JPH0618105A - Refrigerant mixing-ratio detector for refrigerator - Google Patents

Abstract

PURPOSE:To detect the mixing ratio of a mixed refrigerant without depending upon direct measurement, and to enable correction, in which the set value of a protective device for a refrigerator is set at a set value corresponding to the mixing ratio obtained. CONSTITUTION:The temperature and saturation pressure of a mixed refrigerant detected by detectors 21, 22 are inputted to an arithmetic unit 23, and the mixing ratio of the mixed refrigerant is obtained through arithmetic operation from data stored in said arithmetic unit 23, thus allowing the detection of the mixing ratio without direct measurement. The mixing ratio is inputted to a correction circuit 24 from a refrigerant mixing-ratio detector composed of the detectors 21, 22 and the arithmetic unit 23, and the set values of protective devices 13, 14 are corrected in response to the fluctuation of the mixing ratio of the mixed refrigerant by enabling the correction of the set values of the protective devices 13, 14 by said correction circuit 24, thus positively tripping a refrigerator when the refrigerator exceeds the range of proper operating conditions, then ensuring the safety of the refrigerator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a refrigerant mixture ratio of a refrigerator, which is applied to all refrigerant gas compression refrigerators such as a turbo refrigerator, a screw refrigerator, a reciprocating refrigerator and a rotary refrigerator. Regarding

[0002]

2. Description of the Related Art A conventional refrigerator is shown in FIG. In the conventional refrigerator shown in FIG. 3, the refrigerant liquid 11 in the evaporator 5 evaporates by radiating heat from the cold water flowing in the heat transfer pipe 6 of the evaporator 5 to become a refrigerant gas, which is compressed through the refrigerant pipe 10. The gas is sucked into the machine 1, compressed therein, and becomes high-temperature and high-pressure gas and flows into the condenser 2. The refrigerant gas flowing into the condenser 2 is cooled by the cooling water flowing in the heat transfer tube 3 of the condenser 2 and condensed and liquefied to become a refrigerant liquid. Return.

The refrigerant circulated in the refrigeration system in this way is
The cold water 8 flowing in the heat transfer tube 6 of the evaporator 5 receives heat to cool it, and releases this heat to the cooling water 7 flowing in the heat transfer tube 3 in the condenser 2.

Regarding the above-mentioned refrigerator, in order to protect it,
Several security devices are provided, a typical example of which is shown in FIG. The evaporator pressure switch 13 attached to the evaporator 5 is operated when the evaporator pressure becomes abnormally low to trip the refrigerator.

Further, the condenser pressure switch 12 attached to the condenser 2 operates to trip the refrigerator when the condenser pressure becomes abnormally high. Further, the compressor discharge temperature switch 14 attached to the compressor discharge pipe 10 is operated to trip the refrigerator when the compressor discharge temperature becomes abnormally high.

In the meantime, with regard to the refrigerant used in the refrigerator, it has been necessary in recent years to switch from a conventional refrigerant to an alternative refrigerant due to restrictions on the use of CFCs. Regarding the switching from the conventional refrigerant to the alternative refrigerant, it is costly to switch all the amount at once, so the refrigerant component leaked from the refrigerator is supplemented with the alternative refrigerant, and the ratio of the conventional refrigerant in the refrigerant is gradually reduced. Then, a method is adopted in which most of the refrigerant is finally replaced with the alternative refrigerant.

[0007]

In the conventional refrigerating machine, when the leakage of the conventional refrigerant filled in the device is supplemented by the alternative refrigerant and gradually replaced with the alternative refrigerant, the conventional refrigerant is compared with the conventional refrigerant. Since the saturation pressure of the alternative refrigerant is low, the evaporator pressure and the condenser pressure decrease as the ratio of the alternative refrigerant increases, even if the evaporation temperature and the condensation temperature do not change.

For example, when the condensation temperature is 40 ° C., the saturation pressures of the conventional refrigerant and the alternative refrigerant are about 0.8 kg / cm, respectively.
² Abs, about 0.6 kg / cm ² Abs, and the condenser pressure decreases as the ratio is increased by supplementing the alternative refrigerant. The evaporator pressure is similar.

