JPH0777399A - Method and apparatus for controlling brine temperature of brine forcible circulation type refrigerator - Google Patents

Abstract

PURPOSE:To hold a drop of an outlet temperature of a brine cooler and to prevent freezing of the brine by so regulating a liquid injection valve that a detected temperature is held constant when a detected temperature of the outlet temperature of the brine of the cooler is cooled to a step constant-temperature control start setting temperature. CONSTITUTION:A brine outlet temperature detecting sensor 14 is provided at a brine outlet tube of a brine cooler 1, an evaporation pressure detecting sensor 15 and a temperature detecting sensor 16 are provided in a refrigerant outlet tube 1b, sensor signals are input to a controller 17, and an operating amount of a liquid injection valve 13 provided at a refrigerant inlet tube 1a of the cooler is normally calculated based on signals of the sensors 15, 16. On the other hand, when the detected temperature of the sensor 14 becomes a step constant temperature control start setting temperature or lower, an operating amount of the valve 13 is so calculated that the temperature of the sensor 14 is brought into coincidence with the constant temperature control temperature of each step between final arrival temperature from the step constant temperature control start setting temperature, and the valve 13 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brine forced circulation type refrigerating apparatus and a brine temperature control method for the brine forced circulating type refrigerating apparatus, which keeps the outlet temperature of the brine cooler down to near the freezing point of the used brine.

[0002]

2. Description of the Related Art Generally, in a brine forced circulation type refrigerating apparatus, an object to be cooled is housed in a brine tank installed in a circulation line for circulating brine through a brine pump.
Brine having a lower temperature is circulated to remove heat from the object to be cooled for cooling.

Further, the brine, which has been heated to a high temperature in the brine tank by taking heat from the object to be cooled, is cooled by a brine cooler,
It is circulated again in the brine tank and repeatedly takes heat from the object to be cooled.

In the brine cooler, the refrigerant supplied by the liquid injection valve is caused by the difference in the saturated temperature of the refrigerant and the temperature of the object to be cooled through the surface of the heat transfer tube so that the entire cooling area of the heat transfer tube arranged inside the brine cooler works effectively. The liquid and brine are exchanging heat.

Conventionally, as a brine temperature control method and device in this type of refrigeration system, there is a method and device for turning on / off the liquid supply to the brine cooler by using a thermostat.

That is, the control stops the coolant supply to the brine cooler, which is a heat exchanger for the coolant and the brine, when the temperature of the brine drops to the temperature at which the supply of the thermostat for stopping supply of the thermostat is stopped.

On the contrary, when the brine temperature rises to the liquid supply start set temperature of the thermostat, the refrigerant liquid supply to the brine cooler is started, that is, the stop and start are repeated.

[0008]

In the conventional brine forced circulation type refrigerating apparatus, when the brine temperature gradually decreases with the load of the object to be cooled to near the freezing point, the brine passes through the heat transfer tube surface. There is a risk of freezing in the brine cooler because it is constantly in contact with the refrigerant liquid below the freezing point.

Further, in the conventional brine temperature control method and apparatus using a thermostat, the evaporation pressure detection sensor and the temperature detection sensor provided in the refrigerant outlet pipe are used to perform proportional control or proportional-integral control to open the opening of the refrigerant injection valve (injection amount). ) Has been decided and adjusted.

The liquid injection amount is adjusted so that the cooling area of the heat transfer tube in the brine cooler can be effectively used in the brine cooling process.

That is, as described above, since the brine is always in contact with the refrigerant liquid lower than the freezing point of the brine at a considerable portion of the heat transfer tube, there is a drawback that the brine freezes.

Therefore, there is always a risk of breaking the heat transfer tubes in the brine cooler due to freezing of the brine, and it is necessary to set the brine supply set brine temperature considerably higher than the freezing point, and a sufficient cooling effect cannot be obtained. There was a drawback.

An object of the present invention is to provide a brine temperature control method for a brine forced circulation type refrigeration system and a system therefor, which keeps the temperature of the outlet of the brine cooler down to near the freezing point of the used brine and prevents the brine from freezing.

[0014]

In order to achieve the above object, the present invention provides a brine forced circulation type brine refrigerating apparatus for directly or indirectly exchanging heat with an object to be cooled, and a heat exchanger for refrigerant and brine. A brine outlet temperature detection sensor is provided in the brine outlet pipe of a certain brine cooler, and an evaporation pressure detection sensor and a temperature detection sensor are provided in the refrigerant outlet pipe.

An injection valve control unit is provided which inputs signals from the respective sensors of the refrigerant outlet pipe and calculates the operation amount of the liquid injection valve provided in the refrigerant inlet pipe of the brine cooler.

