Air conditioning system and control method thereof

Abstract

The application discloses an air conditioning system and a control method. The air conditioning system comprises a compressor and a control device. The compressor comprises a sliding valve, and one sliding position of the sliding valve corresponds to one content volume ratio of the compressor. The control device is configured to obtain a system volume ratio under a current working condition and a volume ratio correction value; obtain an optimal content volume ratio of the compressor; adjust the sliding position of the sliding valve; and obtain the volume ratio correction value through the following steps: setting a temporary volume ratio correction value and obtaining a performance coefficient of the air conditioning system corresponding to the temporary volume ratio correction value; gradually reducing the temporary volume ratio correction value by turns and obtaining the performance coefficient corresponding to the temporary volume ratio correction value until the performance coefficient obtained at the last time is less than the performance coefficient obtained at the previous time, and assigning the volume ratio correction value to the temporary volume ratio correction value obtained at the previous time. The application considers that the compressor is provided with an additional air inlet, the optimal content volume ratio is obtained by obtaining an optimized content volume ratio correction value, the sliding valve position is adjusted, and the compressor is operated at the best efficiency.

Description

Technical Field

[0001] This application relates to the field of air conditioning system control, and in particular to an air conditioning system and its control method. Background Technology

[0002] Screw compressors are common components in air conditioning systems. A screw compressor utilizes the meshing of the toothed volumes of a pair of screw rotors, creating changes in the volume of the basic unit space formed by the toothed spaces to complete the process of gas intake, compression, and discharge. Internal volume ratio V ic (V ic =V s / V d V is an important operating parameter of screw compressors. s V is the volume of the rotor intake chamber. d The rotor exhaust chamber volume V is the volume of the rotor exhaust chamber. The rotor exhaust chamber volume V can be adjusted by adjusting the position of the slide valve. d The size of V is adjusted to regulate the content volume ratio. ic . Summary of the Invention

[0003] Air conditioning systems have different system volume ratios under different operating conditions. Ideally, the internal volume ratio of the compressor should match the system volume ratio of the air conditioning system. The position of the slide valve should be adjusted using the system volume ratio of the air conditioning system as a parameter to ensure that the compressor rotor discharge chamber pressure is equal to the air conditioning system discharge pressure. This avoids the extra power consumption caused by over-compression or under-compression and ensures that the compressor operates at its optimal efficiency, that is, the ratio of system heat exchange to compressor current reaches its maximum.

[0004] In air conditioning refrigeration systems, an economizer is typically included. This economizer is fluidly connected to the compressor via a gas inlet on the compressor, allowing refrigerant from the economizer's outlet pipe to flow into the compressor for compression. This results in a higher discharge density and pressure compared to a compressor without a gas inlet. Compared to an air conditioning system without an economizer or with the economizer not operating, if the system operating conditions and the compressor's slide valve position remain unchanged, the increased intake volume will also increase the compressor's actual internal volume ratio due to the additional refrigerant entering the compressor via the gas inlet. In this case, if the compressor's slide valve position is adjusted directly using the system volume ratio as a parameter, the compressor will over-compress, leading to low compressor efficiency and increased vibration and noise.

[0005] Therefore, under a specific unit operating condition, to ensure the compressor operates at its optimal efficiency, it is necessary to obtain an optimized adjustment position of the compressor slide valve, that is, to obtain optimized slide valve position adjustment parameters to adjust the slide valve so that the actual internal volume ratio of the compressor equals the optimal internal volume ratio under that operating condition, thereby maximizing the overall performance of the unit. Specifically, this application uses a parameter approximation method to test the compressor's optimal operating efficiency, then reverse-engineers the volume ratio correction value for the compressor operating at its optimal efficiency, thus obtaining the compressor's optimal internal volume ratio under that operating condition. The slide valve position is then adjusted based on the compressor's optimal internal volume ratio, and finally, the obtained volume ratio correction value under that operating condition is stored in the control device for direct retrieval and use under the same operating conditions in the future.

[0006] Specifically, according to a first aspect of this application, an air conditioning system is provided, including a compressor and a control device. The compressor includes a slide valve having a plurality of sliding positions, one of which corresponds to a volume ratio of the compressor. The control device is configured under the operating condition to: acquire a volume ratio correction value under the operating condition; acquire an optimal volume ratio of the compressor based on the volume ratio correction value and the system volume ratio; and adjust the sliding position of the slide valve based on the optimal volume ratio of the compressor.

[0007] According to a first aspect of this application, the air conditioning system further includes: a plurality of sensors, the plurality of sensors determining the operating conditions and the system volume ratio.

[0008] According to a first aspect of this application, the air conditioning system further includes: an evaporator, the evaporator being fluidly connected to the compressor; wherein the plurality of sensors includes: an inlet water temperature sensor, an outlet water temperature sensor, and an ambient temperature sensor, the inlet water temperature sensor being used to detect the inlet water temperature of the evaporator, the outlet water temperature sensor being used to detect the outlet water temperature of the evaporator, and the ambient temperature sensor being used to detect the ambient temperature of the air conditioning system.

[0009] According to a first aspect of this application, the compressor further includes a screw, the control device is configured to acquire the rotational speed of the screw; and the control device determines the operating conditions by measuring the ambient temperature, the inlet water temperature, the outlet water temperature, and the rotational speed of the screw.

[0010] According to a first aspect of this application, the plurality of sensors further includes: a system intake pressure sensor for detecting the intake pressure of the air conditioning system; and a system exhaust pressure sensor for detecting the exhaust pressure of the air conditioning system, wherein the control device determines the system volume ratio by measuring the intake pressure and the exhaust pressure.

[0011] According to a first aspect of this application, the control device is further configured to acquire the current parameters of the compressor, and to acquire the performance coefficient of the air conditioning system based on the current parameters, the inlet water temperature, and the outlet water temperature, wherein the performance coefficient of the air conditioning system is maximized when the compressor is at the optimal internal volume ratio.

