JP7171044B2 - refrigeration equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigeration system that temperature-controls a plurality of temperature-controlled objects by means of a plurality of evaporators provided in parallel.

Refrigerating systems are conventionally known that have a compressor, a condenser, an expansion valve, and one evaporator, and that have an evaporating pressure regulating valve between the evaporator and the compressor. An evaporating pressure regulating valve in such a refrigeration system is usually provided to prevent frosting of the evaporator. A refrigerating device such as a car air conditioner that is exposed to the outside air is usually provided with such an evaporating pressure regulating valve.

On the other hand, Patent Document 1 has a compressor, a condenser, and a plurality of sets of expansion valves and evaporators provided in parallel, and some of the evaporators and the compression A refrigeration system is disclosed in which an evaporating pressure regulating valve is provided between the compressor and another evaporator and no evaporating pressure regulating valve is provided between the other evaporator and the compressor.

The refrigeration system disclosed in Patent Document 1 is provided with an evaporating pressure regulating valve in order to control different temperatures for some evaporators and other evaporators. That is, in such a refrigeration system, the evaporating pressure of the refrigerant in some evaporators and the evaporating pressure of the refrigerant in the other evaporators can be made different from each other by adjusting the opening degree of the evaporating pressure regulating valve. Therefore, the refrigerating capacity of some evaporators can be made different from the refrigerating capacity of other evaporators.

A refrigeration system as disclosed in Patent Document 1 is useful in that it can cool a plurality of temperature-controlled objects to different temperatures using a plurality of evaporators while suppressing a footprint. Patent Document 1 discloses an example in which a plurality of evaporators are used to cool an indoor space in a convenience store or the like, a refrigerator, and a freezer at different temperatures. It can also be suitably applied to a manufacturing apparatus for precision parts having

When the refrigerating apparatus of Patent Document 1 is applied to a manufacturing apparatus for precision parts, etc., liquid may be cooled by a plurality of evaporators, and the temperature of a plurality of temperature control regions may be controlled by a plurality of liquids cooled to different temperatures. good. As an example of such a type of temperature control device (temperature control system), Patent Document 2 by the present applicant can be mentioned.

JP 2014-70835 A JP 2018-194240 A

In a refrigerating device or a temperature control device that is applied to a manufacturing apparatus or the like having a plurality of temperature control regions as described above, after controlling the temperature of some of the plurality of temperature control regions to a certain target temperature, the In some cases, it is required to implement a control pattern such as controlling the temperature of the same part at the target temperature. Also, it may be desired to implement a control pattern in which some of the temperature control regions need to be cooled while others need to be heated. Here, if it is necessary to heat the other portion, the refrigerating capacity of the evaporator corresponding to the other portion may be unnecessary or may be extremely small. In the latter control pattern, the temperature difference between the temperature of the refrigerant passing through the evaporator and the temperature of the object to be temperature-controlled by the evaporator can become large. Desired. Moreover, both the special control pattern and steady temperature control as described above are generally required to be performed with high accuracy.

However, the refrigeration apparatus of Patent Document 1 is intended for temperature control of indoor spaces, refrigerators, and freezers in convenience stores and the like, and is not intended to be applied to precision parts manufacturing sites and the like. Also, it does not require a strong degree of precision in temperature control. Therefore, Patent Literature 1 does not disclose knowledge that can meet the above-described demands that may occur in a precision component manufacturing apparatus or the like.

As a result of intensive research in consideration of the above-mentioned demands, the inventor of the present invention has found that by devising the operation of an evaporating pressure regulating valve, etc., in a refrigeration system equipped with a plurality of evaporators provided in parallel, it is possible to A control pattern in which a part is temperature-controlled at a certain target temperature and then the same part is temperature-controlled at a significantly different target temperature can be executed with high precision and stability. We have found a method that can easily reduce the load on the evaporator in the case of a control pattern in which one part needs to be cooled while another part needs to be heated.

According to the present invention, when a plurality of evaporators provided in parallel are used to temperature-control a plurality of temperature-controlled targets, even if the target temperature of some of the temperature-controlled targets is changed, highly accurate temperature control can be achieved. It can be performed stably and reduces the burden on the evaporator that can occur during control patterns where some temperature control areas need to be cooled while other temperature control areas need to be heated. An object of the present invention is to provide a refrigerating device that can be easily reduced.

