WO2020136997A1

WO2020136997A1 - Operation control method for ice maker

Info

Publication number: WO2020136997A1
Application number: PCT/JP2019/033661
Authority: WO
Inventors: 宏一北; 明裕梶本; 一彦西原; 孝将伊東; 裕司山中; 植野　武夫
Original assignee: ダイキン工業株式会社
Priority date: 2018-12-27
Filing date: 2019-08-28
Publication date: 2020-07-02
Also published as: EP3904789A4; US20220057130A1; JP6760361B2; EP3904789A1; CN113227681A; JP2020106212A; EP3904789B1

Abstract

Provided is an operation control method for an ice maker 1 that generates ice by cooling a medium to be cooled through heat exchange with a refrigerant. When the drive current of an ice scraping unit 15 included in the ice maker 1 exceeds a first current value, the evaporation temperature of the refrigerant supplied to the ice maker 1 is increased.

Description

Operation control method of ice machine

The present disclosure relates to an operation control method of an ice making machine. More specifically, the present invention relates to an operation control method for an ice maker that produces a sherbet-like ice slurry.

Sherbet-like ice slurry may be used to refrigerate fish. As an apparatus for producing such ice slurry, a double-tube type ice making machine including an inner tube and an outer tube has been conventionally known (for example, refer to Patent Document 1). An ice making system provided with such an ice making machine has a tank for containing a cooled medium such as seawater, and the cooled medium supplied from the tank to the inner pipe of the ice making machine is the outer pipe of the ice making machine. Ice slurry is generated by heat exchange with the refrigerant supplied to the annular space with the inner pipe, and the generated ice slurry is returned to the tank.

Patent No. 3888789

In the ice making system equipped with the ice making machine as described above, if the ice filling rate IPF (Ice Packing Factor), which is the ratio of ice stored in the tank (ice/(ice+medium to be cooled)), becomes too large, Since the piping of the ice making system is clogged and the ice making efficiency is lowered, the ice filling rate in the tank is kept within a certain range. Therefore, conventionally, the amount of ice making in the tank is estimated using a water level sensor, an ultrasonic sensor, or the like provided in the tank, and the operation of the ice making machine is controlled based on the estimated amount of ice making.

However, the ice-making machine in the above-mentioned ice-making system controls the operation of the ice-making machine, which is an element on the equipment side, based on the operation command from the sensor attached to the tank, which is an element on the equipment side. Therefore, the reliability of the operation control of the ice making machine may be deteriorated due to the communication abnormality with the equipment side or the like.

The present disclosure aims to provide an operation control method for an ice maker that can improve the reliability of operation control.

The operation control method of the ice making machine according to the first aspect of the present disclosure (hereinafter, also simply referred to as “operation control method”) is
(1) An operation control method for an ice maker, which cools a medium to be cooled by heat exchange with a refrigerant to generate ice,
When the drive current of the ice scraper provided in the ice maker exceeds a first current value, the evaporation temperature of the refrigerant supplied to the ice maker is increased.

In the operation control method according to the first aspect of the present disclosure, the operation of the ice making machine is controlled based on the current value of the ice scraping section of the ice making machine, which is an element on the device side. For this reason, problems such as communication abnormality with the equipment side as in the past do not occur, and reliability of operation control of the ice making machine can be improved.

(2) In the operation control method of (1) above, the evaporation temperature can be raised stepwise according to the excess of the current. In this case, by increasing the evaporation temperature of the ice scraping unit of the ice making machine step by step in accordance with the excess amount from the first current value, it is possible to suppress the ice production of the ice making machine stepwise.

(3) In the operation control method of (1) or (2), when the drive current exceeds a second current value that is larger than the first current value, the operation of the ice making machine can be stopped.

The operation control method according to the second aspect of the present disclosure,
(4) An operation control method for an ice maker, which cools a medium to be cooled by heat exchange with a refrigerant to generate ice,
When the differential pressure between the pressure at the inlet of the medium to be cooled and the pressure at the outlet of the ice making machine exceeds a first pressure value, the evaporation temperature of the refrigerant supplied to the ice making machine is raised.

