JP4809076B2 - Refrigeration system and method of operating refrigeration system - Google Patents

Description

  The present invention relates to a refrigeration system that appropriately controls the degree of supercooling of a refrigerator or the like by a dual refrigeration cycle that exchanges heat between two refrigeration cycles, and improves the capacity and COP (coefficient of performance), and an operation method thereof. It is.

Conventionally, a refrigeration apparatus including a supercooling device having a supercooling heat exchanger in a refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected is known. In the refrigerant circuit of this refrigeration apparatus, the high-temperature and high-pressure refrigerant discharged from the compressor is condensed in a condenser, and the condensed refrigerant is supercooled in a supercooling heat exchanger by a cooling heat source independent of the refrigerant circuit, Refrigerant circulation is performed after the pressure is reduced by the expansion valve, evaporated by the evaporator, and then returned to the compressor. Since the decompression process can be regarded as an adiabatic change, the enthalpy of the refrigerant before evaporation is substantially equal to the enthalpy of the refrigerant after supercooling. Therefore, the enthalpy difference (the amount of change in enthalpy) of the refrigerant is increased by the amount of supercooling between the inlet side and the outlet side of the evaporator constituting the refrigeration cycle. Since the amount of heat absorbed by the refrigerant in the indoor heat exchanger is increased as compared with the case where no supercooling device is provided, the performance of the refrigeration device is improved. (For example, see Patent Document 1)
Japanese Patent Laying-Open No. 2005-233559 (FIGS. 2 and 3)

  However, the conventional supercooling device has a problem that the degree of supercooling cannot be controlled properly depending on the operating conditions of the refrigeration device such as the outside air condition, and the capacity and COP cannot be improved reliably. .

  Also, since it is necessary to place temperature detection means in the piping of the refrigeration system in order to obtain the degree of supercooling of the refrigeration system, workability at the time of new installation or renewal is poor, especially in the case of a remote condenser type refrigeration system However, it is necessary to install the condenser of the refrigeration apparatus outside and to dispose the supercooling heat exchanger in the machine room, and there is a problem that the temperature detection means must be wired between the machine room and the outside.

  In addition, when the cooling capacity of the supercooling device is excessive, the degree of supercooling increases and the refrigerant at the outlet of the expansion valve of the refrigeration device becomes a liquid phase, which deteriorates the heat transfer performance of the evaporator. There is a problem that the COP is lowered, the refrigerant flow is further hunted, the operation state of the refrigeration cycle becomes unstable, and a stable operation cannot be obtained.

  The present invention has been made to solve the above-described problems in the prior art, and controls the supercooling device so that the degree of supercooling of the refrigeration device and the like is always an appropriate value. An object is to obtain a refrigeration system that can perform stable control and can save energy.

  In addition, since the present invention estimates the degree of supercooling of the refrigeration device from the operating state of the supercooling device, etc., it is not necessary to wire the temperature detection means between the machine room and the outside, and the construction when the supercooling device is installed can be performed. The purpose is to obtain an easy refrigeration system.

  Further, the present invention controls the operation state of the refrigeration apparatus and the like by controlling the operation state of the supercooling apparatus based on the operation state of the refrigeration apparatus so that the refrigerant at the outlet of the expansion valve of the refrigeration apparatus is surely in a two-phase state. It is an object of the present invention to obtain a method for operating a refrigeration system that makes it possible to constantly stabilize the operation of the system and to perform a highly efficient operation at all times.

The refrigeration system according to the present invention includes:
A first refrigeration cycle having a first compressor, a first heat exchanger, a first throttling means, and a second heat exchanger, and circulating a first refrigerant therein;
A second refrigeration cycle having a second compressor, a third heat exchanger, a second throttling means, and a fourth heat exchanger, and circulating a second refrigerant therein;
First low pressure detection means for detecting the pressure on the low pressure side of the first compressor of the first refrigeration cycle or first evaporation temperature detection means for detecting the evaporation temperature of the first refrigeration cycle;
First control means for controlling the operation of the first refrigeration cycle based on the detection value of the first low-pressure detection means or the first evaporation temperature detection means;
Second low pressure detection means for detecting the pressure on the low pressure side of the second compressor of the second refrigeration cycle or second evaporation temperature detection means for detecting the evaporation temperature of the second refrigeration cycle;
Second control means for controlling the operation of the second refrigeration cycle based on the detection value of the second low-pressure detection means or the second evaporation temperature detection means ;
With
The fourth heat exchanger is a refrigerant-refrigerant heat exchanger that performs heat exchange between the refrigerant and the refrigerant, and the first throttling means from the outlet of the first heat exchanger of the first refrigeration cycle. Inserted in any position of the flow path to the inlet, configured so that the first refrigeration cycle and the second refrigeration cycle can exchange heat with each other,
Based on the operating state of the first refrigeration cycle, the first control means and the second control means are connected in a wired or wireless manner so as to control the operation of the second refrigeration cycle. Configured to be controllable,
The second control means is configured to detect the fourth heat exchanger of the first refrigeration cycle based on a detection value of the second low pressure detection means or the second evaporation temperature detection means of the second refrigeration cycle. Refrigerant temperature at any position in the flow path from the outlet side of the first throttle means or the saturation temperature of the two-phase refrigerant flowing in the first heat exchanger and the first refrigeration cycle A function of calculating a degree of supercooling that is a temperature difference from the refrigerant temperature at any position in the flow path from the outlet side of the fourth heat exchanger to the inlet of the first throttle means; The operation of the second refrigeration cycle is controlled based on the obtained refrigerant temperature or degree of supercooling.

