Refrigerator with Drying Function

Abstract

When drying food ingredients in a refrigerator, it is possible to dry them easily, inexpensively, efficiently, and quickly while maintaining their quality and without the transfer of odors to other food ingredients. 【Solution means】 In a drying treatment chamber cooled through a cold air shielding wall by cold air circulation wind heat-exchanged by a cooler in the freezing temperature range, a moisture-permeable film multilayer body through which only water vapor and moisture can permeate is provided as a partition surface on a part of the upper ceiling shielding wall, and water vapor and moisture from the food ingredients to be dried heated by heating means on the lower bottom surface are actively condensed and captured on the moisture-permeable film surface, the moisture-permeable film automatically increases the moisture permeability, and water vapor and moisture are appropriately released to the outside of the drying treatment chamber.

Description

Technical Field

[0001] The present invention relates to a drying treatment chamber for making dried fruits, dried vegetables, dried foods, etc. at home, or a refrigerator-freezer with a drying function equipped with a drying treatment container or the like.

Background Art

[0002] Conventionally, as techniques for producing dried foods, the sun-drying method, the cold-air drying method, the heat-drying method, and the vacuum freeze-drying method have become mainstream. However, each has its own advantages and disadvantages, and the drying method is properly selected depending on the type of food, its use, and the processing amount.

[0003] The sun-drying method is a drying method that has been around since ancient times as a method for making dried radishes and dried persimmons. It is a method of drying over time using natural environments such as sunlight, temperature, humidity, wind, etc. It does not require a special device for processing and can dry a large amount of foodstuffs relatively inexpensively. However, it takes a long time to dry, and there are major problems in that the quality fluctuates due to changes in light, temperature, humidity, wind, etc. in the natural environment and it lacks stability.

[0004] The cold-air drying method is a drying method widely used for dried fresh products. As shown in Patent Document 1, cooled and dry air is circulated to evaporate moisture. It is carried out in a relatively low-temperature space of 5°C to 35°C, preventing rapid deterioration of food, not being affected by the weather like sun-drying, and being relatively inexpensive compared to other drying methods. However, the problem of a long drying treatment time remains. Without an independent cooling system and drying space for drying, the odor of the food to be dried spreads in the storage, so it is difficult to share with a household refrigerator-freezer where foodstuffs are mixed. If it becomes an independent household cold-air drying storage, the amount of food consumed by a household in a day is small, and the equipment cost becomes high, making it uneconomical in terms of price.

[0005] The heat drying method is generally used for drying vegetable and fruit ingredients. It involves exposing the ingredients to be dried in a space heated by an electric heater or the like, and forcibly evaporating and drying the moisture in the ingredients with heat, enabling drying and finishing in a short time. Although the equipment cost is relatively low, it requires a large amount of energy for heating, and there are problems such as decomposition of nutrients in the ingredients due to heat, oxidative deterioration of the ingredient structure and components, color change, and challenges in maintaining the initial quality.

[0006] The vacuum freeze-drying method, also known as freeze-drying, is a drying method that utilizes sublimation, in which rapidly frozen ingredients are gently heated under high vacuum conditions to change from ice to water vapor. It is commonly used in instant foods. It can dry ingredients with relatively few component changes in the ingredients, maintain the quality of the food, and enable long-term preservation in a relatively short time. Furthermore, since the frozen ingredients are dried under reduced pressure, many pores remain, and the dried product has the merit of being easily restored when water or hot water is poured on it. However, because the dedicated mechanical equipment for creating a vacuum is expensive, it is usually used for industrial production of drying large quantities of food. In small-scale production, the amortization cost of the equipment has an impact, and the processing cost becomes high. Moreover, it is not suitable as a household device.

[0007] Also, as a recent freeze-drying technology, an atmospheric pressure freeze-drying method without reducing pressure or creating a vacuum has been proposed. Non-Patent Document 1 introduces the possibility of atmospheric pressure freeze-drying as a food manufacturing technology in recent years. The main content is to freeze the ingredients to be freeze-dried, and then send and sublimate-dry the surface of the ingredients to be freeze-dried while controlling the dry air at a temperature slightly higher than the product temperature. Among them, the sublimation drying due to the water vapor partial pressure difference is close to the sublimation rate under reduced pressure, eliminating the equipment cost for vacuum reduction and the power consumption for reducing pressure, and the processing cost becomes low. Furthermore, depending on the ingredients and the degree of drying, it is described that the texture becomes better and more delicious.

[0008] However, whether it is the vacuum freeze-drying method or the atmospheric freeze-drying method, although the decomposition of food components and nutrients can be suppressed in the low-temperature range of freezing, the tissues of fresh vegetables and the like are damaged to a certain extent by freezing, and there is also damage to pectin that connects cells. After thawing, the texture of vegetables and the like significantly softens and changes. In addition, although drying by freezing suppresses shrinkage, many pores and the like remain where moisture has escaped, and when dry air enters there, oxidation easily progresses due to reaction with oxygen. Therefore, it is difficult to say that the quality of dried food by the freeze-drying method is always stable. In addition, drying by sublimation basically cannot create a large water vapor pressure difference due to the low temperature, and the problem of long processing time remains.

[0009] That is, in order to dry, like sun drying or cold air drying, a food material with a large amount of moisture is exposed to a natural environment or cold air with low humidity, and dried using the humidity difference that creates a water vapor pressure difference, or by heating the food material, the absolute humidity at the food material interface is made higher than the absolute humidity of the outside air environment to increase the evaporation rate and dry it, or by reducing the pressure of the installation environment of the food material to a reduced pressure or vacuum to facilitate the evaporation and sublimation of moisture in the food material. These are all grouped into drying methods. Among them, there is also a method of extracting moisture using osmotic pressure, but there is a problem that the taste of the material changes with the moisture absorbent in contact. As a normal drying process, it can generally be said that a combination of methods for controlling the humidity difference, temperature difference, and pressure difference is used for drying.

[0010] In particular, as a food drying device for home use, the heating drying method in which a heat source or hot air directly intervenes in the food is the simplest and quickest way to make dried food, so many household heating-type food dryers have been commercialized. However, when heating at a high temperature of 35°C or higher, the oxidative deterioration of the food is severe, which not only promotes discoloration and decomposition of nutrients but also causes a major problem of food spoilage by microorganisms, and improvement measures in this regard are desired.

[0011] Therefore, various methods have been tried and proposed to dry the food material to be dried in the refrigerator by applying the environment where the moisture in the refrigerator is removed and the humidity is reduced by utilizing the dehumidifying function of the cooler in the refrigerator-freezer, that is, the evaporator in the refrigeration system.

[0012] For example, as a drying chamber mounted in a refrigerator, Patent Document 2 discloses a drying chamber having a cooling plate in contact with cold air at the upper part, a heating device at the lower part, and most of it covered with a heat insulating material. The drying chamber is provided as a part of the path through which the cold air in the refrigerator circulates. A refrigerator with a drying chamber is introduced, in which the dew moisture in the drying chamber condensed by the cooling plate is made to communicate the inside and outside of the drying chamber through a moisture absorbing material that absorbs water and the passage of cold air.

[0013] That is, by removing the moisture in the drying chamber by condensing and dew-forming it on the surface of the cooling plate, the humidity in the drying chamber is reduced. The moisture condensed and dew-formed on the cooling plate is absorbed by a moisture absorbing material that communicates the inside of the drying chamber with the passage side of the cold air outside, and the absorbed moisture is automatically discharged to the path through which the cold air in the refrigerator with low humidity circulates and can be dried. Therefore, the dehumidification in the drying chamber can be achieved with a simple structure. Since it is in a semi-closed state, the odor of the dried food does not transfer from the drying chamber to other compartments in the refrigerator, and the food can be stored in a dried state.

[0014] Furthermore, Patent Document 3 discloses a refrigerator with a drying chamber that evaporates the refrigerant compressed by a compressor in an evaporation section to cool the surrounding air and circulates the cooled air. The refrigerator forms a part of the wall of the drying chamber, and includes a cooling plate that cools and condenses the moisture in the drying chamber, a moisture absorbing member that is provided so that one side is in contact with the atmosphere in the drying chamber and the other side is in contact with the atmosphere outside the drying chamber, has moisture permeability, and evaporates the moisture condensed by the cooling plate to the outside of the drying chamber, a heating means for heating the inside of the drying chamber, and a heating control means for controlling the heating of the heating means according to the temperature of the cooled air, or a feed control means for controlling the feed of cold air. A refrigerator with a drying chamber is introduced.

[0015] That is, as an additional effect to Patent Document 2, since a heating control means for controlling the heating of the heating means according to the temperature of the cold air, or a feed control means for controlling the feed of the cold air is provided, the temperature of the drying chamber can be kept almost constant, and by controlling the feed of the cold air to the vicinity of the drying chamber, the temperature in the drying chamber can be kept more constant.

[0016] Further, Patent Document 4 discloses a refrigerator having a drying chamber installed in a refrigerating chamber, which includes a damper for the drying chamber that adjusts the air volume of the cold air forcibly blown by a blower fan, a humidity sensor that detects the humidity in the drying chamber, and a heater. The refrigerating chamber and the drying chamber are cooled by the cold air forcibly blown by the blower fan, and the drying chamber is controlled to a predetermined humidity by the humidity sensor, the damper for the drying chamber, and the heater.

[0017] That is, by attaching a humidity sensor in the drying chamber, a drying chamber can be obtained that can maintain a certain low humidity by the cold air forcibly blown by the blower fan and the heater, and drying with stable temperature and humidity enables drying with less deterioration of food components.

[0018] Further, Patent Document 5 discloses a refrigerator having a freezing chamber and a refrigerating chamber, which is provided in the refrigerating chamber with a drying chamber equipped with a heat source for storing the food to be dried, and a steam condenser chamber equipped with a steam condenser, which is integrated with or connected to the drying chamber. A vacuum pump for evacuating the drying chamber and the steam condenser chamber to the outside of the refrigerator is provided. In parallel with the refrigeration cycle for cooling the freezing chamber and the refrigerating chamber, a vacuum drying cycle passing through the steam condenser is provided, and a switch for switching between a refrigeration mode and a vacuum drying mode is provided. When producing vacuum-dried food, the food to be dried is stored in the drying chamber, and by switching to the vacuum drying mode with the switch, the refrigerant is caused to flow into the vacuum drying cycle, the vacuum pump is driven, and the ice portion of the food to be dried is sublimated by the heat source, and the water vapor generated by this sublimation is removed by the steam condenser. A refrigerator with a vacuum drying function is introduced.

