Refrigerating System, Method for Controlling Refrigerating System, and Storage Medium

This application claims benefit of Chinese Patent Application No. 202410330166.3, filed Mar. 21, 2024, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.

This application relates to the field of refrigerating systems, and specifically to a refrigerating system, a method for controlling a refrigerating system, and a computer-readable storage medium.

Described herein is a refrigerating system, a method for controlling a refrigerating system, and a computer-readable storage medium, so as to at least solve or alleviate some of the problems of existing refrigerating systems.

A first aspect of this application provides a refrigerating system, including a compressor, a condenser, an economizer, an evaporator, a first throttling device and a second throttling device. The compressor has a discharge port, a first suction port, and a second suction port. An inlet of the condenser is in communication with the discharge port of the compressor. An outlet of the evaporator is in communication with the first suction port of the compressor. An inlet of the economizer is in communication with an outlet of the condenser, a gas outlet of the economizer is in communication with the second suction port of the compressor, and a liquid outlet of the economizer is in communication with an inlet of the evaporator. The first throttling device is provided on a pipe connecting the condenser and the economizer. The second throttling device is provided on a pipe connecting the economizer and the evaporator.

The refrigerating system further includes a first throttling device control mode setting module and a first throttling device control module. The first throttling device control mode setting module receives at least one parameter associated with operation of the compressor, determines whether the at least one parameter indicates that the compressor is under a preset surge protection condition, and selects between a normal control mode and a surge protection control mode based on the determination. The first throttling device control module controls the first throttling device in the normal control mode in response to the first throttling device control mode setting module selecting the normal control mode, and controls the first throttling device in the surge protection control mode in response to the first throttling device control mode setting module selecting the surge protection control mode.

In one or more embodiments of the refrigerating system, the condenser is provided with a first liquid level sensor configured to detect a current liquid level of the condenser. In the normal control mode, the first throttling device control module receives current liquid level information of the condenser sent by the first liquid level sensor, and controls an open degree of the first throttling device based on a comparison result between the current liquid level of the condenser and a target liquid level of the condenser.

In one or more embodiments of the refrigerating system, in the surge protection control mode, the first throttling device control module controls an open degree of the first throttling device to increase a refrigerant gas suction amount of the second suction port.

In one or more embodiments the refrigerating system, when switching from the normal control mode to the surge protection control mode, the first throttling device control module controls the open degree of the first throttling device to increase.

In one or more embodiments of the refrigerating system, the at least one parameter includes a lift of the refrigerating system.

In one or more embodiments of the refrigerating system, the first throttling device control mode setting module selects the surge protection control mode when the lift of the refrigerating system is greater than a threshold.

In one or more embodiments of the refrigerating system, the economizer is provided with a second liquid level sensor configured to detect a current liquid level of the economizer. The refrigerating system further includes a second throttling device control module that receives current liquid level information of the economizer sent by the second liquid level sensor, and controls an open degree of the second throttling device based on a comparison result between the current liquid level information of the economizer and a target liquid level of the economizer.

In one or more embodiments of the refrigerating system, the first throttling device and/or the second throttling device is an electric butterfly valve.

A second aspect of this application provides a method for controlling a refrigerating system. The refrigerating system includes a compressor, a condenser, an economizer, an evaporator, a first throttling device and a second throttling device. The compressor has a discharge port, a first suction port, and a second suction port. An inlet of the condenser is in communication with the discharge port of the compressor. An outlet of the evaporator is in communication with the first suction port of the compressor. An inlet of the economizer is in communication with an outlet of the condenser, a gas outlet of the economizer is in communication with the second suction port of the compressor, and a liquid outlet of the economizer is in communication with an inlet of the evaporator. The first throttling device is provided on a pipe connecting the condenser and the economizer. The second throttling device is provided on a pipe connecting the economizer and the evaporator. The method includes: a step of receiving at least one parameter associated with operation of the compressor; a step of determining whether the at least one parameter indicates that the compressor is under a preset surge protection condition; a step of selecting between a normal control mode and a surge protection control mode based on the determination; a step of controlling the first throttling device in the normal control mode in response to selecting the normal control mode; and a step of controlling the first throttling device in the surge protection control mode in response to selecting the surge protection control mode.