  In the refrigeration system according to the present invention, the first control means and the second control means are wired or wired so that the operation of the second refrigeration cycle can be controlled based on the operating state of the first refrigeration cycle. It is configured so that it can be connected wirelessly and controlled in a coordinated manner, and the second refrigeration cycle can be controlled so that the degree of supercooling of the first refrigeration cycle is always an appropriate value. Stable control can be performed even under such operating conditions, and a refrigeration system that can save energy can be obtained.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram of a refrigeration system showing Embodiment 1 of the present invention. First, the operation of the refrigeration apparatus will be described. In the figure, 1 is a compressor for refrigeration or freezing (first compressor), 2 is an outdoor heat exchanger for refrigeration or freezing (first heat exchanger), 4 is a receiver for refrigeration or freezing, Reference numerals 5a and 5b denote refrigeration or freezing throttling means (first throttling means), and 6a and 6b denote refrigeration or freezing indoor heat exchangers (second heat exchangers), which are connected to the refrigerant pipes 13 and 14 respectively. Are connected to each other to form a refrigeration or refrigeration cycle (first refrigeration cycle) 20, and the refrigerant flowing in the refrigeration or refrigeration cycle 20 is caused by the action of the outdoor fan 3 for refrigeration or refrigeration. Heat is radiated to the outdoor air by the refrigeration or freezing outdoor heat exchanger 2, and is absorbed by the refrigeration or freezing indoor heat exchangers 6a and 6b by the action of the refrigeration or freezing indoor fans 7a and 7b to cool indoors. Supply.

  1 shows a case where the refrigerant absorbs heat from the air in the refrigeration or freezing outdoor heat exchanger 2, but the present invention is not limited to this, and is configured to absorb heat from water, refrigerant, brine, or the like. May be. The outdoor fan 3 for refrigeration or freezing may be a pump or the like. In addition, FIG. 1 shows a configuration example when there are two indoor units. However, a plurality of units or three units may be used, and even if the capacity of each indoor unit varies from large to small, all of them have the same capacity. But you can.

  42 is an outdoor air temperature detecting means for detecting the temperature of the outdoor air, 31 is a refrigeration or freezing high pressure pressure detecting means for detecting the high pressure on the discharge side of the compressor 1, and is detected by the outdoor air temperature detecting means 42. Based on the outdoor air temperature, the control device (first control means) 51 controls the number of rotations of the outdoor fan 3 for refrigeration or freezing so that the high pressure for refrigeration or freezing falls within a desired range. Yes.

  Reference numeral 32 denotes a refrigeration or refrigeration low pressure detection means (first low pressure detection means) for detecting the low pressure on the suction side of the compressor 1, and the refrigeration or refrigeration refrigeration low pressure based on the detected low pressure. The control device 51 controls the operating capacity of the refrigeration or refrigeration compressor 1 so that is within a desired range.

  The control target values for the high pressure and low pressure of the refrigeration or freezing refrigeration cycle 20 are the measured values of the outdoor air temperature detection means 42, the refrigeration or freezing high pressure detection means 31, and the refrigeration or freezing low pressure detection means 32. Is calculated by the calculation unit 62 of the control device 51 and stored in the storage unit 61.

  Next, the configuration and operation of the supercooling device will be described. The supercooling device includes a supercooling compressor (second compressor) 8, a supercooling outdoor heat exchanger (third heat exchanger) 9, and a supercooling throttle means (second throttle means). 11 and a supercooling heat exchanger (fourth heat exchanger) 12 are connected by a refrigerant pipe to constitute a supercooling refrigeration cycle (second refrigeration cycle) 21. The refrigerant flowing in the supercooling refrigeration cycle 21 radiates heat to the outdoor air in the supercooling outdoor heat exchanger 9 by the action of the supercooling outdoor fan 10, and the refrigeration refrigeration cycle in the supercooling heat exchanger 12. The refrigerant that absorbs heat from the refrigerant flowing in the refrigerant 20 cools the refrigerant that flows in the refrigeration cycle 20 to give a degree of supercooling.

  The subcooling refrigeration cycle 21 and the above-described refrigeration or refrigeration cycle 20 are independent refrigerant circuits, and the refrigerant flowing through them may be of the same type or of different types. However, the heat is exchanged in the subcooling heat exchanger 12 without being mixed. The supercooling throttling means 11 may use either an inexpensive refrigerant flow rate control means such as a capillary tube or a precise flow rate control means using an electronic expansion valve.

  FIG. 1 shows a case where the refrigerant absorbs heat from the air in the subcooling outdoor heat exchanger 9. However, the present invention is not limited to this, and is configured to absorb heat from water, refrigerant, brine, or the like. Also good. The subcooling outdoor fan 10 may be a pump or the like.

  43 is an outdoor air temperature detecting means for detecting the temperature of outdoor air, and 33 is a supercooling high pressure detecting means for detecting the high pressure on the discharge side of the compressor 8, which is detected by the outdoor air temperature detecting means 43. Based on the outdoor air temperature, the control device (second control means) 52 controls the rotation speed of the subcooling outdoor blower 10 so that the high pressure for subcooling falls within a desired range.

  34 is a subcooling low pressure detecting means (second low pressure detecting means) for detecting the low pressure on the suction side of the compressor 8, and based on the detected low pressure, the controller 52 controls the subcooling low pressure. Is controlled so as to be within a desired range.

  The control target values for the high pressure and low pressure of the supercooling refrigeration cycle 21 are based on the measured values of the outdoor air temperature detecting means 43, the supercooling high pressure pressure detecting means 33, and the supercooling low pressure pressure detecting means 34. 51 are calculated by the calculation unit 64 and stored in the storage unit 63.

