Refrigerants, refrigeration equipment, cargo, transport equipment, transport method and refrigeration method

Abstract

To increase the variety of refrigerants available for refrigerating at temperatures lower than those of general freezers (for example, -20°C).SOLUTION: A refrigerant contains water and lithium bromide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a cooling agent, a cooling device, cargo, a transport device, a transport method, and a cooling method. [Background technology]

[0002] There is known a cooling agent (sometimes called a cooling storage agent or ice pack, etc.) that is used to transport food and the like in a cooled state (for example, Patent Document 1). Note that, conventionally, the term cooling agent may refer not only to the cooling agent but also to the whole including the container in which the cooling agent is enclosed, but in this disclosure, the cooling agent refers to the cooling agent itself, and the whole including the cooling agent and the container in which the cooling agent is enclosed will be referred to as a cooling device.

[0003] In general, in commercially available cooling devices, the cooling agent is made by adding various additives to water. Examples of additives include preservatives, freezing point depressants, thickeners, antifreeze, and colorants. In the cooling device, the cooling agent is frozen in a freezer, and is packed together with the object to be cooled (e.g., food). The temperature of the freezer is generally set to -20°C to -10°C, and therefore the temperature of the cooling agent is set to -20°C to -10°C when it is first used.

[0004] Patent Document 1 discloses a cooling agent containing water, lithium chloride, and sodium chloride. This cooling agent has a melting temperature (sometimes called the melting point) of -74°C, and is characterized by using latent heat to keep things cool near this temperature. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-128622 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the demand for cryogenic storage has increased due to the need to transport vaccines at temperatures (hereinafter sometimes referred to as "cryogenic temperatures") lower than the temperature of a typical freezer (e.g., -20°C). Therefore, it is desirable to increase the variety of ice packs that can be used for cryogenic storage. [Means for solving the problem]

[0007] A cooling agent according to one embodiment of the present disclosure contains water and lithium bromide as main components.

[0008] In one example, the mass of the lithium bromide is 20% or more and 55% or less of the total mass of the water and the lithium bromide.

[0009] In one example, the mass of the lithium bromide is 39% or more and 41% or less of the total mass of the water and the lithium bromide.

[0010] In one example, the ice pack further comprises sodium bromide.

[0011] In one example, the mass of the sodium bromide is 5% or more of the total mass of the water, the lithium bromide, and the sodium bromide.

[0012] In one example, the cooling agent further includes an anti-supercooling agent.

[0013] A cooling device according to one aspect of the present disclosure includes the above-mentioned ice pack and an enclosure container in which the ice pack is enclosed.

[0014] A cargo according to one aspect of the present disclosure includes the above-mentioned cooling device, an object to be kept cold, and a storage container that contains both the cooling device and the object to be kept cold.

[0015] A transportation device according to one aspect of the present disclosure includes the above-described cooling device, an object to be kept cold, and a storage container that contains both the cooling device and the object to be kept cold.

[0016] A transportation method according to one aspect of the present disclosure includes the steps of storing the above-mentioned cooling device and the object to be kept cool in a storage container, and transporting the storage container containing both the cooling device and the object to be kept cool.

[0017] In one example, the temperature of the cooling device is −65° C. or lower in the storing step.

[0018] A cold storage method according to one aspect of the present disclosure includes a step of storing both the cold storage device and an object to be kept cold in a storage container. Effect of the Invention

[0019] According to the above configuration or procedure, for example, it is possible to keep the temperature extremely low. [Brief description of the drawings]

[0020] [Figure 1] FIG. 4 is a diagram showing temperature changes in the ice pack according to the first embodiment for different concentrations of lithium bromide. [Diagram 2] FIG. 4 is another diagram showing temperature changes in the ice pack according to the first embodiment at different concentrations of lithium bromide. [Diagram 3] FIG. 4 is yet another diagram showing temperature changes in the ice pack according to the first embodiment at different concentrations of lithium bromide. [Figure 4] FIG. 4 is yet another diagram showing temperature changes in the ice pack according to the first embodiment at different concentrations of lithium bromide. [Diagram 5] FIG. 4 is yet another diagram showing temperature changes in the ice pack according to the first embodiment at different concentrations of lithium bromide. [Figure 6] FIG. 4 is a diagram showing temperature changes for different types of additives in an ice pack according to an embodiment. [Figure 7] FIG. 11 is another diagram showing temperature changes by type of additive in the ice pack according to the embodiment. [Figure 8] FIG. 11 is yet another diagram showing temperature changes in the ice pack according to the embodiment by type of additive. [Figure 9]1 is a diagram showing the effect of sodium bromide on supercooling of a cooling agent according to an embodiment. [Figure 10] FIG. 11 is a diagram showing temperature changes associated with solidification of a cooling agent according to the second embodiment at different concentrations of sodium bromide. [Figure 11] FIG. 11 is a diagram showing temperature changes associated with melting of a cooling agent according to the second embodiment, for different concentrations of sodium bromide. [Figure 12] 12(a), 12(b) and 12(c) are schematic diagrams explaining application examples of ice packs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] <Ice pack according to the embodiment> The ice pack according to the embodiment of the present disclosure contains water and lithium bromide (LiBr) as main components. In other words, the ice pack according to the embodiment contains an aqueous solution of lithium bromide as a main component.

