JP2012172890A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerating apparatus in which a refrigeration capability and an energy saving performance of the entire refrigerating apparatus are improved by making a heat exchange capability proper in an air-cooled condenser of a high-temperature side cycle and an air-cooled intermediate cooler of a low-temperature side cycle.SOLUTION: A refrigerating apparatus includes a high-temperature side cycle device 10 which forms a high-temperature side circulation circuit, a low-temperature side cycle device 20 which has an air-cooled intermediate cooler and forms a low-temperature side circulation circuit, a cascade condenser 30 which is comprised of a high-temperature side evaporator 14 and a low-temperature side condenser 22 and performs heat exchange between a high-temperature side refrigerant and a low-temperature side refrigerant, an air blower 40 for blowing air into a high-temperature side air-cooled condenser 12 and the air-cooled intermediate cooler 25, and a control device 60 which determines a final output of the air blower 40 on the basis of a first air blower output result determined based on a physical quantity related to the high-temperature side circulation circuit and a second air blower output result determined based on a physical quantity related to the low-temperature side circulation circuit.

Description

  The present invention relates to a multi-source refrigeration apparatus in which a plurality of refrigeration cycle apparatuses (refrigerant circulation circuits) are configured in multiple stages. In particular, the present invention relates to the control of a blower for sending air for heat exchange with a refrigerant in a heat exchanger.

  Conventionally, for example, a refrigeration cycle apparatus (hereinafter referred to as a high temperature side cycle) on the high temperature side (high stage side, primary side) and a refrigeration cycle apparatus (hereinafter referred to as a low temperature side cycle) on the low temperature side (low stage side, secondary side). And a refrigeration apparatus configured in multiple stages (here, it is assumed that it is a two-stage dual refrigeration apparatus). In a multi-stage refrigeration system, the air-cooled condenser of the high-temperature side cycle and the air-cooled intermediate cooler of the low-temperature side cycle share a blower that flows through the low-temperature cycle and the high-temperature cycle. There are some which cool a refrigerant (for example, refer to patent documents 1).

  In such a refrigeration system, the capacity of the compressor in the high-temperature side cycle is usually based on the temperature on the refrigerant outlet side of the air-cooled intermediate cooler (described in Patent Document 1 as a pre-stage radiator) that the low-temperature side cycle has. The pressure on the high pressure side (high pressure) in the low temperature side cycle is kept constant.

Japanese Patent Laying-Open No. 2008-2759 (FIG. 1)

  In the conventional multi-component refrigeration system, as described above, the air-cooled condenser and the low-temperature side cycle of the high-temperature side cycle are based on the temperature on the refrigerant outlet side of the air-cooled intermediate cooler (previous radiator) of the low-temperature side cycle. The air blower that cools the air-cooled intercooler at the same time was controlled. For this reason, the heat exchange capacity (heat radiation capacity) of the air-cooled condenser in the high-temperature side cycle may not be properly achieved, causing problems such as insufficient cooling capacity and poor energy efficiency (operation efficiency).

  The present invention solves such a problem. The heat exchange capacity of the air-cooled condenser of the high-temperature side cycle and the air-cooled intermediate cooler of the low-temperature side cycle is made appropriate, and the refrigeration capacity and energy saving of the entire refrigeration apparatus are achieved. A refrigeration apparatus with further improved performance is obtained.

  The refrigeration apparatus according to the present invention is configured to connect a high temperature side compressor, a high temperature side air-cooled condenser, a high temperature side expansion device, and a high temperature side evaporator to form a high temperature side circulation circuit for circulating a high temperature side refrigerant. The low-temperature side forms a low-temperature side circulation circuit that circulates the low-temperature side refrigerant by connecting the cycle device to the low-temperature side compressor, air-cooled intercooler, low-temperature side condenser, low-temperature side expansion device, and low-temperature side evaporator. A cascade device that includes a cycle device, a high-temperature side evaporator, and a low-temperature side condenser, and performs heat exchange between the high-temperature side refrigerant and the low-temperature side refrigerant, and is arranged in a direction substantially perpendicular to the direction in which air flows. A blower for sending air to the high temperature side air-cooled condenser and the air-cooled intermediate cooler, the result of the first blower output determination based on the heat exchange in the high-temperature side air-cooled condenser, and the air-cooled intermediate cooler Second based on heat exchange in Based on the results of the blower output determination, in which a control device for determining an output of the blower.

  The refrigeration apparatus of the present invention has a first blower output result determined based on heat exchange of the high temperature side condenser in the high temperature side circulation circuit and a second blower output result determined based on heat exchange of the low temperature side intercooler. Based on the above, the final blower output is determined and controlled so that the heat exchange capacity (heat radiation capacity) of the high-temperature side air-cooled condenser or the low-temperature side air-cooled intercooler may be insufficient. Therefore, it is possible to sufficiently dissipate heat, and the energy-saving performance can be improved without impairing the cooling ability to the cooling target (load) by the low-temperature evaporator.

It is a figure showing the structure of the freezing apparatus in embodiment of this invention. 4 is a diagram illustrating an input / output relationship in control centering on a control device 60. FIG. It is a figure showing the Mollier diagram in the refrigeration apparatus of embodiment. It is a figure (the 1) which shows the theoretical calculation value of system efficiency (COP). It is a figure (the 2) which shows the theoretical calculation value of system efficiency (COP). It is a figure showing the optimal relationship between the low pressure of the low temperature side cycle 20, and a high pressure. It is a figure of the flowchart of the air blower 40 control based on the high temperature side cycle. It is a figure showing the relationship between outside temperature and target condensation temperature. It is a figure of the flowchart of air blower 40 control based on the low temperature side cycle. It is a figure for showing the output determination procedure to the final air blower. It is a figure showing the theoretical calculation value of required heat exchange amount.

