JPH05137499A - Vacuum cooler provided with coldness-storing tank - Google Patents

Abstract

PURPOSE:To provide the subject vacuum cooler excellent in thermal efficiency and having a specified constitution whereby the facility is simplified. CONSTITUTION:This vacuum cooler is equipped with a coldness-storing tank 6 so that the refrigerator can be continuously operated. Thus, when the vacuum cooler is used for cooling vegetables, the refrigerator is utilized for cooling the cold trap 2. While the vegetable cooling is stopped, the refrigerator is exclusively utilized for making ice to circulate the brine containing fine particles of water. The coldness-storing tank 6 can store the ice-mixed brine at -5 deg.C only by introducing the warmed brine from cold trap 2 as well as the ice-mixed brine from brine cooler 4. In other words, the floating fine particles of ice are collected and stored in order, thus not only the sensible heat but also the latent heat which is about 80kcal/kg can be utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum cooling device,
A cool storage type that can be efficiently cooled by including a special brine cooler that produces a sharp fluid brine with fine fluidity and ice, and a cool storage tank for ice-mixed brine that has excellent followability to heat load fluctuations The present invention relates to a vacuum cooling device.

[0002]

2. Description of the Related Art Vegetables are still alive and active after harvest, but in order to maintain their freshness for a long time, it is important to suppress their respiratory action as soon as possible after harvest. The best way to control respiratory effects is to cool the vegetable temperature to near the freezing point. A vacuum cooling device is used for this cooling. By the way, when the pressure is 760 mmHg, water is 100 ° C,
22 ° C at 20 mmHg in vacuum state, 4 at 6 mmHg
It vaporizes at ℃ and takes away the latent heat of vaporization of about 600 kcal / kg.
The vacuum cooling device is a device that cools vegetables by vacuuming by utilizing the latent heat of vaporization of free water contained in the vegetables.
A typical non-heat storage type vacuum cooling device currently used is shown in FIG. That is, the vegetables are stored and sealed in the vacuum tank 1, and the vacuum pump 8 exhausts the vegetables. 20 in the vacuum tank
At mmHg, the free moisture of the vegetables having a product temperature of 22 ° C. starts to evaporate, the degree of vacuum increases, the evaporation is promoted, and the vegetables are cooled by the latent heat of evaporation. And 6 mmHg in the vacuum chamber
When reached, the vegetable temperature will reach 4 ° C. When water evaporated from vegetables becomes a gas, 1 liter of water is 6 mm under atmospheric pressure.
Since the volume of Hg is about 2 million times, it is technically difficult to exhaust with a vacuum pump. Therefore, a cold flap 2 is provided, and the cold flap 2 is cooled to around −5 ° C. by a brine cooler 4 to convert water vapor in the air exhausted from the vacuum tank 1 into water to drain the water, and only the air is supplied to the vacuum pump 8 Exhaust at. A brine cooler 4 and a cold trap 2 are used for this purpose.

[0003]

The cooling cycle of vacuum cooling is about 25 minutes, of which the evaporation time of vegetable water is about 17 minutes. Since a heat load is applied in this short time, a large capacity brine cooler is required. If the capacity of the electric device used is large, the electric charge, especially the basic charge, becomes expensive. The vegetable cooling system is used only for 5 months from June to October in one year, but you have to pay half of the basic fee even during the rest period. Therefore, the annual electricity bill is expensive and very uneconomical.

[0004]

