Refrigeration system, method of controlling the same and multi-stage refrigeration system

Abstract

The application discloses a refrigeration system, a control method thereof and a multi-stage refrigeration system. The refrigeration system comprises a main refrigeration circuit, a first bypass branch, an input end of which is connected to a discharge port of a compressor, a second bypass branch, an input end of which is connected to an output end of a condenser, an output end of the first bypass branch and an output end of the second bypass branch are connected to an input end of a second throttling device, an output end of the second throttling device is connected to a return port of the compressor, and a controller. The controller is used for controlling the conduction or shutdown of the first bypass branch, the conduction, shutdown or switching ratio of the second bypass branch and / or the switching ratio of the main refrigeration circuit according to a heating power parameter of a heating device in the refrigeration system, first temperature parameters of input and output ends of an evaporator and second temperature parameters in a box comprising the refrigeration system. Thus, the energy consumption of the whole refrigeration system is saved when the temperature of the box comprising the refrigeration system reaches a set temperature.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and in particular to a refrigeration system and its control method, as well as a multi-stage refrigeration system. Background Technology

[0002] With social development and technological advancements, refrigeration systems are being used in various industries. When the temperature of the refrigeration system's enclosure deviates slightly from the set temperature, it indicates that the enclosure has reached the set temperature. If the refrigeration system continues to operate in the previous state, it will increase the output power of the heating device, thus increasing the overall energy consumption of the refrigeration system. Summary of the Invention

[0003] This invention provides a refrigeration system and its control method, as well as a multi-stage refrigeration system, to solve the problem in related technologies where, when the temperature of the refrigeration system's enclosure has reached the set temperature, if the refrigeration system continues to operate in the previous state, it will increase the output power of the heating device and increase the energy consumption of the entire refrigeration system.

[0004] To address the aforementioned problems, a first aspect of the present invention provides a refrigeration system, comprising: a main refrigeration circuit formed by sequentially connecting a compressor, a condenser, a first throttling device, and an evaporator; further comprising: a first bypass branch, the input end of which is connected to the exhaust port of the compressor; a second bypass branch, the input end of which is connected to the output port of the condenser; the output ends of the first bypass branch and the second bypass branch merging and connecting to the input end of the second throttling device, the output end of which is connected to the return port of the compressor; and a controller, the controller being configured to control the conduction or cutoff of the first bypass branch, and control the conduction, cutoff, or switching ratio of the second bypass branch, and / or control the switching ratio of the main refrigeration circuit, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system.

[0005] According to one embodiment of the present invention, the first bypass branch includes a solenoid valve, the second bypass branch includes a first quick-opening valve, and the main refrigeration circuit includes a second quick-opening valve; the controller is connected to the solenoid valve, the first quick-opening valve, and the second quick-opening valve respectively, and is used to control the opening or closing of the solenoid valve according to the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including the housing of the refrigeration system, and to control the opening, closing, or switching ratio of the first quick-opening valve, and / or to control the switching ratio of the second quick-opening valve.

[0006] According to one embodiment of the present invention, the second bypass branch further includes a liquid storage tank, the inlet end of which is connected to the outlet end of the quick-opening valve, and the outlet end of which is connected to the input end of the second throttling device.

[0007] According to one embodiment of the present invention, both the first throttling device and the second throttling device include one of an electronic expansion valve, a capillary tube, and a thermostatic expansion valve.

[0008] To address the aforementioned problems, a second aspect of the present invention provides a multi-stage refrigeration system, including the refrigeration system described above.

[0009] To address the aforementioned problems, a third aspect of this invention proposes a control method for a refrigeration system, implemented based on the refrigeration system described above. The control method includes the following steps:

[0010] The heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator, and the second temperature parameters including the housing of the refrigeration system are obtained.

[0011] The first bypass branch is controlled to be turned on or off based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, and the on / off ratio of the second bypass branch is controlled, and / or the on / off ratio of the main refrigeration circuit is controlled.

[0012] According to one embodiment of the present invention, the heating power parameter includes: the actual heating power output of the heating device, and the duration when the actual heating power output is greater than the preset heating power output;

[0013] The first temperature parameters of the input and output terminals of the evaporator include: the temperature at the input terminal of the evaporator and the temperature at the output terminal of the evaporator;

[0014] The second temperature parameter in the enclosure of the refrigeration system includes: the set temperature of the enclosure and the measured temperature of the enclosure.

