JPH11108507A - Air conditioner - Google Patents

Abstract

(57) [Problem] In a multi-type heat pump air conditioner in which surplus refrigerant is controlled by a receiver, abrasion of a desiccant without being affected by a refrigerant in a liquid pipe becoming a gas-liquid two-phase flow during a heating operation. The following describes how to install a dryer to prevent the occurrence. In an outdoor unit having an accumulator, a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion device, and a receiver, a dryer in which a desiccant for reducing the amount of water in a refrigeration cycle is enclosed is subjected to the outdoor expansion. A device is provided between the device and the receiver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type heat pump type air conditioner in which a plurality of indoor units are operated simultaneously or individually using a vapor compression refrigeration cycle, and more particularly, to a dryer for adsorbing moisture in a refrigeration cycle. And an air conditioner installed in the middle of a liquid refrigerant pipe.

[0002]

2. Description of the Related Art When moisture is present in a refrigeration cycle,
Acid is generated as a cause of decomposition and deterioration of the refrigerant and oil, causing accelerated wear of sliding parts, dielectric breakdown due to corrosion of electrical insulating material, copper plating phenomenon of sliding parts, freezing of water itself, The formation of hydrates causes clogging of the expansion device, strainer, and the like, which causes a failure and significantly lowers reliability. In order to avoid this, a method of installing a dryer for reducing the moisture in the refrigeration cycle has been adopted.

In a multi-type heat pump type air conditioner that performs simultaneous operation or individual operation by connecting a plurality of indoor units, the required amount of refrigerant changes according to the number of operating indoor units and changes in operating conditions. A receiver for storing the surplus refrigerant is provided between the outdoor expansion device and the indoor expansion device. In order to make the surplus refrigerant control of the receiver effective, it is necessary to perform control so that expansion is mainly performed by the indoor expansion device during the cooling operation, while expansion is mainly performed by the outdoor expansion device during the heating operation. As a result, the liquid refrigerant always flows through the liquid refrigerant pipe constantly in both the cooling operation and the heating operation.

On the other hand, it is preferable to install the dryer at a portion where the state of the refrigerant passing through the dryer is a liquid refrigerant. This is preferable from the viewpoints of moisture adsorption performance and prevention of abrasion of the desiccant since the probability of contact with moisture is high because the density of the refrigerant is high, and the flow velocity is low. In a multi-type heat pump air conditioner having a portion through which a liquid refrigerant flows in both cooling and heating operations, a method of installing a dryer in the middle of a liquid refrigerant pipe is disclosed in
No. 27187, and Japanese Patent Application Laid-Open No. 9-21556. In these conventional techniques, the dryer is installed at a position downstream of the receiver during the cooling operation in the outdoor unit.

[0005]

In the above prior art, no consideration is given to the prevention of abrasion of a desiccant against a two-phase flow of a liquid refrigerant pipe generated during a heating operation. That is, during the heating operation, strictly, no consideration is given to the fact that the liquid refrigerant pipe between the indoor expansion device and the receiver is not a complete liquid single phase but a two-phase flow. To explain this, the surplus refrigerant adjustment function of the receiver is described below.

[0006] The amount of surplus refrigerant stored in the receiver is governed by the degree of cleanness of the inflow refrigerant and the amount of heat released to the periphery of the receiver. That is, when the degree of dryness of the inflowing refrigerant is not 0 and air bubbles enter, the air bubbles reach the upper gas layer in the receiver container, and the gas refrigerant accumulates here. This gas refrigerant exchanges heat with the surroundings of the receiver container via the inner wall surface of the receiver container and the liquid layer refrigerant, but in normal operation, the temperature inside the receiver container is higher than the surrounding temperature, so the gas refrigerant releases heat and condenses. Then, a part becomes a liquid refrigerant and is absorbed by the liquid layer.
When the amount of condensed gas refrigerant and the amount of gas bubbles of the inflowing gas refrigerant are not balanced, for example, the inflowing gas refrigerant increases the amount of gas refrigerant in the receiver container.
This pushes down the liquid level and releases the liquid refrigerant in the receiver container.

