JP2012099263A - High-frequency induction heating method and device of heated object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the uniform and rapid thawing of a heated object such as a frozen food while suppressing partial electric field concentration on the surface of the heated object such as the frozen food.SOLUTION: In a high-frequency induction heating method in which the heated object is heated by electrodes disposed opposite to each other, at least one side heating electrode is constituted of an overall heating electrode and a partial heating electrode, and the overall heating and partial heating are simultaneously performed while controlling the electric field strength to the surface of the heated object and an inner surface part by controlling the amount of air gap in both electrodes.

Description

  The present invention relates to a high-frequency dielectric heating method and a high-frequency dielectric heating apparatus for an object to be heated, and more particularly to a heating method and an apparatus for heating an object by high-frequency dielectric heating capable of rapidly thawing frozen food.

  Conventionally, a method for thawing frozen food by high frequency dielectric heating has a high frequency dielectric heating electrode structure, and an air gap may occur due to irregularities on the surface of the frozen food to be heated, and an electric field may be concentrated on a part, resulting in thawing unevenness. There is a technical demand for uniform thawing while suppressing partial electric field concentration on the surface. As a solution to this, a method has been proposed in which the entire heating is performed while moving a partially heated spot electrode vertically and horizontally based on the detection output of the thawing state detection means during thawing (Patent Document 1). As another method, partial heating is performed by locally using a plate-shaped electrode that is smaller than the sandwiched surface of the object to be frozen, and then the entire surface is heated by gradually increasing the electrode area. A method has been proposed (Patent Document 2).

JP 2002-359064 A JP 2007-166952 A

Among the methods proposed above, the method of performing the whole heating while moving the spot electrode up and down and left and right is to move the spot electrode for partial thawing up and down and left and right while detecting the degree of thawing of frozen food. However, there is a problem that it takes a long time for thawing and rapid thawing is difficult. There is also a problem that drip is likely to occur when partially heated for a long time. On the other hand, the latter method also has a problem in that the high frequency dielectric heating characteristic that is characterized by rapid heating is not exhibited and rapid thawing cannot be performed because the method gradually spreads from partial heating to overall heating.
Accordingly, an object of the present invention is to provide a high-frequency dielectric heating method and apparatus that enables uniform and rapid thawing of food while suppressing partial electric field concentration on the food surface.

The high-frequency dielectric heating method of the present invention that solves the above-mentioned problems is a high-frequency dielectric heating method in which an object to be heated is heated with electrodes arranged opposite to each other, and at least one of the electrodes is an entire heating electrode and a partial heating electrode The total heating and the partial heating are performed simultaneously while adjusting the distance between the object to be heated, the total heating electrode, and at least one of the partial heating electrodes.
According to the present invention, the total heating and the partial heating can be performed simultaneously while adjusting the distance between the heated object, the whole heating electrode, and at least one of the partial heating electrodes. In the case of thawing of foods, partial simmering and browning can be prevented and thawing can be performed evenly, and the whole and partial heating can be performed simultaneously. It becomes.

  Further, in the invention, by adjusting the distance between the object to be heated and the electrode by an air gap, the high frequency energy to the object to be heated can be effectively controlled. For example, in the case of thawing frozen food, partial heating is performed. It is possible to effectively prevent the occurrence of drip generated when only one place is taken for a long time, and overheating such as baking and cooking. In addition, the object to be heated can be mounted on a mounting table made of a material having low dielectric loss and thermal conductivity and heated. Then, by applying the method of the present invention to heating of food, uniform thawing by rapid thawing is possible as compared with thawing by conventional high frequency dielectric heating.