  FIG. 1 shows a state in which a supercooling refrigerant temperature detection means (refrigerant temperature detection means) 41 is installed in the vicinity of the outlet of the supercooling heat exchanger 12 on the refrigeration or refrigeration cycle 20 side. However, in the description here, the supercooling refrigerant temperature detection means (refrigerant temperature detection means) 41 is not installed, and the supercooling refrigerant temperature is obtained by arithmetic processing or the like as described later. A supercooling heat exchanger outlet temperature detecting means 44 is installed in the vicinity of the outlet of the supercooling heat exchanger 12 on the supercooling refrigeration cycle 21 side. The temperature detecting means 44 is in contact with or inserted into the refrigerant pipe and detects the refrigerant temperature in the supercooling refrigeration cycle 21, and the control device 52 refrigerates the supercooling heat exchanger 12. On the basis of the temperature of the supercooling refrigerant on the outlet side of the refrigerating cycle 20 for refrigerating or refrigerating and the output of the temperature detecting means 44, the amount of throttling of the subcooling throttling means 11 is adjusted and flows into the supercooling heat exchanger 12 The amount of heat exchange in the supercooling heat exchanger 12 of the refrigeration and refrigeration cycle 20 is controlled by controlling the flow rate of the refrigerant.

  FIG. 2 is a diagram illustrating the refrigeration cycle of the refrigeration cycle 20 for refrigeration or refrigeration and the refrigeration cycle 21 for supercooling in a ph diagram. In the refrigeration or freezing refrigeration cycle 20, a ph diagram in the case where there is a supercooling action in the supercooling heat exchanger 12 is indicated by a broken line, and the supercooling in the supercooling heat exchanger 12 is The ph diagram when there is no effect is shown by a solid line. As can be seen from FIG. 2, as the degree of supercooling increases, the temperature of the refrigerant at the inlet of the refrigeration or refrigeration throttle means 5a, 5b decreases from Tr1 to Tr2, and the refrigeration or refrigeration indoor heat exchanger 6a, The enthalpy difference Δh of the refrigerant increases by this temperature difference between the inlet side and the outlet side of 6b. The degree of supercooling of the refrigeration or refrigeration cycle 20 can be obtained by subtracting the temperature of the subcooling heat exchanger outlet temperature detection means 44 from the condensation temperature obtained from the refrigeration or refrigeration high pressure detection means 31. .

  In this refrigeration or freezing refrigeration cycle 20, the amount of heat absorbed by the refrigerant in the refrigeration or freezing indoor heat exchangers 6a and 6b is increased, that is, refrigeration compared to the case where the supercooling refrigeration cycle 21 is not installed. The cooling capacity of the refrigeration cycle 20 for use or refrigeration is improved.

  Further, since the cooling capacity of the refrigeration cycle can be reduced by reducing the cooling capacity of the refrigeration or refrigeration cycle 20, the power used for circulating the refrigerant can be reduced. For this reason, when the supercooling refrigeration cycle 21 is provided, the COP of the refrigeration or refrigeration cycle 20 is higher than when the supercooling refrigeration cycle 21 is not provided.

  In addition, since the refrigerant circulation amount is reduced and the pressure loss in the piping is reduced by providing the supercooling refrigeration cycle 21, the piping size of the refrigeration or refrigeration cycle 20 can be reduced, and the workability is improved. In addition, since the pipe size is reduced, heat loss in the pipe is reduced, the performance is improved, and the amount of charged refrigerant can be reduced, so that the product cost is reduced.

  Furthermore, the lower the evaporation temperature Ter0 of the refrigeration or refrigeration cycle 20 shown in FIG. 2, the smaller the density of refrigerant sucked by the compressor, so that the refrigerant circulation amount decreases and the compression ratio increases and compression occurs. Since the machine input also increases, the COP of the refrigeration cycle 20 for refrigeration or refrigeration decreases. Since the evaporation temperature Ter1 of the subcooling refrigeration cycle 21 is higher than Ter0, the operation with supercooling in the subcooling refrigeration cycle 21 increases the COP of the entire refrigeration cycle system.

  Since the refrigerating capacity of the subcooling refrigeration cycle 21 may be any capacity that can provide supercooling for the capacity enhancement necessary for the refrigeration or freezing refrigeration cycle 20, the capacity of the compressor 8 of the subcooling refrigeration cycle 21 is A size smaller than the compressor 1 used in the refrigeration or freezing refrigeration cycle 20 is sufficient, and is, for example, about 20 to 30% or less with respect to the capacity of the compressor 1 of the refrigeration or freezing refrigeration cycle 20. Capacity.

  Further, since the refrigerant pipe 13 and the supercooling heat exchanger 12 are provided in series in the refrigeration or refrigeration cycle 20, the supercooling heat exchanger can be installed in the middle of the extension pipe. Easy to install. In addition, since the refrigerant circuit of the refrigeration or refrigeration cycle 20 and the subcooling refrigeration cycle 21 are independent, a highly reliable system can be realized without affecting the other refrigerant circuit even when trouble occurs. At the same time, since the refrigerant circuit is not complicated and independent, maintenance is easy, and maintenance costs are reduced.

  In addition, since the system can be configured only by providing the supercooling refrigeration cycle 21 separately from the refrigeration or refrigeration cycle 20 constituting the normal refrigeration or refrigeration apparatus, the existing refrigeration or refrigeration apparatus can be used as it is. By utilizing this, the refrigeration system according to the present invention can be easily constructed.

  In addition, since the control device 51 and the control device 52 can exchange information with each other via the communication line 53, it is possible to perform control in cooperation with each other. An energy saving system can be constructed.

  For example, if the ON / OFF state of the refrigeration or refrigeration compressor 1 is communicated from the control device 51 to the control device 52 and the ON / OFF timing of the subcooling compressor 8 is controlled accordingly, the subcooling compression is performed. Since there is no useless operation of the machine 8, energy is saved. In addition, after the refrigeration or refrigeration compressor 1 is started, the subcooling compressor 8 is started after waiting until the outlet refrigerant of the condenser 2 of the refrigeration or refrigeration cycle 20 becomes completely liquid refrigerant. Thus, when the refrigerant of the supercooling refrigeration cycle 21 passes through the supercooling heat exchanger 12, the heat of the refrigeration or freezing refrigeration cycle 20 can be sufficiently absorbed and evaporated, so that the supercooling refrigeration The cycle 21 can operate stably, the reliability of the system is increased, and energy saving can be ensured.

