JP2016200364A - Method for controlling over-cooling of aqueous solution, device for controlling over-cooling of aqueous solution, ice thermal storage device with aqueous solution, cooling device with aqueous solution and cooling system with aqueous solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling over-cooling of aqueous solution and a device for controlling over-cooling aqueous solution capable of over-cooling aqueous solution in an aqueous solution circuit to prevent occurrence of unconditional releasing of over-cooling through evaporation latent heat of refrigerant when a refrigerator is re-started and capable of restricting closing of a flow passage in the aqueous solution circuit along with freezing of aqueous solution.SOLUTION: This invention comprises: a step for calculating a concentration of aqueous solution on the basis of a liquid plane of aqueous solution in an ice thermal storage tank 34 arranged in an aqueous solution circuit 14 to receive ice slurry when a refrigerator is restarted, and estimating a freezing temperature of the aqueous solution on the basis of the calculated concentration of aqueous solution; a step for initial setting an evaporating temperature TE of the refrigerant in such a way that a temperature difference between the estimated freezing temperature of the aqueous solution and the evaporating temperature TE may become a specified value ΔT; and a step for changing-over from the estimated freezing temperature of the aqueous solution to a measured temperature of the ice slurry generated through releasing of the over-cooling, and adjusting the evaporating temperature TE of the refrigerant in such a way that a temperature difference between the measured temperature of the ice slurry and the evaporating temperature TE of the refrigerant may become the specified value ΔT.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aqueous solution supercooling control method, an aqueous solution supercooling control device, an aqueous solution ice heat storage device, an aqueous solution cooling device, and an aqueous solution cooling system, and more particularly, when a refrigerator is restarted, a refrigerant The latent heat of vaporization causes supercooling of the aqueous solution in the aqueous solution circuit so as not to cause unexpected supercooling release, and immediately after the supercooling starts, the aqueous solution is forcibly canceled to generate an ice slurry state. Aqueous solution supercooling control method and aqueous solution supercooling control device that can suppress blockage of the flow path in the aqueous solution circuit due to freezing of the aqueous solution, and the unexpected supercooling release due to the latent heat of vaporization of the refrigerant when the refrigerator is restarted The water solution in the aqueous solution circuit is supercooled so that it does not occur. The ice heat storage device that can suppress the blockage of the flow path in the aqueous solution circuit due to freezing of the aqueous solution while transporting the heat to the ice, and when the refrigerator is restarted, sudden cooling release is caused by the latent heat of vaporization of the refrigerant While supercooling the aqueous solution in the aqueous solution circuit so as not to occur, and immediately forcibly canceling the supercooling immediately after the start of supercooling, efficiently transporting heat in an ice slurry state, cooling the load side, When restarting a cooling device with an aqueous solution that can suppress the blockage of the flow path in the aqueous solution circuit due to freezing of the aqueous solution, and when the refrigerator is restarted, in the aqueous solution circuit so that unexpected supercooling release does not occur due to the latent heat of vaporization of the refrigerant While cooling the aqueous solution and cooling the load side by cooling the aqueous solution quickly and forcibly after the start of supercooling, quickly forcibly canceling the supercooling and efficiently transporting heat in the ice slurry state, A cooling system with an aqueous solution capable of suppressing blocking of the channel in an aqueous solution circuit with the solution freezing.

A device that generates a sherbet-like ice slurry in which ice strips are mixed with water by supercooling fresh water into supercooled water and then applying a shock such as vibration to the supercooled water to release the supercooled state. And methods have been provided for practical use. The ice slurry produced by such an apparatus and method has fluidity and is easy to convey, and can utilize the latent heat of ice, and thus has the advantage of good energy efficiency due to the effect of high-density heat conveyance. .
Therefore, as disclosed in, for example, Patent Literature 1 and Patent Literature 2, it is widely used as a cold source for a dynamic type ice storage device that supplies ice generated outside a thermal storage tank (ice storage tank) to the thermal storage tank. It is used for practical use.

  By the way, if the water for ice making is not pure water as described above, but if the brine is an aqueous solution in which a solute is dissolved in a solvent, the sensible heat and latent heat are large as in the case of using fresh water. If the medium is used, it is possible to send an aqueous solution at a sub-freezing temperature to the heat storage tank. it can.

  However, in conventional devices and methods that use fresh water as ice-making water, the freezing temperature does not change even if the amount of ice-making is large, but in the case of an aqueous solution, the frozen portion (solid phase) relative to the total amount of aqueous solution in the entire aqueous solution circuit When the ratio of the water content increases, the concentration of the unfrozen portion (liquid phase) increases, and when the concentration of the aqueous solution increases, the freezing point decreases.

  Therefore, when the aqueous solution is circulated through the aqueous solution circuit, the freezing point of the aqueous solution in the initial stage of ice making where the amount of ice stored in the heat storage tank is small, and the final stage of ice making where the amount of ice stored in the heat storage tank is large There is a significant temperature difference from the freezing point of the aqueous solution. That is, the evaporating temperature to be set in order to obtain stable supercooling is different between the initial stage of ice making and the final stage of ice making, and it is necessary to perform evaporating temperature control following changes in the freezing temperature.

  If the evaporating temperature of the refrigerant is set to a low temperature so that stable ice making is possible at the end of ice making, the difference between the freezing temperature and the evaporating temperature becomes large in the initial ice making stage, and the temperature of the heat transfer surface is frozen in the supercooling heat exchanger. Due to the fact that the temperature is too low, the supercooling heat exchanger cannot be maintained, and more specifically, at the point where the temperature of the inner surface of the pipe wall near the outlet of the supercooling heat exchanger is the lowest. There is a possibility that the possibility of freezing is increased, and the aqueous solution flow path of the supercooling heat exchanger is blocked by the freezing of the aqueous solution, thereby causing a problem that ice making stops.

  In this regard, Patent Document 3 solves such a problem, and the ice-making aqueous solution is supercooled by the supercooling heat exchanger by the latent heat of vaporization of the refrigerant supplied from the refrigerator, and then the aqueous solution is excessively cooled. In the ice storage method of generating ice slurry mixed with aqueous solution and ice strips by releasing the cooling state and storing the ice in the heat storage tank, the supercooling release sent to the heat storage tank by the ice slurry feed tube Disclosed is an ice making method by supercooling an aqueous solution so that the difference between the freezing temperature of the ice slurry immediately after and the refrigerant evaporation temperature in the supercooling heat exchanger is maintained at a constant value.

Patent Document 3 is a supercooling heat exchanger that supercools an aqueous solution for ice making by latent heat of vaporization of a refrigerant supplied from a refrigerator equipped with a compressor and a condenser, and is supercooled by the same heat exchanger. An ice core generator that generates ice slurry that releases the supercooled state of the aqueous solution and mixed with the aqueous solution and ice chips, and a heat storage tank that receives the ice slurry are provided in this order, and the aqueous solution for ice making from the load side is stored as heat. An aqueous solution feed pipe that is sent to the supercooling heat exchanger through the tank, and an ice slurry feed pipe that sends the cold water in the heat storage tank to the load side, and immediately after the supercooling release at the outlet of the supercooling heat exchanger An aqueous solution provided with a control circuit for adjusting the temperature of the refrigerant evaporation temperature so that the difference between the temperature of the ice slurry before being sent to the load side and the supercooled aqueous solution in the supercooling heat exchanger is maintained at a constant value. An ice making device by supercooling is disclosed.
With such a configuration, even if the concentration of the aqueous solution supplied to the supercooling heat exchanger fluctuates with the change in the amount of ice making in the heat storage tank, stable ice making can be performed. The possibility of problems such as freezing of the aqueous solution in the exchanger can be reduced.

However, Patent Document 3 has the following technical problems when the refrigerator is restarted.
More specifically, in the operation mode of the ice making device, for example, in order to contribute to the leveling of the electric load due to the use of nighttime power, the nighttime heat storage is performed, and the refrigerator is stopped using this heat storage during the daytime. In the case where the load side is cooled by circulating the aqueous solution between the heat storage tank and the load side, or when the heat storage amount due to nighttime heat storage is insufficient, the refrigerator is operated at the same time using the cold energy of the heat storage However, there is a case where the load side is cooled (hereinafter referred to as a chasing operation). In this case, the refrigerator may be operated or stopped depending on the load.