The high-frequency dielectric heating apparatus of the present invention for carrying out the above-described high-frequency dielectric heating method is a heating apparatus that performs high-frequency dielectric heating of an object to be heated with electrodes opposed to each other, and at least one of the electrodes includes the whole heating electrode and the heating electrode. It consists of a partial heating electrode that can slide up and down in a through-hole provided in the whole heating electrode, the whole heating electrode being larger than the projected area of the object to be heated, and the partial heating electrode being larger than the projected area of the object to be heated And at least one of the overall heating electrode and the partial heating electrode is provided with means for adjusting the distance from the object to be heated.
By having the said structure, the high frequency dielectric heating method of Claim 1 can be reliably performed with a simple apparatus.

  In the present invention, since the whole heating electrode and the partial heating electrode are electrically connected, the whole heating and the partial heating can always be performed simultaneously, and the partial heating electrode does not hinder the whole heating. So quick thawing is possible. Further, by providing a plurality of partial heating electrodes on the whole heating electrode, the whole uniform heating can be performed more effectively without uneven heating corresponding to the complicated shape of the object to be heated. Furthermore, by making the other electrode arranged opposite to be an electrode that can follow the shape of the object to be heated, even an irregularly shaped object to be heated whose thickness is not uniform can be more uniformly heated. Moreover, by having an air chamber coupled to the whole heating electrode, the amount of air gap with respect to the object to be heated of the partial heating electrode can be easily adjusted. It is desirable to provide means for arranging the object to be heated on the mounting table and adjusting the distance from the object to be heated on the mounting table side.

  According to the high frequency dielectric heating method and high frequency dielectric heating apparatus of the present invention, at least one of the partial heating electrode smaller than the projected area of the object to be heated or the entire heating electrode larger than the projected area of the object to be heated, and the object to be heated By adjusting the air gap amount, it is possible to perform total heating and partial heating simultaneously while controlling the electric field strength to the surface and inside of the object to be heated, and rapid heating with reduced electric field concentration on the surface to be heated is possible. It is. Therefore, by applying the present invention to the thawing of frozen foods, rapid thawing is possible without causing unevenness of thawing even if the frozen food is irregular in shape as compared with the conventional one.

It is a schematic diagram of embodiment of the high frequency induction heating apparatus which concerns on this invention, and shows the state before the induction heating start. The state of the heating initial stage which made the air gap of the partial heating electrode in the apparatus shown in FIG. 1 small is shown. The state before the heating which made the air gap of the partial heating electrode large in the apparatus shown in FIG. 1 is shown. It is a schematic diagram of other embodiment of the high frequency induction heating apparatus which concerns on this invention, and shows the state before a dielectric heating start. It is principal part sectional drawing of embodiment of the upper electrode of the high frequency induction heating apparatus which concerns on this invention. It is a schematic diagram of other embodiment of the high frequency induction heating apparatus which concerns on this invention, and shows the state at the time of dielectric heating. It is a top view which shows the arrangement | positioning state of the partial heating electrode in the whole heating electrode in embodiment shown in FIG. 6 is a graph showing experimental results of Example 1 and Comparative Example 1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic explanatory view of an embodiment of a high-frequency dielectric heating device according to the present invention, and shows a state before heating, with the upper electrode still not lowered with the object to be heated placed on the mounting table. ing.
In the high-frequency dielectric heating device of the present invention, at least one of the lower electrode and the upper electrode arranged opposite each other is an overall heating electrode, and one of them is composed of a combination of an overall heating electrode and a partial heating electrode. Yes. In the high frequency dielectric heating apparatus 1 of the present embodiment, the lower electrode 2 disposed on the lower side on which the object to be heated is placed is a combination of the overall heating electrode 10 and the partial heating electrode 11, and the upper electrode 3 is the overall heating pin. It is an electrode. In FIG. 1, reference numeral 4 denotes a high-frequency transmitter, which is not shown, but is connected to a high-frequency power source and a high-frequency oscillation control circuit, and drives the entire heating electrode and the partial heating electrode constituting the upper electrode and the lower electrode. Each drive means and a control circuit for controlling it are provided.