[0015] According to one embodiment of the present invention, the step of controlling the conduction or cutoff of the first bypass branch and controlling the conduction, cutoff, or switching ratio of the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, includes:

[0016] When the actual heating power output is greater than or equal to the first preset heating power output, and the duration of the actual heating power output being greater than or equal to the first preset heating power output is greater than or equal to the preset duration, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the housing and the measured temperature of the housing is less than or equal to the second preset temperature difference, and the set temperature of the housing is less than or equal to the preset temperature, the first bypass branch and the second bypass branch are simultaneously turned on, and / or the switching ratio of the main refrigeration circuit is controlled.

[0017] According to one embodiment of the present invention, the step of controlling the conduction or cutoff of the first bypass branch and controlling the conduction, cutoff, or switching ratio of the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, includes:

[0018] When the duration of the actual heating power output being less than the second preset heating power output, or the duration of the actual heating power output being greater than the first preset heating power output being less than the preset duration, or the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator being greater than the first preset temperature difference, or the absolute value of the difference between the set temperature of the housing and the measured temperature of the housing being greater than the second preset temperature difference, or the set temperature of the housing being greater than the preset temperature, the first bypass branch and the second bypass branch are controlled to be turned off simultaneously, and / or the on / off ratio of the main refrigeration circuit is controlled.

[0019] According to one embodiment of the present invention, after controlling the simultaneous conduction of the first bypass branch and the second bypass branch and / or the switching ratio of the main refrigeration circuit, the method further includes:

[0020] When the actual heating power output is greater than the second preset heating power output, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the chamber and the measured temperature of the chamber is less than or equal to the second preset temperature difference, and the set temperature of the chamber is less than or equal to the preset temperature, if the first bypass branch and the second bypass branch are simultaneously turned on, the on / off ratio of the second bypass branch is adjusted.

[0021] If the switching ratio of the main refrigeration circuit is controlled, then the switching ratio of the main refrigeration circuit will continue to be adjusted;

[0022] If the first bypass branch and the second bypass branch are simultaneously turned on and control the switching ratio of the main refrigeration circuit, then the switching ratio of the second bypass branch and / or the switching ratio of the main refrigeration circuit are adjusted.

[0023] In summary, the refrigeration system and its control method, and the multi-stage refrigeration system proposed in this invention include: a main refrigeration circuit formed by sequentially connecting a compressor, a condenser, a first throttling device, and an evaporator; it also includes: a first bypass branch, the input end of which is connected to the compressor's exhaust port; a second bypass branch, the input end of which is connected to the condenser's output port; the output ends of the first and second bypass branches merge and connect to the input end of the second throttling device, the output end of which is connected to the compressor's return port; and a controller, which controls the on / off state of the first bypass branch and the on / off state of the second bypass branch, and / or the on / off ratio of the second bypass branch, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters at the input and output ends of the evaporator, and the second temperature parameters in the housing of the refrigeration system, and / or the on / off ratio of the main refrigeration circuit, according to the heating power parameters of the heating device in the refrigeration system, the first temperature parameters at the input and output ends of the evaporator, and the second temperature parameters in the housing of the refrigeration system. Thus, energy consumption of the entire refrigeration system is saved when the temperature of the housing including the refrigeration system reaches the set temperature.

[0024] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a refrigeration system proposed according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a refrigeration system according to another embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of a multi-stage refrigeration system proposed according to an embodiment of the present invention;

[0029] Figure 4 This is a flowchart of the control method for the refrigeration system proposed in an embodiment of the present invention;

[0030] Figure 5This is a flowchart of a control method for a refrigeration system according to an embodiment of the present invention;

[0031] Figure 6 This is a flowchart of a control method for a refrigeration system proposed in another embodiment of the present invention;

[0032] Figure 7 This is a flowchart of a control method for a refrigeration system proposed in another embodiment of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] Figure 1 This is a schematic diagram of the structure of a refrigeration system according to an embodiment of the present invention. Figure 1 and 2 As shown, the refrigeration system 100 includes: a main refrigeration circuit formed by sequentially connecting a compressor 101, a condenser 102, a first throttling device 104, and an evaporator 105; it also includes:

[0036] The first bypass branch 113 has its input end connected to the exhaust port of the compressor 101.

[0037] The second bypass branch 114 has its input end connected to the output end of the condenser 102.

[0038] The output end of the first bypass branch 113 and the output end of the second bypass branch 114 merge and are connected to the input end of the second throttling device 112. The output end of the second throttling device 112 is connected to the return port of the compressor 101.