In the operation control method according to the second aspect of the present disclosure, the operation of the ice making machine is controlled based on the pressure difference between the pressure at the inlet and the pressure at the outlet of the medium to be cooled in the ice making machine, which is an element on the device side. To do. For this reason, problems such as communication abnormality with the equipment side as in the past do not occur, and reliability of operation control of the ice making machine can be improved.

(5) In the operation control method of (4), the evaporation temperature can be raised stepwise according to the excess of the differential pressure. In this case, the evaporation temperature of the ice making machine is increased stepwise by increasing the evaporation temperature stepwise according to the excess of the differential pressure between the pressure at the inlet and the pressure at the outlet of the cooled medium in the ice making machine from the first pressure value. The generation of ice can be suppressed in stages.

(6) In the operation control method according to (4) or (5), the operation of the ice making machine can be stopped when the differential pressure exceeds a second pressure value that is larger than the first pressure value.

It is a schematic block diagram of an example of an ice making system provided with an ice making machine to which the operation control method of the present disclosure is applied. It is a side surface explanatory view of the ice maker shown in FIG. FIG. 3 is a cross-sectional explanatory view of an ice scraping portion in the ice making machine shown in FIG. 2. It is a figure which shows the example of control of the evaporation temperature in the operation control method which concerns on 1st Embodiment. It is a graph explaining the behavior of the motor current by the operation control method according to the first embodiment. It is a figure which shows the example of control of the evaporation temperature in the operation control method which concerns on 2nd Embodiment.

Hereinafter, the operation control method of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to these exemplifications, and is shown by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

[Ice making system]
First, an example of an ice making system including an ice making machine to which the operation control method of the present disclosure is applied will be described.
1 is a schematic configuration diagram of an ice making system A including an ice making machine 1 to which the operation control method of the present disclosure is applied, and FIG. 2 is a side view of the ice making machine 1 shown in FIG. 1. The ice making system A is a system in which sea water stored in a sea water tank, which will be described later, is used as a raw material to continuously generate ice slurry in the ice making machine 1, and the generated ice slurry is returned to the sea water tank. The ice slurry refers to sherbet-like ice in which fine ice is turbid in water or an aqueous solution, and is also called slurry ice, ice slurry, slurry ice, sraf ice, or liquid ice. The ice making system A can continuously generate an ice slurry based on seawater. Therefore, the ice making system A is installed in, for example, a fishing boat or a fishing port, and the ice slurry returned to the seawater tank is used for keeping cold fresh fish. In the illustrated ice making system A, an amount of new seawater commensurate with the amount of ice slurry used (consumed) is replenished to the seawater tank by a replenishment pump (not shown).

The ice making system A uses seawater as a medium to be cooled, and in addition to the ice making machine 1 that constitutes the use side heat exchanger, a compressor 2, a heat source side heat exchanger 3, a four-way switching valve 4, a use side expansion valve 5, a heat source. A side expansion valve 6, a superheater 7, a receiver 8, a seawater tank (storage tank) 9, and a pump 10 are provided. The ice maker 1, the compressor 2, the heat source side heat exchanger 3, the four-way switching valve 4, the use side expansion valve 5, the heat source side expansion valve 6, the superheater 7, and the receiver 8 constitute a refrigeration apparatus, and these devices are provided. Alternatively, the members are connected by pipes to form a refrigerant circuit. Further, the ice making machine 1, the seawater tank 9, and the pump 10 are also connected by pipes to form a seawater circulation path. In the ice making system A, the ice making machine 1, the compressor 2, the heat source side heat exchanger 3, the four-way switching valve 4, the use side expansion valve 5, the heat source side expansion valve 6, the superheater 7, the receiver 8 and the like are device side elements. The seawater tank 9, the pump 10, the piping, etc. are the equipment-side elements.

Also, the ice making system A includes a control device 30. The control device 30 includes a CPU and memories such as RAM and ROM. The control device 30 realizes various controls relating to the operation of the ice making system A, including the operation control of the present disclosure, by the CPU executing the computer programs stored in the memory.