Further, between the step constant temperature control start set temperature and the final reached (lower limit set) temperature, the liquid injection valve is adjusted so that the temperature detected by the brine outlet temperature detection sensor connected to the constant temperature control temperature for each step matches. A constant temperature control unit for calculating the operation amount of is provided.

Next, there is provided a selection unit for inputting the temperature at the brine outlet temperature detection sensor and comparing it with a preset step temperature control start set temperature to select the liquid injection valve control unit and the temperature control unit.

The outputs of the selected liquid injection valve control unit and constant temperature control unit are connected to the liquid injection valve via the liquid injection valve operation unit to connect the liquid injection valve control unit, the constant temperature control unit, the selection unit and the liquid injection valve. The operation unit is used as the controller.

[0019]

When the temperature at the brine outlet temperature detection sensor 14 of the brine cooler reaches the step temperature control start set temperature RSst by the controller 17, the stable state of the temperature at the detection sensor 14 is constantly monitored and set in advance. When it is determined that the temperature is stable at the setting interval T, the constant temperature control start setting temperature is set as an initial setting value, and the constant temperature setting temperature RS is automatically changed stepwise between the temperature and the final (lower limit) setting temperature RSf.

Then, the controller 17 performs the stepwise constant temperature control for adjusting the liquid injection valve 13 of the refrigerant inlet pipe 1a of the brine cooler 1 so that the temperature detected by the brine temperature detection sensor 14 becomes the constant temperature set temperature RS.

That is, when the temperature detected by the brine outlet temperature detection sensor 14 of the brine cooler is cooled to the preset constant temperature control start set temperature set higher than the freezing point in advance, liquid injection is performed so as to keep the detected temperature constant. The valve 13 is adjusted.

When this constant temperature control is entered, the amount of refrigerant supplied to the brine cooler 1 decreases in order to keep the brine outlet temperature, which has been continuously lowered with time, constant.

At the same time, in the brine tank 5, the amount of heat that can be taken from the cooled body 6 becomes smaller due to the difference in temperature between the brine temperature and the cooled body 6, and the refrigerant liquid for keeping the brine outlet temperature constant. The supply will decrease.

As a result, the refrigerant liquid reaching portion in the heat transfer tube 3 moves from the outlet portion to the inlet portion of the heat transfer tube 3 as the evaporation area required for the evaporation of the refrigerant liquid decreases. ,
The time for which the brine comes into contact with the refrigerant liquid via the heat transfer tube surface is shortened, and the risk of the brine freezing in the brine cooler is reduced.

Further, only when the state in which the brine temperature is stable continues for the preset interval time T,
The constant temperature control set temperature RS is automatically changed to a slightly lower value, and is adjusted to the final temperature control final reached (lower limit setting) temperature RSf.

Further, when the brine temperature is lower than a temperature preset with reference to the constant temperature control temperature RS, it is judged that there is a risk of freezing of the brine, and the constant temperature control set temperature RS is automatically set to a high value one step before. The supply of the refrigerant liquid is temporarily stopped until the brine outlet temperature is raised by one step and becomes equal to or higher than the automatically changed constant temperature set temperature, and when the temperature is equal to or higher than the temperature, the constant temperature control is restarted.

Therefore, the brine is directly heat-exchanged with the body to be cooled 6 in the brine tank 5, and the brine is frozen even when the refrigerating device is used such that the brine freezing point rises due to mixing of body fluid and water from the body to be cooled 6. You can avoid the danger of.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description will be given of the accompanying drawings showing an example of the embodiment of the present invention.

FIG. 1 shows a brine forced circulation type refrigerating apparatus of the present invention, FIG. 2 shows a controller, and FIG. 3 shows changes in temperature detected by a brine outlet temperature detection sensor at each stage of stage constant temperature control with respect to time. Indicates the state of.

Reference numeral 1 denotes a brine cooler, in which a distributor 2 connected to the refrigerant inlet pipe 1a is arranged at one end, a large number of heat transfer pipes 3 are connected to the distributor 2, and a collector 4 is connected to the other end of the heat transfer pipe 3. To the refrigerant outlet pipe 1b.

A brine inlet pipe 7 for supplying brine from a brine tank 5 for containing and cooling the cooled object 6 by a brine pump 8 and the brine are supplied to the brine tank 5.
The brine outlet pipe 9 to be returned to is connected.

Further, the refrigerant gas from the refrigerant outlet pipe 1b is sucked into the compressor 10 to be a high temperature and high pressure refrigerant gas, and the condenser 11
Is condensed to form a high-pressure refrigerant liquid, which is stored in the liquid receiver 12 and circulated in the refrigerant inlet pipe 1a as a low-pressure refrigerant liquid by the liquid injection valve 13.