At that time, as the refrigerator is stopped, the ice in the heat storage tank is partially or completely defrosted and the freezing temperature (concentration) of the aqueous solution in the system is unknown by interrupting the generation of ice slurry. As a result, the supercooled state of the aqueous solution becomes an unsupercooled state again, so that the temperature of the ice slurry and the evaporation temperature before being sent to the load side immediately after the supercooling is released by the control circuit at the outlet of the ice nuclei generator are controlled. Adjust the refrigerant evaporation temperature in the supercooling heat exchanger so that the difference from the temperature of the cooling water solution is maintained at a constant value. Therefore, at the time of restart, it is unclear how many times the refrigerant evaporation temperature should be set.
In this case, at the time of restarting, if the refrigerant evaporating temperature is set immediately before stopping the refrigerator, in the initial stage of restarting, a part or all of the ice is defrosted and the freezing temperature of the aqueous solution is increased In this case, the difference between the freezing temperature and the evaporation temperature (strictly speaking, the temperature of the cooling heat transfer surface) becomes larger than a predetermined value, and the local supercooling degree of the aqueous solution is increased in the vicinity of the transfer surface, thereby In particular, there is a high possibility of freezing at the place where the temperature of the inner wall of the tube wall at the outlet of the supercooling heat exchanger is the lowest at the outlet of the supercooling heat exchanger. There is a possibility that the aqueous solution flow path of the exchanger is blocked and ice making stops.

Such a problem does not occur only in the ice making method and apparatus used in the ice heat storage device. For example, when the ice slurry is directly sent to a load side heat exchanger such as a heat exchanger for air conditioning to use cold heat. Is a similar problem.

JP 5-180467 JP 5-296503 A Japanese Patent No. 4623995

In view of the above technical problems, the purpose of the present invention is to supercool the aqueous solution in the aqueous solution circuit so that the unexpected supercooling release does not occur due to the latent heat of vaporization of the refrigerant when restarting the refrigerator. A method for controlling supercooling of an aqueous solution capable of suppressing clogging of the flow path in the aqueous solution circuit due to freezing of the aqueous solution while quickly forcibly releasing the supercooling immediately after the start of supercooling to generate an ice slurry state, and the aqueous solution The object is to provide a supercooling control device.
In view of the above technical problems, the purpose of the present invention is to supercool the aqueous solution in the aqueous solution circuit so that the unexpected supercooling release does not occur due to the latent heat of vaporization of the refrigerant when restarting the refrigerator. Aqueous solution that can forcibly cancel supercooling immediately after the start of supercooling, efficiently transport heat in an ice slurry state, and store the ice while suppressing the blockage of the flow path in the aqueous solution circuit due to aqueous solution freezing It is to provide an ice heat storage device.
In view of the above technical problems, the purpose of the present invention is to supercool the aqueous solution in the aqueous solution circuit so that the unexpected supercooling release does not occur due to the latent heat of vaporization of the refrigerant when restarting the refrigerator. Immediately after the supercooling starts, the supercooling is forcibly canceled and the heat is efficiently transported in the ice slurry state to cool the load side and blockage of the flow path in the aqueous solution circuit due to aqueous solution freezing can be suppressed. Another object is to provide a cooling device using an aqueous solution.
In view of the above technical problems, the purpose of the present invention is to supercool the aqueous solution in the aqueous solution circuit so that the unexpected supercooling release does not occur due to the latent heat of vaporization of the refrigerant when restarting the refrigerator. Immediately after the supercooling starts, the aqueous solution is forcibly released and the heat is efficiently transported in the ice slurry state, while cooling the ice heat storage and / or the load side, An object of the present invention is to provide a cooling system using an aqueous solution capable of suppressing clogging of a flow path.

In order to achieve the above object, the method for controlling supercooling of an aqueous solution of the present invention comprises:
Supercooling control of the aqueous solution that generates ice slurry by supercooling the aqueous solution in the aqueous solution circuit by the latent heat of vaporization of the refrigerant in the refrigerator and releasing the supercooled aqueous solution downstream from the supercooling part of the aqueous solution circuit An aqueous solution that adjusts the evaporation temperature of the refrigerant so that the temperature difference between the aqueous solution freezing temperature downstream of the supercooling section and the evaporation temperature of the refrigerant becomes a constant value ΔT until the target degree of supercooling is achieved. In the subcooling control method,
When restarting the refrigerator,
Calculating the concentration of the aqueous solution based on the level of the aqueous solution in the aqueous solution tank that receives the ice slurry provided in the aqueous solution circuit, and predicting the freezing temperature of the aqueous solution based on the calculated aqueous solution concentration;
A step of initially setting the evaporation temperature of the refrigerant so that the temperature difference between the predicted freezing temperature of the aqueous solution and the evaporation temperature of the refrigerant becomes a constant value ΔT; Supercool the aqueous solution to prevent release,
After the supercooling of the aqueous solution in the aqueous solution circuit starts, the forced supercooling release operation is performed while the supercooling degree approaches the target supercooling degree until the supercooling release of the aqueous solution is achieved downstream from the supercooling section. Repeating the cycle of determining whether or not the supercooling release has been achieved,
By switching from the predicted freezing temperature of the aqueous solution to the measurement temperature of the ice slurry generated by the release of the supercooling, the temperature difference between the measurement temperature of the ice slurry and the evaporation temperature of the refrigerant becomes the constant value ΔT. And adjusting the evaporation temperature and carrying out heat transport using ice slurry.

In the supercooling section of the aqueous solution circuit, the aqueous solution is set so that the temperature difference between the freezing temperature of the aqueous solution and the evaporation temperature of the refrigerant becomes a constant value ΔT so that the supercooling release does not occur until the target supercooling of the aqueous solution is achieved. In addition, once the target degree of supercooling is achieved, the supercooling is immediately released on the downstream side of the supercooling section to generate ice slurry.
In particular, when restarting the refrigerator, the ice in the aqueous solution tank generated by the ice slurry is thawed, and the freezing temperature of the aqueous solution is increased accordingly, so the freezing temperature of the aqueous solution is unknown, and the aqueous solution From the liquid level of the aqueous solution in the tank, the freezing temperature of the aqueous solution is predicted via the concentration of the aqueous solution, and the aqueous solution is set so that the temperature difference between the predicted freezing temperature of the aqueous solution and the evaporation temperature of the refrigerant becomes a constant value ΔT. Overcool.
Next, after the aqueous solution in the aqueous solution circuit starts to be supercooled, in a process in which the supercooling degree approaches the target supercooling degree until the supercooling release of the aqueous solution is achieved at a predetermined position downstream from the supercooling unit, After performing the supercooling release operation, the cycle for determining whether or not the supercooling release has been achieved is repeated.
After achieving the supercooling release of the aqueous solution, switch from the predicted freezing temperature of the aqueous solution to the measurement temperature of the ice slurry produced by the supercooling release, and the temperature difference between the ice slurry measurement temperature and the refrigerant evaporation temperature The ice slurry is generated while adjusting the evaporation temperature of the refrigerant so that the value becomes the constant value ΔT.
As described above, until the supercooling of the aqueous solution is achieved, the aqueous solution is cooled while preventing unexpected supercooling release.Once the supercooling of the aqueous solution starts, the evaporation temperature is determined by the exact freezing temperature of the aqueous solution. By adjusting the above, it is possible to suppress the supercooling of the aqueous solution downstream of the supercooling unit to generate an ice slurry state, and to suppress the blockage of the flow path in the aqueous solution circuit accompanying the freezing of the aqueous solution.

Further, the evaporation temperature initial setting step includes a temperature difference between a temperature increased by a predetermined temperature with respect to the predicted freezing temperature of the aqueous solution and the evaporation temperature of the refrigerant so that the supercooling is not canceled in the supercooling portion of the aqueous solution circuit. Is preferably set to be a constant value ΔT.
Furthermore, the supercooling release operation of the aqueous solution is performed by generating ice nuclei in the aqueous solution by the supercooling release unit provided downstream from the supercooling part of the aqueous solution circuit,
The step of repeating the supercooling release operation is performed after the temperature difference between the predicted freezing temperature of the aqueous solution and the aqueous solution temperature at the outlet of the supercooling releaser becomes a value sufficient to forcibly release the supercooling. It is good.

