Refrigerants for ultra-low temperature modules and ultra-low temperature modules

Abstract

The present invention provides refrigerants for ultra-low temperature modules that have a low environmental impact and high safety, even when used in ultra-low temperature modules. [Solution] In a refrigerant for ultra-low temperature modules used in an ultra-low temperature module, the freezing point of the refrigerant temperature used in the ultra-low temperature module is in the range of -80°C to -55°C, and it contains carbon dioxide and a compound containing carbon and hydrogen, and the CO2 ratio, which is the ratio of carbon dioxide to the total amount, is in the range of 13 mol% to 93 mol%.

Description

Technical Field

[0001] The present disclosure relates to a refrigerant for an ultra-low temperature module and an ultra-low temperature module.

Background Art

[0002] Conventionally, azeotropic refrigerant mixtures containing carbon dioxide and at least one flammable refrigerant and having a temperature glide (temperature gradient) are known (see, for example, Patent Document 1). Azeotropic refrigerant mixtures are used in devices such as refrigerators and freezers that require different evaporation temperatures for refrigeration and freezing. Specifically, in the azeotropic refrigerant mixture, the intermediate portion from the start of evaporation is used in the refrigeration region, and the end portion from the intermediate portion is used in the freezing region. The azeotropic refrigerant mixture is used such that the evaporator operates at an evaporation temperature of -56.6°C or higher, which is the triple point of carbon dioxide, and has a temperature glide of 20°C to 30°C.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, for a refrigerant (refrigerant for an ultra-low temperature module) used in an ultra-low temperature module such as a freezing warehouse with an ultra-low temperature (for example, an F4-class freezing warehouse with a temperature of -50°C or lower), it is desirable that the temperature gradient is small in order to maintain the cooling performance while keeping the refrigerant temperature low. In this case, it is conceivable to use a refrigerant having a single composition, but on the other hand, it is necessary to improve the environmental load and safety.

[0005] Therefore, an object of the present disclosure is to provide a refrigerant for an ultra-low temperature module and an ultra-low temperature module that can have a low environmental load and high safety even when used in an ultra-low temperature module. [Means for solving the problem]

[0006] The cryogenic module refrigerant of this disclosure is a cryogenic module refrigerant used in a cryogenic module, wherein the freezing point of the refrigerant temperature used in the cryogenic module is in the range of -80°C to -55°C, and it contains carbon dioxide and a compound containing carbon and hydrogen, and the CO2 ratio, which is the ratio of carbon dioxide to the total amount, is in the range of 13 mol% to 93 mol%.

[0007] The cryogenic module of this disclosure is a cryogenic module that utilizes the above-mentioned cryogenic module refrigerant, and comprises a high-source refrigeration cycle and a low-source refrigeration cycle, wherein the low-source refrigeration cycle utilizes the above-mentioned cryogenic module refrigerant. [Effects of the Invention]

[0008] According to this disclosure, even when used in cryogenic modules, the environmental impact can be low and the safety can be high. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a diagram relating to the cryogenic module according to this embodiment. [Figure 2] Figure 2 is a graph showing an example of the freezing point / melting point of a refrigerant for ultra-low temperature modules, which varies depending on the CO2 ratio. [Figure 3] Figure 3 is a graph showing an example of the freezing / melting point of a refrigerant for ultra-low temperature modules, which varies depending on the CO2 ratio. [Figure 4] Figure 4 is a graph showing an example of the freezing point / melting point of a refrigerant for ultra-low temperature modules, which varies depending on the CO2 ratio. [Figure 5] Figure 5 is a graph showing an example of the temperature gradient of a refrigerant for a cryogenic module. [Figure 6] Figure 6 is a graph showing an example of the temperature gradient of a refrigerant for a cryogenic module. [Figure 7]Figure 7 is a graph showing an example of the temperature gradient of a refrigerant for a cryogenic module. [Modes for carrying out the invention]

[0010] Embodiments relating to this disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit this disclosure. Furthermore, some components in the embodiments described below are substituted or substantially identical to those easily substituted by those skilled in the art. Moreover, the components described below can be combined as appropriate, and if there are multiple embodiments, each embodiment can be combined.