Reference numeral 14 denotes a brine outlet temperature detection sensor provided in the brine outlet pipe 9, which detects the temperature of the brine cooled by the brine cooler 1 and inputs the detection signal to the controller 17 described later.

Reference numeral 15 denotes an evaporation pressure detection sensor provided in the refrigerant outlet pipe 1b, which inputs the detected pressure to a liquid injection valve control unit 18 described later in the controller 17 to convert it into a refrigerant saturation temperature,
The operation amount of the liquid injection valve 13 is calculated based on the refrigerant temperature detected by the refrigerant outlet temperature detection sensor 16 provided in the same manner.

Reference numeral 17 denotes a controller. When the temperature detected by the brine outlet temperature detection sensor 14 is equal to or higher than the preset constant temperature control start set temperature, the liquid injection valve control section 18 controls the liquid injection valve 13 to control the temperature. When the temperature is lower than the set temperature for starting the stepwise constant temperature control, the constant temperature control unit 19 described later causes the liquid injection valve 1
The control unit 18 and 19 are selected and switched so as to control the control unit 3.

Reference numeral 18 denotes a liquid injection valve control section, which controls the operation amount of the liquid injection valve 13 as described above by means of the respective sensors 15, 15 of the refrigerant outlet pipe 1b.
The liquid injection valve 13 is controlled via a liquid injection valve operating unit 21 which will be described later by calculating based on the signal of 16.

Reference numeral 19 denotes a constant temperature control unit, which detects the temperature detected by the brine outlet temperature detection sensor 14 at the constant temperature control set temperature RS for each step between the step constant temperature control start set temperature RSst and the final reached (lower limit set) temperature RSf. The operation amount of the liquid injection valve 13 is calculated so that

Reference numeral 20 is a selection unit for inputting a signal from the brine outlet temperature detection sensor 14 and connecting the liquid injection valve control unit 18 and constant temperature control unit 19 to the brine outlet temperature detection sensor 1 as described above.
Temperature detected in step 4 and step constant temperature control start set temperature RSst
Is selected and switched by comparing.

Reference numeral 21 denotes a liquid injection valve operation unit, which is connected to the outputs of the liquid injection valve control unit 18 and the constant temperature control unit 19 so that the operation amount calculated by the liquid injection valve control unit 18 and the constant temperature control unit 19 can be obtained. Then, the opening degree of the liquid injection valve 13 is adjusted.

FIG. 3 shows changes in the temperature detected by the brine outlet temperature detection sensor 14 with respect to time in each step of the step temperature control.

When the detected temperature becomes lower than the preset constant temperature control start temperature RSst, the control of the liquid injection valve 13 shifts from the liquid injection valve control unit 18 to the constant temperature control unit 19, and RSst is used as the initial constant temperature control set temperature. To be done.

T is a set interval time for stability judgment of the detected temperature, and the interval time setting timer starts when the vertical fluctuation width D of the detected temperature falls within a certain range ± D / 2 degrees around RSst. To do.

When the timer times out, the constant temperature target temperature (RSst-RS) which is lower than the constant temperature setting temperature RS by one step when the constant temperature set temperature RS is automatically changed step by step.
sp), the set temperature RSst is automatically changed, and the lower limit set temperature (constant temperature control final reached temperature) RSf is automatically changed sequentially.

However, the fluctuation of the detected temperature is ±
When D / 2 or more, the timer is reset and
When the time falls within D / 2 degrees, the interval time setting timer starts operating.

In the LD, the detected temperature is a constant temperature set temperature R.
It is a temperature range in which RS is set and changed to a temperature (RS + RSsp) higher by one step when the temperature falls below the temperature range from S.

Further, when the detected temperature of the RD rises above the step temperature control start set temperature RSst, the liquid injection valve 13 is controlled from the constant temperature control unit 19 to the liquid injection valve control unit 1.
This is the temperature range that shifts to 8.

If the lower limit set temperature RSf is set to the freezing point of the brine, the outlet temperature of the brine cooler can be lowered and maintained near the freezing point of the used brine.

[0048]

Since the present invention has the above-mentioned configuration, when the temperature detected by the brine temperature detecting sensor at the outlet of the brine cooler is cooled to the preset constant temperature control start set temperature which is set higher than the freezing point in advance, The liquid injection valve is adjusted so as to keep the detected temperature constant, and constant temperature control is performed.

When this constant temperature control is entered, the amount of refrigerant supplied to the brine cooler decreases in order to keep the brine outlet temperature, which has been continuously decreasing with time, constant.

