Two-stage compression centrifugal device, its intermediate gas replenishment control method, and heating device

Abstract

The two-stage compression centrifugal device comprises a two-stage centrifugal compressor, an evaporator, a condenser, an economizer, a gas make-up valve, and a calculation module, wherein the first-stage intake port of the two-stage centrifugal compressor is connected to the exhaust port of the evaporator, the second-stage exhaust port of the two-stage centrifugal compressor is connected to the intake port of the condenser, the economizer is connected between the intake port of the evaporator and the exhaust port of the condenser, and the economizer is connected to the first-stage exhaust port and the second-stage intake port of the two-stage centrifugal compressor respectively through the gas make-up valve, and the calculation module calculates an actual gas make-up amount and an optimal gas make-up amount based on operating parameters of the two-stage compression centrifugal device to adjust the opening degree of the gas make-up valve.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application filed with the State Intellectual Property Administration of the People's Republic of China on March 13, 2023, bearing application number 202310239288.7, for an invention entitled "Two-stage compression centrifugal device and method for controlling intermediate gas replenishment in a two-stage compression centrifugal device," the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to the technical field of refrigeration, and more particularly to a two-stage compression centrifugal device and its intermediate gas replenishment control method, and a heating device. [Background technology]

[0003] The two-stage compression centrifugal device uses an economizer between the stages to increase the enthalpy of the intermediate gas supply to improve energy efficiency, but the control method for the intermediate gas supply has the following problems:

[0004] The amount of gas replenishment is not controlled, resulting in poor energy efficiency and the risk of liquid in the replenishment gas (the replenishment gas contains liquid). No valves are added to the replenishment gas line, so the amount of gas replenishment is not adjusted. The dimensions of the economizer gas replenishment duct are determined based on the amount of gas replenishment at full load under the single-name designed operating condition. When the unit operates under certain loads or modulation modes, such as ice storage and air conditioning dual mode or air conditioning and heat recovery dual mode, the amount of gas replenishment may be too large or too small, preventing the enthalpy increase effect of gas replenishment from being fully realized and seriously affecting the reliable operation of the unit.

[0005] To solve the above problems, the gas supply valve is increased to control the gas supply amount, but this simply prevents the risk of gas supply leakage and performs rough control, and the gas supply amount is not accurately adjusted, so the gas supply amount is not in the optimal gas supply amount range. At the same time, the gas supply control cannot dynamically adjust to changes in load and operating mode, such as pressure ratio, outlet water temperature, and subcooling degree, so the gas supply increase enthalpy effect cannot be optimally exerted, and efficient and stable operation of the unit in all modes cannot be achieved. Summary of the Invention

[0006] The present disclosure aims to at least partially solve the technical problem that the gas replenishment amount of the conventional two-stage compression centrifugal device is not within the optimum gas replenishment amount range.

[0007] To achieve the above object, a first aspect of the present disclosure provides a two-stage compression centrifugal compressor, comprising: a two-stage centrifugal compressor; an evaporator; a condenser; an economizer; a gas make-up valve; and a calculation module, wherein a first-stage intake port of the two-stage centrifugal compressor is connected to an exhaust port of the evaporator; a second-stage exhaust port of the two-stage centrifugal compressor is connected to an intake port of the condenser; the economizer is connected between the intake port of the evaporator and the exhaust port of the condenser; and the economizer is connected to the first-stage exhaust port and the second-stage intake port of the two-stage centrifugal compressor, respectively, through the gas make-up valve; and the calculation module calculates an actual gas make-up amount and an optimal gas make-up amount based on operating parameters of the two-stage compression centrifugal device to adjust the opening degree of the gas make-up valve.

[0008] The two-stage compression centrifugal device provided by the present disclosure includes a calculation module, which obtains operating parameters of the two-stage compression centrifugal device, calculates an optimal gas supply amount and an actual gas supply amount based on the operating parameters of the two-stage compression centrifugal device, and adjusts the opening degree of the gas supply valve, so that the adjusted actual gas supply amount of the gas supply valve is within the optimal gas supply amount range.

[0009] In addition, the two-stage compression centrifugal device of the present disclosure further has the following additional technical features.

[0010] In some embodiments of the present disclosure, the calculation module calculates the actual gas replenishment amount δ m based on the following formula:

[0011]

number

[0012] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´] : Enthalpy value of two-stage intake, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0013] In some embodiments of the present disclosure, the calculation module calculates the optimum gas replenishment amount Tδm based on the following formula:

[0014]

number

[0015] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´´] : Optimal two-stage intake enthalpy value, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0016] In some embodiments of the present disclosure, the operating parameters include a temperature parameter and a pressure parameter, and the calculation module is configured to calculate h based on the temperature parameter and the pressure parameter by referring to a temperature, pressure and enthalpy value comparison table and / or a pressure and saturation enthalpy value comparison table. 0[1] , h 0[3] , h 0[3´] , h 0[3´´] , h 0[4] , h 0[5] , h 0[7] Get.

[0017] In some embodiments of the present disclosure, the device further includes a control module, which adjusts the opening degree of the gas replenishment valve using the optimal gas replenishment amount as a control target and the actual gas replenishment amount as a feedback amount.

[0018] A second aspect of the present disclosure is an intermediate gas replenishment control method for a two-stage compression centrifugal device, which is performed by the two-stage compression centrifugal device according to the first aspect of the present disclosure, comprising: receiving operating parameters of the two-stage compression centrifugal device; The method includes calculating an optimum gas supply amount and an actual gas supply amount based on the operating parameters of the two-stage compression centrifugal device to adjust the opening degree of the gas supply valve.

