JP2010112651A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiple cooling system of high temperature controllability of a cooled object. <P>SOLUTION: In this multiple cooling system capable of cooling a plurality of cooled objects respectively to different temperatures, a refrigerant passing through a first evaporator 104 for cooling the first cooled object is introduced to a sucking section of a compressor 101, a refrigerant passing through a second evaporator 204 for cooling the second cooled object is guided to an intermediate connecting section 205, and a first cooled object temperature detecting section 51 for detecting a temperature of the first cooled object, and a second cooled object temperature detecting section 61 for detecting a temperature of the second cooled object are disposed. A first expansion valve control section 50 controls a temperature of the first cooled object by controlling a first expansion valve 103 for adjusting a flow of the refrigerant to the first evaporator 104, and a second expansion valve control section 60 controls a temperature of the first cooled object by controlling a second expansion valve 203 for adjusting a flow of the refrigerant to the second evaporator 204. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus that can cool a plurality of objects to be cooled to different temperatures.

  2. Description of the Related Art Conventionally, a refrigerating apparatus that constitutes a so-called multi-cooling system that includes a plurality of evaporators in one refrigerant circuit and can cool a plurality of objects to be cooled to different temperatures has been known (see, for example, Patent Document 1). The multi-cooling system simplifies the configuration of the refrigeration system by cooling multiple objects to be cooled with a single refrigerant circuit, reducing the number of components, improving reliability, and reducing costs. There is an advantage of becoming.

Note that the refrigeration apparatus of Patent Document 1 includes a plurality of brine circuits that circulate a secondary refrigerant (brine) and cool an object to be cooled separately from a refrigerant circuit in which a primary refrigerant is circulated and a refrigeration cycle is executed. The multi-cooling system is configured by cooling the object to be cooled by circulating the brines, which are connected to the plurality of evaporators and having different temperatures, in the plurality of brine circuits.
Japanese Patent No. 3660961

  FIG. 5 is a schematic diagram showing the refrigeration apparatus of Patent Document 1 constituting the multi-cooling system. In such a configuration of Patent Document 1, the second expansion valve 203 and the second evaporator 204 of the second evaporator refrigerant pipe 20 and the first expansion valve 103 and the first evaporator 104 of the refrigerant circuit 10 are condensed. Between the outlet of the compressor 102 and the suction part of the compressor 101 ′.

  Therefore, the flow distribution of the refrigerant discharged from the condenser 102 to the first evaporator 104 and the second evaporator 204 is determined by the opening ratio between the first expansion valve 103 and the second expansion valve 203. . Therefore, when the opening degree of the upstream expansion valve is changed in order to control the ability of one evaporator, the refrigerant flow rate of the other evaporator changes, so the ability of the other evaporator also changes. That is, the control of the first expansion valve 103 and the control of the second expansion valve 203 interfere with each other.

  As described above, in the refrigeration apparatus constituting the conventional multi-cooling system, the flow rates of the first expansion valve and the second expansion valve change with one change. Therefore, it is easy for hunting of the expansion valve to occur due to the flow rate change. As a result, there is a problem that the controllability of the temperature of the object to be cooled is lowered.

  The present invention has been made in view of such a conventional technical problem, and prevents hunting of the expansion valve by preventing interference between the control of the first expansion valve and the control of the second expansion valve. It aims at providing the freezing apparatus which comprises the multi-cooling system with high temperature controllability of a cooling material.

  The refrigeration apparatus according to claim 1 is a refrigerant in which a refrigerant circulates in a circuit in which a compressor, a condenser, a first expansion valve whose opening degree can be adjusted, and a first evaporator are connected by a refrigerant pipe. An intermediate connection that is branched from a branch portion provided in a refrigerant pipe between the circuit and the condenser and the first expansion valve in the refrigerant circuit and provided in the middle of the compression mechanism of the compressor A second evaporator refrigerant pipe which is a refrigerant pipe connected to a section, a second evaporator provided in the middle of the second evaporator refrigerant pipe, and the section between the branch section and the second evaporator A second expansion valve provided in the refrigerant pipe, the opening of which is adjustable, a first cooled object temperature detecting unit for detecting a temperature of the first cooled object cooled by the first evaporator, and the second evaporation. A second object-to-be-cooled temperature detector for detecting the temperature of the second object to be cooled that is cooled by the vessel; A first expansion valve control unit that controls the opening of the first expansion valve based on the temperature detected by the cooled object temperature detection unit so that the temperature of the first cooled object falls within a predetermined range; Second expansion valve control for controlling the opening of the second expansion valve based on the temperature detected by the second cooled object temperature detecting unit so that the temperature of the second cooled object falls within a predetermined range. A section.

  According to the refrigeration apparatus of the first aspect, the refrigerant that has passed through the first evaporator is guided to the suction portion of the compressor, and the refrigerant that has passed through the second evaporator is guided to the intermediate connection portion. It is burned. That is, the refrigerant that has passed through the second evaporator flows into the intermediate connection portion, bypassing the second evaporator refrigerant pipe. Therefore, the change in the refrigerant flow rate to the second evaporator due to the change in the opening of the second expansion valve is caused by the circulation amount of the refrigerant flowing through the first evaporator and flowing into the suction portion of the compressor. Has little effect. Therefore, as compared with the refrigeration apparatus constituting the conventional multi-cooling system, the occurrence of hunting of the expansion valve accompanying the flow rate change is suppressed, and the temperature controllability of the object to be cooled can be improved.