On the other hand, in the brine tank, the amount of heat that can be taken from the object to be cooled becomes small due to the difference in temperature between the brine temperature and the object to be cooled, and the supply amount of the refrigerant liquid for keeping the brine outlet temperature constant decreases. Therefore, as the evaporation area required for the refrigerant liquid to evaporate decreases, the refrigerant liquid arrival part in the heat transfer tube moves from the outlet part of the heat transfer tube to the inlet part, so that the brine is transferred to the surface of the heat transfer tube. The time of contact with the refrigerant liquid via the can be shortened, and the risk of freezing in the brine cooler can be reduced.

Further, in the present invention, the constant temperature control set temperature is automatically changed to a slightly lower value and adjusted to the lower limit set temperature (constant temperature control final reached temperature) only when the stable brine temperature continues for a preset interval time. Go away.

When the brine temperature becomes lower than the preset temperature based on the constant temperature control temperature, it is judged that there is a risk of freezing of the brine, and the constant temperature control set temperature is automatically changed to a higher value one step before. At the same time, the supply of the refrigerant liquid is temporarily stopped until the brine outlet temperature rises by one step above the automatically changed constant temperature set temperature, and when the temperature exceeds the temperature, the constant temperature control is restarted.

Therefore, there is a risk of brine freezing even in the use condition of the refrigerating apparatus where the brine directly exchanges heat with the object to be cooled in the brine tank and the brine freezing point rises due to mixing of body fluid and water from the object to be cooled. The brine can be avoided and the brine can be cooled with confidence without freezing of the brine even near the brine freezing point.

[Brief description of drawings]

FIG. 1 is a piping / wiring diagram showing an outline of a brine forced circulation type refrigeration system of the present invention.

FIG. 2 is a block wiring diagram showing details of a controller and connection to a brine forced circulation type refrigeration system.

FIG. 3 is a table showing a state of changes in temperature detected by a brine outlet temperature detection sensor with respect to time in each stage of the stage constant temperature control. 1 Brine Cooler 1a Refrigerant Inlet Pipe 1b Refrigerant Outlet Pipe 2 Distributor 3 Heat Transfer Tube 4 Aggregator 5 Brine Tank 6 Cooled Body 7 Brine Inlet Pipe 8 Brine Pump 9 Brine Outlet Pipe 10 Compressor 11 Condenser 12 Liquid Receiver 13 Liquid Injection valve 14 Brine outlet temperature detection sensor 15 Evaporation pressure detection sensor 16 Refrigerant outlet temperature detection sensor 17 Controller 18 Liquid injection valve control unit 19 Constant temperature control unit 20 Selection unit 21 Liquid injection valve operating unit RS Constant temperature setting temperature RSst stage constant temperature control start setting Temperature RSsp 1 step change temperature range D Detection temperature fluctuation range RSf Lower limit setting temperature LD, RD setting change temperature range T Setting interval

Claims (2)

[Claims] 1. In a brine forced circulation type refrigerating apparatus for directly or indirectly exchanging heat with an object to be cooled, when the temperature at a brine outlet temperature detection sensor of a brine cooler reaches a preset constant temperature control start set temperature, said detection sensor. The temperature is constantly monitored for stability, and if it is stable at a preset setting interval, the constant temperature start set temperature is used as the initial set value and the constant temperature set temperature is gradually increased between that temperature and the final (lower limit) set temperature. Is automatically changed, and stepwise constant temperature control is performed by the controller that adjusts the liquid injection valve of the refrigerant inlet pipe of the brine cooler so that the temperature detected by the brine outlet temperature detection sensor becomes the constant temperature set temperature. The method for controlling the brine temperature of the forced brine circulation type refrigeration system, which is characterized in that the temperature is lowered and maintained near the freezing point of. 2. In a brine forced circulation type refrigerating apparatus for directly or indirectly exchanging heat with an object to be cooled, a brine outlet temperature detection sensor is provided in a brine outlet pipe of a brine cooler as a heat exchanger for refrigerant and brine. Injection valve control in which an evaporating pressure detection sensor and a temperature detection sensor are provided in the refrigerant outlet pipe, and signals from the respective sensors of the refrigerant outlet pipe are input to calculate the operation amount of the liquid injection valve provided in the refrigerant inlet pipe of the brine cooler. Operation of the liquid injection valve so that the temperature detected by the brine outlet temperature detection sensor connected to the temperature control temperature for each stage matches the temperature reached for the final temperature (lower limit setting) A constant temperature control unit that calculates the amount is provided, the temperature at the brine outlet temperature detection sensor is input, and injection valve control is performed by comparing with the preset stage temperature control start set temperature. Section for selecting the temperature control unit and the constant temperature control unit, and a controller for connecting the output of the injection valve control unit and the constant temperature control unit to the liquid injection valve via the liquid injection valve operation unit is provided. Brine temperature controller for circulating refrigeration system.