Apparatus for preserving fruits and vegetables, and method for preserving fruits and vegetables using said apparatus

Abstract

To provide a reefer container which has high cooling efficiency, low running costs and is easy to maintain. [Solution] The reefer container 1 comprises a container body 2 for storing and preserving fruits and vegetables, a cooling device 3 for cooling the inside of the container body 2, a water recovery means 4 for recovering water condensed inside the container body 2, and a curing unit 5 for curing the contents stored inside the container body 2. The cooling device 3 is configured to cool the inside of the container body 2 by passing sucked-up air from bottom to top through a heat exchange member 10 that stores cooled moisture to turn it into low-temperature, high-humidity air, and by allowing the low-temperature, high-humidity air to flow downward from top to bottom.

Description

[Technical field]

[0001] The present invention relates to a reefer container (cooling container) for containing and cooling and preserving fruits and vegetables, flowers, etc., and a method for preserving fruits and vegetables (in particular, root vegetables such as sweet potatoes and radishes, leafy stem vegetables such as onions and cabbage, and fruit vegetables such as pumpkins and cucumbers) using the reefer container. [Background technology]

[0002] Conventionally, refrigerators that cool and store fruit and vegetables using a heat exchanger in the refrigerator and circulate the air inside have been widely used, but when the temperature of the air inside the refrigerator drops, the amount of saturated water vapor in the air decreases, which can cause the moisture in the fruit and vegetables to evaporate, causing the fruit and vegetables to lose weight or even to lose their freshness. For this reason, as shown in Patent Document 1, a cooling container has been developed that is configured to turn air sucked from below into the cooling chamber of the cooling device into low-temperature, high-humidity air (air containing water vapor) by moving the air around a heat exchanger that stores cooled water when moving the air upward, and to circulate the low-temperature, high-humidity air. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3199521 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional cooling containers such as the one in Patent Document 1, when low-temperature, high-humidity air circulates through the storage space containing the fruits and vegetables, it condenses and falls to the bottom of the storage space, so water must be supplied to the heat exchanger from outside, resulting in high running costs. In addition, the condensed water that accumulates at the bottom of the storage space after the fruits and vegetables are cooled may lead to the proliferation of bacteria if the water is not removed periodically. Furthermore, as the operating time increases, calcium ions, magnesium ions, etc. contained in the water used precipitate and adhere to the heat exchanger, reducing the heat exchange efficiency and making it impossible to obtain the specified temperature.

[0005] The object of the present invention is to provide a reefer container (cooling container) that solves the above-mentioned problems of cooling containers, has high cooling efficiency, low running costs, and is easy to maintain, and to provide a method for preserving fruits and vegetables (particularly root vegetables, leafy vegetables, and fruit vegetables) that can maintain their freshness at a high level by using such a reefer container. [Means for solving the problem]

[0006] The present invention, as described in claim 1, is a movable container having a hollow container body covered with a heat insulating material and a cooling device for cooling the inside of the container body. Fruit and vegetable preservation equipment The cooling device comprises: The system includes a water storage tank capable of storing water, a chiller unit for cooling the water stored in the water storage tank, and a porous structure that functions as a heat exchanger and is made by stacking and joining a plurality of corrugated slate-like plate members made of synthetic resin, Inside the container body, The moisture cooled by the chiller unit is allowed to fall downward from the upper surface of the porous structure, so that the cooled moisture flows down into the interior of the porous structure. , sucked up air The above porous structure Inside The low-temperature, humid air is passed from the bottom to the top of the container body to become low-temperature, humid air, which is then allowed to flow downward to cool the inside of the container body. At the same time, moisture that has condensed inside the container body is collected and filtered, and then the low-temperature, humid air is cooled by passing the low-temperature, humid air from the bottom to the top of the container body. Collect in the water tank Water recovery means are provided. There are It is characterized by the above.

[0007] The invention described in claim 2 is characterized in that, in the invention described in claim 1, a curing unit is provided for heating the water stored in the porous structure.

[0008] The invention described in claim 3 is characterized in that, in the invention described in claim 1, the water recovery means is provided with a filter consisting of a structure in which a large number of bent fibers made of synthetic resin are bonded together in a scattered manner.