The present inventor has found that the above-mentioned problems can be solved by installing a regenerator tank in a vacuum cooling device in consideration of economical efficiency of operating time of a refrigerator from the viewpoint of energy saving. In the past, a vacuum cooling device provided with a cold storage tank was proposed (Japanese Patent Application No. 59-207123 and Japanese Patent Application Laid-Open No. 61-86553). The apparatus is as shown in FIG. 3, and circulates through a vacuum pump 8 for vacuuming a vacuum tank 1 for vacuum cooling vegetables, a cold trap 2 for condensing water vapor evaporated from vegetables, and a cold trap. In a vegetable vacuum cooling device mainly composed of a brine cooler 4 for cooling brine, a compressor 3 of a refrigerant circulating in the brine cooler, and a condenser 5, the brine circulating in the cold trap 2 is about -5 ° C. At this time, about 60% of the water content is frozen, and a cold storage tank 6 is provided between the brine cooler 4 and the cold trap 2. During the vacuum cooling of the vegetables, the refrigerant from the condenser 5 is the refrigerant. While flowing into the brine cooler 4 through the three-way valve 14b, the brine flows from the brine cooler 4 to the cold trap 2, the cold storage tank 6, and the brine cooler 4, and then to the cold trap 2. It is arranged so as to condense the water vapor that evaporates from the vegetables, and when the vegetable vacuum cooling device is stopped, the brine is retained in the cold storage tank 6 and the three-way valve 14b is switched so that the refrigerant from the condenser 5 is stored in the cold storage tank 6. The vegetable vacuum cooling device is characterized in that it is piped so that about 60% of the water content of the brine flows to the cooling coil 17 installed in the container and freezes.

As a result of further research on a vacuum cooling device of this type, the present invention provides a brine cooler having a specific structure and a cold storage tank having a structure that facilitates the melting of ice, whereby The inventors have found that the problems can be solved more easily, and arrived at the present invention.
As mentioned above, one working step of vacuum cooling is about 30 minutes, but cooling of the cold trap is required for only about 17 minutes, and the working time per day is 5 hours. Therefore, when the vegetable cooling work is stopped, that is, when the vacuum cooling operation is not performed, the brine cooler is operated by using the night electric power with a low electricity rate, and a sharpet brine containing ice is exclusively produced, which is exclusively used in the cold storage tank. Frozen fine ice is floated and stored sequentially, and during vacuum cooling operation, brine of about 1 ° C introduced from the cold storage tank is cooled to about -5 ° C to -3 ° C by a brine cooler using normal power. It is sent to the upper cold trap and is used for cooling the cold trap. This makes it possible to efficiently use electric power and efficiently cool vegetables.

That is, according to the present invention, a vacuum pump 8 for vacuuming the vacuum tank 1 for vacuum cooling vegetables, a cold trap 2 for condensing water vapor evaporated from vegetables, and a brine circulating through the cold traps are cooled. The brine cooler 4, the compressor 3 and the condenser 5 for the refrigerant circulating in the brine cooler are the main components, and the brine cooler 4 and the cold trap 2 are provided.
In the vegetable vacuum cooling device in which the cold storage tank 6 is provided between the brine cooler 4 and the outer shell, the refrigerant is jetted to the jacket to supercool the cylinder 17, and the inner surface of the brine cooler 4 is cooled at high speed. It circulates to generate minute ice particles, and warmed brine from the cold trap 2 and cooling brine from the brine cooler 4 are introduced into the cold storage tank 6 by switching the brine three-way valve 14a. When the vegetables are cooled in vacuum, the refrigerant from the condenser 5 flows to the brine cooler 4 through the expansion valve 15, and
The brine (about 1 ° C) in the cold storage tank 6 is the brine circulation pump 1
1 is introduced into the brine cooler 4 at -5 ° C to -3 ° C
It becomes a sharpeput brine in which ice particles mixed with about 60% of the water content, which is cooled to a certain degree, is frozen, and then enters the cold trap 2 to exchange heat with vegetable steam to condense the steam and warm it (approximately 3 When the vegetable vacuum cooling is stopped, the brine three-way valve 14a is switched to switch from the cooler 4 to the cold storage tank 6 by flowing to the cold storage tank 6 and being piped to about 0 ° C. due to latent heat of melting of accumulated ice in the cold storage tank. Vacuum cooling with a cold storage tank, characterized in that a brine containing ice particles in which about 60% of the water content is mixed is introduced into the cold storage tank 6, and fine ice is sequentially accumulated from the upper portion to cool the brine. Equipment. For cooling the conventional cold trap, use calcium chloride, ethylene glycol, nybrine, etc. -1
It was cooled to around 0 ° C before use. Shimizu freezes and stores cold and uses latent heat, but brine does not freeze and use the latent heat, but uses sensible heat exclusively. However, when the brine is cooled while being rotated at a high speed in a cylinder having a jacket in which the refrigerant evaporates, the brine is immediately cooled and becomes supercooled, which has an extremely high heat transfer rate. This brine is sent to the center of the cylinder, and when the pressure drops, it freezes to form ice fine particles and become sharpet-like brine. In the present invention, this phenomenon is used as a trap and its latent heat is used.