  The refrigeration apparatus according to claim 2 is the refrigeration apparatus according to claim 1, wherein the first evaporation that detects an evaporation temperature that is a temperature when the refrigerant in the refrigerant circuit is a saturated gas in the first evaporator. A temperature detection unit; a second evaporation temperature detection unit that detects an evaporation temperature that is a temperature when the refrigerant in the second evaporator refrigerant pipe is a saturated gas in the second evaporator; and an operating state of the compressor A compressor control unit that controls the temperature of the refrigerant passing through the first evaporator based on the temperature detected by the first evaporation temperature detection unit. The rotation speed of the compressor is controlled so as to fall within the range, and in addition to the control, the second expansion valve control unit further controls the second expansion valve control unit based on the temperature detected by the second evaporation temperature detection unit. 2 The evaporation temperature of the refrigerant passing through the evaporator is within a predetermined range. Sea urchin, sets an upper limit opening degree to a maximum opening degree of the second expansion valve.

  According to the refrigeration apparatus of the second aspect, the evaporating temperature of the refrigerant passing through the evaporator is controlled so as to be within a predetermined range. Accordingly, it is possible to prevent the cooling capacity from being hindered due to an increase in the evaporation temperature of the refrigerant in the evaporator. This is because when the opening degree of the expansion valve is increased, the flow rate of the refrigerant passing through the evaporator downstream of the expansion valve increases, and the pressure of the refrigerant in the evaporator rises. As the refrigerant evaporating temperature rises and the temperature difference between the evaporating temperature and the object to be cooled decreases, the increase in the opening of the expansion valve acts to counteract the improvement in cooling capacity due to the increase in the refrigerant flow rate. However, this action can be suppressed.

  The refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the second aspect, wherein the second expansion valve control unit is configured to perform the evaporation of the refrigerant passing through the temperature of the second cooled object and the second evaporator. When the temperature difference from the temperature is less than a predetermined value, the upper limit opening is set by reducing the opening of the second expansion valve.

  As described above, the increase in the opening degree of the second expansion valve acts in a direction to cancel the improvement in the cooling capacity due to the increase in the refrigerant flow rate. This action is achieved when the temperature difference between the temperature of the second object to be cooled and the evaporation temperature of the refrigerant passing through the second evaporator becomes less than a predetermined value, that is, the opening of the second expansion valve is Exceeding the upper limit corresponding to the temperature difference exceeds the improvement in cooling capacity due to an increase in the refrigerant flow rate. Further, since the refrigerant that has passed through the second evaporator is guided to the intermediate connection portion, the pressure of the refrigerant does not change due to increase or decrease in the rotation speed of the compressor. Therefore, the evaporation temperature of the refrigerant in the second evaporator cannot be controlled by controlling the rotation speed of the compressor. According to the refrigeration apparatus of the third aspect, when the temperature difference becomes less than a predetermined value, the upper limit opening is set by reducing the opening of the second expansion valve. The cooling capacity of the vessel can be maximized.

  A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to the second or third aspect, wherein the first evaporating temperature detecting unit is between the first evaporator and the suction unit of the compressor. A first pressure detection unit configured to detect a pressure of the refrigerant gas passing through the refrigerant pipe, and calculating an evaporation temperature based on the pressure, wherein the second evaporation temperature detection unit is connected to the second evaporator and the intermediate connection A second pressure detection unit that detects the pressure of the refrigerant gas passing through the refrigerant pipe between the first and second units, and calculates an evaporation temperature based on the pressure.

  According to the refrigeration apparatus according to claim 4, the saturation temperature corresponding to the pressure of the refrigerant gas detected by the first pressure detection unit and the second pressure detection unit is set as the evaporation temperature. It is possible to easily detect the evaporation temperature of the refrigerant that is difficult to perform.

  The refrigeration apparatus according to claim 5 is the refrigeration apparatus according to any one of claims 1 to 4, wherein the refrigeration apparatus is a brine circuit connected to the first evaporator, wherein the brine in the brine circuit and the brine circuit A first brine circuit in which the brine is cooled by heat exchange with the refrigerant in the refrigerant circuit in the first evaporator, and a brine circuit connected to the second evaporator, the brine circuit being in the brine circuit And a second brine circuit that cools the brine by heat exchange between the brine passing through the second evaporator refrigerant pipe and the second evaporator. The temperature detector detects the brine temperature at the outlet of the first evaporator of the first brine circuit, and the second cooled object temperature detector detects the outlet of the second evaporator of the second brine circuit. Part brine temperature is detected.

  According to the refrigeration apparatus of the fifth aspect, the object to be cooled is cooled not by the evaporator provided in the refrigerant circuit that executes the refrigeration cycle but by the brine circuit provided separately from the refrigerant circuit. Therefore, since the piping length of the refrigerant circuit can be suppressed, the apparatus can be miniaturized and the degree of freedom of the installation location of the refrigeration apparatus can be increased.