Furthermore, the achievement of the supercooling release of the aqueous solution is preferably determined by a temperature difference between the aqueous solution temperature upstream of the supercooling releaser and the aqueous solution temperature downstream of the supercooling releaser becoming a predetermined temperature.
In addition, the target supercooling degree of the aqueous solution is such that the supercooling release does not occur until the aqueous solution is supercooled in the supercooling unit, and after the supercooling of the aqueous solution starts, the aqueous solution is forced to be It should be set to a value sufficient to release the cooling.
In addition, the supercooling of the supercooled aqueous solution is canceled by an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
It is possible to repeat the step of operating and holding the ice nucleus generator until the temperature difference between the temperature of the aqueous solution upstream of the ice nucleus generator and the temperature of the aqueous solution downstream of the ice nucleus generator exceeds a predetermined value. Good.

Furthermore, the supercooling of the supercooled aqueous solution is canceled by an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
The temperature of the aqueous solution upstream of the ice nucleus generator decreases by a predetermined temperature until the temperature difference between the temperature of the aqueous solution upstream of the ice nucleus generator and the temperature of the aqueous solution downstream of the ice nucleus generator becomes a predetermined value or more. Each time, the stage of operating the ice nucleus generator may be repeated.
Furthermore, the supercooling of the supercooled aqueous solution is canceled by an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
After lowering the set initial evaporation temperature until the temperature difference between the aqueous solution temperature upstream of the ice nucleus generator and the aqueous solution temperature downstream of the ice nucleus generator exceeds a predetermined value, the ice nucleus is maintained. The step of operating the generator may be repeated.

To achieve the above object, the supercooling control device for an aqueous solution of the present invention comprises:
A supercooling heat exchanger that supercools the aqueous solution by the latent heat of vaporization of refrigerant supplied from a compressor and a refrigerator that includes a condenser, a supercooling release unit that releases the supercooling state of the aqueous solution, and an aqueous solution tank that receives the aqueous solution In this order, an aqueous solution circuit connected via an aqueous solution pipe,
And a control circuit that adjusts the refrigerant evaporation temperature according to the freezing temperature of the aqueous solution.
A predictive calculator for predicting the freezing temperature of the aqueous solution based on the liquid level of the aqueous solution in the aqueous solution tank;
Evaporating temperature adjusting means for adjusting the evaporating temperature of the refrigerant so that a temperature difference between the aqueous solution temperature between the supercooling releaser and the aqueous solution tank and the evaporating temperature of the refrigerant becomes a constant value ΔT;
A switching means for switching between the predicted freezing temperature of the aqueous solution and the measured temperature of the ice slurry generated by releasing the supercooling for the aqueous solution temperature between the supercooling releaser and the aqueous solution tank,
Temperature difference calculating means for calculating a temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the supercooling releaser and the aqueous solution temperature between the supercooling releaser and the aqueous solution tank; ,
The evaporating temperature adjusting means determines that the temperature difference between the freezing temperature of the aqueous solution predicted by the predictive calculator and the evaporating temperature of the refrigerant is a constant value ΔT until the temperature difference calculated by the temperature difference calculating means reaches a predetermined value. As described above, the ice slurry generated by the supercooling release from the freezing temperature of the aqueous solution predicted by the switching unit when the evaporation temperature of the refrigerant is adjusted and the temperature difference calculated by the temperature difference calculating unit becomes a predetermined value. The refrigerant evaporating temperature is adjusted so that the temperature difference between the measured temperature of the ice slurry generated by the supercooling release and the evaporating temperature of the refrigerant becomes a constant value ΔT.

Furthermore, the supercooling release device is an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
Until the temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the ice nucleus generator and the aqueous solution temperature between the ice nucleus generator and the aqueous solution tank reaches 0.5 ° C. or more, ice It is preferable to repeat the step of operating the nucleator for 30 seconds and holding for 1 minute.
The supercooling release device is an ice nucleus generator that transmits vibrations to the supercooled aqueous solution to generate ice nuclei in the aqueous solution.
Until the temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the ice nucleus generator and the aqueous solution temperature between the ice nucleus generator and the aqueous solution tank is 0.5 ° C. or more, Each time the temperature of the aqueous solution on the upstream side of the ice nucleus generator decreases by a predetermined temperature, the step of operating the ice nucleus generator for 30 seconds may be repeated.

Furthermore, the supercooling release device is an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
Set until the temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the ice nucleus generator and the aqueous solution temperature between the ice nucleus generator and the aqueous solution tank is 0.5 ° C. or more. After the initial evaporation temperature is lowered by 0.1 ° C. and held for 1 minute, the step of operating the ice nucleus generator for 20 seconds may be repeated.

In order to achieve the above object, the cooling device of the present invention comprises:
A cooling device comprising the supercooling control device for an aqueous solution according to any one of claims 9 to 12,
An ice slurry feed pipe that sends ice slurry generated by being overcooled by the supercool release unit to the load cooling side, and an aqueous solution return pipe that returns the aqueous solution from the load cooling side to the aqueous solution tank. Yes.

In order to achieve the above object, the cooling system of the present invention comprises:
A cooling system comprising the supercooling control device according to any one of claims 9 to 12,
The aqueous solution tank is an ice heat storage tank that receives the ice slurry generated by the supercool releaser and stores ice inside.
A load cooler is installed between the supercooling releaser and the ice heat storage tank,
A three-way switching valve between the supercooling releaser and the load cooler, and a load cooler bypass pipe connecting the three-way switching valve and the heat storage tank are provided,
By switching the three-way switching valve, the load cooler is cooled by ice slurry generated by the supercooling release by the supercooling releaser, or the supercooling release is performed via the load cooler bypass pipe It is possible to select whether to make ice in the heat storage tank with ice slurry generated by releasing the supercooling by the vessel.
Furthermore, the temperature difference between the temperature of the ice slurry after the release of supercooling and the refrigerant evaporation temperature in the supercooling heat exchanger is maintained at a constant value by controlling the evaporation pressure of the refrigerant in the supercooling heat exchanger. It is good.

In addition, a control valve whose opening degree is adjusted based on a control signal from the control circuit is provided in the middle of the refrigerant return pipe between the refrigerant outlet of the supercooling heat exchanger and the suction port of the compressor. It is preferable that the evaporation temperature of the refrigerant be adjusted by adjusting the opening of the control valve.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 shows a configuration diagram of the present cooling system.
The cooling system 10 includes a refrigeration circuit 12 and an aqueous solution circuit 14, and the refrigeration circuit 12 and the aqueous solution circuit 14 are used in an ice core melting heat exchanger 54 and a supercooling heat exchanger 24 (described later) for the refrigerant and the aqueous solution. Heat is exchanged between them.
In the refrigeration circuit 12, the compressor 28, the air-cooled condenser 30, the receiver 76, the ice core melting heat exchanger 54, the expansion valve 72, the supercooling heat exchanger 24, and the evaporation pressure adjusting valve 74 are arranged in this order in the refrigerant pipe 13. To form a circulation circuit. The refrigerant is, for example, R134a.
On the other hand, the aqueous solution circuit 14 is roughly composed of an ice nucleus melting part, a supercooling part 16, a supercooling release part 18, a load cooling part 20, and a heat storage part 22, and includes an ice heat storage tank 34, an aqueous solution liquid feed pump 92, an ice nucleus. The melting heat exchanger 54, the ice nucleus retention filter 56, the supercooling heat exchanger 24, the supercooling releaser 32 (ice nucleus generator 78), and the load cooler 20 are connected in this order via the aqueous solution pipe 36 and circulated. A circuit is formed.

The ice heat storage tank 34 receives the ice slurry generated by the supercool release unit 32 and stores ice therein, and the load cooler is interposed between the supercool release unit 32 and the ice heat storage tank 34. 20, a three-way switching valve 48 and a load cooler bypass pipe 60 connecting the three-way switching valve 48 and the ice heat storage tank 34 are provided between the supercooling releaser 32 and the load cooler 20. By switching the switching valve 48, the load cooler 20 is cooled by the ice slurry generated by the supercooling release by the supercooling releaser 32, or via the load cooler bypass pipe 60. It is possible to select whether ice is stored in the ice heat storage tank 34 by the ice slurry generated by releasing the supercooling.
The load cooler 20 is used, for example, as 0 ° C. air conditioning in a distribution refrigerator handling room (CA or CD indicates an opening for attaching the rear part of the truck).