An example of the vacuum cooling device of the present invention is shown in FIG. In FIG. 1, 1 is a vacuum tank, 2 is a cold trap, 3 is a compressor, 4 is a brine cooler, 5 is a condenser, and 6
Is a cold storage tank, 7 is a cooling tower, 8 is a vacuum pump, 9 is brine piping, 10 is refrigerant piping, 11 is brine circulation pump, 1
2 is a cooling water pump, 13 is a cooling water pipe, 14a is a brine three-way valve, 15 is an expansion valve, 16 is a refrigerant jacket, 17
Is a brine cooling cylinder, and W is a drainage drain.
When the device of the present invention is operated, the brine aqueous solution is sucked from the cold storage tank 6 at about 1 ° C. into the brine circulation pump 11.
It is pushed into the brine cooler 4. 1 ° C brine is-
It is cooled to 5 ° C., reaches the cold trap 2, and steam of 8 to 10 ° C. evaporated from vegetables is cooled to be replaced with water for dehumidification. The brine flowing in at about −5 ° C. exchanges heat with vegetable vapor to raise the temperature to 3 to 8 ° C., and is sprayed into the cold storage tank 6. The brine melts the stored ice and is cooled to about 0 ° C by its latent heat.

When the vacuum pump is stopped, that is, when the cooling of vegetables is stopped, the brine three-way valve 14a is switched to allow the cooling brine to flow from the brine cooler 4 to the cold storage tank 6 and circulate to exclusively produce a mixed solution of ice and brine. Then, the ice is floated and piled up one after another to store the ice and store the cold. For example, when a 40% aqueous solution of nai brine was circulated and cooled as a brine and the refrigerant evaporation temperature was adjusted to -10 ° C, an ice-mixed brine at -5 ° C could be obtained. Ice has a fine fluidity and can be pumped as it is to a cold trap or a cold storage tank to cool or store it. With this structure of the brine cooler, the water in the brine is supercooled in the solution to deposit ice particles, so that there is no concern that the water adheres to the cooling coil and reduces the cooling capacity.

Next, the cold storage tank 6 is not provided with a cooling coil, and brine is accumulated and fine ice is stored. During vacuum cooling of vegetables, brine cooled from the brine cooler 4 to about −5 ° C. is introduced into the cold trap,
What is heated to about 3 ° C. by heat exchange with the evaporated water of vegetables flows into the cold storage tank 6. On the other hand, when the vegetables are not vacuum-cooled at night, the brine three-way valve 14 is switched to introduce the ice-cooled brine cooled to about −5 ° C. in the brine cooler 4 into the cold storage tank 6. By repeating this process, fine ice with a low specific gravity floats on the top of the brine in the cold storage tank one after another, and the ice particles do not melt and form a collection of ice particles. The ice particles accumulated in the upper part of the cold storage tank have a large surface area and melt quickly. The 3 ° C. brine flowing from the cold trap melts the ice and loses the latent heat of 80 kcal / kg to 0 ° C. This 0 ° C. brine is sent to a brine cooler 4 by a brine circulation pump and cooled again to −5 ° C. by the cooler 4, directly to the cold trap 2 during the vacuum cooling operation, and directly to the cold storage tank 6 when stopped. Sent. As described above, the cold storage tank 6 of the present invention is not provided with the ice making refrigerant pipe by the cooling coil as in the previous invention, there is no circulation of the refrigerant to the cold storage tank, and the temperature rising brine is exclusively passed through the cold trap. In addition, the system is such that cooling brine from the brine cooler is introduced. That is, at night when vegetables are not cooled, ice is mixed with a brine cooler to generate brine, which is sent to a cold storage tank to store ice, and the latent heat of melting of fine ice in this cold storage tank is stored during vacuum cooling operation for cooling vegetables. Since it is used, the brine can be efficiently cooled by the brine cooler, and the equipment cost to the brine cooling coil 19 (see FIG. 3) in the cold storage tank 6 in the previously proposed vacuum cooling device and the icing on the cooling coil This makes it possible to reduce power consumption due to the stirring pump provided to prevent the vegetables from being cooled, and to cool vegetables efficiently at low cost.

