The present invention relates to a refrigerating cycle device such as an air conditioner, a water heater and the like. Particularly, reliability of a refrigerating cycle device is improved by providing removing means for removing substances that react with an unstable refrigerant.
In general, in a refrigerating cycle device using a refrigerating cycle (heat-pump cycle) such as an air conditioner, a freezer, a water heater and the like, basically, a compressor, a condenser (heat exchanger), an expansion valve, and an evaporator (heat exchanger) are connected by piping so as to constitute a refrigerant circuit through which a filled refrigerant is circulated. The refrigerant compressed an the compressor becomes a high-temperature and high-pressure gas refrigerant and is fed into the condenser. The refrigerant having been fed into the condenser is liquefied by emitting neat through heat exchange with a heat-exchange target. The liquefied refrigerant is decompressed by the expansion valve and turned into a gas-liquid two-phase flow state and gasified (evaporated) by absorbing heat through heat exchange in the evaporator, returned to the compressor again and circulated.
Here, there are many types of refrigerants circulating through the refrigerant circuit according to applications and physical characteristics, and some of them are refrigerants containing chemical substances affecting global warming. From a viewpoint of preventing global warming, a refrigerant having as small global warming coefficient (GWP: a degree of incurring global warming with respect to a substance, which is a greenhouse effect gas, represented by a coefficient determined on the basis of knowledge internationally approved as numeral values indicating a ratio to the degree regarding carbon dioxide) as possible is preferably used.
For example, carbon dioxide (CO2) has a considerably small global warming coefficient, but efficiency of the refrigerating cycle is lowered and power consumption is increased. Also since pressure resistance of equipment, piping and the like needs to be raised in general as compared with a case using a refrigerant circulated in a refrigerant circuit (R410A refrigerant, for example), a weight of the entire apparatus is increased, which results in cost-up and prevents popularization.
Then, an HFO (Hydro Fluoro Olefin) refrigerant (hereinafter referred to as an HFO refrigerant) is proposed. The HFO refrigerant has a small global warming coefficient and better energy efficiency than carbon dioxide and is an effective refrigerant from a viewpoint of a global environment. Also since its boiling point is high and pressure of the refrigerant in the refrigerant circuit is law, there is no need to raise the pressure resistance. However, the HFO refrigerant has a characteristic that its chemical reactivity is high due to a double bond in an atomic bond constituting a substance thus, the global warming coefficient gets smaller). Therefore, if impurities other than the refrigerant are present in the refrigerant circuit, the refrigerant reacts with the impurities and is deteriorated, which is a problem.
If the refrigerant is deteriorated, the high pressure gets higher or a discharge temperature becomes higher, and efficiency of the refrigerating cycle is drastically lowered. Also, a chemically reacted new substance further reacts with refrigerant oil, which generates sludge or blocks a thin, pipe such as a capillary tube or an expansion valve, which is a problem.
As mentioned above, the HFO refrigerant has a low warming coefficient, and is environmentally friendly, but deterioration of the refrigerant itself should be prevented in order to be used as a refrigerant in a vapor compression refrigerating cycle, while reliability is ensured. Therefore, in order to prevent circulation of an oxygen component in the refrigerant circuit, a method of providing oxygen adsorbing means for adsorbing oxygen is disclosed (See Patent Document 1, for example).
However, since oxygen is not the only substance to become an impurity in the refrigerant circuit, even if the HFO refrigerant is sealed by adsorbing oxygen as above, it is highly likely that the HFO refrigerant is deteriorated, and efficiency and reliability of a refrigerating cycle device is lowered over time. Thus, in order to prevent deterioration of the HFO refrigerant, further measures are require.
The present invention was made in order to solve the above problems and has an object to obtain a refrigerant cycle device or the like that can prevent impurities contained in a refrigerant circuit from circulating in the refrigerant circuit and can effectively use the HFO refrigerant or the like.
In a refrigerating cycle device according to the present invention, a compressor for compressing a refrigerant containing a hydrofluoroolefin refrigerant, a condenser for condensing the refrigerant by heat exchange, expanding means for decompressing the condensed refrigerant, an evaporator for evaporating the refrigerant by heat exchange between the decompressed refrigerant and air, and air adsorbing means for adsorbing oxygen and nitrogen are connected by piping so as to constitute a refrigerant circuit through which the refrigerant containing the hydrofluoroolefin refrigerant is circulated.
According to the refrigerating cycle device of the present invention, since the air adsorbing means is provided on the refrigerant circuit so as to adsorb an oxygen molecule and a nitrogen Molecule in the air of the refrigerant circuit, the oxygen molecule and the nitrogen molecule to become impurities can be prevented from circulating. Therefore, even if the HFO refrigerant or the like which has double bond and as chemically unstable is circulated through the refrigerant circuit, the HFO refrigerant and the air can be prevented from deteriorating or the like by chemical reaction or the like, performances of the refrigerating cycle device can be maintained for a long time, and moreover, reliability can be ensured. Also, since deterioration of the refrigerant can be prevented and feeding of a heat quantity can be maintained without applying a load on the compressor, energy can be saved. Since the HFO refrigerant such as tetrafluoropropylene used as a refrigerant at this time has a global warming coefficient equivalent to that of carbon dioxide, which is TO a natural refrigerant, for example, and is a so-called nonflon refrigerant, the refrigerant is suitable from a viewpoint of the environment.