[0022] As described in detail later, according to the experiments of the present inventors, the melting point of the lithium bromide aqueous solution is (approximately) -67°C. Therefore, by using the lithium bromide aqueous solution as the main component of the ice pack, it is possible to perform cooling at -67°C by utilizing latent heat. As a result, it becomes easier to perform cooling at extremely low temperatures.

[0023] For convenience, in the description of the embodiments, the term "lithium bromide aqueous solution" refers to an aqueous solution consisting of only water and lithium bromide unless otherwise specified. In other words, the lithium bromide aqueous solution does not contain any components other than water and lithium bromide. In addition, when saying so, trace components that are inevitably mixed in during production are not taken into consideration.

[0024] The term "main component" refers to a component whose mass % is 50% or more, for example. Therefore, when a cooling agent contains water and lithium bromide as main components, the ratio of the total mass of water and lithium bromide (in other words, the mass of the lithium bromide aqueous solution; the same applies below) to the mass of the cooling agent is 50% or more.

[0025] The mass ratio of the lithium bromide aqueous solution to the mass of the ice pack may be appropriately set. For example, the ratio may be 50% to 100%, 80% to 100%, 90% to 100%, 95% to 100%, 98% to 100%, 90% to 98%, or 95% to 98%. With such a mass ratio, for example, the temperature change of the lithium bromide aqueous solution becomes dominant in the temperature change of the ice pack, and the properties of the lithium bromide aqueous solution related to cooling can be easily utilized.

[0026] In the description of this embodiment, a numerical value that does not include a decimal point includes a value rounded off to the nearest tenth. For example, a range of 50% or more includes 49.5%. A range of 98% or less includes 98.4%. A numerical value that includes a decimal point includes a value rounded off to the nearest tenth. For example, a range of 0.5% or more includes 0.45%.

[0027] The concentration of lithium bromide in the lithium bromide aqueous solution may be set appropriately. The concentration in the description of this embodiment is in mass percent unless otherwise specified. As described above, in the description of this embodiment, the term lithium bromide aqueous solution refers to one containing only water and lithium bromide, so the concentration of lithium bromide in the lithium bromide aqueous solution refers to the mass ratio of lithium bromide to the total mass of water and lithium bromide.

[0028] The lithium bromide concentration in the lithium bromide aqueous solution may be, for example, 10% to 55%, 20% to 55%, 20% to 42%, 35% to 42%, 38% to 42%, 39% to 41%, or 40% (39.5% to 40.4%). The significance of these values ​​will be described later.

[0029] As can be understood from the above description, the cooling agent may or may not contain other components in addition to the lithium bromide aqueous solution. Examples of the other components include one or more additives. Examples of the additives include thickeners, preservatives, and colorants. Specific components of the additives may be various and may be known.

[0030] The ratio of the mass of the additive to the mass of the ice pack may be set appropriately. The ratio of the total mass of the additives to the mass of the ice pack is the opposite of the ratio of the lithium bromide aqueous solution to the mass of the ice pack, and the explanation is omitted. For example, the mass of the thickener may be 0.5% to 5%, 1% to 3%, or 1.5% to 2% of the mass of the ice pack. The mass of the preservative may be 0.005% to 0.02% of the mass of the ice pack. The mass of the colorant may be 0.05% to 0.2% of the mass of the ice pack.

[0031] The present disclosure proposes using a supercooling prevention agent as an additive, which reduces the probability of supercooling. This makes it easier to freeze a cooling agent mainly composed of a lithium bromide aqueous solution by using a freezer that realizes a temperature of, for example, about -70°C or -80°C (without using a freezer that realizes a temperature lower than -80°C). This in turn makes it easier to use the cooling agent according to the embodiment. The mass ratio of the supercooling prevention agent to the cooling agent may be appropriately set depending on the specific components of the supercooling prevention agent.

[0032] In the following description, for convenience, among the ice packs according to the embodiments, those having specific configurations may be referred to as an ice pack of a first embodiment and an ice pack of a second embodiment, as described below. (1) First embodiment of ice pack: ice pack consisting only of an aqueous lithium bromide solution. (2) Second embodiment of ice pack: ice pack consisting only of an aqueous lithium bromide solution and sodium bromide (NaBr).

[0033] The sodium bromide in the second embodiment can function as a supercooling prevention agent that reduces the probability of supercooling occurring in, for example, a lithium bromide aqueous solution. The ratio of the mass of sodium bromide to the mass of the ice pack (or the total mass of water, lithium bromide, and sodium bromide) may be set appropriately. For example, the ratio may be 1% or more and 20%, 1% or more and 10% or less, 5% or more and 10% or less, or 6% or more and 10% or less. The significance of these numerical values ​​will be described later.

