Refrigeration equipment and temperature control systems

Abstract

To stably obtain a desired refrigeration capacity, while suppressing increase in size, an energy consumption and an environmental load.SOLUTION: A refrigeration device 10 comprises a high temperature side refrigeration circuit 20 and a low temperature side refrigeration circuit 30. A water cooler 38 is provided between a compressor and a condenser in the low temperature side refrigeration circuit 30. The refrigeration device 10 is operated in such following relations that when a refrigeration capacity of an evaporator of the low temperature side refrigerating circuit 30 is defined as CL (Kw), a compression power of the compressor of the low temperature side refrigeration circuit 30 is defined as PA (Kw), a cooling capacity of the water cooler 38 is defined as CW (Kw), a refrigeration capacity of an evaporator of the high temperature side refrigerating circuit 20 is defined as CH (Kw), a refrigerant circulation amount in the high temperature side refrigeration circuit 20 is defined as F1 (Kg / hour), and a refrigerant circulation amount of the low temperature side refrigeration circuit 30 is defined as F2 (Kg / hour), 0.25×(CL+PA)≤CW≤0.4×(CL+PA), 0.6×(CL+PA)≤CH≤0.75×(CL+PA), 0.5×PA≤CW, and F1≤F2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a multi-type refrigeration apparatus and a temperature control system including a plurality of refrigeration circuits.

Background Art

[0002] An example of a multi-type refrigeration apparatus, a binary refrigeration apparatus, includes a high-temperature-side refrigeration circuit and a low-temperature-side refrigeration circuit, and constitutes a cascade condenser capable of heat-exchanging the refrigerants of each other between the evaporator of the high-temperature-side refrigeration circuit and the condenser of the low-temperature-side refrigeration circuit. In the cascade condenser, the high-temperature-side refrigerant condensed and then expanded in the high-temperature-side refrigeration circuit condenses the low-temperature-side refrigerant compressed in the low-temperature-side refrigeration circuit. The condensed low-temperature-side refrigerant is given a large degree of subcooling, and then is expanded to lower the temperature. Thus, according to the binary refrigeration apparatus, a temperature control target can be cooled to an extremely low temperature range.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the binary refrigeration apparatus includes two refrigeration circuits, it is usually larger in size than a single refrigeration apparatus. Further, in order to obtain a high refrigeration capacity, it is necessary to use a compressor with a high flow rate and a high compression ratio. In this case, in addition to further increasing the size, the component cost increases, and the energy consumption also increases.

[0005] The inventor of the present application has considered obtaining a desired refrigeration capacity while suppressing the size and energy consumption of the entire apparatus by additionally cooling the high-temperature and high-pressure low-temperature-side refrigerant flowing out from the compressor of the low-temperature-side refrigeration circuit with a cooler using water (hereinafter referred to as a water cooler). By using a water cooler, the environmental load imposed by the apparatus can also be suppressed.

[0006] However, when evaporating the refrigerant at extremely low temperatures, such as below -70°C, in the low-temperature refrigeration circuit, or when high refrigeration output is desired, it is necessary to ensure a large refrigeration capacity in the evaporator of the high-temperature refrigeration circuit as well. In other words, a large condensation load is required in the low-temperature refrigeration circuit. In this case, a water cooler does not contribute significantly to the desired condensation load. Therefore, when extremely low temperatures or high refrigeration capacity are required, a high-output or large high-temperature refrigeration circuit is ultimately necessary, and even if a water cooler is used, it is difficult to effectively suppress the size of the equipment and energy consumption.

[0007] Furthermore, the water used in the water cooler experiences temperature fluctuations depending on the season. Therefore, it may be necessary to adjust the required cooling capacity of the high-temperature side refrigeration circuit in accordance with the temperature fluctuations of the water used in the water cooler. In such cases, the adjustment range of the cooling capacity should be as small as possible compared to steady-state operation, considering the stability of the control.

[0008] Furthermore, the inventors have discovered that the settings for the refrigerant circulation rates of the high-temperature and low-temperature refrigeration circuits greatly influence the stable output of the desired refrigeration capacity, the suppression of energy consumption, the rational setting of compressor performance, and the size of the device when using a water cooler.

[0009] The inventors of this case have diligently conducted research while considering the above-mentioned problems and findings, and have found conditions under which a desired refrigeration capacity can be stably secured in a multi-compartment refrigeration system using a water cooler, while keeping the size, energy consumption, and environmental impact down.

