JPH0810100B2 - Ice making equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ice making device in which water or an aqueous solution in an ice storage tank is circulated to be supercooled and then the supercooled state is eliminated to form a slurry-like ice product. Regarding operation control.

[0002]

2. Description of the Related Art Conventionally, this type of ice making device is provided with a water circulation path for circulating the water in the ice storage tank between the heat exchanger and the ice storage tank provided in the refrigerant circuit. The water in the ice storage tank is converted into slurry-like ice by heat exchange. Then, the place where the supercooled state is eliminated is to be performed after leaving the water circulation passage in order to avoid freezing of the water circulation passage. For example, in the technique disclosed in Japanese Patent Laid-Open No. 63-217171, the water circulation passage is arranged above the inclined upper ice storage tank near the outlet, and the supercooled state is eliminated at this inclined portion. It is intended to be dropped into the ice storage tank. Further, in the technique disclosed in Japanese Utility Model Laid-Open No. 1-112345, an inclined gutter having a baffle plate is installed in front of the outlet end of the water circulation path, and supercooled water is collided with the baffle plate to flow down the inclined gutter. It is made to drop in the ice storage tank.

[0003]

However, in the former one of the above techniques, it is necessary to provide the inclined portion with a considerable height difference, which is a great design constraint. In addition, there is a problem that the heat loss is large because it is exposed to the atmosphere for a long time.

On the other hand, in the latter one, since the supercooling elimination section is provided above the ice storage tank, if the distance between the heat exchanger and the subcooling elimination section is long, the supercooling state is eliminated by the pipe between them. In order to avoid such a situation, there is a problem that there are many design restrictions, such as that a heat exchanger must be installed near the ice storage tank.

Therefore, it is conceivable to try to make ice in the middle of the water circulation path and to send the ice inside the closed pipe to the ice storage tank while keeping it in a flowable slurry form.

However, if the difference between the temperature of the cooling surface of the supercooling elimination section and the temperature of the supercooled water is too large just by continuing the operation for eliminating the supercooled state, the ice particles will become coarse and the pipe An ice layer is formed on the wall to freeze the tube wall including the supercooling elimination part. Therefore, if the ice making efficiency is lowered and the ice accretion layer is further thickened, the pipeline may be blocked. Also, if the resolution is too small,
There may be an unexpected situation in which the elimination of the supercooled state does not occur at the supercooled elimination site but occurs in the downstream pipeline and blocks the pipeline.

The present invention has been made in view of the above problems, and an object thereof is to reliably eliminate a supercooled state at a supercooling eliminated portion in performing ice making operation, and to eliminate the supercooled state. The purpose of this is to prevent the ice formation caused by the excessive progress, thereby enabling highly reliable and highly efficient ice making operation.

[0008]

Means for Solving the Problems To achieve the above object, the means taken by the present invention is a subcooling to an optimum temperature at which the supercooled state is surely resolved and freezing of the pipeline does not occur. The cooling temperature of the elimination section is controlled, and the ice making operation control is performed in consideration of external factors that affect the control target value and control amount. Specifically, the first solution means of the present invention is, as shown in FIG. 1, connected to an ice storage tank (5) for storing a slurry-like frozen product of water or an aqueous solution, and a cooling device. The main heat exchanger (22) for supercooling the water or the aqueous solution and the main heat exchanger (2
A water circulation path (51) for forcedly circulating water or an aqueous solution between the ice storage tank (5) and the ice storage tank (5), and the heat exchanger (22).
Provided in the water circulation path (51) on the downstream side, the main heat exchanger (2
It is premised on an ice making device provided with a variable capacity subcooling elimination unit (8) that eliminates the supercooled state by cooling the water or aqueous solution supercooled in 2) to generate slurry-like ice. To do.

Further, a cooling surface temperature detecting means (A) for detecting the cooling surface temperature of the subcooling elimination portion (8) and a cooling surface temperature signal from the cooling surface temperature detecting means (A) are received, and the cooling surface is received. A structure is provided in which a temperature is compared with a predetermined target elimination temperature, and cooling surface temperature control means (B1) is provided to control the elimination capacity of the subcooling elimination unit (8) so that the cooling surface temperature reaches the target elimination temperature. Is.

A second solving means is, in addition to the ice making device, a cooling surface temperature detecting means (A) for detecting a cooling surface temperature of the supercooling eliminating portion (8) and the supercooling eliminating portion (8). A flow velocity detecting means (C) for detecting the flow velocity of the flow at the installation location, and an optimum value setting means for receiving a flow velocity signal from the flow velocity detecting means (C) and setting a target elimination temperature suitable for the current flow velocity ( D), a cooling surface temperature signal from the cooling surface temperature detecting means (A), the optimum value setting means (D), and a cooling surface temperature signal from the cooling surface temperature detecting means (A),
A cooling surface that receives the target elimination temperature signal from the optimum value setting means (D), compares the two temperatures, and controls the elimination capacity of the subcooling elimination portion (8) so that the cooling surface temperature becomes the target elimination temperature. The temperature control means (B2) is provided.