[0034] Hereinafter, the ice packs according to the embodiments will be described with reference to the experimental results, taking the ice packs according to the first embodiment and the ice packs according to the second embodiment as examples of the ice packs according to the embodiments.

[0035] First Embodiment An experiment was carried out to examine the temperature change of a frozen ice pack according to the first embodiment (that is, an aqueous lithium bromide solution).

[0036] The experimental method is as follows. Various concentrations of lithium bromide aqueous solutions were prepared. 200 g of lithium bromide aqueous solutions were sealed in bags made of flexible resin film according to the concentration. The bags containing the lithium bromide aqueous solutions were placed in a freezer maintained at -130°C for a sufficient time. This caused the lithium bromide aqueous solution to freeze and the temperature of the lithium bromide aqueous solution to become equal to the temperature in the freezer. After that, the bags containing the lithium bromide aqueous solution were taken out of the freezer and individually placed in foaming containers placed at room temperature. The container had an inner dimension of 300 mm x 200 mm x 120 mm, and was approximately sealed after containing the bags containing the lithium bromide aqueous solution. Then, the temperature of the lithium bromide aqueous solution (not the atmospheric temperature in the container) was continuously measured by a thermocouple in contact with the bag containing the lithium bromide aqueous solution from below.

[0037] 1 to 5 are diagrams showing the measurement results. In these diagrams, the horizontal axis t indicates the elapsed time in units of hours (h) and minutes (m). The vertical axis T indicates the temperature (unit: °C). A number of lines in the diagrams indicate the relationship between the elapsed time and the temperature of the lithium bromide aqueous solution obtained by measurement. The time t of 0:00 (the start of measurement) is approximately the time when the lithium bromide aqueous solution was transferred from the freezer to the container.

[0038] As indicated by the legend, in FIG. 1, results are shown for aqueous lithium bromide solutions with lithium bromide concentrations of 20%, 25%, and 30%. In FIG. 2, results are shown for aqueous lithium bromide solutions with lithium bromide concentrations of 20%, 25%, 30%, and 35%. In FIG. 3, results are shown for aqueous lithium bromide solutions with lithium bromide concentrations of 40% and 55%. In FIG. 4, results are shown for aqueous lithium bromide solutions with lithium bromide concentrations of 35%, 40%, 45%, and 55%. In FIG. 5, results are shown for aqueous lithium bromide solutions with lithium bromide concentrations of 38%, 40%, and 42%.

[0039] Note that results for the same concentration in different figures (e.g., 20% in Figure 1 and 20% in Figure 2) show results for different samples. Therefore, the difference in results for the same concentration in different figures may be used to consider errors, etc. Also, results for different concentrations shown in the same figure show the results of experiments conducted at the same time.

[0040] As shown in Figure 1, when the ice pack is transferred from the freezer to the container (at 0:00), the temperature of the ice pack (lithium bromide aqueous solution) gradually rises. In other words, the ice pack absorbs heat from the surroundings. From another perspective, the sensible heat of the solid ice pack is used to keep the temperature in the container low.

[0041] When the temperature of the ice pack reaches -67°C, it is maintained at -67°C. At this time, the ice pack gradually melts while absorbing heat from the surroundings. From another perspective, the ice pack keeps the container cool by utilizing the latent heat generated when the ice pack changes from a solid to a liquid.

[0042] The temperature of the ice pack then starts to rise again and approaches room temperature. That is, the ice pack absorbs heat from the surroundings. From another perspective, the sensible heat of the liquid ice pack is used to keep the container cool.

[0043] As shown in Figures 1 to 3, when the lithium bromide concentration in the lithium bromide aqueous solution is 20% or more and 55% or less, the temperature is maintained at a constant value (-67°C) regardless of the concentration. In other words, it was confirmed that when the concentration is within the above range, latent heat can be utilized when the temperature is -67°C.

[0044] As shown in Figures 1 to 3, no significant concentration-dependent differences were observed in the time from the start of measurement (0:00) until the temperature of the ice pack reached -67°C. On the other hand, concentration-dependent differences were observed in the time that -67°C was maintained. In the following explanation, the time that the temperature of the ice pack is maintained at -67°C (or a temperature close to that) may be referred to as the "latent heat maintenance time."

[0045] The latent heat retention time is the longest when the lithium bromide concentration in the lithium bromide aqueous solution is approximately 40%. Specifically, it is as follows.

[0046] The example in Fig. 1 shows that in the range of 20% to 30%, the higher the concentration, the longer the latent heat retention time. The example in Fig. 2 shows that in the range of 20% to 35%, the higher the concentration, the longer the latent heat retention time. That is, the examples in Fig. 1 and Fig. 2 show that in the range of 35% or less, the higher the concentration, the longer the latent heat retention time.

[0047] Also, the example in Fig. 3 shows that the latent heat maintenance time when the concentration is 40% is longer than when the concentration is 55%. The example in Fig. 4 shows that the latent heat maintenance time when the concentration is 40% is the longest in the concentration range of 35% to 55%. The example in Fig. 5 shows that the latent heat maintenance time when the concentration is 40% is the longest in the concentration range of 38% to 42%.

