JP2000249441A - Vacuum cooling apparatus where cooling up to predetermined time is securely achieved - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely cool foods to be cooled up to a predetermined temperature in a vacuum cooling apparatus on which a chilling unit is provided. SOLUTION: A vacuum cooling apparatus is adapted such that it includes a processing tank 2 for accommodating foods to be cooled, a water ejector 1 or a water sealed vacuum pump being a vacuum generator apparatus for drawing the processing tank to vacuum, a vacuum piping 9 for connecting the processing tank and the vacuum generator apparatus, a circulation water tank 3 for storing circulation water therein used for the vacuum generator apparatus, a temperature sensor 6 for detecting circulation water tank, and a chilling unit 4 for cooling the circulation water, whereby the processing tank is drawn to vacuum to cool foods. in the apparatus, there is used a chilling unit for restricting circulation water temperature within a particular narrow range to reduce a difference between an upper limit value and a lower limit value of the circulation water temperature whereby cooling up to a predetermined temperature is securely achieved.

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 which can surely cool a food to be cooled to a predetermined temperature.

[0002]

2. Description of the Related Art As a device for cooling food, there is a vacuum cooling device. The vacuum cooling device stores the food to be cooled in a processing tank connected to a vacuum generator, such as a water ejector or a water ring vacuum pump, and reduces the moisture in the food by evacuating the processing tank. It evaporates and cools food. In the case of vacuum cooling, the final temperature of the food to be cooled is determined by the degree of pressure reduction in the treatment tank, and the higher the degree of pressure reduction, the lower the temperature can be cooled. In the case of a water ejector or a water ring vacuum pump, circulating water is used for depressurization, but the degree of depressurization is affected by the saturation pressure relative to the circulating water temperature, so the food after cooling is about 5 to 7 ° C higher than the circulating water temperature. The temperature becomes the limit temperature. Therefore, when it is necessary to cool the food to a lower temperature, a chilling unit is provided, and the final temperature of the food to be cooled is lowered by lowering the circulating water temperature by the chilling unit.

[0003] The chilling unit detects the circulating water temperature of the circulating water tank and operates so that the detected water temperature becomes a predetermined value. The compressor installed in the chilling unit operates immediately after the operation is stopped. Since the operation cannot be restarted, the start and stop of the operation cannot be repeated in a short time. Therefore, the chilling unit is provided with an operation prohibition time, and when the operation is stopped, the operation is not restarted during the operation prohibition time, so that the start and stop in a short time are not performed. . Therefore, the circulating water temperature may increase significantly during the operation prohibition time, and when the circulating water temperature greatly swings between the upper limit value and the lower limit value,
If the circulating water temperature at the end of vacuum cooling is high, the food may not be able to be cooled to a predetermined temperature. In addition, when the set temperature itself of the chilling unit is lowered in consideration of the swing width of the circulating water temperature, the upper limit temperature is lower but the lower limit temperature is also lower. There was also the problem of coming.

FIG. 3 shows an example of changes in circulating water temperature and food temperature at the end of vacuum cooling in a conventional vacuum cooling device. It is assumed that the chilling unit stops operating when the circulating water temperature is 3 ° C., starts operating after the lapse of the operation inhibition time T, and can cool the food to be cooled to + 5 ° C. of the circulating water temperature. During the vacuum cooling, at the point A where the circulating water temperature is increasing because the operation of the chilling unit is stopped, the circulating water temperature (for example, 6 ° C.) and the food temperature (for example, 11 ° C.) If the difference between the circulating water temperature and the food temperature does not exceed 5 ° C. from the point A to the end of the vacuum cooling, the food temperature cannot be lowered after the point A. Therefore, in this case, the vacuum cooling is ended without being able to cool the food to a predetermined temperature (for example, less than 10 ° C.).

[0005]

An object of the present invention is to make it possible to reliably cool a food to be cooled to a predetermined temperature in a vacuum cooling device provided with a chilling unit. is there.