[0019] That is, it is a device in which a vacuum freeze-drying device is attached to a household refrigerator, and it is a process of drying by sublimation while heating the frozen product. It can be said to be an ideal drying method if it can be put into practical use in maintaining the quality of food.

Prior Art Documents

Non-Patent Documents

[0020]

Non-Patent Document 1

Patent Documents

[0021]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0022] However, in the drying treatment chamber mounted on the refrigerator disclosed in Patent Document 2, the moisture condensed on the cooling plate is absorbed by the moisture absorbent that communicates the inside of the drying chamber with the cold air passage side outside. The absorbed moisture can be automatically discharged to the path where the cold air in the refrigerator with low humidity circulates for drying. However, if the amount of the food material to be dried is large and the amount of condensation on the cooling plate is large, the moisture absorbent cannot process all of it, and a large amount of water will remain inside the drying chamber. Also, if the cooling plate area is reduced and the amount of the moisture absorbent is increased, the temperature inside the drying chamber will rise, so control of the heating device is required, and there is a problem that the drying time becomes long. The material used as the moisture absorbent is formed by a bundle of fibers such as synthetic fiber and cotton, or a hydrophilic resin or a sponge-like substance. Due to capillary action, moisture can freely penetrate, but it has a high heat insulation property and is a material through which cold air and warm air cannot flow. Therefore, outside the drying chamber where the cold air in the refrigerator circulates, it may be below 0°C, and the moisture absorbent may freeze, resulting in a problem that the movement of moisture becomes impossible.

[0023] Also, even if heating control means for controlling heating according to the temperature of cold air or feed control means are provided as in the drying treatment chamber disclosed in Patent Document 3, and the temperature in the drying chamber can be kept constant, the amount of moisture discharged varies depending on the amount of the foodstuff to be dried stored in the drying chamber. Thus, when the amount of the foodstuff to be dried is large, the amount of moisture discharged increases, causing water to accumulate in the drying chamber. When the amount of the foodstuff to be dried is small, the influence of the cooling plate becomes significant, and an excessive amount of heat is required for the cooling plate and the heating of the drying treatment chamber by the heating control means.

[0024] Also, the material used as the moisture absorbent is the same as that in Patent Document 2, and is formed of a bundle of fibers such as synthetic fiber or cotton, or a hydrophilic resin or sponge-like substance. Moisture can freely penetrate due to capillary action between the fibers, but the material has high heat insulation and does not allow the circulation of cold air or warm air. Therefore, outside the drying chamber where the cold air in the refrigerator circulates, the temperature may be below 0 °C, causing the moisture absorbent to freeze and leaving the problem that moisture movement becomes impossible.

[0025] Also, this is a problem common to Patent Document 2 and Patent Document 3. Even if the heating means heats the foodstuff to be dried to 30 °C, the humidity condition in the drying chamber is at the water vapor pressure with a dew point temperature of 0 °C and a relative humidity of 100%. At the same water vapor pressure, the relative humidity value is still quite high, and it cannot be said to be sufficient drying conditions, resulting in a longer drying time.

[0026] Also, in the drying chamber installed in the refrigerator disclosed in Patent Document 4, a humidity sensor is attached in the drying chamber, and the drying chamber can maintain a certain humidity with cold air forced by a blower fan and a heater. However, in such a fan-cooled drying chamber, since the refrigerator and the drying chamber are cooled by cold air forced by the same blower fan, the odor of the foodstuff to be dried generated in the drying chamber spreads into the refrigerator and freezer, and the transfer of odor to other foods and ice becomes a major problem.

[0027] In addition, the refrigerator-freezer with a vacuum drying function disclosed in Patent Document 5 is provided with a vacuum pump that evacuates a drying chamber equipped with a heating source and a steam condensation chamber for storing food to be dried, and sublimates the ice portion of the food to be dried by switching to the vacuum drying mode. Although it is an ideal drying method for maintaining food quality because it dries by sublimation, in order to be installed in a general household refrigerator-freezer, a vacuum pump, a mode switching device, and another condenser are required, resulting in a complex structure. There are problems with pump noise and handling when opening and closing the door of the drying chamber that is depressurized. Furthermore, drying by sublimation takes a very long time.

[0028] The present invention has been made to solve the above problems, and is equipped with a drying treatment chamber or a drying treatment container that can be inexpensively and easily attached to a general household refrigerator-freezer, and aims to provide a refrigerator-freezer with a drying function that increases the drying speed while maintaining the quality of food.

Means for Solving the Problems

[0029] Therefore, the present invention uses a moisture-permeable waterproof material that does not allow water to pass through but allows water vapor and moisture to pass through, so-called a moisture-permeable membrane, as a partition for the cold air shielding wall of the drying treatment chamber, and creates drying conditions as an optimal drying treatment chamber in the refrigerator-freezer by controlling the temperature, humidity, and the amount of water vapor moisture passing through in the drying treatment chamber. In this text, there are expressions such as water vapor, moisture, water, condensed water, and water. Water vapor and moisture indicate a moist gas state, condensed water and water indicate a liquid state, and moisture means the molecular state of water. Therefore, the moisture-permeable membrane allows water vapor and moisture to pass through, but does not allow liquid condensed water or water to pass through as it is. The permeation amount refers to the amount that permeates as it is in a gaseous state, and also includes the amount where water vapor condenses, the condensed water penetrates the moisture-permeable membrane to become water molecules, and these water molecules become water vapor again and evaporate on the opposite side.

[0030] As a typical moisture-permeable film resin material, a hydrophilic urethane-based resin film is used, which has the characteristic that the moisture permeability changes greatly with the glass transition point Tg as the boundary. That is, in the glass temperature region below the glass transition point Tg, the molecular structure becomes crystalline and densifies, while in the rubbery temperature region above the glass transition point Tg, the molecular structure relaxes and the moisture permeation increases because of this. Since repeating the temperature fluctuation up and down near the glass transition point Tg shows almost the same value of moisture permeability with good reproducibility, by designing a polymer with an appropriate moisture permeability and glass transition point Tg in the refrigeration temperature range, the characteristics of this moisture-permeable film are utilized to create optimal drying conditions in the refrigerator.

[0031] Another major property of the moisture-permeable film represented by this hydrophilic urethane-based resin film is that in the dew condensation state, the moisture-permeable film absorbs a large amount of moisture and promotes evaporation on the entire surface of the moisture-permeable film, so it has the characteristic that the moisture permeability increases significantly. Therefore, due to the temperature difference and humidity difference between the drying chamber and the refrigeration chamber, when dew condensation occurs on the inner side of the moisture-permeable film in the drying treatment chamber, the amount of moisture movement in the moisture-permeable film becomes extremely large and is discharged as vapor outside the drying treatment chamber. Therefore, the condensed dew does not drip into the drying treatment chamber, and the moisture movement into the refrigeration chamber can be smoothly carried out. This moisture-permeable film is a non-porous film. Although water molecules move within the polymer, it has no air permeability, and there is no movement of liquid water, air, odor components, etc.

[0032] In addition, a moisture-permeable film of a hydrophilic urethane-based resin film with a glass transition point Tg designed to change from the glassy region to the rubbery region in the refrigeration temperature range is laminated as a film on a base fabric of a woven or non-woven fabric of nylon or polyester, and is interposed as a partition at the interface between the inner and outer sides on the upper ceiling shielding wall of the drying treatment chamber. With heating means such as an electric heater on the lower bottom surface of the drying treatment chamber, the water vapor and moisture from the heated food to be dried are actively condensed and captured on the surface of the moisture-permeable film. A mechanism is constructed in the drying treatment chamber where the moisture-permeable film automatically increases the moisture permeability and appropriately releases moisture outside the drying treatment chamber.

[0033] This enables the creation of a sealed drying chamber, preventing the odor of the food ingredients to be dried from leaking into other parts of the refrigerator and causing odor transfer. Not only does the moisture permeability of the moisture permeable membrane change with the temperature change in the drying chamber, but also the moisture permeability becomes an appropriate amount due to the amount of moisture absorbed by condensation. By optimizing the heat insulation performance of the base materials of woven or non-woven fabrics and the cold air shielding wall, the temperature inside the drying chamber can be made uniform at a predetermined temperature, and a refrigerator-freezer with a drying function that can promote drying more quickly is provided.

[0034] That is, in order to solve the above problems, a refrigerator-freezer with a drying function according to a first aspect of the present invention is provided in a refrigerating chamber that is cooled by cold air circulation wind heat-exchanged by a cooler in a freezing temperature zone. The drying chamber that is cooled by the cold air circulation wind through a cold air shielding wall forms a sealed space surrounded by the cold air shielding wall and the like. In the sealed space, there are a breathable storage shelf such as a net-like structure on which the food ingredients to be dried can be placed, heating means such as an electric heater that heats the sealed space to a predetermined temperature from the bottom surface, and temperature detection and control means for the sealed space that controls the heating means. A part of the cold air shielding wall has an opening and closing mechanism shielding wall through which the food ingredients to be dried or the storage shelf can be taken in and out, and a humidity control window provided with a moisture permeable membrane or a moisture permeable membrane laminate that allows only water vapor and moisture to permeate as a partition surface on a part of the upper ceiling shielding wall of the drying chamber.

[0035] According to this refrigerator-freezer with a drying function, the cold air circulation wind heat-exchanged and cooled by the freezing temperature zone cooler is in an environmental state with a relatively low humidity because the moisture in the cold air circulation wind condenses or forms frost on the surface of the cooler and is removed. For example, if the freezing temperature zone in the cooler is set to -25°C and the refrigerating chamber is cooled to a refrigerating temperature zone of 5°C by the cold air circulation wind, the relative humidity in the refrigerating chamber will be about 10% according to the calculation from the Tetens formula for the saturated water vapor partial pressure.

[0036] In addition, since the drying chamber cooled through the cold air shielding wall is a sealed space with a cold air shielding wall, the odor of the food ingredients to be dried in the drying chamber will not transfer to the food or ice in other refrigerating chambers or freezing chambers during the drying process.

[0037] In addition, if an opening and closing mechanism shielding wall is provided on a part of the cold air shielding wall of the drying treatment chamber, and a breathable mesh-like storage shelf for placing the food materials to be dried can be freely taken in and out, the loading and storage operation of the food materials to be dried can be made simpler and more efficient. By the heating means from the lower bottom surface in the drying treatment chamber, heat directly passes through the mesh and diffusion occurs, and the entire sealed space of the drying treatment chamber can be uniformly and efficiently heated.