  The lower electrode 2 is disposed in the chamber body 12 constituting the mounting table 15 on which the object to be heated M is mounted, and the entire heating electrode 10 and the entire heating electrode set so as to have a predetermined air gap with the mounting table. 1 or a plurality of partial heating electrodes 11 arranged so as to be movable up and down. The overall heating electrode 10 is at least larger than the projected area of the object to be heated M, and the partial heating electrode 11 has an area smaller than the projected area of the object to be heated. In this embodiment, the entire heating electrode 10 is a plate electrode plate. The partial heating electrode 11 is composed of rod-shaped electrode pins. The whole heating electrode 10 and the partial heating electrode 11 are both formed of a conductive material having excellent conductivity and thermal conductivity, and the chamber body 12 including the mounting table is formed of a non-conductive material.

  The partial heating electrode 11 is formed so that the vertical movement can be adjusted in a state where the partial heating electrode 11 is electrically connected to the whole heating electrode 10 with respect to the sliding hole 13 formed in the whole heating electrode. As a vertical drive means for the partial heating electrode 11, the chamber body 12 is divided vertically by the plate-like overall heating electrode 10, and the pressurized chambers 14a and 14b are formed in the vertical direction, and air is supplied to the air supply / exhaust ports 16a, By forming 16b so that the pressure in the chamber can be controlled, the axial position of the partial heating electrode 11 passing through the sliding hole 13 of the entire heating electrode 10 can be controlled. For example, in the state shown in FIG. 1 and FIG. 2, by setting the pressure Pb of the pressurizing chamber 14b higher than the pressure Pa of the pressurizing chamber 14a, the partial heating electrode 11 rises and the air gap amount L with respect to the mounting table (see FIG. 3). On the other hand, by evacuating the pressurizing chamber 14b and reducing the pressure Pb, the partial heating electrode 11 is lowered by its own weight and pressure difference, and the air gap amount can be increased. Thus, by controlling the pressure difference between the pressurizing chambers 14a and 14b, the position of the partial heating electrode 11 in the axial direction can be controlled, and the amount of air gap with the mounting table can be arbitrarily adjusted.

  Since the partial heating electrode 11 is always in conduction with the whole heating electrode 10, the partial heating and the whole heating are always performed simultaneously, and a strong high-frequency electric field is applied to the thick part of the object to be heated by the partial heating. While heating with high energy, the other portions are heated with weaker energy by the whole heating electrode having a large air gap amount, thereby realizing high-speed heating without heating unevenness. The partial heating electrode 11 also constitutes a part of the entire heating electrode. When the partial heating electrode 11 descends and the top surface reaches a surface substantially equal to the entire heating electrode 10, the partial heating electrode 11 is combined with the entire heating electrode. A high-frequency electric field having substantially the same level can be formed between the upper electrode 3 and the whole can be heated with a high-frequency electric field having a uniform intensity. According to the conventional apparatus, the high-frequency electric field by the partial heating electrode and the whole heating electrode is formed separately, and when the partial heating electrode is stopped, the whole heating electrode is shielded by the projected area occupied by the partial heating electrode, However, according to the present invention, such inconvenience does not occur, and the high frequency electric field can always be applied to the entire object to be heated while the intensity of the high frequency electric field can be partially adjusted.

In this embodiment, the upper electrode 3 is formed of an assembly 30 of heating pin electrodes.
As shown in detail in FIG. 5, the heating pin electrode assembly 30 can employ, for example, the one described in WO2009 / 008421 previously provided by the applicant of the present invention. A plurality of pin electrodes 31 that exert a functional or thermal action, a pin support base 32 as a conductive base that supports each pin electrode 31 in a slidable manner and serves as a power source or a heat source for the pin electrode 31, and a pin electrode 31 A pressure variable gas chamber body 33 that is displaced relative to the pin support base 32 is provided.