During normal ice making operation, the four-way switching valve 4 is held in the state shown by the solid line in FIG. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 2 flows through the four-way switching valve 4 into the heat source side heat exchanger 3 which functions as a condenser, and the blower fan 11 operates to exchange heat with the air to condense. Liquefy. The liquefied refrigerant flows into the utilization side expansion valve 5 through the heat source side expansion valve 6 and the receiver 8 in the fully opened state. The refrigerant is depressurized to a predetermined low pressure by the use-side expansion valve 5, and is supplied from an after-mentioned refrigerant inlet pipe into the annular space 14 between the inner pipe 12 and the outer pipe 13 forming the evaporator E of the ice making machine 1. To be done.

The refrigerant jetted into the annular space 14 exchanges heat with the seawater that has flowed into the inner pipe 12 by the pump 10 and evaporates. The seawater cooled by the evaporation of the refrigerant flows out from the inner pipe 12 and returns to the seawater tank 8. The refrigerant evaporated and vaporized by the ice maker 1 is sucked into the compressor 2. At this time, when the refrigerant containing the liquid without being completely evaporated in the ice making machine 1 enters the compressor 2, the compressor 2 malfunctions due to a sudden increase in the pressure inside the compressor cylinder (liquid compression) and a decrease in the viscosity of the refrigerating machine oil. In order to protect the compressor 2, the refrigerant that has left the ice making machine 1 is heated by the superheater 7 and returned to the compressor 2. The superheater 7 is a double pipe type, and the refrigerant that has left the ice making machine 1 is superheated while passing through the space between the inner pipe and the outer pipe of the superheater 7 and returns to the compressor 2.

Also, if the flow of seawater in the inner pipe 12 of the ice making machine 1 is stopped and ice accumulates in the inner pipe 12 (ice accumulation), the ice making machine 1 cannot operate. In this case, a defrost operation (heating operation) is performed to melt the ice in the inner pipe 12. At this time, the four-way switching valve 4 is held in the state shown by the broken line in FIG. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 2 flows into the annular space 14 between the inner pipe 12 and the outer pipe 13 of the ice making machine 1 through the four-way switching valve 4, and the ice inside the inner pipe 12 is cooled. Condenses and liquefies by exchanging heat with seawater containing. The liquefied refrigerant flows into the heat-source-side expansion valve 6 through the use-side expansion valve 5 and the receiver 8 in the fully opened state, is depressurized to a predetermined low pressure by the heat-source-side expansion valve 6, and heat-source-side heat exchange that functions as an evaporator Flows into the vessel 3. During the defrost operation, the refrigerant flowing into the heat source side heat exchanger 3 functioning as an evaporator exchanges heat with air by the operation of the blower fan 11 to be vaporized, and is sucked into the compressor 2.

The ice maker 1 includes an evaporator E including an inner pipe 12 and an outer pipe 13, and an ice scraping portion described later, and the inner pipe 12 and the outer pipe 13 are arranged so that their respective axes are horizontal. It is a horizontal double-tube ice machine. The evaporator E is a liquid-filled evaporator in which most of the annular space 14 between the inner pipe 12 and the outer pipe 13 is a liquid refrigerant, and can improve the heat exchange efficiency between the refrigerant and seawater. Further, by using most of the annular space 14 as the liquid refrigerant, it is possible to easily discharge the refrigerating machine oil in the full-fill type evaporator from the full-fill type evaporator, and the discharged refrigerating machine oil is compressed. By returning to, the lack of lubrication of the compressor 2 can be suppressed and the reliability can be improved.

The inner pipe 12 is an element through which seawater as a medium to be cooled passes, and is made of a metal material such as stainless steel or iron. The inner pipe 12 has a cylindrical shape and is arranged inside the outer pipe 13. Both ends of the inner pipe 12 are closed, and an ice scraping portion 15 for scraping up the sherbet-like ice slurry generated on the inner peripheral surface of the inner pipe 12 and dispersing the ice slurry in the inner pipe 12 is arranged inside the inner pipe 12. It is set up. A seawater inlet pipe 16 for supplying seawater into the inner pipe 12 is provided on one end side (the right side in FIG. 2) of the inner pipe 12 and the other end side (the left side in FIG. 2) of the inner pipe 12 in the axial direction. ) Is provided with a seawater outlet pipe 17 through which seawater is discharged from the inner pipe 12.