A third solving means is, in addition to the ice making device, a cooling surface temperature detecting means (A) for detecting a cooling surface temperature of the supercooling eliminating portion (8), and the cooling surface temperature detecting means (A). ), The cooling surface temperature is compared with a predetermined target elimination temperature, and the elimination capacity of the subcooling elimination unit (8) is controlled so that the cooling surface temperature becomes the target elimination temperature. Ice formation detecting means (E) for detecting ice formation by the cooling surface temperature control means (B1) and the supercooling elimination portion (8).
And a cooling capacity reduction means (F) for receiving the ice generation signal from the ice generation detection means (E) and lowering the elimination capacity of the supercooling elimination part (8).

A fourth solving means is, in addition to the ice making device, a cooling surface temperature detecting means (A) for detecting a cooling surface temperature of the supercooling eliminating portion (8), and the supercooling eliminating portion (8). Flow velocity detecting means (C) for detecting the flow velocity of the flow at the installation location, and optimum value setting means (D) for receiving the flow velocity signal from the flow velocity detecting means and setting a target elimination temperature suitable for the current flow velocity. , The cooling surface temperature signal from the cooling surface temperature detecting means (A) and the optimum value signal from the optimum value setting means (D) are received, and both temperatures are compared so that the cooling surface temperature becomes the target elimination temperature. Cooling surface temperature control means (B2) for controlling the elimination capacity of the supercooling elimination part (8), ice production detection means (E) for detecting the production of ice by the subcooling elimination part (8), and the ice production Receiving the ice generation signal from the detection means (E), the supercooling elimination section (8) eliminates Is obtained by a configuration in which the cooling capacity reduction means for reducing the force (F).

[0013]

With the above structure, water or an aqueous solution is circulated between the ice storage tank (5) and the main heat exchanger (22), and the supercooling elimination section (8) is provided in the middle of the water circulation path (51). The supercooled state is eliminated and slurry ice is generated. In this ice making operation, according to the first aspect of the invention, when the cooling surface temperature detecting means (A) detects a signal of the cooling surface temperature of the supercooling eliminating portion (8), the cooling surface temperature control means (B1). The cooling surface temperature is compared with the target elimination temperature, the deviation is corrected, and the elimination capacity of the subcooling elimination unit (8) is controlled so as to reach the target elimination temperature. Therefore, the cooling surface temperature of the supercooling elimination section (8) is always controlled to the target elimination temperature set as the optimum elimination temperature in advance.

According to the second aspect of the present invention, in the ice making operation, the flow velocity detecting means (C) detects the flow velocity, and based on the flow velocity signal, the optimum value setting means (D) sets a target suitable for the current flow velocity. Set the elimination temperature. Then, the cooling surface temperature control means (B2) compares the cooling surface temperature detected by the cooling surface temperature detecting means (A) with the target elimination temperature set by the optimum value setting means (D) to obtain the cooling surface temperature. The elimination capacity of the supercooling elimination section (8) is controlled so that the temperature becomes the target elimination temperature. Therefore, even if the target elimination temperature fluctuates due to an increase or decrease in the flow velocity at the location where the supercooling elimination unit (8) is provided, the supercooling elimination unit ( The solution ability of 8) is controlled.

Further, in the above ice making operation, when the freezing is started, a large amount of cold heat, which has been used as a temperature shock for eliminating the supercooled state until then, is used for cooling the supercooling elimination section (8). It begins to be broken. Further, when the ice attached to the cooling surface of the supercooling elimination section (8) grows, the ice blocks heat exchange between the supercooling elimination section (8) and the fluid, so that the subcooling elimination section (8) is cooled. Become so. Due to these phenomena, after the ice is generated, the cooling surface temperature Tc of the supercooling elimination section (8) tends to decrease as shown in FIG. for that reason,
Inconveniences occur such that the ice is difficult to peel off from the supercooling elimination section (8) or the ice particles become too large, thereby blocking the pipeline. Therefore, in the invention of claim 3, in addition to the invention of claim 1 described above, an ice formation detecting means (E) and an elimination capability reducing means (F) are provided. Then, the ice generation detecting means (E) detects the generation of ice by the supercooling elimination section (8). Based on this ice generation signal, the elimination capacity reducing means (F) reduces the elimination capacity of the supercooling elimination section (8), so that the adverse effect of ice production is canceled.

According to the invention of claim 4, the flow velocity detecting means (C).
And the optimum value setting means (D) set the optimum value corresponding to the flow velocity, and when ice is generated, the ice generation detecting means (E) and the elimination capability means (F) determine the cooling surface temperature. Since the downward tendency is canceled out, the ice making operation control corresponding to the change of the flow velocity and the change of the phase state of the fluid is performed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows the construction of the refrigerant circuit (1) of the air conditioner of one embodiment according to the present invention. In the figure, (11) is a first compressor, (12) is arranged on the discharge side of the first compressor (11), and an outdoor heat exchanger for exchanging heat between refrigerant and outdoor air, and (13) is An outdoor electric expansion valve that adjusts the refrigerant flow rate of the outdoor heat exchanger (12) or decompresses it, wherein the devices (11) to (13) are connected in series in a first conduit (14). Has been done.

