JP2020026924A - Operation control method for ice maker - Google Patents

Abstract

To provide an operation control method for an ice maker that can omit a dedicated sensor for controlling an ice packing factor.SOLUTION: An operation control method for an ice maker 1 for generating ice by cooling a medium to be cooled by exchanging heat with a refrigerant is provided. A temperature of the medium to be cooled at an inlet of the ice maker 1 is detected, and operation of the ice maker 1 is turned on and off on the basis of an ice packing factor calculated from a concentration of a circulating medium to be cooled calculated from the detected temperature of the medium to be cooled in accordance with a predetermined formula, and an initial concentration of the medium to be cooled at the start of ice making.SELECTED DRAWING: Figure 1

Description

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

  In some cases, a sherbet-shaped ice slurry is used to refrigerate fish and the like. As an apparatus for producing such an ice slurry, a double-pipe ice maker provided with, for example, an inner pipe and an outer pipe is known (for example, see Patent Document 1). The ice making system provided with such an ice maker has a tank that stores a medium to be cooled such as seawater, and the medium to be cooled supplied from the tank to the inner tube of the ice maker is connected to the outer tube of the ice maker. Ice slurry is generated by heat exchange with the refrigerant supplied to the annular space with the inner tube, and the generated ice slurry is returned to the tank.

Patent No. 3888789

  In the ice making system provided with the ice making machine as described above, if the ice filling factor IPF (Ice Packing Factor), which is the ratio of ice contained in the tank (ice / (ice + cooling medium)), becomes too large, Since clogging occurs in the piping of the ice making system and the ice making efficiency is reduced, the ice filling rate in the tank is kept within a certain range. Therefore, conventionally, the amount of ice making in the tank has been estimated using a dedicated sensor such as a water level sensor or an ultrasonic sensor provided in the tank. In the present specification, the “dedicated sensor” refers to a dedicated sensor for IPF control, such as a water level sensor and an ultrasonic sensor, used in a conventional ice making system, and will be described later. It does not include a temperature sensor as a means for detecting the temperature in the embodiment.

  However, the above-mentioned water level sensor and ultrasonic sensor are expensive, and especially in a small-scale ice making system such as a fishing boat, the cost ratio of the sensor is large, and measures for it are desired.

  An object of the present disclosure is to provide an operation control method of an ice maker that can omit a dedicated sensor for controlling an ice filling rate.

The operation control method of the ice making machine of the present disclosure (hereinafter, also simply referred to as “operation control method”)
(1) An operation control method for an ice making machine that generates ice by cooling a medium to be cooled by heat exchange with a refrigerant,
The temperature of the cooling medium at the inlet of the ice making machine is detected, and the concentration of the circulating cooling medium calculated from the detected temperature of the cooling medium according to a predetermined formula, and the concentration of the initial cooling medium at the start of ice making. The operation of the ice making machine is turned on / off based on the ice filling rate calculated from the above.

  In the operation control method according to the present disclosure, by detecting the temperature of the cooling medium at the inlet of the ice making machine, the concentration of the circulating cooling medium calculated from the temperature and the concentration of the initial cooling medium determined in advance are determined. From this, the ice filling rate can be calculated, and the operation of the ice making machine is stopped or restarted based on the calculated ice filling rate. A means (for example, a temperature sensor) for detecting the temperature of the medium to be cooled at the inlet of the ice maker is also provided in a conventional ice maker in order to control the operation of the ice maker including controlling the evaporation temperature of the refrigerant. Therefore, the operation control method of the present disclosure can be executed without providing a dedicated sensor for IPF control. In other words, a dedicated sensor for IPF control, such as a water level sensor and an ultrasonic sensor, used in the conventional ice making system can be omitted.

  (2) In the operation control method of (1), when the calculated ice filling rate reaches a predetermined upper limit, the operation of the ice making machine is stopped, and the calculated ice filling rate reaches a predetermined lower limit. Then, the operation of the ice maker can be restarted. In this case, the ice maker can be operated so as to be within the range of the preset ice filling rate.

(3) In the operation control method according to the above (1) or (2), the cooling medium is seawater, and the predetermined equation is that the detected temperature of the cooling medium is Ti (° C.), Assuming that the concentration of the cooling medium is C (wt%),
Ti = -3700 × C / {58.5 × (100-C)}
It can be. In this case, the concentration of the circulating cooling medium can be calculated from the temperature of the cooling medium (seawater) according to a predetermined formula.