  According to the present invention, the first expansion, which is a disadvantage of the conventional multi-cooling system, is maintained while maintaining the advantages of the conventional multi-cooling system, in which the number of components is reduced, reliability is improved, and the cost can be reduced. Interference between the control of the valve and the control of the second expansion valve, and hunting of the expansion valve associated with the interference can be suppressed. Therefore, it is possible to provide a refrigeration apparatus constituting a multi-cooling system with high temperature controllability of an object to be cooled.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (Configuration of Refrigeration Apparatus) FIG. 1 is a schematic diagram showing a refrigeration apparatus 1 according to an embodiment of the present invention. The refrigerating apparatus 1 includes a refrigerant circuit 10, a second evaporator refrigerant pipe 20, a first brine circuit 30, a second brine circuit 40, a first expansion valve control unit 50, a second expansion valve control unit 60, and a compressor control unit 70. Is provided.

  The refrigerant circuit 10 is a circuit in which a refrigeration cycle is executed, and a compressor 101, a condenser 102, an adjustable first expansion valve 103, and a first evaporator 104 are connected by a refrigerant pipe. ing.

  The compressor 101 includes, for example, a scroll type compression mechanism. The compressor 101 compresses the low-temperature / low-pressure refrigerant vapor sent from the first evaporator 104 into a high-temperature / high-pressure refrigerant vapor. As in the case of the conventional refrigeration apparatus, the compressor 101 is discharged from the compressor 101 based on the detection value of a pressure sensor or a temperature sensor (not shown) provided in the discharge section of the compressor 101 in order to protect the compressor 101. The temperature control of the refrigerant gas is performed.

  The condenser 102 is, for example, a plate heat exchanger, and cools the high-temperature and high-pressure refrigerant discharged from the compressor 101 by exchanging heat between the refrigerant circulating in the refrigerant circuit 10 and, for example, cooling water. Let it be a high-pressure liquid refrigerant in a cooled state.

  The first expansion valve 103 is an electronic expansion valve that is driven by, for example, a stepping motor, and freely adjusts the opening degree by changing the number of pulses of the stepping motor. By the expansion of the first expansion valve 103, the high-pressure liquid refrigerant becomes a low-temperature / low-pressure refrigerant and is sent to the first evaporator 104.

  The first evaporator 104 is, for example, a plate heat exchanger, and exchanges heat between the brine circulating in the first brine circuit 30 and the refrigerant circulating in the refrigerant circuit 10. As a result, the refrigerant takes heat from the brine and evaporates, and the brine is cooled. The evaporated refrigerant becomes superheated steam that is slightly overheated from the saturation temperature and travels to the suction portion of the compressor 101. A low pressure sensor 72 (first pressure detector) is provided between the first evaporator 104 and the compressor 101.

  The low-pressure sensor 72 detects the pressure of the refrigerant in the superheated steam state passing between the first evaporator 104 and the compressor 101.

  The second evaporator refrigerant pipe 20 is branched from a branch part 201 provided in the refrigerant pipe between the condenser 102 and the first expansion valve 103, and is a connection part provided in the middle of the compression mechanism of the compressor 101. Connected to a certain intermediate connection unit 205. The second evaporator refrigerant pipe 20 includes a second evaporator 204 provided in the middle, and a second expansion valve 203 having an adjustable opening degree provided between the branch portion 201 and the second evaporator 204. Prepare.

  Similar to the first expansion valve 103, the second expansion valve 203 is an electronic expansion valve driven by, for example, a stepping motor, and freely adjusts the opening degree by changing the number of pulses of the stepping motor. By the expansion of the second expansion valve 203, the high-pressure liquid refrigerant becomes a higher-temperature / high-pressure medium-temperature / medium-pressure refrigerant than the refrigerant after passing through the first expansion valve 103, and is sent to the second evaporator 204.

  The reason why the refrigerant after passing through the second expansion valve 203 is higher in temperature and pressure than the refrigerant after passing through the first expansion valve 103 will be described below. The refrigerant in the first evaporator 104 goes to the suction part of the compressor 101, and the refrigerant in the second evaporator 204 goes to the intermediate connection part 205 which is a connection part provided in the middle of the compression mechanism of the compressor 101. . Since the pressure in the intermediate connection portion 205 is naturally higher than the pressure in the suction portion of the compressor 101, the refrigerant in the second evaporator 204 is higher in pressure than the refrigerant in the first evaporator 104, and the evaporation temperature is also higher. It becomes.

  Similarly to the first evaporator 104, the second evaporator 204 is, for example, a plate heat exchanger, and exchanges heat between the brine circulating in the second brine circuit 40 and the refrigerant passing through the second evaporator refrigerant pipe 20. . As a result, the refrigerant takes heat from the brine and evaporates, and the brine is cooled. The evaporated refrigerant becomes superheated steam that is slightly overheated from the saturation temperature and travels toward the intermediate connection portion 205. An intermediate pressure sensor 62 (second pressure detector) is provided between the second evaporator 204 and the intermediate connector 205.

  The intermediate pressure sensor 62 detects the pressure of the refrigerant in the superheated steam state passing between the second evaporator 204 and the intermediate connection portion 205.

  The first brine circuit 30 is a circuit for cooling an object to be cooled, which is provided separately from the refrigerant circuit 10 that bears the refrigeration cycle, and is connected to the first evaporator 104. The brine in the first brine circuit 30 that has cooled and absorbed the temperature of the object to be cooled by heat exchange between the brine in the first brine circuit 30 and the refrigerant in the refrigerant circuit 10 by the first evaporator 104. Is cooled. A first brine temperature sensor 51 (first cooled object temperature detecting unit) that detects a brine temperature Tb1 of the outlet unit is provided at the outlet of the first evaporator 104 of the first brine circuit 30.

