High humidity cooling storage system

Abstract

To provide a high-humidity cooling storage system which generates stable low-temperature, high-humidity air, thereby realizing a uniform storage space without unevenness where no wind is felt, and also making the storage clean and free from the generation of bacteria and mold. [Solution] A high-humidity cooling storage system is provided which comprises a direct-contact cooler and a bag-shaped duct placed inside the storage facility, the direct-contact cooler comprising a cooling water circulation system with a sprinkler, a water tank and a pump, a refrigerant circulation system which supplies refrigerant from the freezer to a fin coil, a heat exchanger, a fan and a filter to prevent water droplets from scattering, and the air inside the refrigerator drawn in by the fan passes through the fin coil, the heat exchanger, the sprinkler and the filter to prevent water droplets from scattering, where it is cooled and highly humidified before being sent to the bag-shaped duct, and the cooled and highly humidified air is supplied uniformly from the bag-shaped duct into the storage facility.

Description

[Technical Field]

[0001] The present invention relates to a high-humidity refrigerated storage system that can store fruits, vegetables, and flowers in a storage facility in a low-temperature, high-humidity, clean environment, maintaining their freshness for a long period of time. [Background technology]

[0002] One proposed device for long-term storage of agricultural produce by rapidly cooling it and suppressing evaporation of moisture during storage is one equipped with a container and a cooling device attached to one end of the container. The cooling device includes a refrigerator, a cooler with a sprinkler-type humidifier located above the heat exchanger of the refrigerator, and a vertically extending cooling chamber for storing the heat exchanger and humidifier. The cooling chamber has an intake port at the bottom that communicates with the container body and an outlet at the top, and supplies humidified cold air into the container body to maintain a stable low-temperature, high-humidity state (Patent Document 1).

[0003] As a high-humidity refrigerator for storing preserved items such as plants including fresh flowers, fruits and vegetables, and other fresh foodstuffs at low temperatures and high humidity, and a cooling method using the same, there has been proposed a refrigerator and cooling method which has an airtight container for storing the preserved items, an ice-making means including an ice-making water tank provided within the airtight container, and a cooling unit which is disposed within the ice-making water tank and freezes the water stored in the ice-making water tank, a water supply means for supplying water to the ice-making water tank, an overflow water tank provided below or under the ice-making water tank and which stores water that overflows from the ice-making water tank, and an air blowing means for blowing air from within the airtight container onto the ice produced in the ice-making water tank, and which stores the preserved items at a relative humidity of 90% RH or higher and a temperature of 12°C or lower (Patent Document 2).

[0004] All of these methods aim to blow low-temperature, high-humidity air onto stored items such as fruits and vegetables, plants, etc., and maintain the storage space in a low-temperature, high-humidity state. This is because harvested fruits and vegetables and flowers cannot absorb moisture through their roots, so a low-temperature, high-humidity environment is required to prevent deterioration due to heat-induced temperature rises and moisture evaporation from the leaves.

[0005] Next, in order to enable long-term storage by suppressing spoilage caused by microorganisms such as mold and bacteria while maintaining the freshness of fruits and vegetables, a storage method and storage device have been proposed that include a high-humidity storage process in which fruits and vegetables are kept in a high-humidity state in the storage space of a storehouse, a mold inspection process in which the presence or absence of mold that develops on fruits and vegetables during this high-humidity storage process, and a low-humidity storage process in which, if mold is detected during this mold inspection process, the fruits and vegetables are stored at a humidity lower than the high humidity state of the storage space (Patent Document 3).

[0006] Furthermore, in response to the need to store fruits, vegetables, and flowers stably for long periods of time, the applicant has developed a refrigerator compartment that uses a direct-contact high-humidity cooler that maintains a low-temperature, high-humidity environment inside the refrigerator without the need for humidification or defrosting (Patent Document 4). The lower the environment, the greater the change in relative humidity in response to a change in temperature, and high-rise refrigerator compartments have large surface areas of exterior walls and ceilings, making it difficult to consistently maintain the temperature of 0 to 1°C and relative humidity of 95 to 99%, which are necessary for long-term refrigeration of fresh produce, due to heat entering from outside. In response, the refrigerator compartment has a double structure surrounded by an independent air-conditioned space, which completely eliminates the effects of heat entering from outside, and furthermore, the double ceiling creates a downflow air current, thereby achieving uniform temperature and humidity inside the refrigerator compartment.

