JP7617560B2 - Refrigerants, refrigeration equipment, cargo, transport equipment, transport method and refrigeration method - Google Patents

Description

This disclosure relates to ice packs, ice packs, cargo, transport equipment, transport methods, and ice pack methods.

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 entire container in which the cooling agent is enclosed, but in this disclosure, the cooling agent refers to the cooling agent itself, and the entire combination of the cooling agent and the container in which the cooling agent is enclosed is referred to as a cooling device.

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

Patent Document 1 discloses an ice pack containing water, lithium chloride, and sodium chloride. This ice pack has a melting temperature (sometimes called the melting point) of -74°C, and is characterized by using latent heat to keep things cold near this temperature.

JP 2017-128622 A

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.

The ice pack according to one embodiment of the present disclosure contains water and lithium bromide as its main components.

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.

In one example, 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.

In one example, the ice pack further contains sodium bromide.

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.

In one example, the ice pack further contains an anti-supercooling agent.

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

The 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.

A transportation device 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.

A transportation method according to one aspect of the present disclosure includes the steps of storing the cooling device and the object to be kept cold together in a storage container, and transporting the storage container that contains both the cooling device and the object to be kept cold.

In one example, the temperature of the cooling device is -65°C or lower during the storing step.

The cooling method according to one aspect of the present disclosure includes a step of storing the cooling device and the object to be cooled together in a storage container.

The above configuration or procedure makes it possible to, for example, keep things cold at extremely low temperatures.

FIG. 4 is a diagram showing temperature changes in the ice pack according to the first embodiment for different concentrations of lithium bromide. FIG. 11 is another diagram showing the temperature change in the ice pack according to the first embodiment for each concentration of lithium bromide. FIG. 11 is yet another diagram showing the temperature change in the ice pack according to the first embodiment for each concentration of lithium bromide. FIG. 11 is yet another diagram showing the temperature change in the ice pack according to the first embodiment for each concentration of lithium bromide. FIG. 11 is yet another diagram showing the temperature change in the ice pack according to the first embodiment for each concentration of lithium bromide. FIG. 4 is a diagram showing temperature changes for different types of additives in an ice pack according to an embodiment. FIG. 11 is another diagram showing temperature changes by type of additive in the ice pack according to the embodiment. FIG. 11 is yet another diagram showing temperature changes in the ice pack according to the embodiment by type of additive. 1 is a diagram showing the effect of sodium bromide on supercooling of a cooling agent according to an embodiment. FIG. 11 is a diagram showing temperature changes associated with solidification of a cooling agent according to a second embodiment, for different concentrations of sodium bromide. FIG. 11 is a diagram showing temperature changes associated with melting of a cooling agent according to a second embodiment, for different concentrations of sodium bromide. 12(a), 12(b) and 12(c) are schematic diagrams for explaining application examples of ice packs.

<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 lithium bromide solution as a main component.

As will be described in detail later, according to the inventor's experiments, the melting point of an aqueous solution of lithium bromide is (approximately) -67°C. Therefore, by using an aqueous solution of lithium bromide as the main component of an ice pack, it is possible to achieve cooling at -67°C using latent heat. As a result, it becomes easier to keep things cold at extremely low temperatures.

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 referring to it in this way, trace amounts of components that are inevitably mixed in during manufacturing are not taken into consideration.

The term "main component" refers to a component whose mass percentage is, for example, 50% or more. Therefore, when an ice pack contains water and lithium bromide as its main components, the proportion of the total mass of water and lithium bromide (in other words, the mass of the lithium bromide aqueous solution; the same applies below) in the mass of the ice pack is 50% or more.

The mass ratio of the lithium bromide aqueous solution to the mass of the ice pack may be set appropriately. 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, making it easier to utilize the properties of the lithium bromide aqueous solution related to cooling.

In the description of this embodiment, numerical values that do not include decimals include values rounded to the nearest tenth. For example, a range of 50% or more includes 49.5%. A range of 98% or less includes 98.4%. Numeric values that include decimals include values rounded to the nearest tenth. For example, a range of 0.5% or more includes 0.45%.