A refrigeration system according to the present invention comprises a refrigeration circuit in which a compressor, a condenser, a first expansion valve, and a first evaporator are connected in this order so as to circulate the refrigerant; Refrigerant is branched from a portion downstream of the condenser and upstream of the first expansion valve, and passed through the second expansion valve, the second evaporator and the evaporation pressure regulating valve in this order, and the refrigeration refrigerant flowing between a parallel circuit returning to a portion of the circuit downstream of the first evaporator and upstream of the compressor, and between the second evaporator and the evaporative pressure regulator valve in the parallel circuit; a parallel side pressure sensor that detects pressure; and a control device that controls opening degrees of the first expansion valve, the second expansion valve, and the evaporating pressure adjustment valve, wherein the control device The first expansion valve and/or the second expansion valve are opened such that the flow rate of the refrigerant flowing out of the first expansion valve and the flow rate of the refrigerant flowing out of the second expansion valve are different values. When the temperature is controlled, if the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is smaller than a predetermined value and controlling the opening degree of the evaporating pressure regulating valve so that the pressure of the refrigerant detected by the parallel side pressure sensor matches the evaporating pressure of the refrigerant in the first evaporator, and the first expansion valve When the opening degree of the first expansion valve and/or the second expansion valve is controlled such that the flow rate of the refrigerant flowing out and the flow rate of the refrigerant flowing out from the second expansion valve are different values. When the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the object to be temperature controlled before heat exchange with the refrigerant in the second evaporator is equal to or greater than the predetermined value, the second The degree of opening of the evaporating pressure regulating valve is adjusted so that the difference between the evaporation temperature of the refrigerant in the evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator becomes smaller than the predetermined value. The degree of opening of the first expansion valve and/or the second expansion valve is made smaller than before the control.

In the present invention, for example, it is necessary to greatly change the target temperature of the temperature controlled object temperature controlled by the first evaporator to the low temperature side from a certain point, and the temperature controlled object temperature controlled by the second evaporator is large. The refrigerating capacity of the first evaporator is increased by making the flow rate of the refrigerant flowing out of the first expansion valve greater than the flow rate of the refrigerant flowing out of the second expansion valve when the capacity is not required. The direction can be changed, and the direction can be changed to decrease the refrigerating capacity of the second expansion valve. However, at this time, since the pressure of the refrigerant flowing out from the second evaporator side can be lower than the evaporation pressure of the refrigerant in the first evaporator, the refrigerant from the second evaporator side is When it joins with the refrigerant from the side, the state of the refrigerant may be disturbed, which may impair the stability of the operation of the refrigeration system. Here, in the present invention, when the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is smaller than a predetermined value, the second The evaporating pressure control valve adjusts the degree of opening so that the evaporating pressure of the refrigerant flowing out from the second evaporator side matches the evaporating pressure of the refrigerant in the first evaporator. This stabilizes the state of the refrigerant when the refrigerant flowing out from the first evaporator side and the refrigerant flowing out from the second evaporator side join together.
Further, for example, when it is necessary to cool the temperature-controlled target whose temperature is controlled by the first evaporator and it is necessary to heat the temperature-controlled target whose temperature is controlled by the second evaporator, the first expansion By making the flow rate of the refrigerant flowing out of the valve larger than the flow rate of the refrigerant flowing out of the second expansion valve, the refrigerating capacity of the first evaporator can be changed to increase, and the refrigerating capacity of the second expansion valve can be increased. Can be changed in the direction of decreasing ability. However, at this time, if the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the object to be temperature-controlled before heat exchange by the second evaporator is excessively large, the second evaporator It is burdensome and can pose a risk of injury. Here, in the present invention, when the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is a predetermined value or more, the temperature difference It is determined that it is at the warning level, and the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator evaporates so that it becomes smaller than a predetermined value. The degree of opening of the pressure regulating valve is made smaller than the state before the degree of opening of the first expansion valve and/or the second expansion valve is controlled. As a result, the evaporation temperature of the refrigerant in the second evaporator is raised to suppress the temperature difference between the refrigerant in the second evaporator and the temperature controlled target, thereby reducing the load on the second evaporator.
Therefore, when temperature-controlling multiple temperature-controlled targets with multiple evaporators installed in parallel, high-precision temperature control can be stably performed even when the target temperature of some of the temperature-controlled targets is changed. and the evaporator (heating side evaporation It is possible to easily reduce the burden on the equipment).

The parallel circuit further includes a third expansion valve and a third evaporator provided in parallel with the second expansion valve and the second evaporator, and the condensation in the refrigeration circuit is Refrigerant branching from a portion downstream of the vessel and upstream of the first expansion valve is passed through the third expansion valve and the third evaporator in that order, and flows out of the second evaporator. After joining with the refrigerant, it is returned to the refrigeration circuit, the control device also controls the opening of the third expansion valve, and the control device controls the flow out of the first expansion valve. The first expansion valve, the second expansion valve and the When the opening degree of at least one of the third expansion valves is controlled, the evaporation temperature of the refrigerant in the second evaporator and the temperature control target before heat exchange with the refrigerant in the second evaporator and the difference between the evaporation temperature of the refrigerant in the third evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the third evaporator is smaller than the predetermined value. controls the opening degree of the evaporating pressure regulating valve so that the pressure of the refrigerant detected by the parallel side pressure sensor matches the evaporating pressure of the refrigerant in the first evaporator, and the first expansion valve The first expansion valve and the second expansion valve are arranged such that the flow rate of the refrigerant flowing out from the second expansion valve and/or the flow rate of the refrigerant flowing out from the third expansion valve are different values. Evaporation temperature of the refrigerant in the second evaporator and temperature control before heat exchange with the refrigerant in the second evaporator when the opening degree of at least one of the valve and the third expansion valve is controlled At least one of the difference from the target temperature and the difference between the evaporation temperature of the refrigerant in the third evaporator and the temperature of the temperature control target before heat exchange with the refrigerant in the third evaporator If it is equal to or greater than the predetermined value, the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator and the third evaporator The opening degree of the evaporating pressure regulating valve is set so that the difference between the evaporation temperature of the refrigerant in the third evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the third evaporator becomes smaller than the predetermined value. The degree of opening of at least one of the first expansion valve, the second expansion valve, and the third expansion valve may be smaller than before the control.