Further, (21) is a second compressor, and (22) is arranged on the discharge side of the second compressor (21) to supercool water or an aqueous solution in an ice storage tank (5) described later. The water heat exchanger, which is the main heat exchanger of (23), regulates the refrigerant flow rate when the water heat exchanger (22) functions as a condenser, and depressurizes the refrigerant when the water heat exchanger (22) functions as an evaporator. In the electric expansion valve, the devices (21) to (23) are connected in series in the second pipe line (24).

Note that (SD1) and (SD2) are oil separators provided in the discharge pipes of the compressors (11) and (21), respectively, and (C1) and (C2) are the oil separators (SD1). ),
(SD2) is a pressure reducing capillary tube provided in oil return pipes (RT1), (RT2) respectively provided on the suction sides of the compressors (11), (21).

Further, (32) and (32) are indoor heat exchangers arranged in each room, and (33) and (33) are indoor electric expansion valves as pressure reducing valves for reducing the pressure of the refrigerant. The devices (32) and (33) are connected in series, and the respective sets are connected in parallel in the third conduit (34).

The first conduit (14) and the second conduit (24) are connected in parallel with the third conduit (34). In addition, (Ac) is each compressor (11), (21)
Is an accumulator provided in the third pipe line (34) on the suction side of.

Further, (2) shows the gas pipe of the outdoor heat exchanger (12) and the gas pipes of the indoor heat exchangers (32), (32) on the discharge side of the compressors (11), (21) or A four-way switching valve (2) that is switched so as to communicate alternately with the suction side. When the four-way switching valve (2) is switched to the solid line side in the figure, the outdoor heat exchanger (12) is a condenser, an indoor unit. Heat exchanger (32),
While (32) functions as an evaporator and performs the cooling operation indoors, when the four-way switching valve (2) is switched to the broken line side in the figure, the outdoor heat exchanger (12) is an evaporator and an indoor heat exchanger. (3
2) and (32) function as a condenser to perform heating operation in the room.

Further, the branch passage (25) for bypass-connecting the gas pipe of the water heat exchanger (22) and the suction pipes of the compressors (11) and (21) and the water heat exchanger (22). A water side switching valve (26) for alternately connecting the gas pipe to the discharge pipe of the second compressor (21) and the branch passage (25) is provided. The water side switching valve (26) utilizes three ports of the four-way switching valve, and when the water side switching valve (26) is switched to the solid line side in the figure, the water heat exchanger (22 ) Is connected to the branch passage (25) side, that is, the suction side of each compressor (11), (21), and the water heat exchanger (22) functions as an evaporator, while the water side switching valve (26 ) Is switched to the broken line side in the figure, the gas pipe of the water heat exchanger (22) communicates with the discharge pipe of the second compressor (21) so that the water heat exchanger (22) functions as a condenser. Has been done. In addition, (C3)
Is a capillary tube provided in the dead port side pipe of the water side switching valve (26).

Further, a bypass passage (3) for connecting the discharge pipes of the first compressor (11) and the second compressor (21) is provided, and the second compressor is provided in the bypass passage (3). A check valve (4) that allows only the refrigerant to flow from the discharge pipe side of (21) to the discharge pipe side of the first compressor (11) is interposed.

That is, when the outdoor heat exchanger (12) and the water heat exchanger (22) function as condensers, if the condensation temperature in the water heat exchanger (22) is high and the pressure is high, the second compression is performed. The gas discharged from the machine (21) is used as an outdoor heat exchanger (1
The amount of heat radiation can be distributed by letting it escape to the 2) side.

Here, the air conditioner is provided with an ice storage tank (5) for storing a slurry-like iced product of water or an aqueous solution as a heat storage medium, and the ice storage tank (5). The water and the water heat exchanger (22) are connected by a water circulation path (51) so that water or an aqueous solution can circulate. The water circulation path (51) extends from the bottom of the ice storage tank (5) to the water heat exchanger (2).
Outgoing line (51A) for supplying water etc. to 2) and returning line (51B) for returning slurry-like iced matter such as water from the water heat exchanger (22) to the upper part of the ice storage tank (5) And a pump (52) provided in the forward passage (51A) forcibly circulates the water or the aqueous solution in the ice storage tank (5) in the water circulation passage (51).

Then, the forward path (51) of the water circulation path (51)
A water circulation path (51) is provided downstream of the pump (52) of A).
A strainer (53) for removing solid matters such as iced matter and dust in the water or aqueous solution of the above is interposed, and further, a water heat exchanger (22) is provided on the downstream side of the strainer (53). A preheat heat exchanger (6) for preheating water or the like supplied to the is installed. On the other hand, the liquid line of the refrigerant circuit (1) is provided with a preheating bypass passage (61) for allowing a part of the liquid refrigerant to bypass the water side electric expansion valve (23) and flow to the preheating heat exchanger (6). A preheat electric expansion valve (62) having a refrigerant decompression function and a flow rate control function is provided downstream of the preheat heat exchanger (6) in the preheat bypass passage (61). The preheat electric expansion valve (62) and the water side electric expansion valve (23) adjust the refrigerant flow rate in the preheat bypass passage (61) and reduce the pressure of the refrigerant during the ice making operation of the water heat exchanger (22). Is also supposed to do.