[0010] The object of the present invention is to provide a refrigeration device and a temperature control system that can stably obtain a desired refrigeration capacity while suppressing the need for larger size, energy consumption, and environmental impact. [Means for solving the problem]

[0011] A refrigeration device according to an embodiment of the present invention includes a high-temperature side refrigeration circuit and a low-temperature side refrigeration circuit, and an evaporator of the high-temperature side refrigeration circuit and a condenser of the low-temperature side refrigeration circuit constitute a cascade condenser. The refrigeration device is provided with a water cooler that cools a low-temperature side refrigerant circulated by the low-temperature side refrigeration circuit between a compressor and a condenser in the low-temperature side refrigeration circuit. Let the refrigeration capacity of the evaporator of the low-temperature side refrigeration circuit be CL (Kw). Let the compression power of the compressor of the low-temperature side refrigeration circuit be PA (Kw). Let the cooling capacity of the water cooler be CW (Kw). Let the refrigeration capacity of the evaporator of the high-temperature side refrigeration circuit be CH (Kw). Let the refrigerant circulation amount of the high-temperature side refrigeration circuit be F1 (Kg / hour). When the refrigerant circulation amount of the low-temperature side refrigeration circuit is F2 (Kg / hour). Operation is performed under the relationships of 0.25×(CL + PA) ≤ CW ≤ 0.4×(CL + PA), 0.6×(CL + PA) ≤ CH ≤ 0.75×(CL + PA), 0.5×PA ≤ CW, and F1 ≤ F2. [[ID=I6]]

[0012] The refrigeration device according to an embodiment may be operated under the relationship of 0.5×F2 < F1 ≤ 0.7×F2.

[0013] The refrigeration device according to an embodiment may be operated by setting the refrigerant circulation amount F1 of the high-temperature side refrigeration circuit to 470 Kg / hour or more and 600 Kg / hour or less, and setting the refrigerant circulation amount F2 of the low-temperature side refrigeration circuit to 880 Kg / hour or more and 920 Kg / hour or less. [[ID=I23]]

[0014] The water cooler may cool the low-temperature side refrigerant with water in the range of 5°C or more and 28°C or less.

[0015] The water cooler may cool the low-temperature side refrigerant by flowing water from a water source without temperature adjustment.

[0016] The refrigeration capacity CL of the evaporator of the low-temperature side refrigeration circuit may be 30 Kw or less.

[0017] The refrigerating capacity CL of the evaporator of the low-temperature side refrigerating circuit may be 20 Kw or more and 30 Kw or less.

[0018] The refrigerating capacity CL of the evaporator of the low-temperature side refrigerating circuit may be 2 times or more and 3 times or less the lower limit value of the cooling capacity CW of the water cooler.

[0019] Further, in the refrigerating apparatus according to an embodiment, a low-temperature side hot gas circuit for sending the low-temperature side refrigerant flowing out from the compressor of the low-temperature side refrigerating circuit and before passing through the water cooler and the condenser of the low-temperature side refrigerating circuit to a portion on the downstream side of the expansion valve of the low-temperature side refrigerating circuit and on the upstream side of the evaporator may be further provided.

[0020] Further, a temperature control system according to an embodiment includes the refrigerating apparatus and a fluid flow device for flowing a fluid cooled by the evaporator of the low-temperature side refrigerating circuit.

Advantages of the Invention

[0021] According to the present invention, while suppressing the increase in size, energy consumption, and environmental load, a desired refrigerating capacity can be stably obtained.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram schematically showing a temperature control system including a refrigerating apparatus according to an embodiment. [Figure 2] It is a Mollier diagram for explaining the operating state of the low-temperature side refrigerating circuit constituting the refrigerating apparatus shown in FIG. 1.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings.

[0024] <Configuration of Temperature Control System and Refrigerating Apparatus> Figure 1 is a schematic diagram showing a temperature control system S equipped with a refrigeration device 10 according to one embodiment. The temperature control system S shown in Figure 1 comprises a refrigeration device 10, a water supply device 100, a fluid flow device 200, and a controller 300.

[0025] The refrigeration system 10 is a dual-stage refrigeration system. The refrigeration system 10 comprises a high-temperature side refrigeration circuit 20 and a low-temperature side refrigeration circuit 30. The refrigeration system 10 exchanges heat between the high-temperature side refrigerant circulated by the high-temperature side refrigeration circuit 20 and the low-temperature side refrigerant circulated by the low-temperature side refrigeration circuit 30 in a cascade condenser CC configured between the high-temperature side refrigeration circuit 20 and the low-temperature side refrigeration circuit 30.

[0026] The high-temperature side refrigeration circuit 20 includes a high-temperature side refrigerant circulation section 25, which is connected in order to circulate the high-temperature side refrigerant, along with a high-temperature side compressor 21, a high-temperature side condenser 22, a high-temperature side expansion valve 23, and a high-temperature side evaporator 24, as well as a subcooling circuit section 26 and a high-temperature side hot gas circuit section 27.

[0027] The supercooling circuit section 26 includes a supercooling passage 26A, a supercooling control valve 26B provided in the supercooling passage 26A, and a supercooling heat exchanger 26C provided downstream of the supercooling control valve 26B in the supercooling passage 26A. The supercooling passage 26A connects the portion downstream of the high-temperature condenser 22 and upstream of the high-temperature expansion valve 23 in the high-temperature refrigerant circulation section 25 to the high-temperature compressor 21.

[0028] The supercooling channel 26A can send a portion of the high-temperature refrigerant flowing out of the high-temperature condenser 22 to the high-temperature compressor 21. When the supercooling control valve 26B is open, it expands the high-temperature refrigerant flowing through the supercooling channel 26A, causing it to cool down, and then sends it to the supercooling heat exchanger 26C.