[0006]

A processing tank for accommodating food to be cooled, a water ejector or a water ring vacuum pump as a vacuum generator for evacuating the processing tank, a vacuum pipe connecting the processing tank and the vacuum generator, A circulating water tank that stores the circulating water used for the vacuum generator, a temperature sensor that detects the temperature of the circulating water, and a chilling unit that cools the circulating water are provided.A vacuum that cools food by evacuating the processing tank In the cooling device, a chilling unit that keeps the circulating water temperature within a specific narrow range is used, and the difference between the upper limit value and the lower limit value of the circulating water temperature is reduced, so that cooling to a predetermined temperature can be reliably performed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of the configuration of a vacuum cooling device for implementing the present invention, and FIG. 2 is an explanatory diagram showing changes in food temperature and circulating water temperature in one embodiment of the present invention. The processing tank 2 for storing the food is connected to a vacuum generator by a vacuum pipe 9, and the food is put into the processing tank 2, and the processing tank 2 is evacuated to cool the food. The vacuum generator includes a water ejector 1 that sucks air in the treatment tank by water pressure, a circulating water tank 3 for storing circulating water, a circulating pipe 10 connecting the circulating water tank 3 and the water ejector 1, and a circulating water And a temperature sensor 6 for detecting the temperature of the circulating water in the circulating water tank 3.

The circulating water tank 3 is connected to a chilling unit 4 for cooling the circulating water, and a chiller pump 11 for sending the circulating water in the circulating water tank to the cooler 5 of the chilling unit 4 is provided. The chilling unit 4 includes a cooler 5 for removing heat from the circulating water, a compressor 13 for pressurizing the refrigerant, a condenser 12 and a fan 16 for releasing heat in the refrigerant, and a refrigerant for cooling the refrigerant cooled by the condenser 12 to the cooler 5. A cooling electromagnetic valve 14 for controlling the supply and a heating electromagnetic valve 15 for controlling the supply of the refrigerant pressurized by the compressor 13 to the cooler 5 directly without being sent to the condenser 12 are provided.

The vacuum cooling device cools the food by operating the vacuum generating device and the chilling unit 4, and is connected to the circulation pump 8, the chiller pump 11, the temperature sensor 6, and the chilling unit 4. The operation is controlled by the operation control device 7. The cooling of the food is performed by storing the food in the treatment tank 2 and sealing it, and operating the circulation pump 8 by the operation control device 7. When the circulating water is sent to the water ejector 1 and the air in the processing tank is sucked by the water ejector 1, the pressure in the processing tank decreases, and the moisture in the food is vaporized and the heat of vaporization is deprived. Is cooled. When a predetermined food cooling time has elapsed since the start of the operation of the circulation pump 8, the operation control device 7 stops the operations of the circulation pump 8, the chilling unit 4, and the chiller pump 11, and ends the cooling of the food.

The cooling of the food is 5 to 7 ° C. below the temperature of the circulating water.
Since it can only be performed to a temperature as high as possible, it is necessary to lower the temperature of the circulating water to cool the food to a lower temperature. Cooling of the circulating water is performed by sending the circulating water in the circulating water tank 3 to the cooler 5 of the chilling unit 4 by operating the chiller pump 11 and returning the circulating water cooled by the chilling unit 4 to the circulating water tank 3. .

Since the chilling unit 4 cannot repeatedly start and stop the compressor 13 in a short time, the compressor 13 is operated continuously. Until the temperature of the circulating water drops to the lower limit, the cooling electromagnetic valve 14 is opened, the heating electromagnetic valve 15 is closed, and the fan 16 is operated. When the refrigerant pressurized by the compressor 13 is supplied to the cooler 5 after being cooled by the condenser 12, the refrigerant is sent to the cooler 5 in order to remove surrounding heat when vaporized in the cooler 5. The circulating water is cooled.
When the circulating water temperature drops to the lower limit, the chilling unit 4 closes the cooling electromagnetic valve 14 and opens the heating electromagnetic valve 15 to change the flow path of the refrigerant.