As a result, the amount of the refrigerant circulating in the refrigeration cycle increases, and when the amount of the refrigerant reaches an appropriate amount, the degree of the refrigerant flowing into the receiver decreases, and the amount of the bubbles decreases, so that the liquid level of the receiver is stabilized. As described above, the degree of heat dissipation of the receiver determines the degree of cuteness of the refrigerant flowing into the receiver. By the way, during the heating operation, the outside air temperature is low, the temperature difference with the refrigerant in the receiver is large, and the amount of heat released to the surroundings increases, so that more gas refrigerant can be condensed in the receiver. As a result, the refrigerant flowing into the receiver has a higher degree of dryness, resulting in a gas-liquid two-phase flow with more bubbles.

In the prior art, a dryer is installed at the receiver inlet side during the heating operation in which the gas-liquid two-phase flow having a relatively large degree of dryness is provided. Therefore, the flow rate of the refrigerant passing through the desiccant is reduced. Since higher speed is achieved by mixing the low gas refrigerant, the fluid force on the desiccant increases, which causes abrasion of the desiccant. As a result, abrasion powder of the desiccant is generated and circulates through the refrigeration cycle to reach the compressor, causing wear of the sliding parts and clogging of details such as the expansion device. There is a problem that the property is significantly reduced.

Further, in the above-mentioned prior art, no consideration is given to prevention of abrasion of the desiccant due to a change in the flow direction in the dryer due to cooling and heating operations. In order to prevent the abrasion of the desiccant, the desiccant is fixed with respect to the wake in the flow direction in both the cooling operation and the heating operation,
It is necessary to have a structure that does not rub.

A first object of the present invention is to provide an air conditioner having a dryer for preventing abrasion of a desiccant during both a cooling operation and a heating operation.

On the other hand, from the viewpoint of protection of the ozone layer, R407C, R407E and R41 which are alternatives to existing refrigerants such as R22.
In HFC (hydrofluorocarbon) -based refrigerants such as 0A, HFC3 whose average molecular diameter is relatively small and is close to water molecules
Contains 2 (difluoromethane) as a component. By the way, used as a desiccant to remove moisture in the refrigeration cycle,
Molecular sieves, which is a kind of synthetic zeolite, has a feature that only molecules passing through pores formed by a dehydrated crystal lattice are adsorbed.

[0012] Because of this sieving effect, since it selectively adsorbs relatively small molecules passing through pores such as water molecules and has a high water adsorption ability even at a low water concentration, it is often used as a desiccant for refrigerant. I have. H whose average molecular diameter is close to water
FC32 is easily adsorbed by the conventional molecular sieve desiccant, not only reduces the water adsorption capacity, but also
There is a problem that FC32 is decomposed to generate harmful substances, which significantly lowers reliability.

[0013] In addition, these HFC-based refrigerants are suitable as refrigerating machine oils which ensure compatibility with the refrigerant and are suitable for oil return.
Ester or ether refrigeration oils are used. By the way, an ester-based refrigerating machine oil generates an organic acid by a hydrolysis reaction, and an ether-based refrigerant generates a peroxide by an oxidative deterioration reaction and is finally oxidized to an acid, thereby reducing the total acid value of the refrigerating machine oil. This raises the problem of raising the wear of the sliding part, causing dielectric breakdown due to corrosion of the electrical insulating material, and causing copper plating on the sliding part. As the material used for the dryer, it is necessary to select a material based on the above. However, the above-mentioned conventional technology does not consider these points.

A second object of the present invention is to provide a desiccant for preventing deterioration of the refrigerant and the refrigerating machine oil and a component of the refrigerating machine oil for improving lubricating properties, and to provide an air conditioner with further improved reliability. It is in.

