WO2019233816A1

WO2019233816A1 - A dryer and a drying method

Info

Publication number: WO2019233816A1
Application number: PCT/EP2019/063759
Authority: WO
Inventors: Mert GUNEY; Vasi Kadir Ertis; Haluk Karatas
Original assignee: Arcelik Anonim Sirketi
Priority date: 2018-06-05
Filing date: 2019-05-28
Publication date: 2019-12-12

Abstract

The present invention relates to a dryer (1) enabling food products to be freeze dried and to a drying method. The dryer (1) of the invention is characterized by a chamber (2) having at least one absorbent tube (22) containing at least one absorbent substance suitable to retain gaseous phase water molecules.

Description

A DRYER AND A DRYING METHOD

The present invention relates to a dryer enabling in particular food products to be freeze dried

Various methods are used to store food products for long periods of time. For example, preparing tomato paste out of tomatoes or pickles from gherkins are some of such methods. Canning is another frequently employed protection method. Another protection method is drying food products. Many food products, including meat products can thus be stored for long periods. In general, the drying process is based on the principle of evaporating the water in a food product by heating it for a long duration. Traditionally, sun is used as the heat source. However, colors of sun dried food products may change, various impurities may contaminate these food products as they remain outdoors during drying, and mold may develop thereon due to dew forming at nighttime. Even though most of these disadvantages can be eliminated by drying food products in an enclosed environment, this application fails to overcome the problem of color and aroma degradation in food products dried by means of a heat source.

A drying method enabling dried food products to maintain their color and aroma is freeze drying. Freeze drying process consists of three phases. The first phase is cooling a food product down to the triple point of water. The second phase is vacuuming the drying chamber to millibar levels and giving heat to the chamber in an amount as much as sublimation latent heat of water. The third phase is vacuuming the drying chamber to microbar levels and giving heat to the chamber until the temperature of the food product increases over 0°C. The water molecules remaining at the end of the first drying phase are thus removed from the food product. At the end of freeze drying process, water molecules in a food product are removed while maintaining color, taste and shape features and nutritional value of the food product. However, freeze drying is performed in industrial scales by means of considerably large-sized devices. Therefore, it is not possible for consumers to perform this process.

State of the art South Korean patent document no. KR20120011457 mentions a refrigerator capable of freeze drying.

State of the art Japanese patent document no. JP2000283627 mentions a refrigerator also capable of freeze drying.

None of the state of the art documents include a solution such as the one in the present invention.

The aim of the present invention is to realize a dryer enabling food products in particular to be freeze dried.

The dryer realized to achieve the aims of the present invention is illustrated in the accompanying drawings, wherein:
Figure 1: is a sectional view of an arrangement of the chamber.
Figure 2: is a view of the cooler group.

The elements in the figures are numbered individually and the correspondence of these numbers are given hereinafter.

Dryer
Chamber
21. Opening
22. Absorbent tube
Cooler group
31. Evaporator
32. Condenser
33. Capillary tube
34. Compressor
Chamber heater
Heater socket

The dryer (1) enabling in particular food products to be freeze dried, comprises in it most basic form,

at least one chamber (2) being suitable for placing therein food products desired to be dried and having at least one opening adapted to connect a vacuum tube suitable for applying vacuum therein, and at least one absorbent tube (22) containing at least one absorbent substance suitable for retaining gaseous phase water molecules,
at least one cooler group (3) for cooling the chamber (2) to a predetermined temperature,
at least one chamber heater (4) to give heat to the chamber (2) in an amount as much as the sublimation latent heat of solid phase water in the food product, and
at least one heater socket (5) adapted to give heat to the absorbent tube (22) in order to enable releasing the water molecules retained by the absorbent substance when the drying process is completed.

In it most basic form, the dryer (1) enabling in particular food products to be freeze dried, comprises at least one chamber (2) suitable for placing therein food products desired to be dried. At least one opening (21) is provided on the chamber (2), preferably on the lid of the chamber (2), adapted to connect a vacuum tube suitable for applying vacuum into the chamber (2). A vacuum tube is placed on said opening (21), enabling the chamber (2) to be vacuumed. At least one absorbent tube (22) is also provided in the chamber (2), containing at least one absorbent substance suitable for retaining gaseous phase water molecules. The cooler group (3) enables the chamber (2) to be cooled to a predetermined temperature. In a step of the drying process, it is required to give heat into the chamber (2) in an amount as much as the sublimation latent heat of the solid phase water in the food product. Said heat is emitted by the chamber heater (4). The chamber heater (4) may be disposed inside or outside the chamber (2). When the drying process is completed, to perform the next drying process, the water molecules retained by the absorbent substance should be released, i.e. absorbent substance should be regenerated. To that end, at least one heater socket (5) is provided, adapted to give heat to the absorbent tube (22).