  The pin electrode 31 is an electrical or thermal contact with the pin head 35 that is in direct contact with the object to be heated and the pin head 35, and the amount of movement (stroke) of the pin electrode 31 relative to the pin support base 32 is reduced. It comprises a defining rod 36 and a pin cap 37 that defines the end position of the pin head 35 and functions as a stopper. The pin head 35 has, for example, a shape in which a hemispherical portion and a cylindrical portion are combined. The rod 36 has, for example, an elongated cylindrical shape, and one end thereof is screwed to the pin cap 37 at the end opposite to the pin head 35. ing. Further, the rod 36 is inserted into a through-hole 38 described later and serves as an electrical or thermal contact with the pin support base 32. As for the connection between the pin head 35 and the rod 36, a screw connection capable of exchanging the pin head according to the shape of the object to be heated is preferable, but it may be integrally formed by cutting or welding. The material of the pin head 35, the rod 36, and the pin cap 37 is a conductive material such as aluminum, copper, carbon, titanium, or platinum. The pin support base 32 is provided with a through hole 38 that is relatively displaced while the pin electrode 31 slides, and is provided separately for each pin electrode 31. The inner diameter of the through hole 38 is slightly larger than the outer diameter of the rod 36 of the pin electrode 31. As a result, each pin electrode 31 is independently displaced relative to the pin support base 32 in the axial direction while energizing or transferring heat to the pin support base 32, and can suitably follow the shape of the object to be heated.

  The driving of the pin electrode 31 can be easily realized by using an elastic tool such as a spring or rubber in addition to the pressure variable gas chamber. Further, since the pin support base 32 serves as a power source or a heat source for the pin electrode 31, a material having a conductivity and thermal conductivity equal to or higher than that of the pin electrode 31 is preferable. The shape of the pin support base 32 may be a flat plate or a composite shape having a curved surface. In the figure, reference numeral 39 denotes an electrical insulating / heat insulating material provided between the pin support base 32 and the pressure variable gas chamber body 33.

The pressure variable gas chamber body 33 includes a pressure variable gas chamber 34 for storing gas, a channel 29 serving as a gas flow path, and a gas port 28 connected to an external high-pressure gas source (compressor) or a (vacuum) pump. Become. The pressure of the pressure variable gas chamber 34 is adjusted by supplying or exhausting gas via the channel 29. Here, it pushed down by the pressure variable when the pressure P _in the gas chamber 34 is higher than the outside air P _out is the inlet gas pressure of the pin electrode 31 occurs pressure gradient pressure-variable gas chamber 34 at the outlet of the through hole 38 downward Relative displacement. On the other hand, if the pressure P _in the pressure-variable gas chamber 34 is lower than the outside air P _out, the pin electrode 31 occurs pressure gradient in the reverse direction is to be relatively displaced in the upward pushed by the outside air with it. As described above, the pin electrode 31 can be relatively displaced with respect to the pin support base 32 by adjusting the pressure of the pressure variable gas chamber 34. Further, by adjusting the pressure of the pressure variable gas chamber 34 in a state where the pin electrode 31 is in contact with the object to be heated, it is possible to change the pressure at which the pin electrode 31 contacts the object to be heated. Therefore, by adjusting the pressure of the pressure variable gas chamber 34 in a state where the pin electrode 31 is in contact with the object to be heated, the object to be heated can be heated and held by the plurality of pin electrodes 31. And the air gap disappears.

The dielectric heating device according to the present embodiment is configured as described above, and for example, even if the object to be heated is a frozen food having a non-uniform thickness, it can be thawed uniformly without thawing by high-speed thawing as follows. .
When a frozen food is thawed by a high-frequency dielectric heating device, the electric field concentrates on the surface of the food having a low impedance, so that rapid thawing with high energy causes browning on the surface, which requires a longer time than in the case of sterilization heating. In addition, when frozen foods are indeterminate with uneven thickness and not uniform height, thawing between the flat plate heating electrodes by high frequency dielectric heating is caused by the difference in the air gap between the electrode plate and the surface of the object to be heated. Since unevenness occurs, in order to eliminate unevenness in thawing, it has to be defrosted for a longer time, and rapid thawing was difficult as shown in a comparative example described later.