Further, in order to enhance the performance of the refrigeration cycle, a case where the outdoor unit is provided with a supercooling heat exchanger, or a case where a liquid / gas heat exchanger for exchanging heat between the condensed liquid refrigerant and the low-pressure gas refrigerant is provided. No consideration is given to the above-mentioned conventional technology.

A third object of the present invention is to provide an air conditioner which shows a place where a dryer is installed when a subcooling heat exchanger or a liquid-gas heat exchanger is provided, and further improves performance.

[0017]

In order to achieve the first object of the present invention, an outdoor unit having an accumulator, a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion device, and a receiver is provided.
A plurality of indoor units having an indoor expansion device and an indoor heat exchanger are connected by a liquid connection pipe and a gas connection pipe to constitute a refrigeration cycle in which a refrigerant and a refrigerating machine oil are sealed, and cooling is performed by switching the four-way valve. In a heat pump type air conditioner, an operation or a heating operation is performed, and is mainly expanded by the indoor expansion device during a cooling operation, and is mainly expanded by the outdoor expansion device during a heating operation. Means for providing a dryer in which a desiccant for reducing the amount is enclosed between the outdoor expansion device and the receiver is adopted.

By installing a dryer at this position, during the heating operation, the liquid single-phase refrigerant derived from the bottom of the receiver passes through the dryer, so that a gas-liquid two-phase flow as described in the above problem may occur. Absent. In the cooling operation, the outside air temperature is higher than in the heating operation, so that the temperature around the receiver container is high and the amount of gas refrigerant condensed in the receiver container is small. For this reason, even when the dryer is on the inlet side of the receiver during the cooling operation, the refrigerant is in a state of a liquid single phase with almost no air bubbles. As described above, the wear of the desiccant can be substantially prevented from occurring during the cooling and heating operations.

Further, in order to achieve the first object of the present invention, the dryer is provided with a valve so that the passage direction of the refrigerant in the desiccant is rectified in one direction in either the cooling operation or the heating operation. Means including a refrigerant circuit by a mechanism is adopted.

According to this means, since the passage of the refrigerant through the desiccant is always one direction, the method of fixing the desiccant becomes easy, and the movement of the desiccant due to the change in the flow direction is suppressed. A great effect can be obtained for the prevention of wear of the agent.

In the present invention, the means for setting the connection portion of the dryer so that the dryer can be replaced is adopted when replacing the compressor or cycle parts.
Replace the dryer with a new one and restore the water removal ability.
This is indeed the preferred form, since it is possible to remove water mixed during the replacement operation. The exchangeable connection form includes, for example, a connection method using a union and a flare nut.

Next, in order to achieve the second object of the present invention, when an HFC-based refrigerant is used
When an HFC-based mixed refrigerant containing No. 2 is used, a means using NaA-type molecular sieves having a K cation exchange rate of 0.25 or more as a desiccant is employed. Further, the desiccant has a molecular sieve crystal of 50% or more, and a means that does not use an alumina or phosphoric acid-based substance as a binder connecting the crystals is employed.

The NaA-type molecular sieve has a pore diameter of about 4 ° due to Na (sodium) cation in the crystal lattice. Therefore, the average molecular diameter of H
FC32 passes easily. However, by replacing the Na cation with the K (potassium) cation, the pore diameter can be further narrowed, and the pore diameter can be reduced to 3 mm. In order for most Na cations affecting the pore diameter to be replaced by K cations, the exchange rate must be 0.25,
In order to reduce the amount of HFC32 adsorbed, the K cation substitution rate was set to a higher value.

When alumina or phosphoric acid is used as a desiccant binder, it not only promotes deterioration of ester or ether refrigerating machine oils, but also adsorbs and consumes acid scavengers and extreme pressure additives. Therefore, it is effective to prevent the deterioration of the refrigerating machine oil by including not only these but also a large amount of molecular sieve crystals of 50% or more.

Further, in order to achieve the second object of the present invention, means for using an ester-based refrigerating machine oil as the refrigerating machine oil is employed.