In the method for controlling a refrigerating system, in the step of “controlling the first throttling device in the normal control mode”, an open degree of the first throttling device is controlled based on a comparison result between the current liquid level information of the condenser and a target liquid level of the condenser. In the step of “controlling the first throttling device in the surge protection control mode”, the open degree of the first throttling device is controlled to increase a refrigerant gas suction amount of the second suction port.

In the method for controlling a refrigerating system, in the step of “controlling the first throttling device in the surge protection control mode”, when switching from the normal control mode to the surge protection control mode, the open degree of the first throttling device is controlled to increase.

The method for controlling a refrigerating system, further includes a step of controlling an open degree of the second throttling device based on a comparison result between the current liquid level information of the economizer and a target liquid level of the economizer.

A third aspect of this application provides a computer-readable storage medium storing a processor-readable instruction, in which the processor-readable instruction is executed by a processor to perform the method for controlling a refrigerating system according to any one of the above embodiments.

First, it should be noted that compositions, working principles, characteristics, advantages, and the like of a refrigerating system, a method for controlling a refrigerating system and a computer-readable storage medium according to this application will be described below in an illustrative manner. However, it should be understood that all descriptions are given for illustrative purposes only and should not be construed as any limitation to this application.

In addition, for any single technical feature described or implicit in the embodiments mentioned herein, or any single technical feature illustrated or implicit in the drawings, this application still allows any combination or deletion between these technical features (or their equivalents) without any technical obstacles, thereby obtaining other embodiments of this application that may not be directly mentioned herein.

In refrigerating systems, there is a need to control liquid levels in a condenser and an economizer, and prevent a compressor from surging. Existing systems have a problem of poor control accuracy or high manufacturing cost due to complex structures. According to the refrigerating system, the method for controlling a refrigerating system and the computer-readable storage medium of this application, a demand for surge protection of a compressor is met with a solution that is relatively simple in structure and low in cost.

shows a refrigerating systemaccording to one or more embodiments of this application. The refrigerating systemincludes a compressor, a condenser, an economizerand an evaporatorconnected by a refrigerant circulation pipe. The compressorhas a discharge port, a second suction portand a first suction port. An inletof the condenseris in communication with the discharge portof the compressor. An inletof the economizeris in communication with an outletof the condenser, and a gas outletof the economizeris in communication with the second suction portof the compressor. An inletof the evaporatoris in communication with a liquid outletof the economizer, and an outletof the evaporatoris in communication with the first suction portof the compressor. A first throttling deviceis provided on a pipe connecting the condenserand the economizer. A second throttling deviceis provided on a pipe connecting the economizerand the evaporator.

Types and specifications of the compressor, the condenser, the economizerand the evaporatormay be appropriately selected from the types and specifications known in the art. As a specific example, the compressoris a centrifugal compressor. The condenserand the evaporatorare both shell-and-tube heat exchangers, with the refrigerant passing through the shell side and a working fluid passing through the tube side. The economizeris a flash evaporator.

Referring toand, the refrigerating systemfurther includes a first throttling device control mode setting moduleand a first throttling device control module.

The first throttling device control mode setting modulereceives at least one parameter associated with operation of the compressor, determines whether the at least one parameter indicates that the compressoris under a preset surge protection condition, and selects between a normal control mode and a surge protection control mode based on the determination. The first throttling device control modulecontrols an open degree of the first throttling devicein the normal control mode in response to the first throttling device control mode setting moduleselecting the normal control mode, and controls the open degree of the first throttling devicein the surge protection control mode in response to the first throttling device control mode setting moduleselecting the surge protection control mode.

