JPH09170857A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To limit the air volume into the refrigerating cycle, in particular, the oxygen content to promote deterioration of the refrigerating cycle for the stable operation over the long time in a refrigeration air-conditioning system provided with a refrigeration compressor in which the refrigerant consisting of fluoro-carbon compound containing no chlorine and the refrigerator oil, a condenser, a refrigerant flow rate control part such as a capillary tube, and an evaporator. SOLUTION: In a refrigerating cycle to be constituted by connecting a unit 5 having a refrigeration compressor 1 and a heat exchanger 2 with the fluorocarbon compound containing no chlorine as the refrigerant to a unit 6 having a heat exchanger 2b installed at the part in which the refrigeration air-conditioning is performed, the residual oxygen content in the refrigerating cycle is limited to the range of >=1,500 vol.ppm and <=65,000 vol.ppm to the filling capacity of the refrigerator oil to be used for the compressor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system using a chlorine-free fluorocarbon compound as a refrigerant, and more particularly to a refrigeration cycle constructed by connecting an indoor unit and an outdoor unit using connecting pipes. Is.

[0002]

2. Description of the Related Art In a refrigerating cycle of a refrigerator, a refrigerator, an air conditioner, etc., RFC which is a chlorofluorocarbon (CFC) such as CFC containing fluorine and chlorine as a refrigerant.
11 (trichloromonofluoromethane), R12 (dichlorodifluoromethane), and hydrochlorofluorocarbon (HCFC) R22 (monochlorodifluoromethane) were used. Chlorine contained in the molecule has a preferable effect of preventing abrasion by reacting with the metal on the sliding surface in the refrigerator system, but this type of CFC compound is released when it is released into the atmosphere. , Most of them are not decomposed, they destroy the ozone layer in the stratosphere, and their use is being regulated internationally because they adversely affect biological systems. Therefore, studies have been made widely on alternative CFC substances that do not contain chlorine, and as a refrigerant for this type of refrigeration cycle, it is considered to use so-called alternative CFCs such as R134a instead of conventional CFCs. .

[0003]

However, when these new CFC alternatives are used as refrigerants for refrigeration systems, they are not compatible with mineral oils and alkylbenzene oils that have been conventionally used as refrigerating machine oils, and they are compressed. Such as deterioration of oil return to the machine and suction of separated refrigerant at startup,
There is a problem with the lubricity of the compressor.

Therefore, many proposals and studies have been made as an oil having a good compatibility with a refrigerant of a fluorine-containing carbon compound containing no chlorine. First, a polyoxyalkylene glycol (PAG) having hydroxyl groups at both ends was proposed as a lubricating oil for a refrigerator for R134a. PAG is R134
Although there is no problem in compatibility with a, it has become clear that it has high water absorption and it is difficult to maintain electrical insulation for a long period of time. Furthermore, fatty acid esters of polyhydric alcohols have been proposed as a group of compounds having good compatibility with R134a. This compound is superior in electrical insulation and has almost no hygroscopicity as compared with PAG. However, the system composed of this ester oil and a chlorine-free fluorocarbon compound refrigerant has a higher polarity than that of the conventional system composed of mineral oil and R12, and tends to contain water. As a matter of course, it is possible to attach a dryer for removing water to the refrigerator device, and it is possible to remove to a certain extent by this dryer. However, the hydrolysis of the ester proceeds due to the slightly remaining water, and a metal corrosive acid component is deposited. Further, these acids may react with the metal in the system to form metal soap, which may become sludge and precipitate in the piping, which may adversely affect the refrigeration cycle. Therefore, in order to use the ester oil as a refrigerating machine oil, it is necessary to develop a structure that does not easily hydrolyze.

As other oils compatible with R134a, various studies have been conducted on ether oils, carbonate oils, ketone oils, silicone oils and the like. Ether-based oils have good compatibility with alternative refrigerants such as R134a, but problems to be solved include two-layer separation in a high temperature region and electric insulation. Carbonate-based oils and ketone-based oils are likely to undergo decarbonation due to hydrolysis, heat, etc., and non-condensable gases that cause uncooling are likely to be generated. Fluorine-modified silicone oil is known as a silicone-based oil, but it is considered to have a large cost problem.