Embodiment.
FIG. 1 is a diagram showing a configuration of a refrigeration apparatus in an embodiment of the present invention. As shown in FIG. 1, in the present embodiment, a multi-component refrigeration apparatus (a binary refrigeration apparatus in FIG. 1) that has a high-temperature side cycle 10 and a low-temperature side cycle 20 and constitutes a refrigerant circulation circuit that circulates the refrigerant. Will be described.

  In the binary refrigeration apparatus of the present embodiment, a cascade condenser (inter-refrigerant heat exchanger) configured by combining the high-temperature side evaporator 14 and the low-temperature side condenser 22 so as to enable heat exchange between the refrigerants passing therethrough, respectively. ) 30 is provided, and the two refrigerant circulation circuits have a multistage configuration. And it has the air blower 40 which supplies the air for heat exchange to the high temperature side condenser 12 and the low temperature side intercooler (auxiliary condenser) 25. Moreover, it has the control apparatus 60 which performs operation control of the whole binary refrigeration apparatus. Here, the levels of temperature and pressure described below are not particularly determined in relation to absolute values, but are based on relationships that are relatively determined in the state, operation, etc. of the device. It shall be written.

  In FIG. 1, a high temperature side cycle 10 includes a high temperature side compressor 11, a high temperature side condenser 12, a high temperature side expansion device 13, and a high temperature side evaporator 14 connected in series by a refrigerant pipe, and a high temperature side refrigerant. A circulation circuit (hereinafter, referred to as a high temperature side circulation circuit) is configured. On the other hand, in the low temperature side cycle 20, a low temperature side compressor 21, a low temperature side intercooler 25, a low temperature side condenser 22, a low temperature side expansion device 23, and a low temperature side evaporator 24 are connected in series with a refrigerant pipe. Thus, a low-temperature side refrigerant circulation circuit (hereinafter referred to as a low-temperature side circulation circuit) is configured.

In the binary refrigeration apparatus having such a configuration, for example, R410A, R32, R404A, HFO-1234yf, propane, isobutane, carbon dioxide (CO ₂ ) are used as the refrigerant circulating in the high-temperature side circulation circuit (hereinafter referred to as high-temperature side refrigerant). Ammonia or the like is used. Further, carbon dioxide (CO ₂ ), nitrogen, air, or the like is used as a refrigerant circulating through the low temperature side circulation circuit (hereinafter referred to as a low temperature side refrigerant). Here, a case where R410A, which is an HFC refrigerant, is used as the high-temperature side refrigerant, and carbon dioxide (CO ₂ ) is used as the low-temperature side refrigerant.

  Each component apparatus of a binary refrigeration apparatus is demonstrated in detail. The high temperature side compressor 11 of the high temperature side cycle 10 sucks the high temperature side refrigerant, compresses it, and discharges it in a high temperature / high pressure state. Here, in this Embodiment, the high temperature side compressor 11 shall be comprised with the compressor of the type which can adjust the discharge amount of a high temperature side refrigerant | coolant by rotation speed control, such as an inverter circuit, for example. Then, the low pressure pressure value (high temperature side low pressure value) in the high temperature side cycle 10 and the high pressure pressure and temperature detector 52 provided in the low temperature side cycle 20 related to detection by the low pressure side pressure / temperature detector 51 provided in the high temperature side cycle 10. Based on the high-pressure value (low-temperature-side high-pressure value) in the low-temperature cycle 20 related to this detection, the controller 60 performs driving so that the amount of heat exchange between the refrigerants in the cascade capacitor 30 is not insufficient.

  The high temperature side condenser 12 is an air-cooled condenser that performs heat exchange between the air supplied from the blower 40 and the high temperature side refrigerant and condenses and liquefies the high temperature side refrigerant. The high temperature side expansion device 13 such as a pressure reducing valve or an expansion valve expands the high temperature side refrigerant by reducing the pressure. For example, it is optimally configured by a flow rate control device such as an electronic expansion valve, but may be configured by a refrigerant flow rate adjusting means such as a capillary tube or a temperature-sensitive expansion valve. The high temperature side evaporator 14 evaporates the high temperature side refrigerant by heat exchange. For example, here, it is assumed that the heat transfer tube or the like through which the high-temperature side refrigerant passes in the cascade capacitor 30 serves as the high-temperature side evaporator 14 and performs heat exchange with the low-temperature side refrigerant.

  On the other hand, the low temperature side compressor 21 of the low temperature side cycle 20 sucks the low temperature side refrigerant, compresses the refrigerant, and discharges it in a high temperature / high pressure state. The low temperature side compressor 21 is also composed of a compressor of a type that has, for example, an inverter circuit and can adjust the discharge amount of the low temperature side refrigerant. And based on the low pressure value (low temperature side low pressure value) in the low temperature side cycle 20 concerning the detection of the low pressure pressure and temperature detector 53 provided in the low temperature side cycle 20, the controller 60 controls the low temperature side evaporator 24. Driving is performed so that the supplied cooling capacity is not insufficient.