Therefore, if the set value of the condenser pressure switch is left at the value (1 kg / cm ² G) for the conventional refrigerant only, when the ratio of the alternative refrigerant increases, condensation occurs even if an abnormality occurs. In some cases, the refrigerator does not trip due to the vessel pressure.

On the contrary, if the set value of the evaporator pressure switch is left as it is when only the conventional refrigerant is used, when the ratio of the alternative refrigerant increases, there is a case where the trip occurs due to the evaporator pressure even if there is no abnormality. Occur.

Further, even if the refrigerator is operated under the same conditions due to the characteristics of the refrigerant, the discharge temperature of the compressor decreases with an increase in the ratio of the alternative refrigerant. If left as it is, if the ratio of the alternative refrigerant increases, a case may occur in which the compressor discharge temperature does not trip even if an abnormality occurs.

In order to solve the above problems, the present invention aims to provide a device capable of automatically adjusting the set value of each protection device.

[0013]

[Means for Solving the Problems]

(1) A refrigerating machine refrigerant mixing ratio detecting device of the present invention comprises a detecting device for detecting a temperature and a saturation pressure of a mixed refrigerant used by mixing two types of non-azeotropic refrigerants, and a refrigerant detecting device for detecting a refrigerant from the detecting device. It is characterized in that it is provided with an arithmetic unit for inputting temperature and saturation pressure to obtain a mixing ratio of two kinds of refrigerants.

(2) The refrigerator of the present invention is the above-mentioned invention (1).
The refrigerant mixture ratio detecting device described in (1) is provided, and a correction circuit for correcting the set value of the safety device of the refrigerator by inputting the mixture ratio of the mixed refrigerant from the detecting device is characterized.

[0015]

In the above invention (1), regarding the mixed refrigerant in which two kinds of refrigerants are mixed, there is a constant relationship between the temperature, the saturation pressure and the mixing ratio, and this data is stored in the arithmetic unit. There is. Therefore, the arithmetic device, when inputting the temperature and the saturation pressure of the mixed refrigerant detected by the detection device,
The mixing ratio of the refrigerant is detected using the above data.

As described above, it becomes possible to detect a mixed refrigerant in which two kinds of refrigerant are mixed without directly measuring the mixing ratio.

In the above invention (2), the above invention (1)
The mixing ratio of the mixed refrigerant output from the refrigerant mixing ratio detecting device is input to the correction circuit, and the correction circuit sets the set values such as the evaporator pressure and the compressor discharge temperature set in the safety device to the mixing ratio of the mixed refrigerant. Correct to a proper value corresponding to.

As described above, since the set value of the safety device is corrected according to the change of the mixing ratio of the mixed refrigerant, the refrigerator surely trips when it exceeds the range of the proper operating condition, and the safety of the refrigerator is ensured. It

[0019]

FIG. 1 shows an embodiment of the present invention. In the present embodiment shown in FIG. 1, a compressor 1, driven by a motor 9, and a condenser 2, a refrigerant flow rate control device 4, and an evaporator 5, which are sequentially connected to each other, form a refrigerant cycle. A compressor discharge temperature switch 14 is provided on the refrigerant pipe 10 between the two.
In the refrigerator in which the evaporator 5 is provided with the evaporator pressure switch 13, the temperature detection device 21 and the saturation pressure detection device 22 and the temperature detection device 21 and the saturation pressure detection device provided in the evaporator 5 are provided. 22 is connected via an electric wire, and a correction circuit 24 that is connected to the arithmetic device 23 and outputs correction signals of set values to the evaporator pressure switch 13 and the compressor discharge temperature switch 14 for correction. Is equipped with. The refrigeration cycle in this embodiment is the same as that of the conventional device, and therefore its detailed description is omitted.

In the above, the temperature detecting device 21 and the saturation pressure detecting device 22 provided in the evaporator 5 detect the temperature and the saturation pressure of the refrigerant liquid 11 in the evaporator 5, and input them to the arithmetic unit 23.