The ester refrigerating machine oil is mainly composed of an ester obtained by subjecting a polyhydric alcohol such as pentaerythritol or trimethylolpropane to an esterification reaction of a linear or branched fatty acid having 5 to 9 carbon atoms. It is a refrigerating machine oil that has high compatibility with HFC-based refrigerants having large molecular polarization due to the polarization action of carbonyl groups in the molecular structure, and has excellent load resistance. When used in combination with the dryer of the present invention, the water that causes the hydrolysis is reduced, so that the hydrolysis of the ester can be suppressed and the generation of organic acids can be prevented.

Further, in order to achieve the second object of the present invention, means for using an ether-based refrigerating machine oil as the refrigerating machine oil is employed. Use a means of adding 1% or more.

The ether-based refrigerating machine oil is a refrigerating machine oil containing a linear or cyclic hydrocarbon containing an ether bond in a molecular bond as a main component, and is compatible with an HFC-based refrigerant having a large molecular polarization by its polarization action. Is high. When used in combination with the dryer of the present invention, moisture, which is a factor of acceleration of oxidative deterioration, is reduced, so that oxidative deterioration can be suppressed and generation of organic acids can be prevented. Furthermore, even if a phosphate ester-based extreme pressure additive for improving load resistance, for example, TCP (tricresyl phosphate) is added, it is possible to prevent hydrolysis by reaction with moisture. It can work effectively. The addition of 0.1% or more, which is effective in improving the lubricity by the phosphate extreme pressure additive, is effective.

Next, in order to achieve the third object of the present invention, means for providing a supercooling heat exchanger between the outdoor expansion device and the dryer is employed.

In order to further achieve the third object of the present invention, a low-pressure gas refrigerant upstream or downstream of an accumulator is provided.
In the cooling operation, a means including a liquid-gas heat exchanger for performing heat exchange with the high-pressure liquid refrigerant downstream of the receiver is employed.

By using a supercooling heat exchanger and a gas-liquid heat exchanger, a higher heat exchange efficiency can be obtained, which is a very effective means for improving the performance of an air conditioner.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a refrigeration cycle showing a first embodiment of the present invention. 1 is an inverter variable displacement compressor, 2 is a constant speed compressor, 3 is an accumulator, 4 is an oil tank, 5 is a four-way valve, 6 is an outdoor heat exchanger, 7 is an outdoor blower, 8 is an outdoor expansion device, and 9 is excess. Cooling heat exchanger, 1
0 is dryer, 11 is moisture indicator, 12
Is a receiver, 13 is a gas-liquid heat exchanger, 14 is a liquid check valve,
Reference numeral 20 denotes a gas check valve, which constitutes an outdoor unit 21. Further, 16a and 16b are indoor expansion devices, 17a and 17b are indoor heat exchangers, and 18a and 18b are indoor blowers, which constitute indoor units 22a and 22b.

Further, the indoor units 22a and 22b are connected to the outdoor unit 21 by a liquid connection pipe 15 and a gas connection pipe 19,
Air conditioning is performed by operating either the inverter variable displacement compressor 1 or the constant speed compressor 2 or simultaneously and operating the outdoor blower 15 and the indoor blower 16.

As the refrigerant used as the working fluid, it is preferable to use a refrigerant composed of hydrofluorocarbon (HFC) which does not destroy the ozone layer.
C, R407E, R410A, R404A, R507A
In this embodiment, difluoromethane (HF) is used.
C32), pentafluoroethane (HFC125),
1,1,1,2-tetrafluoroethane (HFC134
R407C is used in which each of the three types a) is composed of 23: 25: 52% by weight.

