the primary air intake end of the air-floating centrifugal compressor 101 and compressed at the primary level, and a mixture with higher pressure and temperature is formed after secondary compression to complete the subsequent refrigeration cycle.

[0086] Compared with the traditional scroll compressor refrigeration system, the comprehensive energy efficiency of the machine room air conditioning refrigeration system based on the air floating centrifugal compressor proposed by the present invention can be effectively improved by 30%, which is due to the higher energy efficiency of the air floating centrifugal compressor, the high heat exchange efficiency of the system without lubricating oil, the higher mechanical structure efficiency of the centrifugal compressor compared with the scroll compressor, and the capacity and efficiency improvement brought by the intermediate air supply enthalpy increase. After the air floating centrifugal compressor 101 detected by the machine room air conditioning refrigeration system based on the air floating centrifugal compressor surges, the system main controller 108 preferentially controls the air floating centrifugal compressor 101 and the fan of the condenser 102 to speed up, so that the speed of the air floating centrifugal compressor 101 increases, the pressure ratio decreases, and quickly leaves the surge line. If it is still in the surge state at this time, the system main controller 108 controls the opening of the hot gas bypass valve 107 to physically solve the surge of the air floating centrifugal compressor 101 by sacrificing part of the cooling capacity.

[0087] Although various embodiments of the present invention are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the attached claims and their equivalents.

Claims

1. A machine room air conditioning refrigeration system based on an air floating centrifugal compressor, characterized in that: include: an air-floating centrifugal compressor configured to compress a refrigerant; a condenser disposed outside the machine room, a first end of the condenser connected to the exhaust end of the air-floating centrifugal compressor, and a second end of the condenser connected to the economizer, wherein the condenser is configured to cool the refrigerant; an economizer having a first end connected to the condenser and a second end of the economizer connected to the evaporator, wherein the economizer is configured to subcool the refrigerant; an evaporator disposed inside the machine room, a first end of the evaporator being connected to the economizer, and a second end of the evaporator being connected to an air inlet end of the air-floating centrifugal compressor, wherein the evaporator is configured to evaporate the refrigerant to absorb heat in the machine room; as well as A compressor driver is connected to the air-floating centrifugal compressor, and the compressor driver is configured to collect status information of the air-floating centrifugal compressor and perform surge monitoring on the air-floating centrifugal compressor according to the status information.

2. The machine room air conditioning refrigeration system based on air floating centrifugal compressor according to claim 1 is characterized in that: The air-floating centrifugal compressor comprises: a first impeller configured to perform a first stage of pressurizing the refrigerant; a second impeller configured to perform a second stage of pressurizing the refrigerant; and The intermediate air supply port is arranged between the first impeller and the second impeller.

3. The machine room air conditioning refrigeration system based on the air floating centrifugal compressor according to claim 2 is characterized in that: A main pipeline and an auxiliary pipeline are provided between the economizer and the evaporator, wherein a first portion of the refrigerant flowing out from the second end of the economizer flows toward the evaporator along the main pipeline, and a second portion reenters the economizer along the auxiliary pipeline.

4. The machine room air conditioning refrigeration system of the air floating centrifugal compressor according to claim 3, characterized in that: The third end of the evaporator is connected to the auxiliary pipeline, and the fourth end of the evaporator is connected to the middle air supply port of the air-floating centrifugal compressor.

5. The machine room air conditioning refrigeration system of the air floating centrifugal compressor according to claim 3, characterized in that: Also includes: An electronic expansion valve is arranged on the main pipe; and / or The economizer expansion valve is arranged on the auxiliary pipeline.

6. The machine room air conditioning refrigeration system based on air floating centrifugal compressor according to claim 1, characterized in that: Also includes: A hot gas bypass pipeline connects the exhaust end of the air-floating centrifugal compressor with the first end of the evaporator, wherein a hot gas bypass valve is provided on the hot gas bypass pipeline.

7. The computer room air conditioning refrigeration system based on an air floating centrifugal compressor according to any one of claims 1 to 6, characterized in that: Also includes: A system main controller is connected to the air-floating centrifugal compressor, the fan of the condenser, the fan of the evaporator, the hot gas bypass valve, the electronic expansion valve and the economizer expansion valve, wherein the system main controller is configured to control the system to perform refrigeration, and when the compressor driver detects that the air-floating centrifugal compressor is surging, the control system performs a surge relief action.