[0038] In addition, the cold air shielding wall surrounding the drying treatment chamber other than the humidity adjustment window is made of a thick material such as ceramics or plastics having appropriate heat insulation properties. The humidity adjustment window provided on the cold air shielding wall of the upper top surface is a thin moisture permeable film or a moisture permeable film laminate with poor heat insulation properties. Therefore, the water vapor evaporated and diffused from the surface of the food materials to be dried is preferentially condensed on the partition surface of the humidity adjustment window of the moisture permeable film or the moisture permeable film laminate, and the water vapor moisture can be efficiently discharged from the humidity adjustment window to the outside of the drying treatment chamber.

[0039] As described above, the hydrophilic urethane-based resin film used for this moisture permeable film has the property that the moisture permeation amount increases significantly when dew condensation occurs and water is absorbed. Therefore, even when the temperature in the drying treatment chamber becomes higher than the temperature in the refrigerator compartment and the moisture evaporated from the food materials to be dried increases, the moisture permeation amount is automatically increased, and the dew condensation water does not drip into the drying treatment chamber, and continuous and stable drying humidity control becomes possible.

[0040] In addition, the temperature of the sealed space in the drying treatment chamber can detect the temperature by the temperature detection control means and control the heating means, and the temperature in the drying treatment chamber can be continuously and stably adjusted. Therefore, the temperature gradient and humidity gradient with the refrigerator compartment can be ensured, and a stable and smooth drying treatment can be promoted.

[0041] In addition, the refrigerator-freezer with a drying function according to the second aspect of the present invention is characterized in that the moisture permeable film laminate is formed by laminating the hydrophilic moisture permeable resin film serving as the moisture permeable film on a breathable base fabric, or by coating a hydrophilic moisture permeable resin.

[0042] According to this refrigerator-freezer with a drying function, when the base fabric and the moisture-permeable film are dry, the heat insulation property of the moisture-permeable film laminate is high. When the base fabric and the moisture-permeable film are wet, dew condensation water intervenes and the heat conduction increases, resulting in a deterioration of the heat insulation property. By taking advantage of the function of the base fabric's changing heat insulation property, when the base fabric is dry, the heat insulation property is high, preventing the heat in the drying chamber from being transferred to the refrigerator compartment and effectively maintaining the temperature in the drying chamber. When it is wet, the heat conduction is improved, promoting dew condensation on the moisture-permeable film on the inner side of the drying chamber and accelerating the evaporation to the outside of the drying chamber more quickly.

[0043] Furthermore, by making it a laminate, the resin film of the moisture-permeable film can be reinforced and the structural strength can be increased. It is also possible to integrally mold with a resin structure that serves as a shielding wall for the cold air circulation wind, facilitating the assembly and maintenance of the drying chamber and resulting in a structure that is easy to use and inexpensive. As its manufacturing method, either a laminate using an adhesive or a coating without using an adhesive may be used. However, although the moisture permeability is affected by the adhesive, laminating the resin film of the moisture-permeable film is recommended to form a stable film thickness.

[0044] Also, in the refrigerator-freezer with a drying function according to the third aspect of the present invention, the resin material of the moisture-permeable film is a hydrophilic urethane-based resin film with a glass transition temperature Tg set near the refrigeration temperature range of 0°C to 10°C. The base fabric is a breathable woven fabric or non-woven fabric such as nylon or polyester, and the moisture-permeable film laminate is formed by laminating the base fabric and the moisture-permeable film with an adhesive layer that is intermittently arranged at an appropriate interval.

[0045] According to this refrigerator-freezer with a drying function, since the glass transition temperature Tg is molecularly designed for the refrigeration compartment temperature range, when the temperature in the drying chamber is higher than that in the refrigerator compartment and the humidity decreases and dew condensation does not occur, the heat insulation property of the base fabric facing the refrigerator compartment side increases, the temperature of the moisture-permeable film rises, and the moisture permeability also increases. Thus, the drying process proceeds relatively smoothly while maintaining the temperature in the drying chamber.

[0046] In addition, when the temperature of the drying chamber or the moisture permeable membrane is in the range of 0°C to 10°C or lower and the dew point humidity is below this low temperature, a large moisture permeation amount will not occur, evaporation to the refrigerator side is suppressed, and the energy of the heating means on the lower bottom surface is only consumed for heating in the drying chamber, and the heating of the drying chamber proceeds efficiently. If the heating means is stopped, it can be applied and developed as a vegetable chamber where the humidity is maintained.

[0047] Also, by laminating with the adhesive layer dispersed at appropriate intervals, a resin film with a stable film thickness can be used as the moisture permeable membrane, and the influence of the adhesive on the moisture permeability can be eliminated by the width of the dispersed intervals.

[0048] Moreover, the refrigerator-freezer with a drying function according to the fourth aspect of the present invention is characterized in that the drying chamber is set such that the heat insulation performance of the moisture permeable membrane or the moisture permeable membrane laminate that forms the partition surface of the humidity control window is the lowest compared to the heat insulation performance of the cold air shielding wall that forms the sealed space.

[0049] According to this refrigerator-freezer with a drying function, among the wall surfaces constituting the drying chamber, the heat insulation performance of the partition surface of the humidity control window is the lowest, and it is set to be the most easily heat-passing compared to other cold air shielding wall portions. Therefore, the surface temperature of the inner side surface of the cold air shielding wall is the lowest at the portion of the moisture permeable membrane or the moisture permeable membrane laminate that forms the partition surface of the humidity control window. Thus, condensation concentrates on the moisture permeable membrane portion of the partition surface of the humidity control window, and by increasing the moisture permeation amount of the moisture permeable membrane, moisture inside can be efficiently transferred to the outside, condensation on other wall surfaces is almost eliminated, and safe and secure drying treatment can be performed without the occurrence of food spoilage due to excessive moisture.

[0050] As described above, for a refrigerator-freezer with a drying function that satisfies this function, if the food material to be dried is stored in the drying chamber and only the start button of the drying treatment operation is pressed, the drying chamber is heated to a predetermined temperature by an efficient heating means from the lower bottom surface. Due to the heating from the lower part, the moisture in the food material to be dried evaporates, and it moves using the temperature difference and water vapor partial pressure difference between the front and back of the moisture permeable membrane or the moisture permeable membrane laminate on the partition surface of the most cooled humidity control window, and the drying proceeds smoothly.

Effects of the Invention

[0051] As described above, by using a moisture permeable film, a sealed drying chamber can be formed. There is no odor transfer due to the leakage of the odor of the food material to be dried into other refrigerators or freezers. Also, instead of drying by the forced air of drying air, since the diffusion force of the water vapor partial pressure difference is efficiently utilized, it is a low-temperature drying process while wrapping the surface of the food material to be dried with moisture. Therefore, changes in color, nutrients, and tissue components can be suppressed, and a refrigerator or freezer with a drying function that can easily, quickly, and inexpensively produce high-quality dried food is provided.

Brief Description of the Drawings

[0052]

Figure 1

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Figure 13

Embodiments for Carrying Out the Invention

[0053] Hereinafter, a specific embodiment of the refrigerator-freezer with a drying function of the present invention will be described with reference to FIGS. 1 to 13. The technical scope of the present invention is not limited to these embodiments, and appropriate changes can be made as long as they do not contravene the spirit thereof.

[0054] FIG. 1 is a cross-sectional view mainly showing the drying treatment chamber 11 of the refrigerator-freezer 10 with a drying function according to the first embodiment of the present invention. FIG. 2 is a plan view seen from above of a humidity control window 16 provided with a moisture permeable film laminate 15 composed of a moisture permeable film 13 and a base fabric 14 attached to the upper ceiling shielding wall 12 of the drying treatment chamber 11 according to the first embodiment. FIG. 3 is a cross-sectional view taken along line (a)-(a) of the drying treatment chamber 11. FIG. 4 is an enlarged cross-sectional view taken along line (a)-(a) including the humidity control window 16 provided as a partition surface of the upper ceiling shielding wall 12 of the drying treatment chamber 11. FIG. 5 is a cross-sectional view showing a state in which the storage shelf 18 is taken out by releasing the opening / closing mechanism shielding wall 17 of the drying treatment chamber 11 that can be opened and closed. FIG. 6 is a cross-sectional view showing a state in which the storage shelf 18 is positioned in place in the drying treatment chamber 11 after the material to be dried 19 is set.

[0055] FIG. 7 is a graph showing the change in moisture permeability with temperature of hydrophilic urethane resin films having different glass transition points Tg of the moisture permeable film 13 of the moisture permeable film laminate 15. FIG. 8 is a comparison table showing the results of measuring the moisture permeability of hydrophilic urethane resin films having different glass transition points Tg as the moisture permeable film 13 of the moisture permeable film laminate 15 by the A-1 method and B-1 method of JIS-L1099.

[0056] Further, FIG. 9 is an illustrative diagram explaining the function of moisture movement on the surface of the moisture permeable film 13 of the humidity control window 16 provided as a partition surface of the upper ceiling shielding wall 12 of the drying treatment chamber 11. (1) shows the state of the moisture permeable film 13 immediately after storing the material to be dried 19 or when it is stably stored in refrigeration. (2) shows the state when water vapor condenses on the moisture permeable film 13. (3) is an illustrative cross-sectional view showing a state in which the degree of drying of the material to be dried 19 progresses and dew condensation on the moisture permeable film 13 disappears at a humidity below the water activity Aw value.

[0057] First, the configuration of the refrigerator-freezer 10 with a drying function according to the first embodiment will be sequentially described with reference to FIGS. 1 to 8.

[0058] The refrigerator-freezer 10 with a drying function is composed of a freezer compartment 20, a refrigerator compartment 21, and a drying treatment chamber 11. The freezer compartment 20, the refrigerator compartment 21, and the drying treatment chamber 11 are cooled by the cold air circulation wind 28 generated by a cooling fan 27 and a refrigeration system 26 in which a refrigerant composed of a compressor 22, a condenser 23, an expansion valve 24, and an evaporator 25 circulates.