As shown in FIGS. 2 and 3, since a propylene glycol (hereinafter referred to as PG) aqueous solution is used as the heat storage medium (hereinafter referred to as an aqueous solution), the concentration and the freezing temperature vary with the amount of ice stored. . The initial concentration of the aqueous solution is determined by the operating IPF range of the ice heat storage tank 34, the heat storage temperature (freezing temperature) at the end of heat radiation, and the physical properties of the aqueous solution. In this embodiment, it is assumed that the operation IPF of the ice heat storage tank 34 is 10 to 45%, and the heat storage temperature at the end of heat radiation (ice heat storage tank IPF 10%) is −4 ° C., and the initial aqueous solution calculated from this condition The concentration is about 17.7 wt% (freezing temperature ≒ -3.5 ° C), and the freezing temperature at the end of heat storage (ice heat storage tank 34IPF45%) is about -7.3 ° C.
In addition, the commercially available PG-based aqueous solution has a usable concentration range, but when used below the lower limit concentration, the added rust preventive or anticorrosive agent is diluted and the effect is insufficient. Therefore, additional adjustment may be required.

In FIG. 1, reference numeral 24 denotes a supercooling heat exchanger, and reference numeral 32 denotes a supercooling release unit having an ice core generator 78, and one end is connected to the lower part (liquid phase side) of the ice heat storage tank 34. An aqueous solution pipe 36 is connected to an aqueous solution inlet of the supercooling heat exchanger 24 via an aqueous solution feed pump 92, an ice nucleus melting heat exchanger 54 and an ice nucleus retention filter 56, and one end connected to the outlet. The other end of the pipe 36 is connected to the load cooler 20 via the supercool releaser 32.
The other end of the refrigerant pipe 13, one end of which is connected to the discharge port of the compressor 28, is connected to the supercooling heat exchanger via the air-cooled condenser 30, the liquid receiver 76, the ice nucleus melting heat exchanger 54 and the expansion valve 72. The refrigeration circuit 12 is configured by connecting the other end of the refrigerant pipe 13 connected to the refrigerant inlet 24 and having one end connected to the outlet to the suction port of the compressor 28.

  The aqueous solution sent from the ice heat storage tank 34 through the aqueous solution pipe 36 to the supercooling heat exchanger 24 by driving the aqueous solution feed pump 92 is cooled to a supercooled state 2 ° C. lower than the freezing temperature of the aqueous solution (supercooled). 2K), it is sent to the supercooling releaser 32.

  In the supercooling releaser 32, the supercooled aqueous solution is subjected to physical action such as vibration and impact by the ice nucleus generator 78 to release the supercooled state, and the aqueous solution (liquid phase) and ice strips are released. It becomes a sherbet-like ice slurry mixed with (solid phase) and is thermally transported to the load cooler 20 by the aqueous solution pipe 36 by a three-way switching valve 48 described later, or the ice heat storage tank 34 by the load cooler bypass pipe 60. To be stored in the ice heat storage tank 34.

  In the cooling system 10 of this embodiment, the aqueous solution corresponding to the temperature of the ice slurry, that is, the current concentration of the aqueous solution for ice making supplied to the supercooling heat exchanger 24, on the outlet side of the supercooling releaser 32 of the aqueous solution circuit 14. And a temperature sensor 96 for detecting the aqueous solution temperature on the inlet side of the supercooling releaser 32, and the supercooling heat exchanger 24 in the refrigerant pipe 13 of the refrigeration circuit 12. In the vicinity of the refrigerant outlet, a pressure sensor 94 for detecting the refrigerant pressure and an evaporating pressure adjusting valve 74 are provided in this order. These temperature sensors 98 and 96, the pressure sensor 94 and the evaporating pressure adjusting valve 74 are the temperature sensor and the pressure sensor. Is connected to a control circuit 82 that adjusts the opening degree of the evaporation pressure adjusting valve 74 based on the signal from.

That is, the temperature difference between the temperature of the ice slurry after the supercooling is released and the refrigerant evaporation temperature TE in the supercooling heat exchanger 24 is controlled to keep the refrigerant evaporation pressure in the supercooling heat exchanger 24 at a constant value. I have to.
More specifically, the opening degree is set in the middle of the refrigerant pipe 13 between the refrigerant outlet of the supercooling heat exchanger 24 and the suction port of the compressor 28 based on a control signal from the control circuit 82 (see FIG. 4). An evaporation pressure adjustment valve 74 to be adjusted is provided, and the evaporation temperature TE of the refrigerant is adjusted by adjusting the opening degree of the evaporation pressure adjustment valve 74.

  Specifically, the supercooling control device for the aqueous solution includes a supercooling heat exchanger 24 that supercools the aqueous solution by the latent heat of vaporization of the refrigerant supplied from the refrigerator that includes the compressor 28 and the air-cooled condenser 30, and a supercooling solution for the aqueous solution. The supercooling releaser 32 for releasing the cooling state and the ice heat storage tank 34 for receiving the aqueous solution are connected in this order via the aqueous solution pipe 36, and the refrigerant evaporation temperature TE according to the freezing temperature of the aqueous solution. And a control circuit 82 for adjusting.

As shown in FIG. 4, the control circuit 82 further predicts the aqueous solution freezing temperature based on the liquid level LS of the aqueous solution in the ice heat storage tank 34, the subcool release unit 32, and the three-way switching valve 48. Three-way switching between the evaporating temperature TE adjusting means 86 for adjusting the evaporating temperature TE of the refrigerant and the supercooling releaser 32 so that the temperature difference between the evaporating water temperature and the evaporating temperature TE of the refrigerant becomes a constant value ΔT1. Switching means 88 for switching between the predicted aqueous solution temperature between the valve 48 and the predicted temperature of the ice slurry generated by the release of supercooling, the supercooling heat exchanger 24 and the supercooling releaser Temperature difference calculating means 90 for calculating a temperature difference ΔT3 between the aqueous solution temperature between the supercooling releaser 32 and the three-way switching valve 48.

The evaporating temperature TE adjusting means 86 has a constant temperature difference between the freezing temperature of the aqueous solution predicted by the predictive calculator 84 and the evaporating temperature TE of the refrigerant until the temperature difference ΔT3 calculated by the temperature difference calculating means 90 reaches a predetermined value. The refrigerant evaporating temperature TE is adjusted so as to have a value ΔT1, and when the temperature difference calculated by the temperature difference calculating means 90 reaches a predetermined value, it is generated by releasing the supercooling from the freezing temperature of the aqueous solution predicted by the switching means 88. The refrigerant evaporation temperature TE is adjusted so that the temperature difference between the measurement temperature of the ice slurry generated by the release of the supercooling and the evaporation temperature TE of the refrigerant becomes a constant value ΔT1. Like to do. The constant value ΔT1 is 3K, for example.

ΔT1 is preferably set in accordance with the type of aqueous solution to be used or the type of the supercooling heat exchanger. For example, in the case of an alcohol-based aqueous solution, it is difficult to maintain a supercooled state by a supercooling heat exchanger, and unexpected supercooling may be canceled. Therefore, ΔT1 should be smaller than 3K. In the case of a propylene glycol-based or ethylene glycol-based aqueous solution, it is easy to maintain a supercooled state by a supercooling heat exchanger, and it is unlikely to cause unexpected supercooling release. Therefore, even if ΔT1 is made larger than 3K Good.

Also, for example, in the case of a shell and tube heat exchanger, the heat exchange efficiency is relatively low, and therefore, the possibility of unexpected supercooling cancellation is low, so ΔT1 may be larger than 3K. In the case of a plate heat exchanger, the heat exchange efficiency is relatively high, and therefore, unexpected supercooling may be canceled. Therefore, ΔT1 should be smaller than 3K.
Thus, in the supercooling heat exchanger, when heat exchange is performed under a condition where the heat flux is relatively large, ΔT1 is preferably set to be smaller than 3K in order to prevent unexpected overcooling cancellation.