When these new CFC alternatives are used as refrigerants for refrigeration systems, it is necessary to select oils that are compatible with the refrigerants as described above, but in that case, compared with conventional mineral oils and the like. However, water absorption, water resistance, oxidation resistance, etc. are not sufficient, so it is necessary to limit the amount of air and water in the system. In addition, it is desirable for the oil itself to contain as little oxygen as possible, but considering the effects on lubricity and friction and wear characteristics, it should be mixed to some extent due to the extreme pressure exhibited by the oxide film. Is desirable.

On the other hand, considering the problem of the system configuration, in the refrigeration cycle constituted by connecting the indoor unit and the outdoor unit using the connection pipe, a large machine,
Construction is required regardless of the size of the machine. When forming a refrigeration cycle using connecting pipes in this way, oxygen remaining in the cycle must be removed in order to promote oxidative deterioration of refrigeration cycle substances such as refrigeration oil. For example, a method of removing it by using a refrigerant that has been filled in advance during the cycle is used. At present, there are clear air and moisture regulation standards,
There is no supporting data and it varies depending on the construction method, but in refrigeration equipment that uses a combination of new refrigerant and new refrigerating machine oil, new standards are needed to ensure stability in terms of material in the system. Is.

An object of the present invention is to provide a refrigerating machine equipped with a refrigerant flow rate control unit such as a refrigerating compressor, a condenser, a capillary tube, etc., which uses a refrigerant composed of a fluorine-containing carbon compound containing no chlorine and refrigerating machine oil as a working medium, and an evaporator. In an air conditioning system, in order to operate stably for a long period of time, the amount of air in the refrigeration cycle, particularly the amount of oxygen that promotes deterioration of the refrigeration cycle, is limited.

[0009]

DISCLOSURE OF THE INVENTION The present invention uses a fluorine-containing carbon compound containing no chlorine as a refrigerant, a compressor having a refrigeration unit, a unit having a heat exchanger, and a heat exchanger installed at a portion where refrigeration and air conditioning are performed. In a refrigeration cycle in which a unit having a unit is configured by using a connecting pipe, the amount of residual oxygen in the refrigeration cycle is within a range of 1,500 volppm or more and 65,000 volppm or less with respect to the filling capacity of the refrigerating machine oil used in the compressor. The refrigeration apparatus is characterized by being limited to.

Further, the refrigerating machine oil used in the compressor of the refrigerating cycle is an oil containing a polyol ester oil as a base oil.

Further, it is characterized in that the equilibrium water content (equation 2) in the refrigeration cycle is 50 wtppm or less in the steady state of operation.

(Amount of residual water in refrigeration cycle) / (amount of filled refrigerator oil + amount of filled refrigerant)-(2) Next, the principle and operation of the present invention will be described. In the first place,
Even when using a refrigerant composed of a fluorine-based carbon compound that does not contain chlorine and a refrigerating machine oil that is compatible with the refrigerant, the ambient environmental conditions for stable operation of the system are that the amount of oxygen in the system falls within a certain range. To be limited. Further, by limiting the amount of oxygen and the amount of water in the system, it is possible to provide a better working environment. That is, the main components of air are nitrogen, oxygen, water, carbon dioxide, etc. Among them, oxygen and water promote the oxidative deterioration or hydrolysis of the refrigerating machine oil during the refrigerating cycle, and therefore, during the construction of the refrigerating system. Must be excluded from the working medium flow path. However, in order to obtain smooth lubricity and friction and wear characteristics, it is effective that a very small amount of oxygen is mixed in from the viewpoint of extreme pressure.

First, regarding the relationship between oxygen and refrigerating machine oil, it is known that the refrigerating machine oil contains a considerable amount of dissolved oxygen. As a general value, in oil left in the air at room temperature, about 25,000-35,000 volp
pm oxygen is dissolved. As a result of various studies on dissolved oxygen in oil, we found that the dissolved oxygen value greatly changes depending on the depressurized state in the container in which the refrigerating machine oil is installed, the state of replacement with an inert gas, and It turned out to be manageable. As described above, in the management of the refrigerating apparatus in which the new refrigerant and the new refrigerating machine oil are combined, it is important to grasp and limit the amount of dissolved oxygen in the oil.