In this case, one evaporating pressure control valve is shared by the second evaporator and the third evaporator, thereby simplifying the circuit configuration and precisely controlling the temperature by the first to third evaporators. And it can be performed stably.

Further, the parallel side pressure sensor may detect the pressure of the refrigerant at a confluence portion of the refrigerant flowing out of the second evaporator and the refrigerant flowing out of the third evaporator or downstream of the confluence portion. .

In this case also, the pressure of the refrigerant on the downstream side of the second evaporator and the third evaporator can be controlled to a desired value with one parallel side pressure sensor, so the circuit configuration can be simplified.

Further, in the refrigerating apparatus according to the present invention, the refrigerating circuit side pressure detector detects the pressure of refrigerant flowing in a portion downstream of the first evaporator in the refrigerating circuit and upstream of a connection position of the parallel circuit. A sensor may be further provided, and the evaporating pressure of the refrigerant in the first evaporator may be specified by the refrigerating circuit side pressure sensor.

In this case, the target control value for the refrigerant pressure detected by the parallel-side pressure sensor, that is, the refrigerant evaporation pressure in the first evaporator can be accurately set.

Another refrigeration system according to the present invention includes a refrigeration circuit in which a compressor, a condenser, a first expansion valve, and a first evaporator are connected in this order so as to circulate the refrigerant, Refrigerant is branched from a portion of the refrigeration circuit downstream of the condenser and upstream of the first expansion valve, and passed through the second expansion valve, the second evaporator and the evaporation pressure regulating valve in that order. a parallel circuit returning to a portion downstream of the first evaporator and upstream of the compressor in the refrigeration circuit; When the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is equal to or greater than a predetermined value, the second The degree of opening of the evaporating pressure regulating valve is controlled so that the difference between the evaporating temperature of the refrigerant in the evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator becomes smaller than the predetermined value. do.

According to the present invention, when temperature-controlling a plurality of temperature-controlled targets with a plurality of evaporators provided in parallel, high-accuracy temperature control can be achieved even when the target temperatures of some of the temperature-controlled targets are changed. While the control can be performed stably, the evaporator that can occur during a control pattern in which some temperature control areas need to be cooled while other temperature control areas need to be heated You can easily reduce the burden.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the temperature control system provided with the refrigerating device which concerns on one embodiment of this invention. FIG. 2 is a diagram showing a flowchart for explaining an example of the operation of the refrigeration system shown in FIG. 1;

An embodiment of the present invention will be described below.

FIG. 1 is a diagram showing a schematic configuration of a temperature control system S including a refrigerating apparatus 1 according to one embodiment of the present invention. As shown in FIG. 1, the temperature control system S according to the present embodiment includes a refrigerating device 1, a fluid circulation unit 2 for circulating a fluid whose temperature is controlled by the refrigerating device 1, and a control device 50. I have. The temperature controlled fluid may be a liquid or a gas. The refrigerating apparatus 1 includes a refrigerating circuit 10, a parallel circuit 20, a refrigerating circuit side pressure sensor 30, a parallel side pressure sensor 40, a parallel side first temperature sensor 61, and a parallel side second temperature sensor 62. there is The fluid circulation unit 2 includes a first fluid circulation device 2A for circulating the first fluid, a second fluid circulation device 2B for circulating the second fluid, and a second fluid circulation device 2B for circulating the third fluid. and a three-fluid flow device 2C.

<Freezer>
First, the refrigerator 1 will be described. A refrigerating circuit 10 of the refrigerating apparatus 1 includes a compressor 11, a condenser 12, a first expansion valve 13, and a first evaporator 14, which are connected by piping so as to circulate the refrigerant in this order. is.

In the refrigeration circuit 10, the refrigerant compressed by the compressor 11 flows into the condenser 12, and the refrigerant flowing into the condenser 12 is condensed by air cooling or liquid cooling. After that, the refrigerant is decompressed by the first expansion valve 13 to be in a low-temperature gas-liquid mixed state, and flows into the first evaporator 14 . The refrigerant that has flowed into the first evaporator 14 exchanges heat with a temperature controlled object (the first fluid in this example), flows into the compressor 11, and is then compressed again by the compressor 11. .

The first expansion valve 13 is an electronic expansion valve whose opening can be adjusted by a control signal such as a pulse signal. The first expansion valve 13 is electrically connected to the control device 50 and adjusts the degree of opening according to the control signal output by the control device 50 .

