JP3241694B2 - Ammonia refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonia refrigeration system using a refrigerant containing ammonia as a main component and constituting a refrigeration cycle or a heat pump cycle.

[0002]

2. Description of the Related Art Conventionally, chlorofluorocarbon has been widely used as a refrigerant for refrigeration and heat pump devices (hereinafter referred to as refrigeration system). And its use has been limited because it destroys the ozone layer, which serves to protect the earth from the strong ultraviolet rays of the sun. Thus, in recent years, ammonia has been reviewed as an alternative refrigerant to CFCs.

[0003] That is, the ammonia refrigerant has no fear of destruction of the global environment unlike CFCs, and its refrigeration effect is not less than that of CFCs, and is also inexpensive. However, ammonia is toxic,
A refrigeration system configuration that is flammable, insoluble in mineral oil used as compressor lubricating oil, and has drawbacks such as high discharge temperature from the compressor. Has been taken.

[0004] Referring to FIG. 6, the specific structure of the evaporator is, for example, -10 ° C. on the evaporator side and +3 on the condenser side.
This is a single-stage compression type direct expansion refrigeration system for obtaining heat of about 5 ° C. The structure of the system will be described mainly. The oil-mixed ammonia refrigerant compressed by the refrigerant compressor 51 is supplied to an oil separator 52. After oil separation in the condenser 53, the oil is condensed and liquefied in the condenser 53 by heat exchange (acquisition heat: about 35 ° C.) with the cooling water 64 in the condenser 53. After the oil liquefied and separated at the time of the condensation is further separated by an oil reservoir 55 provided at the bottom of the high-pressure receiver 54, the ammonia refrigerant is decompressed and vaporized by an expansion valve 56, and the air supplied from a fan 58 in an evaporator 57. After heat exchange with the load (acquisition heat: −10 ° C.), the refrigerant is further sucked into the suction side of the compressor 51 via the ammonia liquid / oil separator 59 and the refrigeration cycle is repeated.

The oil collected at the bottom of the oil separator 52, the oil reservoir 55 at the bottom of the liquid receiver, and the bottom of the evaporator 57 are all transferred to the oil receiver 61 via oil drain valves 60a, 60b, 60c, and 60d. The oil is collected and returned to the inside of the compressor 52 again from the oil injection portion 52a of the compressor 51, and performs lubrication, sealing, cooling, and the like of the movable portion. It is well known that the refrigerating device 50 can be applied as a heat pump device by extracting heat from the condenser 53 side. Therefore, these are collectively referred to as a refrigerating device.

[0006] The lubricating oils are generally paraffinic,
Mineral lubricating oils such as naphthenic oils are used, but since these lubricating oils do not dissolve with ammonia, an oil separator is provided on the discharge side of the compressor, and the lubricating oil and lubricating oil are separated from the ammonia gas discharged from the compressor. Separates oil, and even if the separator is provided, mist-like lubricating oil cannot be completely removed, or
Since the discharge side of the compressor is hot, lubricating oil is slightly dissolved or mist is mixed in the ammonia, enters the refrigeration cycle with the ammonia, and the lubricating oil that has entered the cycle is Since it is insoluble in ammonia and has a high specific gravity, it easily accumulates in the piping path of the cycle. Therefore, the oil draining portions 55 and 60 are provided at the bottom of the high-pressure receiver 54 and the lower inlet side of the evaporator 57, respectively. Also, an oil separator 59 must be provided on the suction side of the compressor 51, and after these separated oils are collected by the oil receiver 61,
It is necessary to return to the compressor side again, and the configuration becomes extremely complicated.

Further, the fact that the lubricating oil is insoluble in the refrigerant as described above means that the oil adheres to the heat exchange coil wall surfaces in the condenser 53 and the evaporator 57 and the heat transfer efficiency is reduced. In particular, in a low-temperature evaporator, the viscosity of the oil is increased, the fluidity of draining oil is reduced, and the heat transfer efficiency is further reduced. For this reason, it is necessary to separate the insoluble oil as much as possible on the inlet side of the evaporator 57. In order to introduce the decompressed refrigerant after passing through the expansion valve 56 from above the evaporator 57,
Even if a special separator is used, it cannot be prevented from entering the evaporator 57 due to a difference in specific gravity. Therefore, in the system having the above-mentioned structure, a so-called bottom feed structure in which an introduction portion is provided on the bottom side of the evaporator 57 is provided. I have to take it.

However, if the bottom feed structure is adopted, it is inevitable to take a so-called full structure in which the refrigerant can be discharged from the upper end of the evaporator against the gravity corresponding to the height of the evaporator 57. Requires many refrigerants in the refrigeration cycle.

Although the above-mentioned ammonia refrigeration system has a service limit of about -20 ° C., the temperature of industrial processes has been remarkably reduced in recent years, and especially in the food industry, prevention of melting of fat at the time of thawing and other quality maintenance. In most cases, the required freezing temperature is from −30 ° C. to the following, and especially in the case of high-priced food such as tuna, the frozen storage temperature is −50 ° C. to −60
℃ and significantly lower. Such a freezing temperature cannot be obtained with the single-stage compressor as described above.
Although a stage compressor is used, when the temperature of the evaporator is cooled to −40 ° C. or lower as in the conventional technology, as shown in Table 3 below, the fluidity of the lubricating oil is significantly reduced, Clogging and the like easily occur in the vessel.

In order to solve such a drawback, a cryogenic ammonia two-stage compression type liquid pump recirculation system as shown in FIG. 7 has been proposed. The configuration will be briefly described with a focus on the difference from the prior art. The condensate discharged from the high-pressure receiver 54 into the liquid pipe 66 cools the inside of the intermediate cooler 68 by the expansion valve 67, while the liquid pipe The terminal side of 66 is an intercooler 6
After being introduced into a supercooling pipe 69 inside the supercooling pipe 8 and cooled to about −10 ° C. in the supercooling pipe 69, it is vaporized under reduced pressure by an expansion valve 74 and introduced into a low-pressure receiver 70.

As a result, in the liquid receiver 70, -40 to 40 is provided.
The refrigerant liquid cooled to −50 ° C. or lower is stored. Then, the refrigerant liquid is supplied to the liquid pump 71 and the flow control valve 7.
2 through the evaporator 73, and exchanges heat with the blowing load supplied from the fan 74 in the evaporator 73 (example of acquired heat: −
The refrigerant evaporated at (40 ° C.) is again introduced into the low-pressure receiver 70 to be cooled and condensed and liquefied.