[0029] The subcooling heat exchanger 26C cools the high-temperature refrigerant flowing from the high-temperature condenser 22 to the high-temperature expansion valve 23 with the high-temperature refrigerant discharged from the subcooling control valve 26B. This imparts a degree of subcooling to the high-temperature refrigerant flowing from the high-temperature condenser 22 to the high-temperature expansion valve 23.

[0030] The high-temperature side hot gas circuit section 27 includes a high-temperature side hot gas passage 27A that connects the portion of the high-temperature side refrigerant circulation section 25 that is downstream of the high-temperature side compressor 21 and upstream of the high-temperature side condenser 22 with the portion of the high-temperature side refrigerant circulation section 25 that is downstream of the high-temperature side expansion valve 23 and upstream of the high-temperature side evaporator 24, and a high-temperature side hot gas control valve 27B provided in the high-temperature side hot gas passage 27A.

[0031] The high-temperature side hot gas passage 27A can send the high-temperature side refrigerant flowing out from the high-temperature side compressor 21 to a portion downstream of the high-temperature side expansion valve 23 and upstream of the high-temperature side evaporator 24. When the high-temperature side hot gas control valve 27B is open, it can mix the high-temperature side refrigerant flowing through the high-temperature side hot gas passage 27A with the high-temperature side refrigerant flowing out from the high-temperature side expansion valve 23.

[0032] The low-temperature refrigeration circuit 30 includes a low-temperature refrigerant circulation section 35, which is connected in order to circulate the low-temperature refrigerant, along with a low-temperature compressor 31, a low-temperature condenser 32, a low-temperature expansion valve 33, and a low-temperature evaporator 34; a low-temperature hot gas circuit section 36; and an injection circuit section 37.

[0033] The low-temperature side hot gas circuit section 36 includes a low-temperature side hot gas passage 36A that connects the portion of the low-temperature side refrigerant circulation section 35 that is downstream of the low-temperature side compressor 31 and upstream of the low-temperature side condenser 32 with the portion of the low-temperature side refrigerant circulation section 35 that is downstream of the low-temperature side expansion valve 33 and upstream of the low-temperature side evaporator 34, and a low-temperature side hot gas control valve 36B provided in the low-temperature side hot gas passage 36A.

[0034] The low-temperature hot gas passage 36A can send the low-temperature refrigerant flowing out of the low-temperature compressor 31 to a portion downstream of the low-temperature expansion valve 33 and upstream of the low-temperature evaporator 34. When the low-temperature hot gas control valve 36B is open, it can mix the low-temperature refrigerant flowing through the low-temperature hot gas passage 36A with the low-temperature refrigerant flowing out of the low-temperature expansion valve 33.

[0035] The injection circuit section 37 includes an injection passage 37A that connects the portion of the low-temperature refrigerant circulation section 35 that is downstream of the low-temperature condenser 32 and upstream of the low-temperature expansion valve 33, and the portion of the low-temperature refrigerant circulation section 35 that is downstream of the low-temperature evaporator 34 and upstream of the low-temperature compressor 31, and an injection control valve 37B provided in the injection passage 37A.

[0036] The injection channel 37A can send the low-temperature refrigerant flowing out of the low-temperature condenser 32 to a portion downstream of the low-temperature evaporator 34 and upstream of the low-temperature compressor 31. When the injection control valve 37B is open, the low-temperature refrigerant flowing through the injection channel 37A can be mixed with the low-temperature refrigerant flowing out of the low-temperature evaporator 34.

[0037] The cascade condenser CC described above consists of a high-temperature evaporator 24 in the high-temperature refrigeration circuit 20 and a low-temperature condenser 32 in the low-temperature refrigeration circuit 30. In the cascade condenser CC, heat exchange occurs between the high-temperature refrigerant, which has been expanded by the high-temperature expansion valve 23 to become low-temperature and low-pressure, and the low-temperature refrigerant that has flowed out from the low-temperature compressor 31. As a result, the low-temperature refrigerant flowing out of the cascade condenser CC condenses. Subsequently, the condensed low-temperature refrigerant is expanded by the low-temperature expansion valve 33 to become low-temperature and low-pressure, and flows into the low-temperature evaporator 34. The types of high-temperature and low-temperature refrigerants are not particularly limited. For example, the high-temperature refrigerant may be R449A, and the low-temperature refrigerant may be R508B.

[0038] Furthermore, the low-temperature side refrigeration circuit 30 is equipped with a water cooler 38. The water cooler 38 is a heat exchanger that receives water and low-temperature side refrigerant inside. The water cooler 38 cools the low-temperature side refrigerant with the water circulating inside before it flows into the cascade condenser CC (low-temperature side condenser 32). In other words, in the refrigeration system 10, the low-temperature side refrigerant flowing out from the low-temperature side compressor 31 is first cooled in the water cooler 38, and then cooled in the cascade condenser CC. This imparts a large degree of supercooling to the low-temperature side refrigerant. The low-temperature side hot gas flow path 36A is configured to send the low-temperature side refrigerant flowing out from the low-temperature side compressor 31 and before it passes through the water cooler 38 and the low-temperature side condenser 32 (cascade condenser CC) to the downstream side of the low-temperature side expansion valve 33 and the upstream side of the low-temperature side evaporator 34.