  The first brine temperature sensor 51 uses a platinum thermometer that uses a platinum resistance thermometer when precise brine temperature control is required, such as a refrigeration apparatus (semiconductor chiller) for semiconductor manufacturing equipment. The temperature Tb1 is detected.

  The second brine circuit 40 is a circuit provided separately from the refrigerant circuit 10 that bears the refrigeration cycle, and cools an object to be cooled that is different from the first brine circuit 30. The second brine circuit 40 is connected to the second evaporator 204. The second brine circuit in which the brine in the second brine circuit 40 and the refrigerant in the second evaporator refrigerant pipe 20 are heat-exchanged by the second evaporator 204, thereby cooling the object to be cooled and absorbing heat and increasing the temperature. The brine in 40 is cooled. A second brine temperature sensor 61 (second cooled object temperature detection unit) that detects a brine temperature Tb2 of the outlet unit is provided at the outlet of the second evaporator 204 of the second brine circuit 40.

  Similarly to the first brine temperature sensor 51, the second brine temperature sensor 61 uses a platinum thermometer using a platinum resistance thermometer when precise brine temperature control is required, such as a semiconductor chiller. The temperature Tb2 is detected.

  Thus, in the refrigeration apparatus 1 according to the present embodiment, the object to be cooled is cooled by the first brine circuit 30 and the second brine circuit 40. Therefore, since the piping length of the refrigerant circuit 10 can be suppressed, the apparatus can be miniaturized and the degree of freedom of the installation place of the refrigeration apparatus 1 can be increased.

  When the control target value of the brine temperature Tb1 is T1 ° C. and the temperature control dead zone of Tb1 is, for example, ± 0.1 ° C., the first expansion valve control unit 50 detects that the Tb1 detected by the first brine temperature sensor 51 is (T1 + 0). .1) When higher than [deg.] C., the cooling capacity is increased by increasing the opening of the first expansion valve 103 and increasing the flow rate of refrigerant to the first evaporator 104, and from (T1-0.1) [deg.] C. If it is lower, the cooling capacity is reduced by reducing the flow rate of the refrigerant to the first evaporator 104 by reducing the opening of the first expansion valve, and the brine temperature of the first brine circuit is controlled to be constant. The dead zone for temperature control of Tb1 corresponds to the brine temperature change width per pulse of the first expansion valve 103. Moreover, the brine temperature control target value T1 can be set to an arbitrary temperature within the range of the capacity of the refrigeration apparatus 1, for example, between −10 ° C. and 60 ° C.

  When the control target value of the brine temperature Tb2 is T2 ° C. and the dead zone of the temperature control of Tb2 is, for example, ± 0.1 ° C., the second expansion valve control unit 60 determines that the Tb2 detected by the second brine temperature sensor 61 is (T2 + 0). .1) When higher than [deg.] C., the cooling capacity is increased by increasing the opening of the second expansion valve 203 and increasing the flow rate of refrigerant to the second evaporator 204, and from (T2-0.1) [deg.] C. Is lower, the cooling capacity is decreased by decreasing the refrigerant flow rate to the second evaporator 204 by reducing the opening of the second expansion valve 203, and the brine temperature of the second brine circuit 40 is controlled to be constant. As in the case of the temperature control of Tb1, the dead zone of the temperature control of Tb2 corresponds to the brine temperature change width per pulse of the second expansion valve 203. Moreover, the brine temperature control target value T2 can be set to any temperature within the range of the capacity of the refrigeration apparatus 1, for example, between 30 ° C and 100 ° C.

  However, the set temperature needs to satisfy T2> T1. As described above, since the refrigerant after passing through the second expansion valve 203 is hotter than the refrigerant after passing through the first expansion valve 103, the temperature of the brine that is cooled by heat exchange with the refrigerant is also the second evaporator 204. This is because the brine temperature Tb2 in the second brine circuit 40 connected to the second brine circuit 40 is higher than the brine temperature Tb1 in the first brine circuit 30 connected to the first evaporator 104.

  The second expansion valve control unit 60 further passes through the second evaporator 204 using the pressure of the refrigerant gas passing between the second evaporator 204 and the intermediate connection unit 205 detected by the intermediate pressure sensor 62. By calculating the evaporation temperature Tv2, which is the temperature when the refrigerant is a saturated gas in the second evaporator 204, it functions as a second evaporation temperature detector. The second expansion valve control unit 60 opens the upper limit as the upper limit of the opening of the second expansion valve 203 so that the temperature difference between the evaporation temperature Tv2 and the brine temperature Tb2 of the second brine circuit 40 is within a predetermined range. Set the degree. The setting of the upper limit opening will be described in detail later.

  The compressor control unit 70 controls the operation of the compressor 101. The compressor controller 70 further uses the refrigerant gas pressure detected by the low-pressure sensor 72 to evaporate the refrigerant that passes through the first evaporator 104 as a saturated gas in the first evaporator 104. By calculating Tv1, it functions as a first evaporation temperature detector. The compressor control unit 70 is calculated from the pressure of the refrigerant gas detected by the low-pressure sensor 72 when the control target value of the evaporation temperature Tv1 is T3 ° C. and the dead zone of the temperature control of Tv1 is ± eg 1.0 ° C. When Tv1 is higher than (T3 + 1.0) ° C., Tv1 is decreased by increasing the rotation speed N of the compressor 101 and lowering the pressure at the suction portion of the compressor 101, and (T3-1.0) ° C. If it is lower than that, Tv1 is increased by decreasing the rotation speed N of the compressor 101 and increasing the pressure at the suction portion of the compressor 101, and Tv1 is controlled to be constant. The dead zone of Tv1 temperature control corresponds to the evaporation temperature change width per step of the compressor rotation speed.