In one or more embodiments, referring to, the at least one parameter includes a lift of the refrigerating system. Corresponding to a respective system loading rate, when the lift of the refrigerating systemis greater than a threshold (the gray area in), it means that at this lift, the compressorwill be affected by surge or the compressorhas been affected by surge. At this time, the first throttling device control mode setting moduleselects the surge protection control mode, and the first throttling device control modulecontrols the first throttling devicein the surge protection control mode in response to the selection of the first throttling device control mode setting module, specifically adjusting and increasing an open degree of the first throttling deviceso as to appropriately increase the amount of refrigerant entering the economizer. When other working conditions of the condenser(such as entering water temperature and entering water amount or entering air temperature and entering air amount) remain unchanged, more refrigerant will flow into the economizerand then can enter the second suction portof the compressor in a state of refrigerant gas after being vaporized in the economizer, thereby increasing an air intake flow of the compressorto avoid surge. Similarly, corresponding to a respective system loading rate, when the lift of the refrigerating systemis less than a threshold (the black area in), it means that at this lift, the compressoris not easily affected by surge. At this time, the first throttling device control mode setting moduleselects the normal control mode, and the first throttling device control modulecontrols the first throttling devicein the normal control mode in response to the selection of the first throttling device control mode setting module.

It should be noted that the “threshold” mentioned above is based on the system loading at the moment of obtaining the “lift of the refrigerating system”. In some embodiments, the “threshold” under different system loadings may be different.

In some embodiments, the at least one parameter received by the first throttling device control mode setting modulemay further includes a detection result of a surge detector provided in the compressor. When the detection result is greater than a threshold, it indicates that the compressoris under the preset surge protection condition, so the first throttling device control mode setting moduleselects the surge protection control mode.

In some embodiments, the at least one parameter received by the first throttling device control mode setting modulemay further includes a working point of the compressor. When the working point of the compressoris close to a surge area of the compressor, it indicates that the compressoris under the preset surge protection condition, so the first throttling device control mode setting moduleselects the surge protection control mode.

In some embodiments, the first throttling device control mode setting modulehas two outputs, namely, an output for selecting the normal control mode and an output for selecting the surge protection mode.

In some embodiments, the first throttling device control mode setting modulehas three outputs, namely, an output for selecting the surge protection mode, an output for selecting the normal control mode and an output for selecting a balance control mode. That is, the first throttling device control mode setting modulecan generate a variety of different outputs through multiple decision logics, and send the outputs to the first throttling device control module.

In some embodiments, the condenseris provided with a first liquid level sensorconfigured to detect a current liquid level of the condenserand send current liquid level information of the condenserto the first throttling device control module. In the normal control mode, the first throttling device control modulecontrols the open degree of the first throttling devicebased on a comparison result between the current liquid level information of the condenserand a target liquid level of the condenser.

By controlling the open degree of the first throttling deviceprovided downstream of the condenser, the liquid level of the condensercan be controlled to be closer to the position or area of the target liquid level. In this way, the liquid level of the condensercan be optimized, so that a load of the condensercan be quickly adjusted to better respond to changes in working conditions and properties of the refrigerating systemcan be balanced. In addition, by receiving the current liquid level information of the condenser, when the first throttling devicefails, the failure of the first throttling devicecan be identified by discovering an abnormality of the current liquid level information of the condenser.

The first liquid level sensormay be selected from a variety of types of sensors such as a float-type liquid level sensor, a pressure-type liquid level sensor, and a capacitance-type liquid level sensor. In some embodiments, selecting a capacitance-type liquid level sensor as the first liquid level sensoris beneficial for rapid and reliable liquid level detection for refrigerants with different characteristics.

A method for comparing the current liquid level information of the condenserand the target liquid level of the condenser, as well as a method for controlling the first throttling device, can be set according to needs.

For example, when the current liquid level information of the condenserindicates that the current liquid level of the condenseris lower than the target liquid level of the condenser, the open degree of the first throttling deviceis reduced. When the current liquid level information of the condenserindicates that the current liquid level of the condenseris higher than the target liquid level of the condenser, the open degree of the first throttling deviceis increased.