As a refrigerating machine oil to be combined with a refrigerant, it is effective to use a compatible ester, ether or carbonate refrigerating machine oil from the viewpoint of oil return in the refrigerating cycle. These refrigerating machine oils are HF
In order to have solubility with the C refrigerant, a polar molecule such as a carbonyl group or an ether bond by introducing an oxygen atom is used for the base material. In this embodiment, an ether-based refrigerator oil is used. Furthermore, a phosphate ester-based extreme pressure additive TCP (tricresyl phosphate) was added to this refrigerator oil at 0.3.
Use the added product.

As the desiccant of the dryer 10, NaA type molecular sieves having a K cation exchange rate of 0.25 or more is used. Further, a desiccant having a molecular sieve crystal of 50% or more and using no alumina or phosphoric acid-based substance as a binder connecting the crystals is used.

Next, the operation of the present invention will be described. First, in the case of the cooling operation, the gas refrigerant discharged from the inverter variable displacement compressor 1 or the constant speed compressor 2 is condensed in the outdoor heat exchanger 6. The condensed liquid refrigerant is not throttled by the outdoor expansion device 8, becomes a liquid refrigerant of almost zero cuteness in the supercooling heat exchanger 9, passes through the dryer 10, and is dehydrated. During the cooling operation, the outside air temperature is higher than during the heating operation.
The temperature around the container is high, and the amount of gas refrigerant condensed in the receiver container is small.

For this reason, even when the dryer 10 is on the receiver inlet side during the cooling operation, the refrigerant near the liquid single phase containing almost no air bubbles passes therethrough, so that the desiccant does not wear. The liquid refrigerant that has exited the receiver 12 is further radiated and supercooled in the gas-liquid heat exchanger 13, so that the refrigerant expanded in the indoor expansion devices 16a and 16b is used in the indoor heat exchanger 17 of the refrigerant.
Since the specific enthalpy at the inlets a and 17b is reduced, the latent heat of the refrigerant is effectively used, and the performance is improved.

The gas refrigerant evaporated and vaporized in the indoor heat exchangers 17a and 17b returns to the outdoor unit 21 and is returned to the gas liquid heat exchanger 13
Since the heat is received from the liquid refrigerant and heated, the degree of superheat at the compressor suction section is moderate, and the compressor is not wet-compressed, so that the compressor can be operated under high efficiency conditions and the performance is improved. Further, since the liquid refrigerant is less likely to be stored in the accumulator 3, the composition fluctuation peculiar to the non-azeotropic refrigerant can be prevented.

Next, the case of the heating operation will be described. The gas refrigerant discharged from the inverter variable displacement compressor 1 or the constant speed compressor 2 is condensed in the indoor heat exchangers 17a and 17b. In the heating operation, since the outside air temperature is low, the heat radiation amount of the receiver 12 also increases, the amount of gas refrigerant condensed in the receiver 12 container increases, and the refrigerant passing through the liquid connection pipe 15 and the like,
It is a gas-liquid two-phase. However, the outlet pipe of the receiver 12 draws out the lower liquid refrigerant and reaches the dryer 10, so that the refrigerant passing through the dryer 10 becomes almost zero in the liquid refrigerant, and the desiccant does not wear. Further, since the liquid refrigerant is supercooled by the supercooling heat exchanger 9, the specific enthalpy of the liquid refrigerant is reduced, and the latent heat of the refrigerant is effectively used, thereby improving the performance.

In this embodiment, since the moisture which is a factor of acceleration of the oxidative deterioration is reduced by the dryer 10, the oxidative deterioration can be suppressed and the generation of the organic acid can be prevented. Further, since the phosphate extreme pressure additive can be prevented from reacting with water and being hydrolyzed, the additive can also act effectively.

Further, since the K (potassium) cation substitution rate of the desiccant NaA type molecular sieve is 0.25 or more, the pore diameter of the molecular sieve can be about 3 mm, and the average molecular diameter is 3.3 mm. Since the adsorption amount of HFC32 has been reduced, it is possible to reduce the water adsorption capacity,
FC32 can be almost completely decomposed to generate harmful substances.