[0048] From the above, the lithium bromide concentration in the lithium bromide aqueous solution may be, for example, 40% (39.5% or more and 40.4% or less), which is the concentration at which the longest latent heat retention time was obtained in Figures 1 to 5, as already mentioned. In addition, taking into account errors, the concentration may be 39% or more and 41% or less, or 38% or more and 42% or less. As shown in Figure 4, the latent heat retention time when the concentration is 35% can be equivalent to the latent heat retention time when the concentration is 40%. Therefore, the concentration may be 35% or more and 42% or less.

[0049] In Fig. 4, when the concentration is 45%, the latent heat retention time is extremely short. On the other hand, when the concentration is 20% in Figs. 1 and 2, and when the concentration is 42% in Fig. 5, the latent heat retention time is clearly confirmed. Therefore, the concentration may be set to 20% or more and 42% or less. The concentration may also be set to the range in which the present experiment was conducted, that is, 20% or more and 55% or less. As can be seen from Figs. 1 and 2, the lower limit of the concentration can be set lower than 20%, which was the lowest concentration in which the present experiment was conducted. Therefore, the concentration may be set to 10% or more and 55% or less.

[0050] <Second embodiment> As described above, the ice pack of the second embodiment is obtained by adding sodium bromide to a lithium bromide aqueous solution. Sodium bromide contributes to reducing the probability of supercooling occurring in the lithium bromide aqueous solution. In the following, first, the supercooling of the lithium bromide aqueous solution and the influence of additives other than sodium bromide on supercooling are described, and then the ice pack of the second embodiment is described.

[0051] (Supercooling of lithium bromide aqueous solution) An experiment was conducted to examine the temperature change of a cooling agent according to the embodiment (a cooling agent containing an aqueous lithium bromide solution as a main component).

[0052] The experimental method is as follows. A lithium bromide aqueous solution with a lithium bromide concentration of 40% was prepared. 0.1 g of additive was added to 9.9 g of this lithium bromide aqueous solution to prepare 10 g of the ice pack according to the embodiment. That is, a sample with an additive concentration of 1% was prepared. In addition, a plurality of types of ice packs were prepared by changing the type of additive in various ways. The prepared ice packs were placed in test tubes made of resin. A plurality of test tubes holding ice packs with different types of additives were placed together in a freezer maintained at -130°C, and the temperature was measured. Furthermore, after that, the plurality of test tubes were taken out of the freezer together and placed at room temperature, and the temperature was measured.

[0053] Figure 6 shows the measurement results. The horizontal and vertical axes in these figures are the same as those in Figure 1 and others. However, the time t of 0:00 corresponds roughly to the time when the ice pack was placed in the freezer. Also, the time t of 1:35 corresponds roughly to the time when the ice pack was taken out of the freezer.

[0054] In the legend of Fig. 6, "None" indicates a cooling agent to which no additive is added (the cooling agent of the first embodiment, lithium bromide aqueous solution). The same applies to the legends of other figures described later. Other symbols in the legend of Fig. 6 will be described later.

[0055] After the ice pack of the first embodiment is placed in the freezer (after time 0:00), the temperature of the ice pack gradually drops. Then, when the temperature reaches approximately -98°C, the temperature drop stops and / or the temperature rises. After that, the temperature of the ice pack drops again. The stop in the drop and / or rise in the temperature of the ice pack near -98°C is caused by latent heat. In this way, when the ice pack freezes, the temperature stops dropping and / or rises.

[0056] When the ice pack of the first embodiment is taken out of the freezer (time 1:35), the temperature of the ice pack rises. The temperature change at this time is basically as described in the explanation of the first embodiment. However, in the experiment of FIG. 6, a relatively small amount (10 g) of ice pack is exposed to room temperature, so the temperature rise stops at around -67°C as compared to FIG. 1 to FIG. 5.

[0057] The temperature at which the ice pack in the first embodiment freezes (approximately -98°C) is lower than the temperature at which the ice pack melts (approximately -67°C). One of the causes of this is, for example, the occurrence of supercooling. In the description of the embodiment, it may be expressed as if the main cause is supercooling.

[0058] In order to utilize the latent heat for cooling by freezing the ice pack, for example, a refrigerator capable of realizing a temperature equal to or lower than the temperature at which the ice pack freezes is used. Therefore, if the temperature at which the ice pack freezes can be made higher than the above temperature by using an additive, the capacity of the refrigerator available for operating the ice pack can be reduced.

[0059] (Effect of additives other than sodium bromide on supercooling) In the legend for Figure 6, "KHCO3" indicates that the additive is potassium bicarbonate. "PEG(1)" and "PEG(2)" indicate that the additive is polyethylene glycol. "PEG(1)" and "PEG(2)" have different molecular weights. "PEG(1)" has an average molecular weight of approximately 400. "PEG(2)" has an average molecular weight of approximately 1000. "SAP" indicates that the additive is a superabsorbent polymer. "PG" indicates that the additive is propylene glycol.