  More specifically, when the amount of ice stored in the ice heat storage tank 34 increases and the concentration of the aqueous solution supplied to the supercooling heat exchanger 24 for ice making increases, the freezing temperature of the aqueous solution decreases, and therefore immediately after the supercooling is released. Since the difference between the ice slurry temperature and the refrigerant evaporation temperature TE becomes small, the evaporation pressure is reduced, that is, the refrigerant evaporation temperature TE is lowered by increasing the opening of the evaporation pressure adjusting valve 74.

  On the other hand, when the amount of ice stored in the ice heat storage tank 34 decreases and the concentration of the aqueous solution supplied to the supercooling heat exchanger 24 for ice making decreases, the freezing temperature of the aqueous solution rises, and thus the ice slurry immediately after the supercooling is released. Since the difference between the temperature and the refrigerant evaporation temperature TE becomes large, the evaporation pressure is increased, that is, the refrigerant evaporation temperature TE is increased by reducing the opening of the evaporation pressure adjusting valve 74.

  As described above, the refrigerant evaporation temperature TE is adjusted in accordance with the change in the freezing temperature of the aqueous solution (the temperature of the ice slurry immediately after the release of the supercooling), whereby the supercooled aqueous solution at the aqueous solution outlet of the supercooling heat exchanger 24 is adjusted. The temperature, that is, the minimum temperature of the aqueous solution also changes corresponding to the refrigerant evaporation temperature TE, and is controlled so that the difference between the freezing temperature of the aqueous solution and the refrigerant evaporation temperature TE in the supercooling heat exchanger 24 is constant.

The supercooling releaser 32 includes an ice core generator 78 that transmits vibrations to the supercooled aqueous solution to generate ice nuclei in the aqueous solution, and is provided between the supercooling heat exchanger 24 and the supercooling releaser 32. The supercooling releaser 32 is operated for 30 seconds and held for 1 minute until the temperature difference between the aqueous solution temperature and the aqueous solution temperature between the supercooling releaser 32 and the three-way switching valve 48 becomes 0.5 ° C. or more. Repeat the steps.
As a modification, the temperature difference between the aqueous solution temperature between the supercooling heat exchanger 24 and the supercooling releaser 32 and the aqueous solution temperature between the supercooling releaser 32 and the three-way valve 48 is 0.5 ° C. or more. Until the temperature of the aqueous solution on the upstream side of the supercooling releaser 32 decreases by a predetermined temperature, the step of operating the supercooling releaser 32 for 30 seconds may be repeated. The predetermined temperature is, for example, 0.1 ° C.
As another modification, the temperature difference between the aqueous solution temperature between the supercooling heat exchanger 24 and the supercooling releaser 32 and the aqueous solution temperature between the supercooling releaser 32 and the three-way valve 48 is 0.5 ° C. Until the above is reached, after the set initial evaporation temperature TE is lowered by 0.1 ° C. and held for 1 minute, the stage of operating the supercooling releaser 32 for 20 seconds may be repeated.
In any case, once supercooling of the aqueous solution is started, it is preferable to generate ice slurry by forcibly releasing supercooling as soon as possible.

This cooling system 10 is configured by unifying two operation patterns of “heat storage (ice storage) operation” and “heat radiation (chase) operation”, both of which are based on the operation of the compressor 28 and ice by ice slurry. Heat is transferred to the heat storage tank 34 or the load cooler 20 and is switched only by selecting the flow direction of the three-way switching valve 48.
The operation flow starting from the ice heat storage tank 34 is shown in the following (1) to (5).
(1) The aqueous solution taken from the ice heat storage tank 34 is sent to the ice nucleus melting heat exchanger 54. The water intake 68 is provided with double metal meshes 68 having different mesh sizes at intervals of about several hundred millimeters to suppress the outflow of ice crystals that hinder supercooling in the supercooling heat exchanger 24. . In addition, the intake water temperature is substantially the same as the freezing temperature corresponding to the concentration of the aqueous solution at that time during the heat storage operation, and is about 2K higher than this during the heat dissipation operation.

(2) During the heat storage operation, the aqueous solution is heated to the freezing temperature + 0.5K by the ice nucleus melting heat exchanger 54.
This is to melt the fine ice crystals (ice nuclei) remaining in the aqueous solution and hinder supercooling, and has the effect of preventing the blockage of the flow path due to freezing in the supercooling heat exchanger 24. Achieved.
The ice core removal filter 56 has a role of retaining the ice crystals until the size of the ice crystals becomes a certain value or less, and the ice crystals that have passed through the ice crystals have a temperature difference of 0.5 K before reaching the supercooling heat exchanger 24. Can be completely melted.

As the heat source, sensible heat in the high-temperature and high-pressure supercooling region in the refrigeration cycle is used, and the amount of added heat is offset by an increase in refrigeration capacity (refrigeration effect), so no energy loss occurs.
Even during heat dissipation operation or heat storage operation, if the intake water temperature is higher than the freezing temperature + 0.5K, the flow path of the high-temperature and high-pressure refrigerant liquid (see Fig. 1) is switched to exchange the ice nucleation heat. By bypassing the vessel 54, the aqueous solution temperature before cooling may not be unnecessarily increased. This achieves the effect of preventing the supercooling stability from being impaired by suppressing the increase in size of the supercooling heat exchanger 24 due to an increase in the amount of cooling heat and increasing the cooling temperature range.

(3) The supercooled aqueous solution is released from supercooling in the supercooling releaser 32, and becomes ice slurry containing ice crystals corresponding to the amount of heat of the supercooling.
In the initial stage after the system is started, since there are no ice crystals serving as ice nuclei in the supercooling releaser 32, spontaneous supercooling release in the supercooling releaser 32 does not occur. For this reason, when the aqueous solution at the outlet of the supercooling heat exchanger 24 reaches a predetermined degree of supercooling, the ice core generator 78 of the supercooling releaser 32 is vibrated to forcibly cancel the supercooling. Urging. When the supercooling is released, the temperature of the aqueous ice slurry (hereinafter referred to as ice slurry) rises to the freezing temperature. This is detected by the temperature sensor 98 and the supercool releaser 32 stops. Once the ice crystals are present in the supercooling releaser 32, the ice crystals become nuclei thereafter, and spontaneously supercooling continuously as soon as the aqueous solution flows into the supercooling releaser 32. Release continues.

(4) As shown in FIG. 6 to FIG. 9, the generated ice slurry is loaded into the ice heat storage tank 34 when the heat storage operation is being performed, or is loaded when the heat dissipation operation is being performed, by switching the flow path of the three-way switching valve 48. It is sent to the cooler 20.
More specifically, FIGS. 6 and 7 show the case where the ice heat storage operation is performed, and FIGS. 8 and 9 show the case where the cooling operation is performed. In FIG. 6 and FIG. From the ice heat storage tank 34 to the supercooling heat exchanger 24 via the ice core melting heat exchanger 54 and the ice core removal filter 56 by the cold water transfer pump 92, it is supercooled by the latent heat of vaporization of the refrigerant and supercooled. In the releaser 32, the supercooling is released and ice slurry is formed, which is sent to the ice heat storage tank 34 via the load cooler bypass pipe 60 by the three-way switching valve 48, whereas in FIGS. 6 is similar to that in FIGS. 6 and 7 in that the supercooling is released from the ice heat storage tank 34 in the supercooling releaser 32, and ice slurry is formed. And scattered It returned to the ice heat storage tank 34 through the nozzle 62.
The difference between FIG. 6 and FIG. 7 is that FIG. 6 is the operation before the achievement of the supercooling release immediately after restarting the refrigerator. For this reason, the temperature difference between the freezing temperature of the aqueous solution and the evaporation temperature TE of the refrigerant is The predicted temperature (T1 ′) is used as the freezing temperature of the aqueous solution to vary the target evaporation temperature TE (opening of the evaporation pressure adjusting valve) so as to be kept at a predetermined value (eg, 3K), FIG. 7 shows the operation after the supercooling release is achieved, and the measured temperature (T1) is used as the freezing temperature of the aqueous solution. The difference between FIG. 8 and FIG. 9 is the same as the difference between FIG. 6 and FIG. It is.
In this cooling system, since ice slurry is used as the cooling heat medium during the heat radiation operation, not only the conveyance power is reduced by the high-density cooling and heat conveyance, but also the temperature on the heat medium side of the load cooler 20 is kept low. Therefore, the heat exchange efficiency is improved, and the load cooler 20 can be reduced in size.
(5) The ice slurry sent to the load cooler 20 receives an air conditioning load, the ice crystals melt, the sensible heat rises slightly, and flows into the ice heat storage tank 34. A water spray 62 is provided at the return port, and is arranged so that the aqueous solution is uniformly sprinkled into the ice heat storage tank 34. Reference numeral 64 is a circulation system for increasing the amount of water sprayed. Water is taken from the ice heat storage tank 34 by the ice melting promotion pump 66 and joined with the aqueous solution from the aqueous solution pipe 36 to be sprinkled.
If the ice storage is biased in the ice storage tank 34, the aqueous solution tends to flow to a route with little ice storage (low water resistance) and short circuit to the water intake without sufficient heat exchange with the ice storage. There arises a problem that predetermined heat radiation cannot be obtained. In such a case, it is preferable to add a function of performing partial watering by appropriate judgment.

