JP2006515924A - System and method for gradually changing the capacity of a refrigeration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control system for generating an output capability in separate stages in a refrigeration system (100).
The refrigeration system (100) is preferably a multi-evaporator system having two or more multi-capacity compressors (102, 104). The multi-capacity compressor (102, 104) may be any type of reciprocating compressor or scroll compressor that can provide two or more different output capacities. The contribution of the compressors (102, 104) to the overall capacity of the system may be equal or more preferably not equal, i.e. the capacity of one compressor may be greater than the other compressor. The control system generates the stepped capacity of the refrigeration system (100) by shaping and controlling the operation of the compressors (102, 104) and the output capabilities provided by these compressors (102, 104).

Description

This application claims the benefit of US Provisional Patent Application No. 60 / 442,215, filed Jan. 24, 2003.
The present invention generally relates to a refrigeration system with stepped output capability. More particularly, the present invention relates to a control system that can provide eight or more output capacities for a refrigeration system having two or more multi-capacity compressors.

  Two-capacity compressors have been used to provide various levels of output capability. One drawback to using a two-capacity compressor is that the refrigeration system requires a different output capability than one of the compressor capacities, which, on the one hand, creates extra capacity depending on the compressor configuration selected. Or, on the other hand, the ability is insufficient.

In addition, by controlling the operation of multiple single capacity compressors incorporated into the refrigeration system, various levels of output capacity can be obtained for the refrigeration system. One such system is discussed in US Pat. No. 4,384,462 (hereinafter referred to as the '462 patent). The '462 patent relates to a multi-compressor refrigeration system in which multiple compressors and multiple evaporators of the same capacity are provided in different enclosures connected to the compressor. These compressors have a single capability and can be switched between an “on” state and a “off” state. By switching the compressor between “on” and “off” states in various combinations, 2 ^N different levels or operating states are obtained for the refrigeration system. These include the zero state where all compressors are in the “cut” state. The control device can increase or decrease a specific operating state of the refrigeration system in response to an increase or decrease in the suction pressure of the system.
Further, for refrigeration systems, various levels of output capability can be obtained by sequentially changing the operation of a number of two-capacity compressors incorporated in the refrigeration system. One such system is discussed in US Pat. No. 4,501,125 (hereinafter referred to as the '125 patent). The '125 patent relates to a temperature control system. The temperature control system may include two two-stage compressors connected to the evaporator with a refrigeration circuit. The '125 patent argues that if two two-stage compressors are used, four cooling stages can be utilized. The system increases or decreases the stage or cooling (or heating) state according to predetermined criteria in the look-up table. U.S. Pat. No. 4,501,125

  Therefore, there is a need for a system and method that provides staged output capability for a refrigeration system having two or more multi-capacity compressors in order to provide adequate output capability to meet the specific output capability required by the refrigeration system. Has been.

  One embodiment of the invention relates to a refrigeration system having a plurality of compressors. Each compressor of the plurality of compressors is configured to provide a plurality of separate output capabilities. The refrigeration system further includes a condenser in fluid communication with the plurality of compressors and at least one evaporator in fluid communication with the condenser and the plurality of compressors. A control system is used to control the operation (start or stop) of each compressor of the plurality of compressors and to control a separate output capability of the plurality of separate output capabilities of each compressor of the plurality of compressors. . The control system determines the operation of the compressor and the separate output capacity of each operating compressor of the plurality of compressors depending on the required output capacity of the refrigeration system.

  Another embodiment of the invention relates to a method for controlling the operation of multiple multi-compressor compressors in a refrigeration system having at least one evaporator. The method includes determining the amount of output capability required by the refrigeration system, determining a plurality of multi-capacity compressor configurations to generate the determined amount of output capability. The determined configuration of the multi-capacity compressor is obtained from a table that lists a plurality of compressor operating configurations and compressor capacities for a plurality of multi-capacity compressors. Each of the plurality of features corresponds to the output capacity of the refrigeration system. The method further includes applying a determined configuration of the plurality of multi-capacity compressors to the plurality of multi-capacity compressors to generate a determined amount of output capacity in the refrigeration system.