Further, in the return pipe (51B) of the water circulation passage (51), the water or the like in the return pipe (51B) is cooled on the downstream side of the water heat exchanger (22) to cool the water heat exchanger. (2
A recooler (8) is provided as a supercooling elimination unit for eliminating a supercooled state of water or the like supercooled in 2), and further,
Between the recooler (8) and the water heat exchanger (22), a freezing progress prevention unit for preventing freezing of the return conduit (51B) from proceeding to the water heat exchanger (22). A heat insulation heat exchanger (7) is provided. Further, a heat retaining passage (36) for allowing the liquid refrigerant to flow is provided in the heat retaining heat exchanger (7) from the liquid line of the refrigerant circuit (1). Further, a recooling bypass passage (37) branches from the liquid line on the downstream side of the heat retaining passage (36) during the ice making operation of the water heat exchanger (22). The recooling bypass passage (3
7) The compressor (11), (2) is passed through the recooler (8).
An electric expansion valve (72) having a refrigerant decompression function and a flow rate control function is provided on the upstream side of the recooler (8) while being connected to the branch passage (25) on the suction side of 1). Has been done.

That is, in the recooler (8), the water and the like supercooled in the water heat exchanger (22) are recooled by heat exchange with the refrigerant whose pressure is reduced by the electric expansion valve (72), and The supercooled state is eliminated and the slurry is iced, and the slurry-like iced matter is stored in the ice storage tank (5) via the return pipe (51B).
Circulate up to. Further, by heating from the outer circumference of the pipe in the heat retention heat exchanger (7), it is possible to prevent the freezing of the pipe wall caused by icing from reaching the water heat exchanger (22).

When the air-conditioning operation is performed indoors during operation of this air conditioner, the four-way switching valve (2) is switched to the solid line side in the figure. When the water side switching valve (26) is switched to the solid line side in the figure, each compressor (1
After the discharge refrigerants from 1) and (21) are both condensed in the outdoor heat exchanger (12), the indoor heat exchangers (32),
The room is cooled by evaporating in (32). Further, when the water side switching valve (26) is switched to the broken line side in the figure, the refrigerant discharged from the first compressor (11) flows to the outdoor heat exchanger (12), while the second compressor (21). The discharged refrigerant of (1) flows into the water heat exchanger (22), is condensed, and then circulates so as to be evaporated in the indoor heat exchangers (32) and (32).

When the electric power is cheap at night or the like, the cold storage operation for storing the cold heat in the ice storage tank (5) is performed. That is, the four-way switching valve (2) and the water side switching valve (26) are switched to the solid line side in the figure, and the indoor electric expansion valves (33), (33) are switched.
Closed and the refrigerant discharged from the compressors (11) and (21) is condensed in the outdoor heat exchanger (12).
3) (or preheat electric expansion valve (62)) to reduce the pressure and evaporate in the water heat exchanger (22). This allows the ice storage tank (5)
Supercool the water or aqueous solution of. Then, the supercooled water or the like is recooled by the recooler (supercooling elimination section) (8), the supercooled state is eliminated, and it is frozen into slurry. And
This iced product is forcibly circulated and stored in the ice storage tank (5) while being kept in the form of a fluid slurry, and is used as cold heat during the daytime cooling operation.

On the other hand, as a feature of the present invention, as shown in FIG. 3, the recooler (8) includes a cooling surface temperature Tc of the recooler.
A recooler sensor (81) for detecting is provided.
In the return conduit (51B), a flow velocity detection sensor (82) that detects the flow velocity u of the flow of water or aqueous solution at the location where the recooler (8) is installed, and the downstream side of the recooler (8). A fluid temperature sensor (70) for detecting the fluid temperature Tw is arranged at the position.

The detection signals of the cooling surface temperature Tc, the fluid temperature Tw, and the flow velocity u are input to the controller (10), and the controller (10) controls the operation of the supercooling elimination section (8).

The control contents of this ice making operation will be described with reference to the flowchart of FIG.

First, in step S1, the cooling surface temperature Tc detected by the recooler sensor (81), the flow velocity u detected by the flow velocity detection sensor (82), and the fluid temperature sensor (70) are detected. Read the fluid temperature Tw. After that, the process proceeds to step S2, and the critical elimination temperature TRc corresponding to the current flow velocity u, which is the target elimination temperature, is
The calculation is performed based on the TRc line (FIG. 6) described later. at the same time,
The temperature difference ΔTw and the temperature gradient τ (ΔTw / Δt) are calculated based on the current fluid temperature Tw value and the previous fluid temperature Twp value.

Then, the process proceeds to step S3, and the ice formation condition is judged, that is, the surface temperature Tw is a predetermined value Ah 1 (for example, a value of about 0.5 ° C.) from the freezing point Tg (0 ° C.) of the fluid. It is determined whether or not the value is equal to or more than the value (Tg-Ah 1) after subtracting. Then, if Tw ≧ (Tg−Ah 1), it is determined that ice is generated, and the process proceeds to step S4.