On the other hand, the vaporized refrigerant in the low-pressure receiver 70 is
The compressed gas is sucked and compressed by the low-stage compressor 75, and the compressed gas is cooled in the intercooler 68, introduced into the supercooling pipe 69 for heat exchange in the intercooler 68, and condensed from the liquid pipe 66. The refrigerant is supercooled to about −10 ° C., decompressed and vaporized by the expansion valve 74, and introduced into the low-pressure receiver 70. Then, the vaporized refrigerant in the intercooler 68 is compressed by the high-stage compressor 51 ', and the cycle is repeated. Oil reservoirs 55, 68a, 70a are provided at the bottom of any of the high-pressure receiver 54, the intercooler 68, and the low-pressure receiver 70, and these separated oils are collected by the oil receiver 61 and then again. Compressor 51 ',
Return to the 75 side oil injection units 51a, 75a. In the figure, 76
Is a liquid level float valve.

However, even in the prior art,
Not only basic drawbacks such as complicated oil recovery configuration and reduced heat transfer efficiency are not solved, but also the low pressure receiver 70
On the side, since the coolant liquid cooled to -40 to -50 ° C is stored, the lubricating oil stored in the oil reservoir is also cooled to around -40 to -50 ° C, and the fluidity is reduced. The temperature of the oil must be temporarily increased in order to greatly reduce the oil drainage.As a result, continuous operation of the refrigeration cycle is hindered, and the cycle is stopped every time a predetermined amount of the oil is stored. Maintenance is required to recover the oil.

On the other hand, hermetic compressors are often used in home refrigerators and air conditioners, and CFCs and HCFC refrigerants such as dichlorodifluoromethane (R12) and chlorodifluoromethane (R22) have been used in the past. HFCs that do not contain chlorine, such as 1,1,1,2-tetrafluorocarbon (R134a), are to be used, but such chlorofluorocarbon gas is expensive, while ammonia is more expensive than chlorofluorocarbon. Inexpensive, good heat transfer coefficient, high allowable temperature (critical temperature) and pressure as refrigerant,
The use of ammonia is advantageous because it dissolves in water, so there is no clogging of the expansion valve, the latent heat of evaporation is large and the refrigeration effect is large, but the hermetic compressor has a structure in which the motor and compressor are integrally sealed. Therefore, it is impossible to use ammonia itself because it has corrosion property to copper-based materials, and it is extremely difficult to recover and circulate oil only because ammonia and lubricating oil are non-melting. Cannot be used.

[0015]

However, if a lubricating oil having excellent solubility with ammonia and not deteriorating in quality even after long-term use has been developed, most of the above problems can be solved. You. Lubricating oils having such compatibility have already been proposed in the field of chlorofluorocarbons, and for example, esters of polyhydric alcohols and polyoxyalkylene glycol-based compounds are known, but there is no example for ammonia refrigerant. . Ammonia has a strong reactivity, so if the ester is slightly hydrolyzed, it will form an acid amide and cause sludge precipitation, and poor solubility with ammonia. It is difficult to use in combination.

In view of the above technical problems, the present invention provides a working fluid composition for a refrigerator, which is obtained by mixing a lubricating oil having excellent compatibility with an ammonia refrigerant and excellent lubricity and stability and an ammonia refrigerant. An object of the present invention is to provide a refrigeration apparatus suitable for using a product (hereinafter simply referred to as a working fluid composition). Another object of the present invention is to provide a refrigeration apparatus which can go one step further to solve the above-mentioned disadvantages of ammonia.

[0017]

According to the present invention, a refrigerant compressor, a condenser, an expansion valve and an evaporator are provided.
Refrigeration or heat pump
In the ammonia refrigeration system constitutes a cycle, the cold
Ammonia refrigerant and lubricating oil in it during the freezing cycle
A base fluid of the lubricating oil, comprising a working fluid composition
Is the terminal OH group of the polyoxyalkylene glycol.
At least a part of the hydrogen is converted into a hydrocarbon group having 1 to 6 carbon atoms.
One or more polyethers thus blocked
Ammonia which is a compound and is in the refrigeration cycle
The weight ratio of the refrigerant to the lubricating oil is from 70:30
By setting 97: 3, during the refrigeration cycle,
Ammonia refrigerant and the lubricating oil in it
Do not separate two layers even at the near refrigerant evaporation temperature
Characterized in that the configuration was.

Further, according to the present invention, the working fluid composition in which the ammonia refrigerant and the lubricating oil which have been condensed in the condenser is dissolved can be expanded without separating the refrigerant and the lubricating oil.
And into the intercooler, more preferably,
The working fluid composition in which the ammonia refrigerant and the lubricating oil have been dissolved after passing through the expansion valve or the intercooler can be introduced by a top feed toward an outlet provided on a bottom side from an inlet provided on an upper end side of an evaporator. It is good to configure.

Further, the working fluid composition in which the ammonia refrigerant and the lubricating oil are dissolved, which is derived from the evaporator, has the same heat as the working fluid composition condensed in the condenser. After the heat exchange, the heat exchanger may be configured to be introduced into the compressor. In this case, the average particle size is 150 ° or less,
Preferably, ultrafine diamond of 50 ° or less is added to the lubricating oil.

According to a seventh aspect of the present invention, the compressor side of the ammonia refrigerating apparatus according to the first aspect is specified, and a sealed ammonia compressor is directly connected to a pressure-resistant sealed motor including a stator and a rotor. On the inner peripheral surface side of the stator core, which is located around the rotor on the side of the electric motor, surrounds the rotor with a predetermined gap via a confidentiality seal portion, and further includes the rotor space. And a compressor between the compressor and the compressor.

[0021] The invention according to claim 8 also provides the above-mentioned claim 1.
The compressor side of the ammonia refrigeration apparatus described is specified, it is configured by directly connecting a sealed ammonia compressor and an electric motor, and the stator core located around the rotor on the electric motor side as a pressure-resistant sealed structure container. In addition, a seal member is provided on the front side of the fixed iron core facing the rotor of the groove after insertion of the winding, and the inside of the groove can be hermetically sealed via the seal member. It is characterized by the following.

As described above, the base oil of the lubricating oil used in the present invention is a polyoxyalkylene glycol having a terminal O-terminal.
At least a part of hydrogen of the H group is one or more polyether compounds which are blocked by a hydrocarbon group having 1 to 6 carbon atoms. In this case, the ammonia refrigerant and the lubricating oil may be mixed in advance to form a working fluid composition, or each may be separately charged in a refrigeration or heat pump cycle to constitute a working fluid composition in the cycle. Is also good.

That is, an ether compound in which a terminal OH group of a polyoxyalkylene glycol having a specific structure is substituted with an OR group (hereinafter, simply referred to as a polyether) is excellent in compatibility with ammonia, and even in the presence of ammonia. They have been found to exhibit excellent lubricity and stability.