[0009] The invention described in claim 4 is the same as the invention described in claim 2 or 3. Fruit and vegetable preservation equipment The method for preserving sweet potatoes is characterized in that the inside of the container body containing the sweet potatoes is cured for 48 hours or more in an atmosphere of 30 to 40°C and 85 to 99% RH using a refrigerant, and then cooled and maintained in an atmosphere of 12 to 16°C and 85 to 99% RH. Note that a curing time of 96 hours or less is preferable because it is possible to reduce the cost required for preservation, and similarly, a cooling and maintaining time of 168 hours or more is preferable because it is possible to cause saccharification of the starch contained in the sweet potatoes, thereby improving the sweetness and flavor.

[0010] The invention described in claim 5 is the invention described in claim 4, Fruit and vegetable preservation equipment The sweet potatoes are washed within 96 hours after harvest before being placed in the container. The soil attached to the sweet potatoes at the time of harvest may contain bacteria, and during harvesting, the bacteria may invade the sweet potatoes through wounds before the cork layer is formed by curing, resulting in a deterioration in the quality of the sweet potatoes. In order to prevent such a situation, Fruit and vegetable preservation equipment It is preferable that the sweet potatoes be washed within 96 hours after harvest before being placed in the container. In addition, if a large amount of soil or the like is attached to the sweet potatoes, it reduces the filtration efficiency during water recovery, so it is preferable to remove the soil by washing in advance. Effect of the Invention

[0011] The method according to claim 1 Fruit and vegetable preservation equipmentThis system cools the inside of the container body as low-temperature water vapor, then collects the condensed water and reuses it as cooling water, so it has high cooling efficiency and can keep running costs low. In addition, since condensed water does not accumulate at the bottom of the part that holds the fruits and vegetables, maintenance is easy.

[0012] The method according to claim 2 Fruit and vegetable preservation equipment Since the device is equipped with a curing unit for heating the water stored in the porous structure that functions as a heat exchanger, it can also be suitably used for preserving fruits and vegetables (root vegetables, leafy vegetables, fruit vegetables, etc.) whose freshness can be maintained at a high level by curing treatment.

[0013] The method according to claim 3 Fruit and vegetable preservation equipment The water recovery means is equipped with a filter consisting of a structure in which a large number of bent fibers made of polyvinylidene chloride are bonded together in a scattered pattern, and when recovering water that has condensed inside the container body, it can effectively filter out mud and foreign matter, making it possible to perform its cooling function for a long period of time without damage.

[0014] The method according to claim 4 Fruit and vegetable preservation equipment According to the method for preserving sweet potatoes using the above, it is possible to maintain the freshness of sweet potatoes at a low cost and improve their sweetness and flavor.

[0015] The method according to claim 5 Fruit and vegetable preservation equipment According to the method for preserving sweet potatoes using the above, the curing effect of the sweet potatoes can be further improved, the freshness of the sweet potatoes can be maintained at a high level, and the efficiency of water recovery can be improved. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram (conceptual diagram) showing the inside of a reefer container. [Diagram 2] FIG. 2 is an explanatory diagram (conceptual diagram) showing an installation portion of a cooling device. [Diagram 3]FIG. 1 is an explanatory diagram showing a heat exchange member (a is a front view, b is a plan view, c is a cross-sectional view taken along line AA in b, d is a cross-sectional view taken along line BB in b, and e is an enlarged view of part α in c). [Figure 4] FIG. 1 is an explanatory diagram (conceptual diagram) showing the operation of a reefer container. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of a reefer container and a method for preserving fruits and vegetables (sweet potatoes) using the reefer container according to the present invention will be described in detail with reference to the drawings.

[0018] <Reefer container structure> 1 is a conceptual diagram showing the inside of a reefer container, in which the reefer container 1 comprises a container body 2 for storing and preserving fruits and vegetables, a cooling device 3 for cooling the inside of the container body 2, a water recovery means 4 for recovering water condensed inside the container body 2, and a curing unit 5 for curing the contents stored inside the container body 2. The cooling device 3 and the curing unit 5 are connected to a control device (not shown) so that their operation can be controlled by the control device.