Further, since the binder of the desiccant does not use alumina or a phosphoric acid-based substance and uses a desiccant containing at least 50% of molecular sieve crystals, deterioration of the refrigerating machine oil is not promoted. In addition, the acid scavenger, extreme pressure additive and the like are not significantly reduced, and the refrigerating machine oil is not deteriorated.

FIG. 2 is a configuration diagram showing a first example of a dryer used in the first embodiment of the present invention. 30 is a container, 31 is a desiccant, 32 is a filter, 33, 34, 3
Reference numerals 5 and 36 denote rectifying valves, and 37 denotes a union.

FIG. 3 is a configuration diagram showing a second example of a dryer used in the first embodiment of the present invention. 40 is a container, 41 is a desiccant, 42 is a filter, 43 is a spring, 44
Denotes a flare joint, and 45 denotes a check valve.

The rectifying valve 33,
Due to the rectifying effects of the valves 34, 35, 36 and the check valve 45, the refrigerant flows in the direction of the solid arrow during cooling and in the direction of the dotted arrow during heating. According to the present embodiment, the passage direction of the refrigerant in the desiccants 31 and 41 is always one direction.
Since the method of fixing the desiccant becomes easy and the movement of the desiccant due to the change in the flow direction is suppressed, a great effect can be obtained in preventing the desiccant from being worn.

In this embodiment, the dryer container 3
Since the connection portion of 0, 40 is a connection method using a flare nut that can replace the dryer, when replacing the compressor or cycle parts, the dryer is also replaced with a new one to restore the moisture removal ability, Since moisture mixed during the replacement operation can be removed, reliability can be improved.

[0048]

According to the present invention, since the abrasion of the desiccant can be prevented, the abrasion of the sliding portion does not increase and clogging of the details does not occur, and the degradation of the refrigerant and the refrigerating machine oil is prevented.
Since the effect of the additive can be maximized, a highly reliable air conditioner can be obtained.

Further, according to the present invention, since the heat exchange performance can be effectively brought out, an air conditioner with further improved performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a first example of a dryer used in the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a second example of a dryer used in the first embodiment of the present invention.

[Explanation of symbols]

1 ... Inverter variable displacement compressor, 2 ... Constant speed compressor, 3
... accumulator, 4 ... oil tank, 5 ... four-way valve, 6
... outdoor heat exchanger, 7 ... outdoor blower, 8 ... outdoor expansion device,
9 ... Supercooling heat exchanger, 10 ... Dryer, 11 ... Moisture indicator, 12 ... Receiver, 13 ... Gas liquid heat exchanger, 14 ... Liquid check valve, 15 ... Liquid connection piping, 16a, 1
6b indoor expansion device, 17a, 17b indoor heat exchanger,
18a, 18b: indoor blower, 19: gas connection pipe, 2
0: gas check valve, 21: outdoor unit, 22a, 22b: indoor unit, 30, 40: container, 31, 41: desiccant, 32, 4
2. Filter, 33, 34, 35, 36 ... Rectifying valve, 37
... union, 43 ... spring, 44 ... flare joint, 45 ... check valve.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Susumu Nakayama 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. (72) Inventor Hiroaki Tsuboe 390 Muramatsu, Shimizu-shi, Shizuoka Air Conditioning System, Hitachi, Ltd. Within the business division

Claims (1)

[Claims] An outdoor unit having an accumulator, a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion device, and a receiver, and a plurality of indoor units having an indoor expansion device, an indoor heat exchanger,
A refrigeration cycle in which a refrigerant and a refrigerating machine oil are sealed is connected by a liquid connection pipe and a gas connection pipe, and a cooling operation or a heating operation is performed by switching the four-way valve. During the cooling operation, the indoor expansion device is mainly used. In the heat pump type air conditioner, which is expanded mainly by the outdoor expansion device during the heating operation, the dryer in which the desiccant for reducing the amount of water in the refrigeration cycle is enclosed is subjected to the outdoor expansion. An air conditioner provided between a device and the receiver.