Ultralow-temperature module refrigerant and ultralow-temperature module

Abstract

According to the present invention, an ultralow-temperature module refrigerant is to be used in an ultralow-temperature module, has a freezing point of -80°C–-55°C, and includes carbon dioxide and a compound that includes carbon and hydrogen, the percentage of carbon dioxide (CO2 percentage) being 13–93 mol% of the whole.

Description

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

[0001] This disclosure relates to refrigerants for cryogenic modules and cryogenic modules.

[0002] Conventionally, non-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). Non-azeotropic refrigerant mixtures are used in equipment that requires different evaporation temperatures for freezing and refrigeration, such as refrigerators and freezers. Specifically, non-azeotropic refrigerant mixtures are used in the freezing region from the start of evaporation to the middle portion, and in the refrigeration region from the middle portion to the end portion. Furthermore, non-azeotropic refrigerant mixtures are used so that the evaporator operates when the evaporation temperature is above the triple point of carbon dioxide, which is -56.6°C, and have a temperature glide of 20°C to 30°C.

[0003] Japanese Patent Publication No. 2004-198063

[0004] Incidentally, for refrigerants used in ultra-low temperature modules such as those found in extremely cold storage warehouses (for example, F4 class cold storage warehouses that reach temperatures below -50°C), it is desirable to have a small temperature gradient in order to maintain cooling performance while keeping the refrigerant temperature low. In this case, it is conceivable to use a refrigerant with a single composition, but on the other hand, it is necessary to improve environmental impact and safety.

[0005] Therefore, the object of this disclosure is to provide a refrigerant for ultra-low temperature modules and an ultra-low temperature module that can be used in ultra-low temperature modules with low environmental impact and high safety.

[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, with the ratio of carbon dioxide to the total amount being CO2. ２ The ratio ranges from 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.

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

[0009] Figure 1 is a diagram relating to the cryogenic module according to this embodiment. Figure 2 is CO ２ This graph shows an example of the freezing / melting points of refrigerants for ultra-low temperature modules, which vary depending on the ratio. Figure 3 shows CO ２ This graph shows an example of the freezing / melting point of a refrigerant for ultra-low temperature modules, which changes depending on the ratio. Figure 4 shows CO ２ This graph shows an example of the freezing / melting point of a refrigerant for ultra-low temperature modules, which changes depending on the ratio. Figure 5 is a graph showing an example of the temperature gradient of a refrigerant for ultra-low temperature modules. Figure 6 is a graph showing an example of the temperature gradient of a refrigerant for ultra-low temperature modules. Figure 7 is a graph showing an example of the temperature gradient of a refrigerant for ultra-low temperature modules.

[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 Embodiment] 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 or higher and -55°C or lower (-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 ultra-low temperature module according to this embodiment. As shown in Figure 1, the ultra-low temperature module 1 is a dual refrigeration system comprising a high-source refrigeration cycle and a low-source refrigeration cycle. Specifically, the ultra-low temperature 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 ultra-low temperature 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, depressurizes and expands the condensed high-speed refrigerant, 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-temperature-side refrigeration cycle 7 compresses the low-temperature-side refrigerant sent from the evaporator 8 and sends the compressed low-temperature-side refrigerant to the cascade heat exchanger 6. Further, the low-temperature-side refrigeration cycle 7 decompresses and expands the low-temperature-side refrigerant condensed in the cascade heat exchanger 6 and sends the expanded low-temperature-side refrigerant to the evaporator 8.

[0016] The evaporator 8 performs heat exchange between the low-temperature-side refrigerant sent from the low-temperature-side refrigeration cycle 7 and the refrigerant for the cooler circulating in the cooler 9. The evaporator 8 causes the expanded low-temperature-side refrigerant to receive the heat of the refrigerant for the cooler and evaporate, and sends the evaporated low-temperature-side refrigerant to the low-temperature-side refrigeration cycle 7. Further, the evaporator 8 cools the refrigerant for the cooler sent from the cooler 9 by heat exchange with the low-temperature-side refrigerant and sends the cooled refrigerant for the cooler to the cooler 9.

[0017] The cooler 9 cools the air with the refrigerant for the cooler sent from the evaporator 8 and blows the cooled air. When the ultra-low temperature module 1 is a freezer, the cooler 9 cools the air in the warehouse and operates so that the temperature in the warehouse becomes -50°C or lower. Although the cooler 9 has been described as a device that cools the air with the refrigerant for the cooler, for example, when a cooling chiller is applied as the ultra-low temperature module 1, it may be a device that cools a liquid with the refrigerant for the cooler and is not particularly limited.