[0019] The intermediate gas supply control method for a two-stage compression centrifugal device provided by the present disclosure calculates an optimal gas supply amount and an actual gas supply amount based on the operating parameters of the two-stage compression centrifugal device, and adjusts the opening degree of the gas supply valve based on the optimal gas supply amount and the actual gas supply amount, so that the actual gas supply amount of the gas supply valve is within the optimal gas supply amount range.

[0020] In some embodiments of the present disclosure, the actual gas replenishment amount δm is calculated by the following formula:

[0021]

number

[0022] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´] : Enthalpy value of two-stage intake, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0023] In some embodiments of the present disclosure, the optimum gas replenishment amount Tδm is calculated by the following formula:

[0024]

number

[0025] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´´] : Optimal two-stage intake enthalpy value, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0026] In some embodiments of the present disclosure, the method further includes setting the optimum gas replenishment amount as a control target, setting the actual gas replenishment amount as a feedback amount, and adjusting the opening degree of the gas replenishment valve to a first opening degree.

[0027] In some embodiments of the present disclosure, Obtaining two-stage intake superheat at the two-stage intake; determining whether the two-stage intake superheat is within a preset range; maintaining the gas supply valve at the first opening degree based on the two-stage intake superheat being within the preset range; Controlling the first opening degree to reduce the opening degree based on the fact that the two-stage intake superheat is less than a preset intake superheat lower limit value; The method further includes energy adjusting and controlling the first opening degree based on the two-stage intake superheat being greater than a preset intake superheat upper limit value.

[0028] In some embodiments of the present disclosure, Obtaining two-stage exhaust superheat at the two-stage exhaust outlet; determining whether the second-stage exhaust superheat is within a preset range; maintaining the gas make-up valve at the first opening degree based on the second-stage exhaust superheat being within the preset range; Controlling the first opening degree to reduce the opening degree based on the fact that the second-stage exhaust superheat is less than a preset exhaust superheat lower limit value; The method further includes energy adjusting and controlling the first opening degree based on the second-stage exhaust superheat being greater than a preset exhaust superheat upper limit value.

[0029] A third aspect of the present disclosure provides a heating device including the two-stage compression centrifugal device according to any one of the technical solutions of the first aspect. [Brief explanation of the drawings]

[0030] Various other benefits and advantages will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments. The drawings are used only to illustrate the preferred embodiments and are not to be construed as limiting the disclosure. Also, like parts are designated by like reference numerals throughout the drawings.

[0031] [Figure 1] 1 shows a structural schematic diagram of a two-stage compression centrifugal device according to some embodiments of the present disclosure. [Figure 2] 1 shows a diagram of pressure and enthalpy values ​​for a two-stage compression centrifugal device according to some embodiments of the present disclosure. [Figure 3] 1 shows a flowchart of a method for controlling intermediate gas make-up in a two-stage compression centrifugal device according to some embodiments of the present disclosure. [Figure 4] 1 shows a flowchart of a method for controlling intermediate gas make-up in a two-stage compression centrifugal device according to some embodiments of the present disclosure. [Figure 5] 1 shows a flowchart of a method for controlling intermediate gas make-up in a two-stage compression centrifugal device according to some embodiments of the present disclosure. [Figure 6] 1 shows a flowchart of a method for controlling intermediate gas make-up in a two-stage compression centrifugal device according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the drawings. Although the drawings show exemplary embodiments of the present disclosure, it should be understood that the present disclosure should not be limited to the embodiments described herein, but may be realized in various forms. On the contrary, these embodiments are provided to facilitate a better understanding of the present disclosure and to fully convey the scope of protection of the present disclosure to those skilled in the art.

[0033] It is to be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "said" can also refer to the plural, unless the context clearly dictates otherwise. The terms "comprise," "comprise," "contain," and "have" are inclusive. Thus, while indicating the presence of stated features, steps, operations, elements, and / or components, they do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. Method steps, processes, and operations described herein should not be construed as requiring execution in the particular order described or illustrated, unless an order of execution is explicitly indicated. It should also be understood that additional or alternative steps may be employed.

[0034] Although multiple elements, components, regions, layers, and / or sections may be described herein using terms such as first, second, and third, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to separate one element, component, region, layer, or segment from another region, layer, or segment. Unless explicitly indicated by context, terms such as "first," "second," and other digital terms do not imply an order or sequence when used herein. Thus, a first element, component, region, layer, or segment described below could be referred to as a second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0035] For ease of explanation, spatially relative terms may be used herein to describe the relationship of one element or feature, as illustrated, to another element or feature, such as "inside," "outside," "inside," "outside," "below," "downward," "above," "above," etc. Such spatially relative terms are meant to include different orientations of the device in use or operation other than the orientation shown. For example, if a device in the figures is inverted, elements described as "under other elements or features" or "underneath other elements or features" would be oriented "above other elements or features" or "above other elements or features." Thus, examples of the term "under..." can include both above and below orientations. Devices can also have orientations (rotated 90 degrees or other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0036] 1 shows a structural schematic diagram of a two-stage compression centrifugal device according to an embodiment of the present disclosure. Referring to FIG. 1, some embodiments of a first aspect of the present disclosure provide a two-stage compression centrifugal device 100 including a two-stage centrifugal compressor 2, an evaporator 8, a condenser 5, an economizer 7, a gas make-up valve 6, and a calculation module (not shown).