The outer tube 13 has a cylindrical shape, and like the inner tube 12, is made of a metal material such as stainless steel or iron. A plurality of (three in the illustrated example) refrigerant inlet tubes 18 are provided in the lower part of the outer tube 13, and a plurality (two in the illustrated example) of the refrigerant outlet tubes 19 are provided in the upper part of the outer tube 13. ing. A refrigerant supply port 20 for supplying the refrigerant into the annular space 14 is formed at the upper end of the refrigerant inlet pipe 18, and a refrigerant discharge port 21 for discharging the refrigerant in the annular space 14 is formed at the lower end of the refrigerant outlet pipe 19. ..

As shown in FIGS. 2 and 3, the ice scraping unit 15 includes a rotating shaft 22, a support bar 23, a blade 24, and a motor 26. The other end of the rotary shaft 22 in the axial direction is provided to extend outward from a flange 25 provided at the other end of the inner tube 12 in the axial direction, and is connected to a motor 26 that constitutes a drive unit that drives the rotary shaft 22. .. The motor 26 includes an ammeter 31, and the drive current of the motor 26 detected by the ammeter 31 is transmitted to the control device 30. Support bars 23 are provided upright on the circumferential surface of the rotary shaft 22 at predetermined intervals, and blades 24 are attached to the tips of the support bars 23. The blade 24 is made of, for example, a strip-shaped member made of synthetic resin, and has a tapered side edge on the front side in the rotation direction.

The annular space 14 formed between the outer peripheral surface of the inner pipe 12 and the inner peripheral surface of the outer pipe 13 causes the refrigerant supply port 20 formed in the lower portion of the outer pipe 13 to reach the upper portion of the outer pipe 13. A refrigerant path is formed to reach the formed refrigerant outlet 21.

[Operation control method]
Next, the operation control method of the ice making machine 1 in the above-mentioned ice making system A will be described. More specifically, an operation control method for changing, stopping or restarting the operating conditions of the ice making machine 1 based on the ice filling rate in the seawater tank 9 will be described.

<First embodiment>
In the ice making system A, when the ice filling rate IPF in the seawater tank 9 increases due to the operation of the ice making machine 1, the amount of ice discharged from the seawater tank 9 increases, and along with this, the ice in the inner pipe 12 of the ice making machine 1 increases. The quantity also increases. When the amount of ice in the inner pipe 12 increases, the driving torque of the motor 26 of the ice scraping unit 15 that scrapes the sherbet-like ice slurry generated on the inner peripheral surface of the inner pipe 12 increases, and The drive current of the motor 26 becomes large. In the first embodiment, the driving current value of the motor 26 of the ice scraping unit 15 is detected by the ammeter 31, and the current value transmitted from the ammeter 31 to the control device 30 is used to measure the ice making machine 1. Perform operation control.

When the ice filling rate IPF of the seawater in the seawater tank 9 increases and the ice is excessively stored in the seawater tank 9 as described above, seawater containing a large amount of ice flows into the ice making machine 1 to scrape the ice. The current value of the motor 26 of the taker 15 increases as compared to the normal value. In the first embodiment, when the current of the motor 26 exceeds the first current value, the evaporation temperature of the refrigerant supplied to the ice making machine 1 is raised.