On the other hand, when the determination in step S3 is NO, the process proceeds to step S5, and it is determined whether or not the temperature gradient τ is equal to or more than a predetermined set value Ah 2. When τ ≧ Ah2,
The determination is YES, and even if the fluid temperature Tw is lower than the freezing point Tg, it is determined that ice is generated and the process proceeds to step S4.

In step S4, it is determined whether the cooling surface temperature Tc is lower than the freezing point Tg. If Tc <Tg, the process proceeds to step S6, and it is determined whether the cooling surface temperature Tc is higher than the criticality elimination temperature TRc. If Tc> TRc, the opening Ev of the electric expansion valve is left unchanged, that is, the cooling surface temperature Tc is kept at that temperature in step S.
Return to 1. On the other hand, if the cooling surface temperature Tc is not higher than the criticality elimination temperature TRc, the process proceeds to step S7. In step S7, the opening Ev of the electric expansion valve (72) is set to a temperature difference (TRc−) at which the current cooling surface temperature Tc deviates from the criticality elimination temperature TRc.
Increase by Tc). K2 is a constant for changing the temperature difference into the opening.

Next, the process proceeds to step S8, the detected temperature Tw of this time is set to the detected temperature Twp of the previous time, and step S8 is executed.
9, the timer starts counting, and then it proceeds to step S10 to determine whether or not the count has reached a predetermined sampling time. When the sampling time has not been reached, the counting is continued, while when the counting reaches the sampling time, the process returns to step S1.

In step S4, if the cooling surface temperature Tc is higher than the freezing point Tg, the process proceeds to step S11, and the opening Ev of the electric expansion valve (72) is set so that the current cooling surface temperature Tc is higher than the freezing point Tg. Temperature difference (Tg-Tc)
And decrease the cooling surface temperature Tc. K1 is a constant for changing the temperature difference into the opening. After this, step S
8, the detected temperature Tw of this time is set to the detected temperature Twp of the previous time, the sampling time is counted in steps S9 and S10, and then the process returns to step S1.

In step S5, the temperature gradient τ
Is lower than the set value Ah 2, it is determined that ice is not generated, and the process proceeds to step S12 to determine whether the cooling surface temperature Tc is lower than the criticality elimination temperature TRc. When Tc <TRc, the opening Ev of the electric expansion valve (72) is left unchanged, that is, the cooling surface temperature Tc is kept at that temperature, and the process returns to step S1. On the other hand, if the current cooling surface temperature Tc is equal to or higher than the criticality elimination temperature TRc, the process proceeds to step S13. In step S13, the opening Ev of the electric expansion valve (72) is reduced by the temperature difference (Tc-TRc) in which the cooling surface temperature Tc deviates from the criticality elimination temperature TRc, and the cooling surface temperature Tc is lowered. K3 is a constant for changing the temperature difference into the opening.
Then, the process proceeds to step S8, the detected temperature Tw of this time is set to the previously detected temperature Twp, and further, step S9,
After counting the sampling time in S10,
Return to step S1.

In the above ice making operation, the fluid temperature Tw and its temperature gradient τ were used as the ice production conditions. Regarding the fluid temperature Tw, as shown in FIG. 5, the fluid temperature Tw is lower than the freezing point Tg in the supercooled state, but rises to the freezing point (0 ° C.) when the supercooled state is eliminated. Therefore, the formation of ice can be detected by measuring whether the fluid temperature Tw reaches the freezing point Tg. With respect to the temperature gradient τ, the fluid temperature Tw rises sharply as the icing progresses rapidly. Therefore, it is possible to detect the production of ice by measuring the change in the gradient of the temperature gradient τ.

In the control flow of the above embodiment, the cooling surface temperature control means (B1) according to the invention of claim 1 is constituted by steps S12 and S13.

Then, the recooler sensor (81) as the cooling surface temperature detecting means (A) detects the cooling surface temperature Tc, and when the cooling surface temperature control means (B1) receives the cooling surface temperature signal, Compare the cooling surface temperature with the target elimination temperature.

The target elimination temperature is set to the critical elimination temperature TRc1 corresponding to a predetermined flow velocity u1 as shown in FIG. The criticality elimination temperature TRc1 is a temperature at which elimination of the supercooled state easily starts. This criticality elimination temperature TRc
The supercooled state is stable at a temperature between the freezing point and the freezing point Tg, and it is difficult to freeze. On the other hand, since the supercooled state is unstable in a temperature range lower than the criticality elimination temperature TRc, water or an aqueous solution tends to eliminate this state and become ice. Therefore, the criticality elimination temperature TRc is set to the target elimination temperature. The reason why the temperature lower than the criticality elimination temperature TRc was not set as the target elimination temperature is that the lower the cooling surface temperature Tc, the more easily ice accretion occurs in the recooler (8), and the ice making efficiency decreases if the pipe wall freezes. This is because if the ice accretion layer becomes thicker, the re-cooler (8) will be clogged, and if the ice accretion is peeled off and flows downstream, there will be a problem such as clogging in the downstream pipeline.