  The low temperature side intercooler 25 functions as a gas cooler or a condenser, performs heat exchange between the air supplied from the blower 40 and the low temperature side refrigerant, and assists in condensing and liquefying the low temperature side refrigerant in the low temperature side condenser 22. This is an air-cooled heat exchanger. Here, in the present embodiment, the blower 40 that sends air for heat exchange to the low temperature side intercooler 25 is common to the high temperature side condenser 12. And the low temperature side intercooler 25 and the high temperature side condenser 12 shall be arrange | positioned along with the direction where the air of the air blower 40 flows substantially perpendicularly. The low temperature side condenser 22 condenses and liquefies the low temperature side refrigerant by heat exchange. For example, here, it is assumed that the heat transfer tube or the like through which the low-temperature side refrigerant passes in the cascade condenser 30 serves as the low-temperature side condenser 22 and performs heat exchange with the high-temperature side refrigerant.

  The low temperature side expansion device 23 such as a pressure reducing valve or an expansion valve decompresses the low temperature side refrigerant to expand it. For example, it is optimal to configure with flow rate control means such as an electronic expansion valve, but it may be configured with refrigerant flow rate control means such as capillaries. Here, it is assumed that the low temperature side throttle device 23 is constituted by a flow rate control means for adjusting the opening degree based on an instruction from the control device 60.

  The low temperature side evaporator 24 performs heat exchange between air, brine, and the like supplied from, for example, a blower, a pump, or the like (not shown) and the low temperature side refrigerant to evaporate the low temperature side refrigerant. The object to be cooled or the like is directly or indirectly cooled by heat exchange with the low-temperature side refrigerant. Here, the blower or the like that supplies air or the like to the low-temperature side evaporator 24 is different from the blower 40 that supplies air or the like to the high-temperature side condenser 12 or the low-temperature side intercooler 25.

  The blower 40 supplies air for heat exchange to both the high temperature side condenser 12 and the low temperature side intercooler 25. The blower 40 can adjust the output (the amount of air to be supplied, the amount of air flow), for example, when the control device 60 controls the rotation speed of a propeller or the like. At this time, the control device 60 sets the high pressure value (high temperature side high pressure value) in the high temperature side cycle 10 related to the detection of the high pressure pressure / temperature detector 50 provided in the high temperature side cycle 10, the high pressure pressure / temperature detector 52. Based on the low temperature side high pressure value related to detection and the temperature values related to detection by the intermediate cooler outlet temperature detector 54 and the outside air temperature detector 55, the heat exchange capabilities of the high temperature side condenser 12 and the low temperature side intermediate cooler 25 are The blower 40 is driven to adjust the output so as not to run out. The adjustment of the output is performed by increasing (increasing), decreasing (decreasing), or rotating the number of revolutions of the propeller or the like by a predetermined amount each time it is determined.

  The high pressure / temperature detector 50 is provided between the refrigerant discharge side of the high temperature side compressor 11 and the high temperature side expansion device 13 in the high temperature side circulation circuit (high temperature side cycle 10). It is a detector for detecting. The low pressure / temperature detector 51 is provided between the high temperature side expansion device 13 and the refrigerant suction side of the high temperature compressor 11 in the high temperature side circulation circuit (high temperature side cycle 10). It is a detector for detecting. The high pressure / temperature detector 52 is provided between the refrigerant discharge side of the low temperature side compressor 21 and the low temperature side expansion device 23 in the low temperature side circulation circuit (low temperature side cycle 20). It is a detector for detecting. The low pressure and temperature detector 53 is provided between the low temperature side expansion device 23 and the refrigerant suction side of the low temperature side compressor 21 in the low temperature side circulation circuit (low temperature side cycle 20). It is a detector for detecting. The intermediate cooler outlet temperature detector 54 detects the temperature of the low temperature side refrigerant flowing out from the low temperature side intermediate cooler 25. The outside air temperature detector 55 detects the temperature of air (outside air) outside the space to be cooled. Here, it installs in the place which can detect the temperature of the air before heat-exchanging with the high temperature side condenser 12 and the low temperature side intercooler 25 as outside temperature.

  FIG. 2 is a diagram showing the input / output relationship in the control centering on the control device 60. The control device 60 performs arithmetic processing based on detected values such as pressure values and temperature values determined from signals related to detection of each pressure and temperature detector, and performs the high temperature side compressor 11, the low temperature side compressor 21, and the blower. Control the drive of an actuator such as 40. For example, it is determined whether the target value is higher or lower (larger or smaller) based on the value related to detection by the low pressure / temperature detector 51, and signals are sent to the high temperature side compressor 11 and the high temperature side expansion device 13. To control the drive. Further, based on the value related to detection by the low pressure / temperature detector 53, it is determined whether it is higher or lower than the target value, and a signal is sent to the low temperature side compressor 21 and the low temperature side expansion device 23 to control the drive. To do.

  And especially this Embodiment demonstrates drive control of the air blower 40 by the control apparatus 60. FIG. In controlling the driving of the blower 40, based on the values related to detection by the high pressure / temperature detector 50 and the outside air temperature detector 55, high pressure pressure saturation temperature conversion, target condensation temperature calculation, high temperature side cycle 10 (high temperature side refrigerant) Processing such as output determination of the blower 40 in the circulation circuit) is performed and stored in the storage unit 61. Further, based on the values relating to the detection of the high pressure / temperature detector 52, the intermediate cooler outlet temperature detector 54, and the outside air temperature detector 55, the high pressure pressure saturation temperature conversion, the low temperature side cycle 20 (low temperature side refrigerant circulation circuit) Processing such as output determination of the blower 40 is performed and stored in the storage unit 61. And based on each output determination result, a final output is determined, a signal is sent to the air blower 40, and a drive is controlled. More specific contents of the processing in the control device 60 will be described in detail later.