[0019] The container body 2 is formed of metal in a hollow rectangular parallelepiped shape, and the inside surface is covered with a heat insulating material. Inside the container body 2, a storage section (storage space) 6 capable of storing fruits and vegetables F, F, etc. is formed, and a storage shelf 7 for placing the fruits and vegetables F, F, etc. is installed. The shelf board (bottom board) of the storage shelf 7 is in a mesh shape. Furthermore, at one end in the longitudinal direction of the container body 2 (the left end in FIG. 1), a door member (not shown) for carrying in and carrying out the fruits and vegetables F, F, etc. is provided so as to be able to open like a double door. At the other end in the longitudinal direction of the container body 2 (the right end in FIG. 1), a cooling device 3 is installed (a part of the container body 2 is partitioned as the cooling device 3).

[0020] In addition, a temperature / humidity sensor 23 is provided in the storage section 6 of the container body 2, which detects the temperature and humidity inside the storage section 6 and feeds back this data to a control device (not shown), making it possible to precisely control the temperature and humidity inside the storage section 6 to be at preset values.

[0021] 2 shows an installation portion of the cooling device 3, which is composed of a water tank 8 capable of storing cooling water, a chiller unit 9 for cooling the water stored in the water tank 8, a heat exchange member 10 which is a porous structure acting as a heat exchanger, a discharge pipe 11 for causing the water stored in the water tank 8 to fall evenly and uniformly into the heat exchange member 10, a circulation pump 12 for drawing the water stored in the water tank 8 to the drain pipe 11, a first water lift pipe 13 connecting the water tank 8 and the discharge pipe 11, a circulation fan 14 for drawing the air in the storage section 6 into the cooling device 3, etc. The cooling device 3 is separated from the storage section 6 by a case 15, and a discharge window 16 and a suction window 17 are formed in the upper and lower parts of the case 15, respectively.

[0022] Meanwhile, the chiller unit 9 includes a heat exchanger, a compressor, and a pressure reducer, and is capable of cooling the stored water in the water storage tank 8 by heat exchange using a refrigerant. In addition, the chiller unit 9 is capable of controlling the cooling temperature of the stored water in the water storage tank 8 by changing the compression ratio of the refrigerant by the compressor and the pressure reducer by a control device (not shown). Also, the discharge pipe 16 has a large number of water spray holes, and is capable of causing the water drawn up through the first water lift pipe 13 to fall (spray) evenly and uniformly onto the upper surface of the heat exchange member 10.

[0023] 3 shows a heat exchange member, and the heat exchange member 10 has a porous structure 10a housed inside a case 10b. The porous structure 10a is made by stacking a predetermined number of rectangular plate members 10p, 10p, etc., which are made by pressing a plate material made of synthetic resin (polypropylene) having a predetermined thickness (about 1.5 mm) into a predetermined shape, and joining (gluing or fusing) them in a scattered manner at predetermined positions.

[0024] Each plate member 10p, 10p... has a shape (i.e., a corrugated slate shape) in the middle part in the height direction (excluding the parts of a constant width (about 100 mm) at the upper and lower edges) in which linear mountain folds of a constant width (mountain folds with a cross section perpendicular to the longitudinal direction that is approximately U-shaped) inclined to form a predetermined angle (about 45°) with respect to the vertical direction and linear valley folds of approximately the same width (valley folds with a cross section perpendicular to the longitudinal direction that is approximately U-shaped) are continuously arranged in the plane. Also, in the parts of a constant width (about 100 mm) at the upper and lower edges, the mountain folds of the constant width and the valley folds of approximately the same width are curved and arranged vertically. The ridge lines (fold lines) L1, L1... of the mountain folds and the ridge lines L2, L2... of the valley folds are arranged in parallel at equal intervals. In addition, in each mountain fold and each valley fold, countless grooves V, V·· are provided at equal intervals, perpendicular to the longitudinal direction and having a predetermined depth (a depth sufficiently shallow compared to the thickness of the plate member 10p = approximately 0.5 mm).

