JPS61205767A - Method of controlling temperature of cold-insulating warehouse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for controlling the temperature of a cold storage box, which allows fresh foods to be stored for a long period of time without impairing their freshness or taste.

Conventional technology and its problems When keeping fresh food cold or refrigerated, in order to maintain its freshness and not lose its taste, it is necessary to keep the temperature of the object to be cooled, especially for live fish, at the temperature just before freezing. It is well known that if the product is kept at a temperature and refrigerated, its freshness will be maintained for a long period of time. Then, since it freezes at -4'C, the temperature just before that is -8±0.5°C.
In order to satisfy this condition, conventional cooling methods operate at a difference of 8 to 4 degrees Celsius between the temperature of the cold air on the suction side and the temperature of the cold air on the discharge side. Therefore, in order to maintain the temperature directly below the freezing point (generally -4'C for fresh fish), the temperature on the discharge side must be (-4'C) -17°C. .

Therefore, the outside surface of the object to be cooled, such as fresh fish, is exposed to cold temperatures below the freezing point (-7'C to -8'C), which has the drawback of freezing the surface of the object and deteriorating its quality.

In order to improve the above-mentioned drawbacks, the following method has been proposed near the storage temperature where the cooling load is reduced.

Pline method to control the O-line flow rate ■ Coalescence control method using an unloader ■ Method of using a heater and cooler together ■ Hot gas bypass method ■ Method of using multiple refrigerators of the same capacity and operating them in combination However, There are advantages and disadvantages in methods such as 1. For example, in method O, the temperature of the pline is kept constant and the flow rate of the pline is controlled to keep the cooling air temperature constant, but it requires complicated control of the pline temperature control and flow rate control. Moreover, the structure is complicated because it requires high concentration management of the prine, refrigerant and prine piping, and a prine tank, which increases the price, and it is difficult to save labor in several types in one unit.

In the method (2), a refrigerator having multiple cylinders is used and the number of operating cylinders is varied (controlled) to control the capacity. For example, for a 4-cylinder model, the operating number and capacity ratio are 4 cylinders operating without unloading, 100 width capacity 8 tons
t 1 cylinder 752 tt
2 cylinder 501 tt
The B cylinder is 25 and the capacity can be controlled, but refrigerators with this type of structure are large (generally several liters of horsepower).
Therefore, it is not suitable for small-sized equipment (it is not suitable for small-sized equipment due to its complicated structure).The difference between the air temperature at the inlet and outlet of general refrigeration equipment can be controlled within 8 to 4'C ± 06°C. is 4
It is necessary to control cylinders and eight or more cylinders, making it impossible for small machines such as 1- or 2-gas machines and small machines that cannot incorporate an unloader mechanism.

(2) The output method is to control the temperature by turning the warmer on and off while cooling, which is a simple device, but wastes energy and is not suitable for practical use.

In the case of hot gas bypass, the capacity is controlled by bypassing the hot gas from the discharge side of the cooling device to the suction side, and the amount of hot gas must be controlled in accordance with the temperature (temperature inside the refrigerator). Moreover, the gas temperature fluctuates depending on the operating conditions, making it unsuitable for precise control.

Furthermore, in order to compensate for the above-mentioned drawbacks of method (■), i.e., capacity control by combining multiple refrigerators, in small to medium-sized facilities, multiple refrigerators are used in combination, and the capacity is controlled to match the load by controlling the number of refrigerators. . However, this device also has a limited range of capacity control. For example, if the control is 20<, the capacity ratio is 20:8
It is a combination of 0 and the size of the incoming material (chilled material) and storage,
There are inconveniences such as the need to change the combination of capital changes due to structure, etc.

Means for Solving Problems The present invention has a structure that is simple and suitable for small to medium-sized equipment.
When storing perishables in cold storage, control is generally performed by sensing the temperature of the suction air. In order to prevent this, the present invention installs and controls a blowout temperature control device that works in conjunction with a suction temperature control device (for example, a thermostand, etc.).

And what is the temperature difference?

Therefore, to perform precise control, increase the air volume by controlling the rotation speed of the blower, which is linked to the blowout temperature control device, which is linked to the suction temperature control device, or control the rotation speed of the refrigerator.

Also, it takes several hours (S
~4hr), the ratio of the refrigeration load during that time to the load after the cold storage set temperature is reached is 10:1 to 2, and the extreme drop in rotational speed of the blower and refrigerator is due to insufficient static pressure inside and outside the machine in the blower. There is a risk that there will be no ventilation in the refrigerator, or that there will be a lack of lubricating oil heat source in the refrigerator. In order to prevent this, two refrigerators are combined and their capacity ratio is set to 1 to 1 or more, and during the time from storage until the set temperature is reached, two refrigerators are operated, and the one with the larger capacity is operated at a temperature higher than the set standard. Stop the table.

Next, operate the smaller capacity refrigerators, and connect each refrigerator to the outlet temperature control device, which is linked to the suction temperature control device.
[5. Also, the small capacity refrigerator is linked to the fan rotation speed. This number is 50< for a commonly used blower.
It is possible to increase or decrease the air volume during the process, and the refrigerator can be operated without any problems.