  FIG. 3 is a diagram illustrating a Mollier diagram in the refrigeration apparatus according to the embodiment of the present invention. Based on FIG. 3, the state of the refrigerant in each refrigerant circuit will be described. In the high-temperature side refrigerant cycle on the diagram, the state of the high-temperature side refrigerant when the high-temperature side compressor 11 sucks is at position A. And the state of the high temperature side refrigerant | coolant which went out of the high temperature side compressor 11 becomes a position of B, and the state after passing the high temperature side condenser 12 and heat-exchanging becomes a position of C. Thereafter, the state of the high-temperature side refrigerant that has passed through the high-temperature side expansion device 13 is at the position D, and when it passes through the cascade capacitor 30, it is at the position A. The high temperature side refrigerant repeats the state change (phase change) based on this cycle.

On the other hand, in the low-temperature side refrigerant cycle on the diagram, the state of the low-temperature side refrigerant when the low-temperature side compressor 21 sucks is at the position E. In addition, the state of the low-temperature side refrigerant that has left the low-temperature side compressor 21 is at the position F. The low temperature side refrigerant passes through the low temperature side intercooler 25 and is heat-exchanged. Here, as described above, the low temperature side refrigerant is carbon dioxide (CO ₂ ). Therefore, for example, when the outside air temperature is a temperature corresponding to the isothermal line T1 lower than the high pressure saturation temperature of the low temperature side cycle 20, the state of the low temperature side refrigerant exiting the low temperature side intercooler 25 is up to the position of G1. Can be heat exchanged. On the other hand, when the outside air temperature is a temperature corresponding to the isothermal line T2 higher than the high pressure saturation temperature, the low temperature side refrigerant that has exited the low temperature side intercooler 25 can exchange heat up to a state corresponding to the position of G2 (low temperature If the side intercooler 25 has sufficient heat exchange capability with the outside air, it can exchange heat up to the position H). This may also apply to the high temperature side cycle 10, but in this embodiment, R410A, which is an HFC refrigerant whose high pressure saturation temperature is always higher than the outside air temperature in a general environment, is used as the high temperature side refrigerant. Therefore, there is no particular problem.

  Thereafter, the state of the low-temperature side refrigerant that has passed through the cascade condenser 30 is at the position H, and when it passes through the low-temperature side expansion device 23, it is at the position J. And when it passes through the low temperature side evaporator 24, it will be in the position of E. The state of the low temperature side refrigerant repeats the state change (phase change) based on this cycle.

  Here, based on the value related to detection by the low pressure / temperature detector 51, the control device 60 can obtain the pressure value (high temperature side low pressure) and the temperature value of the high temperature side refrigerant at the position A. Further, based on the value related to the detection by the high pressure and temperature detector 52, the pressure of the high temperature side refrigerant (high temperature side high pressure) and the temperature value at the position C can be obtained. Based on these temperature value and pressure value, the enthalpy difference represented by the line AD can be calculated. The product of the difference in enthalpy and the circulation amount of the high-temperature side refrigerant calculated based on the drive frequency of the high-temperature side compressor 11 (A-D enthalpy difference × refrigerant circulation amount) is the high-temperature side evaporation in the cascade capacitor 30. It becomes the heat exchange capability used for the heat exchange between the refrigerant | coolants which pass through the condenser 14 and the low temperature side condenser 22, respectively.

  In order not to run out of this capability, the control device 60 has a value related to detection by the low pressure / temperature detector 51 higher (larger) than the target value with respect to the pressure or temperature value corresponding to the target line AD. If it is determined, a signal for increasing the output (operation frequency) of the high temperature side compressor 11 is transmitted. If it is determined that the value is lower (smaller) than the target value, a signal for decreasing the output is transmitted. Alternatively, when the control device 60 determines that the value related to detection by the low-pressure pressure / temperature detector 51 is higher than the target value, the control device 60 decreases the opening degree of the high-temperature side expansion device 13 and determines that the value is lower than the target value. May send a signal to increase the opening.

  Further, on the diagram, the target value of the low pressure of the high temperature side cycle 10 corresponding to the line AD is about 5 to 10 ° C. (K) in terms of saturation temperature with respect to the saturation temperature of the target high pressure of the low temperature side cycle 20. Set the value to a low temperature. This is because heat exchange in the cascade capacitor 30 cannot physically be performed unless there is a temperature difference of about 5 ° C. or more at least, and the operation efficiency of the entire apparatus deteriorates even if there is an excessive temperature difference.

  Further, the target value of the high pressure of the low temperature side cycle 20 is set to a value that is 5 to 32.5 ° C. higher than the saturation temperature of the target low pressure of the low temperature side cycle 20 in terms of the saturation temperature. Here, since the value set as the target value has an optimum value depending on the refrigerant to be used, it needs to be changed according to the low temperature side refrigerant to be used.

  The target value of the low pressure of the low temperature side cycle 20 is a value set by the installer according to the user's application. With respect to the set target value of the low pressure, the actual low temperature side low pressure value is a value related to detection by the low pressure / temperature detector 53. In order not to make the capacity required for the low-temperature side evaporator 24 short, the control device 60 sets the value related to detection by the low-pressure pressure / temperature detector 53 to the target pressure or temperature corresponding to the target line EJ. When it is determined that the value is higher than the value, a signal for increasing the output of the low temperature side compressor 21 is sent. When it is determined that the output is lower than the target value, a signal for decreasing the output is sent. Alternatively, when the control device 60 determines that the value related to detection by the low-pressure pressure / temperature detector 53 is higher than the target value, the control device 60 decreases the opening of the low-temperature side expansion device 23 and determines that the value is lower than the target value. May send a signal to increase the opening.