[0012] According to a first aspect of this application, the air conditioning system further includes: an economizer, the economizer being fluidly connected to the compressor; wherein when the economizer is in a closed state, the optimal volume ratio is equal to the system volume ratio.

[0013] According to a first aspect of this application, when the economizer is in the open state, it is determined whether the control device stores the volume ratio correction value corresponding to the operating condition.

[0014] According to a first aspect of this application, if the control device has stored the volume ratio correction value corresponding to the operating condition, the optimal internal volume ratio is obtained based on the volume ratio correction value and the system volume ratio, and the sliding position of the slide valve is adjusted based on the optimal internal volume ratio.

[0015] According to a first aspect of this application, if the control device does not store the volume ratio correction value corresponding to the operating condition, the volume ratio correction value is obtained through the following steps: First, a first temporary volume ratio correction value is set, and the sliding position of the slide valve is adjusted according to the first temporary volume ratio correction value. After the air conditioning system has been running for a period of time, the performance coefficient of the air conditioning system is obtained. Second, the first temporary volume ratio correction value is reduced to obtain a second temporary volume ratio correction value. The sliding position of the slide valve is adjusted according to the second temporary volume ratio correction value. After the air conditioning system has been running for a period of time, the performance coefficient of the air conditioning system is obtained, and the volume ratio correction value is assigned... The value is the first temporary volume ratio correction value; fourth step, if the unit performance coefficient obtained in the second step is less than the second temporary volume ratio correction value to obtain the third temporary volume ratio correction value, adjust the sliding position of the slide valve according to the third temporary volume ratio correction value, obtain the performance coefficient of the air conditioning system after the air conditioning system has been running for a period of time, and assign the volume ratio correction value to the second temporary volume ratio correction value; sixth step, if the unit performance coefficient obtained in the fourth step is less than the unit performance coefficient obtained in the previous step, repeat the fourth step until the unit performance coefficient obtained in the next step is less than the unit performance coefficient obtained in the previous step, and assign the volume ratio correction value to the temporary volume ratio correction value obtained in the previous step.

[0016] According to a first aspect of this application, the compressor further includes an intake port, a replenishment port, an exhaust port, and a slide valve displacement sensor, wherein the control device adjusts the sliding position of the slide valve through the slide valve displacement sensor, and wherein the economizer is connected to the compressor through the replenishment port.

[0017] According to a first aspect of this application, the air conditioning system further includes: an intake pipe, an exhaust pipe, a condenser, an economizer expansion valve, and a main expansion valve; the intake pipe is connected to the intake port of the compressor, wherein a system intake pressure sensor is disposed in the intake pipe; the evaporator is connected to the compressor via the intake pipe; the exhaust pipe is connected to the exhaust port of the compressor, wherein a system exhaust pressure sensor is disposed in the exhaust pipe; the condenser is connected to the compressor via the exhaust pipe, and the condenser is in fluid communication with the economizer; the economizer expansion valve is in fluid communication with the condenser and the economizer; and the main expansion valve is in fluid communication with the evaporator and the economizer.

[0018] According to a second aspect of this application, a control method is provided for controlling a compressor in an air conditioning system, the compressor including a slide valve, the air conditioning system including a control device, the control method comprising the following steps: determining the operating conditions and system volume ratio of the air conditioning system; obtaining a volume ratio correction value under the operating conditions; obtaining an optimal internal volume ratio of the compressor based on the volume ratio correction value and the system volume ratio; and adjusting the sliding position of the slide valve based on the optimal internal volume ratio of the compressor.

[0019] According to a second aspect of this application, the air conditioning system further includes: a plurality of sensors, through which the operating conditions of the air conditioning system and the system volume ratio are determined.

[0020] According to a second aspect of this application, the air conditioning system further includes: an evaporator, the evaporator being fluidly connected to the compressor; wherein the plurality of sensors include: an inlet water temperature sensor, an outlet water temperature sensor, and an ambient temperature sensor, the inlet water temperature sensor being used to detect the inlet water temperature of the evaporator; the outlet water temperature sensor being used to detect the outlet water temperature of the evaporator; and the ambient temperature sensor being used to detect the ambient temperature of the air conditioning system.

[0021] According to a second aspect of this application, the compressor further includes a screw, the control device is configured to acquire the rotational speed of the screw; and the control device determines the operating conditions by measuring the ambient temperature, the inlet water temperature, the outlet water temperature, and the rotational speed of the screw.

[0022] According to a second aspect of this application, the plurality of sensors further includes: a system intake pressure sensor for detecting the intake pressure of the air conditioning system; and a system exhaust pressure sensor for detecting the exhaust pressure of the air conditioning system, wherein the control device determines the system volume ratio by measuring the intake pressure and the exhaust pressure.

[0023] According to a second aspect of this application, the control device is further configured to acquire the current parameters of the compressor, and to acquire the performance coefficient of the air conditioning system based on the current parameters, the inlet water temperature, and the outlet water temperature, wherein the performance coefficient of the air conditioning system is maximized when the compressor is at the optimal internal volume ratio.

[0024] According to a second aspect of this application, the air conditioning system further includes an economizer, which is fluidly connected to the compressor; wherein when the economizer is in a closed state, the optimal volume ratio is equal to the system volume ratio.

[0025] According to a second aspect of this application, when the economizer is in the open state, it is determined whether the control device stores the volume ratio correction value corresponding to the operating condition.

[0026] According to a second aspect of this application, if the control device has stored the volume ratio correction value corresponding to the operating condition, the optimal internal volume ratio is obtained based on the volume ratio correction value and the system volume ratio, and the sliding position of the slide valve is adjusted based on the optimal internal volume ratio.