  Yet another embodiment of the present invention provides a required output for a plurality of compressors, a condenser in fluid communication with the plurality of compressors, at least one evaporator in fluid communication with the condenser and the plurality of compressors, and a refrigeration system. The present invention relates to a refrigeration system having a control system that controls a plurality of compressors in accordance with the capacity. The plurality of compressors has a plurality of predetermined actuation features, and each predetermined actuation feature of the plurality of predetermined actuation features provides a predetermined output capability for the refrigeration system. The control system is configured to select a predetermined operating feature that most efficiently satisfies the required output capability from a plurality of predetermined operating features. Each compressor of the plurality of compressors has a plurality of separate output capacities, and each predetermined operating configuration for the plurality of compressors has an operating state and an operation for each compressor of the plurality of compressors. A separate output capability for each compressor is included.

  Another embodiment of the invention relates to a method for controlling the operation of multiple multi-compressor compressors in a refrigeration system. The method provides a refrigeration system having a plurality of multi-capacity compressors, condensers, and a plurality of evaporators connected in a closed refrigeration circuit, and determining the amount of output capacity the refrigeration system requires The process of carrying out is included. The method further includes determining a plurality of multi-capacity compressor features having a predetermined output capability to meet the determined amount of required output capability. Each of the multi-capacity compressors has a plurality of separate output capacities, and the determined form of the multi-capacity compressors includes an operating state for each of the multi-capacity compressors. And a separate output capability for each multi-capacity compressor operating. The method further includes generating a control command corresponding to the determined configuration of the plurality of multi-capacity compressors, controlling the plurality of multi-capacity compressors, and generating a predetermined output capability for the refrigeration system. .

  Another advantage of the present invention is that it more closely matches the output capacity required by the refrigeration system, thus providing a variety of output capabilities, thereby avoiding generating extra capacity that is not used. That's what it means.

Other features and advantages of the present invention will become apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

  An entire system to which the present invention can be applied is shown as an example in FIG. As shown, a heating, ventilation, and air conditioning (HVAC) or refrigeration system 100 includes a first compressor 102, a second compressor 104, a condenser 106, one or more evaporators 108, an expansion device 110, and a control. A board 140 is included. The control board 140 includes an analog / digital (A / D) converter, a microprocessor, a nonvolatile memory, and an interface board. The operation of the control panel 140 will be described in detail below. The conventional refrigeration system or HVAC system 100 includes many other features not shown in FIG. These features have been omitted for the purpose of simplifying the drawing for ease of illustration.

  In the refrigeration system 100, the compressors 102 and 104 compress the refrigerant vapor and deliver the compressor refrigerant vapor to the condenser 106 through a single line. The outputs of the compressors 102 and 104 are coupled together so that the compressed refrigerant vapor from each of the compressors 102 and 104 is combined into a single line and then conveyed to the condenser 106. Further, when only one of the compressors 102 and 104 is operating, the output of the other compressor 102 and 104 is closed or sealed with a valve (not shown) and passed through the non-operating compressors 102 and 104. Prevent the refrigerant from flowing backward. The compressors 102 and 104 are preferably any type of reciprocating or scrolling compressor with multi-stage capability output, i.e. two or more distinct output capability levels. However, it should be understood that the present invention can be used with any type of compressor that can be configured to provide two or more separate output capabilities.

  In another embodiment of the present invention, the compressed refrigerant vapor output from each of the compressors 102 and 104 may be conveyed separately and may be separate until the refrigerant vapor output is combined at the condenser 106. In yet another embodiment of the invention, the compressed refrigerant vapor output from each of the compressors 102 and 104 may be conveyed in a separate refrigerant circuit. That is, when refrigerant is circulated through the system, the compressed refrigerant vapor from one compressor is not mixed with the compressed refrigerant vapor from the other compressor. In this embodiment, each circuit's condenser and evaporator may have any suitable configuration that allows the necessary heat exchange while maintaining separate refrigerant circuits.

  In FIG. 1, refrigerant vapor from compressors 102 and 104 flows through or around the heat exchanger coil of condenser 106 and enters a heat exchange relationship with a fluid, preferably air or water. The refrigerant vapor changes its phase into a refrigerant liquid in the condenser 106 as a result of the heat exchange relationship with the fluid. The condensed liquid refrigerant flows from the condenser 106 through the expansion device 110 into the evaporator 108. The expansion device 110 may be any type of suitable device, such as an expansion valve or capillary, that can convert high pressure liquid to low pressure liquid and vapor.