Examples of such an ether compound include a working fluid composition comprising a mixture of ammonia and a lubricating oil for an ammonia compressor using a compound of the following chemical formula (I) as a base oil of a lubricating oil. R ₁ -[-O- (PO) _m- (EO) _n -R ₂ ] _x (I) (In the general formula (I), R ₁ is a hydrocarbon group having ₁ to 6 carbon atoms, and R ₂ is a carbon group having ₁ to 6 carbon atoms. 1-6 alkyl groups, PO
Is an oxypropylene group, EO is an oxyethylene group, x is an integer of 1-4, m is a positive integer, and n is 0 or a positive integer. In addition, the lubricating oil of the present invention is not limited to the first invention, and may be any lubricating oil that can be easily dissolved in an ammonia refrigerant and does not separate into two layers even at the evaporation temperature of the refrigerant.

Further, the lubricating oil containing the compound of the formula (I) as a base oil is not necessarily used only as a working fluid compatible with ammonia, but may be used alone as a lubricating oil for an ammonia compressor. The compound represented by formula (I) will be described in detail. The compound of the formula (I) is collectively referred to as a so-called polyoxyalkylene glycol compound, which is referred to as HCFC or CFC.
Many examples of using as a lubricating oil for refrigerators using FC as a refrigerant are known. For example, U.S. Pat. No. 4,948,525 (corresponding Japanese Application: Publication Nos. 2-43290 and 2-84491) discloses a polyoxyalkylene glycol monoether having a structure of the general formula R _1- (OR ₂ ) a-OH (R ₁ has _{1 to 1} carbon atoms).
18 alkyl group, R ₂ is a C1-C4 alkylene group), US Pat. No. 4,267,064 (corresponding Japanese application: Publication 6)
1-52880) and US Pat. No. 4,248,726 (corresponding Japanese application: Publication No. 57-42119) include R _1- [O- (R ₂
O) m-R _3] n or _{R 1 -O- (R 2 O)} m-R 3 polyglycolic structure (R _1, R ₃ is hydrogen, a hydrocarbon group, ant -
US Pat. No. 4,755,316 (corresponding Japanese Patent Application Publication No. 2-502385) discloses a polyalkylene glycol having at least two hydroxyl groups in US Pat.
(Corresponding Japanese application: JP-A-2-276890) discloses a combination of a polyether polyol and an ester in US Pat.
1712 (corresponding Japanese application: Publication 3-10497)
Discloses a polyoxyalkylene glycol having one hydroxyl group by copolymerizing EO and PO. It is described that each of these is excellent in solubility with HFC and HCFC.

On the other hand, as lubricating oil for a compressor for HFC, R
_{1 -O- (AO) n-H} , polyoxyalkylene glycol monoether of R ₁ -O- (AO) _n of -R ₂ structure, patents on polyoxyalkylene glycol ethers, Japan Publication 1-259093, the 1-25909
4, 1-25995 and 3-109492.

However, none of these known documents describes the relationship with ammonia. HF
C and HCFC are inert, while ammonia has a high reactivity and a completely different solubility. Therefore, such information is not useful for completing the present invention used in the coexistence with an ammonia refrigerant.

As for ammonia refrigerant, "Synthet
ic Lubricant and Their Refrigeration Application
s ", Lubrication Engineering, Vol. 46, No. 4, Page 239-
249, it is stated that poly-α-olefins having a high viscosity index and isoparaffinic mineral oil are useful as lubricating oils for ammonia refrigerants, and esters form sludge and solidify after long-term use. Publication No. 58-106370) describes an improvement of an ammonia refrigerant refrigeration system. However, none of these known documents describes the relationship between the ammonia refrigerant and the polyether compound.

The polyether of the general formula (I) has a viscosity required as a lubricating oil, and depends on the application.
Have a viscosity of 22-68 cSt and a viscosity of 5-15 cSt at 100C. A factor that greatly affects the viscosity is the molecular weight.
00-1800 is preferred.

The polyether of the general formula (I) is a polyether in which all terminals are blocked by R ₁ and R ₂ . Here, R ₁ is a hydrocarbon group having ₁ to 6 carbon atoms. Here, the hydrocarbon group means the following (i) or (ii). That is, R ₁ is (i) a saturated linear or branched C1-C6 chain hydrocarbon group, specifically a C1-C6 alkyl group derived from a C1-C6 aliphatic monovalent alcohol; That is, it is any of a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, an isopentyl group, a hexyl group, and an isohexyl group. An alkyl group having 1-4, more preferably an alkyl group having 1-2 carbon atoms, that is, a methyl or ethyl group, or (ii) a divalent saturated aliphatic polyhydric alcohol having 2-4 valences, specifically, ethylene glycol, propylene Glycol, diethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol , Neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, hydrocarbon residues derived from pentaerythritol, that is, all of the 2-4 hydroxyl groups of these 2-4 alcohols are all It means a substituted hydrocarbon group. Therefore, x in the general formula (I) is an integer of 1 to 4 corresponding to the valence of the alcohol to be a group of the hydrocarbon group of R ₁ . For particularly high solubility with ammonia, x is 1 and R ₁
Is preferably a methyl or ethyl group.

R ₂ is an alkyl group having 1 to 6 carbon atoms. With an alkyl group of 7 or more, the two-layer separation temperature with ammonia increases. R ₂ has 1-4 carbon atoms, furthermore, 1-
In the case of 2, the compatibility with ammonia, that is, the two-layer separation temperature is further reduced, so that it is preferable. When x is 2-4, R
₂ has 2 to 4 alkyl groups, which may be the same or different, and maintaining good compatibility is that R ₂ has 1-4, especially 1-2 preferable. Generally, as the number of carbon atoms of R ₁ and R ₂ increases, the temperature of the two-layer separation with ammonia tends to increase. Therefore, in order to maintain good compatibility, the total number of carbon atoms of R ₁ and R ₂ must be 1
0 or less, more preferably 6 or less, still more preferably 4 or less,
Most preferably, it is 2. When one or both of R _{1 and} R ₂ are hydrogen, sludge is generated by the reaction with ammonia.

In synthesizing the compound of the general formula (I), 1
If the hydroxyl groups of the -4 valent alcohol remain unreacted at least partially, the resulting polyol is not preferred because sludge is formed during long-term use. Therefore, the hydroxyl group of the alcohol should not remain as much as possible. Specifically, the hydroxyl value of the compound of the general formula (I) is 1
It is preferably 0 mgKOH / g or less, more preferably 5 mgKOH / g or less.