The parallel circuit 20 branches the refrigerant from a portion of the refrigeration circuit 10 downstream of the condenser 12 and upstream of the first expansion valve 13, and connects the second expansion valve 21, the second evaporator 22, and the evaporating pressure It is configured to pass through the regulating valve 23 in order and return to the downstream side of the first evaporator 14 and the upstream side of the compressor 11 in the refrigeration circuit 10 .

The parallel circuit 20 in the present embodiment further includes a third expansion valve 24 and a third evaporator 25 provided in parallel with the second expansion valve 21 and the second evaporator 22. is doing. The parallel circuit 20 also allows the refrigerant branched from the refrigerating circuit 10 to pass through the third expansion valve 24 and the third evaporator 25 in that order and return to the refrigerating circuit 10 . The second expansion valve 21 decompresses the refrigerant into a low-temperature gas-liquid mixed state, and sends the refrigerant to the second evaporator 22 . The third expansion valve 24 decompresses the refrigerant into a low-temperature gas-liquid mixed state, and sends the refrigerant to the third evaporator 25 . As a result, in the refrigerating apparatus 1, the second evaporator 22 and the third evaporator 25 control the temperature of a temperature controlled object other than the temperature controlled object of the first evaporator 14 (in this example, the second fluid and third fluid) can be temperature controlled. The second evaporator 22 and the third evaporator 25 may temperature-control the same temperature-controlled object, or may temperature-control different temperature-controlled objects.

Further, in the present embodiment, the refrigerant flowing out from the second evaporator 22 and the refrigerant flowing out from the third evaporator 25 join on the upstream side of the evaporating pressure regulating valve 23 . The merged refrigerant flows into the compressor 11 through the evaporating pressure regulating valve 23 .

The refrigerant flowing out of the third evaporator 25 may flow into the downstream side of the evaporating pressure regulating valve 23. It is preferable to provide an evaporation pressure regulating valve separate from the pressure regulating valve 23 . Moreover, although the third expansion valve 24 and the third evaporator 25 are provided in the present embodiment, these may be omitted. A set of an expansion valve and an evaporator is further provided in parallel with the second expansion valve 21 and the second evaporator 22, and the third expansion valve 24 and the third evaporator 25. I don't mind.

The second expansion valve 21 and the third expansion valve 24 are electronic expansion valves, and their opening degrees can be adjusted by control signals such as pulse signals. The second expansion valve 21 and the third expansion valve 24 are electrically connected to the control device 50 and adjust their opening according to the control signal output by the control device 50 .

The evaporating pressure adjusting valve 23 is also an electronic expansion valve, and like the first evaporator 14, the opening can be adjusted by a control signal such as a pulse signal. The evaporating pressure regulating valve 23 is electrically connected to the control device 50 and adjusts the degree of opening according to the control signal output by the control device 50 . Evaporation pressure adjustment valve 23 is provided to adjust the pressure of the refrigerant flowing out from second evaporator 22 and third evaporator 25 and joining together to a desired value.

On the other hand, the refrigeration circuit side pressure sensor 30 is provided to detect the pressure of the refrigerant flowing in the portion downstream of the first evaporator 14 in the refrigeration circuit 10 and upstream of the connection position of the parallel circuit 20 . It is More specifically, the refrigeration circuit side pressure sensor 30 is provided to identify the refrigerant evaporation pressure (P1) in the first evaporator 14 .

The parallel side pressure sensor 40 detects the pressure of refrigerant flowing between the second evaporator 22 and the evaporation pressure regulating valve 23 in the parallel circuit 20 . More specifically, the parallel side pressure sensor 40 in the present embodiment detects the confluence of the refrigerant flowing out of the second evaporator 22 and the refrigerant flowing out of the third evaporator 25 or the downstream side of the confluence. By detecting the pressure, the pressure of the refrigerant that flows out from the second evaporator 22 and the third evaporator 25 and merges is detected.

The parallel-side first temperature sensor 61 detects the evaporation temperature of the gas-liquid mixed refrigerant expanded by the second expansion valve 21, that is, the evaporation temperature of the refrigerant in the second evaporator 22. there is The parallel-side second temperature sensor 62 detects the evaporation temperature of the gas-liquid mixed refrigerant expanded by the third expansion valve 24, that is, the evaporation temperature of the refrigerant in the third evaporator 25. there is

<Fluid circulation unit>
In the fluid circulation unit 2, the temperature of the first fluid circulated by the first fluid circulation device 2A is controlled by the first evaporator 14, and the second fluid circulated by the second fluid circulation device 2B is The temperature of the third fluid is controlled by the second evaporator 22 , and the temperature of the third fluid circulated by the third fluid flow device 2</b>C is controlled by the third evaporator 25 . The fluid communication unit 2 performs temperature control with each temperature-controlled fluid.

The first fluid circulation device 2A has a first pump 2A1 that generates driving force for causing the first fluid to flow.

The second fluid circulation device 2B includes a second pump 2B1 that generates a driving force for causing the second fluid to flow, and a second fluid temperature before heat exchange with the refrigerant in the second evaporator 22. and a second fluid temperature sensor 2B2 for detecting .