The concentration of lithium bromide in the lithium bromide aqueous solution may be set as appropriate. In the description of this embodiment, the concentration 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 that contains only water and lithium bromide, so the concentration of lithium bromide in the lithium bromide aqueous solution refers to the proportion of the mass of lithium bromide to the total mass of water and lithium bromide.

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.

As can be understood from the above explanation, the ice pack 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. The specific components of the additives may vary and may be known.

The proportion of the additive mass to the ice pack mass may be set as appropriate. The proportion of the total additive mass to the ice pack mass is the opposite of the proportion of the lithium bromide aqueous solution to the ice pack mass described above, and so a detailed 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 ice pack mass. The mass of the preservative may be 0.005% to 0.02% of the ice pack mass. The mass of the colorant may be 0.05% to 0.2% of the ice pack mass.

The present disclosure proposes using a supercooling prevention agent as an additive that reduces the likelihood of supercooling. This makes it easier to freeze an ice pack whose main component is a lithium bromide aqueous solution by using a freezer that achieves a temperature of, for example, about -70°C or -80°C (without using a freezer that achieves a temperature lower than -80°C). This in turn makes it easier to use the ice pack according to the embodiment. The mass ratio of the supercooling prevention agent to the ice pack may be set appropriately depending on the specific components of the supercooling prevention agent.

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).

In the second embodiment, the sodium bromide can function as a supercooling prevention agent that reduces the likelihood of supercooling occurring in, for example, an aqueous lithium bromide 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.

Below, the ice pack according to the embodiment will be described with reference to the ice pack according to the first embodiment and the ice pack according to the second embodiment as examples of the ice pack according to the embodiment, and the usefulness of the ice pack according to the embodiment will be described with reference to experimental results, etc.

First Embodiment
An experiment was carried out to examine the temperature change of the frozen ice pack according to the first embodiment (i.e., an aqueous lithium bromide solution).

The experimental method is as follows. Various concentrations of lithium bromide aqueous solutions were prepared. For each concentration, 200 g of lithium bromide aqueous solution was sealed in a bag made of a flexible resin film. The bag containing the lithium bromide aqueous solution was placed in a freezer maintained at -130°C for a sufficient amount of 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 inside the freezer. The bags containing the lithium bromide aqueous solution were then removed from the freezer and individually placed in foam containers placed at room temperature. The container had internal dimensions of 300 mm x 200 mm x 120 mm, and was approximately sealed after the bag containing the lithium bromide aqueous solution was placed inside. The temperature of the lithium bromide aqueous solution (not the atmospheric temperature inside the container) was then continuously measured by a thermocouple in contact with the bag containing the lithium bromide aqueous solution from below.

Figures 1 to 5 show the measurement results. In these figures, 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). The multiple lines in the figures show 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.

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

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. Furthermore, results for different concentrations shown in the same figure show the results of experiments conducted at the same time.

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 its surroundings. From another perspective, the sensible heat of the solid ice pack is used to keep the container cool.

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

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

As shown in Figures 1 to 3, when the lithium bromide concentration in the lithium bromide aqueous solution is between 20% and 55%, 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.

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 ice pack temperature 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 ice pack temperature is maintained at -67°C (or a temperature close to that) is sometimes referred to as the "latent heat maintenance time."

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

The example in Figure 1 shows that in the range of 20% to 30%, the higher the concentration, the longer the latent heat retention time. The example in Figure 2 shows that in the range of 20% to 35%, the higher the concentration, the longer the latent heat retention time. In other words, the examples in Figures 1 and 2 show that in the range of 35% or less, the higher the concentration, the longer the latent heat retention time.

The example in Figure 3 shows that the latent heat retention time when the concentration is 40% is longer than when the concentration is 55%. The example in Figure 4 shows that within the concentration range of 35% to 55%, the latent heat retention time is longest when the concentration is 40%. The example in Figure 5 shows that within the concentration range of 38% to 42%, the latent heat retention time is longest when the concentration is 40%.