[0060] As shown in Fig. 6, when the additive is added, the temperature does not stop decreasing and / or increase, which represents the latent heat associated with freezing, during the process of cooling the ice pack (time t ranges from 0:00 to 1:35). As shown by this, the additive promotes supercooling, and the ice pack does not freeze even when cooled to -120°C or lower. As a result, even during the process of exposing the ice pack to room temperature and increasing its temperature (after time 1:35), the temperature does not stop increasing, which represents the latent heat.

[0061] Although not shown in the figures, similar experiments were performed a total of five times, including the experiment shown in Fig. 6. In each experiment, the same results as those shown in Fig. 6 were obtained.

[0062] The additives listed above may be used as melting point lowering agents or thickening agents in ice packs, for example. FIG. 6 does not deny that the ice pack according to the embodiment may contain the additives. For example, supercooling can be eliminated by applying a physical impact. Also, as will be understood from the description of borax as an additive described later, the occurrence of supercooling may be suppressed when the additive is at a specific concentration.

[0063] Figure 7 is a diagram showing the effect of other additives on supercooling. In this figure, the horizontal and vertical axes are the same as those in Figure 6. However, unlike Figure 6, this figure only shows the temperature change when the ice pack is cooled in a freezer that maintains a temperature of -130°C.

[0064] In the experiment according to Fig. 7, 200g of ice pack was sealed in a bag, as in the experiment according to Fig. 1. Also, 2g of additive was added to 198g of lithium bromide aqueous solution (lithium bromide concentration in lithium bromide aqueous solution is 40%). In other words, the concentration of additive in the ice pack was 1%.

[0065] In the legend of Figure 7, "AC" indicates that the additive is activated carbon. "Coffee" indicates that the additive is coffee powder.

[0066] Since activated carbon and coffee powder are porous bodies, it was expected that they would have an effect of suppressing supercooling. However, as shown in FIG. 7, even if activated carbon and coffee powder were added, the effect of suppressing supercooling of the lithium bromide aqueous solution was not confirmed. Although not shown in particular, a total of five similar experiments were performed, including the experiment related to FIG. 7. And, in each experiment, the same results as those shown in FIG. 7 were obtained. Note that FIG. 7 does not deny that the ice pack according to the embodiment may contain activated carbon and / or coffee powder, as in FIG. 6.

[0067] Figure 8 shows the effect of other additives on supercooling. In this figure, the horizontal and vertical axes are the same as those in Figure 6. As can be seen from the temperature changes, in this figure, the time around 12:05 corresponds to the time when the ice pack was taken out of the freezer.

[0068] In the experiment according to FIG. 8, 200 g of ice pack was sealed in a bag, as in the experiments according to FIG. 1 and FIG. 7. Also, as in the experiment according to FIG. 7, 2 g of additive was added to 198 g of lithium bromide aqueous solution (lithium bromide concentration in lithium bromide aqueous solution is 40%). That is, the concentration of additive in the ice pack was set to 1%. Also, the ice pack taken out of the freezer was placed in a container made of a thermal insulating material, as in the experiment according to FIG. 1.

[0069] In the legend for Figure 8, "KCl" indicates that the additive is potassium chloride. "NaCl" indicates that the additive is sodium chloride. "Borax" indicates that the additive is borax.

[0070] As shown in Fig. 8, even if the above-mentioned additives are added, the effect of suppressing supercooling of the lithium bromide aqueous solution was not confirmed. The above-mentioned additives may be used as supercooling prevention agents, melting point lowering agents, or preservatives in ice packs, for example. Fig. 8, like Fig. 6, does not deny that the ice pack according to the embodiment may contain the above-mentioned additives.

[0071] Although not shown in the figure, experiments were also conducted on ice packs using borax as an additive, with various concentrations. As a result, basically, no effect of preventing supercooling was observed at any concentration, and supercooling was promoted, and the ice pack did not freeze. However, at a specific concentration, unlike other concentrations, an effect of suppressing supercooling was confirmed. In this case, the ice pack was made by mixing 96 mass% of lithium bromide aqueous solution with a lithium bromide concentration of 40% and 4 mass% of borax aqueous solution with a borax concentration of 4.5%.

[0072] (Effect of sodium bromide on supercooling) Unlike the various additives described above, the effect of suppressing supercooling was confirmed in the ice pack in which sodium bromide was added to the lithium bromide aqueous solution (the ice pack of the second embodiment). Specifically, the following is the result.

[0073] The following experiment was carried out. Sodium bromide was added to a lithium bromide aqueous solution with a lithium bromide concentration of 40% to prepare a 10g ice pack. The concentration of sodium bromide in the ice pack (sodium bromide aqueous solution + sodium bromide) was varied by 1% increments in the range of 0% to 10%, to prepare 11 types of ice packs. The ice packs were adjusted to be 10g, so for example, an ice pack with a sodium bromide concentration of 5% contains 9.5g of lithium bromide aqueous solution (lithium bromide concentration is 40%) and 0.5g of sodium bromide. The 11 types of ice packs prepared were individually placed in 11 test tubes made of resin. All 11 test tubes were placed in a freezer maintained at -80°C for 24 hours. After that, the ice packs were taken out of the freezer and visually checked for freezing. Such experiments were carried out five times in total.