[0027] According to a second aspect of this application, if the control device does not store the volume ratio correction value corresponding to the operating condition, the volume ratio correction value is obtained through the following steps: First, a first temporary volume ratio correction value is set, and the sliding position of the slide valve is adjusted according to the first temporary volume ratio correction value. After the air conditioning system has been running for a period of time, the performance coefficient of the air conditioning system is obtained. Second, the first temporary volume ratio correction value is reduced to obtain a second temporary volume ratio correction value. The sliding position of the slide valve is adjusted according to the second temporary volume ratio correction value. After the air conditioning system has been running for a period of time, the performance coefficient of the air conditioning system is obtained, and the volume ratio correction value is assigned... The value is the first temporary volume ratio correction value; fourth step, if the unit performance coefficient obtained in the second step is less than the second temporary volume ratio correction value to obtain the third temporary volume ratio correction value, adjust the sliding position of the slide valve according to the third temporary volume ratio correction value, obtain the performance coefficient of the air conditioning system after the air conditioning system has been running for a period of time, and assign the volume ratio correction value to the second temporary volume ratio correction value; sixth step, if the unit performance coefficient obtained in the fourth step is less than the unit performance coefficient obtained in the previous step, repeat the fourth step until the unit performance coefficient obtained in the next step is less than the unit performance coefficient obtained in the previous step, and assign the volume ratio correction value to the temporary volume ratio correction value obtained in the previous step.

[0028] According to a second aspect of this application, the compressor further includes: an intake port, a replenishment port, an exhaust port, and a slide valve displacement sensor, wherein the control device adjusts the sliding position of the slide valve through the slide valve displacement sensor, and wherein the economizer is connected to the compressor through the replenishment port.

[0029] According to a second aspect of this application, the air conditioning system further includes: an intake pipe, an exhaust pipe, a condenser, an economizer expansion valve, and a main expansion valve; the intake pipe is connected to the intake port of the compressor, wherein a system intake pressure sensor is disposed in the intake pipe; the evaporator is connected to the compressor via the intake pipe; the exhaust pipe is connected to the exhaust port of the compressor, wherein a system exhaust pressure sensor is disposed in the exhaust pipe; the condenser is connected to the compressor via the exhaust pipe, and the condenser is in fluid communication with the economizer; the economizer expansion valve is in fluid communication with the condenser and the economizer; and the main expansion valve is in fluid communication with the evaporator and the economizer.

[0030] According to a third aspect of this application, a compressor is provided, wherein the compressor is any one of the compressors described in the first aspect of this application.

[0031] According to a fourth aspect of this application, a compressor is provided, which is regulated by the control method described in the second aspect of this application.

[0032] Other features, advantages, and embodiments of this application may be set forth or become apparent from the following detailed description, accompanying drawings, and claims. Furthermore, it should be understood that the above description and the following detailed description are exemplary and intended to provide further explanation, without limiting the scope of the claimed application. However, the detailed description and specific examples only indicate preferred embodiments of this application. Various changes and modifications within the spirit and scope of this application will become apparent to those skilled in the art through these detailed descriptions. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of an air conditioning system according to an embodiment of this application;

[0034] Figure 2 This is a schematic diagram of the compressor when the slide valve is in the first position.

[0035] Figure 3 This is a schematic diagram of the compressor when the slide valve is in the second position.

[0036] Figure 4A and Figure 4B A flowchart of the control method;

[0037] Figure 5 This is a schematic diagram illustrating the performance variation trend of the compressor unit under different internal volume ratios;

[0038] Figure 6 for Figure 1 The diagram shows the structural block diagram of the control device. Detailed Implementation

[0039] Various specific embodiments of this application will now be described with reference to the accompanying drawings, which form part of this specification. It should be understood that although terms indicating direction, such as "front," "rear," "up," "down," "left," and "right," are used herein to describe various exemplary structural parts and elements, their use is merely for illustrative purposes and is based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed herein can be arranged in different orientations, these terms indicating direction are illustrative only and should not be considered limiting.

[0040] Figure 1 A schematic diagram of the structure of the air conditioning system 100 according to this application is shown.

[0041] like Figure 1As shown, taking a refrigeration system as an example, the air conditioning system 100 of this application includes a compressor 102, a condenser 104, an economizer 106, an economizer expansion valve 108, a main expansion valve 110, and an evaporator 112 that are fluidly connected in sequence. The compressor 102 has an intake port 152, a make-up air port 154, and an exhaust port 156. The intake port 152 of the compressor 102 is fluidly connected to the evaporator 112 through an intake pipe 142. The make-up air port 154 of the compressor 102 is fluidly connected to the economizer 106 through a make-up air pipe 143. The exhaust port 156 of the compressor 102 is fluidly connected to the condenser 104 through an exhaust pipe 144. The condenser 104 is fluidly connected to the economizer 106 and the economizer expansion valve 108. The economizer 106 is fluidly connected to the main expansion valve 110. The main expansion valve 110 is fluidly connected to the evaporator 112.

[0042] The air conditioning system 100 exchanges heat with the water in the water pipe 140 at the evaporator 112, but the refrigerant in the evaporator 112 and the water in the water pipe 140 are in different pipes and are not fluidly connected to each other. The water pipe 140 includes an inlet pipe 146 and an outlet pipe 148. Ambient temperature water can flow through the inlet pipe 146 to the vicinity of the evaporator 112 to exchange heat.

[0043] The air conditioning system 100 also includes a system suction pressure sensor 122, a system discharge pressure sensor 124, an inlet water temperature sensor 126, and an outlet water temperature sensor 128. The system suction pressure sensor 122 is installed on the suction pipe 142 between the suction port 152 of the compressor 102 and the evaporator 112, and is used to detect the suction pressure P of the air conditioning system 100. s The system exhaust pressure sensor 124 is installed on the exhaust pipe 144 between the exhaust port 156 of the compressor 102 and the condenser 104, and is used to detect the exhaust pressure P of the air conditioning system 100. d By inhalation pressure P s and exhaust pressure P d The system volume ratio V of the air conditioning system 100 can be calculated. is The inlet water temperature sensor 126 is installed on the inlet water pipe 146 and is used to detect the inlet water temperature T of the evaporator 112. ew The outlet water temperature sensor 128 is installed on the outlet water pipe 148 and is used to detect the outlet water temperature T of the evaporator 112. lw .