[0039] The water used by the water cooler 38 is supplied from the water supply device 100. The water supply device 100 is connected to the water source 101 and sends water from the water source 101 to the water cooler 38 and the high-temperature condenser 22. The water supply device 100 has a water pump 102, and water is sent to the water cooler 38 and the high-temperature condenser 22 by the drive of the water pump 102.

[0040] The water source 101 may be, for example, a tap water supply unit, a factory water supply unit, a well, or a water storage tank. In this embodiment, the water supply device 100 does not have any equipment to control the temperature of the water in consideration of energy saving. That is, the water cooler 38 cools the low-temperature side refrigerant by passing water from the water source 101 through it without temperature control. However, water temperature control equipment may be used.

[0041] When the water source 101 is a tap water supply unit, a factory water supply unit, a well, or a water storage tank, the temperature of the water supplied by the water supply device 100 can fluctuate between 5°C and 28°C depending on the season in many areas. Here, the water supply device 100 may circulate water at a rate of 10 L / min to 25 L / min. In this case, the power of the water pump 102 is relatively reduced, thus reducing energy consumption. And, within the flow rate range described above, the cooling capacity (kW) of the water supply device 100 can fluctuate between approximately 10 kW and 16 kW depending on seasonal factors.

[0042] The illustrated water supply device 100 has a first supply channel 103A and a second supply channel 103B that branch off from a common water source 101. Water from the first supply channel 103A is supplied to the water cooler 38, and water from the second supply channel 103B is supplied to the high-temperature side condenser 22. A constant flow valve 104 is also provided downstream of the water outlet in the water cooler 38. This controls the flow rate of water flowing into the water cooler 38 to a predetermined value. A configuration in which the water flow rate can be adjusted by a valve may also be adopted.

[0043] The fluid flow device 200 flows the fluid that is cooled by the low-temperature refrigerant in the low-temperature evaporator 34 of the low-temperature refrigeration circuit 30. The fluid to be flowed may be brine or the like, but is not particularly limited.

[0044] The fluid flow device 200 includes a circulation channel 201 connected to the low-temperature evaporator 34, a three-way valve 202 which forms part of the circulation channel 201, a bypass channel 203, and a circulation pump 204. The low-temperature evaporator 34 has a section for the passage of the low-temperature refrigerant and a section for the passage of the fluid. The circulation channel 201 includes an upstream channel 201U connected to one opening of the fluid passage section in the low-temperature evaporator 34, and a downstream channel 201D connected to the other opening of the fluid passage section in the low-temperature evaporator 34.

[0045] The three-way valve 202 forms part of the downstream flow path 201D between two of its three ports, and the remaining ports of the three-way valve 202 are connected to a bypass flow path 203. The bypass flow path 203 connects the three-way valve 202 to the upstream flow path 201U. A circulation pump 204 is installed in the upstream flow path 201U. Fluid flows through the flow path when the circulation pump 204 is driven.

[0046] In the fluid flow device 200, the fluid flowing in response to the operation of the circulation pump 204 is cooled by the low-temperature refrigerant in the low-temperature evaporator 34, and the fluid flowing out of the low-temperature evaporator 34 is sent to a temperature-controlled object (not shown) via the downstream flow path 201D. The fluid that has passed through the temperature-controlled object then returns to the low-temperature evaporator 34 via the upstream flow path 201U. The three-way valve 202 can adjust the flow rate of the fluid returning to the low-temperature evaporator 34 and the flow rate of the fluid that is bypassed to the downstream side of the low-temperature evaporator 34 without returning to the low-temperature evaporator 34. This makes it possible to adjust the mixing ratio of the fluid cooled in the low-temperature evaporator 34 and the fluid that is bypassed to the downstream side of the low-temperature evaporator 34 without returning to the low-temperature evaporator 34, and thus quickly adjust the temperature of the fluid sent to the temperature-controlled object.

[0047] The controller 300 controls the components of the refrigeration system 10 and the components of the fluid flow system 200. Specifically, the controller 300 can control the circulation rate (Kg / hour) of the high-temperature side refrigerant by controlling the drive state (rotation speed) of the high-temperature side compressor 21. The controller 300 can also control the opening and closing and degree of the high-temperature side hot gas control valve 27B. Furthermore, the controller 300 can control the circulation rate (Kg / hour) of the low-temperature side refrigerant by controlling the drive state (rotation speed) of the low-temperature side compressor 31. The controller 300 can also control the opening and closing and degree of the low-temperature side hot gas control valve 36B. Furthermore, the controller 300 can control the opening and closing and degree of the injection control valve 37B.

[0048] The controller 300 may be composed of a computer equipped with, for example, a CPU, ROM, RAM, etc., and may control the operations of the above-mentioned respective parts according to the stored program. Further, the controller 300 may be composed of other processors or electric circuits (for example, FPGA (Field Programmable Gate Array), etc.).