  In the refrigeration apparatus 1 according to the present embodiment, the saturation temperatures corresponding to the refrigerant gas pressures detected by the low pressure sensor 72 and the intermediate pressure sensor 62 are set as the refrigerant evaporation temperature Tv1 and second refrigerant temperature in the first evaporator 104, respectively. The reason why the refrigerant evaporating temperature Tv2 in the evaporator 204 is set is that it is difficult to actually measure the refrigerant evaporating temperatures Tv1 and Tv2 with a temperature sensor.

  In FIG. 1, the first expansion valve control unit 50, the second expansion valve control unit 60, and the compressor control unit 70 are illustrated separately, but one controller is used for the first expansion valve control unit 50, Of course, the second expansion valve control unit 60 and the compressor control unit 70 may function.

  In the refrigeration apparatus 1 of the present embodiment, unlike the refrigeration apparatus constituting the conventional multi-cooling system, the refrigerant that has passed through the first evaporator 104 is guided to the suction portion of the compressor 101, and the second evaporator 204 is The passed refrigerant is guided to the intermediate connection portion 205. Therefore, the control of the first expansion valve 103 and the control of the second expansion valve 203 do not interfere. This is illustrated in the following example.

  In this example, from the equilibrium state of a constant load where the rotation speed of the compressor 101 is N, the opening degree of the first expansion valve 103 is EV1, and the opening degree of the second expansion valve 203 is stable at EV2, the second evaporator Since the brine temperature on the outlet side of the second evaporator 204 of the second brine circuit 40 has increased due to the increase in the load of 204, the second expansion valve controller 60 performs the second expansion in order to increase the cooling capacity of the second evaporator 204. It is assumed that the opening degree of the valve 203 is increased (see FIG. 1).

  As the opening degree of the second expansion valve 203 increases, the refrigerant circulation amount Gev2 flowing through the second evaporator 204 increases. At this time, the refrigerant circulation amount Gcout discharged from the compressor 101 is increased by an increase in Gev2. However, since the refrigerant corresponding to the increase in Gev2 bypasses the second evaporator refrigerant pipe 20 and flows into the intermediate connection portion 205, the refrigerant circulation amount Gcin sucked into the compressor 101 is hardly affected.

  The refrigerant circulation amount Gev1 flowing through the first evaporator 104 is equal to the compressor suction refrigerant circulation amount Gcin. That is, since the refrigerant circulation amount Gev1 flowing through the first evaporator 104 hardly changes unless the compressor suction refrigerant circulation amount Gcin changes substantially, even if the opening of the second expansion valve 203 increases, the first evaporator The ability of 104 hardly changes. Therefore, it is not necessary to change the opening degree of the first expansion valve 103. Further, since the evaporation temperature of the first evaporator 104 hardly changes, it is not necessary to change the rotation speed N of the compressor 101 in order to control the evaporation temperature to be constant.

  That is, even if the opening degree of the second expansion valve 203 is changed by the second expansion valve control unit 60 in order to cope with the load fluctuation of the second evaporator 204, the interference with the capacity of the first evaporator 104 is extremely small. Therefore, the frequency of the flow rate adjustment by the first expansion valve 103 is reduced, and the occurrence of hunting associated with the flow rate change of the first expansion valve 103 is suppressed. Therefore, the stability of the brine temperature is improved, and as a result, the controllability of the brine temperature is also improved.

  As described above, according to the refrigeration apparatus 1 according to the present embodiment, the refrigerant that has passed through the second evaporator 204 bypasses the second evaporator refrigerant pipe 20 and flows into the intermediate connection portion 205. . Therefore, the change in the refrigerant flow rate to the second evaporator 204 due to the change in the opening of the second expansion valve 203 is the refrigerant in the refrigerant circuit 10 that passes through the first evaporator 104 and flows into the suction portion of the compressor 101. Has little effect on the circulation rate. Therefore, as compared with the refrigeration apparatus constituting the conventional multi-cooling system, the occurrence of hunting of the first expansion valve 103 accompanying the flow rate change is suppressed, so that the brine temperature controllability can be improved.

  (Principle of setting the upper limit opening of the second expansion valve) FIG. 2 is a diagram showing the relationship between the opening of the second expansion valve 203 and the cooling capacity of the second brine circuit 40 in the refrigeration apparatus 1.

  As the opening degree of the second expansion valve 203 (corresponding to the number of pulses of the stepping motor in this embodiment) sequentially increases from 0 (fully closed), the refrigerant circulation amount Gm flowing through the second evaporator 204 increases. The amount of heat that the refrigerant receives in the second evaporator 204, that is, the capacity Qr of the refrigerant, is a difference h2-h1 between the specific enthalpy h1 of the refrigerant at the inlet of the second evaporator 204 and the specific enthalpy h2 of the refrigerant at the outlet of the second evaporator 204. Assuming that ΔH, since Qr = Gm · ΔH, when the refrigerant circulation amount Gm flowing through the second evaporator 204 increases, Qr also increases (curve OB).