As described above, the viscosity of a lubricating oil based on the polyether compound represented by the general formula (I) is 40 ° C.
22-68 cSt at 100C and 5-16 cSt at 100C. This viscosity is necessary for maintaining good lubricity in the presence of ammonia. In order to maintain good solubility with ammonia, the average molecular weight is preferably from 300 to 1800. If the average molecular weight is less than 300, the viscosity becomes low and good lubricity cannot be obtained. If it exceeds 800, the compatibility with ammonia deteriorates. The control of the average molecular weight can be achieved by appropriately selecting the degrees of polymerization m and n in addition to R ₁ and R ₂ .

Further, the relative ratio of the degree of polymerization (m) of the oxypropylene group and the degree of polymerization (n) of the oxyethylene group, ie, the value of m / (m + n), determines the lubricity, low-temperature fluidity, and compatibility with ammonia. Is important. That is, if n is too large with respect to m, the low-temperature pour point increases or the compatibility with ammonia decreases. From this viewpoint, the value of m / (m + n) is preferably 0.5 or more. The compound of the general formula (I) in which n is 0 has good compatibility with ammonia and good lubricity. However, oxypropylene (P
O) is a copolymer of oxypropylene (PO) and oxyethylene (EO) rather than a homopolymer of
The polyether having (m + n) of 0.5 or more has improved lubricity while maintaining good compatibility. On the other hand, oxyethylene alone or a polyether obtained by polymerizing oxyethylene in a larger amount than oxypropylene has a high pour point and a high hygroscopicity, and thus requires attention. From the viewpoint of compatibility with ammonia, lubricity and fluidity, m /
The preferred range of the value of (m + n) is 0.5 to 1.0, more preferably 0.5 to 0.9, and still more preferably 0.7-1.0.
0.9.

The copolymer of oxyethylene and oxypropylene is represented by a block copolymer for convenience in the general formula (I), but is not limited to a block copolymer but may be a random copolymer. An alternating copolymer may be used. In the block copolymerization, the bonding order of the oxyethylene portion and the oxypropylene portion may be any _one , that is, R ₁ and either may be bonded. A polyether compound obtained by polymerizing oxyalkylene having 4 or more carbon atoms, such as oxybutylene, is not preferable because it is not compatible with ammonia.

Next, the compatibility with the ammonia refrigerant, ie, 2
The setting of the layer separation temperature is determined based on the application used. For example, a cryogenic refrigerator has a two-layer separation temperature of -50.
Lubricating oil below ℃ is required, and -30
C. or less is sufficient, and lubricating oil of -20.degree. C. or less is sufficient for an air conditioner. Particularly when a compound having a low two-layer separation temperature is required, R ₁ is most preferably a methyl group.

The compounds of the general formula (I) can be used alone or in combination of two or more. For example, polyoxypropylene dimethyl ether having a molecular weight of 800 to 1000 and polyoxyethylene propylene diethyl ether having a molecular weight of 1200 to 1300 are used alone or in a mixture of 10:90 to 90:10 (weight), and have a viscosity of 40 to 50 cSt at 40 ° C. Is exemplified.

The polyether compound of the general formula (I) is obtained by polymerizing an alkylene oxide having 2 to 3 carbon atoms by using a 1 to 4 alcohol having 1 to 6 carbon atoms or an alkali metal salt thereof as a starting material. Can be obtained by obtaining an ether compound in which one end of the polyalkylene group is bonded to the hydrocarbon group of the raw material alcohol by an ether bond, and the other end is a hydroxyl group, and then etherifying the hydroxyl group. To etherify the hydroxyl group of the ether compound having a hydroxyl group at the terminal, an alkali metal such as sodium metal or an alkali metal salt of a lower alcohol such as sodium methylate is reacted to obtain an alkali metal salt of the ether compound. The alkali metal salt has 1 carbon atom
A method of reacting an alkyl halide of -6 or a method of converting a hydroxyl group of an ether compound into a halide and then reacting with a monohydric alcohol having 1 to 6 carbon atoms is used.

Therefore, it is also possible to use a polyoxyalkylene glycol having hydroxyl groups at both ends as a starting material without necessarily using an alcohol as a starting material. In any case, the polyether compound of the general formula (I) may be produced by an appropriate known method.

Therefore, the refrigerating machine oil is stably dissolved with ammonia in an extremely wide mixing ratio. In addition, good lubricity is exhibited in the presence of ammonia. Further, as will be described later, by adding an additive such as diamond clusters, the mixing ratio of the lubricating oil can be further reduced while the lubricity is secured. Therefore, the lubricating oil for refrigerators of the present invention uses the compound represented by the general formula (I) as a base oil, and the working fluid composition circulating in the refrigeration and heat pump cycle of the present invention contains ammonia and The mixing ratio of the polyether compound of the formula (I) is preferably 98: 2 (weight ratio) or more.

The lubricating oil and working fluid composition for refrigerators of the present invention may contain various additives such as load-bearing agents such as tricresyl phosphate, amine-based antioxidants, and benzotriazole-based metal deactivators. An agent, an antifoaming agent for silicones, etc. can be added as necessary, but one that does not form a solid by reaction with ammonia should be selected. Therefore, phenolic antioxidants cannot be used. In addition, lubricating oils that may react with ammonia, such as polyol esters, should not be mixed, and mineral oil-based lubricating oils that do not dissolve in ammonia should not be mixed.

Next, the present invention using the working fluid composition will be described in detail. The present invention relates to an ammonia refrigerant,
It can be dissolved in the ammonia refrigerant and has an evaporation temperature of 2
A refrigeration system is filled with lubricating oil that does not undergo layer separation, and the filling ratio of the two is at least 2% by weight of lubricating oil in an ammonia refrigerant to constitute a refrigeration or heat pump cycle. The ratio between ammonia and lubricating oil varies depending on the type of compressor, but it is basically preferable to reduce lubricating oil as much as possible in order to increase heat transfer efficiency as long as lubricating performance is maintained. For example, in the refrigeration apparatus of the present invention using a rotary compressor, generally, the filling weight mixing ratio of ammonia refrigerant and lubricating oil,
Even if it is set to about 70 to 97: 30 to 3, sufficient lubricity and refrigerating ability can be obtained, which leads to a significant improvement in performance as described later.

That is, if 3% or more of the lubricating oil is dissolved,
The dissolution of the oil easily enters the sliding portion of the compressor, the galling is reduced, and the refrigeration cycle configuration is extremely simplified. Also, the lubricating oil constituting the working fluid composition has at least an average particle size of 150 ° or less, preferably an average particle size of about 50 °.
Å By adding the following ultrafine diamond or ultrafine diamond coated with graphite,
Even if the mixing ratio of the lubricating oil is reduced to about 2%, no problem occurs.