Next, the control signal corresponding to the temperature difference between the criticality elimination temperature TRc and the cooling surface temperature Tc is given to the controller (1
0) to the electric expansion valve (72). Electric expansion valve (7
2) changes the refrigerant flow rate so that the cooling surface temperature Tc of the recooler (8) is the target elimination temperature, that is, the critical elimination temperature TRc.
Adjusted to be 1.

Therefore, the cooling surface temperature Tc is controlled to the optimum elimination temperature of the supercooled state, and it is possible to surely eliminate the supercooled state and prevent the freezing of the pipeline.

Next, in the control flow of the above embodiment,
The target value setting means (D) in the invention of claim 2 is constituted by steps S1 and S2.

The elimination capability control means (B2) is operated in step S
12, S13.

In the invention of claim 2, the flow velocity detecting means (C).
The flow velocity u is detected by the flow velocity detection sensor (82), and the optimum value setting means (D) detects the flow velocity u based on the flow velocity signal.
The target elimination temperature is set.

The target elimination temperature is set to the critical elimination temperature TRc as in the first aspect. However, the criticality elimination temperature TRc
Rises in proportion to the flow velocity, and the TRc line is drawn as shown in FIG. In the region surrounded by the TRc line and the isothermal line of the freezing point Tg, the supercooled state is stable (supercooled stable region), and it is difficult to freeze. On the other hand, since the supercooled state is unstable in a temperature region relatively lower than the freezing point Tg (supercooled unstable region), water or an aqueous solution is likely to dissolve in the supercooled state and become iced. Therefore, in the present invention, the target elimination temperature is changed according to the flow velocity so that the control along the TRc line can be performed. The reason why the instability of supercooling, which is lower than the criticality elimination temperature TRc, was not set as the target elimination temperature,
As described in the first aspect of the invention, as the cooling surface temperature Tc becomes lower, icing is more likely to occur in the recooler (8), the ice making efficiency is reduced due to freezing of the pipe wall, and the pipe line is blocked. This is because such adverse effects as described above occur.

Then, the cooling surface temperature control means (B2)
Thus, the cooling surface temperature Tc is compared with the target elimination temperature, that is, the critical elimination temperature TRc, a control signal corresponding to the deviation is sent to the electric expansion valve (72), and the cooling surface temperature Tc becomes the critical elimination temperature TRc. Thus, the elimination capacity of the supercooling elimination section (8) is controlled.

Specifically, in the control flow of FIG.
In the subcooling stable region where the cooling surface temperature Tc is higher than the criticality elimination temperature TRc in step S12, the electric expansion valve (72)
The opening Ev of is reduced to lower the cooling surface temperature Tc. On the other hand, in the supercooling unstable region where the cooling surface temperature Tc is lower than the critical temperature elimination temperature TRc, the process returns from step S13 to step S1, the opening Ev of the electric expansion valve (72) is maintained as it is, and the cooling surface temperature Tc is set to the current value. Keep at temperature. That is, when the cooling surface temperature Tc is in the supercooling stable region where the temperature is higher than the TRc line as in the main control operation before ice formation, it is necessary to perform cooling in order to eliminate the supercooling state. Further, in this case, since the cold heat is used as a temperature shock for eliminating the supercooling state, even if the cooling surface temperature Tc is in the stable subcooling region lower than the TRc line, the cooling surface temperature Tc is the TRc line. It is located near the TRc line without any further decrease. Therefore, there is no problem even if the cooling surface temperature Tc is not lowered.

Therefore, the critical elimination temperature TRc is increased or decreased by increasing or decreasing the flow velocity at the location where the supercooling elimination portion (8) is arranged.
Even when fluctuates, the target elimination temperature can be set to the critical elimination temperature TRc most suitable for the current flow velocity.

Next, in the above control flow, claim 3
The ice formation detecting means (E) in the invention of claim 1 is step S1.
~ S5.

The elimination capability reducing means (F) is operated in step S
4, S6, S7.

According to the invention of claim 3, in addition to the cooling surface temperature detecting means (A) and the cooling surface temperature controlling means (B1) of the invention of claim 1, the fluid temperature which is the ice formation detecting means (E) Generation of ice is detected by the sensor (70), and based on this ice generation signal, the cooling capacity reducing means (F) reduces the cooling capacity of the cooling surface temperature control means (B1).

Specifically, in the control flow of FIG.
In the supercooling unstable region where the cooling surface temperature Tc is lower than the freezing point Tg in step S4 and the cooling surface temperature Tc is lower than the criticality elimination temperature TRc in step S6, the opening Ev of the electric expansion valve (72) is increased to increase the cooling surface. Increase temperature Tc. On the other hand, in the supercooling unstable region where the cooling surface temperature Tc is higher than the criticality elimination temperature TRc, from step S6 to step S6.
Returning to 1, the cooling surface temperature Tc is maintained at the present temperature.

That is, when the icing is started, the large amount of cold heat, which has been used as a temperature shock for eliminating the supercooled state until then, begins to be used for cooling the supercooling elimination section (8). After that, when the ice attached to the cooling surface of the supercooling elimination unit (8) grows, the ice blocks heat exchange between the supercooling elimination unit (8) and the fluid, so that the subcooling elimination unit (8) is cooled. Become so. Due to these phenomena, after the ice is generated, the cooling surface temperature Tc of the supercooling elimination section (8) tends to decrease as shown in FIG.