Embodiment 1 FIG. 2 shows an operating circuit when two refrigerators are used and the rotational speed of the blower is controlled.

In the figure, 1zc1.52cs+ is a refrigerating machine, which may have the same volume or different capacities, preferably different capacities. R2FE is a blower, and this blower sgFE
t2 is connected to an integral operation circuit PID and a frequency wave transformer INV, and -2 and 3 are temperature control subcircuits, and this circuit 21I is connected to a temperature controller THM1 provided on the suction side of the refrigerator (cooler).
and a temperature controller THM2 provided on the outlet side are connected, and the outlet temperature conversion output 0 (output current mA or output voltage V) of the circuit 211 is applied to the integral calculation circuit PID. Temperature control suction THM I TH is installed on the suction side and outlet side of the cooler and detects the respective hot electricity.
M2 is a sensor such as a thermostat, and THMl has the same contact point Y$! , THM11 has two same contacts Y2. Y8, the temperature on the suction side and the temperature on the outlet side are respectively set so that each contact operates at this cooling temperature.

FIG. 1 shows the relationship between time and temperature when an object to be cooled is cooled by a cooling device. [It indicates a temperature slightly higher than tg, that is, a set standard temperature that has changed just before freezing, and the set holding temperature range is ±to before and after this official standard temperature tz, and even in this case, t
20t O>t 8. And the above thermostat THM l is ON when [2+σ,
The thermostat turns off when t2+to.)
Contact Y2 of THM* is ON when tz+tO, tz-t
OFF when o, contact Y8 ON when tz%tBO)
The integral operation circuit PID is set to turn off when the temperature is 1ft2 as shown in Figure 8.
-to has a minimum value of 12 t.

In this case, the blower is set to rotate to the maximum value.

Therefore, the operation of the circuit 1 constructed as described above is as shown in the figure below.

In this figure, if the suction temperature of the cooler is tz (0 or more),
Outlet temperature if t2+t o or more and outlet temperature 1 t2+
In to~-t, the first. The second twin refrigerator is operated, and when the blowout temperature is t2+to2+t, the blower is driven at a predetermined constant rotation speed t11'':S.

When the blowout temperature is between it2+to and -1, the number of revolutions of the blower is lowered to make 8T smaller.

Also, if the rotation speed of the blower increases and the suction temperature decreases regardless of the number of times to reduce ΔT, the first refrigerator 52C
t is stopped and the fan rotation speed changes automatically.
The temperature is maintained at an appropriate temperature by reducing T, and if the load is small and the suction temperature is below t2+to and the outlet temperature is below t8, the second refrigerator is also stopped.

In this case, the blower is operated and maintained at 12-to.

Embodiment 2 As shown in FIG. 8, this is a system in which the rotational speeds of both the blower and the refrigerator are changed, and one of them, for example, the second refrigerator 52C2 is connected to the integral calculation circuit PI in the same manner as the blower I@machine 52FE.
D. Connection of frequency converter INV 1 - The other circuits are the same as the embodiment shown in FIG. This second embodiment and its operation are as shown in the table below.

In the above table, ◯ indicates drive and × indicates stop, and although the cost of the device is a little higher than in the first embodiment, better control from end to end is possible.

Furthermore, in the case of a small capacity, only one refrigerator, that is, the 52CI may be omitted.

In addition, when using two refrigerators, if the respective coolers are alternately combined in the same cooler, the second refrigerator 1i2.
CI! In the case of single-unit operation, a larger heat transfer area can be used, so the evaporation temperature can be kept higher than in the case of two-unit operation, and the temperature difference between the suction port and the outlet is smaller, which is advantageous. In addition, even if frost forms on the surface of the cooler fins due to sub-zero operation, defrosting using hot gas is carried out in one step, which is efficient and requires only one unit.

Effects of the Invention According to the present invention, temperature controllers are installed on the suction port side and the blowout port side of the cooler to control the rotational speed of the blower or the rotational speeds of the blower and refrigerator to control the capacity. Therefore, it has the advantage of being able to easily operate at a blowing temperature above the freezing point and keeping food cold without spoiling its taste.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of temperature control, @2 is an operating circuit diagram, Fig. 8 is a rotation control diagram of the blower, and Fig. 4 is a circuit diagram of the second embodiment. Fis Ct is the first refrigerator, K2CII is the second refrigerator, 52FE is the blower, and llI+ is the temperature controller. Tf (Mx, THMz is the thermostat.

Claims (2)

[Claims] (1) Temperature controllers installed on the inlet and outlet sides of the cooler detect the temperature difference between the suction and outlet, and thereby control the rotation speed of the blower or refrigerator,
A temperature control method for a refrigerator, characterized in that items to be refrigerated are kept cold at a temperature just below the freezing point. (2) A temperature control method for a cold storage box according to claim 1, which uses a plurality of refrigerators having a capacity ratio of 1:1 or more.