4 and 5 are diagrams showing theoretical calculation values of system efficiency (COP: Coefficient Of Performance) when the high temperature side refrigerant is R410A and the low temperature side refrigerant is carbon dioxide (CO ₂ ). 4 and 5, the high temperature pressure saturation temperature of the high temperature side cycle is 45 ° C., and the temperature difference in the cascade capacitor 30 (high pressure pressure saturation temperature on the low temperature side cycle 20 side−low pressure pressure saturation temperature on the high temperature side cycle 10 side) is 10K. The refrigerant displacement of the low temperature side compressor 21 is a fixed value. When the low-pressure pressure saturation temperature of the low-temperature cycle 20 shown in FIG. 4 is −10 ° C., the load capacity (system ability) is 27.6 kW, and when the low-pressure saturation temperature shown in FIG. 5 is −40 ° C. This is a calculated value when the high pressure saturation temperature of the low temperature side cycle 20 is changed with the load capacity set to 11.31 kW.

  FIG. 4A and FIG. 5A show a table listing the calculation results. FIGS. 4B and 5B show the relationship between the high pressure saturation temperature and the system efficiency (COP) of the low temperature side cycle 20 from FIG. System efficiency (COP) is the ratio of system capacity to system input (input to hot cycle 10 + input to cold cycle 20). As shown in FIGS. 4 and 5, if the system capacity is the same, the smaller the system input, the better the efficiency. As shown in FIG. 4B, when the low pressure of the low temperature side cycle 20 is a pressure that becomes −10 ° C. in terms of saturation temperature, the high pressure of the low temperature side cycle 20 is about 5 ° C. in terms of saturation temperature. The efficiency (COP) is best when the pressure is In addition, as shown in FIG. 5B, when the low pressure of the low temperature side cycle 20 is a pressure at which the low temperature side cycle is −40 ° C., the high temperature pressure of the low temperature side cycle is about −10 ° C. The efficiency (COP) is the best when the pressure becomes.

  FIG. 6 is a diagram illustrating the optimum relationship between the low pressure and the high pressure in the low temperature side cycle 20. FIG. 6 shows a saturated temperature conversion value for the high pressure of the low temperature side cycle 20 that is most efficient when the low pressure of the low temperature side cycle 20 is −45 to 10 ° C. in terms of saturation temperature. For the low temperature side cycle 20, the control device 60 may determine the target value so as to be the high pressure saturation temperature shown in FIG. 6 according to the target low pressure saturation temperature, and operate the refrigeration system. . Here, in consideration of the measurement accuracy of the high-pressure pressure and temperature detector 52, it is preferable to keep the target high-pressure pressure saturation temperature within ± 2.5 ° C.

  Next, drive control of the blower 40 will be described. As described above, in order to drive the blower 40, the control device 60 first increases the output of the blower 40 using individual information (data) separately in the high temperature side cycle 10 and the low temperature side cycle 20, Determine whether to keep down or keep current output. And based on the output determination result concerning the high temperature side cycle 10 and the low temperature side cycle 20, it is set as the flow which finally determines the output of the air blower 40. FIG.

  FIG. 7 is a flowchart illustrating a process for deriving the output determination result (first fan output result) of the blower 40 in the high temperature side cycle 10. First, in step S1, it is determined whether or not the value of the high pressure saturation temperature in the high temperature side cycle 10 is larger than a value obtained by adding 1 (° C.) to the target value. Here, 1 (° C.) is added to the target value in order to suppress hunting in the control and to provide a dead zone for ensuring stability. The high pressure saturation temperature is calculated by the control device 60 based on the value (high temperature side high pressure value) related to detection by the high pressure / temperature detector 50 described above. Further, the target value is a value calculated by the control device 60 based on the value of the outside air temperature that is detected by the outside air temperature detector 55, and a value that is higher by about 5 to 20 ° C. than the value of the outside air temperature is set as the target value. Here, the reason for providing the difference of 5 to 20 ° C. will be described. For example, when the outside air temperature is low, a pressure difference between the high pressure and the low pressure is ensured, and in order for the high temperature side refrigerant to flow from the high pressure side to the low pressure side, the minimum differential pressure that is about 20 ° C. in terms of saturation temperature difference conversion is Necessary. In addition, under conditions where the outside air is high enough to ensure the minimum differential pressure between the high pressure and the low pressure, the efficiency becomes better when the high pressure is as low as possible. For this reason, the target is 5 ° C. or more at which air (outside air) and the high-pressure refrigerant flowing in the high-temperature side condenser 12 can physically exchange heat.

  FIG. 8 is a diagram showing the relationship between the outside air temperature and the target (target condensation temperature) of the high pressure saturation temperature. Based on the above-described temperature difference, a target relationship between the outside air temperature and the high pressure saturation temperature as shown in FIG. 8 is provided. For example, when the outside air temperature is 5 ° C. or less, the target of the high pressure saturation temperature is about 25 ° C., and when the outside temperature is 40 ° C. or more, the target of the high pressure saturation temperature is about 45 ° C. When the outside air temperature is 5 to 40 ° C., a target value is obtained by proportionally approximating a value between 25 ° C. and 45 ° C. which is the target high pressure saturation temperature when the outside air temperature is 5 ° C. and 40 ° C. . Here, FIG. 8 differs depending on the high temperature side refrigerant to be used, and there is an optimum value for each refrigerant. Therefore, it is necessary to change according to the refrigerant to be used.