[0074] It should be noted that in the previous experiments with additives other than sodium bromide, the freezer temperature was −130° C. In the experiments herein, as noted above, the freezer temperature was −80° C.

[0075] FIG. 9 is a chart showing the experimental results. In this chart, each row indicated by "No. 1" to "No. 5" shows the results of each of the five experiments. Each column indicated by "0%" to "10%" shows the results for different concentrations of sodium bromide. Note that "0%" corresponds to the ice pack of the first embodiment, and the others correspond to the ice pack of the second embodiment. In each box, "NG" indicates that the ice pack was not frozen. In each box, a blank space indicates that the ice pack was frozen.

[0076] As shown in this figure, when the sodium bromide concentration was 0%, the ice pack did not freeze five times. On the other hand, when the concentration was 1% or more, the ice pack froze at least once. In other words, the effect of sodium bromide in suppressing supercooling was confirmed. When the concentration was 5% or more, the probability that the ice pack would freeze at -80°C exceeded 50%. Furthermore, when the concentration was 6% or more, the probability that the ice pack would freeze at -80°C was 100%.

[0077] 10 and 11 are diagrams showing temperature changes of ice packs of the embodiment for different concentrations of sodium bromide. The horizontal and vertical axes are the same as those of FIG. 6. FIG. 10 corresponds to the temperature change of the ice pack during the process of cooling the ice pack in a freezer. FIG. 11 corresponds to the temperature change of the ice pack during the process of leaving it after being taken out of the freezer.

[0078] In the experiment according to Fig. 10 and Fig. 11, 200g of ice pack was sealed in a bag, similar to the experiment according to Fig. 1. The ice pack was then placed in a freezer maintained at a temperature of -80°C. The ice pack was then placed in an insulated container at room temperature, similar to the experiment according to Fig. 1. Note that in this experiment as well, the temperature of the freezer was -80°C, unlike the experiment according to Fig. 1.

[0079] In the legends of Figs. 10 and 11, "5%", "6%", "7%", "8%" and "9%" all indicate ice packs in which the lithium bromide concentration in the lithium bromide aqueous solution is 40%. In addition, in these ice packs, each percentage indicates the concentration of sodium bromide in the ice packs (lithium bromide aqueous solution and sodium bromide). "LiBr 20% NaBr 10%" indicates an ice pack in which the lithium bromide concentration in the lithium bromide aqueous solution is 20% and the sodium bromide concentration in the ice packs (lithium bromide aqueous solution and sodium bromide) is 10%. "EN" indicates the temperature inside the freezer in Fig. 10 and room temperature in Fig. 11. The ice packs are adjusted to weigh 200g, so for example, a "5%" ice pack contains 190g of lithium bromide aqueous solution (lithium bromide concentration is 40%) and 10g of sodium bromide.

[0080] As shown in Figure 10, for the "5%, " "6%, " "7%, " "8%", and "9%" ice packs, the temperature rises in the time range t of 1:24 to 3:51. Also, as shown in Figure 11, for the above ice packs, the temperature rise slows down (the rate of temperature change becomes smaller) around t of 0:05 (from another perspective, in the range of -70°C to -65°C). In this way, the temperature change that embodies latent heat was confirmed.

[0081] We also confirmed that the temperature change that embodies latent heat occurred for the "LiBr 20% NaBr 10%" ice pack. However, the specific time and temperature at which the temperature change occurred differed from that of the ice pack with a lithium bromide concentration of 40%.

[0082] In Figure 10, the temperature of the "0%" ice pack rises at around time t 6:18. However, in Figure 11, the temperature of the "0%" ice pack rises at a roughly constant rate, and no temperature change that embodies latent heat is apparent. In other words, the "0%" ice pack is not frozen.

[0083] As described above, sodium bromide can contribute to suppressing supercooling of a cooling agent mainly composed of a lithium bromide aqueous solution. From the above experimental results, the mass ratio of sodium bromide to the total mass of the lithium bromide aqueous solution and sodium bromide (concentration of sodium bromide) may be, for example, 1% or more. It has been confirmed that within this range, the effect of suppressing supercooling can be obtained to some extent (FIG. 9). Furthermore, from the scope of this experiment, no circumstances were confirmed that require the upper limit value of the sodium bromide concentration to be specified. Therefore, the upper limit value may be 10% as used in this experiment or twice that, 20%. Furthermore, from the viewpoint of more reliably achieving the effect of suppressing supercooling, the concentration of sodium bromide may be 5% or more or 6% or more.

[0084] (Examples of ice pack applications) Hereinafter, application examples of the ice pack according to the present embodiment will be described. Specifically, the following describes ice packs, cargo, transport equipment, transport method, and ice pack method that use the ice pack.