[0039] The controller 110 is used to control the conduction or cutoff of the first bypass branch 113 and the conduction, cutoff or switching ratio of the second bypass branch 114, and / or control the switching ratio of the main refrigeration circuit, based on the heating power parameters of the heating device 106 in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator 105, and the second temperature parameters including the housing of the refrigeration system.

[0040] It should be noted that the high-temperature, high-pressure gas discharged from the compressor 101 exhaust port forms a medium-temperature, high-pressure liquid in the condenser 102, then forms a low-temperature, low-pressure gas-liquid two-phase system in the first throttling device 104, and finally returns to the compressor 101 as a low-temperature, low-pressure gas in the evaporator 105. The refrigeration system 100 uses this main refrigeration circuit for cooling. For the first bypass branch 113 and the second bypass branch 116, the high-temperature, high-pressure gas discharged from the compressor 101 exhaust port and the medium-temperature, high-pressure liquid output from the condenser 102 are mixed and then returned to the compressor 101 return port through the second throttling device 112.

[0041] It is understood that during the refrigeration process, the first bypass branch 113 can be turned on or off, and the second bypass branch 114 can be turned on, off, or switched on / off, and / or the switching ratio of the main refrigeration circuit can be controlled, based on the heating power parameters of the heating device 106 in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator 105, and the second temperature parameters including those in the housing of the refrigeration system.

[0042] In other words, the stability of the refrigeration system can be determined based on the heating power parameters of the heating device 106 in the refrigeration system, the first temperature parameters at the input and output ends of the evaporator 105, and the second temperature parameters within the refrigeration system enclosure. The specific determination method is explained below. When the refrigeration system is in a stable state, the refrigerant flow required by the evaporator 105 decreases, allowing adjustment only of the on / off ratio of the main refrigeration circuit; or, adjusting only the simultaneous conduction of the first bypass branch 113 and the second bypass branch 114, and adjusting the on / off ratio of the second bypass branch 114 when it is conducting; or, simultaneously adjusting the on / off ratio of the main refrigeration circuit, and simultaneously conducting the first bypass branch 113 and the second bypass branch 114, and adjusting the on / off ratio of the second bypass branch 114 when it is conducting.

[0043] Specifically, by adjusting only the on / off ratio of the main refrigeration circuit, when the refrigeration system is in a steady state, the proportion of the main refrigeration circuit being on can be reduced, and the proportion being off can be increased. When the refrigeration system does not meet this steady state, the adjustment can be reversed, for example, reducing the proportion of off and increasing the proportion of on, with the sum of the on and off proportions being 100%. The on-off proportion can be understood as the opening degree of the main refrigeration circuit. Both increases and decreases are based on the opening degree of the main refrigeration circuit when the refrigeration system is in a steady state. This reduces the refrigerant flow entering the evaporator 105, thereby reducing the output of the heating device 106 and achieving energy saving.

[0044] By simultaneously activating the first bypass branch 113 and the second bypass branch 114, and adjusting the on / off ratio of the second bypass branch 114 while it is active, the percentage of the second bypass branch 114's on state can be gradually increased while its on / off ratio decreases when the refrigeration system is in a stable state. When the refrigeration system is not in a stable state, both the first bypass branch 113 and the second bypass branch 114 can be simultaneously deactivated. Both increases and decreases are based on the initial opening degree of the second bypass branch 114 when the refrigeration system is in a stable state; the initial opening degree can be set according to actual conditions. This reduces the refrigerant flow into the evaporator 105, thereby reducing the output of the heating device 106 and achieving energy savings.

[0045] The on / off ratio of the main refrigeration circuit, the first bypass branch 113, and the second bypass branch 114 can also be adjusted. For example, when the refrigeration system is in a stable state, the on / off ratio of the main refrigeration circuit can be reduced and the off / off ratio can be increased. The first bypass branch 113 and the second bypass branch 114 can be controlled to be turned on simultaneously, and the on / off ratio of the second bypass branch 114 can be gradually increased and the off / off ratio can be decreased. When the refrigeration system does not meet the stable state, the first bypass branch 113 and the second bypass branch 114 can be turned off simultaneously, and / or the opening degree of the main refrigeration circuit can be adjusted in the reverse direction. For example, the first bypass branch 113 and the second bypass branch 114 can be simultaneously shut off or the opening percentage of the second bypass branch 114 can be reduced to decrease the refrigerant diversion in the main refrigeration circuit. Alternatively, the opening percentage of the main refrigeration circuit can be directly increased. Or, the first bypass branch 113 and the second bypass branch 114 can be simultaneously shut off or the opening percentage of the second bypass branch 114 can be reduced, and the opening percentage of the main refrigeration circuit can be increased to increase the refrigerant flow into the evaporator 105, so as to keep the refrigeration system in a stable state as much as possible.