  In the present embodiment, as shown in FIG. 1, the pin electrode assembly is mounted on the mounting table 15 so that the thickest portion of the heated object M that is frozen food is positioned above the partial heating electrode 11. As shown in FIG. 2, by lowering the upper electrode 3 in which the pressure in the pressure variable gas chamber is adjusted so that a large number of 30 pin electrodes 31 are brought into contact with the surface of the object to be heated in contact with each other. A large number of pin electrodes follow the shape of the object to be heated and come into contact with the surface thereof, so that there is almost no air gap between the upper electrode and the object to be heated. On the other hand, the lower electrode is composed of a whole heating electrode and a partial heating electrode, but the high frequency power is always applied simultaneously from a single source. However, the entire heating electrode 10 has a predetermined air gap determined in advance with the mounting table 15, and the partial heating electrode 11 is configured such that the amount of air gap with the mounting table 15 can be arbitrarily adjusted. In the initial stage of heating, for example, by bringing the partial heating electrode 11 into contact with the mounting table and reducing the amount of air gap with the frozen food as much as possible, the thick portion located above the partial heating electrode is located at other locations. The portion where the entire heating electrode is opposed is heated at the same time in a state where the air gap amount is large, the high-frequency electric field is small and the energy given to the heated portion is small.

  And, if the partially heated electrode is heated in a state where it is in contact with the mounting table for a long time, if the frozen food is, for example, meat, there is a risk of drip coming out at that portion, resulting in quality deterioration. By turning off the air in the pressurizing chamber 14b after a lapse of time, the partial heating electrode is lowered to the lower position as shown in FIG. 3 to increase the air gap amount. When the partial heating electrode is in that state, high-frequency energy having substantially the same strength as the entire heating electrode is applied. Alternatively, it is also possible to intermittently change the partial heating electric field strength by repeatedly turning on and off the air in the pressurizing chamber 14b as necessary. In the above case, the partial electrode is controlled to be switched to two positions. However, the air gap amount of the partial heating electrode 11 may be increased stepwise by adjusting the pressure in the pressurizing chambers 14a and 14b. In this case, it is possible to reduce the heating energy by the partial heating electrode 11 step by step, to prevent overheating due to electric field concentration more effectively and to thaw the whole more uniformly. As described above, in this embodiment, the entire heating electrode and the partial heating electrode always act simultaneously to heat the entire object to be heated, and the air gap amounts of the entire heating electrode and the partial heating electrode can be relatively controlled. Therefore, it can be heated evenly.

FIG. 4 is a schematic diagram of another embodiment of the high-frequency dielectric heating device according to the present invention, and corresponds to the state shown in FIG. 1 of the embodiment.
This embodiment is different from the above-described embodiment in that both the entire heating electrode and the partial heating electrode constituting the lower electrode are configured such that the air gap amount can be adjusted. Portions common to the above-described embodiment are denoted by the same reference numerals as those of the above-described embodiment, and only differences will be described in detail.

  In this embodiment, the entire heating electrode 40 of the lower electrode is composed of a normal plate-shaped electrode plate, and the air gap between the mounting surface 15 and the mounting surface 15 can be adjusted by an appropriate driving means (not shown) in the chamber. It is installed so that it can be adjusted up and down. As a means for adjusting the vertical movement of the whole heating electrode 40, for example, the whole heating electrode is provided so as to be slidable by an appropriate guide mechanism so as to be partitioned into the sealed chamber body 12 up and down, and the upper pressurizing chamber 41a and the lower side are arranged. A pressurized chamber 41b is formed, and supply / exhaust ports 42a and 42b for pressurized air are provided in each chamber, and pressurized air is supplied and discharged through the supply / exhaust ports 42a and 42b. By moving up and down, the air gap with the object to be heated can be freely adjusted. The whole heating electrode vertical driving means is not particularly limited as long as the air heating gap between the whole heating electrode and the mounting surface 15 can be selected, and the driving means is not particularly limited. The electrode may be supported by a cylinder device capable of controlling the vertical driving amount, and the cylinder device may be driven by a control signal from the control means so that the air gap amount with the mounting surface 15 becomes a predetermined value.