The third fluid circulation device 2C includes a third pump 2C1 that generates driving force for causing the third fluid to flow, and a third fluid temperature before heat exchange with the refrigerant in the third evaporator 25. and a third fluid temperature sensor 2C2 for detecting .

<Control device>
Subsequently, the control device 50 controls at least the opening degrees of the first expansion valve 13 , the second expansion valve 21 , the third expansion valve 24 and the evaporation pressure control valve 23 . Further, the control device 50 can acquire the refrigerant pressure detected by the refrigerating circuit-side pressure sensor 30 and the refrigerant pressure detected by the parallel-side pressure sensor 40 . In addition, the control device 50 detects the evaporation temperature of the refrigerant in the second evaporator 22 detected by the parallel-side first temperature sensor 61 and the refrigerant in the third evaporator 25 detected by the parallel-side second temperature sensor 62. and the evaporation temperature of Further, the control device 50 detects the temperature of the second fluid before heat exchange with the refrigerant in the second evaporator 22 detected by the second fluid temperature sensor 2B2, and the temperature of the second fluid detected by the third fluid temperature sensor 2C2. It is possible to acquire the detected temperature of the third fluid before heat exchange with the refrigerant in the third evaporator 25 .

The control device 50 adjusts the opening degrees of the first expansion valve 13, the second expansion valve 21 and the third expansion valve 24 in order to adjust the refrigerating capacity output by each evaporator (14, 22, 25). Adjust to increase or decrease the flow of refrigerant out of each valve. Further, when the flow rate of the refrigerant is adjusted in this way, the controller 50 interlocks and adjusts the opening degree of the evaporating pressure regulating valve 23 . The adjustment of the evaporating pressure regulating valve 23 is performed by adjusting the difference ( temperature difference ΔTx), and the difference (temperature difference ΔTy) is smaller than the predetermined value Th or is greater than or equal to the predetermined value Th. The predetermined value Th is the temperature difference between the refrigerant in the second evaporator 22 and the third evaporator 25 and the temperature control object to the extent that the second evaporator 22 and the third evaporator 25 are not overloaded. is set on the upper limit side of , and varies depending on the specifications (temperature difference resistance performance) of the second evaporator 22 and the third evaporator 25 . In the present embodiment, it is assumed that the temperature difference warning level is the case where the temperature difference between the refrigerant and the temperature controlled object in the second evaporator 22 and the third evaporator 25 is 90° C. or more, and the predetermined value Th is set to 80° C. as an example.

Specifically, the control of the control device 50 will be described. When the target temperature for the temperature controlled object whose temperature is controlled by the first evaporator 14, for example, is changed from the current value to a significantly lower temperature For example, the first expansion valve 13 and the second expansion valve 21 and/or the third expansion valve 24 have different values for the flow rate of the refrigerant flowing out from The degree of opening of at least one of the expansion valve 13, the second expansion valve 21 and the third expansion valve 24 can be controlled. Specifically, the flow rate of the refrigerant flowing out of the first expansion valve 13 is higher than the flow rate of refrigerant flowing out of the second expansion valve 21 and/or the third expansion valve 24. The degree of opening of at least one of the expansion valve 13, the second expansion valve 21 and the third expansion valve 24 can be controlled. In such control, for example, by making the flow rate of refrigerant flowing out of the first expansion valve 13 larger than the flow rate of refrigerant flowing out of each of the second expansion valve 21 and the third expansion valve 24, A part of the refrigerating capacity of the second evaporator 22 and the third evaporator 25 is added to the refrigerating capacity of the first evaporator 14 to increase the refrigerating capacity output by the first evaporator 14 and change It is possible to immediately respond to the target temperature.

When the above-described control is performed, the temperature of the temperature controlled object (second fluid) before heat exchange with the refrigerant in the second evaporator 22 and the temperature of the refrigerant in the second evaporator 22 The difference (temperature difference ΔTx), and the difference between the evaporation temperature of the refrigerant in the third evaporator 25 and the temperature of the temperature controlled object (third fluid) before heat exchange with the refrigerant in the third evaporator 25 ( When the temperature difference ΔTy) is smaller than the predetermined value Th, the control device 50 controls the pressure of the refrigerant detected by the parallel side pressure sensor 40 to match the evaporation pressure of the refrigerant in the first evaporator 14. The opening degree of the evaporation pressure control valve 23 is controlled. At this time, the evaporating pressure of the refrigerant in the first evaporator 14 is acquired from the refrigerating circuit side pressure sensor 30 .
More specifically, when the flow rate of refrigerant flowing out of the first expansion valve 13 is made larger than the flow rate of refrigerant flowing out of each of the second expansion valve 21 and the third expansion valve 24, As the flow rate of the refrigerant flowing out of each of the second expansion valve 21 and the third expansion valve 24 decreases, the pressure of the refrigerant flowing out of the corresponding second evaporator 22 and third evaporator 25 (evaporation A situation may arise where the pressure) is lower than the evaporating pressure of the refrigerant in the first evaporator 14 . At this time, by making the degree of opening of the evaporating pressure regulating valve 23 smaller than the state before controlling the degree of opening of the expansion valves (13, 21, 24) (before controlling the flow rate), the parallel side pressure sensor 40 The pressure of the refrigerant detected by is made to match the evaporation pressure of the refrigerant in the first evaporator 14 . This stabilizes the operation of the refrigeration system 1 as described later.