[0046] It should be explained that when the on / off ratio of the main refrigeration circuit, as well as the first bypass branch 113 and the second bypass branch 114, are adjusted simultaneously, a decrease in the on-state ratio and an increase in the off-state ratio in the main refrigeration circuit will lead to an increase in pressure within the main refrigeration circuit. Therefore, partially relieving pressure can be achieved by opening the first bypass branch 113 and the second bypass branch 114. Furthermore, the on / off ratio of the second bypass branch 114 can be adjusted to further divert refrigerant flow in the main refrigeration circuit. This not only protects the entire refrigeration system from overpressure but also achieves energy savings. When the on-state ratio in the main refrigeration circuit increases and the off-state ratio decreases, and the on-state ratio of the second bypass branch is reduced, or the first bypass branch 113 and the second bypass branch 114 are simultaneously closed, the refrigerant flow in the main refrigeration circuit can be quickly replenished, rapidly restoring the system to a stable state.

[0047] More specifically, the first bypass branch 113 includes a solenoid valve 115, the second bypass branch 114 includes a first quick-opening valve 116, and the main refrigeration circuit includes a second quick-opening valve 103; the controller 110 is connected to the solenoid valve 115, the first quick-opening valve 116, and the second quick-opening valve 103 respectively, and is used to control the solenoid valve 115 to open or close according to the heating power parameters of the heating device 106 in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator 105, and the second temperature parameters including the cabinet of the refrigeration system, and to control the opening, closing, or switching ratio of the first quick-opening valve 116, and / or control the switching ratio of the second quick-opening valve 103.

[0048] It is understood that the controller 110 can adjust the refrigerant flow into the evaporator 105 by turning the solenoid valve 115 on and off, or by adjusting the opening ratio of the first quick-opening valve 116 and the second quick-opening valve 103. Alternatively, if the opening of the main refrigeration circuit is not adjusted, a solenoid valve 103 can be installed on the main refrigeration circuit (e.g., Figure 1 (As shown). To adjust the opening degree of the main refrigeration circuit, a second quick-opening valve 103 can be installed on the main refrigeration circuit (e.g., Figure 2 (As shown).

[0049] Optionally, such as Figure 1 and Figure 2 As shown, the second bypass branch 114 also includes a liquid storage tank 117, the inlet end of which is connected to the outlet end of the quick-opening valve 116, and the outlet end of which is connected to the input end of the second throttling device 112.

[0050] Optionally, both the first throttling device 104 and the second throttling device 112 include one of an electronic expansion valve, a capillary tube, and a thermal expansion valve.

[0051] It should be noted that when the first throttling device 104 is an electronic expansion valve or a thermostatic expansion valve, a solenoid valve or a second quick-opening valve may not be installed in the main refrigeration circuit.

[0052] In this system, the high-temperature, high-pressure gas from the first bypass branch 113 mixes with the medium-temperature, high-pressure liquid from the second bypass branch 114. The medium-temperature, high-pressure liquid in the second bypass branch 114 cools the high-temperature, high-pressure gas before returning to the return port of the compressor 101 via the second throttling device 112 to protect the compressor. The liquid storage tank 116 can store the liquid refrigerant from the second bypass branch 114.

[0053] A humidification device 107 is also provided in the evaporator 105.

[0054] Figure 3 This is a schematic diagram of the structure of the multi-stage refrigeration system proposed in an embodiment of the present invention. Figure 3 As shown, the multi-stage refrigeration system 200 includes the refrigeration system as described above.

[0055] In this multi-stage refrigeration system 200, the high-temperature stage refrigeration system includes a first main refrigeration circuit and a second main refrigeration circuit; the low-temperature stage refrigeration system includes a low-temperature main refrigeration circuit. The first bypass branch and the second bypass branch can be located in the high-temperature stage refrigeration system, the low-temperature stage refrigeration system, or both. This invention does not specifically limit this. Furthermore, the multi-stage refrigeration system 200 exemplified in this example is a cascade refrigeration system. Multi-stage refrigeration systems can also include three-stage refrigeration systems, four-stage refrigeration systems, etc. The first bypass branch and the second bypass branch can be located in one or more of the stages, and corresponding quick-opening valves and / or solenoid valves can be installed in the corresponding main refrigeration circuits.

[0056] The following section will mainly introduce how to determine if the refrigeration system is in a stable state.