For another example, when the current liquid level information of the condenserindicates that the current liquid level of the condenseris lower than the target liquid level of the condenser, and a difference between the current liquid level of the condenserand the target liquid level of the condenseris greater than a threshold, the open degree of the first throttling deviceis reduced. When the current liquid level information of the condenserindicates that the current liquid level of the condenseris higher than the target liquid level of the condenser, and the difference between the current liquid level of the condenserand the target liquid level of the condenseris greater than a threshold, the open degree of the first throttling deviceis increased.

Although in some embodiments, in the normal control mode, the first throttling device control moduleadjusts the first throttling devicebased on the purpose of controlling the liquid level height of the condenser, this application is not limited thereto. For example, in some embodiments, in the normal control mode, the first throttling device control moduleadjusts the first throttling devicebased on a purpose of controlling a saturation temperature of the evaporator. In some embodiments, in the normal control mode, the first throttling device control moduleadjusts the first throttling devicebased on a purpose of balancing liquid levels of the condenserand the economizer.

In some embodiments, in the surge protection control mode, the first throttling device control modulecontrols the open degree of the first throttling deviceto increase a refrigerant gas suction amount of the second suction port.

In some embodiments, when switching from the normal control mode to the surge protection control mode, the first throttling device control modulecontrols and increases the open degree of the first throttling device. In this way, the refrigerant gas suction amount of the second suction portcan be increased to protect the compressorfrom further surge.

It should be noted that, in order to increase the refrigerant gas suction amount of the second suction portof the compressor, the first throttling deviceis generally controlled by increasing the open degree of the first throttling device. Of course, depending on the original state of the first throttling device, the first throttling devicecan be adjusted by maintaining the open degree of the first throttling devicewhile, for example, reducing the load of the compressor, or by making the open degree of the first throttling devicelarger than the normal open degree required, or the first throttling deviceand the second throttling devicecan be adjusted in conjunction. In other words, the first throttling deviceis controlled based on the purpose of increasing the refrigerant gas suction amount of the second suction portof the compressor, and the specific control method can be carried out according to actual conditions.

By the surge protection control mode, the first throttling devicecan be used to easily implement surge protection for the compressor, and there is no need to separately provide pipeline equipment such as a hot gas bypass valve. The structure of the refrigerating systemwill be simplified, thereby reducing failure rate and production cost of the refrigerating system.

In some embodiments, in the surge protection control mode, the first throttling deviceis maintained at a fixed and large open degree to simplify a control logic of a surge protection control mode.

In some embodiments, in the surge protection control mode, the first throttling deviceis maintained within a large open degree range to take into account other control purposes such as controlling the liquid level of the condenser.

In some embodiments, the economizeris provided with a second liquid level sensorconfigured to detect a current liquid level of the economizer. The refrigerating systemfurther includes a second throttling device control modulethat receives current liquid level information of the economizersent by the second liquid level sensor, and controls an open degree of the second throttling devicebased on a comparison result between the current liquid level information of the economizerand a target liquid level of the economizer.

By controlling the open degree of the second throttling deviceprovided downstream of the economizer, the liquid level of the economizercan be controlled to be closer to the position or area of the target liquid level. In this way, the liquid level of the economizercan be optimized, so that properties of the refrigerating systemcan be better balanced. In addition, by receiving the current liquid level information of the economizer, when the second throttling devicefails, the failure of the second throttling devicecan be identified by discovering an abnormality of the current liquid level information of the economizer.

The second liquid level sensormay be selected from a variety of types of sensors such as a float-type liquid level sensor, a pressure-type liquid level sensor, and a capacitance-type liquid level sensor. In some embodiments, as the second liquid level sensor, a liquid level sensor of the same type as the first liquid level sensoris selected.

A method for comparing the current liquid level information of the economizerand the target liquid level of the economizer, as well as a method for controlling the second throttling device, can be set by referring to the method for comparing the current liquid level information of the condenserand the target liquid level of the condenser, as well as the method for controlling the first throttling devicedescribed above, and will not be repeated here.

In some embodiments, the second throttling device control modulecontrols the second throttling devicein a single control mode.

In some embodiments, the second throttling device control modulecontrols the second throttling deviceby switching between a plurality of control modes.