On the other hand, the partial heating electrode 45 is formed so that the vertical movement can be adjusted in a state where the partial heating electrode 45 is electrically connected to the whole heating electrode with respect to the sliding hole formed in the whole heating electrode 40. As the vertical drive means of the partial heating electrode 45, for example, any means such as a cylinder device 46 can be adopted.
As described above, in the present embodiment, the air gap can be adjusted separately for the whole heating electrode and the partial heating electrode, and the whole heating and the partial heating can be performed simultaneously while separately adjusting the high-frequency electric field intensity by each electrode. For example, heating is started in a state where the air gap amount between the entire heating electrode and the partial heating electrode is adjusted in advance according to the size and type of the object to be heated, and ideally, the entire heating electrode is subsequently set in accordance with the preset control program. By simultaneously heating while controlling the air gap amount of the heating electrode 40 and the partial heating electrode 45, there is no heating unevenness in a more ideal state, and the thawing can be efficiently performed in a short time.

FIG. 6 shows still another embodiment of the high-frequency dielectric heating device according to the present invention. The same reference numerals are assigned to the same parts as in the above-described embodiment, and only the differences will be described. The main difference of the high-frequency dielectric heating device 50 in this embodiment from the above-described embodiment is that the partial heating electrode is composed of a plurality of heating pin electrodes, and each pin electrode is independently an air gap amount to the object to be heated. Is driven to be adjustable.
In the lower electrode 51 of this embodiment, a plurality of (seven in the present embodiment) partial heating electrodes 53 are held on a plate-like overall heating electrode 52 as shown in FIG. The partial heating electrode is constituted by a pin electrode, and a fitting hole 54 of the partial heating electrode formed in the whole heating electrode 52 constitutes a cylinder for driving the pin electrode up and down, and each fitting hole 54 has an individual pipe 55. The position where the upper end of the pin electrode is in contact with the mounting table 15 (that is, the amount of air gap is zero) and the whole heating electrode are connected to a pressurized air source via It can be displaced to a position that coincides with the upper surface of 52 (maximum air gap amount). Therefore, it is possible to defrost better by arbitrarily controlling the positions of the plurality of pin electrodes according to the shape of the object to be heated. The air gap of the pin electrode is adjusted, for example, by sequentially moving the pin electrode up and down at regular intervals so that only one pin electrode of the seventh embodiment of the pin electrode has the minimum air gap amount. The position of partial heating can be changed in order. Thereby, it becomes possible to heat a specific part intermittently with a partial electrode. In the present embodiment as well, as in the embodiment shown in FIG. 4, the air gap amount of the entire heating electrode as well as the partial heating electrode can be adjusted.

Although the embodiments of the high-frequency dielectric heating apparatus and method of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made within the scope of the technical idea.
For example, in each of the above embodiments, only one partial heating electrode is shown, but a plurality of partial heating electrodes are provided to selectively adjust the air gap amount according to the shape and size of the object to be heated. This is desirable because the whole can be thawed well and uniformly without heating unevenness. Further, the mechanism for adjusting the air gap amount of the entire heating electrode and the partial heating electrode is not limited to the pressurization mechanism or cylinder mechanism using air, but any means such as a combined use with a spring or a vertical movement mechanism using a servo motor. Can be adopted. Moreover, in the said embodiment, although the lower electrode was formed with the whole heating electrode and the partial heating electrode, conversely, it is also possible to form the upper electrode with the whole heating electrode and the partial heating electrode and to configure the lower electrode with the whole heating electrode. It is. Moreover, although the case where it applied to the defrosting of frozen food was demonstrated in the said embodiment, the high frequency dielectric heating method and apparatus of this invention are not only the defrosting of frozen food, but the normal heat processing of a to-be-heated material, or disinfection It can be suitably applied to heating for the purpose.