[0057] Figure 4 This is a flowchart of a control method for a refrigeration system proposed in an embodiment of the present invention. This method is implemented based on the refrigeration system described above, such as... Figure 4 As shown, the control method includes the following steps:

[0058] S101, acquire the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters of the housing of the refrigeration system;

[0059] S102, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including the housing of the refrigeration system, controls the conduction or shutdown of the first bypass branch, controls the conduction, shutdown, or switching ratio of the second bypass branch, and / or controls the switching ratio of the main refrigeration circuit.

[0060] Optionally, the aforementioned heating power parameters include: the actual heating power output of the heating device, and the duration when the actual heating power output exceeds the preset heating power output; wherein, the actual power output of the heating device can be calculated from the current and voltage values ​​of the heating device. The duration can be obtained using a timer.

[0061] The first temperature parameters of the evaporator's input and output terminals include: the temperature of the evaporator's input terminal and the temperature of the evaporator's output terminal; wherein, the temperature of the evaporator's input terminal and the temperature of the evaporator's output terminal can be obtained by temperature sensors installed at the evaporator's input and output terminals.

[0062] The second temperature parameter within the enclosure, including the refrigeration system, includes the set temperature of the enclosure and the measured temperature of the enclosure. The set temperature can be obtained through the controller itself, while the measured temperature can be obtained through a temperature sensor within the enclosure.

[0063] Specifically, S102 controls the on / off state of the first bypass branch and the on / off state of the second bypass branch based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including those in the casing of the refrigeration system, and / or controls the on / off state or switching ratio of the second bypass branch, and / or controls the switching ratio of the main refrigeration circuit, including:

[0064] When the actual heating power output is greater than or equal to the first preset heating power output, and the duration of the actual heating power output being greater than or equal to the first preset heating power output is greater than or equal to the preset duration, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the cabinet and the measured temperature of the cabinet is less than or equal to the second preset temperature difference, and the set temperature of the cabinet is less than or equal to the preset temperature, the first bypass branch and the second bypass branch are simultaneously turned on, and / or the switching ratio of the main refrigeration circuit is controlled.

[0065] In other words, when the actual heating power output is greater than or equal to the first preset heating power output, and the duration of this duration is greater than or equal to the preset duration, it indicates that the heating device of the refrigeration system has exceeded the first preset heating power output, and the measured temperature in the cabinet is expected to be close to the set temperature, meaning the refrigeration system is stabilizing. When the difference between the output temperature and the input temperature of the evaporator is less than or equal to the first preset temperature difference, it indicates that the superheat of the evaporator is within a certain range, also representing that the refrigeration system is stabilizing. When the absolute value of the difference between the set temperature and the measured temperature of the cabinet is less than or equal to the second preset temperature difference, it almost certainly confirms that the refrigeration system is in a stable state. In addition, when the set temperature of the cabinet is less than or equal to the preset temperature, it indicates that the entire refrigeration system is operating within the normal range. Therefore, when the aforementioned conditions are met, it can be determined that the refrigeration system is in a stable state, and then actions such as controlling the simultaneous conduction of the first bypass branch and the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit can be performed. The specific control logic can be found in the description in the refrigeration system embodiment, and will not be repeated here.

[0066] According to one embodiment of the present invention, S102 controls the conduction or cutoff of the first bypass branch and controls the conduction, cutoff, or switching ratio of the second bypass branch based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator, and the second temperature parameters including the housing of the refrigeration system, and / or controls the switching ratio of the main refrigeration circuit, including:

[0067] When the actual heating power output is less than the second preset heating power output, or the duration when the actual heating power output is greater than the first preset heating power output is less than the preset duration, or the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is greater than the first preset temperature difference, or the absolute value of the difference between the set temperature of the cabinet and the measured temperature of the cabinet is greater than the second preset temperature difference, or the set temperature of the cabinet is greater than the preset temperature, the first bypass branch and the second bypass branch are simultaneously shut off, and / or the switching ratio of the main refrigeration circuit is controlled.

[0068] In other words, if any one of the conditions is not met, it indicates that the refrigeration system cannot stabilize at a certain temperature. In this case, the first and second bypass branches are simultaneously shut off, and / or the switching ratio of the main refrigeration circuit is controlled. To prevent frequent simultaneous shut-off of the first and second bypass branches and / or control of the main refrigeration circuit's switching ratio, the refrigeration system can be considered unable to stabilize at a certain temperature only when the actual heating power output is less than a second preset heating power output. The first preset heating power output can be the maximum heating power output of the heating device, and the second preset heating power output can be the minimum heating power output of the heating device; these two values ​​can be set according to actual conditions.