[0037] The first-stage intake port of the two-stage centrifugal compressor 2 is connected to the exhaust port of the evaporator 8, the second-stage exhaust port of the two-stage centrifugal compressor 2 is connected to the intake port of the condenser 5, and an economizer 7 is provided between the intake port of the evaporator 8 and the exhaust port of the condenser 5, and the economizer 7 is further connected to the first-stage exhaust port and the second-stage intake port of the two-stage centrifugal compressor 2, respectively, by a gas make-up valve 6. The calculation module receives the operating parameters of the two-stage compression centrifugal device 100 and calculates the optimal gas make-up amount and the actual gas make-up amount based on the operating parameters of the two-stage compression centrifugal device 100 to adjust the opening degree of the gas make-up valve 6.

[0038] The two-stage compression centrifugal device 100 provided by the present disclosure includes a calculation module, which receives operating parameters of the two-stage compression centrifugal device 100, calculates an optimal gas supply amount and an actual gas supply amount based on the operating parameters of the two-stage compression centrifugal device 100, and adjusts the opening degree of the gas supply valve 6 so that the adjusted actual gas supply amount of the gas supply valve 6 is within the optimal gas supply amount range.

[0039] The two-stage centrifugal compressor 2 includes a first-stage compressor and a second-stage compressor, the first-stage compressor including a first-stage intake port and a first-stage exhaust port, and the two-stage compressor including a second-stage intake port and a second-stage exhaust port. The arrows in Fig. 1 indicate the direction of refrigerant flow. The first-stage intake port of the two-stage centrifugal compressor 2 is connected to the evaporator 8 by an intake pipe 1, and a first pressure sensor 11 and a first temperature sensor 12 are provided on this intake pipe 1 to measure the first-stage intake pressure P1 (the pressure of the refrigerant at the first-stage intake port) and the first-stage intake temperature T1 (the temperature of the refrigerant at the first-stage intake port). The first-stage exhaust port is connected to the second-stage intake port by a connecting pipe 3, and the refrigerant output from the first-stage exhaust port is sent to the second-stage intake port by the connecting pipe 3. A second pressure sensor 31 and a second temperature sensor 32 are provided on this connecting pipe 3. The second pressure sensor 31 measures the second-stage intake pressure P3' (the pressure of the refrigerant at the second-stage intake port), and the second temperature sensor 32 measures the second-stage intake temperature T3' (the temperature of the refrigerant at the second-stage intake port). The second-stage exhaust port of the two-stage centrifugal compressor 2 is connected to the condenser 5 by an exhaust pipe 4. A third pressure sensor 41 and a third temperature sensor 42 are provided on this exhaust pipe 4 to measure the second-stage exhaust pressure P4 (the pressure of the refrigerant at the second-stage exhaust port) and the second-stage exhaust temperature T4 (the temperature of the refrigerant at the second-stage exhaust port). The two-stage centrifugal compressor 2 receives low-temperature, low-pressure refrigerant from the evaporator 8 through an intake pipe 1, compresses it in two stages to obtain high-temperature, high-pressure refrigerant, and sends this high-temperature, high-pressure refrigerant to a condenser 5 through an exhaust pipe 4.

[0040] The economizer 7 is connected to the connecting line 3 via a gas make-up line, and the gas make-up valve 6 is provided on the gas make-up line. The function of the economizer 7 is to provide intermediate gas make-up to the two-stage centrifugal compressor 2. That is, the economizer 7 sends additional refrigerant to the connecting line 3 via the gas make-up line, and the additional refrigerant is sent to the second-stage inlet of the second-stage compressor together with the refrigerant output from the first-stage outlet of the connecting line 3. The gas make-up valve 6 adjusts the make-up gas flow rate of the economizer 7. A fourth pressure sensor 61 and a fourth temperature sensor 62 are both provided on the gas make-up line. Specifically, the fourth pressure sensor 61 and the fourth temperature sensor 62 are both provided on a segment of the gas make-up line between the gas make-up valve 6 and the connecting line 3. Thus, the fourth pressure sensor 61 and the fourth temperature sensor 62 measure the pressure and temperature of the refrigerant output from the gas make-up valve 6. The fourth pressure sensor 61 measures the pressure of the refrigerant output from the gas make-up valve 6 and is defined as a gas make-up pressure P6, the fourth temperature sensor measures the temperature of the refrigerant output from the gas make-up valve 6 and is defined as a gas make-up temperature T6. The fifth pressure sensor 9 measures the pressure of the refrigerant in the condenser 5 and this pressure is defined as a condenser pressure P5, and the sixth pressure sensor 13 measures the pressure of the refrigerant in the evaporator 8 and this pressure is defined as an evaporator pressure P8.

[0041] Referring to FIG. 2, 4 to 5 indicate the refrigerant flowing through the condenser 5. The high-temperature, high-pressure refrigerant gas exchanges heat with the coolant in the condenser 5, transferring heat to the coolant and condensing the refrigerant gas into a high-pressure liquid. During this process, the refrigerant pressure remains constant but the enthalpy value decreases, i.e., the temperature decreases. 5 to 6 indicate the refrigerant flowing through the first-stage throttle valve 10. During this process, the refrigerant flow rate is restricted, so the temperature remains constant but the pressure decreases. 7 to 8 indicate the refrigerant flowing through the second-stage throttle valve 14. During this process, the refrigerant flow rate is restricted, so the temperature remains constant but the pressure decreases. 8 to 1 indicate the refrigerant flowing through the evaporator 8. During this process, the refrigerant pressure remains constant but the enthalpy value increases, i.e., the temperature increases, indicating the refrigerant evaporates. 1 to 3 indicate the operating process of the first-stage compressor. During this process, the refrigerant pressure increases and the temperature increases. 3 to 3' indicate the gas replenishment process. During this process, the pressure remains constant but the enthalpy value increases. 3' to 4 show the operation process of the two-stage compressor, during which the refrigerant pressure increases and the temperature rises.