[0007] Patent Document 3 discloses a storage method in which the storage environment is made low humidity when corrosion caused by mold, bacteria, etc. is detected in stored items, but this is a method that slows down corrosion and does not eliminate bacteria and mold (fungi) floating in the storage facility. In order to eliminate bacteria and mold using existing air purification systems in industrial use, so-called "clean rooms" have to be introduced, but the use of clean rooms in storage facilities for fresh produce and flowers is unrealistic due to the large-scale equipment and enormous initial costs.

[0008] Therefore, there is a demand for a low-cost, simple system that can realize a storage facility with a low-temperature, high-humidity, clean environment. Also, although the air supplied to the storage facility is low-temperature and high-humidity, the wind speed and circulation of the air are often not taken into consideration. Direct exposure to the wind can dry out the stored items, and uneven temperature and humidity can accelerate the deterioration of the stored items. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Utility Model Registration No. 3199521 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-3052 [Patent Document 3] Japanese Patent Application Publication No. 2019-190681 [Patent Document 4] Patent No. 7573302 Summary of the Invention [Problem to be solved by the invention]

[0010] Because a low-temperature, high-humidity environment is required to preserve the freshness of fruits, vegetables, and flowers, cooling devices that create low-temperature, high-humidity air have been developed, but no consideration has been given to the cooling system of the entire refrigerated storage facility, such as air cleanliness, airflow in the storage area, or uneven temperature and humidity.As a result, even in a low-temperature, high-humidity environment, decay and deterioration caused by bacteria and mold (fungi) floating inside the facility, and drying out of stored items due to the strength of the wind hitting them are common.

[0011] As mentioned in the background art, although there are storage facilities that achieve low temperatures and high humidity, there have been no storage facilities with a high level of cleanliness comparable to that of a clean room. The problem that the present invention aims to solve is to provide a high-humidity refrigerated storage system that generates stable low-temperature, high-humidity air, thereby realizing a uniform storage space without the feeling of wind, and making it a clean storage facility that does not develop bacteria or mold. [Means for solving the problem]

[0012] In order to solve the above-mentioned conventional problems, the present invention provides a high-humidity cooling storage system comprising a direct-contact cooler and a bag-shaped duct (hereinafter referred to as a sock duct) placed inside a storage facility, the direct-contact cooler comprising a cooling water circulation system including a sprinkler, a water tank and a pump, a refrigerant circulation system that supplies refrigerant from a refrigerator to a fin coil, a heat exchanger, a fan and a filter to prevent water droplets from scattering, the air inside the storage facility drawn in by the fan comes into direct contact with the cooling water in the fin coil, the heat exchanger and the sprinkler, whereby it is cooled and highly humidified, and then sent to the sock duct through the filter to prevent water droplets from scattering, and the cooled and highly humidified air is supplied uniformly from the sock duct into the storage facility.

[0013] Here, the term "direct contact type cooler" means that the cooling water and air come into direct contact in the cooler, thereby lowering the temperature of the air and increasing its humidity.

[0014] The direct contact cooler of the present invention comprises a cooling water circulation system including a sprinkler, a water tank and a pump, a refrigerant circulation system that supplies refrigerant from the refrigerator to the fin coil, a heat exchanger, a fan and a filter for preventing water droplets from scattering, but the fan does not necessarily have to be integrated with the cooler, and may be provided with a ventilation hole at the bottom of the cooler and placed separately outside the ventilation hole.

[0015] Here, a sock duct is literally a bag-shaped duct made of cloth or nonwoven fabric, and is placed near the ceiling of the storage facility. The sock duct bag is hollow, with one end closed and the other end connected to the air outlet side of a direct contact cooler, allowing the bag to be filled with low-temperature, high-humidity air. The air supplied to the storage facility is diffused evenly throughout the sock duct. Installation of the sock duct can be completed simply by attaching it to the cooler's air outlet, greatly contributing to shortening construction time and reducing costs.