[0025] In the structure 10a, a predetermined number of these plate members 10p, 10p... are stacked alternately in reverse order so that the ridge lines L1, L1... of the mountain fold portion in the middle and the ridge lines L2, L2... of the valley fold portion are perpendicular to each other (stacked so that the ridge lines L1, L1... and ridge lines L2, L2... of adjacent plate members 10p, 10p are perpendicular to each other), and are assembled together by joining them in a scattered manner at predetermined positions.

[0026] On the other hand, the water recovery means 4 is composed of a tray 18 laid so as to cover the bottom surface of the storage section 6, a water lifting pump 19 for lifting (returning) the condensed water stored in the tray 18 to the water storage tank 8, a second water lifting pipe 20 connecting the tray 18 and the water storage tank 8, and a filter 21 for filtering the condensed water stored in the tray 18 when it is lifted to the water storage tank 8. The filter 21 is made of numerous bent fibers (average thickness = about 0.5 mm) made of synthetic resin (polyvinylidene chloride) bonded together in a scattered pattern, and has a thickness of about 50 mm.

[0027] Similarly to the chiller unit 9, the curing unit 5 is equipped with a heat exchanger, a heater, a compressor, and a pressure reducer, and is capable of heating the water stored in the water storage tank 8 by heat exchange using a refrigerant. In addition, the curing unit 5 is capable of controlling the temperature of the water stored in the water storage tank 8 by changing the compression ratio of the refrigerant by the compressor and the decompression ratio of the refrigerant by the decompressor using a control device (not shown). The water stored in the water storage tank 8 can also be heated by utilizing the heater.

[0028] In addition, a storage information management device 22 equipped with a storage means and an information transmission means is attached to the outside of the container body 2, and is capable of storing information such as the type, place of origin, quantity, storage period, delivery destination, storage history regarding storage period and atmosphere of the fruits and vegetables etc. stored in the container body 2, and transmitting this information based on commands from outside.

[0029] <Reefer container operation details> 4 shows the operation of the reefer container 1 configured as described above, and the reefer container 1 can accommodate and store fruits and vegetables F, F, etc., flowers, etc., in the container body 2, by placing them on the shelves of the storage shelves 7. When the cooling device 3 is operated with fruits and vegetables F, F, etc. accommodated and stored in the container body 2 in this manner, the air inside is sucked up by the circulation fan 14 at the bottom of the cooling device 3, flows into the inside of the cooling device 3 (cooling chamber) through the suction window 17, and becomes an ascending air current that passes through the inside of the heat exchange member 10.

[0030] On the other hand, when the cooling device 3 is driven, the stored water in the water storage tank 8 is cooled by the chiller unit 9, and the cooling water is raised by the circulation pump 12 through the first lift pipe 13 to the upper drain pipe 11. The cooling water raised to the drain pipe 11 is then sprayed at a constant pressure from a large number of spray holes drilled in the drain pipe 11, falls onto the upper surface of the heat exchange member 10, and flows down inside the heat exchange member 10 (inside the porous structure 10a).

[0031] Then, inside the heat exchange member 10, heat is exchanged between the air rising from below and the cooling water flowing down from above, and the rising air is cooled while low-temperature water vapor is generated by the evaporated cooling water. Then, the low-temperature air and water vapor are blown out from the upper exhaust window 16 to the top of the storage section 6 by the airflow of the circulation fan 14. The entire storage section 6 is efficiently cooled by the low-temperature air and water vapor blown out from the top in this manner.

[0032] Furthermore, the low-temperature air and water vapor sprayed out to the top of storage section 6 flow downward and cool the fruits and vegetables F, F... placed on storage shelves 7 (i.e., heat exchange occurs between the fruits and vegetables F, F...). The water vapor that has cooled the fruits and vegetables F, F... condenses as its temperature rises and falls to the bottom of storage shelves 7. The condensed water that falls in this manner is collected in tray 18 installed below storage shelves 7. Note that when the water vapor that has cooled the fruits and vegetables F, F... condenses, dirt and other particles adhering to the fruits and vegetables F, F... mix with the condensed water and fall into tray 18.

[0033] The water (condensed water) stored in the tray 18 as described above is lifted up through a second lift pipe 20 by a water pump 19 installed at one end (the right end in FIG. 1) of the tray 18, and is discharged (returned) into the water storage tank 8. When the water stored in the tray 18 is lifted up by the water pump 19, the water is filtered by a filter 21 installed below the water pump 19, and mud and foreign matter in the water are removed.