[0085] 12(a) is a perspective view showing an example of a cooling device 3 that uses a cooling agent 1. Note that a part of the cooling device 3 is shown in a cutaway state.

[0086] The cooling device 3 has a cooling agent 1 and an enclosure 5 in which the cooling agent 1 is enclosed. The cooling agent 1 is a cooling agent according to this embodiment, and contains an aqueous lithium bromide solution as a main component. The cooling device 3 may be of a type that can be used repeatedly, or may be of a disposable type. Note that the enclosure 5 may contain a gas (e.g., air) together with the cooling agent 1.

[0087] The size, shape, and material of the sealed container 5 may be appropriately set. For example, the sealed container 5 may be a sealed container of various known cooling devices. Specifically, for example, the sealed container 5 may be a bag-shaped one made of a flexible material (such as resin), or may be a hard-type container (as shown in the example) made of a non-flexible material (such as resin). For example, the sealed container 5 may not have an injection port (the ice pack 1 cannot be taken out without destroying the sealed container 5), or may have an injection port closed by a cap as in the example shown in the figure. For example, the shape of the sealed container 5 may be a roughly rectangular parallelepiped shape (as shown in the example), or may have a unique shape according to the application. For example, the volume of the sealed container 5 (maximum volume in the case of a flexible container) may be 10 ml or more and 1 liter or less.

[0088] FIG. 12(b) is a cross-sectional view showing an example of cargo 11 using refrigerant 1.

[0089] The cargo 11 includes, for example, one or more objects 13 to be kept cool, one or more cooling devices 3, and a box 15 that contains them all. The box 15 is an example of a storage container.

[0090] Examples of the object to be kept cold include food. Examples of the food include frozen food, frozen sweets, fresh sweets, dairy products, and fresh foods. Frozen foods are foods that are frozen for long-term storage, and before freezing, they may be unheated, heated, uncooked, or cooked. Examples of frozen sweets include ice cream. Examples of fresh sweets include cakes. Examples of dairy products include yogurt. Examples of fresh foods include fresh fish (seafood), meat, and fruits and vegetables. In FIG. 12(b), a cup of ice cream is shown as an example of the object to be kept cold 13.

[0091] Examples of objects to be kept cold include foods and beverages, as well as organs for transplantation and vaccines (containers containing organs for transplantation or vaccines). In recent years, the coronavirus vaccine, which needs to be kept at an extremely low temperature, has been a hot topic of discussion as a vaccine, and the coronavirus vaccine may be considered as an object to be kept cold. The term "cold storage" is generally used for food products, but as can be understood from the above examples, in the present disclosure, objects to be kept cold are not limited to food products.

[0092] The size, shape, and material of the box 15 may be appropriately set, and for example, various known boxes may be applied. Representative examples include a relatively small box (for example, 1 m or less × 1 m or less × 1 m or less) made of polystyrene foam or cardboard, and a cooler box (ice box) made by combining a plastic case with a heat insulating material. The material of the box 15 may be one with relatively high heat insulating properties, or one with low heat insulating properties.

[0093] The positions of the object 13 to be kept cool and the cooling device 3 in the box 15 may also be set appropriately. For example, the cooling device 3 may be located to the side of the object 13 to be kept cool (as in the illustrated example), above or below the object 13, or may be a combination of two or more of these. Depending on the type of object 13 to be kept cool, its packaging, and / or the configuration of the box 15, it is also possible to directly house the ice pack 1 in the box 15 (without enclosing it in the enclosed container 5) rather than housing the cooling device 3 in the box 15.

[0094] FIG. 12(c) is a side view showing an example of a transportation device 21 using the ice pack 1.

[0095] The transport equipment 21 has, for example, one or more cargoes 11 and one or more containers 23 that accommodate the cargoes 11. Note that the containers 23, like the boxes 15, are also an example of storage vessels.

[0096] Examples of the transport equipment 21 include an automobile (illustrated example), an airplane, a train, a ship, and a motorcycle. In Fig. 12(c), a refrigerated or freezer vehicle having a container 23 attached thereto is illustrated.

[0097] The cargo 11 may be disposed appropriately within the container 23. Also, instead of storing the cargo 11 in the container 23, the object 13 to be kept cool and the cooling device 3 may be directly stored in the container 23 (without being stored in the box 15). Depending on the type of object 13 to be kept cool, its packaging and / or the configuration of the container 23, it may also be possible to store the ice pack 1 directly in the container 23 (without being enclosed in the enclosed vessel 5).

[0098] Here, the box 15 and its contents are described as cargo 11. In other words, a relatively small item that can be carried (manually) by one person or a small number of people is exemplified as cargo. However, the cargo may be larger than such a size. For example, in FIG. 12(c), the container 23 is attached to an automobile, but it may be loaded onto and unloaded from a container ship, truck, and / or train, and this container and its contents may be considered as cargo.

[0099] The storage vessel (box 15 or container 23) may simply be insulated, or may be actively kept at a low temperature by a cooling device such as a chiller. In the latter case, the temperature of the object to be kept cold is maintained at a temperature intermediate between the target temperature of the cooling device and the temperature of the ice pack, which is lower than the target temperature.