Furthermore, in order to examine the state of deterioration when refrigerating machine oil and oxygen coexist, we made various shield tubes with different internal pressures and conducted deterioration tests on them to obtain the following results. Got That is, when the pressure in the system is 50 Torr or less, there is not much difference in the deteriorated state, that is, the amount of metal soap produced in the acceleration test, even if the depressurized state is further increased. However, in the sample of 50 Torr or more, the amount of metal soap produced increases corresponding to the pressure in the system. I was able to clarify that. At this time, in order to make the influence of the dissolved oxygen in the oil the same condition as described above, the shield tube was evacuated for 30 minutes at an internal pressure of 5 × 10 ⁻⁵ Torr to make the dissolved oxygen sufficiently expelled in advance. Above, a predetermined amount of dry air was introduced into the system.

The results of those tests are shown in FIG. The horizontal axis represents a log plot of the internal pressure in the prepared shield tube, and the vertical axis represents the concentration of metal ions generated with respect to 1 g of deteriorated oil after the heating test.

At this time, 2 ml of oil was put in the tube, the empty capacity of the tube was 10 ml except for the oil part, and oxygen was 2
It means that it was mixed with ml. From this, the oxygen amount per 1 ml of oil is (oxygen amount in the tube) / (volume of oil in the tube) = (2 ml × 50/760) / (2 ml) when the pressure in the tube is 50 Torr = 65,800volppm concentration is calculated. In other words, 6 for the volume of oil
When the content is 5,000 volppm or less, the work can be performed efficiently and the oxidative deterioration of the oil can be minimized.

The lower limit value of oxygen is 1 for oil.
This is because if it is 500 volppm or less, the lubricity is adversely affected.

On the other hand, regarding water content other than air content that causes deterioration in the system, the equilibrium water content in the system is 50 pp.
By controlling to m or less, the rate of acid generation and iron salt generation by the hydrolysis reaction can be minimized, so that the effect can be further exerted on the long-term stability in the system. Here, the residual water content in the refrigeration cycle is defined as follows.

(Amount of residual water in refrigeration cycle) / (Amount of filled refrigerating machine oil + Amount of filled refrigerant)

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to embodiments.

First, a refrigeration system applied in the present invention will be described with reference to the drawings. FIG. 1 is a refrigeration system diagram applied in the present invention, in which a refrigeration compressor 1, a heat exchanger 2a,
An outdoor unit 5 having a refrigerant flow rate control unit 3 such as a capillary tube or an expansion valve and a pipe 4 connecting them.
And an indoor unit 6 having a heat exchanger 2b installed in a portion where refrigeration and air conditioning are performed, connecting pipe 7, service valve 8
a and 8b and flare nuts 9a and 9b are connected. In this case, since it has the four-way valve 10, the function of condensation or evaporation of the heat exchangers 2a and 2b can be exchanged. The accumulator 11 may be equipped.

As for the flow of the refrigerant, when the cooling operation is performed, the refrigerant compressed by the refrigerating compressor 1 radiates heat in the heat exchanger 2a, becomes a liquefied state, and passes through the refrigerant flow rate control section 3 so that the temperature becomes low. And becomes a dry saturated vapor in the heat exchanger 2b in the indoor unit 5, and is sucked into the refrigeration compressor again. When the flow path is switched by the rotation of the four-way valve 10, the heat is condensed in the heat exchanger 2b and evaporated in the heat exchanger 2a, and a heating operation is performed.

Next, an outdoor unit having a refrigerating compressor and a heat exchanger, and an indoor unit having a heat exchanger installed in a portion where refrigeration and air conditioning are performed are connected by a working medium flow passage pipe, and then a refrigeration cycle. A method of suppressing the amount of residual oxygen in the inside will be described.

As shown in FIG. 2, in the refrigerating and air-conditioning system in which the outdoor unit 5 and the indoor unit 6 are connected by the flow path pipe of the working medium, the outdoor unit 5 and the indoor unit 6 are connected to the connecting pipe 7 and the service valves 8a, 8b and. It is connected by flare nuts 9a and 9b. Valves 8a and 8b for controlling the connection between the outdoor unit side working medium flow path and the working medium flow path piping side
Has a port 12a, 12b with a check valve for exhausting with a vacuum pump and additional charging with a refrigerant, in addition to a joint port with the flow path pipe of the working medium. Port 12a
Is connected to a vacuum pump, and the residual oxygen in the refrigeration cycle is sucked until it reaches a certain range. Then port 12b
Then, the refrigerant is filled in the vacuum-treated pipe.