The brine that can be used in the present invention requires brine at -3 to -5 ° C to cool the surface of the cold trap to about 0 ° C, so liquids having a freezing point of -5 to -7 ° C are brined. It is preferable to use as. For example, concentration 40
% Can be efficiently cooled by using an aqueous solution of nai brine. Freezing point of nyline 40% aqueous solution is -1
It has a specific gravity of 1.055 kg / 1 at 2 ° C., and is optimal for use as a brine of the device of the present invention. The same applies to an aqueous solution containing 20% or more ethylene glycol. or,
All those having the same action as described above can be used as brine. Due to this cold storage method, the capacity of the refrigerator becomes 1/2 or less of that of the conventional case, and accordingly, the cooling tower,
The auxiliary equipment such as a circulation pump has been reduced, and the brine agitation pump for avoiding ice accretion on the cooling coil installed in the cold storage tank is no longer necessary, and the equipment cost is reduced, especially the contract electricity charge is about 30 %, And the use of late-night power also saved about 25% in electricity bills. FIG. 4 is an explanatory diagram related to the heat storage operation. Vegetable cooling operation load is P ₁ Kcal /
If it is H, P ₂ Kcal / H that is ½ of P ₁ is operated at night, and if it is stored in a cold storage tank as ice, it will be P ₁ Kcal / H during vacuum cooling operation with a 1/2 capacity brine cooler. It can be seen that it can be processed and can be cooled with energy saving.

[0011]

[Operation] By installing a cold trap cooling cold storage tank in the vacuum cooling device, the refrigerator can be operated continuously. It is used for cold trap cooling when the vacuum device for vegetable cooling is operating, and ice is exclusively produced when the vegetable cooling work is stopped. Circulate a fine ice-cold brine. Further, the regenerator of the present invention only needs to introduce the warmed brine from the cold trap and the ice-mixed brine from the brine cooler.
By adopting a simple structure without a cooling coil in the cold storage tank, it is possible to store brine with an ice mixture of about -5 ° C in an energy-saving manner. Not to mention, the latent heat of fusion is about 80 kcal /
It has the effect that kg can be used.

[0012]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. A specific example of precooling vegetables using the vacuum cooling device with a regenerator according to the present invention will be described. In the apparatus of the present invention, (1) the refrigerant (Freon R-22) is compressed 3 → condenser 5 → expansion valve 1 both during cooling work of vegetables and during cooling stop.
5 → Brine cooler 4 → Compressor 3 flows to cool the brine, and the brine is cooled in the brine cooler to produce a cooled brine in which fine particles of ice are mixed. (2) Brine is a cold storage tank 6- (0 ° C) when working →
Circulation pump 11- (1 ° C) → brine cooler 4-(-
5 ° C.) → Cold trap 2- (3 to 8 ° C.) → Cool storage tank 6 (1 ° C.) → Brine cooler 4 flows. When the work is stopped, it flows from the brine cooler 4 to the cool storage tank 6 to store ice. (3) Specifications of vacuum cooling device Table 1 shows an example of the specifications of the device (precooling treatment amount, cooling capacity, available latent heat, etc.) when vegetables are precooled using the vacuum cooling device provided with the cold storage tank of the present invention. Shown in.

The non-heat storage type uses a brine cooler rated at 160 HP (120 KW) and the heat storage type has a rating of 60 HP (45 KW).

[0014]

[Table 1]

(4) The apparatus of the present invention and JP-A-61-1855.
Table 2 shows the characteristics of the No. 3 device.

[0016]

[Table 2]

As shown in Table 2, the capacity of the entire refrigerating apparatus is 58% in the apparatus of Japanese Patent Laid-Open No. 61-85553 as compared with the conventional apparatus, but in the present invention, the simplification of the regenerator tank apparatus results in It can be reduced to 56%, and by using a special brine cooler device, it is possible to prevent ice accretion on the cooling coil, etc., and it is also possible to make ice particles finer, making it easier to melt ice in the cold storage tank. It has the following characteristics and effects. (5) Facility cost and electricity rate The facility cost is slightly higher for the heat storage method, but the electricity rate is lower. That is, although the equipment cost of the cold storage tank must be added, the capacity of the brine cooler and the auxiliary equipment is halved, so the increase in the equipment cost is not so high. on the other hand,
The basic electricity charge is about 60%, and if you use an industrial heat storage adjustment contract (high-voltage power, 6KV) and use nighttime electricity, it will be cheaper, and you can pay 22% cheaper electricity yearly. .. Further, it can be used as it is in a differential pressure precooling device using brine as a cooling medium, a refrigerator for vegetable fruits such as apples, and the like.