The cooling system 10 always detects or predicts the freezing temperature of the aqueous solution and the evaporation temperature TE of the refrigerant to calculate the temperature difference between the two, and this value is maintained at a predetermined value (eg, 3K). In addition, feedback control is performed to vary the target evaporation temperature TE (opening of the evaporation pressure adjusting valve).
That is, in the supercooling control method of the aqueous solution, the aqueous solution in the aqueous solution circuit 14 is supercooled by the latent heat of vaporization of the refrigerant by the refrigerator, and the supercooled aqueous solution is released from the supercooling portion 16 downstream of the aqueous solution circuit 14. This is a method for controlling the supercooling of the aqueous solution that generates ice slurry and transports heat, and the aqueous solution freezing temperature downstream of the supercooling unit 16 and the evaporation temperature TE of the refrigerant until the target supercooling degree is achieved. The evaporation temperature TE of the refrigerant is adjusted so that the temperature difference becomes a constant value ΔT.
Note that the target supercooling degree of the aqueous solution is such that the supercooling release does not occur until the aqueous solution is supercooled in the supercooling unit 16, and the aqueous solution is forced to flow downstream from the supercooling unit 16 after the supercooling of the aqueous solution starts. Set to a value that is sufficient to release overcooling. The target degree of supercooling is, for example, about 1K to 2K.

More specifically, as shown in FIG. 5, when the refrigerator is restarted, the aqueous solution concentration is determined based on the liquid level LS of the aqueous solution in the ice heat storage tank 34 that receives the ice slurry provided in the aqueous solution circuit 14. The freezing temperature of the aqueous solution is predicted based on the calculated aqueous solution concentration (Step 1). More specifically, in the ice heat storage tank 34, the liquid level tends to decrease as the amount of heat storage (ice) increases. Using this relationship, the liquid level sensor 80 provided on the side of the ice heat storage tank 34 determines the amount of heat storage (ice), predicts the approximate freezing temperature (T1 '), and controls the evaporation temperature TE. The initial evaporation temperature to be performed is determined (step 2 and step 3). Next, the temperature sensors 96 and 98 and the pressure sensor 94 start measuring the supercooling releaser outlet side aqueous solution temperature T1, the supercooling releaser inlet side aqueous solution temperature T3, and the refrigerant evaporation pressure PE (step 4), and then store the ice heat. The operation is selected from the cooling operation (step 5), the three-way switching valve 48 is switched accordingly (step 6), the aqueous solution feed pump 92 is activated (step 7), and the refrigerator is turned on (step 7). Step 8).

Next, the evaporation temperature TE is adjusted by adjusting the evaporation pressure of the refrigerant so that the temperature difference between the predicted freezing temperature T1 ′ of the aqueous solution and the evaporation temperature TE of the refrigerant becomes a constant value ΔT1, and thereby the aqueous solution Unexpected overcool release is prevented from occurring in the supercooling section 16 of the circuit 14 (step 9 and step 10). At that time, after starting up the apparatus, the temperature slightly higher than the predicted freezing temperature (eg, 0.3K) is regarded as the temporary freezing temperature (T1 ′) taking into account the accuracy of the prediction on the safe side, and the evaporation temperature TE is set as the target. Cooling operation controlled to the value is performed. As a result, unintentional release of supercooling from the supercooling part of the aqueous solution circuit 14 is prevented from occurring reliably.

Subsequently, after the temperature difference between the predicted freezing temperature of the aqueous solution and the aqueous solution temperature at the outlet of the supercooling releaser 32 becomes a value ΔT2 sufficient to forcibly cancel the supercooling, the supercooling release operation is repeated ( Step 11 and Step 12). ΔT2 is, for example, 0.5K. In the case of an alcohol-based aqueous solution, ΔT2 may be set smaller than 0.5K as the timing for forcibly canceling the supercooling.
The supercooling release operation of the aqueous solution is performed by generating ice nuclei in the aqueous solution by the supercooling releaser 32 provided downstream of the supercooling unit 16 of the aqueous solution circuit 14, and the supercooling releaser 32 is vibrated. However, if the outlet temperature of the supercooling releaser 32 does not rise, it is determined that the supercooling release has not been achieved, and the same operation is performed with an appropriate interval (time interval or supercooling degree expanded). Repeat until the supercooling is released.
Then, after the aqueous solution in the aqueous solution circuit 14 starts supercooling, forced subcooling is performed in the process in which the supercooling degree approaches the target supercooling degree until the supercooling release of the aqueous solution is achieved downstream from the supercooling unit 16. After performing the release operation, a cycle for determining whether or not the supercooling release is achieved is repeated (steps 13 to 14).

The achievement of the supercooling release of the aqueous solution is determined by the difference in temperature between the measured aqueous solution temperature at the outlet of the supercooling releaser 32 and the measured aqueous solution temperature at the inlet of the supercooling releaser 32 being ΔT3. ΔT3 is, for example, 0.5K.
Next, when the supercooling is released in the supercooling releaser 32, the temperature of the generated ice slurry rises to the freezing temperature, so that the accurate freezing temperature can be detected at the outlet of the supercooling releaser 32, and thereafter , Switching to higher-precision evaporation temperature TE control using T1 (step 15).
That is, switching from the predicted freezing temperature of the aqueous solution to the measured temperature of the ice slurry generated by the release of supercooling, so that the temperature difference between the measured temperature of the ice slurry and the evaporation temperature TE of the refrigerant becomes a constant value ΔT1. While adjusting the evaporation temperature TE of the refrigerant, heat transport using ice slurry is performed (steps 16 and 17).

After the ice making operation is started, the aqueous solution is concentrated as the amount of heat storage increases, and the freezing temperature is lowered. By such feedback control of the evaporation temperature TE, the measured temperature of the ice slurry and the evaporation temperature TE of the refrigerant In the state where the temperature difference is maintained at ΔT1, supercooled ice making is continuously performed. When the freezing temperature corresponding to the end of heat storage (full ice) is reached, the device is stopped. With the above evaporation temperature TE control, it is possible to continue stable supercooled ice making using an aqueous solution.

FIG. 10 shows an example of actual measurement data of the aqueous solution supercooling ice making operation by the cooling system 10 of the present embodiment.
According to FIG. 10, changes over time of the supercooling heat exchanger inlet aqueous solution temperature, the supercooling heat exchanger outlet aqueous solution temperature, the supercooling release outlet aqueous solution temperature, and the supercooling heat exchanger refrigerant evaporation temperature TE after the supercooling release. It is shown.
When the temperature of the aqueous solution at the outlet of the supercooling releaser rises almost stepwise, the release of supercooling is started and the aqueous solution is concentrated as the amount of heat storage (ice) increases. The evaporation temperature TE is controlled so that the temperature difference between the supercooling releaser outlet aqueous solution temperature and the supercooling heat exchanger refrigerant evaporation temperature TE becomes ΔT1 as the freezing temperature decreases. Recognize.