Such a diamond is, for example, described in (NEW DAIAMOND 1991 VOL8 No. 1, Characteristics of ultrafine diamond powder by a new explosion method and its application).
As described in the above, a cluster diamond obtained by purifying ultrafine diamond synthesized by detonating an explosive substance in an explosion chamber filled with an inert gas or graphite coated on the cluster diamond. It is preferable to use a carbon cluster diamond which is present, and by adding 2 to 3% by weight to the lubricating oil, it is possible to reduce the blending ratio of the lubricating oil in the working fluid to 2% by weight. .

Since the lubricating oil does not separate into two layers even at the evaporation temperature of the refrigerant and has excellent low-temperature fluidity, the separated oil adheres to the heat exchange coil not only on the condenser side but also on the evaporator side. Without fear, this not only greatly improves the heat transfer efficiency, but also eliminates the need to provide the oil recovery mechanism and the oil separator in the refrigeration cycle, thereby greatly simplifying the circuit configuration.

Further, in the compressor, the lubricating oil enters the sliding portion while being dissolved in the refrigerant, which helps to further prevent galling. In this case, the working fluid composition obtained by mixing the ammonia refrigerant and the lubricating oil after being compressed by the compressor may be configured to circulate through a refrigeration and heat pump cycle without interposing an oil recovery unit. In this case, even when the filling ratio of the lubricating oil is 10% by weight or more, a certain amount of the lubricating oil is stored in the compressor. The blending ratio of the oil can be set to 7% or less, and more favorable heat transfer efficiency can be obtained.

Further, a part of the lubricating oil in the working fluid composition after compression by the compressor may be returned to the compressor side. In particular, in the latter case, it is easy to increase the mixing ratio of the lubricating oil on the compressor side, and to minimize the mixing ratio of the lubricating oil introduced into the circulation cycle, particularly the evaporator side. Of course, the present invention is also applicable to a single-stage compression type refrigeration system.
It is also applicable to a stage compression type refrigeration system.

Further, since the composition has excellent lubricity and compatibility even at a temperature lower than the evaporation temperature of the refrigerant, a top feed structure for introducing the composition after passing through an expansion valve or an intercooler from above the evaporator. Therefore, it is not necessary to take a so-called full structure, and it is possible to reduce the cycle circulation amount of the refrigerant (composition) and obtain a high refrigeration effect. Further, the composition is compatible with the lubricating oil even at a temperature equal to or lower than the evaporation temperature of the refrigerant, but may be separated under severe conditions such as low-temperature vaporization in the evaporator. If so, the separated oil is introduced directly into the compressor, causing knocking and other problems.

Therefore, in the middle of the introduction line connecting the compressors from the evaporator, an oil sump for temporarily storing the separated oil and lubricating oil in the oil sump are introduced into the line, for example, as in a double riser. And a remixing unit for remixing with the working fluid composition introduced into the compressor.

By adopting the above configuration, the problem with respect to the insolubility of ammonia and the refrigerant has been solved. However, the problem of the strong corrosiveness and conductivity of ammonia, especially the corrosion resistance to copper materials, has not been solved, and unless it is solved, it is difficult to apply it to hermetic compressors, especially household refrigerators. is there. Therefore, the present invention relates to an ammonia refrigeration system using a sealed ammonia compressor in which an electric motor is directly connected to an ammonia refrigerant compressor, wherein an airtight seal is provided on an inner peripheral surface side of a stator core located around a rotor on the electric motor side. The present invention proposes a technology in which the rotor is surrounded by a predetermined gap with the rotor via a seal portion, and a conduction portion through which the composition can be conducted is provided between the inner space of the rotor and the compressor.

According to this invention, since the stator side on which the windings are mounted is isolated from the rotor housing space into which the ammonia refrigerant or the like flows by the airtight seal portion, the windings and the like may be damaged. The lubricating oil-containing composition flows into the rotor housing space, so that there is no risk of hindering the lubrication of the bearings such as the rotating shaft of the rotor, and the fluid composition in both spaces is eliminated. It is possible to equalize the pressure.
In this case, the hermetic seal portion may be constituted by a cylindrical can surrounding the rotor, but if a can is used, the alternating magnetic flux generated by exciting the stator wire loop forms a rotating magnetic flux. The stator is rotated by passing through the can of the gap, and an eddy current flows through the can, causing eddy current loss, which accounts for about half of the motor loss, heats the motor, and reduces efficiency.

Therefore, the stator core is constituted as a pressure-resistant sealed structure container, and an insulating thin film is interposed on the inner peripheral side of the stator core, or the stator core faces the rotor of the groove after insertion of the winding. A seal member may be provided on the front side to be sealed so that the inside of the groove can be hermetically sealed via the seal member. As a result, the above-mentioned disadvantages of the can can be eliminated, and since the stator core itself functions as a pressure-resistant container, the can becomes unnecessary, and the stator core is formed of a thick field core. In addition, sufficient pressure resistance can be obtained. The composition is configured to be leakable from the transmission shaft transmitting the rotation of the rotor to the compressor side, thereby facilitating lubrication and the like on the motor side, and the configuration is easy due to an incomplete seal. is there.

[0053]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention, but are merely illustrative examples, unless otherwise specified. Absent.

First, as lubricating oils, polyether compounds shown in Table 1 (Examples 1 to 8), naphthenic mineral oil-based refrigerating machine oils shown in Table 2 (Comparative Example 1), branched-chain alkylbenzenes (Comparative Example 2) and (Poly) ether compound (Comparative Example 3
8), the compatibility with ammonia, the Falex baking load, and the change in the hue, total acid value and appearance of the sample before and after the cylinder test in an ammonia atmosphere were evaluated. The physical properties of the naphthenic mineral oil-based refrigerating machine oil of Comparative Example 1 in Table 2 and the branched alkylbenzene of Comparative Example 2 are as follows. Naphthene mineral oil Branched-chain type refrigerating machine oil Alkylbenzene Density 0.888 0.870 Kinematic viscosity cSt (100 ℃) 4.96 4.35 Flash point ℃ 180 178

The outline of various test methods used for evaluating the composition of the present invention is as follows. Average molecular weight: The weight average molecular weight was measured by GPC (gel permeation chromatography). Kinematic viscosity: Measured according to JISK2283. Compatibility with ammonia: After sealing 5 g of sample oil and 1 g of ammonia in a glass tube, cooling was performed at a rate of 1 ° C./min from room temperature, and the temperature at which two layers were separated was measured. Falex baking load: ASTM D-3233-73
The Falex baking load was measured in accordance with. Bomb test: 50 g of sample oil was placed in a 300 ml bomb loaded with 3 m of iron wire having a diameter of 1.6 mm as a catalyst, pressurized to 0.6 kg / cm ² G with ammonia, and further increased to 5.7 kg / cm ² G with nitrogen gas. Pressurized. Then 1
Heated to 50 ° C. and held at that temperature for 7 days. After cooling to room temperature, ammonia was removed from the sample oil under reduced pressure,
Hue and total acid value before and after the test were measured, and changes in appearance were visually observed to evaluate the stability of the sample in an ammonia atmosphere. The appearance was evaluated according to the following criteria. No change: No change in appearance before and after the test Solidification: Sample solidified after test

The results of the test are shown in Tables 1 and 2.