[0044] Continue to refer to Figure 1The high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 156 of the compressor 102 enters the condenser 104, releasing heat to condense into a medium-temperature liquid refrigerant. A portion X of the medium-temperature liquid refrigerant flows to the economizer expansion valve 108, and another portion Y flows to the economizer 106. After the liquid refrigerant X is throttled and depressurized by the economizer expansion valve 108, it forms a low-temperature gas-liquid two-phase refrigerant X. The refrigerant X flowing out of the economizer expansion valve 108 flows to the economizer 106, where it exchanges heat with the medium-temperature liquid refrigerant Y flowing into the economizer 106. In the economizer 106, the medium-temperature liquid refrigerant Y and the low-temperature gas-liquid two-phase refrigerant X are fluidly isolated from each other and do not have fluid communication. After the heat exchange, the medium-temperature liquid refrigerant Y is further cooled and flows to the main expansion valve 110; the low-temperature gas-liquid two-phase refrigerant X evaporates into gaseous refrigerant X, returning to the compressor 102 through the compressor's gas fill port 154. The low-temperature liquid refrigerant Y, after being throttled and depressurized by the main expansion valve 110, forms a low-temperature gas-liquid two-phase refrigerant Y which enters the evaporator 112. In the evaporator 112, the low-temperature gas-liquid two-phase refrigerant Y exchanges heat with room-temperature water from the inlet pipe 146, absorbing heat from the water and evaporating into gaseous refrigerant Y. Finally, it returns to the compressor 102 through the suction port 152, completing the refrigerant circulation. The room-temperature water in the inlet pipe 146 exchanges heat with the low-temperature gas-liquid two-phase refrigerant Y in the evaporator 112, releasing heat to form low-temperature water, which flows out from the outlet pipe 148, completing the heat exchange between the water and the refrigerant.

[0045] The air conditioning system 100 also includes a control device 114, which is equipped with an ambient temperature sensor 130 for detecting the ambient temperature T of the air conditioning system 100 unit. e The system intake pressure sensor 122, system exhaust pressure sensor 124, inlet water temperature sensor 126, outlet water temperature sensor 128, and ambient temperature sensor 130 are respectively connected to the control device 114 for communication, and can transmit various detected parameters to the control device 114.

[0046] The control device 114 can adjust the position of the slide valve in real time according to the optimal internal volume ratio of the compressor 102, so that the rotor exhaust chamber pressure (i.e., internal pressure) of the compressor 102 matches the exhaust pressure (i.e., external pressure) of the air conditioning system, thereby avoiding over-compression or under-compression, improving the operating efficiency of the air conditioning system 100 and reducing energy consumption. Specifically, under a specific operating condition, the corrected internal volume ratio of the compressor is obtained by acquiring the volume ratio correction value pre-stored in the control device 114, which is the optimal internal volume ratio of the compressor 102 under the current operating condition. The slide valve position is adjusted according to this optimal internal volume ratio to maximize the operating efficiency of the air conditioning system 100. If the corresponding volume ratio correction value is not stored in the control device 114, it is necessary to pre-operate the air conditioning system 100 under optimal unit performance (the rotor exhaust chamber pressure of the compressor 102 is consistent with the exhaust pressure of the air conditioning system 100, and there is no over-compression or under-compression) to deduce the volume ratio correction value under this operating condition, thereby obtaining the optimal internal volume ratio of the compressor under this operating condition. The position of the slide valve is then adjusted according to the optimal internal volume ratio of the compressor. Finally, the obtained volume ratio correction value under this operating condition is stored in the control device 114 so that it can be directly retrieved and used under the same operating conditions in the future.

[0047] Figure 2-3 These are schematic diagrams of the compressor 102 when the slide valve 232 is in the first and second positions, respectively.

[0048] like Figure 2 and Figure 3 As shown, the compressor 102 includes an intake chamber 236, an exhaust chamber 237, and a compression chamber 231. The intake chamber 236 is fluidly connected to the intake pipe 142 via an intake port 152, and the exhaust chamber 237 is fluidly connected to the exhaust pipe 144 via an exhaust port 156. The compressor 102 also includes a screw (not shown). The compression chamber 231 is formed by the toothed grooves of a pair of screw rotors, and the compression chamber 231 is fluidly connected to the intake chamber 236 and the exhaust chamber 237. The gas supply port 154 is fluidly connected to the compression chamber 231. Thus, the refrigerant in the intake pipe 142 can enter the intake chamber 236 through the intake port 152 and then enter the compression chamber 231 for compression. The refrigerant in the gas supply pipe 143 can also flow into the compression chamber 231 through the gas supply port 154 for compression. After compression, both portions of refrigerant enter the exhaust chamber 237 together and are finally discharged into the exhaust pipe 144 through the exhaust port 156, completing the compression process of the compressor 102.

[0049] The compressor 100 also includes a slide valve 232, a drive device 233, and a slide valve displacement sensor 234. The drive device 233 is mechanically connected to the slide valve 232 to drive the slide valve 232 to move. In the embodiments of this application, the drive device 233 is a hydraulic drive device. For those skilled in the art, the drive device 233 can also be driven in other ways. The control device 114 is communicatively connected to the drive device 233 and the slide valve displacement sensor 234, respectively. Therefore, the control device 114 can detect the current position of the slide valve 232 through the slide valve displacement sensor 234 and drive the slide valve 232 to move to the target position by controlling the drive device 233.