[0059] That is, the refrigerant flowing in the refrigeration system 26 is first adiabatically compressed by the compressor 22 to pressurize the gaseous refrigerant, and the gaseous refrigerant that has become high temperature is cooled by the outside air in the condenser 23 and liquefied. Next, when the liquefied refrigerant passes through the expansion valve 24, the pressure drops and it vaporizes in the evaporator 25, thereby taking the heat of vaporization from the surroundings and cooling the evaporator 25. The vaporized refrigerant returns to the compressor 22 again, and the compressed and high-temperature refrigerant is sent to the condenser 23, and sequentially circulates in the refrigeration system 26.

[0060] In addition, in the outline description of the refrigeration system 26, the evaporator 25 is described as the member where the refrigerant circulating in the refrigeration system 26 evaporates. However, when it is cooled by heat exchange between the cold air circulation wind 28 formed by the cooling fan 27 flowing through the freezer compartment 20 and the refrigerator compartment 21 of the refrigerator-freezer 10 and the outer surface of the evaporator 25, the evaporator 25 is referred to as the cooler 25.

[0061] The outer surface temperature of the cooler (evaporator) 25 can set the evaporation temperature by the expansion valve 24. The evaporation temperature of a normal refrigerator-freezer is in the range of -25°C to -30°C. By the operation of the cooling fan 27, the cold air circulation wind 28 indicated by the arrow flowing in the refrigerator-freezer 10 flows through the evaporator space 29 where the cooler 23 is installed, and heat exchange occurs between the cold air circulation wind 28 and the surface of the cooler 25. Furthermore, the cold air circulation wind 28 circulates in the refrigerator-freezer 10 by airflow control with ductwork 41, a refrigerator-freezer damper thermostat 42, etc., and the refrigerator compartment 21 is cooled to about 5°C in the refrigerated temperature zone, and the freezer compartment 20 is cooled to about -25°C in the frozen temperature zone.

[0062] The cold air circulation wind 28 in the refrigerator compartment 21 flows around the drying chamber 11 having a sealed space 35 surrounded by a cold air shielding wall 30 installed in the refrigerator compartment 21. When the cold air contacts the cold air shielding wall 30, although it is indirect, the inside of the drying chamber 11 is also cooled by wall surface cooling.

[0063] In addition, the material forming the cold air shielding wall 30 of the drying chamber 11 is a hard plastics material or a ceramics material. In order to enhance the heat insulation property, the thickness of the cold air shielding wall 30 may be increased, or a foamed plastics material may be used.

[0064] The drying chamber 11 having a sealed space 35 surrounded by the cold air shielding wall 30 is a sealed box structure. However, there is an opening / closing mechanism shielding wall 17 at the front of the drying chamber 11 that can be opened and closed. The cold air shielding wall 30 of the upper ceiling shielding wall 12 of the drying chamber 11 has a humidity control window 16 provided as a partition surface formed by integrally molding a moisture permeable film laminate 15 of a moisture permeable film 13 and a base fabric 14.

[0065] Also, a heating means 32 such as an electric heater is installed on the lower bottom surface 31 of the sealed space 35 of the drying chamber 11. By cooperating with the temperature detection and control means 33 of the sealed space 35 of the drying chamber 11, the temperature of the sealed space 35 of the drying chamber 11 can be controlled.

[0066] Moreover, in the sealed space 35 of the drying chamber 11, there is a ventable mesh storage shelf 18 for storing the food material to be dried 19. By releasing the opening / closing mechanism shielding wall 17, it can be freely taken out. When storing it in the drying chamber 11, it is set to be located at the center of the upper surface of the electric heater of the heating means 32 on the lower bottom surface 31.

[0067] The moisture permeable film laminate 15 attached as a partition surface to the humidity control window 16 of the upper ceiling shielding wall 12 of the drying chamber 11 is composed of a moisture permeable film 13 made of a hydrophilic urethane-based resin film having a partially crystalline molecular structure in the non-porous film portion, and a base fabric 14 formed of a breathable fabric or non-woven fabric made of a breathable nylon or polyester fiber material, and is adhered via adhesive layers dotting at appropriate intervals.

[0068] When the temperature is below the glass transition temperature Tg, the gaps between the molecules of the resin contract, suppressing the water vapor permeation ability. When the temperature is above the glass transition temperature Tg, the molecular motion of the amorphous phase of the resin becomes active, expanding the gaps between the molecules of the resin, facilitating the diffusion of water vapor molecules, and improving the water vapor permeation ability.

[0069] To control this glass transition temperature Tg, it is necessary to synthesize polyurethane by varying various factors such as the ethylene oxide concentration of the polyurethane and the molecular weight of the polyol, and create an appropriate moisture permeability and glass transition temperature Tg according to the drying conditions. In the present invention, a polymer material with a glass transition temperature Tg in the vicinity of the refrigeration temperature range of 0°C to 10°C was selected.

[0070] Although it is one example, the curve (a) in Fig. 7 shows the result of measuring the moisture permeability at a predetermined temperature of the urethane resin film of the moisture permeable film 13 with a glass transition temperature Tg of 0°C to 10°C, indicating a state where the moisture permeability rapidly increases when the environmental temperature exceeds 10°C. The curve (b) is the moisture permeability curve of the urethane resin film with a glass transition temperature Tg of -30°C, showing a state where no significant change in moisture permeability is found even at temperatures exceeding 20°C.

[0071] Furthermore, since the urethane resin film of the moisture permeable film 13 is hydrophilic, the large dissolution of water vapor molecules has a synergistic effect, resulting in a moisture permeable film 13 with a rapid increase in moisture permeability in a dew condensation environment where the surface of the urethane resin film of the moisture permeable film 13 becomes wet.

[0072] The comparison table in Fig. 8 shows the results of measuring the moisture permeability of the moisture permeable film 13 of various urethane resin films by the moisture permeability measurement method of JIS-L1099, comparing and showing the results measured by the A-1 method and the B-1 method.

[0073] The big difference between the measurement methods of Method A-1 and Method B-1 is that Method A-1 measures the moisture permeability through the moisture permeable membrane 13 with 90% air and a calcium chloride moisture absorbent at 40°C, while Method B-1 measures through the moisture permeable membrane 13 with a potassium acetate solution as the moisture absorbent and water at 23°C. There is a difference in whether the comparison surface of the moisture permeable membrane 13 is immersed in water or in the air.

[0074] From the results of the comparison table in Figure 8, regardless of the difference in the glass transition temperature Tg, the moisture permeable membrane 13 of the hydrophilic urethane resin film shows a difference of 2 to 6 times between the results in the air and the results in the state of being immersed in water, indicating that the moisture permeation amount increases when the moisture permeable membrane 13 gets wet. Considering that the temperatures during the measurement of Method A-1 and Method B-1 are 40°C and 23°C respectively, the moisture permeation amount of Method B-1 with a lower temperature is larger, so it can be said that the influence of temperature is not significant.

[0075] It should be noted that Method B-1 uses a potassium acetate solution and water at 23°C, and it is also considered that the moisture permeability due to the osmotic pressure caused by the potassium acetate concentration difference is taken into account. However, even in the results of separately measuring the moisture permeation amount under the condition of condensing water on the moisture permeable membrane 13 covering the cup by changing the temperature of the water in the cup from 10°C to 30°C in an environment of 10°C, the moisture permeation amount obtained at 20°C is 4 to 5 times that at 10°C, and at 30°C it is about 10 times that at 10°C. It has been confirmed that the improvement of the moisture permeation amount under the condensation condition is an undeniable fact.

[0076] In addition, the main body of the refrigerator-freezer 10 with a drying function is composed of a heat-insulating box body 38, a freezer door 39, and a refrigerator door 40 to form a freezer 20 and a refrigerator 21. The control device 37 for controlling the temperature in the drying treatment chamber 12 is attached to the front of the refrigerator door 40.

[0077] Also, the cold air circulation wind 28 to the refrigerator 21 sends the cold air in the evaporator space 29 through the duct work 41 at the back of the refrigerator 21 by the cooling fan 27 and returns it into the evaporator space 29 from the air inlet 43 after circulating through the refrigerator 21 from the outlet of the damper thermostat 42.

[0078] Next, with reference to Fig. 9 as well, the operation of the refrigerator-freezer 10 with a drying function having this configuration will be described.

[0079] When the power cord (not shown) of the refrigerator-freezer 10 with a drying function is connected to a commercial power supply, the compressor 22 operates, and the refrigerant in the refrigeration system 26 is compressed in the compressor 22 to become high-temperature and high-pressure and then moves to the condenser 23. The high-temperature and high-pressure refrigerant carried to the condenser 23 is cooled by the low-temperature outside air and its temperature drops and it liquefies. Next, when passing through the expansion valve 24, the refrigerant vaporizes by suddenly dropping in pressure in the evaporator 25, taking away the latent heat of evaporation and cooling the evaporator 25. The refrigerant with the reduced pressure returns to the compressor 22 again, is compressed to become high-temperature and high-pressure, and circulates in the refrigeration system 26.

[0080] Next, by flowing the cold air circulation wind 28 by the operation of the cooling fan 27 in the evaporation space 29 where the cooled evaporator 25, that is, the cooler 25, is housed, the outer surface of the cooler 25 and the cold air circulation wind 28 exchange heat and are cooled. The cold air circulation wind 28 is created by the cooling fan 27, and by the action of the ductwork 41 and the damper thermostat 42 configured on the back surfaces of the freezer compartment 20 and the refrigerator compartment 21, etc., it becomes the flow indicated by the arrow so as to uniformly cool the freezer compartment 20 and the refrigerator compartment 21 at an appropriate temperature.

[0081] In particular, the cold air circulation wind 28 that cools the refrigerator compartment 21 indirectly cools the inside of the drying treatment chamber 11 by coming into contact with the surrounding cold air shielding wall 30 surface including the upper ceiling shielding wall 12 and the opening / closing mechanism shielding wall 17 of the drying treatment chamber 11 located inside the refrigerator compartment 21 as it flows through the refrigerator compartment 21. Also, the cold air circulation wind 28 comes into contact with the surface of the moisture permeable film laminate 15 integrally formed as the partition surface of the humidity control window 16 provided on the upper ceiling shielding wall 12.

[0082] The cold air circulation wind 28 that has flowed through the inside of the refrigerator compartment 21 and around the drying treatment chamber 11 flows through the evaporation space 29 again from the intake port 43, exchanges heat on the surface of the cooler 25, and circulates through the ductwork 41 and the damper thermostat 42 by the cooling fan 27 and returns to the inside of the refrigerator compartment 21 again.