  If it is determined in step S1 that the high pressure saturation temperature is greater than the value obtained by adding 1 (° C.) to the target temperature, the process proceeds to step S2 and it is determined that the output of the blower 40 is increased.

  If it is determined in step S1 that the value of the high pressure saturation temperature is equal to or less than the target value plus 1 (° C.), the process proceeds to step S3. In step S3, it is determined whether or not the value of the high pressure saturation temperature is smaller than a value obtained by subtracting 1 (° C.) from the target value. The reason for subtracting 1 (° C.) from the target value is to provide a dead zone in order to ensure stability as described above.

  In step S3, when it is determined that the value of the high pressure saturation temperature is smaller than the value obtained by subtracting 1 (° C.) from the target value, the process proceeds to step S4, and it is determined that the output of the blower 40 is reduced. If it is determined that the value of the high pressure saturation temperature is equal to or greater than the value obtained by subtracting 1 (° C.) from the target value, the process proceeds to step S5, and it is determined that the current output of the blower 40 is maintained.

  FIG. 9 is a view showing a flowchart of processing for deriving the output determination result (second blower output result) of the blower 40 in the low temperature side cycle 20. First, in step S11, it is determined whether or not the value of the high pressure saturation temperature in the low temperature side cycle 20 is larger than the value of the outside air temperature. As described above, in the low temperature side cycle 20, as shown in FIG. 3 and the like, the amount of heat that can be exchanged is different depending on whether or not the outside air temperature is higher than the high pressure saturation temperature, and the reference temperature for calculating the degree of cooling is different. Because. The high pressure saturation temperature is a value calculated by the control device 60 based on the value (low temperature side high pressure value) related to the detection by the high pressure and temperature detector 52 as described above, and the value of the outside air temperature is the outside air temperature detection. The value detected by the device 55.

  If it is determined that the value of the high pressure saturation temperature is greater than the value of the outside air temperature, the process proceeds to step S12. In step S12, it is determined whether or not a value obtained by subtracting the value of the high-pressure pressure saturation temperature from the value of the intermediate cooler outlet temperature is smaller than 5 (K). The reason for providing the difference of 5K is a margin for reliably performing drive control based on detection accuracy variations and detection errors of the high pressure / temperature detector 52 and the outside air temperature detector 55. The intermediate cooler outlet temperature value is a value detected by the intermediate cooler outlet temperature detector 54.

  If it is determined in step S12 that the value is smaller than 5 (K), it is determined that the cooling is sufficiently performed, and the process proceeds to step S13, where it is determined that the output of the blower 40 is reduced. If it is determined in step S12 that the value obtained by subtracting the value of the high-pressure pressure saturation temperature from the value of the intermediate cooler outlet temperature is not smaller than 5 (K) (5 or more), the process proceeds to step S14.

  In step S14, it is determined whether or not a value obtained by subtracting the value of the high-pressure pressure saturation temperature from the value of the intermediate cooler outlet temperature is greater than 10 (K). In addition to the above 5K, the meaning of 10K is to suppress the hunting of the control and to provide 10K by further providing a 5K dead zone in order to ensure stability.

  If it is determined in step S14 that it is greater than 10 (K), it is determined that the cooling is insufficient, and the process proceeds to step S15, where it is determined that the output of the blower 40 is increased. When it is determined in step S14 that the value obtained by subtracting the value of the high-pressure pressure saturation temperature from the value of the intermediate cooler outlet temperature is not greater than 10 (K) (10 or less), the process proceeds to step S16 and the blower 40 is turned on. It is determined that the current output is maintained.

  If it is determined in step S11 that the value of the high pressure saturation temperature is not greater than the value of the outside air temperature, the process proceeds to step S17. In step S17, it is determined whether or not a value obtained by subtracting the value of the outside air temperature from the value of the intermediate cooler outlet temperature is smaller than 5 (K). When it is determined that it is smaller than 5 (K), the process proceeds to step S18, and it is determined that the output of the blower 40 is to be reduced. If it is determined in step S17 that the value obtained by subtracting the outside air temperature value from the intermediate cooler outlet temperature value is not smaller than 5 (K) (5 (K) or more), the process proceeds to step S19.

  In step S19, it is determined whether or not the value obtained by subtracting the value of the outside air temperature from the value of the intermediate cooler outlet temperature is greater than 10 (K). When it is determined that it is greater than 10 (K), the process proceeds to step S20, and it is determined that the output of the blower 40 is increased. If it is determined in step S19 that the value obtained by subtracting the value of the outside air temperature from the value of the intermediate cooler outlet temperature is not greater than 10 (K) (10 or less), the process proceeds to step S21 and the current output of the blower 40 is obtained. Is determined to be maintained. Here, in this embodiment, the values for 5K and 10K are set as margins, etc., but these values are optimum depending on the refrigerant used, so it is desirable to change according to the refrigerant used. .

  FIG. 10 is a diagram for illustrating a procedure for determining the final output to the blower 40. In the output determination process of the blower 40 related to the high temperature side cycle 10 and the low temperature side cycle 20 described above, one of up, current maintenance, and down was determined. As shown in FIG. 10, since nine combinations (1) to (9) are generated depending on the combination of the determination results, how to finally determine the output of the blower 40 for each combination Represents.