[0049] <Operating conditions> Next, the operating conditions of the refrigeration device 10 in the present embodiment will be described. That is, in the refrigeration device 10 in the present embodiment, when the refrigerating capacity of the low-temperature side evaporator 34 of the low-temperature side refrigeration circuit 30 is CL (Kw), the compression power of the low-temperature side compressor 31 of the low-temperature side refrigeration circuit 30 is PA (Kw), the cooling capacity of the water cooler 38 is CW (Kw), the refrigerating capacity of the high-temperature side evaporator 24 of the high-temperature side refrigeration circuit 20 is CH (Kw), the refrigerant circulation amount of the high-temperature side refrigeration circuit 20 is F1 (Kg / hour), and the refrigerant circulation amount of the low-temperature side refrigeration circuit 30 is F2 (Kg / hour), the operation is performed under the relationship of "0.25×(CL + PA) ≦ CW ≦ 0.4×(CL + PA), and 0.6×(CL + PA) ≦ CH ≦ 0.75×(CL + PA), and 0.5×PA ≦ CW, and F1 ≦ F2".

[0050] In particular, regarding the refrigerant circulation amount F1 of the high-temperature side refrigeration circuit 二十 and the refrigerant circulation amount F2 of the low-temperature side refrigeration circuit 30, it is desirable to perform the operation under the relationship of 0.5×F2 < F1 ≦ 0.7×F2. Specifically, for example, when the refrigerating capacity CL of the low-temperature side evaporator 34 of the low-temperature side refrigeration circuit 30 is 30 Kw or less, specifically, when it is 20 Kw or more and 30 Kw or less, the refrigerant circulation amount F1 of the high-temperature side refrigeration circuit 20 may be set to 400 Kg / hour or more and 800 Kg / hour or less, and the refrigerant circulation amount F2 of the low-temperature side refrigeration circuit 30 may be set to 780 Kg / hour or more and 1400 Kg / hour or less, and the operation may be performed.

[0051] More specifically, for example, when the refrigerating capacity CL of the low-temperature evaporator 34 is 20 Kw or more and 24 Kw, in the relationship of "0.5 × F2 < F1 ≤ 0.7 × F2", the refrigerant circulation amount F1 of the high-temperature refrigeration circuit 20 may be set to 470 Kg / hour or more and 600 Kg / hour or less, and the refrigerant circulation amount F2 of the low-temperature refrigeration circuit 30 may be set to 880 Kg / hour or more and 920 Kg / hour or less, and the operation may be performed. Note that such numerical conditions are just an example, and it is needless to say that the present invention is not limited to such conditions.

[0052] FIG. 2 is a Mollier diagram for explaining the operating state of the low-temperature refrigeration circuit 30. Referring to FIG. 2, in the low-temperature refrigeration circuit 30, in the transition shown by 1→2, the low-temperature compressor 31 compresses the low-temperature refrigerant. In the transition shown by 2→3, the low-temperature refrigerant is cooled by the water cooler 38. In the transition shown by 3→4, the cold-temperature refrigerant is cooled by the high-temperature refrigerant in the cascade condenser CC. In the transition shown by 4→5, the low-temperature refrigerant is expanded by the low-temperature expansion valve 33 and becomes a gas-liquid mixed state and becomes low-pressure and low-temperature. Then, in the transition shown by 5→1, the low-temperature refrigerant exchanges heat with the fluid passed through by the fluid flow device 200.

[0053] FIG. 2 shows the ranges corresponding to the refrigerating capacity CL (Kw) of the low-temperature evaporator 34 of the low-temperature refrigeration circuit 30 used under the operating conditions, the compression power PA (Kw) of the low-temperature compressor 31 of the low-temperature refrigeration circuit 30, the cooling capacity CW (Kw) of the water cooler 38, and the refrigerating capacity CH (Kw) of the evaporator of the high-temperature refrigeration circuit 20, respectively. The compression power PA is calculated by the refrigerant circulation amount F2 of the low-temperature refrigerant × (h2 - h1). h1 is the specific enthalpy at the point "1" in FIG. 2. h2 is the specific enthalpy at the point "2" in FIG. 2. When obtaining the compression power PA in this specification, the specific enthalpy h1 is measured by a sensor for the type of the low-temperature refrigerant and the pressure and temperature of the low-temperature refrigerant flowing out of the low-temperature evaporator 34 and flowing into the low-temperature compressor 31 before flowing in, and the position corresponding to the measured pressure and temperature of the low-temperature refrigerant is specified on the Mollier diagram (p-h diagram, refrigerant physical property data) corresponding to the low-temperature refrigerant, and thus can be obtained. The specific enthalpy 2 can be determined by measuring the type of low-temperature refrigerant and the pressure and temperature of the low-temperature refrigerant before it flows out of the low-temperature compressor 31 and into the water cooler 38 using sensors, and then identifying the position corresponding to the measured pressure and temperature of the low-temperature refrigerant on the Mollier diagram (ph diagram, refrigerant physical property data) corresponding to the low-temperature refrigerant.