FIG. 4 is a diagram showing an example of controlling the evaporation temperature in the operation control method according to the first embodiment. In FIG. 4, the vertical axis represents the multiplying factor of the evaporation temperature of the refrigerant in the evaporator E and represents the ratio to the normal evaporation temperature described later. In this control example, the evaporation temperature is set to a normal set temperature t0 (for example, −15° C.) until the current value detected by the ammeter 31 is 6A. Then, in the present embodiment, when the current value exceeds 6 A as the first current value, the evaporation temperature of the refrigerant supplied to the evaporator E is raised. More specifically, in the present embodiment, the evaporation temperature is set high stepwise according to the excess of the current. For example, if the current value is in the range of more than 6A and 7A or less, the operation is controlled so that the evaporation temperature becomes 0.9 times the normal evaporation temperature t0, and the current value further exceeds 7A and 8A or less. Within the range, the operation is controlled so that the evaporation temperature becomes 0.8 times the normal evaporation temperature t0. In this way, the amount of ice making of the ice making machine 1 is reduced by setting the evaporation temperature higher than the normal value in accordance with the increase of the current value.

In the present embodiment, when the current value further increases and exceeds the second current value (11A in this example) which is larger than the first current value, the forced thermostat is turned off and the operation of the ice making machine 1 is stopped. That is, the operation of the compressor 2 is stopped and the circulation of the refrigerant in the refrigerant circuit is stopped. The operation of the ice scraping unit 15 is continued even when the forced thermostat is turned off. After the forced thermo-off, when the current value of the motor 26 drops to a constant value, for example, 9 A, the forced thermo-off is released and the operation of the compressor 2 is restarted.

FIG. 5 is a graph illustrating the behavior of the current value when the operation control according to the first embodiment is performed and when the operation control is not performed (prior art). In FIG. 5, the horizontal axis represents time (t) and the vertical axis represents the current value (A) of the motor 26 of the ice scraping unit 15.
In the prior art, since the operation control is not performed, the drive current of the motor 26 suddenly increases when the ice filling rate IPF increases with the passage of time and the amount of ice in the inner pipe 12 exceeds a certain amount. When the drive current exceeds the predetermined value A1, the overcurrent protection device operates and the operation of the motor 26 is stopped. In this case, since the motor 26 continues to operate in a high torque state until the operation of the motor 26 is stopped, the blade 24 of the ice scraping unit 15, the support bar 23, and the like may be damaged.

On the other hand, in the operation control according to the first embodiment, the current value of the motor 26 until the time t1 when the amount of ice in the inner pipe 12 becomes a constant amount is the same as that of the conventional technique. Current value gradually increases. However, as described above, the amount of ice making is reduced by setting the evaporation temperature higher than the normal value in accordance with the increase in the current value, so that the increase in the current value is slower than in the prior art. is there.

Eventually, when the current value of the motor 26 exceeds the second current value of 11 A at the time t2, the thermostat is forcibly turned off and the operation of the ice making machine 1 is stopped. As a result, new ice is not generated even though the ice slurry in the seawater tank 9 is used, so the amount of ice in the inner pipe 12 is gradually reduced, and the drive current of the motor 26 is gradually reduced. Get smaller. When the current value of the motor 26 eventually becomes 9 A or less at time t3, the forced thermo-off is released and the operation of the ice making machine 1 is restarted. When the operation of the ice making machine 1 is restarted, the amount of ice in the inner pipe 12 increases again, and when the current value of the motor 26 exceeds 11 A at time t4, the thermostat is forcibly turned off again and the operation of the ice making machine 1 is stopped.

In the present embodiment, the operation of the ice making machine 1 is controlled based on the electric current value of the motor 26 of the ice scraping unit 15 of the ice making machine 1 which is an element on the device side. Therefore, the reliability of the operation control of the ice making machine 1 can be improved regardless of the occurrence of a problem such as a communication abnormality with the equipment side as in the related art. This can further reduce the risk of damage to the blade 24 of the ice scraping unit 15 and the support bar 23 due to excessive ice making, and improve the reliability of the ice making system A as a system.

Further, in the present embodiment, the evaporation temperature is raised stepwise in accordance with the excess of the current from the first current value, whereby the ice production of the ice making machine 1 can be restrained stepwise.