[0025]

EXAMPLES Next, more specific examples will be described.

(Embodiment 1) An outdoor unit having a refrigeration compressor, a heat exchanger, a capillary tube and an indoor unit having a heat exchanger installed at a portion where refrigeration and air conditioning are performed were fixed at respective installation positions. Next, a copper pipe was used as the refrigerant pipe between them. Connect these connecting pipes with the service valve and flare nut, and
A refrigeration system as shown in Figure 3 was constructed. The system unit capacity of the outdoor unit used here is 20 liters, and is pre-filled with nitrogen. Further, the compressor in the outdoor unit is filled with 1.5 liters of ester-based refrigerating machine oil. At this time, the ester-based refrigerating machine oil in the compressor is used so that the dissolved oxygen amount is 20 ml or less. Further, the indoor unit was filled with air, and the total capacity including the piping capacity of the portion excluding the outdoor unit was 30 liters.

Next, a vacuum pump was attached to the port provided on the service valve to remove the residual oxygen in the indoor unit and piping. After that, the service valve is also opened, the nitrogen filled in the outdoor unit is also removed, and the vacuum pump is used until the following conditions are satisfied.

Since the volume of the system used in this embodiment is 50 liters in total, it is necessary to reduce the internal pressure to 7.4 Torr or less. The calculation method is shown below.

The allowable oxygen amount for 1800 ml of oil is 1800 ml × 65,000 / 1,000,000.
= 117 ml, of which 20 ml exists as dissolved oxygen in the oil, 97 ml of oxygen obtained by subtracting that amount becomes the maximum allowable oxygen amount of the system, and since the total internal volume in the system is 50 liters, 97 ml / 50, 000ml x 760Torr = 1.4
7 Torr This becomes oxygen partial pressure, and the air becomes 1.47 Torr × 5 = 7.4 Torr. Therefore, it is a condition for ensuring reliability that the value is reduced to 7.4 Torr.

In this embodiment, the pressure was reduced to 5 Torr and then the refrigerant was charged. Then, the valve was closed and the vacuum pump and the refrigerant charging device were removed from the refrigerant flow path.

After continuous operation for 3000 hours, the refrigerating machine oil was taken out, but no oxidative deterioration of the refrigerating machine oil was observed, and the total acid value of the refrigerating machine oil was 0.02 mgKOH / g, the value at the start of operation (0.01 mgKOH / g) was almost the same value.

(Embodiment 2) An outdoor unit having a refrigerating compressor, a heat exchanger, a capillary tube and an indoor unit having a heat exchanger installed at a portion where refrigeration and air conditioning are performed were fixed at respective installation positions. Next, a copper pipe was used as the refrigerant pipe between them. These connection pipes were connected by a service valve and a flare nut, and a refrigeration system similar to that in Example 1 was constructed. The system unit capacity of the outdoor unit used here is 20 liters, and is pre-filled with nitrogen. Further, the compressor in the outdoor unit is filled with 1.5 liters of ester-based refrigerating machine oil. At this time, the ester-based refrigerating machine oil in the compressor is used so that the dissolved oxygen amount is 20 ml or less. Further, the indoor unit was filled with air, and the total capacity including the piping capacity of the portion excluding the outdoor unit was 30 liters.

Next, a vacuum pump was attached to the port provided on the service valve to remove residual oxygen in the indoor unit and the piping. After that, the service valve is also opened, the nitrogen filled in the outdoor unit is removed, and the pressure is reduced to 5 Torr.
After that, the refrigerant was filled. Then, the valve was closed and the vacuum pump and the refrigerant charging device were removed from the refrigerant flow path. The residual oxygen amount when the pressure in the system is 5 Torr is 5/760 × 50,000 l ÷ 5 = 65.
Since it contains 8 ml, for 1800 ml of oil, 65.8 / 1800 × 1,000,000 = 3
Equivalent to 6,600volppm.