[0069] Optionally, after controlling the simultaneous conduction of the first bypass branch and the second bypass branch and / or the switching ratio of the main refrigeration circuit, the method further includes:

[0070] When the actual heating power output is greater than the second preset heating power output, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the chamber and the measured temperature of the chamber is less than or equal to the second preset temperature difference, and the set temperature of the chamber is less than or equal to the preset temperature, if the first bypass branch and the second bypass branch are simultaneously turned on, the on / off ratio of the second bypass branch is adjusted.

[0071] If the switching ratio of the main refrigeration circuit is controlled, then the switching ratio of the main refrigeration circuit should be adjusted continuously.

[0072] If the first bypass branch and the second bypass branch are simultaneously turned on and control the switching ratio of the main refrigeration circuit, then the switching ratio of the second bypass branch and / or the switching ratio of the main refrigeration circuit are adjusted.

[0073] In other words, if the refrigeration system is still in a stable state after the first bypass branch and the second bypass branch are simultaneously turned on, the opening ratio of the second bypass branch can be increased and the closing ratio can be decreased.

[0074] After the switching ratio of the main refrigeration circuit is adjusted, the switching ratio of the main refrigeration circuit can be further adjusted while the refrigeration system is still in a stable state.

[0075] When the first bypass branch and the second bypass branch are simultaneously activated, and the switching ratio of the main refrigeration circuit is adjusted, the switching ratio of the second bypass branch, the switching ratio of the main refrigeration circuit, or both can be adjusted simultaneously. This results in lower energy consumption of the refrigeration system.

[0076] More specifically, the aforementioned parameters can be represented by the following symbols.

[0077] TPV, Current / Measured Temperature of the Cabinet, provided by a temperature sensor, unit: °C; TSV, Set / Target Temperature of the Cabinet, unit: °C; TSV_low, Initial Low Temperature Control Entry Value for Set Temperature (i.e., the set minimum target temperature), unit: °C; T_low_diff, Initial Low Temperature Control Entry Deviation Value for Set Temperature, unit: °C; T_constant_diff, Allowable Temperature Constant Fluctuation Value (i.e., the difference between the measured temperature and the target temperature), unit: °C; TQ_heater_output, Actual Power Output of the Heating System (i.e., Actual Heating Power Output), unit: %; TQ_heater_output_diff_max, Actual Power Output Control Value of the Heating System. The following parameters are defined: Input value (i.e., the first preset heating power output), unit: %; TQ_heater_output_diff_min, the input value for controlling the actual power output of the heating system (i.e., the second preset heating power output), unit: %; t_heater_output_diff_max, the input time (duration) for controlling the actual power output of the heating system, unit: s; t_duration, the duration (preset duration) for controlling the actual power output of the heating system, unit: s; T_evap, the evaporator input temperature, measured by a temperature sensor, unit: ℃; T_evap_out, the evaporator output temperature, measured by a temperature sensor, unit: ℃; dT_heating_max, the preset value for the temperature deviation at the evaporator inlet and outlet, i.e., the maximum allowable value, unit: ℃.

[0078] When the refrigeration system has started normally,

[0079] ①TSV≤TSV_low+T_low_diff;

[0080] ②|TSV-TPV|≤T_constant_diff;

[0081] ③TQ_heater_output≥TQ_heater_output_diff_max andT_evap_out-T_evap≤dT_heating_max;

[0082] ④t_heater_output_diff_max≥t_duration;

[0083] Entry condition: When all the above conditions ①, ②, ③ and ④ are satisfied simultaneously, the first bypass branch and the second bypass branch can be controlled to open at the same time, and / or the switching ratio of the main refrigeration circuit can be adjusted, so as to control the flow rate passing through the evaporator, reduce the output of the heating system, and thereby achieve an energy-saving effect.

[0084] Exit condition: When any one of the above conditions ①, ②, ③ and ④ is not satisfied, wherein when condition ③ is not satisfied but TQ_heater_output<TQ_heater_output_diff_min is satisfied, the control of turning off the first bypass branch and the second bypass branch, and / or adjusting the switching ratio of the main refrigeration circuit is performed.