On the other hand, when the flow rate of refrigerant flowing out of the first expansion valve 13 is made larger than the flow rate of refrigerant flowing out of each of the second expansion valve 21 and the third expansion valve 24, the second evaporator 22 and the difference (temperature difference ΔTx) between the evaporation temperature of the refrigerant in the second evaporator 22 and the temperature of the temperature controlled object (second fluid) before heat exchange with the refrigerant in the second evaporator 22, and the third evaporator 25 At least one of the difference (temperature difference ΔTy) between the evaporation temperature of the refrigerant and the temperature of the temperature controlled object (third fluid) before heat exchange with the refrigerant in the third evaporator 25 is equal to or greater than a predetermined value Th. In some cases, the control device 50 detects the difference between the evaporation temperature of the refrigerant in the second evaporator 22 and the temperature of the temperature controlled object (second fluid) before heat exchange with the refrigerant in the second evaporator 22. (temperature difference ΔTx) and the difference (temperature difference ΔTy ) is smaller than the predetermined value Th, the opening degree of the evaporating pressure regulating valve 23 is made smaller than the state before controlling the opening degree of the expansion valves (13, 21, 24) (before the flow rate control). When the opening degree of the evaporating pressure regulating valve 23 is reduced, the evaporation temperature of the refrigerant rises, so the temperature difference between the refrigerant and the temperature controlled object in the second evaporator 22 and/or the third evaporator 25 is suppressed. It is possible to reduce the load on the second evaporator 22 and/or the third evaporator 25 .
Note that the control device 50 may be configured by a computer including a CPU, ROM, RAM, etc., and may control the operation of each section according to a stored program.

Next, an example of the operation of the refrigeration system 1 will be described with reference to the flowchart shown in FIG.

The process shown in FIG. 2 starts when the flow rate is controlled by controlling the degree of opening of the expansion valves (13, 21, 24).

When the process starts, first in step S1, the control device 50 determines the temperature between the evaporation temperature of the refrigerant in the second evaporator 22 and the temperature of the second fluid before heat exchange with the refrigerant in the second evaporator 22. At least one of the difference ΔTx and the temperature difference ΔTy between the evaporation temperature of the refrigerant in the third evaporator 25 and the temperature of the third fluid before heat exchange with the refrigerant in the third evaporator 25 is predetermined. It detects whether or not it is greater than or equal to the value Th. When both the temperature differences ΔTx and ΔTy are smaller than the predetermined value Th, the process proceeds to step S2, and when they are equal to or greater than the predetermined value Th, the process proceeds to step S6.

When the process proceeds to step S2, the control device 50 controls the pressure (P1) of the refrigerant flowing in the portion downstream of the first evaporator 14 in the refrigerating circuit 10 and upstream of the connection position of the parallel circuit 20. is acquired from the refrigerating circuit side pressure sensor 30 . The pressure (P1) detected here is treated as the evaporation pressure of the refrigerant in the first evaporator 14 . The control device 50 also obtains from the parallel side pressure sensor 40 the pressure (P2) of the refrigerant that flows out from the second evaporator 22 and the third evaporator 25 and merges. Then, the control device 50 determines whether or not the pressure (P1) and the pressure (P2) match, and if they match, returns to the process of monitoring the temperature difference (S1). If they do not match, the process proceeds to step S3.

In step S3, control device 50 determines whether pressure (P1) is greater than pressure (P2). When the pressure (P1) is higher than the pressure (P2), the evaporation pressure of the refrigerant in the first evaporator 14 is equal to the evaporation pressure of the refrigerant flowing out of the second evaporator 22 and the third evaporator 25 and joining together. Means greater than pressure. In this case, in step S4, the control device 50 reduces the opening degree of the evaporating pressure regulating valve 23 (DOWN), and evaporates the refrigerant flowing out and joining the second evaporator 22 and the third evaporator 25. Increase pressure. Then, the control device 50 returns to the process of monitoring the temperature difference (S1). The degree of opening of the pressure regulating valve 23 is adjusted.

On the other hand, if the pressure (P1) is less than the pressure (P2), this condition is such that the evaporating pressure of the refrigerant in the first evaporator 14 flows out of the second evaporator 22 and the third evaporator 25. It means that the evaporation pressure is lower than the evaporating pressure of the refrigerant that joins together. In this case, in step S5, the control device 50 increases the opening degree of the evaporating pressure regulating valve 23 (UP), and evaporates the refrigerant that flows out from the second evaporator 22 and the third evaporator 25 and merges. Reduce pressure. Then, when the temperature difference ΔTx and the temperature difference ΔTy are smaller than the predetermined value Th, the controller 50 adjusts the opening degree of the evaporating pressure regulating valve 23 until the pressure (P1) matches the pressure (P2).