  Further, in the supercooling heat exchanger 12, heat is exchanged between the evaporation temperature of the supercooling refrigeration cycle 21 and the liquid refrigerant of the refrigeration or refrigeration cycle 20, and the performance of the supercooling heat exchanger 12 is improved. From this, it is known that the temperature difference between the supercooling refrigerant temperature at the outlet of the supercooling heat exchanger 12 of the refrigeration or refrigeration cycle 20 and the evaporation temperature of the supercooling refrigeration cycle 21 can be estimated with a certain degree of accuracy. . For example, in a certain combination, when the refrigeration cycle 20 is for refrigeration, the supercooling refrigerant temperature at the outlet of the supercooling heat exchanger 12 of the refrigeration cycle 20 is 5 ° C. added to the evaporation temperature of the supercooling refrigeration cycle 21. When the refrigeration cycle 20 is for refrigeration, the supercooling refrigerant temperature at the outlet of the supercooling heat exchanger 12 of the refrigeration cycle 20 can be estimated by adding 0 ° C. to the evaporation temperature of the supercooling refrigeration cycle 21. It has been confirmed by simulation. Therefore, when the supercooled refrigerant temperature is controlled to a constant value, the control device 51 and the control device 52 can be operated only by transmitting ON / OFF information. When considering further changes in environmental conditions and other effects in order to achieve higher performance, the control device 51 transfers to the control device 52 a low pressure control target value or an evaporation temperature control target value (or an evaporation temperature control target value) of the supercooling refrigeration cycle 21 (or By communicating the target value of the degree of supercooling), the supercooled refrigerant temperature at the outlet of the supercooling heat exchanger 12 of the refrigeration cycle 20 for refrigeration or refrigeration can be controlled to the optimum value at all times, saving energy. Increases effectiveness. Further, when the supercooling refrigerant temperature is controlled, the control device 52 uses the output of the supercooling low-pressure pressure detection means 34 of the supercooling refrigeration cycle 21 or the evaporation temperature of the supercooling refrigeration cycle 21 for refrigeration or The supercooling refrigerant temperature at the outlet of the supercooling heat exchanger 12 of the refrigeration cycle 20 or the degree of supercooling of the refrigeration or freezing refrigeration cycle 20 is obtained, and the supercooling refrigerant temperature at the outlet of the supercooling heat exchanger 12 is determined. By controlling to the optimum value, highly accurate control is possible.

  Further, the control target value of the supercooling refrigerant temperature or the control target value of the degree of supercooling of the refrigeration or refrigeration cycle 20 is communicated from the control device 51 to the control device 52, so that the refrigeration or refrigeration cycle 20 is stored. The operating capacity of the compressor 8 of the subcooling refrigeration cycle 21 can be controlled so that the refrigerant at the inlet of the refrigeration or freezing indoor heat exchangers 6a and 6b has two phases. As a result, the refrigeration or refrigeration cycle 20 can be stably operated, and the heat transfer coefficient can be increased throughout the heat exchanger, so that the cooling capacity and the COP can be reliably improved. It is also possible to turn on / off the supercooling compressor 8 using a measured value of the supercooling refrigerant temperature or a communication value of the control target value of the supercooling refrigerant temperature as a trigger.

  Next, an appropriate method for controlling the degree of supercooling will be described with reference to a refrigeration or refrigeration cycle control flowchart of FIG. 3 and a subcooling refrigeration cycle control flowchart of FIG.

  FIG. 3 shows a control operation performed by the control device 51 for refrigeration or freezing. First, the target low pressure Psrm during normal operation of the refrigeration or refrigeration cycle 20 is read (ST101). Next, Psr is measured by the low pressure detection means 32 (ST102), and the operating capacity of the compressor 1 is controlled so that the low pressure measurement value Psr approaches the target low pressure Psrm (ST103).

  Next, the control target temperature Tr2m of the subcooling refrigerant temperature Tr2 is calculated from the low pressure target value Psrm (ST104). And, by setting and controlling the control target temperature Tr2m of the supercooling refrigerant temperature Tr2 so that the refrigerant at the inlet of the refrigeration or freezing indoor heat exchanger 6a, 6b becomes two-phase, stable operation can be performed, The heat transfer coefficient is increased throughout the heat exchanger, and the cooling capacity and COP can be reliably improved.

  Actually, there is a pressure loss from the outlet of the throttle means 5a, 5b of the refrigeration or freezing refrigeration cycle 20 to the suction of the compressor 1, so the target value Tr2m of the supercooled refrigerant temperature is set taking this into consideration. By doing so, the two-phase refrigerant can surely flow into the refrigeration or freezing indoor heat exchangers 6a and 6b, and the heat exchange efficiency is improved.

  Further, when the refrigerant for refrigeration or the refrigeration cycle 20 is a non-azeotropic refrigerant mixture, the temperature varies depending on the dryness even if the two-phase refrigerant has the same pressure. By setting the target value Tr2m of the supercooled refrigerant temperature in consideration of the above, the two-phase refrigerant can surely flow into the refrigeration or refrigeration indoor heat exchangers 6a and 6b, and the heat exchange efficiency is improved.

  When the cooling load is small with respect to the cooling capacity of the refrigeration or refrigeration cycle 20, energy loss due to start / stop increases. Therefore, the cooling capacity with respect to the cooling load is estimated from the operating state of the refrigeration or refrigeration cycle 20, and the operation request level of the subcooling refrigeration cycle 21 is set. The target value Tr2m of the supercooling refrigerant temperature (target value of the supercooling degree) is corrected (ST105). The operation request level is an index indicating the necessity of operation of the supercooling refrigeration cycle 21. When the cooling capacity is excessive with respect to the cooling load, there is no need to operate the supercooling refrigeration cycle 21, Indicates that the operation request level is low. When the supercooling request level is small, the target value of the supercooling degree is increased and the cooling capacity is reduced, so that energy loss due to ON / OFF of the refrigeration cycle 20 for refrigeration or refrigeration is reduced, and the warehouse to be cooled is stored. The internal temperature is stable. The required operation level is determined by the cooling load based on, for example, the operating rate of the refrigeration or refrigeration compressor 1, the outdoor air temperature measured by the refrigeration or freezing outdoor air temperature detection means 42, or the subcooling outdoor air temperature detection means 43. Guess and decide. The operation request level may be changed step by step or may be changed linearly (linearly).