[0085] In a specific embodiment, for example, as Figures 5 to 7 shown, the control method comprises:

[0086] S201: Acquire a target temperature;

[0087] S202: Determine whether the target temperature falls within a preset set temperature range. If yes, execute step S203; if no, return to step S201;

[0088] S203: Acquire the actually measured temperature of the box body in real time, and a first deviation value between the actually measured temperature and the target temperature;

[0089] S204: Determine whether the first deviation value is less than or equal to a second preset temperature difference value. If yes, execute step S205; if no, return to step S203;

[0090] S205: Acquire the actual heating power output of the heating device in real time;

[0091] S206: Determine whether the actual heating power output is greater than or equal to a first preset heating power output. If yes, execute step S207; if no, return to step S205;

[0092] S207: Acquire a second temperature deviation value between the temperature at the input end of the evaporator and the temperature at the output end of the evaporator;

[0093] S208: Determine whether the second deviation value is less than or equal to a first preset temperature difference value. If yes, execute step S209; if no, return to step S207;

[0094] S209: Acquire the duration during which the actual heating power output of the heating device is greater than or equal to the first preset heating power output;

[0095] S210: Determine whether the duration is greater than or equal to a preset duration. If yes, execute step S211; if no, return to step S209;

[0096] S211, control the first bypass branch and the second bypass branch to be simultaneously turned on; or adjust the switching ratio in the main refrigeration circuit; or control the first bypass branch and the second bypass branch to be simultaneously turned on and adjust the switching ratio in the main refrigeration circuit; return to step S205;

[0097] S212, determine whether the actual heating power output is less than the second preset heating power output; if yes, proceed to step S213; if no, proceed to step S214.

[0098] S213, correspondingly, control the first bypass branch and the second bypass branch to shut down simultaneously, or adjust the switching ratio in the main command circuit, or control the first bypass branch and the second bypass branch to shut down simultaneously and / or adjust the switching ratio in the main refrigeration circuit.

[0099] S214, correspondingly, adjust the switching ratio of the second bypass branch, or adjust the switching ratio in the main refrigeration circuit, or simultaneously adjust the switching ratio of the second bypass branch and / or the switching ratio in the main refrigeration circuit.

[0100] In summary, the refrigeration system and its control method, and the multi-stage refrigeration system proposed in this invention include: a main refrigeration circuit formed by sequentially connecting a compressor, a condenser, a first throttling device, and an evaporator; it also includes: a first bypass branch, the input end of which is connected to the compressor's exhaust port; a second bypass branch, the input end of which is connected to the condenser's output port; the output ends of the first and second bypass branches merge and connect to the input end of the second throttling device, the output end of which is connected to the compressor's return port; and a controller, which controls the on / off state of the first bypass branch and the on / off state of the second bypass branch, and / or the on / off ratio of the second bypass branch, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters at the input and output ends of the evaporator, and the second temperature parameters in the housing of the refrigeration system, and / or the on / off ratio of the main refrigeration circuit, according to the heating power parameters of the heating device in the refrigeration system, the first temperature parameters at the input and output ends of the evaporator, and the second temperature parameters in the housing of the refrigeration system. Thus, energy consumption of the entire refrigeration system is saved when the temperature of the housing including the refrigeration system reaches the set temperature.

[0101] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0102] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A refrigeration system (100), characterized in that, include: The main refrigeration circuit is formed by sequentially connecting the compressor (101), condenser (102), first throttling device (104), and evaporator (105); it also includes: The first bypass branch (113) has its input end connected to the exhaust port of the compressor (101); The second bypass branch (114) has its input end connected to the output end of the condenser (102); The output end of the first bypass branch (113) and the output end of the second bypass branch (114) are connected to the input end of the second throttling device (112), and the output end of the second throttling device (112) is connected to the return port of the compressor (101); The controller (110) is used to control the on or off of the first bypass branch (113) and the on / off of the second bypass branch (114) according to the heating power parameters of the heating device (106) in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator (105), and the second temperature parameters including the housing of the refrigeration system, and / or control the on / off ratio of the main refrigeration circuit; The heating power parameters include: the actual heating power output of the heating device, and the duration when the actual heating power output is greater than the preset heating power output; The first temperature parameters of the input and output terminals of the evaporator include: the temperature at the input terminal of the evaporator and the temperature at the output terminal of the evaporator; The second temperature parameter in the enclosure of the refrigeration system includes: the set temperature of the enclosure and the measured temperature of the enclosure; The method of controlling the on / off state of the first bypass branch and controlling the on / off or switching ratio of the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, includes: When the actual heating power output is greater than or equal to the preset heating power output, and the duration of the actual heating power output being greater than or equal to the first preset heating power output is greater than or equal to the preset duration, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the housing and the measured temperature of the housing is less than or equal to the second preset temperature difference, and the set temperature of the housing is less than or equal to the preset temperature, the first bypass branch and the second bypass branch are simultaneously turned on, and / or the switching ratio of the main refrigeration circuit is controlled.