[0054] The operating conditions described above are achieved by the controller 300, which primarily controls the drive state (rotational speed) of the high-temperature side compressor 21 and the low-temperature side compressor 31. When operating under these conditions, the refrigeration system 10 can achieve the desired refrigeration capacity while minimizing size, energy consumption, and environmental impact. This will be explained in more detail below.

[0055] First, the relationship "0.25 × (CL + PA) ≤ CW ≤ 0.4 × (CL + PA), and 0.6 × (CL + PA) ≤ CH ≤ 0.75 × (CL + PA)" allows us to determine the condensation load (CL + PA) required by the low-temperature refrigeration circuit 30, which is determined by the refrigeration capacity CL of the low-temperature evaporator 34 plus the compression power PA of the low-temperature compressor 31. Furthermore, this relationship allows us to determine that the burden on the cooling capacity CW (kW) of the water cooler 38 in relation to the condensation load (CL + PA) is 25% to 40%. This burden on the cooling capacity CW (kW) of the water cooler 38 is an effective condition for maximizing the refrigeration capacity CL of the low-temperature evaporator 34 while suppressing the size of the high-temperature compressor 21, the overall size of the high-temperature refrigeration circuit 20, energy consumption, environmental impact, and improving the stability of temperature control.

[0056] In other words, if the burden of the cooling capacity CW(kW) of the water cooler 38 is too large, for example, 60% or more, the low-temperature refrigerant to be condensed cannot be sufficiently subcooled, making it difficult to increase the refrigeration capacity CL of the low-temperature evaporator 34. On the other hand, if the burden of the cooling capacity CW(kW) of the water cooler 38 is too small, for example, 10% or less, the cooling of the water cooler 38 will not function effectively, and it may become necessary to use a high-performance high-temperature compressor. From this perspective, a burden of 25% to 40% of the cooling capacity CW(kW) of the water cooler 38 is favorable in terms of maximizing the refrigeration capacity CL of the low-temperature evaporator 34 while suppressing the size of the high-temperature compressor 21 and the overall size of the high-temperature refrigeration circuit 20. Furthermore, since the cooling capacity CW of the water cooler 38 bears a relatively large range of the required condensation load without requiring compression power, it is advantageous in terms of suppressing energy consumption and environmental impact.

[0057] Furthermore, when the load ratio of the cooling capacity CW(kW) of the water cooler 38 fluctuates within the range of 25% to 40%, the refrigeration capacity CH of the high-temperature evaporator 24 of the high-temperature refrigeration circuit 20 fluctuates within the range of 60% to 75% of the condensation load (CL+PA). In this case, for example, if we assume that a refrigeration capacity of 60% of the condensation load (CL+PA) is the standard operating state, the rate of change of the refrigeration capacity CH with respect to the maximum fluctuation of the cooling capacity CW of the water cooler 38 is 25%. Therefore, when the load ratio of the cooling capacity CW(kW) of the water cooler 38 is between 25% and 40%, even if the cooling capacity CW(kW) of the water cooler 38 fluctuates, there is no need to significantly adjust the refrigeration capacity CH of the high-temperature evaporator 24 of the high-temperature refrigeration circuit 20. In this case, the operating range of the high-temperature side compressor 21 can be limited to a relatively narrow range, making it possible to operate the high-temperature side compressor 21 only within a range desirable for stability, and potentially eliminating the need to ensure excessively high performance in the compressor. As a result, this is advantageous in terms of temperature control stability.

[0058] Next, in the relationship of "0.5 × PA ≤ CW", it is specified that the ratio of the cooling capacity CW (Kw) of the water cooler 38 to the compression power PA (Kw) of the low-temperature side compressor 31 is relatively large. That is, it is specified that the ratio of the cooling capacity CW (Kw) of the water cooler 38 to the compression power PA (Kw) of the low-temperature side compressor 31 is not less than half of the compression power PA (Kw) of the low-temperature side compressor 31. This relationship, as described above, means that the water cooler 38 bears a relatively large range of the condensation load for which the cooling capacity CW (Kw) is required, and it is possible to obtain a device protection function when the high-temperature side refrigeration circuit 20 fails or stops. That is, even if the high-temperature side refrigeration circuit 20 fails or stops, when the cooling capacity CW (Kw) of the water cooler 38 is not less than "0.5 × PA", by having the ability to cancel out more than half of the compression power PA of the low-temperature side compressor 31, the low-temperature side refrigerant can be cooled relatively early and the piping etc. can be protected. From this perspective, the relationship of "0.5 × PA ≤ CW" is effective.

[0059] Also, in the relationship of "F1 ≤ F2", the refrigerant circulation amount F1 (Kg / hour) of the high-temperature side refrigeration circuit 20 is not more than the refrigerant circulation amount F2 (Kg / hour) of the low-temperature side refrigeration circuit 30. Generally, in a binary refrigeration device, the refrigerant circulation amount of the high-temperature side refrigeration circuit is larger than that of the low-temperature side refrigeration circuit. In contrast, in the present embodiment, the refrigerant circulation amount F1 (Kg / hour) of the high-temperature side refrigeration circuit 20 is not more than the refrigerant circulation amount F2 (Kg / hour) of the low-temperature side refrigeration circuit 30. In this case, it is advantageous in terms of miniaturization and cost reduction of the high-temperature side refrigeration circuit 20. In particular, when the refrigeration device 10 is configured to operate in the relationship of 0.5 × F2 < F1 ≤ 0.7 × F2, it is extremely advantageous in terms of miniaturization and cost reduction.