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

[0019] As described above, the refrigerant for the ultra-low temperature module has a refrigerant temperature at the freezing point in the range of -80°C to -55°C. The refrigerant for the ultra-low temperature module is carbon dioxide (CO ２The composition includes a compound containing carbon and hydrogen. Examples of compounds containing carbon and hydrogen include propane, ethane, and difluoromethane.

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

[0021] Figure 3 shows a refrigerant for a cryogenic module when the compound is ethane. As shown in Figure 3, when the freezing point temperature of the refrigerant for the cryogenic module is in the range of -80°C to -55°C, CO ２ The concentration ranges from 13 mol% to 88 mol%.

[0022] Figure 4 shows the refrigerant for the cryogenic module when the compound is difluoromethane (R32). As shown in Figure 4, when the refrigerant temperature at the freezing point of the cryogenic module is in the range of -80°C to -55°C, CO ２ The concentration ranges from 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 of an example of the temperature gradient of the refrigerant for the cryogenic module. In Figures 5 to 7, the horizontal axis is CO ２ Concentration (CO ２ The ratio is expressed as [mol%], and the vertical axis represents 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 is CO ２ In the range where the concentration is between 15 mol% and 89 mol%, the temperature gradient is in the range of 7°C to 34°C.

[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 is CO ２ In the range where the concentration is between 13 mol% and 88 mol%, the temperature gradient is in the range of 0°C to 4°C.

[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 is CO ２ In the range where the concentration is between 55 mol% and 93 mol%, the temperature gradient is in the range of 4°C to 17°C.

[0028] In this case, the refrigerant for the ultra-low temperature module is CO2 with a temperature gradient less than 20°C. ２ It is preferable to use a concentration.

[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 first embodiment of the cryogenic module refrigerant 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, with the ratio of carbon dioxide to the total amount being CO2. ２ The ratio ranges from 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] As a second aspect, in the refrigerant for the ultra-low temperature module according to the first aspect, the freezing point is in a temperature range lower than -56.6°C, which is the triple point of carbon dioxide.

[0033] According to this configuration, since the refrigerant temperature can be maintained at a low temperature, stable cooling by the ultra-low temperature module can be performed.

[0034] As a third aspect, in the refrigerant for the ultra-low temperature module according to the first or second aspect, the compound is ethane, and the CO ２ ratio ranges from 13 mol% to 88 mol%.

[0035] According to this configuration, when the compound is ethane, the CO ２ ratio can be set to an appropriate ratio, so that the performance as a refrigerant can be made appropriate.

[0036] As a fourth aspect, in the refrigerant for the ultra-low temperature module according to the first or second aspect, the compound is propane, and the CO ２ ratio ranges from 15 mol% to 89 mol%.

[0037] According to this configuration, when the compound is propane, the CO ２ ratio can be set to an appropriate ratio, so that the performance as a refrigerant can be made appropriate.

[0038] As a fifth aspect, in the refrigerant for the ultra-low temperature module according to the first or second aspect, the compound is difluoromethane, and the CO ２ ratio ranges from 55 mol% to 93 mol%.

[0039] According to this configuration, when the compound is difluoromethane, the CO ２ ratio can be set to an appropriate ratio, so that the performance as a refrigerant can be made appropriate.

[0040] As a sixth aspect, in the refrigerant for the ultra-low temperature module according to any one of the first to fifth aspects, 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.

[0044] 1. Cryogenic module 5. High-temperature refrigeration cycle 6. Cascade heat exchanger 7. Low-temperature refrigeration cycle 8. Evaporator 9. Cooler

Claims

1. 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, with the ratio of carbon dioxide to the total amount being CO2. 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 compound is ethane, and the 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 compound is propane, and the CO ２ The refrigerant for ultra-low temperature modules according to claim 1, wherein the ratio is in the range of 15 mol% to 89 mol%.

5. The compound is difluoromethane, and the 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 using the cryogenic module refrigerant described in any one of claims 1 to 6, comprising a high-source refrigeration cycle and a low-source refrigeration cycle, wherein the low-source refrigeration cycle is a cryogenic module using the cryogenic module refrigerant.

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