[0100] Fig. 12(a) to Fig. 12(c) also show a transportation method and a cold storage method according to the embodiment. The transportation method has a step of cooling the cooling device 3 (Fig. 12(a)), a step of storing the cooling device 3 and the object 13 to be kept cold in a box 15 (Fig. 12(b)), and a step of transporting the box 15 storing the cooling device 3 and the object 13 to be kept cold (Fig. 12(c)). The cold storage method has a step of cooling the cooling device 3 (Fig. 12(a)), and a step of storing the cooling device 3 and the object 13 to be kept cold in a box 15 (Fig. 12(b)). The cold storage method may simply perform cold storage without transportation.

[0101] The cooling device 3 (ice pack 1) may be at an appropriate temperature, for example, when the cooling of the cooling device 3 is completed, or when the use of the cooling device 3 starts (for example, when it is packed together with the object to be cooled 13) or immediately before that (for example, within 10 minutes of starting use). For example, the temperature of the cooling device 3 may be −50° C. or lower, −65° C. or lower, −67° C. or lower, −70° C. or lower, −80° C. or lower, −100° C. or lower, or −130° C. or lower.

[0102] To cool the cooling device 3 to an extremely low temperature, for example, the "Ultra-Low Temperature Chiller Cold Wave" manufactured by ADD Co., Ltd. can be used. This ultra-low temperature chiller can cool a supplied gas (for example, air, freon gas, liquid nitrogen, or argon gas) to a temperature of about -130°C by using a multi-stage evaporator and a mixed refrigerant. Then, for example, by supplying the gas cooled by the chiller to the periphery of the cooling device 3, the cooling device 3 (the ice pack 1) can be cooled to the various temperatures exemplified above.

[0103] To clarify, a chiller includes the concept of a freezer. Although not specifically illustrated, a chiller may have, for example, as basic components, a compressor that compresses a refrigerant, a condenser that cools the compressed refrigerant, an expansion valve that reduces the pressure of the cooled refrigerant before sending it, and an evaporator that cools an object to be cooled (a cold pack or a gas supplied around the cold pack) with the reduced pressure refrigerant. The chiller may be installed, for example, at a location where an object to be cooled is produced or wholesaled, or at each office of a company that handles home delivery.

[0104] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0105] In the embodiment, the lithium bromide concentration in the lithium bromide aqueous solution is exemplified as 20% or more and 100% or less. However, the lithium bromide concentration may be less than 20%. Even in this case, for example, by including lithium bromide in the cooling agent to some extent, the melting point can be lowered and the temperature range in which the latent heat can be utilized can be lowered compared to a cooling agent consisting of only water. [Explanation of symbols]

[0106] 1...ice pack, 3...ice pack, 5...enclosed container, 11...cargo, 13...item to be kept refrigerated, 21...transportation equipment.

Claims

1. It contains water and lithium bromide as its main components. The mass of the lithium bromide in the total mass of the water and the lithium bromide is 39% or more and 41% or less. Ice pack.

2. It contains water and lithium bromide as its main components. the mass of the lithium bromide is 35% or more and 55% or less of the total mass of the water and the lithium bromide, Latent heat can be utilized in the range of -70℃ to -65℃ Ice pack.

3. A cooling agent, comprising: It contains water and lithium bromide as its main components. the mass of the lithium bromide is 20% or more and 55% or less of the total mass of the water and the lithium bromide, Latent heat can be utilized in the range of -70°C to -65°C; The total mass of the water and the lithium bromide in the mass of the ice pack is 95% or more. Ice pack.

4. A cooling agent comprising: It contains water and lithium bromide as its main components. the mass of the lithium bromide is 20% or more and 55% or less of the total mass of the water and the lithium bromide, Latent heat can be utilized in the range of -70°C to -65°C; The total mass of the water and the lithium bromide in the mass of the ice pack is 90% or more, Further comprising sodium bromide, The mass of the sodium bromide in the total mass of the water, the lithium bromide, and the sodium bromide is 5% or more. Ice pack.

5. Further contains a supercooling inhibitor. The ice pack according to any one of claims 1 to 3.

6. The ice pack according to any one of claims 1 to 5, A container in which the ice pack is sealed; A cooling device having the above structure.

7. The cooling device according to claim 6, An object to be kept cold; A storage container that stores both the cooling device and the object to be cooled; Cargo that has the following characteristics:

8. The cooling device according to claim 6, An object to be kept cold; A storage container that stores both the cooling device and the object to be cooled; A transportation device having the above structure.

9. A step of storing both the cooling device according to claim 6 and an object to be cooled in a storage container; A step of transporting the storage container that contains both the cooling device and the object to be cooled; A transportation method having the above construction.

10. In the step of storing, the temperature of the cooling device is −65° C. or lower. The method of claim 9.

11. A step of storing the cooling device according to claim 6 and an object to be cooled in a storage container. A cooling method having the above structure.

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