<Second Embodiment>
In the present embodiment, as the amount of ice in the inner pipe 12 of the ice maker 1 increases, the pressure loss of seawater moving from the inlet portion to the outlet portion in the inner pipe 12 increases, and the ice maker The operation control of 1 is performed. Specifically, in the present embodiment, when the differential pressure between the pressure at the inlet of seawater (medium to be cooled) in the ice making machine 1 and the pressure at the outlet of the ice making machine 1 exceeds the first pressure value, The evaporation temperature of the refrigerant supplied to the ice maker 1 is raised. In the second embodiment, the pressure of seawater in the seawater inlet pipe 16 and the seawater outlet pipe 17 of the ice making machine 1 is detected by the pressure sensors 32 and 33 (see FIG. 2), respectively, and the

pressure sensor

32, 33 causes the control device 30 to operate. The operation value of the ice making machine 1 is controlled by using the pressure value transmitted to the.

FIG. 6 is a diagram showing an example of controlling the evaporation temperature in the operation control method according to the second embodiment. In FIG. 6, the vertical axis is the magnification of the evaporation temperature of the refrigerant in the evaporator E and represents the ratio to the normal evaporation temperature described later. In this control example, the pressure difference between the pressure of seawater in the seawater inlet pipe 16 detected by the pressure sensor 32 and the pressure of seawater in the seawater outlet pipe 17 detected by the pressure sensor 33 evaporates up to 0.03 MPa. The temperature is set to a normal set temperature t0 (for example, -15°C). Then, in the present embodiment, when the differential pressure exceeds 0.03 MPa as the first pressure value, the evaporation temperature of the refrigerant supplied to the evaporator E is raised. More specifically, in the present embodiment, the evaporation temperature is set high stepwise according to the excess of the differential pressure. For example, when the differential pressure is in the range of more than 0.03 MPa and 0.04 MPa or less, the operation is controlled so that the evaporation temperature becomes 0.9 times the normal evaporation temperature t0, and the differential pressure is further reduced to 0. When it is in the range of more than 04 MPa and 0.05 MPa or less, the operation is controlled so that the evaporation temperature becomes 0.8 times the normal evaporation temperature t0. In this way, the amount of ice making is reduced by setting the evaporation temperature higher than the normal value in accordance with the increase in the differential pressure.

In the present embodiment, when the differential pressure further increases and exceeds the second pressure value which is larger than the first pressure value, the forced thermostat is turned off and the operation of the ice making machine 1 is stopped. That is, the operation of the compressor 2 is stopped and the circulation of the refrigerant in the refrigerant circuit is stopped. The operation of the ice scraping unit 15 is continued even when the forced thermostat is turned off. After the forced thermo-off, the forced thermo-off is released when the differential pressure drops to a constant value, for example, 0.06 MPa, and the operation of the compressor 2 is restarted.

In the present embodiment, the ice making machine 1 is based on the pressure difference between the pressure of the seawater (medium to be cooled) in the seawater inlet pipe 16 and the pressure of the seawater in the seawater outlet pipe 17 in the ice making machine 1, which is an element on the equipment side. Control the operation of. Therefore, the reliability of the operation control of the ice making machine 1 can be improved regardless of the occurrence of a problem such as a communication abnormality with the equipment side as in the related art. This can further reduce the risk of damage to the blade 24 of the ice scraping unit 15 and the support bar 23 due to excessive ice making, and improve the reliability of the ice making system A as a system.

Further, in the present embodiment, the evaporation temperature is raised stepwise in accordance with the excess of the differential pressure from the first pressure value, whereby the ice production of the ice making machine 1 can be restrained stepwise. ..

[Other modifications]
The present disclosure is not limited to the embodiments described above, and various modifications can be made within the scope of the claims.
For example, in the above-described embodiment (first embodiment), the first current value of the motor and the second current value larger than the first current value are 6A and 11A, respectively, but these are merely examples. Of course, the present disclosure is not limited to these current values. The first current value and the second current value can be appropriately selected based on the scale of the ice scraping unit, the characteristics of the motor, and the like.
Similarly, in the above-described embodiment (second embodiment), the first pressure value and the second pressure value larger than the first pressure value are 0.03 MPa and 0.08 MPa, respectively. By way of example only, the present disclosure is not limited to these pressure values. The first pressure value and the second pressure value can be appropriately selected based on the scale of the ice scraping unit, the characteristics of the pump, and the like.