(4) In the operation control method according to any one of (1) to (3), the ice making machine has an outer tube and an inner tube provided in the outer tube, and allows a medium to be cooled to flow through the inner tube. It is possible to provide a double-pipe type ice making machine for flowing a refrigerant into a space between the inner pipe and the outer pipe. In this case, the ice filling rate can be controlled by omitting the dedicated sensor for calculating the ice filling rate.

1 is a schematic configuration diagram of an example of an ice making system including an ice machine to which an operation control method according to an embodiment of the present disclosure is applied. FIG. 2 is an explanatory side view of the ice making machine shown in FIG. 1. FIG. 3 is an explanatory sectional view of a blade mechanism in the ice making machine shown in FIG. 2. It is a schematic diagram for demonstrating the relationship between an ice filling rate and seawater concentration.

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

[Ice making system]
First, an example of an ice making system including an ice machine to which the operation control method according to the present disclosure is applied will be described.
FIG. 1 is a schematic configuration diagram of an ice making system A including an ice making machine 1 to which an operation control method according to an embodiment of the present disclosure is applied, and FIG. 2 is a side view of the ice making machine 1 shown in FIG. FIG. The ice making system A is a system in which ice slurry is continuously generated by the ice maker 1 using seawater stored in a seawater tank described later as a raw material, and the generated ice slurry is returned to the seawater tank. The ice slurry refers to sherbet-like ice in which fine ice is turbid in water or an aqueous solution, and is also referred to as slurry ice, ice slurry, slurry ice, sluff ice, and liquid ice. The ice making system A can continuously generate an ice slurry based on seawater. For this reason, 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 fresh fish cool.

  The ice making system A uses seawater as a medium to be cooled, and in addition to the ice making machine 1 constituting 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 refrigerating apparatus. Alternatively, the members are connected by piping to form a refrigerant circuit. The ice maker 1, the seawater tank 9, and the pump 10 are also connected by piping to form a seawater circulation path.

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

  During a normal ice making operation, the four-way switching valve 4 is maintained in a state shown by a solid line in FIG. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 2 flows into the heat source side heat exchanger 3 functioning as a condenser via the four-way switching valve 4, and exchanges heat with air by the operation of the blower fan 11 to condense and condense. Liquefy. The liquefied refrigerant flows into the use-side expansion valve 5 via the heat-source-side expansion valve 6 and the receiver 8 in the fully opened state. The refrigerant is decompressed to a predetermined low pressure by the use-side expansion valve 5 and supplied from a refrigerant inlet pipe, which will be described later, into the annular space 14 between the inner pipe 12 and the outer pipe 13 constituting the evaporator E of the ice making machine 1. Is done.

  The refrigerant jetted into the annular space 14 exchanges heat with seawater flowing into the inner pipe 12 by the pump 10 and evaporates. The seawater cooled by the evaporation of the refrigerant flows out of the inner pipe 12 and returns to the seawater tank 8. The refrigerant evaporated and vaporized in the ice making machine 1 is sucked into the compressor 2. At that time, when the refrigerant containing liquid without being completely evaporated by the ice making machine 1 enters the compressor 2, the compressor 2 fails 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. Therefore, the refrigerant that has exited the ice maker 1 in order to protect the compressor 2 is heated by the superheater 7 and returned to the compressor 2. The superheater 7 is of a double tube type, and the refrigerant exiting the ice making machine 1 is superheated while passing through the space between the inner tube and the outer tube of the superheater 7 and returns to the compressor 2.

  In addition, when the flow of seawater in the inner pipe 12 of the ice maker 1 is interrupted and ice is accumulated in the inner pipe 12 (ice accumulation), the ice maker 1 cannot be operated. 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 maintained 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 via the four-way switching valve 4, and the ice in the inner pipe 12. Condensed and liquefied by heat exchange with seawater containing. The liquefied refrigerant flows into the heat-source-side expansion valve 6 via the use-side expansion valve 5 and the receiver 8 in the fully-open state, and is depressurized to a predetermined low pressure by the heat-source-side expansion valve 6, and the heat-source-side heat exchange functioning as an evaporator It 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, is vaporized, and is sucked into the compressor 2.