The cooler group (3) comprises at least one evaporator (31), enabling drawing heat from the chamber (2). The evaporator (31) is preferably shaped as a tube helically advancing along the lateral surface of the chamber (2) in order to accelerate drawing heat therefrom. A refrigerant circulating in the cooler group (3) evaporates upon drawing heat from the chamber (2) via the evaporator (31) and reaches the condenser (32). The condenser (32) enables said refrigerant in gaseous phase to be converted back to liquid phase. The refrigerant is pressurized by the compressor (34). At least one capillary tube (33) is also provided in the cooler group (3), enabling changing pressure of the refrigerant. The capillary tube (33) has a smaller cross-sectional area than the other tubes conveying the refrigerant. The refrigerant reaching the capillary tube (33) enters into a smaller volume, and the volume of the refrigerant instantaneously expands at the outlet of the capillary tube (33). This enables the cooler group (3) to perform a more effective cooling.

After completion of a drying process, the water trapped by the absorbent substance should be removed to enable drying to be performed again. To that end, the chamber (2) is placed on the heater socket (5). The heater socket (5) is preferably shaped so as to enter into the absorbent tube (22) provided on the chamber (2). The heating process is started once the chamber (2) is placed on the heater socket (5), thereby evaporating the water entrapped in the absorbent substance, making the absorbent substance capable of retaining water again. This may be referred to as regeneration.

In an embodiment of the invention, the dryer (1) of the invention comprises at least one vacuum source for generating the vacuum required to be applied during the drying process.

An exemplification of a drying method executed by means of the dryer (1) of the invention is described hereinafter.

The materials desired to be frozen are placed in the chamber (2) and cooling process is started. The chamber (2) is cooled until the temperature therein reaches triple point of water. Once the temperature reaches triple point of water, the user connects the tube of a vacuum source to the opening (21) provided on the chamber (2). After creating vacuum within the chamber (2), heat is given to the chamber (2) in an amount as much as the sublimation latent heat of water by means of the chamber heater (4). In this stage, the solid phase water molecules in the food product sublimate and convert to gaseous phase. Gaseous phase water molecules are retained by the absorbent substance contained in the absorbent tube (22), thereby preventing water molecules from being reintroduced into the food product. In this stage, water molecules in the food product are drawn therefrom, and the drying process is thus completed. After releasing vacuum from within the chamber (2), the food products are removed from the chamber (2) and the chamber (2) is placed on the heater socket (5). Then the absorbent tube (22) is heated by means of said heater socket (5), regenerating the absorbent substance contained in the absorbent tube (22). The dryer (1) of the invention is now ready for a new drying process.

Claims

A dryer (1) enabling in particular food products to be freeze dried, comprising

- at least one chamber (2) suitable for placing therein food products desired to be dried, and

- at least one cooler group (3) for cooling the chamber (2) to a predetermined temperature, characterized by

- the chamber (2) having at least one opening (21) adapted to connect a vacuum tube suitable for applying vacuum therein, and at least one absorbent tube (22) comprising at least one absorbent substance suitable for retaining gaseous phase water molecules, and by

- at least one chamber heater (4) to give heat to the chamber (2) in an amount as much as the sublimation latent heat of solid phase water in the food product.
A dryer (1) according to claim 1, comprising at least one vacuum source for generating the vacuum required to be applied during the drying process.
A dryer (1) according to claim 1, comprising at least one heater socket (5) adapted to give heat to the absorbent tube (22) in order to enable releasing the water molecules retained by the absorbent substance when the drying process is completed.
A drying method suitable for operating a dryer (1) according to any one of the claims 1 to 3, characterized by the steps of

- placing the materials desired to be frozen in the chamber (2) and starting the cooling process,

- cooling the chamber (2) until the temperature therein reaches triple point of water,

- connecting a vacuum source to the opening (21) provided on the chamber (2) once the temperature reaches triple point of water,

- after creating vacuum within the chamber (2), giving heat to the chamber (2) in an amount as much as the sublimation latent heat of water by means of the chamber heater (4), and sublimating the solid phase water molecules in the food product, and

- retaining the gaseous phase water molecules by the absorbent substance contained in the absorbent tube (22).