[0042] The first pressure sensor 11, the first temperature sensor 12, the second pressure sensor 31, the second temperature sensor 32, the third pressure sensor 41, the third temperature sensor 42, the fourth pressure sensor 61, the fourth temperature sensor 62, the fifth pressure sensor 9, and the sixth pressure sensor 13 are all communicatively connected (specifically, electrically connected) to the calculation module, and the calculation module can receive the pressure parameters measured by the pressure sensors and the temperature parameters measured by the temperature sensors in real time. The first pressure sensor 11, the first temperature sensor 12, the second pressure sensor 31, the second temperature sensor 32, the third pressure sensor 41, the third temperature sensor 42, the fourth pressure sensor 61, the fourth temperature sensor 62, the fifth pressure sensor 9, and the sixth pressure sensor 13 constitute the collection module.

[0043] The collection module is designed to measure the input power W of the two-stage centrifugal compressor. comp and the total heat exchange amount of the compressor Q loss The input power W of the two-stage centrifugal compressor can be collected in real time and transmitted to the calculation module. comp and the total heat exchange amount of the compressor Q lossThe input power W of the two-stage centrifugal compressor can be received in real time. comp can be obtained by multiplying the current and voltage input to the two-stage centrifugal compressor 2, whereby the calculation module calculates W comp The total heat exchange rate of the compressor is Q loss =Q air.con +Q air.rad +Q ref Q air.con is the amount of convective heat exchange between the two-stage centrifugal compressor and the air, and Q air.rad is the amount of radiant heat exchange in the two-stage centrifugal compressor, and Q ref is the heat carried away by the refrigerant.

[0044] The calculation module stores a temperature, pressure, and enthalpy value comparison table for various refrigerants, as well as a saturation pressure and enthalpy value comparison table. For a specific refrigerant, after its temperature and pressure are determined, its enthalpy value can be uniquely determined in the temperature, pressure, and enthalpy value comparison table. The refrigerants may be R134A, R123, R245fa, R1233zd(E), R1336mzz(Z), R1224yd(Z), R514A, R1234ze(E), R513A, or R5158B. In this embodiment, the refrigerant is R134A. The first-stage intake pressure P1 and first-stage intake temperature T1 are obtained from the temperature, pressure, and enthalpy value comparison table for R134A, and then the enthalpy value h of the first-stage intake is calculated. 0[1] After obtaining the second stage intake pressure P3' and the second stage intake temperature T3', the enthalpy value h of the second stage intake of the compressor 0[3´] The second-stage exhaust pressure P4, the second-stage exhaust temperature T4 can be determined, and the enthalpy value h of the second-stage exhaust port can be obtained. 0[4] The gas supply pressure P6 and gas supply temperature T6 can be determined, and the enthalpy value h of the gas supply valve can be obtained. 0[3] The enthalpy value of the condenser, h 0[5]represents the enthalpy value of the refrigerant in the condenser 5. The condenser pressure P5 is acquired, and in some embodiments (when there is no subcooling in the condenser), the condenser pressure P5 is the saturation pressure of the refrigerant in the condenser. This saturation pressure is measured by the fifth pressure sensor 9, and the condenser enthalpy value h is calculated based on a saturation pressure vs. enthalpy value table. 0[5] Alternatively, in some embodiments (when the condenser has no subcooling), the condenser pressure P5 is the pressure of the refrigerant at the condenser outlet, and the temperature of the refrigerant at the condenser outlet is further measured, and the condenser enthalpy value h is determined based on a temperature, pressure and enthalpy value comparison table. 0[5] h 0[7] represents the enthalpy value at the economizer outlet. From the pressure and enthalpy value diagram in Figure 2, it can be seen that the enthalpy value does not change from the economizer 7 to the evaporator 8. Therefore, although a two-stage throttle valve 14 is installed between the economizer 7 and the evaporator 8, the pressure drop enthalpy value of the two-stage throttle valve 14 does not change, and the economizer outlet enthalpy value h 0[7] is numerically equal to the evaporator enthalpy value, which represents the refrigerant enthalpy value in the evaporator, so the evaporator pressure P8 can be measured by the sixth pressure sensor 13 to obtain the evaporator pressure P8. In some embodiments, the evaporator pressure P8 is the saturation pressure of the refrigerant in the evaporator, and the evaporator enthalpy value can be determined based on a saturation pressure vs. enthalpy value comparison table, and the evaporator enthalpy value can be used as the economizer outlet enthalpy value h 0[7] It is calculated as follows.

[0045] The calculation module stores an energy conservation equation established using the two-stage centrifugal compressor 2 as a control body.

[0046]

number

[0047] The calculation module stores the energy conservation equation established with the economizer 7 as the control body.

[0048]

number

[0049] From the above two equations, the actual gas replenishment amount Δm is calculated as follows:

[0050]

number

[0051] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´] : Enthalpy value of two-stage intake, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0052] To calculate the optimal gas replenishment amount Tδm, the energy conservation equation is established again.