  Also, in the refrigeration or refrigeration cycle 20, when the piping from the outlet of the supercooling heat exchanger 12 to the inlet of the refrigeration or refrigeration throttle means 5a, 5b is not insulated from the surrounding air or is not sufficiently insulated When the supercooled refrigerant temperature Tr2 becomes 0 ° C. or lower, the pipe freezes. If the surface of the pipe freezes, the heat transfer area of the pipe increases, resulting in an increase in heat loss and a decrease in performance. Further, when ice melts, water falls into the machine room and the room, causing problems in equipment reliability. For this reason, by setting the target value Tr2m of the supercooling refrigerant temperature to 0 ° C. or higher and preventing the pipe from freezing, it is possible to construct a highly reliable system by preventing performance degradation due to heat loss of the pipe after supercooling. Of course, by disposing the supercooling heat exchanger 12 as close as possible to the refrigeration or refrigeration squeezing means 5a, 5b, it is possible to minimize heat loss in the pipe after supercooling.

  Next, when the refrigerant is supercooled, the cooling capacity in the refrigeration or freezing indoor heat exchangers 6a and 6b increases, but the cooling load does not change. 1 will be turned ON / OFF, and the efficiency will deteriorate. Therefore, the target low pressure Psrm, which is the control target of the refrigeration or refrigeration compressor 1, is changed according to the degree of supercooling (ST106). For example, the degree of supercooling is 5 ° C. or lower, 5 to 10 ° C., 10 to 15 ° C., 15 ° C. or higher, and the target low pressure Psrm is changed. By doing so, the refrigeration capacity is increased and ON / OFF of the compressor 1 is prevented from being increased, and the low-pressure control target is increased, so that the frequency of the compressor 1 is also lowered, and the efficiency is high and the energy is low. Driving becomes possible. Note that the target low pressure Psrm may be changed stepwise, or the amount of increase in the low pressure control target value may be calculated directly from the degree of supercooling.

  Note that the degree of supercooling of the refrigeration or refrigeration cycle 20 depends on the condensation temperature calculated from the output of the refrigeration or refrigeration high pressure detection means 31 and the outlet of the heat exchanger 12 of the refrigeration or refrigeration cycle 20. It is obtained from the temperature difference from the supercooled refrigerant temperature, which is the temperature. Instead of calculating the condensing temperature by calculating the output of the refrigeration or refrigeration high pressure detection means 31, a temperature detection means (not shown) is provided in the piping of the refrigeration or refrigeration outdoor heat exchanger 2, and the condensation temperature is determined. It may be possible to detect directly.

  If the relationship between the low pressure and the compressor frequency and the heat exchange performance of the condenser are stored in advance, the degree of supercooling can be estimated to some extent although the accuracy is low, and the high pressure detection means 31 for refrigeration or freezing is used. Even if there is no, a similar system can be configured and the same effect can be obtained. The same can be said for the supercooling refrigeration cycle 21, and the same system can be configured without the high-pressure detecting means 33, and the same effect can be obtained.

  The means for detecting the evaporating temperature of the refrigeration or refrigeration cycle 20 (first evaporating temperature detecting means) is calculated from the refrigeration or refrigeration low-pressure pressure detecting means 32. Alternatively, temperature detecting means (not shown) may be attached to the piping of the freezing indoor heat exchangers 6a and 6b so that the evaporation temperature can be detected directly.

  FIG. 4 shows a control operation performed by the supercooling control device 52. The control target value Tr2m (or the target value of the degree of supercooling) of the supercooling refrigerant temperature calculated in the refrigeration or refrigeration cycle control flowchart is read (ST201). This value is passed from the control device for refrigeration or freezing via the communication line 53. The operating capacity of the supercooling compressor 8 is controlled so that the supercooling refrigerant temperature Tr2 approaches the control target value Tr2m (or the supercooling degree target value) (ST202). This supercooling refrigerant temperature Tr2 is obtained from the output of the supercooling low-pressure pressure detecting means 34 of the supercooling refrigeration cycle 21 or the evaporation temperature of the supercooling refrigeration cycle 21 as described above.

  The supercooling throttling means 11 controls the amount of throttling so that the degree of superheat is generated on the outlet side of the supercooling refrigeration cycle of the supercooling heat exchanger 12 (ST203). The degree of superheat at the outlet of the supercooling heat exchanger 12 is determined by calculating the evaporation temperature calculated from the low-pressure pressure detecting means 34 of the supercooling compressor 8 and the temperature measured by the supercooling heat exchanger outlet temperature detecting means 44. It is obtained from the temperature difference.

  By controlling the degree of superheat to an appropriate value, for example, 3 ° C., the refrigerant is surely evaporated before the supercooling compressor 8 and the reliability of the compressor 8 can be ensured. In addition, since the refrigerant has two phases over the entire area of the supercooling heat exchanger 12, the heat exchange efficiency is improved and the COP is improved.

  In order to control the degree of superheat, a discharge temperature detection means (not shown) is provided in a pipe from the supercooling compressor 8 to the inlet of the supercooling outdoor heat exchanger 9, and the supercooling refrigeration cycle 21 From the high pressure, the low pressure and the slope of the compression process on the ph diagram of FIG. 2, a target value of the discharge temperature of the compressor 8 that makes the superheat degree appropriate is calculated, and the discharge temperature detecting means The degree of opening of the subcooling throttle means 11 may be adjusted so that the measured value of the value approaches the target value.