  Here, the intention of the determination is to satisfy both the necessary heat exchange amount in the high-temperature side condenser 12 and the necessary heat exchange amount in the low-temperature side intercooler 25 so that the capacity as a refrigeration apparatus is not deficient. (If either of the necessary heat exchange amounts is not satisfied, the capacity of the refrigeration apparatus may be insufficient and will not be excessive). Moreover, in order to avoid the failure by the abnormal operation accompanying the high pressure increase in the high temperature side cycle 10 or the low temperature side cycle 20 due to the output reduction of the blower 40, the priority order of reducing the output of the blower 40 is lowered. Yes (match the one that needs the output of the large blower 40).

  For example, in either (1), (2), (3), (4) and (7), either the high temperature side cycle 10 or the low temperature side cycle 20 determines that the output of the blower 40 is increased. Final decision is made. In addition, both the high temperature side cycle 10 and the low temperature side cycle 20 determine whether the output of the blower 40 is maintained (5), and either the high temperature side cycle 10 or the low temperature side cycle 20 determines that the output of the blower 40 is down. In (6) and (8), it is determined that the current output of the blower 40 is maintained.

The above-described control for avoiding an abnormal increase in the high pressure is particularly effective when using a refrigerant such as carbon dioxide (CO ₂ ) whose critical temperature may be lower than the outside air temperature. Carbon dioxide (CO ₂ ) has a critical temperature of about 31 ° C. According to the Japan Meteorological Agency website, the highest outdoor temperature in Japan is 40.9 ° C. Here, the installation status of the refrigeration apparatus may generally be about 20 ° C. higher than the outside temperature announced by the Japan Meteorological Agency. Therefore, in consideration of this, when using a refrigerant whose critical temperature is 61 ° C. or less, is used. It can be said that it is effective.

FIG. 11 is a diagram illustrating theoretical calculation values of necessary heat exchange amounts in the high-temperature side condenser 12, the cascade condenser 30, and the low-temperature side intercooler 25. In FIG. 11, the low temperature side refrigerant is carbon dioxide (CO ₂ ), and the high temperature side refrigerant is R410A. The calculation conditions are as follows: in the low temperature side cycle 20, the condensation temperature is 5 ° C, the evaporation temperature is -10 ° C, the subcool (supercooling degree) is 5K, the intake gas temperature of the low temperature side compressor 21 is 18 ° C, and the required cooling capacity is 27.06 kW. . In the high temperature side cycle 10, the condensation temperature is 45 ° C., the evaporation temperature is −5 ° C., the subcool 5K, and the intake gas temperature of the high temperature side compressor 11 is 18 ° C.

  From FIG. 11, when the heat exchange amount in the high temperature side condenser 12 of the high temperature side cycle 10 is 100% (heat exchange ratio), the low temperature side condenser 22 and the low temperature side intercooler 25 of the low temperature side cycle 20 are combined. The amount of heat exchange is about 80.7%. Among them, the necessary heat exchange amount in the low temperature side intercooler 25 is required to be about 17.1%. Therefore, the low-temperature side intercooler 25 may be configured by a heat exchanger having a heat exchange capacity of 17% or more with respect to the heat exchange capacity of the high-temperature side condenser 12. It can be said that it is optimal for controlling.

  Further, from FIG. 11, if the low temperature side intercooler 25 has a heat exchange capacity of about 80.7% or more with respect to the heat exchange capacity of the high temperature side condenser 12, the cascade condenser 30 (low temperature side condensation). It is also possible to exchange heat of the low-temperature side refrigerant only with air (outside air) without exchanging heat with the high-temperature side refrigerant in the vessel 22). For example, when the high-pressure saturation temperature of the low temperature side cycle 20 is lower than the outside air temperature, the output determination of the blower 40 in the high temperature side cycle 10 shown in FIG. Process. By making the output determination result a final decision and sending a signal based on the output determination result, the refrigeration apparatus can be operated more efficiently in terms of energy and the like.

  As described above, according to the refrigeration apparatus of the present embodiment, the control device 60 increases or decreases the air volume of the blower 40 based on the high pressure and the outside air temperature in the high temperature side cycle 10 (high temperature side circulation circuit) or Determining whether to maintain, and increasing the air volume of the blower 40 based on the high pressure in the low temperature side cycle 20 (low temperature side circulation circuit), the temperature on the refrigerant outflow side of the low temperature side intercooler 25 and the outside air temperature, Since the final output is determined based on the two determination results to drive the blower 40, the air volume of the blower 40 is determined based on both refrigeration cycle devices. be able to. At this time, as a result of increasing the output rather than maintaining and decreasing the output, the result of maintaining the output is prioritized over the decrease of the output, and finally determining which one needs the output of the large blower 40 is high. The air volume required for the side condenser 12 and the low temperature side intercooler 25 can be ensured at the same time, and the energy efficient operation or the like can be performed as the entire apparatus. And the heat exchange capability shortage in the high temperature side cycle 10 and the low temperature side cycle 20 can be prevented. Further, it is possible to prevent a failure due to an abnormal increase in the high-pressure pressure of the high-temperature cycle 10 or the low-temperature cycle 20 (excessiveness can be suppressed when the reverse determination is made).

  Moreover, in the low temperature side cycle 20 (low temperature side circulation circuit), the value based on the temperature range which the refrigeration apparatus cools can be set by setting the target value of the high pressure based on the low pressure. Furthermore, since the target value of the saturated temperature converted value of the high-pressure pressure in the high-temperature side circulation circuit is set to be 5 to 20 ° C. higher than the outside air temperature in the determination, the pressure between the high pressure and the low pressure is determined. The high temperature side refrigerant can be circulated while ensuring the difference. Based on this target, based on the difference between the temperature on the refrigerant outlet side of the low temperature side intercooler, the saturated temperature converted value of high pressure in the low temperature side cycle 20 (low temperature side circulation circuit), or the value of the outside air temperature. Thus, the pressure difference can be secured by setting the target range of the condensation temperature in the high temperature side condenser 12. And it is detected by comparing the value obtained by subtracting the saturated temperature converted value of the low temperature side high pressure or the value of the outside air temperature from the temperature value on the refrigerant outlet side of the low temperature side intercooler 25 with the range of 5 to 10K. It is possible to make a determination in consideration of an error or the like.