  The output of the expansion device 110 is then provided to one or more evaporators 108 depending on the particular configuration of the refrigeration system 100. One or more evaporators 108 may be shut off or deactivated (discussed in detail below) depending on the specific cooling requirements of the refrigeration system 100 or the required power capability. . Refrigerant liquid and / or vapor is prevented from entering the inactive evaporator 108 by valves (not shown) provided at the respective inlets and outlets of the inactive evaporator 108. In another embodiment of the invention, the line from the expansion device 110 may be connected to a manifold with appropriate valves connected to each of the evaporators 108. In this case, the manifold can be configured or operated to provide refrigerant to a suitable evaporator 108. Similarly, the output of the evaporator 108 may be connected to the manifold by a suitable valve. The manifold can in this case be configured or actuated to provide refrigerant vapor to the compressors 102 and 104 using only one line. Deactivation of the evaporator 108 and valve closure can be controlled individually by the central control system or by each of the evaporators 108, whether in separate lines or in the manifold.

  Refrigerant liquid and vapor flow from the expansion device 110 through or around each heat exchange coil of the activated evaporator 108 and enter a heat exchange relationship with the fluid, preferably air, to lower the temperature of the air. As a result of the heat exchange relationship with the air, the refrigerant liquid changes its phase into refrigerant vapor in the evaporator 108. The vapor refrigerant in the evaporator 108 exits the evaporator 108 through the suction connection and returns to the compressors 102 and 104 via a common line to complete the cycle. The number of evaporators 108 in the refrigeration system 100 can vary from 1 to N. Here, N is preferably a number that matches the maximum number of stepped outputs from compressors 102 and 104 (described in detail below). However, in another embodiment of the present invention, the number of evaporators may be greater than the number of stepped outputs from compressors 102 and 104, ie, N may be greater than the maximum number of stepped outputs. In this embodiment, the evaporator output does not match the compressor output, unlike the embodiment where the number of staged outputs and the number of evaporators are the same. For example, if both compressors 102 and 104 in FIG. 1 are two-capacity compressors, N is preferably eight (see FIG. 2) and eight (or more) evaporators 108 are connected to the refrigeration system 100. Can be provided.

  In other embodiments of the present invention, the number of compressors 102 and 104 may be increased to increase the total number of power capacity stages available in refrigeration system 100, and / or the capacity each of compressors 102 and 104 provides. May be increased (described in detail below). Correspondingly, increasing the number of power capability stages increases the preferred number (N) of evaporators 108 that can be used in the refrigeration system 100 and maintains a favorable ratio of one evaporator to one power capability stage. .

  The control panel 140 includes an A / D converter that receives an input signal indicating the performance of the system 100 from the system 100. The control board 140 further includes an interface board for transmitting signals to the components of the system 100 and controlling the operation of the system 100. For example, the control panel 140 can transmit signals to control the number of operating states and to control the operation of the compressors 102 and 104. The control board 140 may further include many other features and components not discussed herein. These features and components are omitted for the purpose of facilitating the description of the control panel 140.

  The control board 140 uses control algorithms or software to control the operation of the system 100 and to determine and execute the operating configuration of the compressors 102 and 104 depending on the specific output capability required for the system 100. Part of the control system. In addition, the control system may use a control algorithm that opens and closes the valve and engages or activates the evaporator 108 and disengages or deactivates it. In one embodiment, the control algorithm may be a computer program or software stored in the non-volatile memory of the control board 140 and may include a series of instructions that can be executed by the microprocessor of the control board 140. Although it is preferred that the control algorithm be embodied in a computer program and executed by a microprocessor, it is understood that those skilled in the art may implement the control algorithm using digital and / or analog hardware. Should be. When the control algorithm is executed using hardware, the corresponding configuration of the control panel 140 is modified to incorporate the necessary components and remove components that are no longer needed.

  The control system of the present invention controls the output of the refrigeration system 100 by controlling which compressors 102 and 104 are activated at specific times and by controlling the output capability of the compressors 102 and 104 that are operating. Generate various stages of ability. The control system of the present invention can generate various output capability stages for the refrigeration system 100 by controlling the operation of the compressors and the output capabilities of these compressors. The operating configuration of the compressors 102 and 104 of FIG. 1 to obtain eight separate stages is shown in FIG. The compressors 102 and 104 in FIG. 1 are two-capacity compressors having a first stage that provides half of the total output capacity of the compressors 102 and 104 and a second stage that provides the total output capacity of the compressors 102 and 104. As can be seen in FIG. 2, by operating one of the compressors 102 and 104 in one of the two modes of operation of these compressors, four distinct stages are generated or obtained. The other four stages are generated or obtained by operating both compressors 102 and 104 in one of their two modes of operation. It should be understood that the particular configuration of compressors 102 and 104 can be correlated with any particular stage, and the correlation shown in FIGS. 2 and 3 is merely exemplary. However, these stages are preferably identified sequentially in order of increasing system capacity.