[0011] [This Circumstance] The ultra-low temperature module 1 according to this embodiment is, for example, a frozen warehouse of class F4 in the frozen (F) category, and is a module in which the internal temperature is -50°C or lower. Furthermore, the ultra-low temperature module is not limited to a frozen warehouse, but also includes cooling chillers used in semiconductor manufacturing equipment, and modules in which the cooling temperature is approximately -80°C. For this reason, the refrigerant for the ultra-low temperature module used in the ultra-low temperature module (hereinafter also simply referred to as the refrigerant) has a freezing point temperature in the range of -80°C to -55°C. First, the ultra-low temperature module 1 will be described with reference to Figure 1.

[0012] (Ultra-low temperature module) Figure 1 is a diagram relating to the cryogenic module according to this embodiment. As shown in Figure 1, the cryogenic module 1 is a dual refrigeration system comprising a high-source refrigeration cycle and a low-source refrigeration cycle. Specifically, the cryogenic module 1 comprises a high-source refrigeration cycle 5, a cascade heat exchanger 6, a low-source refrigeration cycle 7, an evaporator 8, and a cooler 9. Furthermore, the refrigerant for the cryogenic module in this embodiment is the low-source refrigerant used in the low-source refrigeration cycle 7. The high-source refrigerant used in the high-source refrigeration cycle 5 is a refrigerant with a single composition, such as carbon dioxide or ammonia.

[0013] The high-speed refrigeration cycle 5 compresses the high-speed refrigerant sent from the cascade heat exchanger 6, condenses the compressed high-speed refrigerant by exchanging heat with the outside air, expands the condensed high-speed refrigerant by depressurizing it, and sends the expanded high-speed refrigerant back to the cascade heat exchanger 6.

[0014] The cascade heat exchanger 6 performs heat exchange between the high-speed refrigerant sent from the high-speed refrigeration cycle 5 and the low-speed refrigerant sent from the low-speed refrigeration cycle 7. The cascade heat exchanger 6 allows the expanded high-speed refrigerant to absorb the heat from the low-speed refrigerant and evaporate it, then sends the evaporated high-speed refrigerant to the high-speed refrigeration cycle 5. The cascade heat exchanger 6 also cools the low-speed refrigerant sent from the low-speed refrigeration cycle 7 by exchanging heat with the high-speed refrigerant, causing it to condense, and then sends the condensed low-speed refrigerant to the low-speed refrigeration cycle 7.

[0015] The low-source refrigeration cycle 7 compresses the low-source refrigerant sent from the evaporator 8 and sends the compressed low-source refrigerant to the cascade heat exchanger 6. The low-source refrigeration cycle 7 also depressurizes and expands the low-source refrigerant that has condensed in the cascade heat exchanger 6, and sends the expanded low-source refrigerant to the evaporator 8.

[0016] The evaporator 8 performs heat exchange between the low-source refrigerant sent from the low-source refrigeration cycle 7 and the cooler refrigerant circulating in the cooler 9. The evaporator 8 allows the expanded low-source refrigerant to absorb the heat from the cooler refrigerant and evaporates it, then sends the evaporated low-source refrigerant back to the low-source refrigeration cycle 7. The evaporator 8 also cools the cooler refrigerant sent from the cooler 9 by exchanging heat with the low-source refrigerant, and sends the cooled cooler refrigerant back to the cooler 9.

[0017] The cooler 9 cools and blows air using a cooler refrigerant supplied from the evaporator 8. When the ultra-low temperature module 1 is a cold storage warehouse, the cooler 9 operates to cool the air inside the warehouse so that the internal temperature is below -50°C. Although the cooler 9 has been described as a device that cools air using a cooler refrigerant, it may also be a device that cools liquid using a cooler refrigerant, for example, when a cooling chiller is used as the ultra-low temperature module 1, and is not particularly limited.