Further, in the above-described embodiment (first embodiment), when the current value of the motor drops to 9 A, the forced thermo-off is released and the operation of the compressor is restarted. The selection is not limited, and can be appropriately selected based on the scale of the ice scraping unit, the characteristics of the motor, and the like.
Similarly, in the above-described embodiment (second embodiment), when the differential pressure at the inlet/outlet of the ice making machine decreases to 0.06 MPa, the forced thermo-off is released and the compressor operation is restarted. The differential pressure is not limited to this, and can be appropriately selected based on the scale of the ice scraping unit, the characteristics of the pump, and the like.

Also, in the above-described embodiment, the evaporation temperature is raised stepwise according to the excess of the current or the differential pressure, but it is also possible to raise the evaporation temperature linearly according to the excess. Further, in the above-described embodiment, the evaporation temperature is raised stepwise according to the excess of the current or the differential pressure. However, when the current or the differential pressure exceeds the first current value or the first pressure value, It is also possible to raise the evaporation temperature by a preset temperature.

Further, in the above-described embodiment (second embodiment), the pressure sensor 32 for detecting the seawater pressure at the inlet of the ice making machine 1 is provided in the seawater inlet pipe 16, but this pressure sensor 32 is provided in the evaporator E. It suffices if the pressure of seawater before heat exchange with the refrigerant can be detected, and for example, it can be provided at a location S1 (inside the inner pipe 12) indicated by a two-dot chain line in FIG. The same applies to the pressure sensor 33 that detects the seawater pressure at the outlet of the ice maker 1, and the pressure sensor 33 may be provided, for example, at a location S2 (inside the inner pipe 12) indicated by a two-dot chain line in FIG. it can.

Further, in the above-described embodiment, as the evaporator E, a liquid-filled evaporator in which most of the annular space 14 between the inner pipe 12 and the outer pipe 13 is a liquid refrigerant has been exemplified. It is also possible to use an evaporator of the type in which the refrigerant is jetted by a nozzle into the annular space 14 between the outer tube 13 and the outer tube 13.

1: Ice machine 2: Compressor 3: Heat source side heat exchanger 4: Four way switching valve 5: Use side expansion valve 6: Heat source side expansion valve 7: Superheater 8: Receiver 9: Seawater tank 10: Pump 11: Blower Fan 12: Inner pipe 13: Outer pipe 14: Annular space 15: Ice scraping part 16: Seawater inlet pipe 17: Seawater outlet pipe 18: Refrigerant inlet pipe 19: Refrigerant outlet pipe 20: Refrigerant supply port 21: Refrigerant discharge port 22 : Rotating shaft 23: Support bar 24: Blade 25: Flange 26: Motor 30: Controller 31: Ammeter 32: Pressure sensor 33: Pressure sensor A: Ice making system E: Evaporator

Claims

An operation control method for an ice maker (1), which cools a medium to be cooled by heat exchange with a refrigerant to generate ice,
An ice making machine (which raises the evaporation temperature of the refrigerant supplied to the ice making machine (1) when the drive current of the ice scraping section (15) provided in the ice making machine (1) exceeds a first current value. The operation control method of 1).
The operation control method according to claim 1, wherein the evaporation temperature is raised stepwise according to the excess of the electric current.
The operation control method according to claim 1 or 2, wherein when the drive current exceeds a second current value that is larger than the first current value, the operation of the ice making machine (1) is stopped.
An operation control method for an ice maker (1), which cools a medium to be cooled by heat exchange with a refrigerant to generate ice,
The evaporation temperature of the refrigerant supplied to the ice making machine (1) when the pressure difference between the pressure at the inlet and the pressure at the outlet of the cooled medium in the ice making machine (1) exceeds a first pressure value. A method for controlling the operation of the ice maker (1) for raising the temperature.
The operation control method according to claim 4, wherein the evaporation temperature is raised stepwise according to the excess of the differential pressure.
The operation control method according to claim 4 or 5, wherein when the differential pressure exceeds a second pressure value that is higher than the first pressure value, the operation of the ice making machine (1) is stopped.