Then, after 12 hours of operation, the operation was stopped once,
When the water content in the refrigerant was measured, it was 30 wtppm.

After continuous operation for 3000 hours, the refrigerating machine oil was taken out, but no oxidative deterioration of the refrigerating machine oil was observed, and the total oxidation number of the refrigerating machine oil was 0.01 mgKOH / g, which was the value at the start of operation (0.01 mgKOH / g ) Was the same value.

(Comparative Example) An outdoor unit having a refrigerating compressor, a heat exchanger, a capillary tube and an indoor unit having a heat exchanger installed at a portion to be refrigerated and air-conditioned were fixed at respective installation positions. Next, a copper pipe was used as the refrigerant pipe between them. These connecting pipes are connected by a service valve and a flare nut, and the first embodiment is used.
The same refrigeration system was constructed. The system unit capacity of the outdoor unit used here is 20 liters, and is pre-filled with nitrogen. Further, the compressor in the outdoor unit is filled with 1.5 liters of ester-based refrigerating machine oil. At this time, the ester-based refrigerating machine oil in the compressor is used so that the dissolved oxygen amount is 20 ml or less. The indoor unit is filled with air, and the total capacity including the piping capacity of the part excluding the outdoor unit is 3
It was 0 liter.

Next, a vacuum pump was attached to the port provided on the service valve to remove residual oxygen in the indoor unit and the piping. After that, the service valve is also opened and the nitrogen filled in the outdoor unit is removed, and the vacuum pump
It was pulled to Torr and then charged with a refrigerant. Then, the valve was closed and the vacuum pump and the refrigerant charging device were removed from the refrigerant flow path. When the pressure in the system is 50 Torr, the residual oxygen amount is 50/760 × 50,000 l ÷ 5 = 65 excluding the oxygen in the oil.
Since it contains 8 ml, for 1800 ml of oil, 658/1800 × 1,000,000 = 36
It corresponds to 6,000 volppm, which is outside the conditions of claim 1.

After continuous operation for 3000 hours, the refrigerating machine oil was taken out, but the refrigerating machine oil turned yellow and the deterioration of the refrigerating machine oil proceeded.

[0039]

As is apparent from the above description,
According to the present invention, in a refrigerating air-conditioning apparatus equipped with a refrigerating compressor that uses a refrigerant containing a chlorine-free fluorocarbon compound and refrigerating machine oil as a working medium, a condenser, an expansion valve or a capillary, and an evaporator, during a refrigerating cycle. By restricting the entry of air into the chamber, stable operation can be achieved over a long period of time.

[Brief description of the drawings]

FIG. 1 is a simplified diagram of a refrigeration system used in the present invention.

FIG. 2 is a diagram showing a vacuum pump and a refrigerant filling port of a refrigeration system used in the present invention.

FIG. 3 is a graph showing a relationship between a change in internal pressure by a shield tube test and a production amount of metal ions.

[Explanation of symbols]

 1 Refrigerating compressor 2 Heat exchanger 3 Refrigerant flow rate control unit 4 Piping 5 Outdoor unit 6 Indoor unit 7 Connection pipe 8 Service valve 9 Flare nut 10 Four-way valve 11 Accumulator 12 Port with check valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuya Wakita 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yusuke Ozaki, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Nobuo Sonoda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A connecting pipe for connecting a unit having a compressor for refrigeration and a heat exchanger, and a unit having a heat exchanger installed at a portion where refrigeration and air conditioning are performed, using a fluorine-based carbon compound containing no chlorine as a refrigerant. In the refrigeration cycle configured using, the residual oxygen amount in the refrigeration cycle is 1,500 volp with respect to the filling capacity of the refrigerating machine oil used in the compressor.
Refrigeration equipment characterized by being restricted to a range of pm or more and 65,000 volppm or less. 2. The refrigerating machine according to claim 1, wherein the refrigerating machine oil used in the compressor of the refrigerating cycle is an oil containing a polyol ester oil as a base oil. 3. Equilibrium water content in the refrigeration cycle (Equation 1)
Is the residual water content in the refrigeration cycle / (filled refrigerator oil amount + filled refrigerant amount)-(1) 50 wtppm or less in a steady operation state.