[0057]

[Table 1]

[0058]

[Table 2]

From Tables 1 and 2, it can be seen that the polyether compounds of Examples 1 to 8 are excellent in compatibility with ammonia, lubricity, and stability in an ammonia atmosphere. A mixture of such a polyether compound and ammonia is filled and used in an ammonia compressor to exhibit its function sufficiently. As a result, the ammonia compressor can be made compact and maintenance-free, and has a special effect such as expanding the use of the ammonia compressor.

However, the naphthenic mineral oil-based refrigerating machine oils shown in Table 2, the branched-chain alkylbenzenes and Comparative Examples 3 to 8
It can be seen that each of the (poly) ethers is insoluble at room temperature or individualized by a bomb test even if it has compatibility at a low temperature of -50 ° C. As a result, these oils cannot be used in a refrigerating cycle in which compression / condensation / expansion is repeated.

Next, a refrigeration system using a working fluid composition obtained by mixing such a lubricating oil and an ammonia refrigerant will be described. FIG. 1 shows a single-stage compression type direct expansion refrigeration apparatus according to an embodiment of the present invention, in which R-717 (ammonia refrigerant) is used as a refrigerant and the polyether of the first embodiment is used as a lubricating oil. An example is shown in which a refrigeration cycle is filled in parts by weight. In the figure, reference numeral 11 denotes a refrigerant compressor. The refrigerant working fluid formed by dissolving the ammonia refrigerant and the lubricating oil compressed by the compressor 11 is directly guided to the condenser 12 without passing through the oil separator, and It is condensed and liquefied by heat exchange (acquisition heat: about 30 ° C.) with cooling water (cooling water pipe 18) in the vessel 12.

Then, the condensed working fluid is supplied to the high-pressure receiver 1
After being accumulated in the evaporator 15, it is decompressed and vaporized by the expansion valve 13, introduced into the evaporator 15 by a top feed through an inlet 15 a provided at the upper end of the evaporator 15, and exchanges heat with the blowing load supplied from the fan 16. (Acquisition heat: around -15 to -20 ° C)
After that, the refrigerant is sucked into the intake side of the compressor 11 via the double riser 17 and the refrigeration cycle is repeated. Here, as known, the double riser 17 is a main line 171 provided with a U-shaped local oil reservoir 172 provided on the outlet side of the evaporator 15 outlet portion 15b, and a bypass line for bypassing the main line. 173, the oil slightly separated by evaporation in the evaporator 15 is guided to the low-pressure suction pipe 19 side through the main line 171 while the oil is stored in the oil sump 172.
When the main line 171 is closed by an oil sump by making the bypass line 173 a narrow tube to give restriction resistance, the oil blocked by the flow rate of the vaporized refrigerant containing the lubricating oil passing through the bypass line 173 is removed by the low-pressure suction pipe 19. It is guided to the suction side of the compressor 11 in a state where it is drawn out and mixed and dissolved again.

Therefore, according to this embodiment, an oil separator or the like is unnecessary, and unlike the prior art shown in FIG. 6, the oil reservoir is not provided at the bottom of the liquid receiver, and the localization by the double riser 17 is not required. Even if a temporary oil reservoir 172 is provided, since it is mixed and dissolved again and introduced into the compressor 11 side, an oil recovery mechanism and a return circuit for returning to the compressor 11 side are unnecessary,
The cycle configuration is extremely simplified.

In this embodiment, since the refrigerant is compatible with the lubricating oil even at the evaporation temperature or lower, it is possible to adopt a top feed structure for introducing the decompressed refrigerant after passing through the expansion valve 13 from above the evaporator 15. Therefore, the refrigerant can pass through the evaporator along the gravity, so that it is not necessary to adopt a so-called full structure, and in the experiments performed by the present inventors, the weight ratio was 10% as compared with the conventional example shown in FIG. %, The refrigeration effect higher than that of the above conventional example could be obtained.

In this embodiment, even if the ammonia refrigerant and the lubricating oil are filled at a ratio of 90 parts by weight to 10 parts by weight, a certain amount of the lubricating oil is stored in the compressor 11 during the refrigeration cycle. The weight ratio of the working fluid composition circulating in the evaporator is lower than the filling weight ratio, and particularly, the mixing ratio circulating in the evaporator is 5% or less, so that the heat transfer efficiency on the evaporator side is further improved. The compressor is suitable for a rotary compressor of a variable blade type or a reciprocating compressor. Further, in the present embodiment, the operation was performed with the evaporation temperature being -15 to -20 ° C. and the compression ratio being higher than that of the conventional technique. However, even with such a configuration, the working fluid may be deteriorated or sludge may be formed. And high reliability can be obtained over a long period of time.

Further, the lubricating oil does not adhere to the wall of the heat exchange coil in the pre-condenser 12 and the evaporator 15, and the heat transfer efficiency is lower than that of the conventional example shown in FIG. 6 using a naphthenic mineral oil-based refrigerating machine oil. It has improved by more than 60%. Further, since the ammonia and the lubricating oil constituting the working fluid have the ability to dissolve water, it is not necessary to provide a dehumidifying agent such as silica gel or a dehumidifying mechanism as in a CFC-based refrigeration cycle.

It is necessary to increase the proportion of the refrigerant in the working fluid as long as the lubricity of the compressor 11 is not reduced.
Practically, when the lubricating oil content is 5% by weight or less, the lubricating ability is reduced. Therefore, in such a case, as described above, 2 to 3% by weight of a cluster diamond having an average particle size of about 50 ° or less or a carbon cluster diamond having a graphite coating on the cluster diamond is added to the lubricating oil. Thereby, the mixing ratio of the lubricating oil in the working fluid could be further reduced.

The double riser 17 also uses a liquid refrigerant after passing through the condenser 14 to heat the working fluid composition containing oil slightly separated by evaporation in the evaporator 15 as shown in FIG. By heating with the exchanger 150, the separated oil melts again in the composition, and the double riser becomes unnecessary. In order to improve the lubricity, the mixing ratio of the lubricating oil in the working fluid composition was increased, and the oil separated by the oil separator 25 and the oil separated by the separator 25 was compressed again at the outlet of the compressor. A measure may be taken to provide a return circuit 26 for returning to the machine 11 side.