[0053]

number

[0054] Unlike the energy conservation equation established to calculate the actual gas replenishment amount, h 0[3´] h 0[3´´] is replaced by, where h 0[3´´] is the enthalpy value of the optimal two-stage inlet. The enthalpy value of the optimal two-stage inlet h 0[3´´]is determined by combining the target second stage intake pressure Pmth, the second stage intake temperature T3', and the temperature, pressure and enthalpy value comparison table stored in the calculation module, where the target second stage intake pressure Pmth=(P5*P8)^0.5, where P5 is the condenser pressure and P8 is the evaporator pressure.

[0055] The optimum gas replenishment amount Tδm is calculated again using the two energy conservation equations.

[0056]

number

[0057] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´´] : Optimal two-stage intake enthalpy value, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0058] After the calculation module calculates the optimal gas supply amount Tδm and the actual gas supply amount δm, it sends the optimal gas supply amount Tδm and the actual gas supply amount δm to the control module and issues a gas supply valve adjustment command. The control module is communicatively connected to the calculation module, specifically, electrically connected to the calculation module. The control module receives the optimal gas supply amount Tδm and the actual gas supply amount δm, and adjusts the opening of the gas supply valve 6 using the optimal gas supply amount Tδm as a control target and the actual gas supply amount δm as a feedback value. If the optimal gas supply amount Tδm is greater than the actual gas supply amount δm, the opening of the gas supply valve 6 is increased. If the optimal gas supply amount Tδm is equal to the actual gas supply amount δm, the opening of the gas supply valve 6 is maintained. If the optimal gas supply amount Tδm is less than the actual gas supply amount δm, the opening of the gas supply valve 6 is decreased.

[0059] The control module can further determine the range for adjusting the opening degree of the gas supply valve 6 based on the difference between the optimum gas supply amount Tδm and the actual gas supply amount δm. After the adjustment, the opening degree of the gas supply valve 6 is the first opening degree. Because the calculation module makes the actual gas supply amount δm of the gas supply valve 6 approach the optimum gas supply amount Tδm in real time, the actual gas supply amount δm can fall into the optimum gas supply amount range, thereby achieving a better gas supply effect.

[0060] After adjusting the opening degree of the gas make-up valve 6 to the first opening degree, the control module further obtains the second-stage intake superheat Tsh3' at the second-stage intake port. Alternatively, the control module obtains the second-stage exhaust superheat Tsh4 at the second-stage exhaust port and determines whether the second-stage intake superheat Tsh3' is within a preset range. Alternatively, the control module determines whether the second-stage exhaust superheat Tsh4 is within a preset range, and if the second-stage intake superheat Tsh3' is within the preset range or the second-stage exhaust superheat Tsh4 is also within the preset range, the gas make-up valve 6 maintains the first opening degree.

[0061] The method for calculating the second-stage intake superheat Tsh3' is to obtain the second-stage intake pressure P3' and the second-stage intake temperature T3', and then obtain the saturation temperature TP3' corresponding to the second-stage intake pressure P3' using the second-stage intake pressure P3', and then the second-stage intake superheat Tsh3' = T3' - TP3'. The method for calculating the second-stage exhaust superheat Tsh4 is to obtain the second-stage exhaust pressure P4 and the second-stage exhaust temperature T4, and then obtain the saturation temperature Tp4 corresponding to the second-stage exhaust pressure P4 using the second-stage exhaust pressure P4, and then the second-stage exhaust superheat Tsh4 = T4 - Tp4.

[0062] Furthermore, if the two-stage intake superheat Tsh3' is less than the predetermined intake superheat lower limit value, or if the two-stage exhaust superheat Tsh4 is less than the predetermined exhaust superheat lower limit value, the control module controls the gas make-up valve 6 to reduce its opening, and if the two-stage intake superheat is greater than the predetermined intake superheat Tsh3' upper limit value, or if the two-stage exhaust superheat Tsh4 is greater than the predetermined exhaust superheat upper limit value, the control module energy adjusts and controls the gas make-up valve 6 (energy adjustment and control means controlling the amount of refrigerant circulating by adjusting the opening of the gas make-up valve 6).

[0063] In some embodiments of the present disclosure, when the control module energy adjusts and controls the gas replenishment valve 6, the control module obtains the second-stage intake pressure P3' and determines whether the second-stage intake pressure P3' has reached the current target second-stage intake pressure value Pmth; if the second-stage intake pressure P3' has not reached the current target intake pressure value Pmth, the control module controls the opening degree of the gas replenishment valve 6 to be larger or smaller, so that the second-stage intake pressure P3' reaches the current target intake pressure value Pmth.

[0064] After adjusting the opening of the gas supply valve 6 to the first opening, the actual gas supply amount δm is adjusted a second time as described above, thereby avoiding the risk of gas supply zone liquid leakage and realizing safe and reliable operation of the two-stage compression centrifugal device 100.