  The means for detecting the evaporating temperature of the subcooling refrigeration cycle 21 (second evaporating temperature detecting means) is calculated from the subcooling low pressure pressure detecting means 34, but the subcooling heat exchanger The temperature detection means may be provided in the 12 pipes so that the evaporation temperature can be detected directly.

  Note that the control flowcharts of FIGS. 3 and 4 have the advantage that a general-purpose system can be configured if they are stored on different substrates, but similar operations are possible even if they are stored on a single substrate. Needless to say, in this case, communication between the boards is unnecessary, and the system becomes simpler and faster in response. Also, if you have another board, the communication items listed here are the items that are necessary to operate at the minimum, not limited to this, it is more advanced and more stable to perform more communication Increased energy saving system can be constructed. Further, communication between the substrates may be performed by contact, serial communication, or any other method.

  Further, in the present embodiment, the case where signals are exchanged via the communication line 53 between the control device 51 for the refrigeration or refrigeration cycle and the control device 52 for the supercooling refrigeration cycle will be described as an example. Although the refrigeration apparatus does not have a connection port for the communication line 53 and cannot exchange signals, for example, the target value of the evaporation temperature of the subcooling refrigeration cycle 21 is fixed at, for example, 0 ° C. By providing a low-pressure cut value and stopping the supercooling device, the energy-saving performance is somewhat deteriorated, but an energy-saving system can be constructed.

  In the present embodiment, the case where the present invention is applied to a refrigeration cycle and a refrigeration cycle that cools the interior to a predetermined temperature has been described. However, the present invention is not limited to this, and other components such as an air conditioner can be used. The present invention can also be applied to other refrigeration apparatuses. When applied to refrigeration and refrigeration cycles, the evaporation temperature is low (eg, -10 ° C), so when combined with a supercooling refrigeration cycle capable of operating at a high evaporation temperature, the system as a whole There is an effect that energy saving effect becomes higher.

In FIG. 2, for ease of explanation, the case where the refrigerant in the refrigeration or refrigeration cycle and the refrigerant in the supercooling refrigeration cycle are the same refrigerant is described as an example. However, different refrigerants suitable for each temperature zone can be used, and the same energy saving effect can be obtained. As the refrigerant, fluorocarbon refrigerants such as R410A, R407C, and R404A, natural refrigerants such as CO ₂ and propane, and other refrigerants can be used, but these are not limited to these, and any combination of refrigerants may be used. . Moreover, since each refrigerating cycle is independent, refrigerating machine oil can use the refrigerating machine oil suitable for each refrigerating cycle, and it does not matter if it uses each different refrigerating machine oil.

  In the above description, the supercooled refrigerant temperature detecting means (refrigerant temperature detecting means) 41 has been described as being not installed. However, if it is not a remote condenser type refrigeration apparatus, the supercooled refrigerant temperature is not limited. Since there is no restriction that the detection means 41 must be wired between the machine room and the outside, in such a case, the supercooled refrigerant temperature detection means 41 may be installed. The supercooling refrigerant temperature at the outlet of the supercooling heat exchanger 12 of the refrigeration or freezing refrigeration cycle 20 can be detected from the output, and the supercooling low pressure pressure detecting means 34 of the supercooling refrigeration cycle 21 as described above. Need to be obtained from the output of the above or the evaporation temperature of the subcooling refrigeration cycle 21. In such a case, the control device 52 functions as the control means of the present invention in addition to the second control means of the present invention. When the supercooling refrigerant temperature detecting means 41 is installed, the supercooling refrigerant temperature detection means 41 from the outlet side of the supercooling heat exchanger 12 of the refrigeration or refrigeration cycle 20 to the inlet of the refrigeration or refrigeration throttle means 5a, 5b. The cooling refrigerant temperature is detected with high accuracy, and the control device 52 controls the supercooling refrigeration cycle 21 so that the detected supercooling refrigerant temperature becomes the target value of the supercooling refrigerant temperature. A refrigeration system that can perform stable control and save energy can be obtained. The temperature detecting means 41 is in contact with the refrigerant pipe or inserted into the refrigerant pipe in the same manner as the temperature detecting means 44.

Embodiment 2. FIG.
Next, the second embodiment will be described with reference to the drawings. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

  FIG. 5 is a refrigerant circuit diagram of the refrigeration system showing the second embodiment. As shown in FIG. 5, this refrigeration system is a configuration example in the case of a remote condenser type refrigeration apparatus in which a compressor 1 and a liquid receiver 4 of a refrigeration or refrigeration cycle are installed in a machine room A or the like. It is. The refrigeration or freezing indoor heat exchangers 6a and 6b are installed indoors, and the refrigeration or freezing expansion means 5a and 5b are installed between the machine room and the indoors. In FIG. 5, the subcooling outdoor heat exchanger outlet temperature detection means 45 for measuring the outlet temperature of the subcooling outdoor heat exchanger 9 is provided.

  In this case, the subcooling refrigeration cycle 21 acts to supercool the refrigeration or refrigeration refrigeration cycle 20, so that the flow path between the liquid receiver 4 and the refrigeration or refrigeration throttling means 5a, 5b. It is necessary to install the supercooling heat exchanger 12 in the machine room A at the outlet of the liquid receiver 4 because it is complicated in terms of construction to pull out the pipe to the outdoor side once. .

  When the supercooling heat exchanger 12 is located in the machine room A, the configuration as shown in FIG. 1 requires that the supercooling refrigerant temperature detecting means 41 be extended indoors and wired between the machine room and the outside. If it comprises as FIG. 5, the wiring between machine room-outdoors will become unnecessary, and construction will become easy. However, in this case, it is necessary to estimate the degree of supercooling of the refrigeration cycle 20 for refrigeration or refrigeration from the detection value of the detection means provided in the subcooling refrigeration cycle 21. The estimation method will be described below.

  The endothermic amount Qe [W] of the supercooling refrigeration cycle in the supercooling heat exchanger 12 can be expressed by the following equation (1).