When the refrigerant liquid 11 is a mixture of two kinds of refrigerant, there is a relationship shown in FIG. 3 between the mixing ratio of the two kinds of refrigerant, the temperature of the refrigerant and the saturation pressure of the refrigerant. That is,
When the temperature of the refrigerant is t ₁ ° C, the saturation pressure changes according to the mixing ratio of the refrigerant as shown by the curve CXD. Also t ₂
In the case of ° C, the saturation pressure changes like the curve EF according to the mixing ratio of the refrigerant.

Therefore, the refrigerant mixture ratio at that time can be obtained by applying the temperature and saturation pressure detected by the refrigerant temperature detecting device 21 and the refrigerant saturation pressure detecting device 22 provided in the refrigerator to FIG. For example, when the temperature is t ₁ ° C and the saturation pressure is P _X , the mixing ratio Y% can be obtained from the intersection X of the curve CXD and the pressure P _X.

In this embodiment, data showing the relationship between the temperature of the refrigerant, the saturation pressure and the mixing ratio shown in FIG. 3 is stored, and the temperature detecting device 21 and the saturation pressure detecting device 22 are stored.
The arithmetic unit 23 in which the temperature and saturation pressure of the refrigerant are input more
Calculates the mixing ratio of the refrigerant using the above data and inputs it to the correction circuit 24.

Correction circuit 2 in which the mixing ratio of the above refrigerant is input
Numeral 4 obtains an appropriate value corresponding to the mixing ratio of the refrigerant among the set values of the evaporator pressure switch 13 and the compressor discharge temperature switch 14 which are safety devices, and the respective switches 1
Correct the set values of 3 and 14 to appropriate values.

According to the above, the mixing ratio of the refrigerant can be obtained without directly measuring, and the set value of the safety device is corrected based on this, so that when the leakage of the conventional refrigerant is supplemented by the alternative refrigerant, Became able to drive without problems.

Further, when the refrigerant is temporarily taken out of the refrigerator for inspection or overhaul, a part of the refrigerant is vaporized and escapes to the atmosphere. Therefore, if it is replenished, the mixing ratio of the refrigerant may change. However, even in such a case, the operation of the refrigerator can be restarted without any special treatment.

In the present embodiment, the evaporator is set as a position where the temperature of the refrigerant and its saturation pressure can be detected at the same time. If it can be accurately detected, it may be detected from other parts.

[0028]

According to the refrigerant mixing ratio detecting device for a refrigerator of the present invention, the temperature and the saturation pressure of the mixed refrigerant detected by the detecting device are input to the arithmetic unit, and the mixed refrigerant is detected from the data stored in the arithmetic unit. By calculating the mixing ratio by calculation, the mixing ratio can be detected without directly measuring it.

Further, by inputting the mixing ratio into the correction circuit from the refrigerant mixing ratio detecting device and enabling correction of the setting value of the security device by the correction circuit, the setting value of the security device becomes the mixing ratio of the mixed refrigerant. Is corrected in accordance with the fluctuation of the above condition, the refrigerating machine will certainly trip when exceeding the range of the proper operating condition, and the safety of the refrigerating machine can be secured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is a relationship diagram showing a relationship among a temperature, a saturation pressure, and a mixing ratio of the mixed refrigerant according to the above one embodiment.

FIG. 3 is an explanatory diagram of a conventional refrigerator.

[Explanation of symbols]

 1 Compressor 2 Condenser 4 Refrigerant flow control device 5 Evaporator 13 Evaporator pressure switch 14 Compressor discharge temperature switch 21 Temperature detection device 22 Saturation pressure detection device 23 Arithmetic device 24 Correction circuit

Claims (2)

[Claims] 1. A detection device for detecting the temperature and saturation pressure of a mixed refrigerant, which is used by mixing two types of non-azeotropic refrigerants, and two types of temperature detectors, which input the temperature and saturation pressure of the refrigerant from the detection device. A refrigerant mixing ratio detecting device for a refrigerator, comprising: an arithmetic device for calculating a mixing ratio of refrigerants. 2. The refrigerant mixing ratio detecting device according to claim 1, further comprising a correction circuit for inputting the mixing ratio of the mixed refrigerant from the detecting device to correct the set value of the safety device of the refrigerator. A refrigerator characterized in that.