When the refrigerant pressure (P2) detected by the parallel side pressure sensor 40 matches the refrigerant evaporation pressure (P1) in the first evaporator 14 by adjusting the opening degree of the evaporation pressure regulating valve 23 as described above, can suppress the state of the refrigerant from being disturbed when the refrigerant flowing out from the first evaporator 14 side and the refrigerant flowing out from the second evaporator 22 and the third evaporator 25 side merge, As a result, the operation of the refrigeration system 1 is stabilized.

On the other hand, in step S1, when at least one of the temperature difference ΔTx and the temperature difference ΔTy is equal to or greater than the predetermined value Th, the temperature difference ΔTx and/or the temperature difference ΔTy is the second evaporator 22 and/or the third evaporator. It is determined that the load applied to the device 25 is large. At this time, the control device 50 reduces the opening degree of the evaporating pressure regulating valve 23 so that the temperature difference ΔTx and the temperature difference ΔTy become smaller than the predetermined value Th (DOWN), and the second evaporator 22 and the third increases the evaporation temperature of the refrigerant in the evaporator 25 of . This makes it possible to suppress the temperature difference ΔTx and the temperature difference ΔTy.

In the refrigerating apparatus 1 according to the present embodiment described above, for example, it is necessary to greatly change the target temperature of the temperature controlled object (first fluid) whose temperature is controlled by the first evaporator 14 from a certain point to the low temperature side. , and the first expansion By making the flow rate of the refrigerant flowing out of the valve 13 larger than the flow rate of the refrigerant flowing out of the second expansion valve 21 and the third expansion valve 24, the refrigerating capacity of the first evaporator 14 is changed to increase. In addition, the refrigerating capacity of the second expansion valve 21 and the third expansion valve 24 can be changed to decrease. However, at this time, since the pressure of the refrigerant flowing out from the second evaporator 22 and the third evaporator 25 may be lower than the refrigerant evaporation pressure in the first evaporator 14, the second evaporator 22 And when the refrigerant flowing out from the third evaporator 25 side joins with the refrigerant from the first evaporator 14 side, the state of the refrigerant may be disturbed, and the stability of the operation of the refrigeration system 1 may be impaired. . Here, in the refrigerating apparatus 1 according to the present embodiment, when the temperature difference ΔTx and the temperature difference ΔTy are smaller than the predetermined value Th, The evaporating pressure regulating valve 23 adjusts the degree of opening so that the pressure of the refrigerant thus obtained matches the evaporating pressure of the refrigerant in the first evaporator 14 . This stabilizes the state of the refrigerant when the refrigerant flowing out from the first evaporator 14 side and the refrigerant flowing out from the second evaporator 22 and the third evaporator 25 side join together.

In addition, for example, it is necessary to cool the temperature controlled object (first fluid) whose temperature is controlled by the first evaporator 14, and the temperature controlled by the second evaporator 22 and the third evaporator 25 When it is necessary to heat the object to be controlled (second fluid, third fluid), the flow rate of the refrigerant flowing out from the first expansion valve 13 is reduced from the second expansion valve 21 and the third expansion valve 24. By increasing the flow rate of the refrigerant, the refrigerating capacity of the first evaporator 14 can be changed to increase, and the refrigerating capacity of the second evaporator 22 and the third evaporator 25 can be decreased. can be changed. However, at this time, the temperature difference ΔTx between the evaporation temperature of the refrigerant in the second evaporator 22 and the temperature of the temperature controlled object (second fluid) before heat exchange by the second evaporator 22 and/or the second When the temperature difference ΔTy between the evaporation temperature of the refrigerant in the third evaporator 25 and the temperature of the temperature controlled object (third fluid) before heat exchange by the third evaporator 25 is excessively large, the second The first evaporator 22 and/or the third evaporator 25 may be strained and risk of damage.
Here, in the refrigerating apparatus 1 according to the present embodiment, when at least one of the temperature difference ΔTx and the temperature difference ΔTy is equal to or greater than the predetermined value Th, it is determined that the temperature difference alert level is reached, and the temperature difference ΔTx and at least one of the first expansion valve 13, the second expansion valve 21, and the third expansion valve 24 so that the temperature difference ΔTy becomes smaller than the predetermined value Th. The opening of the is made smaller than the state before controlling. As a result, the evaporation temperature of the refrigerant in the second evaporator 22 and the third evaporator 25 is raised, and the temperature difference ΔTx and the temperature difference ΔTy are suppressed, so that the second evaporator 22 and the third evaporator 25 can be reduced.

Therefore, when temperature-controlling a plurality of temperature-controlled targets with a plurality of evaporators (14, 22, 25) provided in parallel, even if the target temperatures of some of the temperature-controlled targets are changed, Accurate temperature control can be stably performed, and while some temperature control areas need to be cooled, other temperature control areas need to be heated. The load on the evaporator (heating-side evaporator) can be easily reduced.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described embodiment.