[0018] (Refrigerant for cryogenic module) Next, referring to FIGS. 2 to 4, the refrigerant for the cryogenic module will be described. FIGS. 2 to 4 are graphs regarding an example of the freezing point / melting point of the refrigerant for the cryogenic module that changes according to the CO2 ratio. In FIGS. 2 to 4, the horizontal axis represents the CO2 concentration (CO2 ratio) [mol%], and the vertical axis represents the freezing point / melting point [°C]. The CO2 concentration is the ratio of the molar concentration of carbon dioxide to the total amount. Also, each point in FIGS. 2 to 4 is a measurement point obtained through various experiments and the like.

[0019] As described above, the refrigerant for the cryogenic module has a freezing point refrigerant temperature in the range of -80°C to -55°C. The refrigerant for the cryogenic module has a composition containing carbon dioxide (CO2) and a compound containing carbon and hydrogen. The compound containing carbon and hydrogen is, for example, propane, ethane, difluoromethane, etc.

[0020] FIG. 2 shows the refrigerant for the cryogenic module when the compound is propane. As shown in FIG. 2, when the freezing point refrigerant temperature of the refrigerant for the cryogenic module is in the range of -80°C to -55°C, the CO2 concentration is 15 mol% to 89 mol%.

[0021] FIG. 3 shows the refrigerant for the cryogenic module when the compound is ethane. As shown in FIG. 3, when the freezing point refrigerant temperature of the refrigerant for the cryogenic module is in the range of -80°C to -55°C, the CO2 concentration is 13 mol% to 88 mol%.

[0022] FIG. 4 shows the refrigerant for the cryogenic module when the compound is difluoromethane (R32). As shown in FIG. 4, when the freezing point refrigerant temperature of the refrigerant for the cryogenic module is in the range of -80°C to -55°C, the CO2 concentration is 55 mol% to 93 mol%.

[0023] Furthermore, it is more preferable that the refrigerant for the ultra-low temperature module has a freezing point temperature in a range lower than -56.6°C. In other words, the refrigerant for the ultra-low temperature module may have a freezing point temperature in a range between -80°C and -56.6°C.

[0024] Next, the temperature gradient of the refrigerant for the cryogenic module will be explained with reference to Figures 5 to 7. Figures 5 to 7 are graphs showing an example of the temperature gradient of the refrigerant for the cryogenic module. In Figures 5 to 7, the horizontal axis represents the CO2 concentration (CO2 ratio) [mol%], and the vertical axis represents the temperature / temperature gradient [°C / deg°C]. In Figures 5 to 7, line L1 represents the saturated gas temperature, line L2 represents the saturated liquid temperature, and line L3 represents the temperature gradient. Note that in Figures 5 to 7, the refrigerant temperature and temperature gradient are shown under saturated pressure when the refrigerant temperature is -60°C.

[0025] Figure 5 shows the refrigerant for the cryogenic module when the compound is propane. As shown in Figure 5, the refrigerant for the cryogenic module has a temperature gradient of 7°C to 34°C in the range where the CO2 concentration is 15 mol% to 89 mol%.

[0026] Figure 6 shows the refrigerant for the cryogenic module when the compound is ethane. As shown in Figure 6, the refrigerant for the cryogenic module has a temperature gradient of 0°C to 4°C in the range where the CO2 concentration is 13 mol% to 88 mol%.

[0027] Figure 7 shows the refrigerant for the cryogenic module when the compound is difluoromethane (R32). As shown in Figure 7, the refrigerant for the cryogenic module has a temperature gradient of 4°C to 17°C in the range where the CO2 concentration is 55 mol% to 93 mol%.

[0028] In this case, it is preferable that the refrigerant for the ultra-low temperature module has a CO2 concentration such that the temperature gradient is less than 20°C.

[0029] As described above, the refrigerant for the cryogenic module and the cryogenic module described in this embodiment can be understood, for example, as follows.

[0030] The cryogenic module refrigerant according to the first embodiment is a cryogenic module refrigerant used in a cryogenic module, wherein the freezing point of the refrigerant temperature used in the cryogenic module is in the range of -80°C to -55°C, and it contains carbon dioxide and a compound containing carbon and hydrogen, and the CO2 ratio, which is the ratio of carbon dioxide to the total amount, is in the range of 13 mol% to 93 mol%.

[0031] This configuration allows for the use of carbon dioxide-containing refrigerants even when used in ultra-low temperature modules, resulting in a lower environmental impact and higher safety.