[0016] The refrigerator is installed outside the storage facility, separated by an insulating panel, and cooled refrigerant circulates between it and the fin coil located inside the storage facility. The fin coil is a typical one made of copper coil and aluminum fins, and the refrigerant from the refrigerator circulates through the copper coil. However, the material of the fin coil is not important as long as it is a typical material, such as copper pipe, aluminum pipe, or a combination of SUS pipe and copper fin, aluminum fin, or SUS fin.

[0017] Water from the water tank is pumped up to the sprinkler by the pump, and then sprinkled from the sprinkler onto the heat exchanger, where heat is exchanged between the water from the sprinkler and the air drawn in by the fan and cooled by the fin coil, further cooling and humidifying the air, and raising the temperature of the water.

[0018] The water, whose temperature has risen in the heat exchanger, is cooled to 0°C by the fin coil and drips into the water tank, before being supplied again by the pump to the sprinkler. The circulating water is continuously cooled by the fin coil, forming a falling film. The circulating water is constantly sprayed onto the fin coil, creating a pseudo-defrosting effect and reducing the risk of the fin coil freezing. The fin coil also improves the air-water contact efficiency and provides dust collection benefits. Furthermore, in areas of the fin coil that are not exposed to water, heat exchange occurs between the air and the fin coil surface, cooling the air to temperatures below 0°C. At this time, there are areas in the heat exchanger where the air temperature is lower than the water temperature (minimum 0°C), which causes the air to move in the direction of heating and humidification. As a result, the air blown out from the cooler is highly humidified, close to saturation, making it possible to produce blown air with a relative humidity of 99.9% RH.

[0019] The air drawn into the storage facility by the fan comes into contact with the cooling water flowing through the fin coil, or is cooled by direct contact with the fin coil, and then heads to the heat exchanger.The air then exchanges heat with the cooling water from the sprinkler that flows into the heat exchanger, bringing the temperature close to 0°C and increasing the humidity, before leaving the heat exchanger and passing through the sprinkler and a filter to prevent water droplets from scattering, filling the sock duct, where the low-temperature, high-humidity air is uniformly supplied into the storage facility through the gaps in the cloth and non-woven fabric that make up the sock duct, filling the interior of the storage facility.

[0020] The filler material used in the heat exchanger has a special shape, with a regular internal structure that allows independent water flow (flow paths). A drop of water dropped onto one point in the heat exchanger spreads in a straight line. As a result, water passing through the first layer of filler forms a multi-layered, planar water flow. If the second layer of filler is rotated 90 degrees from the first layer, the water flows vertically and horizontally in a dense, checkerboard pattern after passing through the second layer. In the heat exchanger of the present invention, two or more layers of the above-described filler are installed as internal filler, achieving a very fine, checkerboard-like water flow. This eliminates water drift and improves the efficiency of heat exchange between water and air. As a result, high cooling efficiency can be achieved even when the temperature difference between water and air is small, and the amount of dehumidification is reduced, allowing for the supply of air with higher humidity. Furthermore, improved water-air contact efficiency also improves the dust collection effect of air spraying.

[0021] In the present invention, a water droplet prevention filter is installed above the sprinkler. This is because, without a water droplet prevention filter, the water used for sprinkling would turn into tiny droplets and be supplied to the storage facility along with the air from the cooler's outlet. Therefore, when using conventional coolers, water droplets would adhere to the sock duct, hindering the diffusion of low-temperature, high-humidity air from the sock duct, resulting in partial blockage or mold growth within the sock duct itself. The installation of a water droplet prevention filter prevents these problems. Furthermore, this water droplet prevention filter not only prevents water droplets from being carried into the sock duct, but also reduces the introduction of bacteria and mold through the filter's dust-collecting effect.