[0083] On the surface of the cooler 25, not only heat exchange occurs, but also the moisture absorbed when flowing through the refrigerator compartment 21 is removed. That is, since the surface temperature of the cooler 25 is set to the evaporation temperature of the refrigerant at -25°C to -30°C, it is approximately -25°C. Calculated from the absolute humidity (4.91E-04 (kg-water vapor / kg-dry air)) with -25°C as the dew point, the relative humidity is 10% or less at 5°C. Therefore, the excess moisture of 10% or more will condense and dew on the surface of the cooler 25. Thus, when the cooling by this cold air circulation wind 28 is continuously performed, the relative humidity in the refrigerator compartment 21 will theoretically be 10% or less.

[0084] Next, the inside of the drying treatment chamber 11 can be heated by heating means 32 such as an electric heater installed on the lower bottom surface 31 of the sealed space 35. Usually, the upper limit of the surface temperature of the electric heater is set to 40°C, and a temperature fuse 34 is attached for safety. The temperature of the sealed space 35 in the drying treatment chamber 11 is temperature-controlled by turning the electric heater, which is the heating means 32, on and off by the temperature detection control means 33 around the set temperature.

[0085] If the relative humidity in the drying treatment chamber 11 is estimated when the temperature in the drying treatment chamber 11 is set to 30°C, since the moisture permeable membrane 13 functions properly and the refrigerator compartment 21 is in an environmental condition of 5°C with a relative humidity of 10%, the sealed space 35 in the drying treatment chamber 11 can be dehumidified to the same equilibrium absolute humidity. That is, when the drying treatment chamber is at 30°C, it is calculated that the relative humidity reaches equilibrium at 2% or less, and it can be said that the drying treatment of the foodstuff to be dried 19 proceeds smoothly.

[0086] Next, the method of storing the foodstuff to be dried 19, the drying treatment operation method, and its action mechanism in the refrigerator-freezer 10 with a drying function will be described.

[0087] First, operate the refrigerator-freezer 10 with a drying function continuously, confirm that the inside of the refrigerating chamber 21 is stably cooled, and open the front refrigerating chamber heat-insulating door 36. Next, pull the handle of the opening / closing mechanism shielding wall 17 in front of the drying chamber 11 forward to open the sealed space 35, pull out the storage shelf 18 that can be freely taken in and out, and spread the prepared food materials 19 to be dried on the plurality of storage shelves 18 of the storage shelf 18 at appropriate intervals. The food materials 19 to be dried should be sliced as thinly as possible to complete the drying process in a short time, but it is necessary to make the thickness such that the chewing texture of the food materials is not impaired.

[0088] Return the storage shelf 18 on which the food materials 19 to be dried are placed to a fixed position at the center, such as an electric heater, which is the heating means 32 on the lower bottom surface 31 of the sealed space 35 of the drying chamber 11, close the opening / closing mechanism shielding wall 17, and make the sealed space 35 of the drying chamber 11 in a sealed state.

[0089] After that, close the refrigerating chamber door 36 of the refrigerating chamber 21 of the refrigerator-freezer 10, press the drying process switch (not shown) of the control device 37 attached to the front of the refrigerating chamber door 36, and start the drying process.

[0090] When starting the drying process, first, heating by the heating means 32 such as an electric heater starts. There is a heating means 32 for the electric heater, such as a PTC heater, whose resistance value increases and controls the current when it reaches a certain temperature. Usually, it is safe to cut off the heating means 32 with a temperature fuse 34 when it reaches about 40°C or higher.

[0091] When the drying process is set at 30°C by the control device 37, the temperature detection and control means 33 at the upper part of the sealed space 35 of the drying chamber 11 detects 30°C, and the temperature of the sealed space 35 of the drying chamber 11 can be controlled at 30°C by turning the heating means 32 on and off.

[0092] When the storage shelf 18 is stored in the drying chamber 11, the environment inside the drying chamber 11 takes in the standard environment of about 25°C and about 60% in terms of the temperature and humidity of the outside air, and it will temporarily condense on the inner wall surface of the cooled drying chamber 11. However, when it stabilizes, the inner wall surface of the drying chamber 11 and the food material to be dried 19 also start to cool down and settle at about 5°C.

[0093] Regarding the humidity in the sealed space 35 of the drying chamber 11, even when the temperature is 5°C, the moisture adhering to the food material to be dried 19 or, if the fresh produce is the food material to be dried 19, due to its respiration, etc., the free water, etc. in the food material to be dried 19 evaporates, so the humidity rises to the humidity of the water activity Aw value specific to the food material to be dried 19. When the water vapor pressure in the drying chamber 11 rises and becomes higher than the water vapor pressure in the refrigerator compartment 21, the moisture in the drying chamber 11 permeates through the moisture permeable film 13 attached to the humidity adjusting window 16 provided as the partition surface of the upper ceiling shielding wall 12, so the humidity in the sealed space 35 in the drying chamber 11 decreases.

[0094] This moisture permeable film 13 material is a urethane resin material having a glass transition point Tg in the hydrophilic refrigeration temperature range of 0°C to 10°C. While the temperature in the sealed space 35 of the drying chamber 11 is low, since the partition surface of the humidity adjusting window 16 is also at the same temperature, the moisture permeable film 13 is also below the glass transition point Tg and the moisture permeability is low and drying is suppressed. As it is, the relative humidity, which is the water activity Aw value of the food material to be dried 19, stabilizes at about 90%.

[0095] When fresh vegetables are stored as the vegetable compartment, the temperature and humidity rise due to the respiration of the fresh vegetables, and the moisture permeable film 13 exhibits its moisture permeation function to adjust the humidity, thus creating a high-humidity environment without condensation at an appropriate temperature, and becoming a room where fresh vegetables can be stored for a long time.

[0096] Therefore, in order to function as the drying treatment chamber 11, it is necessary to start the drying treatment by pressing a switch in the control device 37. As the temperature in the drying treatment chamber 11 rises, the food material 19 to be dried is also heated, and the moisture adhering to the food material 19 and the free water in the food material will evaporate. When the drying treatment chamber 11 is at a low temperature, the moisture permeable membrane 13 is in a glassy state and the amount of water vapor passing through is low. For a while, as the temperature in the drying treatment chamber 11 rises, the humidity will also rise.

[0097] However, the cold air shielding wall 30 of the drying treatment chamber 11 is made of ceramics or plastic material with relatively poor thermal conductivity and a thickness of about 3 mm, and has heat insulation properties. The inner surface is not easily affected by the refrigerating chamber 21 and is warmed as the temperature of the drying treatment chamber 11 rises. In that regard, the boundary surface between the inner side and the outer side of the partition surface of the humidity adjusting window 16 is a moisture permeable membrane laminate 15 obtained by laminating the moisture permeable membrane 13 on the base fabric 14, with a thickness of 1 mm or less. It has worse heat insulation properties than other inner wall surfaces, is affected by the refrigerating chamber 21, and preferentially the temperature of the inner surface of the drying treatment chamber 11 drops and condensation begins.

[0098] The moisture permeable membrane 13 of the present invention uses a hydrophilic urethane-based polymer membrane (resin film). When this moisture permeable membrane 13 gets wet due to condensation, as shown in the comparison table of FIG. 8, it has the property that the moisture permeation amount increases several times. That is, when the inside of the drying treatment chamber 11 was in the initial state and was cooled in the refrigeration temperature range with no condensation and a small moisture permeability, when condensation began on the moisture permeable membrane 13 on the partition surface of the humidity adjusting window 16, the moisture permeation amount increased at the same time, and the condensed moisture moved to the refrigerating chamber 21 side and evaporated.

[0099] Therefore, moisture condenses on the moisture permeable membrane 13 that forms the partition surface of the humidity adjusting window 16. However, as a characteristic of the moisture permeable membrane 13 itself, the moisture permeation amount jumps up about 5 times, so moisture permeation proceeds smoothly, and water droplets do not drip into the storage, and the permeation of moisture progresses.

[0100] While the inside of the drying chamber 11 is still being warmed by the heating means 32 on the lower bottom surface 31 and its temperature is rising, and dew condensation is occurring on the moisture permeable membrane 13, the moisture permeable membrane 13 absorbs the condensation heat on the side surface of the sealed space 35 of the drying chamber 11 and takes away the evaporation heat on the surface of the base fabric 14 side of the moisture permeable membrane 13 facing the refrigerating chamber 21, so that it is relatively stably maintained at around 5°C. Therefore, the moisture from the heated food material 19 to be dried evaporates and dehydrates, and the drying process continues.

[0101] However, as the drying of the food material 19 to be dried progresses and the amount of moisture evaporated from the food material 19 to be dried decreases, the water vapor partial pressure value in the drying chamber 11 becomes smaller, the dew condensation on the moisture permeable membrane 13 decreases, and eventually disappears. When it disappears, the temperature of the moisture permeable membrane 13 will rise under the influence of the temperature in the drying chamber 11.

[0102] This moisture permeable membrane 13 material is a hydrophilic material having a glass transition point Tg in the refrigerating temperature range of 0°C to 10°C, and the moisture permeation amount is suppressed while the temperature is low. However, when the temperature of the moisture permeable membrane 13 rises above 20°C, in the rubber-like temperature region above the glass transition point Tg, the molecular structure loosens and the moisture permeation increases significantly. As shown by the curve in Fig. 7(a), the moisture permeation amount increases by more than three times at 10°C and 30°C. Even when the temperature of the moisture permeable membrane 13 is above the refrigerating chamber temperature, the moisture permeation amount is ensured and smooth drying proceeds.

[0103] Next, when the refrigerating chamber 21 is stably cooled in the refrigerating temperature range, the function of the moisture permeable membrane 13 in the process of the temperature of the sealed space 35 of the drying chamber 11 rising by the heating means 32 will be described in detail with reference to Figs. 9(1), (2), and (3).

[0104] First, the state in Fig. 9(1) shows that the food material 19 to be dried is placed and stored on the storage shelf 18, and then the temperature in the drying chamber 11 is also stable at 5°C. That is, the cold air circulation wind 28 flowing through the refrigerating chamber 21 is heat-exchanged by the cooler 25 with a surface temperature of -25°C, and at the same time, moisture is also removed, and the temperature is adjusted by the blowing amount of the damper thermo 42.