When the refrigerant pressurized by the compressor 13 is sent to the cooler 5 without being cooled by the condenser 12,
The refrigerant sent to the cooler 5 only passes through the cooler 5 without cooling the circulating water in the cooler 5, but does not cool the circulating water. When the cooling of the circulating water in the chilling unit 4 is stopped, the temperature of the circulating water rises, and when the temperature of the circulating water rises to the upper limit, the heating electromagnetic valve 15 is closed again, the cooling electromagnetic valve 14 is opened, and the refrigerant flow path is opened. Change and restart circulating water cooling. By performing the above control, the cooling water circulation can be started and stopped at short intervals without starting and stopping the compressor 13, so that the difference between the upper limit value and the lower limit value is made smaller than usual. The temperature of the circulating water can be kept in a narrow specific temperature range.

FIG. 2 shows an example of changes in the temperature of circulating water and the temperature of food at the end of vacuum cooling in one embodiment. When the circulating water temperature is 3 ° C., the chilling unit performs the closing control of the cooling electromagnetic valve 14 and the opening control of the heating electromagnetic valve 15 to stop the cooling, and performs the opening and closing control of the cooling electromagnetic valve 14 at 4 ° C. It is set to start cooling. Further, it is assumed that the food temperature can be cooled to + 5 ° C. of the circulating water temperature, and the cooled food must be less than 10 ° C.

When the food temperature is high, the food temperature decreases in the same manner as in the conventional case shown in FIG. 3, and as in FIG. 3, the food temperature reaches 11 ° C. at the point A in FIG. However, since the circulating water temperature never rises above 4 ° C,
At the point A, the difference between the food temperature and the circulating water temperature is at least 7 ° C., and the food temperature can continue to decrease thereafter. Even if the circulating water temperature at the end of vacuum cooling is 4 ° C., which is the upper limit, the food temperature can be cooled to 9 ° C., which is 5 ° C. higher than the circulating water temperature. Can be cooled. Further, since the circulating water does not become lower than 3 ° C., the circulating water does not overcool.

If the difference between the upper limit value and the lower limit value of the circulating water temperature is too narrow, the refrigerant flow path is frequently changed. Since cooling of food becomes insufficient, about 1 ° C to 2 ° C is appropriate.

[0016]

According to the present invention, the food to be cooled can be reliably cooled to a predetermined temperature, and the circulating water is not excessively cooled, so that the circulating water does not freeze.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of the configuration of a vacuum cooling device that implements the present invention.

FIG. 2 is an explanatory diagram showing changes in food temperature and circulating water temperature in one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing changes in food temperature and circulating water temperature in a conventional case.

[Explanation of symbols]

 Reference Signs List 1 water ejector 2 treatment tank 3 circulating water tank 4 chilling unit 5 cooler 6 temperature sensor 7 operation control device 8 circulation pump 9 vacuum pipe 10 circulation pipe 11 chiller pump 12 condenser 13 compressor 14 cooling electromagnetic valve 15 heating electromagnetic valve 16 fan

Claims (2)

[Claims] 1. A processing tank for storing food to be cooled, a water ejector or a water-sealed vacuum pump as a vacuum generator for evacuating the processing tank, a vacuum pipe connecting the processing tank to the vacuum generator, and a vacuum generator. A circulating water tank for storing circulating water to be used, a temperature sensor for detecting the circulating water temperature, a chilling unit for cooling the circulating water are provided, and a vacuum cooling device for cooling food by evacuating the processing tank, A vacuum cooling device that uses a chilling unit that keeps the circulating water temperature within a specific narrow range and reduces the difference between the upper limit value and the lower limit value of the circulating water temperature so that cooling to a predetermined temperature can be performed reliably. 2. A vacuum cooling device according to claim 1, wherein the difference between the upper limit value and the lower limit value of the circulating water temperature is set within 2 ° C. A vacuum cooling device that reliably cools a food to be cooled to a predetermined temperature.