[0065] The beneficial effects of the two-stage compression centrifugal device 100 provided by the present disclosure are as follows: First, the first stage intake pressure P1, the first stage intake temperature T1, the second stage intake pressure P3', the second stage intake temperature T3', the gas make-up pressure P6, the gas make-up temperature T6, the second stage exhaust pressure P4, the second stage exhaust temperature T4, the condenser pressure P5, and the evaporator pressure P8 are measured in real time by a plurality of temperature sensors and a plurality of pressure sensors. The calculation module receives these temperature parameters and pressure parameters and calculates the input power W of the two-stage centrifugal compressor. comp and the total heat exchange amount of the compressor Q loss The calculation module of the two-stage compression centrifugal device 100 substitutes the above operating parameters into the energy conservation equation established as the control body of the two-stage centrifugal compressor 2 stored therein and the energy conservation equation established as the control body of the economizer 7 to calculate the optimal gas replenishment amount Tδm and the actual gas replenishment amount δm, and adjusts the aperture of the gas replenishment valve 6. If the actual gas replenishment amount δm is different from the optimal gas replenishment amount Tδm, the module issues a gas replenishment valve adjustment command, and the control module receives the optimal gas replenishment amount Tδm and the actual gas replenishment amount δm. The optimal gas replenishment amount Tδm is used as the control target and the actual gas replenishment amount δm is used as the feedback value to adjust the aperture of the gas replenishment valve 6, thereby adjusting the actual gas replenishment amount δm to approach the optimal gas replenishment amount Tδm in real time, and the adjusted actual gas replenishment amount δm is within the optimal gas replenishment amount range. Next, by installing pressure sensors and temperature sensors and adding a calculation module, the actual gas supply amount δm and the optimal gas supply amount Tδm can be calculated, which realizes low-cost and accurate detection of the two-stage compression centrifugal device 100. With high detection accuracy, the actual gas supply amount δm of the two-stage compression centrifugal device 100 can be accurately controlled. When the actual gas supply amount δm of the gas supply valve 6 is within the optimal gas supply amount range, the structural complexity of the two-stage compression centrifugal device 100 is not increased, and the online self-adaptation of the gas supply amount can be dynamically adjusted according to changes in load and operating mode, and the advantages of the gas supply increase enthalpy of the two-stage centrifugal compressor 2 can be fully utilized.

[0066] 3 shows a flowchart of an intermediate gas supply control method for the two-stage compression centrifugal device 100 according to an embodiment of the present disclosure. Referring to FIG. 3, some examples of the second aspect of the present disclosure include a method of intermediate gas supply control for the two-stage compression centrifugal device, which is implemented by the two-stage compression centrifugal device 100 according to the first aspect of the present disclosure, comprising: receiving operating parameters for the two-stage compression centrifuge device; The method includes calculating the actual gas replenishment amount δm and the optimum gas replenishment amount Tδm based on the operating parameters of the two-stage compression centrifugal device 100 so as to adjust the opening degree of the gas replenishment valve 6.

[0067] The operating parameters of the two-stage compression centrifugal device 100 include the first stage intake pressure P1, the first stage intake temperature T1, the second stage intake pressure P3', the second stage intake temperature T3', the second stage exhaust pressure P4, the second stage exhaust temperature T4, the gas make-up pressure P6, the gas make-up temperature T6, the condenser pressure P5, and the evaporator pressure P8. Based on the above temperature parameters, pressure parameters, and temperatures, the pressure vs. enthalpy value comparison table and / or the pressure vs. saturation enthalpy value comparison table, h 0[1] , h 0[3] , h 0[3´] , h 0[4] , h 0[5] , h 0[7] Determine the input power W of the two-stage centrifugal compressor comp and the total heat exchange amount of the compressor Q loss The actual gas replenishment amount δm is calculated using the following formula:

[0068]

number

[0069] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´]: Enthalpy value of two-stage intake, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0070] The method for calculating the optimum gas replenishment amount based on the operating parameters of the two-stage compression centrifugal device 100 includes: Based on the first stage intake pressure P1, first stage intake temperature T1, target second stage intake pressure Pmth, second stage intake temperature T3', second stage exhaust pressure P4, second stage exhaust temperature T4, gas make-up pressure P6, gas make-up temperature T6, condenser pressure P5, evaporator pressure P8 and temperature, pressure and enthalpy value comparison table and / or pressure and saturated enthalpy value comparison table, h 0[1] , h 0[3] , h 0[3´´] , h 0[4] , h 0[5] , h 0[7] Determine the input power W of the two-stage centrifugal compressor comp , the total heat exchange amount of the compressor Q loss The optimum gas replenishment amount Tδm is calculated using the following equation:

[0071]

number

[0072] m1: refrigerant mass in the first stage of circulation compression of a two-stage centrifugal compressor, W comp : input power of two-stage centrifugal compressor, Q loss : total heat exchange amount of two-stage centrifugal compressor, h 0[1] : Enthalpy value of the first stage intake, h 0[3] : Enthalpy value of gas supply valve, h 0[3´´] : Optimal two-stage intake enthalpy value, h 0[4] : Enthalpy value of the two-stage exhaust port, h 0[5] : condenser enthalpy value, h 0[7] : Economizer outlet enthalpy value.

[0073] 4 shows a flowchart of a method for controlling intermediate gas supply in a two-stage compression centrifugal device according to an embodiment of the present disclosure. Referring to FIG. 4, after "calculating the actual gas supply amount δm and the optimum gas supply amount Tδm based on the operating parameters of the two-stage compression centrifugal device 100 and adjusting the aperture of the gas supply valve 6," the method further includes "setting the optimum gas supply amount as a control target and the actual gas supply amount as a feedback value, and adjusting the gas supply valve to a first aperture."