[0105] Therefore, the cold air circulation wind 28 condition is calculated to have a temperature of 5°C and a relative humidity of 9.2%. At this time, the environment of the sealed space 35 in the drying chamber 11 is 5°C, and it is estimated that the humidity is about 90% due to the influence of the evaporated moisture from the food material 19 to be dried. That is, the water vapor partial pressure at 5°C and 9.2% is 0.8 hPa, and the water vapor partial pressure at 5°C and 90% is 7.9 hPa. Therefore, the water vapor partial pressure difference is about 7.1 hPa, and this water vapor partial pressure difference becomes the driving force for drying to proceed. However, this moisture permeable membrane 13 material is a material having a glass transition point Tg in the hydrophilic refrigeration temperature range, and the moisture permeation amount is suppressed on the surface of the moisture permeable membrane 13 while the temperature is low.

[0106] Note that the relationship between temperature, humidity, and water vapor partial pressure is based on the values calculated according to Tetens' formula.

[0107] Next, the state of Fig. 9(2) shows the process in which the heating of the sealed space 35 in the drying chamber 11 progresses and rises from 5°C to 30°C. At this stage, if the temperature on the surface of the moisture permeable membrane 13 is maintained at 5°C, the absolute humidity at which condensation occurs is 5.4E-03 (kg-water vapor / kg-dry air), and when converted to the relative humidity at 30°C, it is 21%. That is, while the relative humidity in the drying chamber 11 is kept at 21% or more, condensed water is formed on the surface of the moisture permeable membrane 13, and a large moisture permeation amount is maintained.

[0108] Normally, considering that the condensation rate is fast and the diffusion rate of humidity from the surface of the food material 19 to the surface of the moisture permeable membrane 13 is also relatively fast, the drying rate at which moisture jumps out from the surface of the food material 19 becomes the rate-determining step. The water vapor partial pressure difference greatly affects this rate. The environment on the surface of the food material 19 to be dried has a temperature of 30°C, a relative humidity of 100%, and a water vapor partial pressure of 42.4 hPa. The environment on the surface of the moisture permeable membrane 13 has a temperature of 5°C and a relative humidity of 100%, which is 8.7 hPa. The water vapor partial pressure difference has a large driving force of 33.7 hPa. Therefore, it can be said that there is a drying rate equivalent to natural drying under the environment of 21% at 30°C.

[0109] Here, what should be additionally considered is that the permeation amount during condensation can be presumably said to be the penetration power into the moisture permeable film. The hydrophilic urethane resin film has a high compatibility with water and penetrates relatively quickly. In the comparison table of Fig. 8, the moisture permeability of the hydrophilic urethane resin film is described by comparing the results measured by the A-1 method and the B-1 method of JIS-L1099. It can be said that the reason for the larger result measured by the B-1 method is the influence of the penetration power.

[0110] Next, the moisture that has penetrated through the moisture permeable film 13 transfers to the breathable fabric or non-woven fabric base cloth 14 formed as the moisture permeable film complex 15, which is composed of a moisture permeable film and a breathable nylon or polyester fiber material adhered via adhesive layers scattered at appropriate intervals. The adhesive layers are scattered at intervals and have little influence on the moisture permeability, air permeability, and penetrability, and can be ignored here.

[0111] The state in which condensed water is interposed in the moisture permeable film complex 15 composed of the moisture permeable film 13 and the base cloth 14 means that the moisture permeable film 13 has a large drying area as a whole. The vapor pressure difference of 7.9 hPa between the environmental conditions on the surface of the moisture permeable film complex 15, temperature 5°C, relative humidity 100%, 8.7 hPa, and the conditions of the cold air circulation wind 28, temperature 5°C, relative humidity 9.2%, water vapor pressure 0.8 hPa becomes the drying driving force.

[0112] Next, the state of Fig. 9(3) shows that the heating in the drying treatment chamber 11 progresses, the temperature rises to 30°C, and furthermore, the amount of moisture evaporation from the food material to be dried 19 extremely decreases, and the relative humidity in the drying treatment chamber 11 becomes 21% or less, and there is no condensation on the moisture permeable film 13.

[0113] In this state, both the moisture permeable film 13 and the base cloth 14 are dry, and an improvement in the moisture permeability due to the water penetration power cannot be expected. However, since the temperature of the moisture permeable film 13 is 30°C, which is a temperature above the glass transition point Tg, if the material of Fig. 7(i) is used as the moisture permeable film 13, the moisture permeability will be maintained at a high level, and the drying process will proceed in an ideal environment where the food material to be dried 19 is under the drying condition of 2% at 30°C.

[0114] Note that the factor that stabilizes the temperature of the moisture permeable membrane 13 is the change in the heat insulation property of the base fabric 14 attached to the moisture permeable membrane 13 that becomes the moisture permeable membrane laminate 15. The base fabric 14 is a woven or non-woven fabric of nylon fiber or polyester fiber, and the air layer contained in the fiber has a certain degree of heat insulation property. However, when water intervenes due to dew condensation, it shows a phenomenon in which the heat conduction improves due to capillary action sucking in water, resulting in a decrease in heat insulation property.

[0115] That is, by making the urethane resin film of the moisture permeable membrane 13 face the inner surface side of the sealed space 35 of the drying treatment chamber 11 and bonding the base fabric 14 to the refrigerator compartment 21 side, when dew condensation occurs, the heat insulation property deteriorates due to the dew condensation water, and the dew condensation further progresses and evaporation also progresses. However, when it becomes dry, the heat insulation property of the base fabric 14 increases, and the moisture permeable membrane 13, affected by the temperature of the sealed space 35, works to maintain the moisture permeation amount and suppress the heat exchange between the drying treatment chamber 11 and the refrigerator compartment 13, resulting in energy-saving drying treatment.

[0116] Furthermore, the drying method using the moisture permeable membrane 13 of the present invention is not drying by forcibly blowing dried air onto the food material 19 to be dried, but drying by the water vapor partial pressure difference. Therefore, the cells of the food material 19 to be dried are dried while being wrapped in a water molecule membrane. In particular, the drying condition with a water vapor partial pressure difference of about 8 hPa is maintained from the initial stage of drying to the end point of drying. This driving force is effective for drying, and the force for drying increases due to the overlap of the upward air flow of air due to the temperature difference.

[0117] By utilizing this water vapor partial pressure difference force in the refrigerator, the present invention results in a drying treatment function with high superiority, where the surface of the food material 19 to be dried has little color change and oxidation deterioration is also suppressed. Furthermore, since it is not frozen, there is little destruction of cell tissue and nutrients.

[0118] Next, the drying treatment ends with the electric heater, which is the heating means 32, being stopped by timer control. The sealed space 35 of the drying treatment chamber 11 is gradually cooled by the cold air circulation wind 28 circulating through the refrigerator compartment 21 and becomes the refrigerated temperature zone. Therefore, the food material 19 to be dried may be left as it is, but it is recommended to take out the food material 19 to be dried at the end of drying, put it in a sealed container, and store it in the refrigerator or freeze it.

[0119] After the drying process is completed and the moisture-free dried food materials are frozen, there is little cell destruction and an appropriate texture remains. By devising the degree of dryness and the freezing temperature range, it is considered possible to preserve raw vegetables with residual pectin and a crispy texture for a long time using this drying method.

[0120] Also, at the start of the drying process, due to the condensation on the moisture-permeable membrane 13, a significant increase in the moisture permeability will cause the moisture adhering to the fresh food materials and free water to quickly evaporate, and it is possible to quickly reach the water activity Aw value of each food material to be dried 19. This also has the effect of maintaining the initial quality and suppressing the growth of miscellaneous bacteria.

[0121] Also, according to the refrigerator-freezer 10 with a drying function of the first embodiment of the present invention, when it is not used as the drying treatment chamber 11, the inside of the drying treatment chamber 11 is indirectly cooled naturally through the opening and closing mechanism shielding wall 17, the cold air shielding wall 30, etc., and the temperature and humidity range suitable for the vegetable chamber is maintained. However, in the structure as the drying treatment chamber 11, since the cooling as a refrigerator becomes dull, it may be provided with a ventilation port for directly taking in cold air manually or automatically into the drying treatment chamber 13 and made a part of the refrigerator compartment 21.

[0122] Next, the drying treatment chamber 51 mounted on the refrigerator-freezer 50 with a drying function of the second embodiment of the present invention will be sequentially described with reference to FIGS. 10 to 13. Note that the description of the same components as those of the refrigerator-freezer 10 with a drying function of the first embodiment will be omitted or simplified.

[0123] FIG. 10 is a cross-sectional view showing a state in which the drying treatment chamber 51 is installed in the refrigerator-freezer 50 with a drying function according to the second embodiment of the present invention. FIG. 11 is a plan view (1) and a cross-sectional view (2) of the drying treatment chamber 51 according to the second embodiment. FIG. 12 is a cross-sectional view showing a state in which the food materials to be dried 67 are stored in the sealed space 66 of the drying treatment chamber 51 and assembled as the drying treatment chamber 51. FIG. 13 is a cross-sectional view of the refrigerator-freezer 50 when the drying treatment chamber 51 according to the second embodiment is removed.

[0124] The refrigerator-freezer 50 with a drying function according to the second embodiment is composed of a freezer compartment 52, a refrigerator compartment 53, and a drying treatment chamber 51. The refrigeration system 54 in which the refrigerant circulates is the same as that of the first embodiment. The cold air circulation wind 57 caused by the cooling fan 56 cools the freezer compartment 52, the refrigerator compartment 53, and the drying treatment chamber 51.

[0125] Also, similarly, for the cooler (evaporator) 55, the outer surface temperature is in the range of -25°C to -30°C. By the operation of the cooling fan 56, the cold air circulation wind 57 indicated by the arrow flowing inside the refrigerator-freezer 50 is formed. By flowing through the evaporator space 58 where the cooler 55 is installed, heat exchange occurs between the cold air circulation wind 57 and the surface of the cooler 55. Furthermore, the cold air circulation wind 57 circulates inside the refrigerator-freezer 50 by airflow control with the ductwork 59, the refrigeration and freezing damper thermostat 60, etc. The refrigerator compartment 53 is cooled to approximately 5°C in the refrigeration temperature zone, and the freezer compartment 52 is cooled to approximately -25°C in the freezing temperature zone.

[0126] The cold air circulation wind 57 inside the refrigerator compartment 53 flows through the cold air shielding wall 87 of the drying treatment chamber 51 installed inside the refrigerator compartment 53. When the cold air circulation wind 57 contacts the cold air shielding wall 87 of the drying treatment chamber 51, although it is indirect, the sealed space 66 of the drying treatment chamber 51 is also cooled by wall surface cooling.