[Equation 1]
Qe = Gre × (Hs−Hco) (1)

  Here, Gre is the mass flow rate [kg / s] of the supercooling refrigerant, the operating frequency of the supercooling compressor 8, the high pressure measured by the supercooling high pressure detector 33, and the supercooling pressure. It can be obtained from the relationship between the low pressure measured by the low pressure detector 34 and the compressor performance of the supercooling compressor 8 stored in the supercooling control device storage unit 63 in advance. Hs is the enthalpy [J / kg] of the compressor suction of the supercooling refrigeration cycle 21, and the low pressure measured by the supercooling low pressure detection means 34 and the supercooling heat exchanger outlet temperature detection means 44 It can be calculated from the measured temperature. Hco is the enthalpy [J / kg] at the outlet of the subcooling outdoor heat exchanger 9 and can be calculated from the temperature measured by the subcooling outdoor heat exchanger outlet temperature detecting means 45.

  On the other hand, the heat release amount Qr [W] of the refrigeration cycle 20 for refrigeration or freezing in the supercooling heat exchanger 12 can be expressed by the following equation (2).

[Equation 2]
Qr = Grr × (Hsci−Hsco) (2)

  Here, Grr is the mass flow rate [kg / s] of the refrigerant in the refrigeration or refrigeration cycle 20, and is determined by the operating frequency of the refrigeration or refrigeration compressor 1 and the refrigeration or refrigeration high-pressure detection means 31. The measured high pressure, the low pressure measured by the refrigeration or freezing low pressure detecting means 32, and the compression of the refrigeration or freezing compressor 1 stored in the refrigerating or freezing control device storage unit 61 in advance. It can be obtained from the relationship with machine performance. Hsci is the enthalpy [J / kg] at the inlet of the supercooling heat exchanger 12 of the refrigeration or refrigeration cycle 20, and is calculated from the high pressure measured by the refrigeration or refrigeration high pressure detection means 31. Since it is equal to the saturation enthalpy of the condensation temperature to be obtained, it can be obtained. Hsco is the enthalpy [J / kg] at the outlet of the supercooling heat exchanger 12 of the refrigeration or refrigeration cycle 20, and is a value determined by the temperature of the refrigerant after supercooling.

  In a steady state, the relationship of Qe = Qr is established, and therefore, when Hsco is solved from Equations (1) and (2), it can be expressed by Equation (3). Here, each value on the right side of the equation (3) is based on the measured value of the detecting means provided in the refrigeration or refrigeration cycle 20 and the measured value obtained by the detecting means provided in the subcooling refrigeration cycle 21. Since it is obtained by calculation, Hsco can be obtained.

[Equation 3]
Hsco = Hsci−Gre / Grr × (Hs−Hco) (3)

For example, in the case of the R404A refrigerant, the relationship between the enthalpy H [J / kg] of the liquid and the refrigerant temperature T (° C.) can be approximated by the equation (4). The refrigerant temperature Tr2 after supercooling is obtained.
T = 000697 × H-139.97 (4)

  As described above, the control device 52 has measured values of the detection means 31 and 32 provided in the refrigeration or freezing refrigeration cycle 20 (these measured values are taken from the control device 51 via the communication line 53), and The temperature of the supercooling refrigerant at the outlet of the supercooling heat exchanger 12 of the refrigeration or freezing refrigeration cycle 20 is estimated from the measured values of the detection means 33, 34, 44, 45 provided in the supercooling refrigeration cycle 21. Then, based on the temperature of the supercooling refrigerant, as in the case of the first embodiment, the supercooling compressor 8 is configured such that the refrigerant at the entrance of the refrigeration or freezing indoor heat exchangers 6a and 6b becomes two-phase. And the supercooling throttle means 11 are controlled so that the supercooling refrigerant temperature detecting means 41 in the first embodiment is wired between the machine room and the outside while maintaining the effects of the first embodiment. Ease of construction .

Embodiment 3 FIG.
Next, the third embodiment will be described with reference to the drawings. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 6 is a refrigerant circuit diagram of a refrigeration system showing Embodiment 3 of the present invention. In this refrigeration system, the subcooling outdoor heat exchanger 9 is installed close to the refrigeration or freezing outdoor heat exchanger 2, and the refrigeration or freezing outdoor fan 3 is refrigerated with the subcooling outdoor heat exchanger 9. At the same time, the air is fed into the outdoor heat exchanger 2 for freezing or freezing. The refrigeration or refrigeration control device (control means) 51 makes the refrigerant at the entrance of the refrigeration or refrigeration indoor heat exchangers 6a and 6b to be two-phase based on the temperature detected by the supercooled refrigerant temperature detection means 41. The supercooling compressor 8 and the supercooling throttle means 11 are controlled.

  The subcooling outdoor heat exchanger 9 and the refrigeration or freezing outdoor heat exchanger 2 do not share a heat transfer tube with each other, but if the heat exchanger is a plate fin tube, the fins are shared with each other. As a result, the heat exchange performance between the refrigerant pipes is further improved as compared with the proximity installation.

  With the configuration as described above, the refrigeration cycle system can be made compact, and the cooling power of the outdoor heat exchanger 9 for supercooling and the outdoor heat exchanger 2 for refrigeration or refrigeration is the refrigeration or refrigeration outdoor fan 3. Therefore, the power of the blower is reduced, and the efficiency of the system, that is, energy saving can be realized. The configurations of the subcooling outdoor heat exchanger 9 and the refrigeration or freezing outdoor heat exchanger 2 according to the third embodiment of the present invention are similarly applied to the first and second embodiments. In the third embodiment, similarly to the example of the second embodiment described above, the supercooling refrigerant temperature detection means 41 may be omitted and the supercooling refrigerant temperature may be calculated and obtained. In that case, as described above, wiring between the machine room and the outside becomes unnecessary, and the construction becomes easy.