According to the above configuration, in the supercooling section 16 of the aqueous solution circuit 14, the temperature between the freezing temperature of the aqueous solution and the evaporation temperature TE of the refrigerant is prevented so that the unexpected supercooling release does not occur until the supercooling of the aqueous solution is achieved. The aqueous solution is cooled so that the difference becomes a constant value ΔT1, and once the target degree of supercooling is achieved, the supercooling is immediately released downstream of the supercooling unit 16 to generate ice slurry.

In particular, when the refrigerator is restarted, the ice in the ice heat storage tank 34 generated by the ice slurry has melted, and the freezing temperature of the aqueous solution has increased accordingly, so the freezing temperature of the aqueous solution is unknown. The freezing temperature of the aqueous solution is predicted from the liquid level of the aqueous solution in the ice heat storage tank 34 via the concentration of the aqueous solution, and the temperature difference between the predicted freezing temperature of the aqueous solution and the evaporation temperature TE of the refrigerant is a constant value ΔT1. The aqueous solution is supercooled so that
Then, after the aqueous solution in the aqueous solution circuit 14 starts supercooling, forced subcooling is performed in the process in which the supercooling degree approaches the target supercooling degree until the supercooling release of the aqueous solution is achieved downstream from the supercooling unit 16. After performing the release operation, the cycle for determining whether or not the supercooling release is achieved is repeated.

After achieving the supercooling release of the aqueous solution, switch from the predicted freezing temperature of the aqueous solution to the measurement temperature of the ice slurry generated by the supercooling release, and the temperature between the ice slurry measurement temperature and the refrigerant evaporation temperature TE Ice slurry is generated while adjusting the evaporation temperature TE of the refrigerant so that the difference becomes a constant value ΔT1.
As described above, until the supercooling of the aqueous solution is achieved, the aqueous solution is cooled while preventing unexpected supercooling release.Once the supercooling of the aqueous solution starts, the evaporation temperature is determined by the exact freezing temperature of the aqueous solution. By adjusting the TE, it is possible to release the supercooling downstream of the supercooling unit and generate an ice slurry state, while suppressing the blockage of the flow path in the aqueous solution circuit 14 due to the aqueous solution freezing.

The embodiments of the present invention have been described in detail above, but various modifications or changes can be made by those skilled in the art without departing from the scope of the present invention.
For example, in this embodiment, the load cooling operation and the ice heat storage operation have been described as performing heat transport in the form of an ice slurry by forcibly releasing the supercooling of the aqueous solution. In operation, heat transport may be carried out in the form of cold water rather than in the form of ice slurry. In that case, in the aqueous solution circuit, the refrigerator may be turned off and the cold water may be heat transported to the load cooler 20, or between the load cooler 20 and the ice heat storage tank 34, independently of the aqueous solution circuit. In addition, a cold water feed pipe from the ice heat storage tank 34 to the load cooler 20 and a cold water return pipe from the load cooler 20 to the ice heat storage tank 34 are provided, and then the refrigerator is turned off to supply cold water to the load cooler 20. And the ice heat storage tank 34 may be circulated.

For example, in this embodiment, in both the load cooling operation and the ice heat storage operation, heat transfer is performed in the form of ice slurry by forcibly releasing the supercooling of the aqueous solution, and in the aqueous solution circuit, the refrigerator is switched by switching with a three-way switching valve. Although the load cooling operation and the ice heat storage operation are selectively performed in the on state, the so-called chasing operation is described. However, the load cooler 20 and the ice heat storage tank 34 are not limited to the aqueous solution circuit. The load cooling operation and the ice heat storage operation may be simultaneously performed by arranging in parallel and adjusting the flow rate distribution of the aqueous solution.
For example, in the present embodiment, the ice heat storage operation has been described as performing heat transport in the form of ice slurry by forcibly releasing the supercooling of the aqueous solution, but the present invention is not limited thereto, for example, without performing ice heat storage. The present invention is also applicable to the case where ice slurry is directly sent to a load-side heat exchanger such as a heat exchanger for air conditioning to use cold energy.

For example, in the present embodiment, the cooling system 10 has been described as the case where the cooling operation and the heat storage operation are performed in the form of heat transport using ice slurry. As long as smooth supercooling release is achieved and ice slurry is generated when forced supercooling is cancelled, the generated ice slurry can be used as it is, or an efficient heat transport mode using ice slurry. As long as this is utilized, the heat transfer mode using ice slurry may be utilized for either the cooling operation or the heat storage operation.

1 is an overall configuration diagram of an aqueous cooling system 10 according to an embodiment of the present invention. It is a table | surface which shows the relationship between IPF of the ice thermal storage tank 34 of the cooling system 10 by the aqueous solution concerning embodiment of this invention, aqueous solution density | concentration, and freezing temperature. It is a graph which shows the relationship of IPF, aqueous solution density | concentration, and freezing temperature of the ice thermal storage tank 34 of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is a block diagram of the control circuit of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is a flowchart which shows the supercooling control flow of the aqueous solution of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is a figure similar to FIG. 1 which shows the cooling operation 1 of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is a figure similar to FIG. 1 which shows the cooling operation 2 of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is a figure similar to FIG. 1 which shows the ice thermal storage driving | operation 1 of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is a figure similar to FIG. 1 which shows the ice thermal storage driving | operation 2 of the cooling system 10 by the aqueous solution concerning embodiment of this invention. It is the graph which shows the ice making operation actual measurement data by the cooling system 10 by the aqueous solution concerning embodiment of this invention, time is shown on a horizontal axis, and temperature is shown on the vertical axis | shaft.

T1 supercooling releaser outlet side aqueous solution temperature T1 'predicted aqueous solution freezing temperature T3 supercooling releaser inlet side aqueous solution temperature ΔT1 T1' (T1) -TE
ΔT2 T1'-T1
ΔT3 T3 -T1
PE Refrigerant vapor pressure TE Refrigerant vapor temperature LS Aqueous solution level 10 Cooling system 12 Refrigeration circuit 14 Aqueous circuit 16 Supercooling unit 18 Supercooling release unit 20 Load cooling unit 22 Thermal storage unit 24 Supercooling heat exchanger 26 Supercooling control device 28 Compression Machine 30 Air-cooled condenser 32 Supercooling release unit 34 Ice storage tank 36 Aqueous solution piping 48 Three-way switching valve 54 Ice nucleation heat exchanger 56 Ice nucleation filter 60 Load cooler bypass pipe 62 Spray nozzle 64 Bypass pipe 66 De-icing promotion pump 68 Wire mesh 70 Adjusting valve 72 Expansion valve 74 Evaporating pressure adjusting valve 76 Receiving device 78 Ice core generator 80 Liquid level meter 82 Control circuit 84 Prediction computing unit 86 Evaporating temperature adjusting means 88 Switching means 90 Temperature difference calculating means 92 Cold water transport pump 94 Pressure sensor 96 Temperature sensor 98 Temperature sensor

Claims (16)