[0127] Note that the drying treatment chamber 51 is composed of a bottom container shielding wall 61 and an opening / closing mechanism shielding wall 62. By bonding the flange lower part 63 of the bottom container shielding wall 61 and the flange upper part 64 of the opening / closing mechanism shielding wall 62 with a latch mechanism 65, a sealed space 66 is formed. In the sealed space 66, a two-stage breathable mesh storage shelf with a lower storage shelf 68 and an upper storage shelf 69 on which the food ingredients to be dried 67 can be placed is set.

[0128] On the lower surface of the bottom container shielding wall 61, a bottom lining plate 70 such as an aluminum plate with good thermal conductivity is integrally formed with the bottom container shielding wall 61. On the upper ceiling shielding wall 88 part of the opening / closing mechanism shielding wall 62, there are a plurality of humidity control windows 71. A moisture permeable film laminate 72 is attached to the partition surface of the humidity control window 71, which serves as the boundary surface between the inside and outside of the drying treatment chamber 51.

[0129] The moisture-permeable film laminate 72 is formed by adhering a moisture-permeable film 73 made of a hydrophilic urethane-based resin film to a base fabric 74 formed of a woven fabric or a non-woven fabric made of a breathable nylon or polyester fiber material, with adhesive layers interspersed at appropriate intervals. On the partition surface of the humidity control window 71, the base fabric 74 is placed on the outside of the refrigerator compartment side, and the moisture-permeable film 73 is placed on the inside of the hermetic space 66 side of the drying treatment chamber 51, and the moisture-permeable film laminate 72 is attached.

[0130] The materials of the bottom container shielding wall 61 and the opening / closing mechanism shielding wall 62 that form the hermetic space 66 of the drying treatment chamber 51 are made of hard plastics materials or ceramic materials, and the thickness is increased to enhance the heat insulation performance, and a foamed plastic material may also be used. The moisture-permeable film laminate 72 that partitions the humidity control window 71 has a thickness of 1 mm or less with the moisture-permeable film 73 laminated on the base fabric 74, has worse heat insulation performance than other wall surfaces, is affected by the temperature of the refrigerator compartment 53, and the hermetic space 66 side of the moisture-permeable film laminate 72 is more likely to be cooled preferentially.

[0131] There is a planar recess 75 on the outer surface of the aluminum bottom plate 70 on the lower surface of the bottom container shielding wall 61 of the drying treatment chamber 51, and it is fitted by mating with the convex surface 86 of the heating means 76 attached to the heat insulation partition 85 located on the bottom surface of the refrigerator compartment 53 of the refrigerator-freezer 50, so that the central part of the bottom plate 70 of the drying treatment chamber 51 is set at the central part of the heating means 76.

[0132] As the heating means 76, a convex surface 86 is formed by incorporating a PTC heater 78 that is constant at about 40 °C together with a temperature detection and control means 79 at the center on the surface of a ceramic plate 77 rich in heat resistance and heat insulation. By closely adhering by mating the planar recess 75 on the outer surface of the aluminum bottom plate 70 and the convex surface 86 of the PTC heater 78, the temperature of the hermetic space 66 is detected by the temperature detection and control means 79, and the temperature of the hermetic space 66 can be controlled by turning the heating means 76 on and off.

[0133] In addition, the main body of the refrigerator-freezer 50 with a drying function is composed of a heat insulation box 80, a freezer door 81, and a refrigerator door 82 to form a freezer compartment 52 and a refrigerator compartment 53, and a control device 83 for controlling the temperature of the hermetic space 66 is attached to the front of the refrigerator door 82.

[0134] In addition, the cold air circulation wind 57 to the refrigerator compartment 53 sends the cold air in the evaporator space 58 through the duct work 59 on the back of the refrigerator compartment 53 by the cooling fan 56 and is sent out from the damper thermostat 60 outlet, circulates through the refrigerator compartment 53, and returns into the evaporator space 58 from the air inlet 84.

[0135] The moisture permeable film laminate 72 attached to the humidity control window 71 of the upper ceiling shielding wall 88 of the opening and closing mechanism shielding wall 62 of the drying treatment chamber 51 is exactly the same as the moisture permeable film laminate 15 in the first embodiment, and the description of its form, configuration, performance and characteristics as the moisture permeable film is omitted here.

[0136] Next, the method of storing the food material 67 to be dried, the drying treatment operation method and its action mechanism in the refrigerator-freezer 50 with a drying function will be described.

[0137] First, confirm that the refrigerator-freezer 50 with a drying function is continuously operated and the inside of the refrigerator compartment 53 is stably cooled, and open the front refrigerator compartment heat insulation door 81. Next, take out the drying treatment container that becomes the drying treatment chamber 51, remove the latch mechanism 65, and divide the opening and closing mechanism shielding wall 62 and the bottom container shielding wall 61.

[0138] Next, place the prepared food material 67 to be dried on the upper storage shelf 68 and the lower storage shelf 69 at appropriate intervals. In order to complete the drying treatment in a short time, the food material 67 to be dried is preferably sliced as thinly as possible, but it is preferably set to a thickness that does not impair the chewiness of the food material.

[0139] After placing the dried food ingredients 67 on the upper storage shelf 68 and the lower storage shelf 69, the storage shelf is put back into the bottom container shielding wall 61, closed with the opening and closing mechanism shielding wall 62 from above, and the latch mechanism 65 is closed to form a sealed space 66, which serves as a drying treatment container for the drying treatment chamber 51. The flat recess 75 at the bottom of the drying treatment container that becomes the drying treatment chamber 51 is fitted by mating with the convex surface 86 formed by the heating means 76 of the PTC heater 78 and the temperature detection and control means 79, so that the center of the drying treatment chamber 51 is set to the center of the heating means 76. By this operation, the aluminum bottom lining plate 70 at the bottom of the bottom container shielding wall 61 and the heating means 76 will be in close contact.

[0140] After that, close the refrigerator door 82 of the refrigerating chamber 53 of the refrigerator-freezer 50, and press the drying treatment switch (not shown) of the control device 83 attached to the front of the refrigerator door 82 to start the drying treatment.

[0141] When starting the drying treatment, first, the heating by the heating means 76 of the PTC heater 78 located in the flat recess 75 on the back surface of the bottom container shielding wall 61 of the drying treatment container in the drying treatment chamber 51 starts. When the heating by the heating means 76 starts, the convex surface 86 of the PTC heater 78 is in close contact with the flat recess 75, and the bottom lining plate 70 forming the flat recess 75 is an aluminum plate with good thermal conductivity. The sealed space 66 will be heated by the heating of the bottom lining plate 70.

[0142] This PTC heater 78 increases its resistance value and controls the current when it reaches 40°C. However, when performing the drying treatment of the sealed space 66 in the drying treatment chamber 51 at 30°C, the temperature detection and control means 79 at the center of the PTC heater 78 detects 30°C, turns the heating means 76 on and off, and can control the temperature of the sealed space 66 in the drying treatment chamber 51 to 30°C.

[0143] When the drying treatment container in the drying treatment chamber 51 is closed by the opening / closing mechanism shielding wall 62, the environment in the sealed space 66 takes in a standard environment of about 25°C and about 60% which is the temperature and humidity of general outside air. In the sealed space 66 of the cooled drying treatment chamber 51, condensation may occur on the inner wall surface, but when it stabilizes, both the inner wall surface of the sealed space 66 in the drying treatment chamber 51 and the food material to be dried 67 are cooled and settle at about 5°C.

[0144] Regarding the humidity in the sealed space 66 of the drying treatment chamber 51, even when the temperature is 5°C, the moisture adhering to the food material to be dried 67 and the free water in the food material to be dried 67 evaporate, so the humidity rises to the humidity of the water activity Aw value peculiar to the food material to be dried 67.

[0145] When the water vapor partial pressure in the sealed space 66 of the drying treatment chamber 51 rises and becomes higher than the water vapor partial pressure in the refrigerator compartment 53, due to the function of the moisture permeable membrane 73 of the humidity adjusting window 71 provided on the upper ceiling shielding wall 88 of the opening / closing mechanism shielding wall 62, the water vapor moisture in the sealed space 66 of the drying treatment chamber 51 permeates into the refrigerator compartment 52 and the humidity in the sealed space 66 of the drying treatment chamber 51 decreases.

[0146] The material of this moisture permeable membrane 73 is a urethane resin having a glass transition point Tg in the hydrophilic refrigeration temperature range of 0°C to 10°C. When the temperature in the sealed space 66 of the drying treatment chamber 51 is as low as 5°C, the temperature on the surface of the humidity adjusting window 71 is also the same. Therefore, the moisture permeable membrane 73 is also below the glass transition point Tg and the moisture permeability is low, and drying is suppressed. As it is, it stabilizes at a relative humidity of about 90% which is the water activity Aw value of the food material to be dried 67.

[0147] When storing fresh vegetables as a vegetable compartment, the temperature and humidity rise due to the respiration of the fresh vegetables, and the moisture permeable membrane 73 exhibits a moisture permeation function to adjust the humidity. Therefore, it creates an environment with an appropriate temperature and high humidity without condensation for the vegetables, and becomes a room where fresh vegetables can be stored for a long time.

[0148] Therefore, when the drying process starts, as the temperature of the sealed space 66 in the drying chamber 51 rises, the food material to be dried 67 is also heated, and the moisture adhering to the food material to be dried 67 and the free water in the food material evaporate. When the sealed space 66 in the drying chamber 51 is at a low temperature, the moisture permeable membrane 73 is in a glass state and the amount of water vapor passing through is low. For a while, as the temperature of the sealed space 66 in the drying chamber 51 rises, the humidity also rises.

[0149] However, the cold air shielding walls 87 of the bottom container shielding wall 61 and the opening / closing mechanism shielding wall 62 that form the sealed space 66 serving as the drying chamber 51 are made of ceramics or plastic materials with relatively poor thermal conductivity and a thickness of about 3 mm, and have heat insulation properties. The inner surface is hardly affected by the temperature of the refrigerator compartment 53, and the inner wall surface is warmed as the temperature of the sealed space 66 serving as the drying chamber 51 rises.