  Furthermore, since the low temperature side intercooler 25 has a heat exchange capacity of 17% or more with respect to the heat exchange capacity of the high temperature side condenser 12, the balance of the heat exchange capacity in each heat exchanger of the refrigeration apparatus. An optimal intercooler can be configured in the air volume distribution of the blower 40 with the high-temperature side condenser 12. In particular, if the heat exchange capacity is about 80.7% or more, depending on the environmental conditions such as the outside air temperature, heat exchange by air is not performed in the cascade condenser 30 (low temperature side condenser 22). Since it can be performed, it is not necessary to perform the operation of the high temperature side cycle 10, and the operation can be performed more efficiently.

  DESCRIPTION OF SYMBOLS 10 High temperature side cycle, 11 High temperature side compressor, 12 High temperature side condenser, 13 High temperature side throttle device, 14 High temperature side evaporator, 20 Low temperature side cycle, 21 Low temperature side compressor, 22 Low temperature side condenser, 23 Low temperature side throttle Equipment, 24 Low temperature side evaporator, 25 Low temperature side intercooler, 30 Cascade condenser, 40 Blower, 50 High pressure and temperature detector, 51 Low pressure and temperature detector, 52 High pressure and temperature detector, 53 Low pressure Temperature detector, 54 intercooler outlet temperature detector, 55 outside air temperature detector, 60 control device, 61 storage means.

Claims (7)

A high-temperature side cycle device that forms a high-temperature-side circulation circuit that circulates a high-temperature-side refrigerant by pipe-connecting a high-temperature side compressor, a high-temperature side air-cooled condenser, a high-temperature side expansion device, and a high-temperature side evaporator;
A low-temperature side cycle device that forms a low-temperature-side circulation circuit that circulates the low-temperature-side refrigerant by pipe-connecting a low-temperature side compressor, an air-cooled intermediate cooler, a low-temperature side condenser, a low-temperature side expansion device, and a low-temperature side evaporator;
A cascade capacitor configured by the high temperature side evaporator and the low temperature side condenser, and performing heat exchange between the high temperature side refrigerant and the low temperature side refrigerant,
A blower for sending air to the high-temperature side air-cooled condenser and the air-cooled intermediate cooler arranged in a direction substantially perpendicular to the direction in which the air flows;
Based on the result of the first blower output determination based on the heat exchange in the high-temperature side air-cooled condenser and the result of the second blower output determination based on the heat exchange in the air-cooled intermediate cooler, A refrigeration apparatus comprising: a control device that determines an output. The controller is
The first blower output determination based on the saturation temperature value of the high-pressure pressure in the high-temperature side circulation circuit and the value of the outside air temperature that is the temperature of the air fed into the high-temperature side air-cooled condenser and the air-cooled intermediate cooler And performing the second blower output determination based on the saturation temperature value of the high-pressure pressure in the low-temperature side circulation circuit, the temperature value of the refrigerant on the outflow side of the air-cooled intermediate cooler, and the value of the outside air temperature. The refrigeration apparatus according to claim 1, wherein The controller is
Setting a target value of the high pressure in the high temperature side circulation circuit based on the outside air temperature, which is the temperature of the air sent to the high temperature side air cooled condenser and the air cooled intermediate cooler,
The refrigeration apparatus according to claim 1 or 2, wherein a target value of the high pressure in the low temperature side circulation circuit is set based on the low pressure in the low temperature side circulation circuit. The controller is
The temperature value on the refrigerant outlet side of the air-cooled intermediate cooler and the saturation temperature value of the high pressure in the low-temperature side circulation circuit, or the temperature of the air fed into the high-temperature air-cooled condenser and the air-cooled intermediate cooler The refrigeration apparatus according to any one of claims 1 to 3, wherein a target range of a condensation temperature in the high temperature side air-cooled condenser is set based on a difference from a value of an outside air temperature. The controller is
Saturation temperature of high-pressure pressure in the high-temperature side circulation circuit so that the temperature is 5 to 20 ° C. higher than the outside air temperature which is the temperature of the air sent to the high-temperature side air-cooled condenser and the air-cooled intermediate cooler in terms of saturation temperature Set a target value of the value, determine the first blower output by comparing the target value with the saturation temperature value of the high pressure in the high temperature side circulation circuit,
A value obtained by subtracting the saturation temperature value of the low temperature side high pressure or the value of the outside air temperature from the temperature value on the refrigerant outlet side of the air-cooled intermediate cooler is compared with a range of 5 to 10 K, and the second blower output The refrigeration apparatus according to claim 1, wherein the refrigeration apparatus is determined. The controller is
When the result of the first blower output determination and the result of the second blower output determination are different, the result of increasing the output rather than maintaining and decreasing the output or the result of maintaining the output rather than decreasing the output 6. The refrigeration apparatus according to claim 1, wherein the output of the blower is determined with priority.   The air-cooled intermediate cooler has a heat exchange capacity of 17% or more with respect to the heat exchange capacity of the high-temperature side air-cooled condenser. Refrigeration equipment.

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