[0022] This invention enables low-temperature, high-humidity air to be uniformly supplied to the storage facility through the sock duct, while achieving clean supply air, a feat not possible with conventional technology. Clean supply air is achieved in four stages. In the first stage, dust is collected from the air by highly efficient contact between the dripping water and air in the fin coil. In the second stage, dust is collected from the air by highly efficient contact between the fine grid-patterned flowing water and air in the heat exchanger. In the third stage, dust is collected by a water droplet prevention filter installed above the sprinkler. The water droplet prevention filter prevents minute water droplets from the sprinkler from being sucked into the sock duct, but it also collects dust from the air. In the fourth stage, dust is collected by the sock duct. The sock duct is made of cloth or nonwoven fabric, and when low-temperature, high-humidity air is supplied uniformly to the storage facility through the gaps in the cloth or nonwoven fabric, it also collects dust from the air.

[0023] Depending on the surrounding environment of the storage facility to which the high-humidity refrigerated storage system of the present invention is applied, the cleanliness level inside the storage facility may be reduced when the storage facility door is opened to take stored items in and out. In such cases, creating a positive pressure inside the storage facility is effective in maintaining the cleanliness level. This is the same concept as creating a positive pressure inside a so-called "clean room" to prevent contamination when people enter and exit the room.

[0024] The high humidity refrigerated storage system of the present invention is positively pressurized by drawing in outside air into the cooler. The air circulating between the cooler and the storage facility and the drawn-in outside air are mixed in the cooler, and then purified by the four-stage dust collection means described above, and supplied to the storage facility as clean air. The specific system for positive pressure will be described in detail later in the "Modes for Carrying Out the Invention" section. [Effects of the Invention]

[0025] Due to the highly efficient contact between the cooling water and air in the fin coil and heat exchanger, low-temperature, high-humidity air with a temperature as close to 0°C and a relative humidity as close to 99.9%RH is supplied uniformly and evenly into the storage facility from the sock duct.

[0026] The dust collection effect of the fin coil, heat exchanger, anti-water droplet filter, and sock duct prevents bacteria and mold from being brought into the storage facility, creating a clean refrigerated space. This prevents stored fruits, vegetables, and flowers from deteriorating.

[0027] Even if there is a concern about contamination when opening the storage door to take stored items in and out, by creating positive pressure inside the storage room, contamination from outside can be prevented and cleanliness can be maintained. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a cross-sectional view of a high humidity refrigerated storage system of the present invention. [Figure 2] 1 is a cross-sectional view showing the structure of a cooler used in the high-humidity refrigerated storage system of the present invention. [Figure 3] FIG. 2 is a plan view showing an example of the structure of a filler used in a heat exchanger of the high-humidity refrigerated storage system of the present invention. [Figure 4] FIG. 4 is a plan view of an example of a high humidity refrigerated storage system of the present invention that employs a positive pressure system. [Figure 5]FIG. 5 is a plan view of another example of a high humidity refrigerated storage system of the present invention that employs a positive pressure system. [Figure 6] In the example of Figure 5, the path through which outside air is blown into the water tank of the cooler is enlarged. DETAILED DESCRIPTION OF THE INVENTION

[0029] An example of an embodiment of a high-humidity refrigerated storage system according to the present invention will be described below with reference to the drawings. Figure 1 is a cross-sectional view of a high-humidity refrigerated storage system 1 of the present invention installed in a storage facility, which comprises a direct-contact cooler 2 including a refrigerator 11 installed outside the heat-insulating panel 4 of the storage facility, and a sock duct 3 made of nonwoven fabric that is connected to the air outlet of the cooler 2 and extends into the storage facility.

[0030] At the bottom of Figure 1, it is noted that the flow of wind (air) is indicated by solid arrows and the flow of water by dashed arrows. The wind from sock duct 3, the results of which will be shown later, is a very weak flow that slowly descends inside the storage facility, is then sucked in by fan 16, rises against the cooling water inside cooler 2, and returns to the sock duct.

[0031] Figure 2 is a cross-sectional view showing the structure of a direct-contact cooler 2 used in a high-humidity refrigerated storage system. The first component is a refrigerant circulation system 13 in which a refrigerant is supplied to a finned coil 12 from a refrigerator 11 installed outside the storage facility's insulation panel 4 and then returned to the refrigerator. The second component is a cooling water circulation system 18 in which cooling water is pumped up from a water tank 19 by a pump 17 and sprayed by a sprinkler 15. The third component is a system for circulating low-temperature, high-humidity air. Air from inside the storage facility is drawn in by a fan 16, cooled by the finned coil 12, further cooled in a heat exchanger 14, and then passes through the sprinkler 15 and anti-water droplet scattering filter 20 to fill a sock duct 3 through an outlet 21 of the cooler 2 and diffuse evenly throughout the storage facility through gaps in the nonwoven fabric of the sock duct 3.