  At this time, as the Gm increases, the refrigerant pressure at the intermediate connection portion 205 increases, and the refrigerant evaporation temperature Tv2 in the second evaporator 204 rises (curve CD). The heat transfer between the brine and the refrigerant in the second evaporator 204, that is, the capacity Qe of the second evaporator 204 is the average heat passage rate K, the heat transfer area A, and the brine temperature at the inlet of the second evaporator 204 Tb2. (Line DD ′), where ΔT is the temperature difference (Tb2−Tv2) between the brine and the refrigerant, Qe = K · A · ΔT. Therefore, when the evaporation temperature of the refrigerant in the second evaporator 204 increases, that is, when ΔT decreases, the capacity Qe of the second evaporator 204 decreases (curve EF).

  The cooling capacity of the second brine circuit 40 by the refrigeration apparatus 1 is determined by the smaller one of the capacity Qr of the refrigerant and the capacity Qe of the second evaporator 204 (curve OJF). Therefore, when the capacity of the refrigerant exceeds the capacity of the heat exchanger (Qr> Qe), that is, the opening degree of the second expansion valve 203 corresponds to Th ° C. which is the value of ΔT when Qr = Qe. When Pth is exceeded, the cooling capacity decreases as the second expansion valve 203 is opened. The value of Th is naturally different when the refrigerant performance characteristics, the average heat transfer rate K, and the heat transfer area A of the second evaporator 204 are different, but are approximately about 5 ° C. to 15 ° C. It is.

  For the reason described above, the second expansion valve 203 needs to set an upper limit opening. The upper limit opening of the second expansion valve 203 may be the opening when ΔT = Th. When the refrigerant circulation amount Gev1 flowing through the first evaporator 104 increases as the opening of the first expansion valve 103 increases, the compressor control unit 70 increases the rotation speed N of the compressor 101 to compress the refrigerant. Since the pressure at the suction portion of the machine 101 is lowered, the evaporation temperature of the first evaporator 104 does not increase. Therefore, unlike the second expansion valve 203, it is not necessary to set an upper limit opening degree for the first expansion valve 103.

  (Control of the second expansion valve) The upper limit opening of the second expansion valve 203 is set by setting the temperature difference ΔT between the brine and the refrigerant to be less than a predetermined value (10 ° C. in the present embodiment) corresponding to the Th. The brine temperature control of the second brine circuit is performed by adjusting the opening degree of the second expansion valve 203. Details will be described below.

  FIG. 3 is a flowchart for explaining the control of the second expansion valve 203. When the refrigeration apparatus 1 is activated, the second expansion valve control unit 60 calculates the evaporation temperature Tv2 of the refrigerant passing through the second evaporator 204 using the pressure detected by the intermediate pressure sensor 62, and the second brine ΔT is calculated by subtracting Tv2 from the brine temperature Tb2 at the outlet of the second evaporator 204 of the second brine circuit 40 detected by the temperature sensor 61 (step S1).

  When ΔT is less than a predetermined value (10 ° C. in the present embodiment) (YES in step S1), the second expansion valve control unit 60 decreases the opening of the second expansion valve 203 (step S2). When ΔT is 10 ° C. or more (NO in step S1), the process proceeds to step S5, and brine temperature control is performed by adjusting the opening of the second expansion valve 203.

  If ΔT becomes 10 ° C. or more by reducing the opening of second expansion valve 203 (YES in step S3), second expansion valve control unit 60 sets the opening to the upper limit opening (step S4). . If ΔT is less than 10 ° C. (NO in step S3), the second expansion valve control unit 60 repeats steps S2 and S3, and decreases the opening of the second expansion valve 203 until ΔT becomes 10 ° C. or more. An upper limit opening is set (step S4).

  If ΔT is equal to or higher than the predetermined value of 10 ° C., the second expansion valve control unit 60 controls the brine temperature Tb2 by adjusting the opening of the second expansion valve 203. Hereinafter, the brine temperature control target value is set to T2 ° C., and the dead zone for temperature control is set to ± 0.1 ° C. When the temperature Tb2 detected by the second brine temperature sensor 61 is higher than (T2 + 0.1) ° C. (YES in step S5), the second expansion valve control unit 60 increases the refrigerant flow rate to the second evaporator 204. In order to increase the cooling capacity, the opening of the second expansion valve 203 is increased up to the upper limit opening set in step S4 (step S6).

  When Tb2 is equal to or lower than (T2 + 0.1) ° C. (NO in step S5), when Tb2 = (T2 ± 0.1) ° C. (YES in step S7), the brine temperature Tb2 is within the target temperature range, that is, Since the cooling capacity of the two evaporator 204 is appropriate, the second expansion valve control unit 60 maintains the opening degree of the second expansion valve 203 (step S8).

  When Tb2 is lower than (T2-0.1) ° C. (NO in step S7), the second expansion valve control unit 60 reduces the cooling capacity by decreasing the refrigerant flow rate to the second evaporator 204. The opening degree of the second expansion valve 203 is reduced (step S9).

  In any of steps S6, S8, and S9, the process returns to step S1, and the second expansion valve control unit 60 calculates ΔT. Thus, steps S1 to S9 are repeated during operation of the refrigeration apparatus 1.

  As described above, according to the refrigeration apparatus 1 according to the present embodiment, the second expansion valve control unit 60 includes the brine temperature Tb2 of the second brine circuit 40 and the evaporation temperature Tv2 of the refrigerant passing through the second evaporator. When the temperature difference ΔT is less than a predetermined value (10 ° C. in this embodiment), the upper limit opening of the second expansion valve 203 is set by reducing the opening of the second expansion valve 203. Thereby, the cooling capacity of the second evaporator 204 is maximized.