8. The machine room air conditioning refrigeration system based on air floating centrifugal compressor according to claim 7, characterized in that: Collecting the state information of the air-floating centrifugal compressor and performing surge monitoring on the air-floating centrifugal compressor according to the state information includes: Collecting status information of the air-floating centrifugal compressor, wherein the status information includes the rotation speed and power of the air-floating centrifugal compressor, wherein the interval for collecting information is once per second, and n groups of data are collected in each sampling period T1; Perform a speed steady-state judgment, which includes: recording n groups of speed values ​​v1, v2, v3...vn within a sampling period T1; taking the maximum speed value vmax=MAX(v1, v2, v3...vn) and the minimum speed value vmin=MIN(v1, v2, v3...vn) of the n groups of speed values; performing a steady-state judgment on the speed, when vmax-vmin<speed steady judgment critical value △v, judging that the air-floating centrifugal compressor is at a stable speed during the T1 period, and performing a power fluctuation judgment; and when vmax-vmin≥speed steady judgment critical value △v, judging that the air-floating centrifugal compressor is dynamically adjusting the speed, and not performing a power fluctuation judgment; Performing power fluctuation judgment, including: recording n groups of power values ​​p1, p2, p3...pn within a sampling period T1; taking the maximum power value pmax=MAX(p1, p2, p3...pn) of the n groups of power values ​​and the minimum power value pmin=MIN(p1, p2, p3...pn) of the n groups of power values; and performing power fluctuation judgment, when [pmax-pmin] / [pmax+pmin]>10%, recording that the air-floating centrifugal compressor has power fluctuation; and A surge judgment is performed, which includes: when power fluctuation occurs, the counter counts +1, and the surge confirmation countdown T2 is started; a speed steady-state judgment and a power fluctuation judgment are performed in each sampling period within the T2 period, wherein within the T2 period, when it is judged that power fluctuation occurs, the counter counts +1, and when it is judged that power fluctuation does not occur, the counter counts -1; when the count of the counter reaches a set number of times N, it is judged that the air-floating centrifugal compressor has surged, and the counter is cleared; when the count of the counter within the T2 period does not reach the set number of times N, it is judged that the air-floating centrifugal compressor has not surged, and the next surge judgment count is performed on the basis that the counter is not cleared.

9. The machine room air conditioning refrigeration system based on air floating centrifugal compressor according to claim 8, characterized in that: When the compressor driver detects that the air-floating centrifugal compressor is surging, the control system performs a surge relief action including: Increasing the operating frequency of the air-floating centrifugal compressor and the rotation speed of the condenser; and When the frequency of the air-floating centrifugal compressor and / or the fan speed of the condenser rise to the maximum value and the surge has not yet recovered, the hot gas bypass valve is opened.

10. A method for monitoring surge of a computer room air conditioning refrigeration system based on an air-floating centrifugal compressor, characterized in that: The following steps are involved: Collecting status information of the air-floating centrifugal compressor, wherein the status information includes the rotation speed and power of the air-floating centrifugal compressor, wherein the interval for collecting information is once per second, and n groups of data are collected in each sampling period T1; Perform a speed steady-state judgment, which includes: recording n groups of speed values ​​v1, v2, v3...vn within a sampling period T1; taking the maximum speed value vmax=MAX(v1, v2, v3...vn) and the minimum speed value vmin=MIN(v1, v2, v3...vn) of the n groups of speed values; performing a steady-state judgment on the speed, when vmax-vmin<speed steady judgment critical value △v, judging that the air-floating centrifugal compressor is at a stable speed during the T1 period, and performing a power fluctuation judgment; and when vmax-vmin≥speed steady judgment critical value △v, judging that the air-floating centrifugal compressor is dynamically adjusting the speed, and not performing a power fluctuation judgment; Performing power fluctuation judgment, including: recording n groups of power values ​​p1, p2, p3...pn within a sampling period T1; taking the maximum power value pmax=MAX(p1, p2, p3...pn) of the n groups of power values ​​and the minimum power value pmin=MIN(p1, p2, p3...pn) of the n groups of power values; and performing power fluctuation judgment, when [pmax-pmin] / [pmax+pmin]>10%, recording that the air-floating centrifugal compressor has power fluctuation; and A surge judgment is performed, which includes: when power fluctuation occurs, the counter counts +1, and the surge confirmation countdown T2 is started; a speed steady-state judgment and a power fluctuation judgment are performed in each sampling period within the T2 period, wherein within the T2 period, when it is judged that power fluctuation occurs, the counter counts +1, and when it is judged that power fluctuation does not occur, the counter counts -1; when the count of the counter reaches a set number of times N, it is judged that the air-floating centrifugal compressor has surged, and the counter is cleared; when the count of the counter within the T2 period does not reach the set number of times N, it is judged that the air-floating centrifugal compressor has not surged, and the next surge judgment count is performed on the basis that the counter is not cleared.

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