[0032] In a second embodiment, in the refrigerant for the ultra-low temperature module according to the first embodiment, the freezing point is in a temperature range lower than the triple point of carbon dioxide, which is -56.6°C.

[0033] This configuration allows the refrigerant temperature to be kept low, enabling stable cooling by the cryogenic module.

[0034] In a third embodiment, in a refrigerant for a cryogenic module according to the first or second embodiment, the compound is ethane, and the CO2 ratio is in the range of 13 mol% to 88 mol%.

[0035] With this configuration, if the compound is ethane, the CO2 ratio can be set to an appropriate ratio, thereby enabling appropriate performance as a refrigerant.

[0036] In a fourth embodiment, in a refrigerant for a cryogenic module according to the first or second embodiment, the compound is propane, and the CO2 ratio is in the range of 15 mol% to 89 mol%.

[0037] With this configuration, if the compound is propane, the CO2 ratio can be set to an appropriate ratio, thereby ensuring appropriate performance as a refrigerant.

[0038] In a fifth embodiment, in a refrigerant for a cryogenic module according to the first or second embodiment, the compound is difluoromethane, and the CO2 ratio is in the range of 55 mol% to 93 mol%.

[0039] With this configuration, if the compound is difluoromethane, the CO2 ratio can be set to an appropriate ratio, thereby enabling appropriate performance as a refrigerant.

[0040] In the sixth embodiment, in a refrigerant for a cryogenic module according to any one of the first to fifth embodiments, the temperature gradient, which is the difference between the saturated gas temperature and the saturated liquid temperature, is less than 20°C.

[0041] This configuration allows for suppression of temperature changes in the refrigerant between the saturated gas temperature and the saturated liquid temperature, thereby enabling stable cooling.

[0042] The cryogenic module according to the seventh embodiment is a cryogenic module that utilizes a cryogenic module refrigerant according to any one of the first to sixth embodiments, and comprises a high-source refrigeration cycle 5 and a low-source refrigeration cycle 7, wherein the low-source refrigeration cycle 7 utilizes the cryogenic module refrigerant.

[0043] This configuration allows for cooling in the low-temperature refrigeration cycle using a refrigerant designed for ultra-low temperature modules, which has a low environmental impact and high safety. [Explanation of symbols]

[0044] 1. Cryogenic module 5. High-speed refrigeration cycle 6. Cascade Heat Exchanger 7. Low-end refrigeration cycle 8 Evaporator 9 Cooler

Claims

1. In refrigerants for ultra-low temperature modules used in ultra-low temperature modules, The freezing point of the refrigerant used in the aforementioned ultra-low temperature module is in the range of -80°C to -55°C. Carbon dioxide and, A compound containing carbon and hydrogen, CO2 is the ratio of carbon dioxide to the total amount. ２ The ratio ranges from 13 mol% to 93 mol% for refrigerants used in ultra-low temperature modules.

2. The refrigerant for an ultra-low temperature module according to claim 1, wherein the freezing point is in a temperature range lower than -56.6°C, which is the triple point of carbon dioxide.

3. The aforementioned compound is ethane, The aforementioned CO ２ The refrigerant for an ultra-low temperature module according to claim 1, wherein the ratio is in the range of 13 mol% to 88 mol%.

4. The aforementioned compound is propane, The aforementioned CO ２ The refrigerant for an ultra-low temperature module according to claim 1, wherein the ratio is in the range of 15 mol% to 89 mol%.

5. The aforementioned compound is difluoromethane, The aforementioned CO ２ The refrigerant for an ultra-low temperature module according to claim 1, wherein the ratio is in the range of 55 mol% to 93 mol%.

6. The refrigerant for an ultra-low temperature module according to claim 1, wherein the temperature gradient, which is the difference between the saturated gas temperature and the saturated liquid temperature, is less than 20°C.

7. A cryogenic module utilizing a cryogenic module refrigerant according to any one of claims 1 to 6, The refrigeration cycle on the Kogen side, Equipped with a low-end refrigeration cycle, The aforementioned low-temperature refrigeration cycle is an ultra-low temperature module that utilizes the refrigerant for the ultra-low temperature module.

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