  (First Expansion Valve and Rotational Speed Control of Compressor) FIG. 4 is a flowchart for explaining the control related to the opening degree setting of the first expansion valve 103 and the rotational speed control of the compressor 101. The control target value of the brine temperature Tb1 is T1 ° C., the Tb1 temperature control dead zone is ± 0.1 ° C., the control target value of the evaporation temperature Tv1 is T3 ° C., and the Tv1 temperature control dead zone is ± 1.0 ° C.

  When the refrigeration apparatus 1 is activated, the first expansion valve control unit 50 controls the brine temperature Tb1 by adjusting the opening degree of the first expansion valve 103. When the temperature Tb1 detected by the first brine temperature sensor 51 is higher than (T1 + 0.1) ° C. (YES in step S101), the first expansion valve control unit 50 increases the refrigerant flow rate to the first evaporator 104. In order to increase the cooling capacity, the opening degree of the first expansion valve 103 is increased (step S102).

  When Tb1 is equal to or lower than (T1 + 0.1) ° C. (NO in step S101), when Tb1 = (T1 ± 0.1) ° C. (YES in step S104), the brine temperature Tb1 is within the target temperature range, that is, Since the cooling capacity of the one evaporator 104 is appropriate, the first expansion valve control unit 50 maintains the opening degree of the first expansion valve 103 (step S105).

  When Tb1 is less than (T1-0.1) ° C. (NO in step S104), the first expansion valve control unit 50 decreases the cooling capacity by decreasing the refrigerant flow rate to the first evaporator 104. The opening degree of the first expansion valve 103 is reduced (step S107).

  When the opening degree of the first expansion valve 103 changes, the pressure at the suction portion of the compressor 101 changes and the evaporation temperature Tv1 also changes. Therefore, in order to control to Tv1 = (T3 ± 1.0), the compressor control unit 70 controls the rotation speed N of the compressor 101 according to the opening degree change of the first expansion valve 103. That is, when the opening degree of the first expansion valve 103 increases (step S102), the compressor control unit 70 increases the rotational speed N of the compressor 101 and decreases the pressure at the suction unit of the compressor 101 (step S102). S103) When the opening degree of the first expansion valve 103 is maintained (step S105), the rotation speed N of the compressor 101 is maintained (step S106), and the opening degree of the first expansion valve 103 is reduced. (Step S107), the rotational speed N of the compressor 101 is reduced to increase the pressure at the suction portion of the compressor 101 (Step S108).

  In any of steps S103, S106, and S108, the compressor control unit 70 calculates Tv1 using the pressure of the refrigerant gas detected by the low-pressure sensor 72, and results of control of the rotational speed N of the compressor 101. , Tv1 is determined to be within the range of (T3 ± 1.0). When Tv1 is higher than (T3 + 1.0) ° C. (YES in step S109), the compressor control unit 70 increases the rotation speed N of the compressor 101 and decreases the pressure at the suction unit of the compressor 101. Tv1 is lowered (step S110).

  When Tv1 is equal to or lower than (T3 + 1.0) ° C. (NO in step S109), when Tv1 = (T3 ± 1.0) ° C. (YES in step S111), Tv1 is within the target temperature range. The machine control unit 70 maintains the rotational speed N of the compressor 101 (step S112).

  When Tv1 is less than (T3-1.0) ° C. (NO in step S111), the compressor control unit 70 increases the pressure at the suction unit of the compressor 101 by reducing the rotation speed N of the compressor 101. To increase Tv1 (step S113).

  In any of steps S110, S112, and S113, the process returns to step S101, and the first expansion valve control unit 50 controls the brine temperature Tb1. In this way, steps S101 to S113 are repeated during operation of the refrigeration apparatus 1.

  As described above, according to the refrigeration apparatus 1 according to the present embodiment, the evaporation temperature of the refrigerant passing through the first evaporator 104 is controlled to be within a predetermined range. Therefore, since the evaporation temperature of the refrigerant passing through the first evaporator 104 downstream of the first expansion valve 103 is increased by increasing the opening degree of the first expansion valve 103, the temperature difference from the brine is reduced. It is possible to prevent the cooling capacity from being lowered.

  The refrigeration apparatus 1 according to the embodiment of the present invention has been described above, but the present invention is not limited to this, and for example, the following modified embodiment can be taken.

  (1) In the above embodiment, the saturation temperature corresponding to the pressure of the refrigerant gas detected by the low pressure sensor 72 and the intermediate pressure sensor 62 is set to the evaporation temperature Tv1 and the second evaporation of the refrigerant in the first evaporator 104, respectively. The evaporation temperature Tv2 of the refrigerant in the vessel 204 is set. Instead of the low pressure sensor 72 and the intermediate pressure sensor 62, temperature sensors are provided between the first expansion valve 103 and the first evaporator 104 and between the second expansion valve 203 and the second evaporator 204, respectively. The temperatures detected by the temperature sensor may be used as Tv1 and Tv2, respectively.

  (2) In the above embodiment, the compressor 101 is a scroll compressor. However, the compression mechanism of the compressor is not limited to the scroll type, and if an intermediate connection portion is provided in the middle of the compression mechanism, for example, A compressor having a compression mechanism different from a scroll compressor such as a rotary compressor may be used.