[0060] For example, when the refrigerating capacity CL of the low-temperature evaporator 34 is 20 Kw or more and 24 Kw or less as described above, the refrigerant circulation amount F1 of the high-temperature refrigeration circuit 20 may be set to 470 Kg / hour or more and 600 Kg / hour or less, and the refrigerant circulation amount F2 of the low-temperature refrigeration circuit 30 may be set to 880 Kg / hour or more and 920 Kg / hour or less, and the operation of the refrigeration device 10 may be performed. The refrigerant circulation amount F1 of the high-temperature refrigeration circuit 20 under these numerical conditions is an extremely small setting that is not usually adopted in the high-temperature refrigeration circuit of a general binary refrigeration device with a refrigerating capacity of 20 Kw or more and 24 Kw or less. In the present embodiment, by using the water cooler 38, such an extremely small circulation amount value can be set. And, when the relationship of 0.5×F2 < F1 ≦ 0.7×F2 is satisfied, specifically, for example, when the extremely small refrigerant circulation amount F1 of the high-temperature refrigeration circuit 20 as described above is set, the high-temperature refrigeration circuit 20 can be effectively miniaturized. For example, the receiver can be omitted, or even if a receiver is used, its capacity can be kept small. Therefore, it is advantageous in terms of miniaturization and cost reduction of the high-temperature refrigeration circuit 20. Also, generally, a binary refrigeration device is configured such that the high-temperature refrigeration circuit and the low-temperature refrigeration circuit are housed in one casing. At this time, in the present embodiment, the piping members of the water supply device 100 that introduces water into the water cooler 38 and the like can also be housed in the same casing. At this time, if the high-temperature refrigeration circuit 20 is large, it becomes difficult to arrange the piping members of the water supply device 100 and the like with good space efficiency. On the other hand, in the present embodiment, by suppressing the amount of high-temperature refrigerant used and downsizing the high-temperature refrigeration circuit 20, it becomes easier to miniaturize the entire device. Further, the refrigerating capacity CL of the low-temperature evaporator 34 of the low-temperature refrigeration circuit 30 may be 2 times or more and 3 times or less the lower limit value of the cooling capacity CW of the water cooler 38. In this case, while the water cooler 38 functions effectively, good operation performance and temperature control performance can be obtained. The inventor of the present case has found such conditions through various simulations and experiments.

[0061] As described above, in the refrigeration device 10 according to the present embodiment, when the refrigerating capacity of the low-temperature evaporator 34 of the low-temperature refrigeration circuit 30 is CL (Kw), the compression power of the low-temperature compressor 31 of the low-temperature refrigeration circuit 30 is PA (Kw), the cooling capacity of the water cooler 38 is CW (Kw), the refrigerating capacity of the high-temperature evaporator 24 of the high-temperature refrigeration circuit 20 is CH (Kw), the refrigerant circulation amount of the high-temperature refrigeration circuit 20 is F1 (Kg / hour), and the refrigerant circulation amount of the low-temperature refrigeration circuit 30 is F2 (Kg / hour), the operation is performed under the relationship of "0.25×(CL + PA) ≦ CW ≦ 0.4×(CL + PA), and 0.6×(CL + PA) ≦ CH ≦ 0.75×(CL + PA), and 0.5×PA ≦ CW, and F1 ≦ F2". Thereby, while suppressing the increase in size, energy consumption, and environmental load, a desired refrigerating capacity can be stably obtained.

[0062] Particularly regarding the refrigerant circulation amount F1 of the high-temperature refrigeration circuit 20 and the refrigerant circulation amount F2 of the low-temperature refrigeration circuit 30, it is desirable to perform the operation under the relationship of 0.5×F2 < F1 ≦ 0.7×F2. In this case, it is advantageous in terms of downsizing and cost reduction of the high-temperature refrigeration circuit 20. That is, in the present embodiment, the piping members of the water supply device 100 for introducing water into the water cooler 38 can be housed in the housing that houses the high-temperature refrigeration circuit 20 and the low-temperature refrigeration circuit 30. At this time, if the high-temperature refrigeration circuit 20 is large, it becomes difficult to arrange the piping members of the water supply device 100 efficiently in terms of space. On the other hand, in the present embodiment, by suppressing the amount of high-temperature refrigerant used and downsizing the high-temperature refrigeration circuit 20, it becomes easier to reduce the size of the entire device. Specifically, the high-temperature refrigeration circuit 20 and the low-temperature refrigeration circuit 30 are connected due to the configuration of the cascade condenser CC, and the water cooler 38 is arranged in proximity thereto. When the refrigerant circulation amounts in the high-temperature refrigeration circuit 20 and the low-temperature refrigeration circuit 30 are in the above relationship, in a normal design, the low-temperature refrigeration circuit 30 is designed to be larger than the high-temperature refrigeration circuit 20. In this case, the piping of the water supply device 100 can be arranged in the space where the high-temperature refrigeration circuit 20 is recessed with respect to the low-temperature refrigeration circuit 30.