In view of the above, the concentration of lithium bromide 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. Furthermore, taking into account error, 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.

In Figure 4, when the concentration is 45%, the latent heat retention time is extremely short. On the other hand, when the concentration is 20% in Figures 1 and 2, and when the concentration is 42% in Figure 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 used in this experiment, 20% or more and 55% or less. As can be seen from Figures 1 and 2, the lower limit of the concentration can be set lower than 20%, the lowest concentration used in this experiment. Therefore, the concentration may be set to 10% or more and 55% or less.

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.

(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).

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. In other words, a sample with an additive concentration of 1% was prepared. In addition, multiple 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. Multiple 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 multiple test tubes were removed together from the freezer and placed at room temperature, and the temperature was measured.

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 removed from the freezer.

In the legend of FIG. 6, "None" indicates a cooling agent to which no additives have been added (the cooling agent of the first embodiment, lithium bromide aqueous solution). This is the same in the legends of the other figures described below. The other symbols in the legend of FIG. 6 will be described later.

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. The temperature of the ice pack then drops again. The stop in the drop and/or rise in the temperature of the ice pack near -98°C is due to latent heat. In this way, when the ice pack freezes, the temperature stops dropping and/or rises.

When the ice pack of the first embodiment is removed from 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 related to Figure 6, a relatively small amount (10 g) of ice pack is exposed to room temperature, so the temperature stop rising at around -67°C is not as clearly evident as compared to Figures 1 to 5.

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 cause of this is, for example, supercooling. Note that in the explanation of the embodiment, it may be stated that the main cause is supercooling.

To utilize latent heat for cooling by freezing the ice pack, for example, a freezer that can achieve a temperature equal to or lower than the temperature at which the ice pack freezes is used. Therefore, if an additive can be used to raise the temperature at which the ice pack freezes above the above temperature, the capacity of the freezer that can be used to operate the ice pack can be reduced.

(Effect of additives other than sodium bromide on supercooling)
In the legend of FIG. 6, "KHCO ₃ " 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 highly water-absorbent polymer. "PG" indicates that the additive is propylene glycol.

As shown in Figure 6, when the additive is added, there is no halt in the decrease and/or increase in temperature, which represents the latent heat associated with freezing, during the process of cooling the ice pack (time t in the range of 0:00 to 1:35). As shown by this, the additive promotes supercooling, and the ice pack does not freeze even when cooled to below -120°C. As a result, even during the process of exposing the ice pack to room temperature and the temperature of the ice pack increasing (after time 1:35), there is no halt in the increase in temperature, which represents the latent heat.

Although not shown in the figure, a total of five similar experiments were performed, including the experiment shown in Figure 6. In each experiment, the same results as those shown in Figure 6 were obtained.

The additives listed above may be used, for example, as melting point lowering agents or thickening agents in ice packs. FIG. 6 does not deny that the ice packs 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 explanation of borax as an additive described later, the occurrence of supercooling may be suppressed when the additive is at a specific concentration.

Figure 7 shows 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 maintained at -130°C.

In the experiment shown in FIG. 7, 200 g of ice pack was sealed in a bag, as in the experiment shown in FIG. 1. In addition, 2 g of additive was added to 198 g of lithium bromide aqueous solution (the lithium bromide concentration in the lithium bromide aqueous solution is 40%). In other words, the concentration of the additive in the ice pack was 1%.

In the legend for Figure 7, "AC" indicates that the additive is activated carbon. "Coffee" indicates that the additive is coffee powder.

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

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 removed from the freezer.

In the experiment shown in FIG. 8, 200 g of ice pack was sealed in a bag, as in the experiments shown in FIG. 1 and FIG. 7. Also, as in the experiment shown in 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%). In other words, the concentration of additive in the ice pack was 1%. Also, the ice pack taken out of the freezer was placed in a container made of insulating material, as in the experiment shown in FIG. 1.