Example 1
Object to be heated: about 400 g of frozen pork block meat (size 140 x 100 x 60 mm),
However, the thickness is uneven and the maximum thickness is 60mm
Center temperature before start of thawing of heated object: -21.8 ° C, surface temperature: -8.6 ° C
The object to be heated was thawed under the following conditions with the high frequency dielectric heating apparatus of the embodiment shown in FIG.
Lower electrode size: Overall heating electrode 215 × 215 mm, partial heating electrode φ15 mm
Power supply frequency at decompression: 13.56 MHz
Power output during thawing: 200W
Air gap between the entire heating electrode and mounting table: 21 mm
Air gap between the partially heated electrode and the mounting table: 0 mm (120 seconds after starting), then 21 mm
During the thawing, the center temperature was measured using an optical fiber thermometer, and when the temperature reached −5 ° C., the thawing was completed. Arbitrary points were measured at five places on the upper surface temperature and five places on the lower surface temperature of the frozen pork block meat at the end of thawing. Each average surface temperature was 2.9 ° C on the upper side and 5.7 ° C on the lower side. According to this example, the center temperature reaches -5 ° C. with a thawing time of 3 minutes and a half, and it can be thawed in a very short time, and by adjusting the air gap by the partial heating electrode, there is no browning due to heat generation concentration on the pork surface, There was almost no generation | occurrence | production, and it was able to defrost well.

Comparative Example 1:
Object to be heated: 400g of frozen pork block meat of the same size and quality as in Example 1.
Center temperature before thawing start: −21.8 ° C., surface temperature: −8.6 ° C.
The object to be heated was thawed under the following conditions with a high-frequency dielectric heating apparatus in which the lower electrode was composed only of the entire heating electrode and the other upper electrode was composed of the pin electrode shown in FIG.
Electrode size: Whole heating electrode 215 × 215 mm,
Power supply frequency at decompression: 13.56 MHz
Power output during thawing: 200W
Air gap between the entire heating power supply and the mounting table: 21 mm
During the thawing, the thawing was completed when the center temperature reached -5 ° C. The results are shown in FIG. 8 together with Example 1. In this comparative example, the center temperature reached 5 ° C. with a thawing time of 12 minutes, and it took a long time that the thawing time was a little less than 4 times that of Example 1.

Example 2 :
Object to be heated: about 400g of frozen pork block meat (size 130 x 90 x 58mm)
However, the thickness is uneven and the maximum thickness is 58mm.
Center temperature before starting thawing of object to be heated: −22 ° C., surface temperature: −10 ° C.
The object to be heated was thawed under the following conditions with the high frequency dielectric heating apparatus of the embodiment shown in FIG.
Lower electrode size: Whole heating electrode 215 × 215 mm, partial heating electrode φ15 mm 7 Up / down switching drive is possible by air inflow / outflow from the lower part of each partial electrode, and the switching timing is every 8 seconds. The air gap distance between the entire heating electrode and the mounting table was 21 mm, and the air gap between the partial heating electrode and the mounting table was 0 mm when air was inflow and 21 mm when air was discharged.
Power supply frequency at decompression: 13.56 MHz
Power output during thawing: 35W
During the thawing, the center temperature was measured, and when the temperature reached −3 ° C., the thawing was completed. After thawing, the surface temperature of the frozen pork block meat was measured by thermography to calculate the surface average temperature. The upper average temperature was 7.2 ° C and the lower average temperature was 8.0 ° C. According to this example, the center temperature reached −3 ° C. without causing browning or drip due to heat generation concentration on the pork surface, and it was possible to defrost in a very short time. In this case, the difference between the upper average temperature and the lower average temperature was small compared to the case where the surface temperature was a single partial electrode, and the power output at the time of thawing was 35 W, and the entire surface could be defrosted substantially uniformly.