  When additional compressors are added to the refrigeration system 100, the control system of the present invention (and the control chart of FIG. 2) is increased, providing additional control features for the new compressors. For example, by adding a new compressor, a new stage can be generated for the first stage output and the second stage output of the new compressor, and the new compressor output can be combined with the output of one or both of the compressors 102 and 104 New stages can be generated. Similarly, if one of the compressors 102 and 104 is replaced with a multi-capacity compressor with three or more separate output capacities, the control system of the present invention (and the control chart in FIG. 2) becomes larger and the new compressor capacities are increased. Provide additional control features.

  To further illustrate the operation of the control system of the present invention, the output capability stage of FIG. 2 is applied to several separate compressors 102 and 104 configurations. FIG. 3 shows the output capability of each of the eight stages for four different compressor configurations. Four different compressor configurations include configurations in which one compressor provides 40% of the total system capacity and the other compressor provides 60% of the total system capacity, such as a 2t capacity compressor and a 3t capacity compressor configuration. , One compressor provides 30% of the total system capacity and the other compressor provides 70% of the total system capacity, eg, a 1 t capacity compressor and a 2/3 t capacity compressor configuration, Features in which the compressor provides 20% of the total system capacity and the other compressor provides 80% of the total system capacity, for example, a 1t capacity compressor and a 4t capacity compressor form, and each compressor is 50% of the total system capacity. % Providing features, eg a pair of 2t Include the form of the capacity of the compressor.

  As can be seen in FIG. 3, when compressors 102 and 104 having different capacities are used in the control system of the present invention, eight different output capacities are generated by eight stages or configurations. However, if the output capacities of the compressors 102 and 104 are the same, only four different output capacities are generated by the eight stages or configurations. This is because some of the stages generate the same output capability. Thus, in the preferred embodiment of the present invention, compressors 102 and 104 have different output capabilities in order to maximize the number of output capability stages. The determination and selection of the specific total output capacity of the compressors 102 and 104 is made based on the maximum and minimum requirements of the refrigeration system 100 and based on the specific output capacity desired by the user.

  6 illustrates a process for determining an appropriate power capability for refrigeration system 100. The process begins at step 402. In this step, the required output capacity for the refrigeration system 100 is determined. The required output capacity of the refrigeration system 100 is related to the cooling requirements imposed on the evaporator 108. The cooling requirement may be a function of the temperature of the liquid to be cooled, a function of the number of active evaporators, a combination of two or any other suitable factor. For example, in the refrigeration system 100 shown in FIG. 1, the cooling request is based on five of the evaporators 108, and at this time, the other three evaporators are in an inoperative state. This occurs in situations that can be seen in buildings. In such a situation, each evaporator 108 is provided to cool a specific area of the building.

  After determining the output capability of the refrigeration system 100 at step 402, the control system determines the configuration of the compressors 102 and 104 that satisfy this required output capability, or most efficiently, at step 404. The control system evaluates stored information such as the information of FIG. 2 about the compressor feature and determines the appropriate compressor feature. Information about the compressor configuration can be stored in any suitable way for the control system to retrieve it quickly and easily. Information can be stored in a table, database, or any other suitable form. In one embodiment, the control system can correlate the number of active evaporators 108 with a corresponding stage having a configuration that generates a suitable output capability. Referring back to the above example where five evaporators 108 are operating, the control system can select the fifth stage. This is consistent with the number of active evaporators 108 and has a compressor configuration that produces adequate output capacity. In another embodiment, the control system can compare the required output capability with each of the specific features and corresponding capabilities to determine which feature and capability best fits the required output capability. For example, if the requested output capability corresponds to 50% of the total capability, the control system compares the output capability for each feature and determines the closest feature to provide the required output capability of 50%.

  Finally, at step 404, the control system takes the determined compressor configuration and generates appropriate control signals for the compressors 102 and 104. The compressors 102 and 104 are then operated in the desired configuration to obtain the desired output capability in response to the control signal generated by the control system.

  Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that various changes can be made and the elements can be interchanged with equivalents without departing from the scope of the invention. Like. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the spirit of the invention. Accordingly, the invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but includes all embodiments within the scope of the appended claims.