  The ice making machine 1 is provided with an evaporator E including an inner tube 12 and an outer tube 13 and a blade mechanism described later. It is a standing type double tube ice maker. 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 used as a liquid refrigerant, and can increase the heat exchange efficiency between the refrigerant and seawater. Further, by making most of the annular space 14 a liquid refrigerant, the refrigerating machine oil in the liquid-filled evaporator can be easily discharged from the liquid-filled evaporator. By returning to, the insufficient lubrication of the compressor 2 can be suppressed, and the reliability can be improved.

  The inner tube 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 tube 12 has a cylindrical shape and is disposed inside the outer tube 13. Both ends of the inner tube 12 are closed, and a blade mechanism 15 for scraping the sherbet-like ice slurry generated on the inner peripheral surface of the inner tube 12 and dispersing the same in the inner tube 12 is provided therein. ing. A seawater inlet pipe 16 through which seawater is supplied into the inner pipe 12 is provided at one axial end (right side in FIG. 2) of the inner pipe 12, and the other axial end of the inner pipe 12 (left side in FIG. 2). ) Is provided with a seawater outlet pipe 17 through which seawater is discharged from the inner pipe 12. A temperature sensor 31 for detecting the temperature of seawater supplied into the inner pipe 12 is provided near the seawater inlet pipe 16 near the connection with the inner pipe 12. The temperature sensor 31 only needs to be able to detect the temperature of seawater before heat exchange with the refrigerant in the evaporator E. It can also be provided.

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

  The blade mechanism 15 includes a rotating shaft 22, a support bar 23, a blade 24, and a motor 26, as shown in FIGS. The other end of the rotating shaft 22 in the axial direction is provided to extend to the outside 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 driving unit that drives the rotating shaft 22. . Support bars 23 are erected at predetermined intervals on the peripheral surface of the rotating shaft 22, and a blade 24 is attached to the tip of the support bar 23. The blade 24 is made of, for example, a band-shaped member made of a synthetic resin, and has a tapered shape at the side edge on the front side in the rotation direction.

  Due to the annular space 14 formed between the outer peripheral surface of the inner tube 12 and the inner peripheral surface of the outer tube 13, a refrigerant supply port 20 formed at a lower portion of the outer tube 13 is connected to an upper portion of the outer tube 13. A refrigerant path to the formed refrigerant outlet 21 is formed.

(Operation control method)
Next, an operation control method of the ice making machine 1 in the ice making system A described above will be described. More specifically, an operation control method for stopping or restarting the operation of the ice maker 1 based on the ice filling rate in the seawater tank 9 will be described.
The “ice filling factor” used in the operation control method of the present disclosure is also referred to as IPF (Ice Packing Factor). If the water level in the seawater tank 9 is constant, the ice making amount (kg) is set to mi, and the supplied seawater amount is set. (Kg) as m0 Ice filling factor IPF = mi / m0
It is represented by Note that the supplied seawater amount is the amount of seawater supplied to the seawater tank in an initial state before ice making.

FIG. 4 is a schematic diagram for explaining the relationship between the ice filling rate and the seawater concentration. The left side shows a seawater tank in an initial state (before ice making), and the right side shows a seawater tank during ice making. The mass of seawater in the initial state is m0 (kg), and the salt concentration of seawater is C0. This C0 (wt%) can be measured in advance. If there is no significant change in the seawater concentration, it can be set as a constant.
If the mass of ice during ice making is mi (kg) and the salt concentration of seawater in the seawater tank 9 at that time is C (wt%), the amount of salt before and after ice making is equal,
m0 · C0 / 100 = (m0−mi) · C / 100
It is. If you transform this,
m0 · C0 = m0 · C−mi · C
(Mi / m0) · C = C−C0 (1)
Becomes Since IPF = mi / m0, dividing both sides of equation (1) by C gives
IPF = (C−C0) / C = 1−C0 / C (2)
If the initial supply seawater concentration and the seawater concentration during ice making (circulating seawater concentration) are known, the ice filling rate IPF can be estimated from equation (2).