[0150] In that regard, the moisture permeable membrane laminate 72 provided at the boundary between the inside and outside of the humidity control window 71 surface of the upper ceiling shielding wall 88 of the opening / closing mechanism shielding wall 62 has a thickness of 1 mm or less, and has worse heat insulation properties than the surfaces of the other cold air shielding walls 87. It is affected by the temperature of the refrigerator compartment 53 and is very cold, so dew condensation starts preferentially.

[0151] The moisture permeable membrane 73 of the present invention is the same as that in the first embodiment, and although the description is repetitive, when wetting occurs due to dew condensation, it has the property that the moisture permeation amount increases several times as shown in the comparison table of FIG. 8. That is, in the initial state, the sealed space 66 serving as the drying chamber 51 is cooled in the refrigeration temperature range, there is no dew condensation, and the moisture permeability is small. However, when dew condensation starts on the moisture permeable membrane 73 of the humidity control window 71, the moisture permeation amount increases simultaneously, and the condensed moisture scatters into the refrigerator compartment. Therefore, although moisture condenses on the moisture permeable membrane 73, as a characteristic of the moisture permeable membrane 73 itself, the moisture permeation amount jumps up to about 5 times, so that moisture permeation proceeds smoothly and water droplets do not drip into the compartment and the permeation of moisture progresses.

[0152] While the sealed space 66 in the drying chamber 51 is heated by the heating means 76 and the temperature rises, and dew condensation occurs on the moisture permeable membrane 73, the heat of condensation is absorbed inside the moisture permeable membrane 73, and the heat of evaporation is taken away outside the moisture permeable membrane 73, so that the evaporation drying of the food material to be dried 67 continues while maintaining a relatively stable temperature near 5°C.

[0153] However, as the drying of the food material 67 to be dried progresses, the amount of moisture evaporated from the food material 67 to be dried decreases, the water vapor partial pressure value in the sealed space 66 of the drying processing chamber 51 becomes small, and when dew condensation on the moisture permeable membrane 73 disappears, the temperature of the moisture permeable membrane 73 will rise.

[0154] Since this moisture permeable membrane 73 material has a glass transition point Tg in the hydrophilic refrigeration temperature range of 0°C to 10°C, the moisture permeation amount is suppressed while the temperature is low. When the temperature of the moisture permeable membrane 73 rises above 20°C and enters the rubbery temperature region above the glass transition point Tg, the permeation of water vapor moisture increases. As shown by the curve in Fig. 7(A), the moisture permeation amount increases by more than three times at 10°C and 30°C.

[0155] Note that regarding the function of the moisture permeable membrane 73 in the state where the temperature of the sealed space 66 of the drying processing chamber 51 rises by the heating means 76 from the state where the refrigerating chamber 53 is stably cooled in the refrigeration temperature range, it is the same as that in the first embodiment and has been described in detail with reference to (1), (2), and (3) in Fig. 9, so it will be omitted.

[0156] Also, the factor for stabilizing the temperature of the moisture permeable membrane 73 is the change in the heat insulation property of the base cloth 74 to which the moisture permeable membrane 73 that becomes the moisture permeable membrane laminate 72 is attached, and its action and effect are also the same as those in the first embodiment, so the description will be omitted.

[0157] Therefore, the drying method using the moisture permeable membrane 73 of the present invention is not drying by forcibly blowing dried air onto the food material 67 to be dried, but drying by the water vapor partial pressure difference. Therefore, the cells of the food material 67 to be dried are dried while being wrapped by the water molecule film. In particular, the drying condition with a water vapor partial pressure difference of about 8 hPa is maintained from the initial stage of drying to the end point of drying, and this driving force is effective for drying. The force for drying increases due to the overlap of the upward air flow of air due to the temperature difference.

[0158] As described above, the present invention is not a drying method that blows dry cold air or hot air onto the food material 67 to be dried. Instead, it is a drying method that utilizes the water vapor partial pressure difference force through a moisture permeable membrane 73 capable of controlling temperature and humidity. As a result, the surface of the food material 67 to be dried has little color change and oxidative degradation is suppressed. This is an epoch-making drying function with little destruction of cell tissue and nutrients.

[0159] Next, the drying process ends when the heating means 76 is stopped by timer control. The sealed space 66 in the drying chamber 51 is gradually cooled by the cold air circulation wind 57 in the refrigerator compartment 53 and reaches the refrigeration temperature range. It can be left as it is for refrigerated storage, but it is recommended to take out the food material 67 to be dried at the end of drying, transfer it to another sealed container, and store it either refrigerated or frozen.

[0160] After the drying process, the dehydrated dried food material also has less cell destruction due to freezing. By devising the degree of dryness and the freezing temperature range, it is considered possible to preserve fresh vegetables with residual pectin and a crispy texture for a long time using this drying method.

[0161] Also, at the start of the drying process, when the moisture permeable membrane 73 condenses and significantly increases the moisture permeability, the moisture and free water adhering to the fresh food material quickly evaporate, enabling the moisture activity value of each food material 67 to be reached quickly, and also having the effect of suppressing the growth of miscellaneous bacteria.

[0162] Moreover, according to the refrigerator-freezer 50 with a drying function of the second embodiment, when the sealed space 66 in the drying chamber 51 is not used, as shown in FIG. 13, the drying chamber 51 can be removed and expanded for use as the refrigerator compartment 53. By turning the opening and closing mechanism shielding wall 62 over and stacking it on the bottom container shielding wall 61, it can be used as a storage shelf without taking it out.

Industrial Applicability

[0163] As described above, since the moisture-permeable membrane preferentially allows only moisture to pass through and does not allow other gases or odor components to pass through, by enhancing airtightness, it has been explained that the effect is to shut out odor components and prevent the transfer of odors to other foods and ice. In household refrigerators and freezers, it is necessary to store various foods together, so the effect of suppressing odor transfer is important.

[0164] However, a new drying method using a moisture-permeable membrane that dries the food to be dried to the dew point temperature at which water condenses once by the force of the water vapor partial pressure in the middle stage can prevent the discoloration of the food to be dried and prevent the oxidation of intracellular components and nutrients. Therefore, it can be expected to be effective even in large industrial refrigerators and freezers, and can also be used in that aspect.

[0165] In addition, although the configuration with the heating means attached to the refrigerator side has been described and explained as an embodiment, it is also possible to draw the power supply from the outside, assemble it as a single drying treatment chamber with a moisture-permeable membrane specification with a heating means, and store the drying treatment chamber in the refrigerators of various refrigerators and freezers for drying treatment. It is also possible to develop it into a product of a single drying treatment chamber that can be attached to existing household refrigerators and freezers as an option.

Explanation of Signs

[0166] 10, 50... Refrigerator-freezer, 11, 51... Drying treatment chamber, 12, 88... Upper ceiling shielding wall, 13, 73... Moisture permeable film, 14, 74... Base fabric, 15, 72... Moisture permeable film laminate, 16, 71... Humidity control window, 17, 62... Opening / closing mechanism shielding wall, 18... Storage shelf, 19, 67... Food to be dried, 20, 52... Freezer compartment, 21, 53... Refrigerator compartment, 22... Compressor, 23... Condenser, 24... Expansion valve, 25, 55... Evaporator (cooler), 26, 54... Refrigeration system, 27, 56... Cooling fan, 28, 57... Cold air circulation wind, 29, 58... Evaporator space, 30, 87... Cold air shielding wall, 31... Lower bottom surface, 32, 76... Heating means, 33, 79... Temperature detection and control means, 34... Thermal fuse, 35, 66... Sealed space, 36... Heat insulation door, 37, 83... Control device, 38, 80... Heat insulation box body, 39, 81... Freezer compartment door, 40, 82... Refrigerator compartment door, 41, 59... Duct work, 42, 60... Damper thermostat, 43, 84... Air inlet, 61... Bottom container shielding wall, 63... Under flange, 64... Upper flange, 65... Latch mechanism, 68... Upper storage shelf, 69... Lower storage shelf, 70... Bottom board, 75... Plane recess, 77... Ceramic plate, 78... PTC heater, 85... Heat insulation partition, 86... Convex surface

Claims

1. A drying processing chamber is provided in a refrigerator compartment which is cooled by circulating cold air which has been subjected to heat exchange in a cooler in the freezing temperature range and which has moisture removed as condensation or frost on the surface of the cooler, and which forms an enclosed space surrounded by the cold air shielding wall, and the enclosed space has a breathable storage shelf in which food materials to be dried can be placed, heating means for heating the food materials to be dried placed on the storage shelf to a predetermined temperature from the bottom, and a temperature detection control means for the enclosed space which controls the heating means, and a part of the cold air shielding wall is provided with an opening / closing mechanism shielding wall which allows the food materials to be dried or the storage shelf to be taken in and out, and a temperature sensor for detecting the temperature of the food materials to be dried that detects ... and an upper top shielding wall having a moisture control window provided with a moisture permeable membrane or moisture permeable membrane laminate which is a non-porous membrane through which no moisture components can move as a partition, wherein the heat insulating performance of the moisture permeable membrane or moisture permeable membrane laminate which serves as the partition is set to be the lowest compared to the other cold air shielding wall surfaces, thereby quickly cooling the moisture permeable membrane or moisture permeable membrane laminate to a refrigeration temperature, and utilizing the water vapor partial pressure difference between the drying processing chamber and the refrigeration chamber, heating at the predetermined temperature from the bottom portion by the heating means and the temperature detection control means causes moisture evaporated from the food material to be dried to condense and dew on the moisture permeable membrane or moisture permeable membrane laminate, thereby increasing the moisture permeability of the moisture permeable membrane or moisture permeable membrane laminate, thereby lowering the humidity in the drying processing chamber and accelerating the drying speed of the food material to be dried.

2. 2. The refrigerator-freezer with drying function according to claim 1, wherein the moisture-permeable membrane laminate is formed by laminating a hydrophilic moisture-permeable resin film serving as the moisture-permeable membrane onto a breathable base fabric, or by coating the base fabric with a hydrophilic moisture-permeable resin.

3. 3. The refrigerator-freezer with drying function according to claim 2, wherein the moisture-permeable membrane is a hydrophilic urethane-based resin film that is a non-porous membrane having a glass transition point Tg set in the vicinity of a refrigeration temperature range of 0° C. to 10° C. and that allows the movement of water molecules but is not breathable and does not allow the movement of liquid water, air, or odor components, the base fabric is a breathable woven fabric or nonwoven fabric, and the moisture-permeable membrane laminate is formed by bonding the base fabric and the moisture-permeable membrane via adhesive layers scattered at appropriate intervals.

Images