It is a schematic diagram which shows the freezing apparatus which concerns on one Embodiment of this invention. It is a figure which shows the relationship between the opening degree of a 2nd expansion valve, and the cooling capacity of the 2nd brine circuit in a freezing apparatus. It is a flowchart for demonstrating control of a 2nd expansion valve. It is a flowchart for demonstrating the control which concerns on the opening degree setting of a 1st expansion valve, and the rotation speed control of the compressor 101. FIG. It is a schematic diagram which shows an example of the conventional freezing apparatus which comprises a multi-cooling system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 10 Refrigerant circuit 101 Compressor 102 Condenser 103 1st expansion valve 104 1st evaporator 20 2nd evaporator refrigerant piping 201 Branch part 203 2nd expansion valve 204 2nd evaporator 205 Intermediate connection part 30 1st brine Circuit 40 Second brine circuit 50 First expansion valve control unit (first evaporation temperature detection unit)
51 1st brine temperature sensor (1st to-be-cooled object temperature detection part)
60 Second expansion valve control unit (second evaporation temperature detection unit)
61 2nd brine temperature sensor (2nd to-be-cooled object temperature detection part)
62 Intermediate pressure sensor (second evaporation temperature detector, second pressure detector)
70 Compressor controller 72 Low pressure sensor (first evaporating temperature detector, first pressure detector)

Claims (5)

A refrigerant circulates in a circuit in which a compressor (101), a condenser (102), a first expansion valve (103) whose opening degree can be adjusted, and a first evaporator (104) are connected by a refrigerant pipe. A refrigerant circuit (10) for
A compression mechanism of the compressor (101) branched from a branch (201) provided in a refrigerant pipe between the condenser (102) and the first expansion valve (103) in the refrigerant circuit (10). A second evaporator refrigerant pipe (20) which is a refrigerant pipe connected to an intermediate connection part (205) which is a connection part provided in the middle of
A second evaporator (204) provided in the middle of the second evaporator refrigerant pipe;
A second expansion valve (203) with adjustable opening, provided in the refrigerant pipe between the branch (201) and the second evaporator (204);
A first object to be cooled temperature detector (51) for detecting a temperature of the first object to be cooled cooled by the first evaporator (104);
A second object to be cooled temperature detector (61) for detecting the temperature of the second object to be cooled cooled by the second evaporator (204);
Based on the temperature detected by the first object to be cooled temperature detector (51), the opening degree of the first expansion valve (103) is controlled so that the temperature of the first object to be cooled is within a predetermined range. A first expansion valve controller (50) that
Based on the temperature detected by the second cooled object temperature detection unit (61), the opening degree of the second expansion valve (203) is controlled so that the temperature of the second cooled object falls within a predetermined range. And a second expansion valve control unit (60). A first evaporating temperature detecting section (70, 72) for detecting an evaporating temperature which is a temperature when the refrigerant in the refrigerant circuit (10) is a saturated gas in the first evaporator (104);
A second evaporation temperature detector (60, 62) for detecting an evaporation temperature which is a temperature when the refrigerant in the second evaporator refrigerant pipe is a saturated gas in the second evaporator;
A compressor control unit (70) for controlling the operating state of the compressor,
The compressor control unit (70) is configured so that the evaporation temperature of the refrigerant passing through the first evaporator (104) is within a predetermined range based on the temperature detected by the first evaporation temperature detection unit (70, 72). The number of revolutions of the compressor (101) is controlled to be within,
In addition to the control, the second expansion valve control unit (60) further passes through the second evaporator (204) based on the temperature detected by the second evaporation temperature detection unit (60, 62). The refrigerating apparatus according to claim 1, wherein an upper limit opening is set as an upper limit of the opening of the second expansion valve (203) so that an evaporation temperature of the refrigerant to be within a predetermined range.   When the temperature difference between the temperature of the second object to be cooled and the evaporation temperature of the refrigerant passing through the second evaporator (204) becomes less than a predetermined value, the second expansion valve control unit (60) The refrigeration apparatus according to claim 2, wherein the upper limit opening is set by reducing the opening of the second expansion valve (203). The first evaporating temperature detecting unit (70, 72) detects the pressure of the refrigerant gas passing through the refrigerant pipe between the first evaporator (104) and the suction unit of the compressor (101). 1 pressure detector (72), the evaporation temperature is calculated based on the pressure,
The second evaporation temperature detector (60, 62) detects a pressure of the refrigerant gas passing through the refrigerant pipe between the second evaporator (204) and the intermediate connector (205). The refrigeration apparatus according to claim 2, further comprising a detection unit (62), wherein the evaporation temperature is calculated based on the pressure. A brine circuit connected to the first evaporator (104), wherein the brine in the brine circuit and the refrigerant in the refrigerant circuit (10) are heat-exchanged in the first evaporator (104). A first brine circuit (30) in which the brine is cooled;
A brine circuit connected to the second evaporator (204), wherein the brine in the brine circuit and the refrigerant passing through the second evaporator refrigerant pipe (20) are in the second evaporator (204). A second brine circuit (40) in which the brine is cooled by heat exchange, and
The first object-to-be-cooled temperature detector (51) detects a brine temperature at the outlet of the first evaporator (104) of the first brine circuit (30),
The said 2nd to-be-cooled object temperature detection part (61) detects the brine temperature of the exit part of the said 2nd evaporator (204) of the said 2nd brine circuit (40). Refrigeration equipment.

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