[0034] On the other hand, in the reefer container 1, the fruits and vegetables F, F, etc. contained in the container body 2 can be cured for the purpose of preventing the proliferation of microorganisms. For example, when curing sweet potatoes, the curing unit 5 is operated to heat the water stored in the water storage tank 8 instead of driving the chiller unit 9 of the cooling device 3. When the water stored in the water storage tank 8 is heated in this way, the hot water is raised to the upper drain pipe 11 by the circulation pump 12. The hot water raised to the drain pipe 11 is sprayed from the water spray holes drilled in the drain pipe 11, falls on the upper surface of the heat exchange member 10, and flows down inside the heat exchange member 10 (inside the porous structure 10a). When the water stored in the water storage tank 8 is heated, water vapor is generated by the evaporated hot water.

[0035] Then, inside the heat exchange member 10, heat exchange takes place between the air rising from below and the hot water flowing down from above, and the rising air is heated. Then, the heated air and the warm water vapor evaporated from the water storage tank 8 are blown out from the upper exhaust window 16 to the top of the storage section 6 by the airflow of the circulation fan 14. The entire storage section 6 is heated by the warm air and water vapor blown out from the top in this way. Note that, if condensation water from the ceiling of the storage section drips onto the sweet potatoes during the curing process, it is possible to reverse the rotation of the circulation fan to change the flow of warm air inside the storage section from the bottom to the top.

[0036] <Sweet potato preservation test> Using the reefer container 1 described above, a freshness preservation experiment on sweet potatoes was conducted. That is, 500 g of sweet potatoes were placed on the storage shelf 7 of the container body 2 of the reefer container 1, and the inside of the container body 2 was kept in an atmosphere of 33°C and 95% RH for 72 hours, and then in an atmosphere of 14°C and 90% RH for 168 hours. The freshness of the sweet potatoes thus stored in the reefer container 1 was compared with that of sweet potatoes stored in an atmosphere of 25°C and 65% RH for 240 hours in terms of mold growth, wilting, odor, and sweetness. As a result, it was recognized that the sweet potatoes stored in the reefer container 1 had better freshness in terms of both wilting and odor.

[0037] <Effects of Reefer Container> As described above, the reefer container 1 cools the inside of the container body 2 by passing the air sucked up inside the container body 2 from bottom to top through the heat exchange member (porous structure) 10 that stores cooled moisture, and by causing the low-temperature, humid air to flow downward from top to bottom, and is also provided with a water recovery means 4 that collects moisture condensed inside the container body 2, filters the moisture, and then uses it as moisture to be stored in the heat exchange member (porous structure) 10. Therefore, the reefer container 1 has high cooling efficiency and can keep running costs low. In addition, the reefer container 1 is easy to maintain because condensed water does not accumulate at the bottom of the part that stores fruits and vegetables.

[0038] In addition, the reefer container 1 is provided with a curing unit 5 for heating the water stored in the heat exchange member (porous structure) 10, so it can be suitably used for preserving fruits and vegetables such as root vegetables, leafy vegetables, and fruit vegetables (especially sweet potatoes, onions, and pumpkins) whose freshness can be maintained at a high level by curing treatment.

[0039] Furthermore, the reefer container 1 is equipped with a filter 21, in which the water recovery means 4 is made of a structure in which a large number of bent fibers made of synthetic resin are bonded together in a scattered pattern, and since it can effectively filter out mud and foreign matter when recovering water condensed inside the container body 2, it can perform its cooling function for a long period of time without being damaged.

[0040] In addition, since the reefer container 1 has a heat exchange member (porous structure) 10 having a porous structure of a special shape as described above, it has good heat conversion efficiency and can cool fruits and vegetables very efficiently.

[0041] <Example of reefer container modification> The reefer container according to the present invention is not limited to the above-mentioned embodiment, and the materials, sizes, shapes, structures, etc. of the container body, cooling device, water recovery means, curing unit, heat exchange member, filter, etc. can be appropriately changed as necessary without departing from the spirit of the present invention, and a water supply tank, etc. can be installed when more water is consumed than is recovered. Also, when storing fruits and vegetables whose freshness deteriorates due to carbon dioxide damage, it is possible to reduce the carbon dioxide concentration in the storage section by separately installing a device for removing carbon dioxide dissolved in low-temperature, humid air.