[0050] The slide valve 232 has a first position corresponding to the minimum internal volume ratio of the compressor 102, and a second position corresponding to the maximum internal volume ratio of the compressor 102. Specifically, when the slide valve 232 moves to such a position... Figure 2 When shown in the leftmost position (i.e., the first position), the exhaust chamber 237 has the largest exhaust chamber volume, according to the compressor internal volume ratio formula: V ic =V s / V d (where V) ic V represents the internal volume ratio of the compressor. s V represents the volume of the rotor intake chamber. d (This refers to the rotor exhaust chamber volume), therefore the compressor has a minimum internal volume ratio. When slide valve 232 moves to... Figure 3 When the rightmost position (i.e., the second position) is shown, the exhaust chamber 237 has the smallest exhaust chamber volume. According to the compressor internal volume ratio formula above, the compressor has the largest internal volume ratio. The drive device 233 is used to control the movement of the slide valve 232 between the first and second positions to adjust the volume of the exhaust chamber 237, thereby adjusting the internal volume ratio V of the compressor 102. ic The slide valve displacement sensor 234 can detect the specific position of the slide valve 232 between the first position and the second position, and feed back the slide valve position to the control device 114, which in turn drives the slide valve 232 to move through the drive device 233.

[0051] Figure 4A and Figure 4B This is a flowchart of the control method for control device 114.

[0052] like Figure 4A As shown, the program begins at step 402.

[0053] At step 404, the control device 114 obtains the suction pressure P of the air intake pipe 142 of the air conditioning system unit through the system suction pressure sensor 122, the system exhaust pressure sensor 124, the inlet water temperature sensor 126, the outlet water temperature sensor 128, and the ambient temperature sensor 130, respectively.s The exhaust pressure P of exhaust pipe 144 d The inlet water temperature T of inlet pipe 146 ew The outlet water temperature T of water pipe 148 lw and ambient temperature T e The control device 114 can also detect the screw speed R of the compressor 102 and the current parameter I of the compressor 102. c And according to the inhalation pressure P s and exhaust pressure P d Calculate the system volume ratio V is The calculation formula is as follows:

[0054]

[0055] Where k is the adiabatic constant of the medium, which is related to the material of the refrigerant in the air conditioning refrigeration system. The adiabatic constants of some common refrigerants are shown in Table 1 below.

[0056] Refrigerant type R134a R513A R410A R22 R1234yf adiabatic constant of medium 0.85 0.86 0.78 0.79 0.87

[0057] Table 1. Adiabatic constants of common refrigerants

[0058] After step 404 is completed, the process proceeds to step 406.

[0059] At step 406, it is determined whether the economizer 106 of the air conditioning system 100 is turned on. If the economizer 106 is not turned on, the internal volume ratio of the compressor is adjusted to V. ic With system volume ratio V is This ensures that the compressor rotor discharge chamber pressure matches the air conditioning system discharge pressure, allowing the process to proceed. Figure 4B Step 430 in the process.

[0060] At step 430, the optimal internal volume ratio V of compressor 102 is achieved. ice With system volume ratio V is Since they are equal, the optimal internal volume ratio correction value δ of compressor 102 is directly applied. me The value is assigned to 1. After the operation in step 430 is completed, the process proceeds to step 432.

[0061] If the economizer 106 is open, the refrigerant discharged from the economizer 106 includes not only the refrigerant drawn in from the suction port 152 of the compressor 102, but also the refrigerant drawn in from the make-up port 154 of the compressor 102. Therefore, compared with a refrigeration system without the economizer, when the slide valve of the compressor 102 is in the same position, under the same system operating conditions and suction pressure, the volume of refrigerant discharged from the discharge port 156 of the compressor 102 remains unchanged, but its mass and density increase. This causes the rotor discharge chamber pressure of the compressor 102 to be greater than the discharge pressure of the air conditioning system 100, resulting in undesirable overcompression of the compressor 102. Consequently, the operating efficiency of the compressor 102 is low. Therefore, it is necessary to readjust the position of the slide valve of the compressor 102 to avoid adverse conditions. At this point, the process proceeds to step 408.

[0062] At step 408, the current operating condition is confirmed, specifically based on the inlet water temperature T obtained in step 404. ew Outlet water temperature T lw Ambient temperature T e The screw speed R is obtained by taking the current operating condition parameter m value from Table 2 below.

[0063]

[0064]

[0065] Table 2 Index of m values

[0066] The current operating condition parameter m is composed of 8 decimal digits. The first and second digits from right to left are the outlet water temperature parameter value minus 1, the third and fourth digits are the inlet water temperature parameter value minus 1, the fifth and sixth digits are the ambient temperature parameter value minus 1, and the seventh and eighth digits are the unit load parameter value minus 1.

[0067] After step 408 is completed, the process proceeds to step 410.

[0068] When the air conditioning system 100 is first run, the memory 606 of the control device 114 (see...) Figure 6 The volume ratio correction value δ corresponding to any operating condition parameter m is not stored in the system. m As the air conditioning system 100 operates repeatedly under different conditions, the control device 114 will successively acquire and store the volume ratio correction value δ under different operating conditions. m When the air conditioning system 100 encounters the same operating condition again, the control device 114 can directly retrieve the previously stored volume ratio correction value δ for that operating condition from the memory 606. m Then, the optimal internal volume ratio V of compressor 102 under this operating condition is calculated. ice To adjust the position of the slide valve.

[0069] Therefore, at step 410, it is necessary to determine whether the memory 606 has already stored the volume ratio correction value δ corresponding to the current operating condition parameter m value obtained in step 408. m If the memory 606 already stores the volume ratio correction value δ corresponding to the current operating condition parameter m value obtained in step 406. m The process then proceeds to Figure 4B Step 428 in the process.