Reference Signs List 1 Refrigerating device 2 Fluid circulation unit 2A First fluid circulation device 2A1 First pump 2B Second fluid circulation device 2B1 Second pump 2B2 Second fluid temperature sensor 2C Third fluid Flow device 2C1 Third pump 2C2 Third fluid temperature sensor 10 Refrigerating circuit 11 Compressor 12 Condenser 13 First expansion valve 14 First evaporator 20 Parallel circuit 21 Second expansion valve 22 Second evaporator 23 Evaporation pressure regulating valve 24 Third expansion valve 25 Third evaporator 30 Refrigerating circuit side pressure sensor 40 Parallel side pressure sensor 50 Control device 61 Parallel side first temperature sensor 62... Parallel side second temperature sensor

Claims (4)

a refrigeration circuit in which the compressor, the condenser, the first expansion valve, and the first evaporator are connected in this order so as to circulate the refrigerant;
Refrigerant is branched from a portion of the refrigeration circuit downstream of the condenser and upstream of the first expansion valve, and passed through the second expansion valve, the second evaporator and the evaporation pressure regulating valve in that order. a parallel circuit returning to a portion of the refrigeration circuit downstream of the first evaporator and upstream of the compressor;
a parallel side pressure sensor that detects the pressure of the refrigerant flowing between the second evaporator and the evaporation pressure regulating valve in the parallel circuit;
a control device that controls opening degrees of the first expansion valve, the second expansion valve, and the evaporation pressure adjustment valve;
The control device is
the first expansion valve and/or the second expansion valve such that the flow rate of the refrigerant flowing out of the first expansion valve and the flow rate of the refrigerant flowing out of the second expansion valve are different values from each other; When the opening degree of is controlled, the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is smaller than a predetermined value controls the opening of the evaporating pressure regulating valve so that the pressure of the refrigerant detected by the parallel side pressure sensor matches the evaporating pressure of the refrigerant in the first evaporator;
the first expansion valve and/or the second expansion valve such that the flow rate of the refrigerant flowing out of the first expansion valve and the flow rate of the refrigerant flowing out of the second expansion valve are different values from each other; When the opening degree of is controlled, the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is the predetermined value or more The evaporating pressure is such that the difference between the evaporating temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator is smaller than the predetermined value A refrigeration system, wherein the degree of opening of a regulating valve is made smaller than the state before the degree of opening of the first expansion valve and/or the second expansion valve is controlled. The parallel circuit further includes a third expansion valve and a third evaporator provided in parallel with the second expansion valve and the second evaporator, Refrigerant branching from a portion downstream of the first expansion valve and upstream of the first expansion valve is passed through the third expansion valve and the third evaporator in that order, and the refrigerant flowing out of the second evaporator and After joining, it is also designed to return to the refrigeration circuit,
The control device also controls the degree of opening of the third expansion valve,
The control device is
the first expansion valve such that the flow rate of refrigerant flowing out of the first expansion valve and the flow rate of refrigerant flowing out of the second expansion valve and/or the third expansion valve are different values from each other; , when the opening degree of at least one of the second expansion valve and the third expansion valve is controlled, the evaporation temperature of the refrigerant in the second evaporator and the refrigerant and heat in the second evaporator The difference between the temperature of the temperature controlled object before exchange and the difference between the evaporation temperature of the refrigerant in the third evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the third evaporator When it is smaller than the predetermined value, the opening degree of the evaporating pressure regulating valve is controlled so that the pressure of the refrigerant detected by the parallel side pressure sensor matches the evaporating pressure of the refrigerant in the first evaporator. death,
the first expansion valve such that the flow rate of refrigerant flowing out of the first expansion valve and the flow rate of refrigerant flowing out of the second expansion valve and/or the third expansion valve are different values from each other; , when the opening degree of at least one of the second expansion valve and the third expansion valve is controlled, the evaporation temperature of the refrigerant in the second evaporator and the refrigerant and heat in the second evaporator The difference between the temperature of the temperature controlled object before exchange and the difference between the evaporation temperature of the refrigerant in the third evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the third evaporator when at least one of them is equal to or greater than the predetermined value, the difference between the evaporation temperature of the refrigerant in the second evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the second evaporator; The evaporating pressure regulating valve is adjusted so that the difference between the evaporating temperature of the refrigerant in the third evaporator and the temperature of the temperature controlled object before heat exchange with the refrigerant in the third evaporator becomes smaller than the predetermined value. 2. The refrigeration system according to claim 1, wherein the degree of opening is made smaller than the state before controlling the degree of opening of at least one of the first expansion valve, the second expansion valve and the third expansion valve. Device. 3. The parallel side pressure sensor detects the pressure of the refrigerant at a confluence portion of the refrigerant flowing out of the second evaporator and the refrigerant flowing out of the third evaporator or downstream of the confluence portion. Refrigeration equipment as described. further comprising a refrigerating circuit-side pressure sensor that detects the pressure of refrigerant flowing in a portion downstream of the first evaporator in the refrigerating circuit and upstream of a connection position of the parallel circuit;
4. The refrigeration system according to any one of claims 1 to 3, wherein said refrigeration circuit side pressure sensor specifies the evaporation pressure of refrigerant in said first evaporator.

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