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.

As shown in FIG. 8, the addition of the above additives did not have any effect on suppressing supercooling of the lithium bromide aqueous solution. The above additives may be used, for example, as supercooling inhibitors, melting point lowering agents, or preservatives in ice packs. Like FIG. 6, FIG. 8 does not deny that the ice packs according to the embodiment may contain the above additives.

Although not shown in the figure, experiments were also conducted on ice packs using borax as an additive, with various concentrations. As a result, essentially 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% by mass of a lithium bromide aqueous solution with a lithium bromide concentration of 40% and 4% by mass of a borax aqueous solution with a borax concentration of 4.5%.

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

The following experiment was carried out. 10 g of ice packs were prepared by adding sodium bromide to a lithium bromide aqueous solution with a lithium bromide concentration of 40%. Eleven types of ice packs were prepared by varying the sodium bromide concentration in the ice pack (sodium bromide aqueous solution + sodium bromide) in increments of 1% from 0% to 10%. The ice packs were adjusted to weigh 10 g, so for example, an ice pack with a sodium bromide concentration of 5% contains 9.5 g of lithium bromide aqueous solution (lithium bromide concentration is 40%) and 0.5 g of sodium bromide. The eleven types of ice packs prepared were individually placed in eleven test tubes made of resin. All eleven test tubes were placed in a freezer maintained at -80°C for 24 hours. The ice packs were then removed from the freezer and visually checked for freezing. This experiment was carried out five times in total.

Note that in the previous experiments with additives other than sodium bromide, the freezer temperature was -130°C. In the experiments here, note that the freezer temperature was -80°C, as noted above.

Figure 9 is a chart showing the experimental results. In this figure, 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.

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 higher, 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 higher, the probability that the ice pack would freeze at -80°C exceeded 50%. Furthermore, when the concentration was 6% or higher, the probability that the ice pack would freeze at -80°C was 100%.

Figures 10 and 11 show the temperature change of the ice pack of the embodiment for each concentration of sodium bromide. The horizontal and vertical axes are the same as those of Figure 6. Figure 10 corresponds to the temperature change of the ice pack during the process of cooling the ice pack in a freezer. Figure 11 corresponds to the temperature change of the ice pack when it is taken out of the freezer and left to stand.

In the experiment relating to Figures 10 and 11, 200 g of ice pack was sealed in a bag, as in the experiment relating to Figure 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, as in the experiment relating to Figure 1. Note that in this experiment as well, the temperature of the freezer was -80°C, unlike the experiment relating to Figure 1.

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 pack (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 pack (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 pack is adjusted to 200 g, so for example, a "5%" ice pack contains 190 g of lithium bromide aqueous solution (lithium bromide concentration is 40%) and 10 g of sodium bromide.

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) when time t is around 0:05 (from another perspective, in the range of -70°C to -65°C). In this way, we were able to confirm the temperature change that embodies latent heat.

We were also able to confirm the temperature change that embodies latent heat for the "LiBr 20% NaBr 10%" ice pack. However, the specific time and temperature at which the temperature change appears differs from that of the ice pack with a lithium bromide concentration of 40%.

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

As described above, sodium bromide can contribute to suppressing supercooling of ice packs whose main component is 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 (sodium bromide concentration) may be, for example, 1% or more. It has been confirmed that within this range, some effect of suppressing supercooling can be obtained (Figure 9). Furthermore, no circumstances were found within the scope of this experiment that require the specification of an upper limit value for the sodium bromide concentration. Therefore, the upper limit value may be set to 10%, which was the level used in this experiment, or twice that, 20%. Furthermore, from the perspective of ensuring the effect of suppressing supercooling, the sodium bromide concentration may be set to 5% or more or 6% or more.

(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.

Figure 12 (a) is a perspective view showing an example of a cooling device 3 that uses ice pack 1. Note that a part of the cooling device 3 is shown broken away.