[0063] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. For example, the refrigeration system 10 in the above-described embodiment is a dual-stage refrigeration system, but the present invention can also be applied to a ternary refrigeration system. In this case, the water cooler 38 cools the refrigerant circulating in the medium-temperature refrigeration circuit and / or the refrigerant circulating in the low-temperature refrigeration circuit. [Explanation of symbols]

[0064] S...Temperature control system 10…Refrigeration equipment 20…High-temperature side refrigeration circuit 21…High-temperature side compressor 22…High-temperature side condenser 23… High-temperature side expansion valve 24…High-temperature side evaporator 25...High temperature side refrigerant circulation section 30... Low-temperature refrigeration circuit 31... Low-temperature side compressor 32... Low-temperature condenser 33... Low-temperature expansion valve 34... Low-temperature evaporator 35...Low-temperature side refrigerant circulation section 36... Low-temperature side hot gas circuit section 36A... Low-temperature side hot gas flow path 36B... Low-temperature side hot gas control valve 37…Injection circuit section 37A…Injection channel 37B... Injection control valve CC... Cascade Capacitor 100…Water supply device 101…Water source 103A…1st supply path 103B…Second supply path 200...Fluid flow device 201...Circulation channel 201U…Upstream flow path 201D… Downstream channel 202... Three-way valve 203…Bypass channel 204... Circulation pump 300... Controller

Claims

1. A refrigeration system comprising a high-temperature side refrigeration circuit and a low-temperature side refrigeration circuit, wherein the evaporator of the high-temperature side refrigeration circuit and the condenser of the low-temperature side refrigeration circuit constitute a cascade condenser, A water cooler is provided between the compressor and the condenser in the low-temperature refrigeration circuit to cool the low-temperature refrigerant circulated by the low-temperature refrigeration circuit with water. The system comprises a water supply device that supplies water to the water cooler and the condenser of the high-temperature side refrigeration circuit, Let the refrigeration capacity of the evaporator in the low-temperature refrigeration circuit be CL (kW). The compression power of the compressor in the aforementioned low-temperature side refrigeration circuit is PA (kW), The cooling capacity of the water cooler is defined as CW (kW), Let the refrigeration capacity of the evaporator in the high-temperature side refrigeration circuit be CH (kW). The refrigerant circulation rate of the high-temperature side refrigeration circuit is set to F1 (kg / hour), When the refrigerant circulation rate of the low-temperature side refrigeration circuit is F2 (kg / hour), A refrigeration system that operates under the following conditions: 0.25 × (CL + PA) ≤ CW ≤ 0.4 × (CL + PA), 0.6 × (CL + PA) ≤ CH ≤ 0.75 × (CL + PA), 0.5 × PA ≤ CW, and F1 ≤ F2.

2. The refrigeration apparatus according to claim 1, wherein operation is performed in the relationship 0.5 × F2 < F1 ≤ 0.7 × F2.

3. The refrigeration apparatus according to claim 2, wherein the refrigerant circulation rate F1 of the high-temperature side refrigeration circuit is set to 470 kg / hour or more and 600 kg / hour or less, and the refrigerant circulation rate F2 of the low-temperature side refrigeration circuit is set to 880 kg / hour or more and 920 kg / hour or less, and the apparatus is operated accordingly.

4. The refrigeration apparatus according to any one of claims 1 to 3, wherein the water cooler cools the low-temperature side refrigerant with water in the range of 5°C to 28°C.

5. The refrigeration apparatus according to any one of claims 1 to 4, wherein the water cooler cools the low-temperature side refrigerant by passing water from a water source through it without temperature control.

6. The refrigeration apparatus according to any one of claims 1 to 5, wherein the refrigeration capacity CL of the evaporator of the low-temperature side refrigeration circuit is 30 kW or less.

7. The refrigeration apparatus according to claim 6, wherein the refrigeration capacity CL of the evaporator of the low-temperature side refrigeration circuit is 20 kW or more and 30 kW or less.

8. The refrigeration apparatus according to any one of claims 1 to 7, wherein the refrigeration capacity CL of the evaporator of the low-temperature side refrigeration circuit is two times or more and three times or less the lower limit of the cooling capacity CW of the water cooler.

9. The refrigeration apparatus according to any one of claims 1 to 8, further comprising a low-temperature hot gas circuit that sends the low-temperature refrigerant, which flows out from the compressor of the low-temperature refrigeration circuit and passes through the water cooler and the condenser of the low-temperature refrigeration circuit, to a portion downstream of the expansion valve of the low-temperature refrigeration circuit and upstream of the evaporator.

10. A refrigeration apparatus according to any one of claims 1 to 9, A temperature control system comprising a fluid flow device for passing a fluid cooled by an evaporator in the low-temperature side refrigeration circuit.

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