1 is a refrigerant circuit diagram of a refrigeration system showing Embodiment 1 of the present invention. It is a ph diagram showing Embodiment 1 of the present invention. It is a control flowchart of the refrigerating cycle for refrigerating or freezing which shows Embodiment 1 of this invention. It is a control flowchart of the refrigerating cycle for supercooling which shows Embodiment 1 of this invention. It is a refrigerant circuit figure of the refrigerating system which shows Embodiment 2 of this invention. It is a refrigerant circuit figure of the refrigerating system which shows Embodiment 3 of this invention.

Explanation of symbols

1 Refrigeration or refrigeration compressor, 2 refrigeration or refrigeration outdoor heat exchanger, 3 refrigeration or refrigeration outdoor fan, 4 refrigeration or refrigeration receiver, 5a, 5b refrigeration or refrigeration throttle means, 6a, 6b Refrigeration or refrigeration indoor heat exchanger, 7a, 7b Refrigeration or refrigeration indoor blower, 8 Supercooling compressor, 9 Supercooling outdoor heat exchanger, 10 Supercooling outdoor blower, 11 Supercooling Throttle means, 12 Supercooling heat exchanger, 13 Refrigerant pipe, 14 Refrigerant pipe, 20 Refrigeration cycle for refrigeration or freezing, 21 Refrigeration cycle for supercooling, 31 High pressure detection means for refrigeration or freezing, 32 Or low pressure pressure detection means for freezing, 33 high pressure pressure detection means for supercooling, 34 low pressure pressure detection means for supercooling, 41 supercooling refrigerant temperature detection means, 42 outdoor air temperature detection means for refrigeration or freezing , 43 Supercooling outdoor air temperature detection means, 44 Supercooling heat exchanger outlet temperature detection means, 45 Supercooling outdoor heat exchanger outlet temperature detection means, 51 Control device for refrigeration or freezing, 52 Supercooling control Device, 53 communication line, 61 refrigeration and refrigeration control device storage unit, 62 refrigeration and refrigeration control device calculation unit, 63 supercooling control device storage unit, 64 supercooling control device calculation unit, A machine room.

Claims (10)

A first refrigeration cycle having a first compressor, a first heat exchanger, a first throttling means, and a second heat exchanger, and circulating a first refrigerant therein;
A second refrigeration cycle having a second compressor, a third heat exchanger, a second throttling means, and a fourth heat exchanger, and circulating a second refrigerant therein;
First low pressure detection means for detecting the pressure on the low pressure side of the first compressor of the first refrigeration cycle or first evaporation temperature detection means for detecting the evaporation temperature of the first refrigeration cycle;
First control means for controlling the operation of the first refrigeration cycle based on the detection value of the first low-pressure detection means or the first evaporation temperature detection means;
Second low pressure detection means for detecting the pressure on the low pressure side of the second compressor of the second refrigeration cycle or second evaporation temperature detection means for detecting the evaporation temperature of the second refrigeration cycle;
Second control means for controlling the operation of the second refrigeration cycle based on the detection value of the second low-pressure detection means or the second evaporation temperature detection means;
With
The fourth heat exchanger is a refrigerant-refrigerant heat exchanger that performs heat exchange between the refrigerant and the refrigerant, and the first throttling means from the outlet of the first heat exchanger of the first refrigeration cycle. Inserted in any position of the flow path to the inlet, configured so that the first refrigeration cycle and the second refrigeration cycle can exchange heat with each other,
Based on the operating state of the first refrigeration cycle, the first control means and the second control means are connected in a wired or wireless manner so as to control the operation of the second refrigeration cycle. Configured to be controllable,
The second control means is configured to detect the fourth heat exchanger of the first refrigeration cycle based on a detection value of the second low pressure detection means or the second evaporation temperature detection means of the second refrigeration cycle. Refrigerant temperature at any position in the flow path from the outlet side of the first throttle means or the saturation temperature of the two-phase refrigerant flowing in the first heat exchanger and the first refrigeration cycle A function of calculating a degree of supercooling that is a temperature difference from the refrigerant temperature at any position in the flow path from the outlet side of the fourth heat exchanger to the inlet of the first throttle means; An operation of the second refrigeration cycle is controlled based on the obtained refrigerant temperature or degree of supercooling.   2. The refrigeration system according to claim 1, wherein ON / OFF timing of the second compressor is controlled based on an ON / OFF state of the first compressor of the first refrigeration cycle.   The refrigeration system according to claim 2, wherein the second control means starts the second compressor with a delay relative to the first compressor.   2. The refrigeration system according to claim 1, wherein the low pressure control target value or the evaporation temperature control target value of the second refrigeration cycle is transmitted from the first control unit to the second control unit.   A control target value of the refrigerant temperature detection value or calculation value of the first refrigeration cycle or a two-phase refrigerant flowing in the first heat exchanger from the first control means to the second control means Is the temperature difference between the saturation temperature of the refrigerant and the refrigerant temperature at any position in the flow path from the outlet side of the fourth heat exchanger of the first refrigeration cycle to the inlet of the first throttle means The refrigeration system according to claim 2, wherein the control target value is transmitted. The refrigeration system according to any one of claims 1 to 5 , wherein the first heat exchanger and the third heat exchanger are arranged in a flow path of the same heat source. The refrigeration system according to any one of claims 1 to 6 , wherein the cooling capacity of the second refrigeration cycle is lower than the cooling capacity of the first refrigeration cycle. The refrigeration system according to any one of claims 1 to 7 , wherein the evaporating temperature or low pressure of the second refrigeration cycle is operated in a state higher than the evaporating temperature or low pressure of the first refrigeration cycle. .   The operation method of the refrigeration system according to claim 2 or 3, wherein the second refrigeration cycle is controlled so that the refrigerant at the inlet of the second heat exchanger has two phases.   The operation method of the refrigeration system according to any one of claims 1 to 9, wherein the refrigerant temperature is controlled to be 0 ° C or higher.

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