In addition, the seawater temperature at the inlet of the icemaker 1 after the ice is generated by the icemaker 1, that is, the seawater temperature (freezing temperature) detected by the temperature sensor 31 provided in the seawater inlet pipe 16 in the present embodiment. And the circulating seawater concentration, the following correlation formula holds, so that the circulating seawater concentration (wt%) can be calculated from the seawater temperature (° C) detected by the temperature sensor 31.
Freezing temperature = -3700 × circulating seawater concentration / {58.5 × (100−circulating seawater concentration)}
・ ・ ・ ・ ・ ・ (3)

If the circulating seawater concentration is known, the IPF can be obtained from the equation (2) from the circulating seawater concentration and a known initial supply seawater concentration.
In other words, if the initial supplied seawater concentration is obtained in advance, the freezing temperature at which the target IPF is reached, that is, the inlet seawater temperature of the ice making machine 1 can be obtained. For example, when the operation of the ice maker is stopped at an IPF of 0.5 and the operation of the ice maker is restarted at an IPF of 0.3, if the supplied seawater concentration is 3.5 wt%, the respective IPFs are equivalent. The freezing temperatures are -4.8C and -3.3C.
Therefore, the seawater temperature is detected by the temperature sensor 31 provided in the seawater inlet pipe 16, and when the temperature becomes lower than −4.8 ° C., the operation of the ice making machine is stopped, and the temperature becomes −3.3 ° C. By restarting the operation of the ice maker when it becomes higher, the IPF can be controlled without providing a dedicated sensor for IPF control in the seawater tank.

  Since the temperature sensor for detecting the inlet seawater temperature of the ice maker 1 is used in the operation control of the ice maker 1 including the control of the evaporation temperature of the refrigerant, it is also provided in the conventional ice maker. The operation control method according to the present embodiment can be executed without providing the dedicated sensor of the present embodiment. In addition, since the IPF can be controlled based on the seawater temperature, a general remote controller for a refrigerating air conditioner having a temperature setting function can be used. In this case, the temperature (freezing temperature) calculated from the known initial seawater concentration and the target IPF value is set as the upper limit temperature and the lower limit temperature by the remote controller.

[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, a so-called scraping-type double-pipe ice maker having an inner pipe and an outer pipe is exemplified as an ice maker that cools seawater as a medium to be cooled and generates ice. However, the present disclosure can be applied to, for example, a supercooled double-pipe ice maker and a harvest-type ice maker other than the double-pipe ice maker.

Further, in the above-described embodiment, the upper limit value and the lower limit value of the IPF are 0.5 and 0.3, respectively, but these values can be appropriately changed and are not particularly limited in the present disclosure. .
In the above-described embodiment, seawater is used as the medium to be cooled. However, the invention is not limited to this, and ethylene glycol, brine, or the like may be used as the medium to be cooled.

1: Ice machine 2: Compressor 3: Heat source side heat exchanger 4: Four-way switching valve 5: Usage side expansion valve 6: Heat source side expansion valve 7: Superheater 8: Receiver 9: Seawater tank 10: Pump 11: Ventilation Fan 12: Inner tube 13: Outer tube 14: Annular space 15: Blade mechanism 16: Seawater inlet tube 17: Seawater outlet tube 18: Refrigerant inlet tube 19: Refrigerant outlet tube 20: Refrigerant supply port 21: Refrigerant discharge port 22: Rotation Shaft 23: Support bar 24: Blade 25: Flange 26: Motor 30: Control device 31: Temperature sensor A: Ice making system E: Evaporator

Claims (4)

An operation control method for an ice making machine (1) for generating ice by cooling a medium to be cooled by heat exchange with a refrigerant,
The temperature of the medium to be cooled at the inlet of the ice making machine (1) is detected, and the concentration of the circulating medium to be calculated calculated from the detected temperature of the medium to be cooled according to a predetermined formula, and the initial cooling at the start of ice making. An operation control method for the ice maker (1), wherein the operation of the ice maker (1) is turned on and off based on an ice filling rate calculated from the concentration of the medium.   The operation of the ice making machine (1) is stopped when the calculated ice filling rate reaches a predetermined upper limit, and the operation of the ice making machine (1) is performed when the calculated ice filling rate reaches a predetermined lower limit. The control method according to claim 1, wherein the control is restarted. The medium to be cooled is seawater, and the predetermined equation is as follows: When the detected temperature of the medium to be cooled is Ti (° C.) and the concentration of the circulating medium to be cooled is C (wt%),
Ti = -3700 × C / {58.5 × (100-C)}
The control method according to claim 1 or 2, wherein   The ice making machine (1) has an outer pipe (13) and an inner pipe (12) provided in the outer pipe (13), and allows a cooling medium to flow through the inner pipe (12). The ice making machine (1) according to any one of claims 1 to 3, wherein the ice making machine (1) is a double-pipe type ice-flowing machine that flows a refrigerant into a space (14) between the inner pipe (12) and the outer pipe (13). The control method described.

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