[0032] Here, the refrigerant used in the refrigerator is chlorofluorocarbon, but it can also be carbon dioxide (CO2), and is not particularly limited. The refrigerant circulates through the coils that make up the fin coil, and the coils and fins cool the air.

[0033] The filler material used for the heat exchanger is made of polyvinyl chloride resin. However, it is sufficient if the internal structure is regular, the water flow (flow path) is independent, and water dropped at one point on the heat exchanger spreads in a straight line. Polypropylene or polyethylene resin, or metal or ceramic may also be used. However, resin filler is more corrosion-resistant than metal. Resin filler is also easier to handle because its weight per unit volume is lighter than metal filler. The filler distributes water from the sprinkler evenly, increasing the efficiency of contact between the air and water.

[0034] An example of the structure of a heat exchanger packing material is shown in Figure 3. Hexagonal honeycombs are arranged in a close-packed structure. In Figure 3, when cooling water is dropped perpendicular to the paper surface, it enters the hexagonal honeycombs and spreads out in a vertical line as it flows downward. Because the hexagonal honeycombs are formed in multiple rows, the water flows in a vertical direction with multiple overlapping layers. If the second layer of packing material is installed rotated 90 degrees from the first layer, half of the multiple overlapping vertical flows are rotated 90 degrees and spread out horizontally, converting the overall flow into a grid pattern.

[0035] The filter used to prevent water droplets from scattering is made of three-dimensionally formed polyvinylidene chloride resin fibers, but it is not limited to this and can also be made of vinyl chloride resin, saran resin, polypropylene resin, PET resin, polyethylene resin, or a so-called HEPA filter made of glass fiber.Here, a polyvinylidene chloride resin filter was used because it has a large surface area and very little resistance (pressure loss) as an air filter, but is also good at adsorbing particles and mist.

[0036] The length of the sock duct is adjusted to match the length of the storage facility. Nonwoven fabric was used because it is expected to have a high dust collection effect, including bacteria, based on the absorption effect of nonwoven fabric, but regular cloth sock ducts can also be used, although they have a lower dust collection effect.

[0037] Measurements of the environment inside the storage facility revealed that the temperature was between 0°C and 1°C, and the relative humidity was in the range of 99.0%RH to 99.9%RH. Additionally, the air flow coming from the sock duct had a velocity (per second) ranging from 0.01m / s to 0.2m / s. These conditions proved to be extremely suitable for the long-term storage of fruits, vegetables, and flowers.

[0038] The water in the tank needs to be replaced periodically because the quality of the water stored in the tank gradually deteriorates due to the dust collection effect of the fin coil 12 and heat exchanger 14. Water supply and drainage can also be automated by installing water supply and drainage pipes at the bottom of the tank and attaching an electric valve.

[0039] If the filtering function of the anti-water droplet scattering filter deteriorates due to dust collection, remove the filter and replace it, and then clean the deteriorated filter.

[0040] Sock ducts require periodic replacement, but if they become clogged or otherwise deteriorate, the nonwoven sock duct itself can be immediately replaced, and in the case of cloth ducts, they can be reused by cleaning them after replacement.In the case of the high-humidity refrigerated storage system of the present invention, a first-stage dust collection mechanism using fin coils, a second-stage dust collection mechanism using a heat exchanger, and a third-stage dust collection mechanism using a water droplet scattering prevention filter are installed before the fourth-stage dust collection mechanism using the sock duct, so sock duct replacement frequency can be reduced, and running costs can also be expected to be reduced.

[0041] When operating the high humidity refrigeration storage system of the present invention, stored items will naturally be taken in and out of the storage facility, which may cause a decrease in the cleanliness of the storage facility. However, if there is a risk of contamination when the storage facility door is opened, this effect can be minimized by maintaining positive pressure inside the storage facility.