Supercooling control of the aqueous solution that generates ice slurry by supercooling the aqueous solution in the aqueous solution circuit by the latent heat of vaporization of the refrigerant in the refrigerator and releasing the supercooled aqueous solution downstream from the supercooling part of the aqueous solution circuit An aqueous solution that adjusts the evaporation temperature of the refrigerant so that the temperature difference between the aqueous solution freezing temperature downstream of the supercooling section and the evaporation temperature of the refrigerant becomes a constant value ΔT until the target degree of supercooling is achieved. In the subcooling control method,
When restarting the refrigerator,
Calculating the concentration of the aqueous solution based on the level of the aqueous solution in the aqueous solution tank that receives the ice slurry provided in the aqueous solution circuit, and predicting the freezing temperature of the aqueous solution based on the calculated aqueous solution concentration;
A step of initially setting the evaporation temperature of the refrigerant so that the temperature difference between the predicted freezing temperature of the aqueous solution and the evaporation temperature of the refrigerant becomes a constant value ΔT; Supercool the aqueous solution to prevent release,
After the supercooling of the aqueous solution in the aqueous solution circuit starts, the forced supercooling release operation is performed while the supercooling degree approaches the target supercooling degree until the supercooling release of the aqueous solution is achieved downstream from the supercooling section. Repeating the cycle of determining whether or not the supercooling release has been achieved,
By switching from the predicted freezing temperature of the aqueous solution to the measurement temperature of the ice slurry generated by the release of the supercooling, the temperature difference between the measurement temperature of the ice slurry and the evaporation temperature of the refrigerant becomes the constant value ΔT. Adjusting the evaporation temperature, and a method for controlling supercooling of an aqueous solution.   In the initial stage of evaporating temperature, the temperature difference between the temperature increased by a predetermined temperature relative to the predicted freezing temperature of the aqueous solution and the evaporating temperature of the refrigerant is constant so that the supercooling release of the supercooling portion of the aqueous solution circuit does not occur. The method for controlling supercooling of an aqueous solution according to claim 1, wherein the method is set so as to have a value ΔT. The supercooling release operation of the aqueous solution is performed by generating ice nuclei in the aqueous solution by the supercooling release unit provided downstream from the supercooling part of the aqueous solution circuit,
The step of repeating the supercooling release operation is performed after the temperature difference between the predicted freezing temperature of the aqueous solution and the aqueous solution temperature at the outlet of the supercooling releaser becomes a value sufficient to forcibly release the supercooling. The method for controlling supercooling of an aqueous solution according to claim 2. The aqueous solution according to claim 3, wherein the achievement of the supercooling cancellation of the aqueous solution is determined by a temperature difference between the aqueous solution temperature upstream of the supercooling releaser and the aqueous solution temperature downstream of the supercooling releaser becoming a predetermined temperature. Subcooling control method. The target supercooling degree of the aqueous solution is such that the supercooling is not canceled until the aqueous solution is supercooled in the supercooling part, and the supercooling is forcibly released downstream from the supercooling part after the supercooling of the aqueous solution starts. The method for controlling supercooling of an aqueous solution according to any one of claims 1 to 4, wherein the subcooling control method is set to a value sufficient for the above. The supercooling of the supercooled aqueous solution is canceled by an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
Repeating the step of operating and holding the ice nucleus generator until the temperature difference between the temperature of the aqueous solution upstream of the ice nucleus generator and the temperature of the aqueous solution downstream of the ice nucleus generator exceeds a predetermined value. Item 2. A method for controlling supercooling of an aqueous solution according to Item 1. The supercooling of the supercooled aqueous solution is canceled by an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
The temperature of the aqueous solution upstream of the ice nucleus generator decreases by a predetermined temperature until the temperature difference between the temperature of the aqueous solution upstream of the ice nucleus generator and the temperature of the aqueous solution downstream of the ice nucleus generator becomes a predetermined value or more. The method for controlling supercooling of an aqueous solution according to claim 1, wherein the step of operating the ice nucleus generator is repeated each time. The supercooling of the supercooled aqueous solution is canceled by an ice nucleus generator that transmits vibrations to the supercooled aqueous solution and generates ice nuclei in the aqueous solution.
After lowering the set initial evaporation temperature until the temperature difference between the aqueous solution temperature upstream of the ice nucleus generator and the aqueous solution temperature downstream of the ice nucleus generator exceeds a predetermined value, the ice nucleus is maintained. The method of controlling supercooling of an aqueous solution according to claim 1, wherein the step of operating the generator is repeated. A supercooling heat exchanger that supercools the aqueous solution by the latent heat of vaporization of refrigerant supplied from a compressor and a refrigerator that includes a condenser, a supercooling release unit that releases the supercooling state of the aqueous solution, and an aqueous solution tank that receives the aqueous solution In this order, an aqueous solution circuit connected via an aqueous solution pipe,
And a control circuit that adjusts the refrigerant evaporation temperature according to the freezing temperature of the aqueous solution.
A predictive calculator for predicting the freezing temperature of the aqueous solution based on the liquid level of the aqueous solution in the aqueous solution tank;
Evaporating temperature adjusting means for adjusting the evaporating temperature of the refrigerant so that a temperature difference between the aqueous solution temperature between the supercooling releaser and the aqueous solution tank and the evaporating temperature of the refrigerant becomes a constant value ΔT;
A switching means for switching between the predicted freezing temperature of the aqueous solution and the measured temperature of the ice slurry generated by releasing the supercooling for the aqueous solution temperature between the supercooling releaser and the aqueous solution tank,
Temperature difference calculating means for calculating a temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the supercooling releaser and the aqueous solution temperature between the supercooling releaser and the aqueous solution tank; ,
The evaporating temperature adjusting means determines that the temperature difference between the freezing temperature of the aqueous solution predicted by the predictive calculator and the evaporating temperature of the refrigerant is a constant value ΔT until the temperature difference calculated by the temperature difference calculating means reaches a predetermined value. As described above, the ice slurry generated by the supercooling release from the freezing temperature of the aqueous solution predicted by the switching unit when the evaporation temperature of the refrigerant is adjusted and the temperature difference calculated by the temperature difference calculating unit becomes a predetermined value. Switching to the measured temperature, and adjusting the evaporation temperature of the refrigerant so that the temperature difference between the measured temperature of the ice slurry generated by the supercooling release and the evaporation temperature of the refrigerant becomes a constant value ΔT.
A supercooling control device for an aqueous solution. The supercooling release device is an ice nucleus generator that transmits vibrations to the supercooled aqueous solution to generate ice nuclei in the aqueous solution.
Generation of ice nuclei until the temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the ice nucleus generator and the aqueous solution temperature between the ice nucleus generator and the aqueous solution tank reaches a predetermined value or more. The supercooling control device for an aqueous solution according to claim 9, wherein the step of operating and holding the vessel is repeated. The supercooling release device is an ice nucleus generator that transmits vibrations to the supercooled aqueous solution to generate ice nuclei in the aqueous solution.
Until the temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the ice nucleus generator and the aqueous solution temperature between the ice nucleus generator and the aqueous solution tank reaches a predetermined value or more, the ice nucleus The supercooling control device for an aqueous solution according to claim 9, wherein the step of operating the ice nucleus generator is repeated each time the temperature of the aqueous solution upstream of the generator decreases by a predetermined temperature. The supercooling release device is an ice nucleus generator that transmits vibrations to the supercooled aqueous solution to generate ice nuclei in the aqueous solution.
The temperature difference between the aqueous solution temperature between the supercooling heat exchanger and the ice nucleus generator and the aqueous solution temperature between the ice nucleus generator and the aqueous solution tank was set until a predetermined value or more was reached. The supercooling control device for an aqueous solution according to claim 9, wherein the step of operating the ice nucleus generator is repeated after lowering and maintaining the initial evaporation temperature. A cooling device comprising the supercooling control device for an aqueous solution according to any one of claims 9 to 12,
An ice slurry feed pipe that sends ice slurry generated by being overcooled by the supercool release unit to a load cooling side, and an aqueous solution return pipe that returns the aqueous solution from the load cooling side to the aqueous solution tank. And cooling device. A cooling system comprising the supercooling control device according to any one of claims 9 to 12,
The aqueous solution tank is an ice heat storage tank that receives the ice slurry generated by the supercool releaser and stores ice therein,
A load cooler is installed between the supercooling releaser and the ice heat storage tank,
A three-way switching valve between the supercooling releaser and the load cooler, and a load cooler bypass pipe connecting the three-way switching valve and the heat storage tank are provided,
By switching the three-way switching valve, the load cooler is cooled by ice slurry generated by the supercooling release by the supercooling releaser, or the supercooling release is performed via the load cooler bypass pipe A cooling system characterized in that it is possible to select whether to store ice in the heat storage tank by means of ice slurry generated by releasing supercooling by a vessel.   The temperature difference between the temperature of the ice slurry after the release of supercooling and the refrigerant evaporation temperature in the supercooling heat exchanger is controlled to maintain a constant value by controlling the evaporation pressure of the refrigerant in the supercooling heat exchanger. 15. A cooling system according to claim 14 characterized in that:   A control valve whose opening degree is adjusted based on a control signal from the control circuit is provided in the middle of the refrigerant return pipe between the refrigerant outlet of the supercooling heat exchanger and the suction port of the compressor. The cooling system according to claim 15, wherein the evaporating temperature of the refrigerant is adjusted by adjusting the opening degree.

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