In particular, in the case of an oil-cooled screw compressor,
At the outlet side of the compressor 11, an oil separator 25 and the separator 25
It is preferable to provide a return circuit 26 for returning the oil separated in step 2 to the compressor side again. In this case, even if the filling weight ratio of the ammonia refrigerant and the lubricating oil is 90 to 80 parts by weight: 10 to 20 parts by weight, lubrication in the closed cycle of the compressor 11 / oil separator 25 / return circuit 26 is performed. The mixing ratio of the oil is increased, and the mixing ratio of the lubricating oil of the other refrigeration cycle is minimized. For example, the mixing ratio of the lubricating oil on the compressor 11 side is 90% or more, and the lubricating oil ratio on the evaporator 15 side is 3% or less. 0.5%
It is also possible to set to about.

As shown in Examples 4, 6, 7, and 8 in the above table, the construction of the liquid pump recirculation system is achieved by using a lubricating oil having a two-layer separation temperature of −50 ° C. or less. The cryogenic refrigeration system can be easily configured without taking any additional steps. The configuration will be briefly described with reference to FIG.
Is a cryogenic refrigeration system in which R-717 (ammonia refrigerant) as a refrigerant and the polyether of Example 6 as a lubricating oil are filled in a refrigeration cycle in a ratio of 95 parts by weight: 5 parts by weight, and 21 is a low-stage refrigeration system. The compressed working fluid in which the ammonia refrigerant and the lubricating oil are dissolved in the compressor is -10 in the intercooler 22.
After cooling to about ° C., it is guided to the high-stage compressor 11. The refrigerant working fluid compressed by the high-stage compressor 11 is directly led to the condenser 12, where it is condensed by heat exchange (acquisition heat: about 35 ° C.) with cooling water (cooling water pipe 18) in the condenser 12. Liquefied.

The condensed working fluid is supplied to the high-pressure receiver 1
After being stored in the evaporator 15, the working fluid liquefied by the cooling is evacuated and vaporized by the expansion valve 20 to cool the intermediate cooler 22 to about −10 ° C. After being introduced into the evaporator 15 by a top feed and exchanging heat (acquired heat: −50 ° C.) with a blowing load supplied from a fan 16, the air is sucked into a suction side of a compressor 21 through a double riser 17, and is sucked. Repeat the refrigeration cycle. Therefore, also in this embodiment, the oil pool and the oil recovery structure in the high-pressure receiver 14 and the intercooler 22 are not required, and the refrigerant liquid between the low-pressure receiver and the evaporator is different from the prior art shown in FIG. A liquid pump recirculation cycle for circulating water is not required, and the refrigeration cycle configuration is greatly simplified.

The working fluid composition used in this example is shown in Table 3.
As shown in the figure, since the fluidity is good even at −50 ° C. below the evaporation temperature and the fluidity is good at around 4.5 seconds, a top feed structure can be adopted to reduce the amount of refrigerant. However, a higher refrigeration effect than the conventional example of the bottom feed structure can be obtained, and the heat transfer efficiency in the cryogenic evaporator can be improved.

[0073]

[Table 3]

Further, since it is sufficient to provide only a local oil reservoir such as a double riser provided on the outlet side of the evaporator 15 and a remixing / melting structure, the continuous operation of the refrigeration cycle without stopping temporarily for draining the oil. Can be continued for a long period of time, which facilitates unmanned operation and free maintenance.

By adopting the above configuration, the problem with respect to the insolubility of ammonia and the refrigerant has been solved. However, the problem of the strong corrosiveness and conductivity of ammonia, especially the corrosion of copper wire, has not been solved, and unless it is solved, it is difficult to apply it to hermetic compressors, especially household refrigerators. It is. The first is the application of canned motors. That is, in a sealed electric motor directly connected to a fluid machine using an ammonia refrigerant, a cylindrical cylindrical can is fitted and fixed between the stator and the rotor, and the ammonia refrigerant does not leak to the stator located on the outer peripheral side of the can. The adoption of a can-shaped motor having such a configuration will be considered.

However, in the can, a high-density alternating magnetic flux is interlinked, and the eddy current loss and the magnetic resistance in the air gap including the can are increased. Decrease efficiency. Therefore, there is no particular problem if the partition between the stator and the rotor can be formed without using a can and the leakage of ammonia on the stator side can be sealed.

FIG. 4 and FIG. 5 show an embodiment of such a construction, which shows the main construction of a hermetic compressor in which an electric motor and a screw compressor are directly connected. First, the construction on the screw compressor A side will be described. Is a suction hole which is taken in to compress the compatible working fluid as shown by an arrow, 32 is a discharge port for discharging the refrigerant gas compressed by the screw rotor 30 to the condenser side, and 33 is a cover for this. A rotor housing 34A is a bearing fitted to a disc-shaped bearing housing 35, and supports a rotor shaft 37a in which a rotating shaft 36 of the electric motor B is fitted with a sprocket shaft. Also, the rotor shaft 3 on the other side
7b is supported by a bearing 34B. In this case, an incomplete sealing state is formed between the rotor shaft 37a and the bearing 34A,
The working fluid composition can be introduced from the compressor A side to the electric motor B side.

A return hole 39 for the working fluid flowing to the electric motor B is provided below the disc-shaped bearing housing 35 to equalize the pressure of the rotor 41 between the compressor A and the electric motor. . On the other hand, the motor B side includes a rotor 41 fixed to the rotating shaft 36, and a stator 4 surrounding the rotor 41.
As shown in FIG. 5, the stator 42 includes a stator core 43 formed by laminating a plurality of field core plates 43a, and an inner peripheral surface side of the stator core 43, Winding 4 housed in open groove 44 having a U-shaped cross section extending in the axial direction
5 and 45 positioned on both axial sides of the stator core 43.
a is a portion where the coil of the winding is extended.

The stator core 43 is formed by applying an insulating resin coating agent or other adhesive 46 on the lamination surface of a large number of field core plates 43a so as to be airtightly sealed or heat-meltable. The two are integrally solidified by thermocompression bonding with the insulating film 46 interposed therebetween, and are airtightly maintained with pressure resistance. Further, the non-magnetic thin plate 47 or the resin thin film 47 is press-fitted on the inner peripheral surface side of the stator core 43 to form a coating, thereby further improving the airtightness.