[0042] The positive pressure system within the storage facility will now be described. Figure 4 shows a plan view of an example of a high-humidity refrigerated storage system of the present invention that employs a positive pressure system. In this positive pressure system, an outside air intake pipe 22 is inserted through the storage facility's insulation panel 4 to just before the intake port of the fan 16 of the cooler 2. Because the fan's suction reduces the pressure just before the fan, outside air is automatically drawn into the cooler. The circulating air within the storage facility drawn in by the fan is simultaneously drawn into the cooler and mixed with outside air. This clean air is then supplied to the storage facility through a four-stage purification process consisting of the fin coil 12, heat exchanger 14, anti-water droplet filter 20, and sock duct 3. During operation, the fan operates continuously to prevent temperature and humidity fluctuations within the storage facility. This maintains positive pressure within the storage facility and prevents backflow of air through the outside air intake pipe. Since outside air is constantly drawn in while the fan 16 is operating, the storage facility is kept under positive pressure. When the positive pressure level exceeds a predetermined pressure, the differential pressure damper 23 is configured to exhaust the air.

[0043] Figure 5 shows a plan view of another example of a high-humidity refrigerated storage system of the present invention that employs a positive pressure system. In this example, a penetration is provided in the storage cabinet's insulation panel 4 near the cooler 2, and an outside air intake fan 24 is installed. The intake air volume of this outside air intake fan is set smaller than the suction volume of the cooler fan 16 and is selected according to the level of positive pressure. An outside air intake pipe 22 is provided on the outlet side of the outside air intake fan 24, and the end of the pipe is connected to the cooler's water tank 19. This allows the introduced outside air to be blown directly into the water in the water tank 19, where it is cooled by the cooling water before forming bubbles and being released from the water surface, resulting in almost no temperature variation within the cooler. Figure 6 shows an enlarged view of the path of the outside air blown into the cooler's water tank. In this example, the storage cabinet is positively pressurized by the amount of outside air taken in by the outside air intake fan 24. However, if the positive pressure level exceeds a predetermined pressure, the air is exhausted through a differential pressure damper 23. [Explanation of symbols]

[0044] 1. Storage facility equipped with the high humidity refrigeration storage system of the present invention 2. Direct contact cooler 3. Bag-shaped duct (sock duct) 4. Storage insulation panels 11. Freezer 12 Fin coil 13...Refrigerant circulation system 14...heat exchanger 15. Sprinkler 16...Fan 17 Pump 18...Cooling water circulation system 19. Aquarium 20···Water droplet scattering prevention filter 21 Cooler outlet 22. Outside air intake piping 23. Differential pressure damper 24. Outside air intake fan

Claims

1. a direct contact cooler and a bag-shaped duct arranged within the storage facility, the direct contact cooler comprising a cooling water circulation system including a sprinkler, a water tank and a pump, a refrigerant circulation system that supplies refrigerant from a refrigerator to a fin coil, a heat exchanger, a fan and a filter to prevent water droplets from scattering, the air inside the storage facility drawn in by the fan comes into direct contact with the cooling water in the fin coil, the heat exchanger and the sprinkler to be cooled and humidified, and then passes through the filter to be sent to the bag-shaped duct, and the cooled and humidified air from the bag-shaped duct is uniformly supplied into the storage facility, the high humidity cooling storage system characterized in that an outside air intake fan is installed in the insulation panel of the storage facility, and an outside air intake piping is installed from the outlet side of the outside air intake fan to the water tank of the direct contact cooler.

2. 2. The high humidity refrigerated storage system according to claim 1, wherein the bag-shaped duct is made of a nonwoven fabric.

3. The high humidity cooling storage system of claim 1, wherein the filler filled inside the heat exchanger is made of multiple stages of regular resin filler, which are rotated 90 degrees relative to the previous stage and are designed to distribute water dripped onto one point in a straight line in a predetermined direction.

4. 2. The high-humidity refrigerated storage system according to claim 1, wherein the filter for preventing water droplets from scattering is made of polyvinylidene chloride resin fibers formed three-dimensionally.

5. The high humidity refrigerated storage system according to claim 1, wherein a differential pressure damper is installed in the heat insulating panel of the storage facility.

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