[0042] For example, the reefer container according to the present invention is not limited to one in which the chiller unit and the curing unit 5 are provided separately as in the above embodiment, but may be one in which the chiller unit and the curing unit are integrated. The reefer container according to the present invention is not limited to one that is stationary as in the above embodiment, but may be one that is transportable by a trailer or the like. Furthermore, the porous structure of the cooling device is not limited to one that is formed by a single porous structure as in the above embodiment, but may be one in which multiple types of porous structures are stacked one above the other. On the other hand, the filter of the water recovery means is not limited to one in which a large number of bent fibers made of synthetic resin are bonded together in a scattered manner, but may be changed to one made of woven fabric or nonwoven fabric, and may be used in combination with other filtering devices such as a sand filtering device.

[0043] Furthermore, the porous structure used as the heat exchange member is not limited to the above embodiment in which a predetermined number of rectangular plate members each folded so that the mountain folds and valley folds are continuous are stacked so that the fold lines intersect at right angles and then joined in a scattered manner at predetermined positions, but can also be changed to a structure in which a plurality of corrugated sheets (such as those having a sine wave-shaped cross section or a cross section having a shape of a continuous trapezoid and inverted trapezoid) are stacked and joined in the same direction (glued or fused), or a structure in which a plurality of corrugated sheets are stacked and joined so that the directions of their grooves intersect at a predetermined angle (10 to 80°) in a staggered manner. [Industrial Applicability]

[0044] INDUSTRIAL APPLICABILITY The reefer container according to the present invention has the excellent effects as described above and can therefore be suitably used as a device for storing and preserving fruits and vegetables, flowers, and the like. [Explanation of symbols]

[0045] 1. Reefer container 2. Container body 3...Cooling device 4. Water recovery means 5. Curing unit 6. Storage section 7. Storage shelf 8. Water tank 9. Chiller unit 10. Heat exchange material (porous structure) 10a·Porous structure 10b··Case 10p...Plate member 11...Drain pipe 12. Circulation pump 13...First pumping pipe 14. Circulation fan 15··Case 16. Discharge window 17. Intake window 18 ··Tray 19. Water pump 20...Second pumping pipe 21 Filter 22... Storage information management device 23 Temperature and humidity sensor

Claims

1. A movable fruit and vegetable storage device comprising a hollow container body covered with a heat insulating material and a cooling device for cooling the inside of the container body, The cooling device comprises: The system includes a water storage tank capable of storing water, a chiller unit for cooling the water stored in the water storage tank, and a porous structure that functions as a heat exchanger and is made by stacking and joining a plurality of corrugated slate-like plate members made of synthetic resin, In the container body, the moisture cooled by the chiller unit is dropped downward from the upper surface of the porous structure, so that the cooled moisture flows down inside the porous structure, while the sucked-up air is passed from the bottom to the top inside the porous structure to become low-temperature, humid air, which is then allowed to flow downward from the top to the bottom, thereby cooling the inside of the container body; A fruit and vegetable preservation device comprising a water recovery means for collecting water condensed inside the container body, filtering the water, and then recovering the water in the water storage tank.

2. 2. The apparatus for preserving fruits and vegetables according to claim 1, further comprising a curing unit for heating the water stored in the porous structure.

3. 2. The fruit and vegetable preservation device according to claim 1, wherein the water recovery means is provided with a filter having a structure in which a large number of bent synthetic resin fibers are bonded together in a scattered manner.

4. Using the fruit and vegetable preservation device according to claim 2 or 3, The inside of the container body containing the sweet potatoes is cured in an atmosphere of 30 to 40 ° C. and 85 to 99% RH for 48 hours or more, and then cooled and maintained in an atmosphere of 12 to 16 ° C. and 85 to 99% RH. A method for preserving sweet potatoes.

5. The method for preserving sweet potatoes according to claim 4, wherein the sweet potatoes before storage are washed within 96 hours after harvest.

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