[0018]

The present invention has the following effects and characteristics. 1. A special brine is used to cool the cold trap for vacuum cooling, a cold storage tank is attached to the vacuum cooling device, the brine cooler is operated both day and night, and a dedicated ice storage cycle for the cold storage tank is used at night. The cold trap is cooled by the sum of the latent heat of melting of ice in the tank and the cooling capacity of the brine cooler, which utilizes not only the sensible heat of the brine but also the latent heat of the ice. It uses energy. And it is possible to use late-night electric power for ice storage, and energy saving can be achieved. 2. Brine cooling is a method in which the brine in the cooling cylinder is swirled, and the brine that is supercooled at high speed freezes when the pressure drops and forms ice particles. This cold brine mixed with ice particles is introduced into a cold trap when cooling vegetables and into a cold storage tank when vegetables are stopped at night, and the ice is stored in the cold storage tank. It is possible to simplify the equipment. 3. The capacity of the brine cooler and auxiliary equipment is 1 /
Since it is 2, the entire facility will be smaller and the building will be smaller. 4. Even if the brine cooler fails, the ice-cooled brine in the cold storage tank can be used to start operation.

[Brief description of drawings]

FIG. 1 is a schematic view of a vacuum cooling device with a regenerator according to the present invention.

FIG. 2 is a schematic view of a conventional vacuum cooling device.

FIG. 3 is a schematic view of a vacuum cooling device described in JP-A-61-18653.

FIG. 4 is an explanatory diagram regarding an operating load related to heat storage operation.

[Explanation of symbols]

In the figure, 1 is a vacuum tank, 2 is a cold trap, 3 is a compressor, 4 is a brine cooler, 5 is a condenser, 6 is a cold storage tank, 1
Reference numeral 0 is a refrigerant pipe, 14a is a brine switching three-way valve, 15 is an expansion valve, 16 is a jacket, and 17 is a brine cooling cylinder.

Claims (1)

[Claims] 1. A vacuum pump 8 for vacuuming a vacuum tank 1 for vacuum-cooling vegetables, a cold trap 2 for condensing water vapor evaporated from vegetables, and a brine cooler 4 for cooling brine circulating in the cold trap. In the vegetable vacuum cooling device, the compressor 3 and the condenser 5 for the refrigerant circulating in the brine cooler are the main components, and the cold storage tank 6 is provided between the brine cooler 4 and the cold trap 2. The cooler 4 is composed of a super chiller with a special structure. The brine aqueous solution is circulated at high speed in a cooling cylinder to be supercooled, and ice particles are three-dimensionally precipitated in the solution. A pet is produced, and the warmed brine from the cold trap 2 and the cooling brine from the brine cooler 4 are introduced into the cold storage tank 6 by switching the three-way valve 14a. When the vegetables are cooled in vacuum, the refrigerant from the condenser 5 flows to the brine cooler 4 through the expansion valve 15, and the brine in the cold storage tank 6 is introduced to the brine cooler 4 by the brine circulation pump 11. It becomes a sharpet brine in which ice particles are mixed in which about 60% of the water content is cooled to about 5 ° C to -3 ° C, and then enters a cold trap 2 to exchange heat with vegetable steam to condense the steam. It is heated and flows to the cold storage tank 6,
In the cold storage tank, pipes are placed so that the latent heat of melting of the accumulated ice will bring the temperature to about 0 ° C. When the vegetable vacuum cooling is stopped, the brine three-way valve 14a is switched to allow the cooler 4 to cool the contained water to about 6%.
A vacuum cooling device with a cold storage tank, which is characterized in that a sharpet brine containing 0% of frozen ice particles is introduced into the cold storage tank 6 and is piped so as to successively accumulate and cool the fine ice as described above.