2. The refrigeration system according to claim 1, characterized in that, The first bypass branch (113) includes a solenoid valve (115), the second bypass branch (114) includes a first quick-opening valve (116), and the main refrigeration circuit includes a second quick-opening valve (103). The controller (110) is connected to the solenoid valve (115), the first quick-opening valve (116), and the second quick-opening valve (103) respectively, and is used to control the solenoid valve (115) to open or close according to the heating power parameters of the heating device (106) in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator (105), and the second temperature parameters including the housing of the refrigeration system, and to control the opening, closing, or switching ratio of the first quick-opening valve (116), and / or control the switching ratio of the second quick-opening valve (103).

3. The refrigeration system according to claim 2, characterized in that, The second bypass branch (114) also includes a liquid storage tank (117), the inlet end of which is connected to the outlet end of the quick-opening valve (116), and the outlet end of which is connected to the input end of the second throttling device (112).

4. The refrigeration system according to claim 1, characterized in that, Both the first throttling device (104) and the second throttling device (112) include one of an electronic expansion valve, a capillary tube, and a thermal expansion valve.

5. A multi-stage refrigeration system, characterized in that, Includes the refrigeration system as described in any one of claims 1-4.

6. A control method for a refrigeration system, characterized in that, Based on the refrigeration system as described in any one of claims 1-4, the control method includes the following steps: The heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output terminals of the evaporator, and the second temperature parameters including the housing of the refrigeration system are obtained. The system controls the on / off state of the first bypass branch and the on / off state of the second bypass branch based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, and / or controls the on / off state of the main refrigeration circuit.

7. The control method for the refrigeration system according to claim 6, characterized in that, The heating power parameters include: the actual heating power output of the heating device, and the duration when the actual heating power output is greater than the preset heating power output; The first temperature parameters of the input and output terminals of the evaporator include: the temperature at the input terminal of the evaporator and the temperature at the output terminal of the evaporator; The second temperature parameter in the enclosure of the refrigeration system includes: the set temperature of the enclosure and the measured temperature of the enclosure.

8. The control method for the refrigeration system according to claim 7, characterized in that, The method of controlling the on / off state of the first bypass branch and controlling the on / off or switching ratio of the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, includes: When the actual heating power output is greater than or equal to the preset heating power output, and the duration of the actual heating power output being greater than or equal to the first preset heating power output is greater than or equal to the preset duration, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the housing and the measured temperature of the housing is less than or equal to the second preset temperature difference, and the set temperature of the housing is less than or equal to the preset temperature, the first bypass branch and the second bypass branch are simultaneously turned on, and / or the switching ratio of the main refrigeration circuit is controlled.

9. The control method for the refrigeration system according to claim 7, characterized in that, The method of controlling the on / off state of the first bypass branch and controlling the on / off or switching ratio of the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit, based on the heating power parameters of the heating device in the refrigeration system, the first temperature parameters of the input and output ends of the evaporator, and the second temperature parameters including those in the housing of the refrigeration system, includes: When the duration of the actual heating power output being less than the second preset heating power output, or the duration of the actual heating power output being greater than the first preset heating power output being less than the preset duration, or the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator being greater than the first preset temperature difference, or the absolute value of the difference between the set temperature of the housing and the measured temperature of the housing being greater than the second preset temperature difference, or the set temperature of the housing being greater than the preset temperature, the first bypass branch and the second bypass branch are controlled to be turned off simultaneously, and / or the on / off ratio of the main refrigeration circuit is controlled.

10. The control method for the refrigeration system according to claim 8, characterized in that, The method of simultaneously activating the first bypass branch and the second bypass branch, and / or controlling the switching ratio of the main refrigeration circuit, further includes: When the actual heating power output is greater than the second preset heating power output, and the difference between the temperature at the output end of the evaporator and the temperature at the input end of the evaporator is less than or equal to the first preset temperature difference, and the absolute value of the difference between the set temperature of the chamber and the measured temperature of the chamber is less than or equal to the second preset temperature difference, and the set temperature of the chamber is less than or equal to the preset temperature; If the first bypass branch and the second bypass branch are both conducting simultaneously, then the conduction switching ratio of the second bypass branch is adjusted. If the switching ratio of the main refrigeration circuit is controlled, then the switching ratio of the main refrigeration circuit will continue to be adjusted; If the first bypass branch and the second bypass branch are simultaneously turned on and control the switching ratio of the main refrigeration circuit, then the switching ratio of the second bypass branch and / or the switching ratio of the main refrigeration circuit are adjusted.

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