[0070] In step 428, the optimal internal volume ratio correction value δ of compressor 102 is adjusted. me The value assigned is the volume ratio correction value δ corresponding to the current operating condition parameter m, which is already stored in memory 606. m After step 428 is completed, the process proceeds to step 432.

[0071] If the memory 606 does not store the volume ratio correction value δ corresponding to the current operating condition parameter m value obtained in step 408 m Then the process proceeds to step 412 to continue obtaining the volume ratio correction value δ corresponding to the current operating condition parameter m. m .

[0072] At step 412, set the initial temporary volume ratio correction value δ. m(j) And assign it the value 1.0, where j = 0, 1, 2, ..., n, for example δ m(0) =1.0. Based on the initial temporary volume ratio correction value δ m(j) Calculate the current internal volume ratio V of compressor 102. ic(j) The calculation formula is as follows:

[0073] V ic(j) =δ m(j) ×V is ,

[0074] After step 412 is completed, the process proceeds to step 414.

[0075] At step 414, based on the current internal volume ratio V of compressor 102 obtained in step 412... ic(j) Adjust the position of the slide valve. After completing step 414, the process proceeds to step 416.

[0076] At step 416, the air conditioning system 100 is kept running for 5 minutes at the slide valve position adjusted in step 414, and then the inlet water temperature T is obtained again. ew Outlet water temperature T lw And the current parameter I of compressor 102 c Calculate the current unit performance coefficient (COP). m(j) The calculation formula is as follows:

[0077]

[0078] After step 416 is completed, the process proceeds to step 418.

[0079] like Figure 4B At step 418, the initial temporary volume ratio correction value δ set in step 412 is adjusted. m(j) Subtracting 0.01 from the value yields the second temporary volume ratio correction value δ. m(j+1) For example, δ m(1) =δ m(0) -0.01. Based on the second temporary volume ratio correction value δ m(j+1) Calculate the current internal volume ratio V of compressor 102. ic(j+1) The calculation formula is as follows:

[0080] δ m(j+1) =δ m(j) -0.01,

[0081] V ic(j+1) =δ m(j+1) ×V is ,

[0082] After step 418 is completed, the process proceeds to step 420.

[0083] At step 420, based on the current internal volume ratio V of compressor 102 obtained in step 418... ic(j+1) Adjust the position of the slide valve. After completing step 420, the process proceeds to step 422.

[0084] At step 422, the air conditioning system 100 is kept running at the slide valve position adjusted in step 420 for 5 minutes, and then the inlet water temperature T is obtained again. ew Outlet water temperature T lw And the current parameter I of compressor 102 c Calculate the current unit performance coefficient (COP). m(j+1) .

[0085] After step 422 is completed, the process proceeds to step 424.

[0086] At step 424, the COP obtained in step 416 is compared. m(j) and the COP obtained in step 422 m(j+1) If COP m(j+1) Less than COP m(j) The process proceeds to step 426; if COP m(j+1) Greater than COP m(j) The process then proceeds to step 418, repeating steps 418 to 424 until the last obtained unit performance coefficient (COP) is obtained.m(j+1) Less than the previously obtained unit performance coefficient (COP) m(j) The process can then proceed to step 426.

[0087] At step 426, the optimal volume ratio correction value δ is... me The value assigned is the previous temporary volume ratio correction value δ, which is the last temporary volume ratio correction value obtained. m(j) The optimal volume ratio correction value δ corresponding to the operating condition parameter m value in step 408 is stored in memory 606. me , i.e. δ me =δ m(j) .

[0088] After step 426 is completed, the process proceeds to step 432.

[0089] At step 432, the optimal volume ratio correction value δ obtained in steps 426, 428, and 430 is used. me Calculate the optimal internal volume ratio V of compressor 102 ice The calculation formula is as follows:

[0090] V ice =δ me ×V is ,

[0091] After step 432 is completed, the process proceeds to step 434.

[0092] At step 434, based on the optimal internal volume ratio V of compressor 102 obtained in step 432... ice Adjust the position of the slide valve. After completing step 434, the process proceeds to step 436.

[0093] At step 436, it is determined whether a shutdown operation should be performed. If a shutdown is required, the process proceeds to step 438, ending the operation. If a shutdown is not required, the process proceeds to step 404, and the above steps are repeated.

[0094] Figure 5 This is a schematic diagram showing the performance trend of the compressor unit under different internal volume ratios.

[0095] like Figure 5 As shown, under a specific operating condition, the horizontal axis represents the compressor's internal volume ratio V. ic The vertical axis represents the different values ​​of COP (Coefficient of Performance) of the air conditioning system unit. It can be seen that the internal volume ratio of compressor 102 to V... ic The COP (Coefficient of Performance) of the air conditioning system exhibits a downward-opening parabolic relationship. From... Figure 4B As can be seen from step 418, after obtaining the optimal internal volume ratio V of the compressor... iceDuring the process, the internal volume of the compressor is more than V ic By gradually decreasing the value of δ, the volume ratio correction value that maximizes the unit's coefficient of performance (COP) is gradually found through parameter approximation. m This allows us to obtain the corresponding compressor internal volume ratio as the optimal internal volume ratio V. ice . Figure 5 Looking at the horizontal axis from right to left, the unit performance COP first increases and then decreases, while the internal volume ratio V... ic The value is around 2.3 (i.e., the optimal content-product ratio V). ice Approximately 2.3) The unit's COP reaches its maximum. Internal volume ratio V ic The values ​​around 2.2 to 2.4 correspond to Figure 4B Steps 424 to 426, i.e., when the coefficient of performance (COP) of the unit shows a decreasing trend, will adjust the previously obtained volume ratio correction value δ. m As the optimal volume ratio correction value δ me Calculate the optimal internal volume ratio V of the compressor. ice .