Therefore, in order to cancel such a downward tendency of the cooling surface temperature Tc, the cooling surface temperature Tc is increased in the supercooling unstable region lower than the TRc line. On the other hand, when the cooling surface temperature Tc is higher than the TRc line in the stable supercooling region, the current cooling surface temperature Tc can be sufficiently lowered to the TRc line, so that temperature should be maintained. .

Therefore, according to the present invention, it is possible to cancel the adverse effect of ice formation. That is, according to the present invention, by detecting a disturbance such as ice formation, before the adverse effect that the cooling surface temperature Tc deviates from the TRc line appears, the effect is canceled out, so to speak, feedforward control is performed. Is.

By the way, when ice is generated, the cooling surface temperature Tc
In addition to feedforward control, as a control to correct the adverse effect of ice formation that the
Feedback control of the cooling surface temperature Tc can be considered. However, in the feedback control, after the cooling surface temperature Tc becomes much lower than the criticality elimination temperature TRc due to the formation of ice, the cooling surface temperature Tc is reduced to the criticality elimination temperature TRc.
The control correction tends to be slow because it is intended to restore the control. Therefore, the cooling surface temperature Tc may not reach the criticality elimination temperature TRc, and a constant error may occur. On the other hand, in the feedforward control according to the present invention, the control is corrected before the adverse effect of ice formation appears on the cooling surface temperature Tc, so that the cooling surface temperature Tc can be made equal to the target elimination temperature, and the accuracy can be improved. Good control is possible.

Next, according to the invention of claim 4, the target elimination temperature can be set to the critical elimination temperature TRc corresponding to the flow velocity by the flow velocity detecting means (C) and the optimum value setting means (D). When ice is generated, the decreasing tendency of the cooling surface temperature can be canceled by the ice generation detecting means (E) and the elimination capability means (F). Therefore, the ice making operation control corresponding to the change of the flow velocity and the change of the state of the fluid can be performed, and the control with higher accuracy can be performed.

[0065]

As described above, according to the first aspect of the present invention, water or an aqueous solution in the ice storage tank is circulated to be supercooled, and then the supercooled state is eliminated to form a slurry-like iced product. In the ice making device, when the cooling surface temperature control means (B1) receives the cooling surface temperature signal from the cooling surface temperature detecting means (A), the cooling surface temperature signal is compared with the target elimination temperature,
The elimination capacity of the supercooling elimination section (8) is controlled so that the cooling surface temperature becomes the target elimination temperature. Therefore, the cooling surface temperature Tc can be controlled to the target elimination temperature, that is, the optimal elimination temperature of the supercooled state, the supercooled state can be surely eliminated, and the freezing of the pipeline can be prevented.

According to the second aspect of the invention, the flow velocity detecting means (C) detects the flow velocity, and based on the flow velocity signal, the optimum value setting means (D) adjusts the target elimination temperature to the optimum value corresponding to the fluctuation of the flow velocity. Since the cooling surface temperature control means (B2) controls the cooling surface temperature so that the optimum cooling value is set to the optimum value, the cooling capacity is controlled by the cooling surface temperature control means (B2). In this case, it is possible to quickly respond to an error from the designed flow velocity and a change in the flow velocity during the ice making operation, so that the cooling surface temperature can always be kept at the optimum value.

According to the third aspect of the invention, the generation of ice is detected by the ice generation detecting means (E), and based on this ice generation signal, the cooling capacity reducing means (F) causes the supercooling elimination section (8). ) Is configured to reduce the cooling capacity, it is possible to cancel the adverse effect of ice formation. Further, since the feedforward control is performed based on the generation of ice, it is possible to perform accurate control.

According to the invention of claim 4, the target elimination temperature can be set to the critical elimination temperature TRc corresponding to the flow velocity, and when ice is generated, the decreasing tendency of the cooling surface temperature can be canceled. The ice making operation control corresponding to the change of the flow velocity and the change of the fluid state can be performed, and the control with higher accuracy can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the invention.

FIG. 2 is a refrigerant piping system diagram showing a configuration of an air conditioner.

FIG. 3 is a vertical cross-sectional view showing the arrangement of various sensors in the circulation path.

FIG. 4 is a flowchart showing ice making operation control.

FIG. 5 is a characteristic diagram showing changes over time in the fluid temperature and the cooling surface temperature of the recooler at the time of ice formation.

FIG. 6 is a vertical cross-sectional view showing the state of ice when ice is generated.