[0074] 5 shows a flowchart of the intermediate gas supply control method for a two-stage compression centrifugal device according to an embodiment of the present disclosure. Referring to FIG. 5, after "setting the optimum gas supply amount as a control target and the actual gas supply amount as a feedback value, adjusting the opening of the gas supply valve 6, and adjusting the gas supply valve 6 to a first opening," Obtaining a two-stage intake superheat Tsh3´ with a two-stage intake, Determining whether the two-stage intake superheat Tsh3' is within a preset range; Maintaining the gas supply valve 6 at the first opening degree based on the two-stage intake superheat Tsh3' being within a preset range; Controlling the first opening to be smaller based on the fact that the two-stage intake superheat Tsh3' is less than a preset intake superheat lower limit value; The method further includes energy adjusting and controlling the first opening degree based on the two-stage intake superheat Tsh3' being greater than a preset intake superheat upper limit value.

[0075] Referring to FIG. 6, as an option, "the optimum gas supply amount is set as a control target, the actual gas supply amount is set as a feedback value, the opening degree of the gas supply valve 6 is adjusted, and the gas supply valve 6 is adjusted to the first opening degree"; Obtaining two-stage exhaust superheat Tsh4 with two-stage exhaust port, Determining whether the two-stage exhaust superheat Tsh4 is within a preset range; Maintaining the gas supply valve 6 at the first opening degree based on the second-stage exhaust superheat Tsh4 being within a preset range; Controlling the first opening to be smaller based on the fact that the second-stage exhaust superheat Tsh4 is less than a preset exhaust superheat lower limit value; The method further includes energy adjusting and controlling the first opening degree based on the second-stage exhaust superheat Tsh4 being greater than a preset exhaust superheat upper limit value.

[0076] The method for calculating the second-stage intake superheat Tsh3' is to obtain the second-stage intake pressure P3' and the second-stage intake temperature T3', and then obtain the saturation temperature TP3' corresponding to the second-stage intake pressure P3' using the second-stage intake pressure P3', and then the second-stage intake superheat Tsh3' = T3' - TP3'. The method for calculating the second-stage exhaust superheat Tsh4 is to obtain the second-stage exhaust pressure P4 and the second-stage exhaust temperature T4, and then obtain the saturation temperature Tp4 corresponding to the second-stage exhaust pressure P4 using the second-stage exhaust pressure P4, and then the second-stage exhaust superheat Tsh4 = T4 - Tp4.

[0077] In some embodiments of the present disclosure, when the control module energy adjusts and controls the gas make-up valve 6, the control module obtains the second-stage intake pressure P3' at the second-stage intake port and determines whether the second-stage intake pressure P3' reaches the current target second-stage intake pressure value Pmth; if the second-stage intake pressure P3' does not reach the current target intake pressure value Pmth, the control module controls the opening degree of the gas make-up valve 6 to be larger or smaller, so that the second-stage intake pressure P3' reaches the current target intake pressure value Pmth.

[0078] After adjusting the gas supply valve 6 to the first opening, the second-stage intake superheat Tsh3' and the second-stage exhaust superheat Tsh4 are compared with the preset range, and the gas supply valve 6 is adjusted again based on the comparison result to avoid the risk of gas supply zone liquidation.

[0079] Some embodiments of the second aspect of the present disclosure provide a heating device including a two-stage compression centrifugal device.

[0080] Although the alternative embodiments of the present disclosure have been described in detail above with reference to the drawings, the embodiments of the present disclosure are not limited to the specific details of the above embodiments. Within the technical concept of the embodiments of the present disclosure, various simple modifications can be made to the technical solutions of the embodiments of the present disclosure, and all of these simple modifications belong to the protection scope of the embodiments of the present disclosure.

[0081] Furthermore, it should be noted that the specific technical features described in the above embodiments can be combined in any appropriate manner if not contradictory, and in order to avoid unnecessary repetition, the embodiments of the present disclosure do not specifically describe various possible combination methods.

[0082] The above are merely some specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto, and any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope of the disclosure of the present disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be in accordance with the scope of protection of the claims. [Explanation of symbols]

[0083] 100 Two-stage compression centrifugal device, 1 intake pipe, 11 first pressure sensor, 12 first temperature sensor, 2 Two-stage centrifugal compressor, 3 connecting pipe, 31 second pressure sensor, 32 second temperature sensor, 4 exhaust pipe, 41 third pressure sensor, 42 third temperature sensor, 5 condenser, 6 gas supply valve, 61 fourth pressure sensor, 62 fourth temperature sensor, 7 economizer, 8 evaporator, 9 fifth pressure sensor, 10 Single-stage throttle valve, 13 sixth pressure sensor, 14 Two-stage throttle valve.

Claims

1. A two-stage compression centrifugal device, a two-stage centrifugal compressor; an evaporator and a condenser; an economizer and a gas make-up valve; a calculation module; a first-stage intake port of the two-stage centrifugal compressor connected to an exhaust port of the evaporator, and a second-stage exhaust port of the two-stage centrifugal compressor connected to an intake port of the condenser; The economizer is connected between the intake port of the evaporator and the exhaust port of the condenser, and the economizer is connected to a first-stage exhaust port and a second-stage intake port of the two-stage centrifugal compressor, respectively, by the gas make-up valve; The two-stage compression centrifugal device, characterized in that the calculation module calculates an actual gas replenishment amount and an optimal gas replenishment amount based on operating parameters of the two-stage compression centrifugal device in order to adjust the opening degree of the gas replenishment valve.

2. The calculation module calculates the actual gas replenishment amount δm according to the following formula: [0012] m １ : refrigerant mass in one-stage circulation compression of a two-stage centrifugal compressor, W ｃｏｍｐ :input power of two-stage centrifugal compressor, Q ｌｏｓｓ : total heat exchange amount of two-stage centrifugal compressor, h ０［１］ : enthalpy value of the first stage intake, h ０［３］ :Gas supply valve enthalpy value, h ０［３´］ : Enthalpy value of the two-stage intake, h ０［４］ : enthalpy value of the second-stage exhaust port, h ０［５］ : condenser enthalpy value, h ０［７］ 2. The two-stage compression centrifugal device according to claim 1, wherein: is an outlet enthalpy value of the economizer.