[0096] From an engineering perspective, the unit's performance COP is reflected in the heat exchange efficiency of the air conditioning system 100. When the unit's performance is optimal, the ratio of the heat exchange of the entire air conditioning system 100 (which can be reflected by the difference between the inlet and outlet water temperatures) to the current of the compressor 102 is at its maximum. This can be understood as follows: when the unit's performance is optimal, with the compressor 102's operating voltage remaining constant, a large amount of heat exchange can be achieved with relatively small energy loss (a small current).

[0097] Figure 6 for Figure 1 The block diagram of the control device 114 shown illustrates its main components. The control device 114 is capable of storing and executing data such as... Figures 4A-4B The process flow shows the procedures, stored procedures, and calls as follows: Figures 4A-4B The parameters required for the process shown.

[0098] like Figure 6As shown, the control device 114 includes a bus 602, a processor 604, a memory 606, an input interface 608, and an output interface 610. The processor 604, memory 606, input interface 608, and output interface 610 are connected to the bus 602. The processor 604 can read programs (or instructions) from the memory 606 and execute the programs (or instructions) to process data; the processor 604 can also write data or programs (or instructions) into the memory 606. The memory 606 stores programs (instructions) or data. By executing the instructions in the memory 606, the processor 604 can control the operation of the memory 606, the input interface 608, and the output interface 610. In this application, the memory 606 can store the adiabatic constants of common refrigerants mentioned in Table 1, the m-value index table in Table 2, and the volume ratio correction values ​​δ under different operating conditions. m Index table and Figures 4A-4B The procedures and parameters required for the process shown are as follows.

[0099] Input interface 608 is configured to communicate with ambient temperature sensor 130, inlet water temperature sensor 126, outlet water temperature sensor 128, system intake pressure sensor 122, system exhaust pressure sensor 124, and slide valve displacement sensor 234 via connections 632, 634, 636, 638, 640, and 642 to receive pressure and / or temperature parameters from each sensor, convert the data of these parameters into signals recognizable by processor 604, and store them in memory 606.

[0100] The processor 604 is configured to generate a slide valve position adjustment signal based on a program and various parameters stored in the memory 606.

[0101] Output interface 610 is communicatively connected to drive unit 233 of compressor 102 via connection 644. By executing the program in memory 606, control unit 114 outputs a slide valve position adjustment signal to drive unit 233 through output interface 610, thereby controlling drive unit 233 to adjust the position of slide valve 232.

[0102] The air conditioning system of this application includes, but is not limited to, the following beneficial technical effects:

[0103] First, in an air conditioning refrigeration cycle system equipped with an economizer, the gas density or pressure in the compressor's exhaust chamber is higher than in an air conditioning refrigeration cycle system without an economizer, under the same slide valve position. If the compressor's internal volume ratio is kept consistent with the air conditioning system's system volume ratio, it will lead to overcompression of the compressor, meaning the compressor's final exhaust pressure will be greater than the pressure in the refrigeration unit's exhaust pipe, resulting in low compressor operating efficiency. Therefore, it is necessary to adjust the slide valve position according to the corrected internal volume ratio of the compressor to maximize the unit's coefficient of performance and operating efficiency. This application uses parameter approximation to test the compressor's optimal operating efficiency, then reverse-engineers the volume ratio correction value for optimal compressor efficiency. The obtained volume ratio correction value under this operating condition is stored in the control device for direct retrieval under the same operating conditions in the future, thereby maximizing the overall performance of the unit.

[0104] Secondly, the air conditioning refrigeration cycle system of this application can eliminate the over-compression state of the compressor after the economizer is turned on, thereby reducing the operating noise of the unit. This over-compression state is caused by an inappropriate slide valve position of the compressor, which is obtained by making the internal volume ratio of the compressor equal to the system volume ratio of the air conditioning system.

[0105] Third, the air conditioning refrigeration cycle system of this application can eliminate the state of compressor over-compression after the economizer is turned on, thereby reducing the vibration of the unit pipeline.

[0106] Fourth, the air conditioning refrigeration cycle system of this application can eliminate the over-compression state of the compressor after the economizer is turned on, thereby extending the service life of the compressor and the unit and improving the insulation efficiency of the compressor.

[0107] Fifth, this application can independently calculate the optimal internal volume ratio of different models of compressors (including compressors with different displacements and different gas injection pressures) under various operating conditions, which can effectively avoid the impact of manufacturing differences between individual compressors and differences in actual installation environment on unit control, so that each unit can be controlled at the optimal performance point.

[0108] Although this disclosure has been described in conjunction with examples of the embodiments outlined above, various alternatives, modifications, variations, improvements, and / or substantially equivalents, whether known or now or soon to be foreseen, will likely be apparent to those skilled in the art. Therefore, the examples of embodiments of this disclosure set forth above are intended to be illustrative rather than restrictive. Various changes can be made without departing from the spirit or scope of this disclosure. Therefore, this disclosure is intended to include all known or previously developed alternatives, modifications, variations, improvements, and / or substantially equivalents. The technical effects and problems described in this specification are exemplary rather than restrictive. It should be noted that the embodiments described in this specification may have other technical effects and may solve other technical problems.

Claims

1. An air conditioning system characterized by Comprises: a compressor comprising a slide valve having a plurality of slide positions, one of the plurality of slide positions of the slide valve corresponding to one specific volume ratio of the compressor; and a control device configured to: obtain a system volume ratio and a volume ratio correction value under a current working condition; obtain an optimal volume ratio of the compressor according to the volume ratio correction value and the system volume ratio; and adjust the slide position of the slide valve according to the optimal volume ratio of the compressor; wherein the volume ratio correction value is obtained by the following steps: S01, setting a temporary volume ratio correction value and obtaining a corresponding performance coefficient of the air conditioning system; S02, gradually reducing the temporary volume ratio correction value by turns and obtaining a corresponding performance coefficient of the air conditioning system until the performance coefficient obtained at the last time is less than the performance coefficient obtained at the previous time, and assigning the volume ratio correction value as the temporary volume ratio correction value obtained at the previous time.