[Explanation of symbols]

 1 Refrigerant circuit 5 Ice storage tank 8 Recooler (supercooling elimination part) 9 Heater (freezing prevention part) 10 Controller 22 Water heat exchanger (main heat exchanger) 51 Water circulation path A Cooling surface temperature detection means B Cooling surface Temperature control means C Flow velocity detection means D Optimal value setting means E Ice formation detection means F Elimination capability reduction means

Claims (4)

[Claims] 1. A main heat exchanger (22), which is connected to an ice storage tank (5) for storing a slurry of iced water or an aqueous solution and a cooling device for supercooling the water or the aqueous solution. When,
A water circulation path (51) for forcibly circulating water or an aqueous solution between the main heat exchanger (22) and the ice storage tank (5);
It is provided in the water circulation path (51) on the downstream side of the heat exchanger (22), and the supercooled state is eliminated by cooling the water or the aqueous solution supercooled by the main heat exchanger (22) to form a slurry form. An ice making device including a variable capacity supercooling elimination section (8) for producing ice, comprising cooling surface temperature detection means (A) for detecting a cooling surface temperature of the supercooling elimination section (8), When receiving the cooling surface temperature signal from the cooling surface temperature detecting means (A), the cooling surface temperature is compared with a predetermined target elimination temperature, and the supercooling elimination portion (8) is adjusted so that the cooling surface temperature becomes the target elimination temperature. And a cooling surface temperature control means (B1) for controlling the elimination ability of the ice making device. 2. A main heat exchanger (22) connected to an ice storage tank (5) for storing a slurry of iced water or an aqueous solution and a cooling device for supercooling the water or the aqueous solution. When,
A water circulation path (51) for forcibly circulating water or an aqueous solution between the main heat exchanger (22) and the ice storage tank (5);
It is provided in the water circulation path (51) on the downstream side of the heat exchanger (22), and the supercooled state is eliminated by cooling the water or the aqueous solution supercooled by the main heat exchanger (22) to form a slurry form. An ice making device comprising a variable capacity supercooling eliminating section (8) for producing ice, comprising: a cooling surface temperature detecting means (A) for detecting a cooling surface temperature of the supercooling eliminating section (8); The target elimination temperature suitable for the current flow velocity is received by receiving the flow velocity detection means (C) for detecting the flow velocity of the flow at the location where the supercooling elimination portion (8) is provided and the flow velocity signal from the flow velocity detection means (C). The optimum value setting means (D) for setting the temperature, the cooling surface temperature signal from the cooling surface temperature detecting means (A), and the target elimination temperature signal from the optimum value setting means (D) are received. By comparison, the supercooling elimination section (8) is eliminated so that the cooling surface temperature reaches the target elimination temperature. An ice making device comprising: a cooling surface temperature control means (B2) for controlling the capacity. 3. A main heat exchanger (22) connected to an ice storage tank (5) for storing a slurry of iced water or an aqueous solution and a cooling device for supercooling the water or the aqueous solution. When,
A water circulation path (51) for forcibly circulating water or an aqueous solution between the main heat exchanger (22) and the ice storage tank (5);
It is provided in the water circulation path (51) on the downstream side of the heat exchanger (22), and the supercooled state is eliminated by cooling the water or the aqueous solution supercooled by the main heat exchanger (22) to form a slurry form. An ice making device comprising a variable capacity supercooling eliminating section (8) for producing ice, comprising: a cooling surface temperature detecting means (A) for detecting a cooling surface temperature of the supercooling eliminating section (8); Upon receiving the cooling surface temperature signal from the cooling surface temperature detecting means (A), the cooling surface temperature is compared with a predetermined target elimination temperature, and the supercooling elimination portion (8) is set so that the cooling surface temperature becomes the target elimination temperature. )
Cooling surface temperature control means (B1) for controlling the elimination capacity of
When receiving the ice production detecting means (E) for detecting the production of ice by the supercooling eliminating portion (8) and the ice production signal from the ice producing detecting means (E), the supercooling eliminating portion (8) An ice-making device comprising: a cooling capacity reducing means (F) for reducing the elimination capacity. 4. A main heat exchanger (22) connected to an ice storage tank (5) for storing a slurry of iced water or an aqueous solution and a cooling device for supercooling the water or the aqueous solution. When,
A water circulation path (51) for forcibly circulating water or an aqueous solution between the main heat exchanger (22) and the ice storage tank (5);
It is provided in the water circulation path (51) on the downstream side of the heat exchanger (22), and the supercooled state is eliminated by cooling the water or the aqueous solution supercooled by the main heat exchanger (22) to form a slurry form. An ice making device comprising a variable capacity supercooling eliminating section (8) for producing ice, comprising: a cooling surface temperature detecting means (A) for detecting a cooling surface temperature of the supercooling eliminating section (8); A flow velocity detection means (C) for detecting the flow velocity of the flow at the location where the supercooling elimination portion (8) is provided, and a flow velocity signal from the flow velocity detection means are received to set a target elimination temperature suitable for the current flow velocity. Optimal value setting means (D), cooling surface temperature signal from cooling surface temperature detecting means (A), and optimum value setting means (D)
And a cooling surface temperature control means (B2) for controlling the elimination capacity of the supercooling elimination portion (8) so that the cooling surface temperature reaches the target elimination temperature. In response to the ice formation detecting means (E) for detecting the generation of ice by the supercooling eliminating portion (8) and the ice formation signal from the ice formation detecting means (E), the supercooling eliminating portion (8) eliminates the ice. An ice making device comprising: a cooling capacity reducing means (F) for reducing the capacity.