It is the schematic of one Example of the refrigeration system of this invention. 2 is a table showing the corresponding configuration of two two-capacity compressors produced by the output capability stage and the control system of the present invention. Fig. 4 is a table showing the output capability provided by several different compressor configurations. It is a flowchart of the control process of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Refrigeration system 102 1st compressor 104 2nd compressor 106 Condenser 108 Evaporator 110 Expansion apparatus 140 Control panel

Claims (16)

In the refrigeration system,
A plurality of compressors having a plurality of predetermined actuating features, each predetermined actuating feature of the plurality of predetermined actuating features providing a predetermined output capability to the refrigeration system;
A condenser in fluid communication with the plurality of compressors;
Selecting from the at least one evaporator in fluid communication with the condenser and the plurality of compressors, and the plurality of predetermined operating configurations, a predetermined operating configuration that most efficiently satisfies the required output capability for the refrigeration system; A control system configured to control the plurality of compressors according to a required output capacity of the refrigeration system,
Each compressor of the plurality of compressors has a plurality of separate output capacities, and each of the predetermined operating configurations of the plurality of compressors includes an operating state and each operating compressor for each compressor of the plurality of compressors. Refrigeration system, including a separate output capability.   The refrigeration system of claim 1, wherein the at least one evaporator includes a plurality of evaporators, the total number of the plurality of evaporators being equal to the total number of the plurality of predetermined actuated features.   3. The refrigeration system according to claim 2, wherein the control system includes a memory that stores the plurality of predetermined operation states, and the plurality of predetermined operation states are sequentially identified in the memory in order of increasing output capability. Refrigeration system.   4. The refrigeration system of claim 3, wherein a preselected number of evaporators of the plurality of evaporators are operated by a control system in response to the selected predetermined operating configuration of the plurality of compressors, The refrigeration system, wherein the number of preselected evaporators corresponds to an order identifier for the selected predetermined working configuration of the plurality of compressors.   The refrigeration system according to claim 1, wherein each compressor of the plurality of compressors includes a two-capacity compressor having a first distinct output capability and a second distinct output capability.   6. The refrigeration system according to claim 5, wherein the plurality of compressors includes a first compressor and a second compressor.   The refrigeration system according to claim 6, wherein the plurality of predetermined operating states include eight operating states.   8. The refrigeration system of claim 7, wherein the eight operating states are configured to provide eight separate output capability stages for the refrigeration system.   The refrigeration system according to claim 6, wherein the first compressor and the second compressor are reciprocating compressors.   6. The refrigeration system of claim 5, wherein the second discrete output capability is greater than the first discrete output capability, and the second discrete output capability for the first compressor is the first discrete output capability. A refrigeration system greater than the second separate output capability for two compressors. In a method for controlling the operation of a plurality of multi-capacity compressors in a refrigeration system,
Providing a refrigeration system having a plurality of multi-capacity compressors, condensers, and a plurality of evaporators connected in a closed refrigeration circuit;
Determining the amount of output capacity required by the refrigeration system;
Determining a configuration of the plurality of multi-capacity compressors having a predetermined output capability to satisfy a determined amount of required output capability, wherein each multi-capacity compressor of the plurality of multi-capacity compressors includes a plurality of The determined configuration of the plurality of multi-capacity compressors having a separate output capability includes an operating state for each multi-capacity compressor of the plurality of multi-capacity compressors, and each of the multi-capacity compressors operating. Includes separate output capabilities,
Generating a control command corresponding to the determined configuration of the plurality of multi-capacity compressors, controlling the plurality of multi-capacity compressors and generating the predetermined output capability for the refrigeration system. .   12. The method of claim 11, wherein determining the plurality of multi-capacity compressor configurations includes selecting the plurality of multi-capacity compressor configurations from a plurality of configurations of the plurality of multi-capacity compressors. Wherein each feature of the plurality of features corresponds to a predetermined output capability of the refrigeration system.   13. The method of claim 12, further comprising storing the plurality of features of the plurality of multi-capacity compressors in a table.   14. The method of claim 13, wherein the step of selecting the plurality of multi-capacity compressor features includes selecting the plurality of multi-capacity compressor features from a table.   13. The method of claim 12, wherein the plurality of evaporators includes an evaporator for each form of the plurality of multi-capacity compressors of the plurality of forms of the plurality of multi-capacity compressors.   16. The method of claim 15, wherein the step of selecting the plurality of multi-capacity compressor configurations includes the step of selecting the plurality of multi-capacity compressors corresponding to the number of operating evaporators of the plurality of evaporators. Selecting a feature.

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