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

The size, shape, and material of the sealed container 5 may be set appropriately. 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 container made of a flexible material (such as resin), or 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 blocked 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 depending on 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.

Figure 12(b) is a cross-sectional view showing an example of cargo 11 using ice pack 1.

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

Examples of the object to be kept cold include food. Examples of the food include frozen foods, frozen sweets, fresh sweets, dairy products, and fresh foods. Frozen foods are foods that are frozen for the purpose of 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 cake. 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.

In addition to food and beverages, examples of objects to be kept cold include 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 this disclosure, objects to be kept cold are not limited to food products.

The size, shape, and material of the box 15 may be set as appropriate, and for example, various known boxes may be used. Representative examples include a relatively small box (e.g., 1 m or less x 1 m or less x 1 m or less) made of polystyrene foam or cardboard, and a cooler box (ice box) that combines a plastic case with insulating material. The material of the box 15 may be one with relatively high insulating properties, or one with low insulating properties.

The positions of the object 13 to be kept cold and the cooling device 3 within 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 cold (as in the illustrated example), above, or below, or may be a combination of two or more of these. Depending on the type of object 13 to be kept cold, its packaging, and/or the configuration of the box 15, it may be possible to directly house the ice pack 1 in the box 15 (without enclosing it in the enclosure 5) rather than housing the cooling device 3 in the box 15.

Figure 12(c) is a side view showing an example of a transport device 21 that uses ice pack 1.

The transport equipment 21 has, for example, one or more cargoes 11 and one or more containers 23 that store the cargoes 11. Note that the containers 23 are also an example of a storage vessel, similar to the box 15.

Examples of transport equipment 21 include automobiles (as shown in the example), airplanes, trains, ships, and motorcycles. In FIG. 12(c), a refrigerated or freezer vehicle having a built-in container 23 is shown.

The arrangement of the cargo 11 within the container 23 may be set as appropriate. Also, instead of storing the cargo 11 in the container 23, the object to be refrigerated 13 and the cooling device 3 may be directly stored in the container 23 (without being stored in a box 15). Depending on the type of object to be refrigerated 13, 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 sealed in an enclosure 5).

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

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 cooled 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, for example.

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

The cooling device 3 (ice pack 1) may be at an appropriate temperature, for example, when cooling of the cooling device 3 is completed, or when use of the cooling device 3 begins (for example, when it is packed together with the object to be cooled 13) or immediately before that (for example, within 10 minutes of beginning 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.

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. may be used. This ultra-low temperature chiller uses a multi-stage evaporator and a mixed refrigerant to cool the supplied gas (for example, air, freon gas, liquid nitrogen, or argon gas) to a temperature of about -130°C. Then, for example, by supplying the gas cooled by the chiller around the cooling device 3, the cooling device 3 (cooling agent 1) can be cooled to the various temperatures exemplified above.

Just to clarify, a chiller includes the concept of a freezer. Although not specifically illustrated, a chiller may have, for example, as its 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 out, and an evaporator that cools the object to be cooled (the ice pack or the gas supplied around the ice pack) with the reduced pressure refrigerant. Chillers may be installed, for example, at locations where the objects to be cooled are produced or wholesaled, or at each business office of a company that handles home delivery.

The technology disclosed herein is not limited to the above embodiments and may be implemented in various ways.

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 even a small amount of lithium bromide in the ice pack, it is possible to lower the melting point and lower the temperature range in which latent heat can be utilized, compared to an ice pack consisting of only water.

1... ice pack, 3... ice pack, 5... sealed container, 11... cargo, 13... object to be kept refrigerated, 21... transportation equipment.

Claims (11)

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. 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. A cooling agent,
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. A cooling agent,
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. The ice pack according to any one of claims 1 to 3, further comprising a supercooling prevention agent. 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. 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: 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. 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. The transportation method according to claim 9 , wherein the temperature of the cooling device is −65° C. or lower in the storing step. A cooling method comprising the step of housing both the cooling device according to claim 6 and an object to be cooled in a housing container.

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