The stator core 43 has a substantially cylindrical shape, and has both ends in the axial direction at the bearing housing 3 on the compressor A side.
The flange 48a of the outer frame housing 48, which is hermetically fixed to the housing 5, and the flange portion 28a of the end plate housing 28, which is integrated with the free end bearing 29 of the rotary shaft 36, are integrally and hermetically sealed. To be fixed.

According to this configuration, the stator core 43
Are integrally fixed to the outer frame housing 48 airtightly fixed to the compressor A side and the end plate-shaped housing 28 located at the free end side of the rotary shaft 36 as described above. In addition, it can function as a pressure vessel by cooperating with these members, so that the compression of the refrigerant gas is
Sufficient pressure resistance can be ensured even for refrigerators as large as m ² .

On the other hand, since the winding 45 housed in the open groove 44 of the stator core 43 is located in the same space as the rotor 41, the rotor of the compressor A is in an imperfectly sealed state. Since the working fluid composition containing the corrosive ammonia refrigerant intrudes into the electric motor B from between the shaft 37a and the bearing 34, it is necessary to perform a corrosion-resistant insulation treatment together with the rotor 41 and the winding 45. In addition, it is difficult to insulate the winding from ammonia.

Then, as shown in FIG. 5B, the binding resin 49 is filled in the open groove 44 and the insulating resin thin film 47 ′ is coated on the inner peripheral side thereof to seal airtightly. As shown in FIG.
4 is filled with a binding resin, and
Seal plate 2 having both sides tapered at the open end of
By fitting 7, the back pressure of the sealing plate 27 is applied from the back side of the seal plate 27 by the refrigerant gas pressure in the container, so that the opening end of the open groove 44 can be fitted and hermetically sealed. As a result, while the stator winding 44 is fixed in the open groove 12, the opening surface thereof is closed, so that it is possible to simultaneously maintain strong mechanical strength, touch resistance and airtightness.

[0084]

According to the present invention, it has excellent dissolution stability even at a low temperature with ammonia, exhibits excellent lubricity under an ammonia refrigerant atmosphere, and has no solid matter generated during compressor operation. . Therefore, the oil recovery device, which was indispensable in the conventional ammonia refrigerant refrigeration device, can be omitted,
Therefore, it can be applied as a small refrigerator. As a result, simplification of device configuration and improvement of heat transfer efficiency, etc.
It is possible to provide a refrigeration apparatus that is extremely advantageous in practical use. In particular, according to the present invention, the insolubility as well as the insolubility of the ammonia in lubricating oil is eliminated, whereby an ammonia sealed compressor can be easily provided, and its practical value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a single-stage compression type direct expansion refrigeration apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a two-stage compression type cryogenic freezing apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic view showing a single-stage compression type direct expansion refrigeration apparatus according to another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a hermetic compressor directly connected to an electric motor according to an embodiment of the present invention.

FIG. 5 is an enlarged view of a main part showing a cross-sectional structure of the stator of FIG. 4;

FIG. 6 is a schematic view showing a single-stage compression type direct expansion refrigeration apparatus according to the related art.

FIG. 7 is a schematic view showing a two-stage compression type cryogenic freezing apparatus according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Refrigerant compressor 12 Condenser 13 Expansion valve 14 High pressure receiver 15 Evaporator 15a Inlet 16 Fan 17 Double riser

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisashi Yano 3-17-35 Nishinaminami, Toda City, Saitama Prefecture (56) References European Patent Application Publication 490810 (EP, A1) (58) Fields investigated (Int .Cl. ⁷ , DB name) F25B 1/00 C09K 5/04 C10M 107/34

Claims (8)

(57) [Claims] 1. A refrigerant compressor, a condenser, a refrigeration cycle including an expansion valve and an evaporator, in the ammonia refrigeration system constitutes a refrigeration or heat pump cycle, in it with ammonia refrigerant in the refrigeration cycle Jun
A working fluid composition comprising a lubricating oil;
When the base oil is a polyoxyalkylene glycol terminal OH
At least a part of the hydrogen of the group is a hydrocarbon having 1 to 6 carbon atoms
One or more polyethers blocked by groups
Ter compound, and ammonia in the refrigeration cycle
The weight ratio of the near refrigerant to the lubricating oil is 70:30.
To 97: 3, the refrigeration cycle
Ammonia refrigerant and lubricating oil in it
No separation of two layers even at the evaporation temperature of ammonia refrigerant
An ammonia refrigeration apparatus characterized by having the following configuration . 2. The ammonia refrigeration apparatus according to claim 1, wherein the weight of the lubricating oil in the working fluid composition supplied to the refrigerant compressor side is at least 10%, and is introduced into the ammonia refrigeration cycle via the compressor. Wherein the weight ratio of lubricating oil in the working fluid composition is set to 7% or less. 3. The ammonia refrigeration apparatus according to claim 1, wherein the working fluid composition in which the ammonia refrigerant and the lubricating oil condensed in the condenser are dissolved without separating the refrigerant and the lubricating oil from each other. An ammonia refrigeration system, which is introduced into a cooler. 4. The ammonia refrigeration apparatus according to claim 3, wherein the working fluid composition in which the ammonia refrigerant and the lubricating oil having passed through the expansion valve or the intercooler is dissolved is disposed at a bottom from an inlet provided at an upper end side of the evaporator. An ammonia refrigerating apparatus characterized in that it can be introduced by a top feed toward a discharge port side provided on a side. 5. The compressor, after exchanging the working fluid composition derived from the evaporator, in which the ammonia refrigerant and the lubricating oil are dissolved, with the heat retained in the working fluid composition after condensation in the condenser. The ammonia refrigeration apparatus according to claim 1, wherein the ammonia refrigeration apparatus is configured to be able to be introduced into the apparatus. 6. The ammonia refrigerating apparatus according to claim 1, wherein ultrafine diamond having an average particle size of 150 ° or less is added to said lubricating oil. 7. The ammonia refrigerating apparatus according to claim 1, wherein the hermetic ammonia compressor comprises a hermetic ammonia compressor, a stator and a rotor.
It is configured by directly connecting a pressure-sealed motor,
The inner side of the stator core located around the rotor
Surrounding the rotor with a predetermined gap through a conductive seal portion.
And the composition is introduced between the rotor space and the compressor.
Ammonium characterized by having a conductive part that can pass through
A refrigeration equipment. 8. The ammonia refrigeration apparatus according to claim 1, wherein the hermetic ammonia compressor and the electric motor are directly connected,
A stator core positioned around the rotor is provided on the motor side.
In addition to being configured as a pressure-sealed structure container, the fixed core
Sealing part on the front side facing the rotor of the groove after inserting the winding
Material, and a secret seal is provided in the groove through the seal member.
Ammonia cooling characterized by being configured to
Freezing equipment.