2. The air conditioning system of claim 1, wherein Further comprises: a plurality of sensors for determining the working condition and the system volume ratio.

3. The air conditioning system of claim 2, wherein Further comprises: an evaporator fluidly connected to the compressor; wherein the plurality of sensors comprises: a water inlet temperature sensor for detecting a water inlet temperature of the evaporator; a water outlet temperature sensor for detecting a water outlet temperature of the evaporator; and an ambient temperature sensor for detecting an ambient temperature of the air conditioning system.

4. The air conditioning system according to claim 3, wherein: the compressor further comprises a screw, and the control device is configured to obtain a rotational speed of the screw; and the control device determines the working condition by measuring the ambient temperature, the water inlet temperature, the water outlet temperature and the rotational speed of the screw.

5. The air conditioning system of claim 3, wherein The plurality of sensors further comprises: a system suction pressure sensor for detecting a suction pressure of the air conditioning system; and a system discharge pressure sensor for detecting a discharge pressure of the air conditioning system, wherein the control device determines the system volume ratio by measuring the suction pressure and the discharge pressure.

6. The air conditioning system according to claim 5, wherein: the control device is further configured to obtain a current parameter of the compressor, and the performance coefficient of the air conditioning system is obtained according to the current parameter, the water inlet temperature and the water outlet temperature, wherein the performance coefficient of the air conditioning system is maximum when the compressor is at the optimal volume ratio.

7. The air conditioning system of claim 6, wherein Further comprises: an economizer fluidly connected to the compressor; wherein the optimal volume ratio is equal to the system volume ratio when the economizer is in a closed state.

8. The air conditioning system of claim 7, wherein The compressor comprises: a suction port, a charge port, a discharge port and a slide valve displacement sensor, wherein the control device adjusts the slide position of the slide valve through the slide valve displacement sensor, and wherein the economizer is connected to the compressor through the charge port.

9. The air conditioning system of claim 8, wherein Further comprises: a suction pipe connected to the suction port of the compressor, wherein the system suction pressure sensor is disposed in the suction pipe, and the evaporator is connected to the compressor through the suction pipe; an exhaust pipe connected to the exhaust port of the compressor, wherein the system exhaust pressure sensor is disposed in the exhaust pipe; a condenser connected to the compressor through the exhaust pipe, and the condenser is in fluid communication with the economizer; an economizer expansion valve in fluid communication with the condenser and the economizer; and a main expansion valve in fluid communication with the evaporator and the economizer. 10.A control method for controlling a compressor in an air conditioning system, the compressor comprising a slide valve, the control method comprising the steps of: determining a working condition and a system volume ratio of the air conditioning system; obtaining a volume ratio correction value under the working condition; obtaining an optimal content volume ratio of the compressor according to the volume ratio correction value and the system volume ratio; and adjusting a sliding position of the slide valve according to the optimal content volume ratio of the compressor; the volume ratio correction value is obtained by the steps of: wherein S01, setting a temporary volume ratio correction value and obtaining a corresponding coefficient of performance (COP) of the air conditioning system; S02, gradually reducing the temporary volume ratio correction value step by step and obtaining a corresponding COP of the air conditioning system, until the COP obtained at the last time is less than the COP obtained at the previous time, and assigning the volume ratio correction value as the temporary volume ratio correction value obtained at the previous time. 11.The control method of claim 10, wherein: the air conditioning system comprises: a plurality of sensors through which the working condition and the system volume ratio of the air conditioning system are determined; an evaporator in fluid communication with the compressor; and a control device; wherein the plurality of sensors comprises: a water inlet temperature sensor for detecting a water inlet temperature of the evaporator; a water outlet temperature sensor for detecting a water outlet temperature of the evaporator; and an ambient temperature sensor for detecting an ambient temperature of the air conditioning system. 12.The control method of claim 11, wherein: the compressor further comprises a screw, and the control device is configured to obtain a rotational speed of the screw; and the control device determines the working condition by measuring the ambient temperature, the water inlet temperature, the water outlet temperature, and the rotational speed of the screw. 13.The control method of claim 11, wherein: the plurality of sensors further comprises: a system suction pressure sensor for detecting a suction pressure of the air conditioning system; and a system exhaust pressure sensor for detecting an exhaust pressure of the air conditioning system, wherein the control device determines the system volume ratio by measuring the suction pressure and the exhaust pressure. ​ 14. The control method of claim 13, wherein: the control device is further configured to obtain a current parameter of the compressor, and a coefficient of performance of the air conditioning system is obtained according to the current parameter, the inlet water temperature and the outlet water temperature, wherein the coefficient of performance of the air conditioning system is maximum when the compressor is at the optimal volume ratio.

15. The control method of claim 14, wherein: the air conditioning system further comprises: an economizer fluidly connected to the compressor, wherein the optimal volume ratio is equal to the system volume ratio when the economizer is in a closed state.

16. The control method of claim 15, wherein: the compressor further comprises: a suction port, a suction port, a discharge port and a slide valve displacement sensor, wherein the control device adjusts a slide position of the slide valve through the slide valve displacement sensor, and wherein the economizer is connected to the compressor through the suction port.

17. The control method of claim 16, wherein: the air conditioning system further comprises: a suction pipe connected to the suction port of the compressor, wherein the system suction pressure sensor is disposed in the suction pipe through which the evaporator is connected to the compressor; a discharge pipe connected to the discharge port of the compressor, wherein the system discharge pressure sensor is disposed in the discharge pipe; a condenser connected to the compressor through the discharge pipe, and the condenser is in fluid communication with the economizer; an economizer expansion valve in fluid communication with the condenser and the economizer; and a main expansion valve in fluid communication with the evaporator and the economizer.

18. A compressor, wherein: the compressor is adjusted by the control method of any one of the preceding claims 10-17.

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