3. The calculation module calculates the optimal gas replenishment amount Tδm based on the following formula: [0013] m １ : refrigerant mass in one-stage circulation compression of a two-stage centrifugal compressor, W ｃｏｍｐ :input power of two-stage centrifugal compressor, Q ｌｏｓｓ : total heat exchange amount of two-stage centrifugal compressor, h ０［１］ : enthalpy value of the first stage intake, h ０［３］ :Gas supply valve enthalpy value, h ０［３´´］ : enthalpy value of the optimal two-stage intake, h ０［４］ : enthalpy value of the second-stage exhaust port, h ０［５］ : condenser enthalpy value, h ０［７］ 2. The two-stage compression centrifugal device according to claim 1, wherein: is an outlet enthalpy value of the economizer.

4. The operating parameters include a temperature parameter and a pressure parameter, and the calculation module refers to a temperature, pressure and enthalpy value comparison table and / or a pressure and saturation enthalpy value comparison table based on the temperature parameter and the pressure parameter, and calculates h ０［１］ , h ０［３］ , h ０［３´］ , h ０［３´´］ , h ０［４］ , h ０［５］ , h ０［７］ 4. The two-stage compression centrifugal device according to claim 2, wherein the pressure is obtained by:

5. further comprising a control module; 2. The two-stage compression centrifugal device according to claim 1, wherein the control module adjusts the opening degree of the gas supply valve based on the optimum gas supply amount as a control target and the actual gas supply amount as a feedback amount.

6. 6. A method for controlling intermediate gas replenishment in a two-stage compression centrifugal device, which is carried out by the two-stage compression centrifugal device according to any one of claims 1 to 5, comprising: receiving operating parameters of the two-stage compression centrifugal device; A method for controlling intermediate gas replenishment in a two-stage compression centrifugal device, comprising: calculating an optimum gas replenishment amount and an actual gas replenishment amount based on operating parameters of the two-stage compression centrifugal device in order to adjust the opening degree of the gas replenishment valve. [Request Item 7] [Number 14] The actual gas replenishment amount δm is calculated by m １ : refrigerant mass in one-stage circulation compression of a two-stage centrifugal compressor, W ｃｏｍｐ :input power of two-stage centrifugal compressor, Q ｌｏｓｓ : total heat exchange amount of two-stage centrifugal compressor, h ０［１］ : enthalpy value of the first stage intake, h ０［３］ :Gas supply valve enthalpy value, h ０［３´］ : Enthalpy value of the two-stage intake, h ０［４］ : enthalpy value of the second-stage exhaust port, h ０［５］ : condenser enthalpy value, h ０［７］ 7. The method for controlling intermediate gas replenishment in a two-stage compression centrifugal unit according to claim 6, wherein: is an outlet enthalpy value of the economizer. [Request Item 8] [Number 15] The optimum gas replenishment amount Tδm is calculated by m １ : refrigerant mass in one-stage circulation compression of a two-stage centrifugal compressor, W ｃｏｍｐ :input power of two-stage centrifugal compressor, Q ｌｏｓｓ : total heat exchange amount of two-stage centrifugal compressor, h ０［１］ : enthalpy value of the first stage intake, h ０［３］ :Gas supply valve enthalpy value, h ０［３´´］ : enthalpy value of the optimal two-stage intake, h ０［４］ : enthalpy value of the second-stage exhaust port, h ０［５］ : condenser enthalpy value, h ０［７］ 7. The method for controlling intermediate gas replenishment in a two-stage compression centrifugal unit according to claim 6, wherein: is an outlet enthalpy value of the economizer.

9. 7. The method for controlling intermediate gas replenishment of a two-stage compression centrifugal device according to claim 6, further comprising: setting the optimum gas replenishment amount as a control target, setting the actual gas replenishment amount as a feedback amount, and adjusting the opening degree of the gas replenishment valve to a first opening degree.

10. Obtaining two-stage intake superheat at the two-stage intake; determining whether the two-stage intake superheat is within a preset range; maintaining the gas supply valve at the first opening degree based on the two-stage intake superheat being within the preset range; controlling the first opening degree to reduce the opening degree based on the fact that the two-stage intake superheat is less than a predetermined intake superheat lower limit value; 10. The method for controlling intermediate gas replenishment of a two-stage compression centrifugal machine according to claim 9, further comprising: energy adjusting and controlling the first opening degree based on the second-stage intake superheat being greater than a preset intake superheat upper limit value.

11. Obtaining second-stage exhaust superheat at the second-stage exhaust port; determining whether the second-stage exhaust superheat is within a preset range; maintaining the gas replenishment valve at the first opening degree based on the second-stage exhaust superheat being within the preset range; controlling the first opening degree to reduce the opening degree based on the fact that the second-stage exhaust superheat is less than a preset exhaust superheat lower limit value; 10. The method for controlling intermediate gas replenishment of a two-stage compression centrifugal device according to claim 9, further comprising: energy adjusting and controlling the first opening degree based on the second-stage exhaust superheat being greater than a preset exhaust superheat upper limit value.

12. A heating device, comprising: A heating system comprising the two-stage compression centrifugal device according to any one of claims 1 to 5.

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