Comparative Example 2:
In the said Example 2, the lower electrode was comprised only with the whole heating electrode, and it thawed | decompressed on the following conditions.
Air gap between mounting tables: 21 mm
Power supply frequency at decompression: 13.56 MHz
Power output during thawing: 35W
During the thawing, the center temperature was measured, and when the temperature reached −3 ° C., the thawing was completed. After thawing, the surface temperature of the frozen pork block meat was measured by thermography to calculate the surface average temperature. The upper average temperature was 9.6 ° C., and the lower average temperature was 9.8 ° C. According to this comparative example, the surface temperature of the pork after thawing was higher than that of Example 2, and the thawing time to the central temperature of −3 ° C. was longer.

  The high-frequency dielectric heating device and dielectric heating device of the present invention can perform total heating and partial heating simultaneously while controlling the electric field strength to the surface and inner surface of the object to be heated, and the electric field concentration on the surface of the object to be heated. Can be rapidly thawed, and can be widely applied to the thawing of frozen foods in restaurants and homes and other industrial heating, and the industrial applicability is high.

DESCRIPTION OF SYMBOLS 1,50 High frequency dielectric heating apparatus 2,51 Lower electrode 3 Upper electrode 10,40,52 Whole heating electrode 11,45,53 Partial heating electrode 12 Chamber body 13,43 Sliding hole 14a, 14b, 41a, 41b Pressurization chamber 15 Mounting base 16a, 16b, 42a, 42b Pressurized air supply / exhaust port 17 Cylinder device 30 Pin electrode assembly 31 Pin electrode 32 Pin support base 33, 34 Pressure variable gas chamber 35 Pin head 36 Rod 37 Pin cap 38 Through hole 54 Fit Hole

Claims (10)

  A high-frequency dielectric heating method for heating an object to be heated with electrodes arranged opposite to each other, wherein at least one of the electrodes is composed of an entire heating electrode and a partial heating electrode, A high-frequency dielectric heating method comprising performing total heating and partial heating simultaneously while adjusting a distance from at least one of the partial heating electrodes.   The high frequency dielectric heating method according to claim 1, wherein a distance between the object to be heated and the electrode is adjusted by an air gap.   The high frequency dielectric heating method according to claim 1, wherein the object to be heated is placed on a mounting table.   The high-frequency dielectric heating according to any one of claims 1 to 3, wherein the object to be heated is food.   A heating apparatus for high-frequency dielectric heating of an object to be heated with electrodes arranged opposite to each other, wherein at least one of the electrodes is slidable up and down in a whole heating electrode and a through hole provided in the whole heating electrode The overall heating electrode is larger than the projected area of the object to be heated, and the partial heating electrode is smaller than the projected area of the object to be heated, and at least one of the overall heating electrode and the partial heating electrode Is provided with means for adjusting the distance from the object to be heated.   The high frequency dielectric heating apparatus according to claim 5, wherein the whole heating electrode and the partial heating electrode are electrically connected.   The high frequency dielectric heating apparatus according to claim 5 or 6, wherein the whole heating electrode is provided with a plurality of partial heating electrodes.   The high-frequency dielectric heating device according to any one of claims 5 to 7, wherein the other electrode arranged oppositely is an electrode capable of following the shape of the object to be heated.   The high-frequency dielectric heating device according to any one of claims 5 to 8, further comprising an air chamber coupled to the whole heating electrode.   The high frequency dielectric heating apparatus according to any one of claims 5 to 9, wherein means for arranging the object to be heated on a mounting table and adjusting a distance from the object to be heated are provided on the mounting table side.

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