An embodiment of the present invention will be described below referring to the attached drawings.
The compressor 1 sucks the refrigerant to be circulated through the refrigerant circuit and compresses and pressurizes it. The condenser 2 performs heat exchange between a gas state refrigerant discharged by the compressor 1 (hereinafter referred to as a gas refrigerant) and a heat-exchange target and emits a heat quantity in the refrigerant so as to heat the heat-exchange target.
The air adsorbing means 3 is means for adsorbing air in the refrigerant circuit. Usually, a vacuuming process is provided before the refrigerant is filled in the refrigerating cycle device in order to vacuum the inside of the refrigerating cycle device. However, even with vacuuming, an air amount in the refrigerating cycle device cannot be brought to zero (fully vacuum state). Actually, approximately 130 to 250 Pa (approximately 1 to 2 Torr) is a limit. Thus, air is present all the time as an impurity in the refrigerant circuit of the refrigerating cycle device. Here, a presence ratio between nitrogen and oxygen in the air is 8:2, and oxygen and nitrogen (particularly nitrogen) occupy the most part. Thus, the air adsorbing means 3 in this Embodiment is supposed to adsorb oxygen molecules and nitrogen molecules. The air adsorbing means 3 will be described later in detail.
The throttle device 4 adjusts a flow rate of the refrigerant and lowers the pressure of the refrigerant (decompression). The evaporator 5 performs heat exchange between a gas-liquid two-phase refrigerant whose pressure is lowered by the throttle device 4 (refrigerant in which a gas refrigerant and a liquid-state refrigerant (hereinafter referred to as a liquid refrigerant) coexist) and a heat exchange target, has a heat quantity absorbed by the refrigerant, evaporated, and gasified. The heat-exchange target is cooled. Here, a level of the pressure in the refrigerant circuit is not determined by a relationship with a pressure to be a reference but is indicated as a relative pressure determined by compression of the compressor 1, refrigerant flow-rate control of the throttle device 4 and the like. The same applies to a degree of the temperature.
Subsequently, an operation of the refrigerating cycle device according to this Embodiment will be described based on a flow of the refrigerant. The refrigerant having been compressed and pressurized by the compressor 1 passes through the piping and is fed into the condenser 2. The refrigerant having passed through the condenser 2 is condensed and liquefied. At this time, the refrigerant omits heat, by which the heat-exchange target is heated.
The liquefied refrigerant passes through the air adsorbing means 3 and is fed into the throttle device 4. The liquid-state refrigerant is decompressed while passing through the throttle device 4, becomes a refrigerant in the gas-liquid two-phase flow state (hereinafter referred to as a gas-liquid two-phase refrigerant) and is fed into the evaporator 5. The gas-liquid two-phase flow state refrigerant having passed through the evaporator 5 is evaporated and gasified). The gasified refrigerant is sucked into the compressor 1 again.
Here, a flow of the refrigerant in the air adsorbing means 3 will be described. As described above, the refrigerant having passed through the condenser 2 flows in through the inflow pipe 3c of the air adsorbing means 3, passes through the filter 3e and flows into the adsorbing material portion 3b. Here, the filter 3e traps a foreign substance lot lowing with the refrigerant and prevents adhesion of the foreign substance to the adsorbing material in the adsorbing material portion 3b. By preventing adhesion of the foreign substance to the adsorbing material portion 3b, deterioration of the adsorbing material can be prevented, and stable performances can be obtained. Then, from the refrigerant flowing into the adsorbing material portion 3b, the adsorbing material, of the adsorbing material portion 3b adsorbs only an air component (oxygen and nitrogen) contained in the refrigerant. The refrigerant whose air component has been adsorbed flows out of the outflow pipe 3d through the filter 3f and is fed into the throttle device 4.
Here, by means of the refrigerant flowing to the adsorbing material portion 3b, the adsorbing material in the adsorbing material portion Oh might be pulverized. If the pulverized adsorbing material flows out of the air adsorbing means 3 and circulates with the refrigerant in the refrigerant circuit, occlusion might be induced in members such as a capillary tube or the throttle device 4, which is a narrow flow passage. Also, it might Cause a failure of the compressor 1. Then, the filter 3f is provided so that the pulverized adsorbing material is trapped and prevented from, flowing out of the air adsorbing means 3. Therefore, the filer if is an important component in ensuring reliability of the air adsorbing means 3 and thus, the refrigerating cycle device.
In this Embodiment, as the adsorbing material in the adsorbing material portion 3h, zeolite which has excellent chemical stability and can strongly adsorb a substance with a low concentration (low partial pressure) is used. A mechanism for adsorbing air by zeolite is adsorption by trapping an oxygen molecule and a nitrogen molecule in a manner of a molecular sieve. Thus, in order to selectively adsorb only air by the adsorbing material 3b, a pore size of zeolite (here, it is supposed to be a diameter) should be not smaller than a diameter according to the air component and smaller than a diameter according to the HFO refrigerant. Due to this restriction, the pore size of the zeolite is inevitably determined. Here, a size of a nitrogen molecule, which is a major component of the air, is approximately 36 nm (3.6 angstrom) and a size of an oxygen molecule is approximately 34 nm (3.4 angstrom). Thus, even if the adsorbing material is optimized from a viewpoint of oxygen adsorption and the pore size of the adsorbing material is set at 35 nm (3.5 angstrom), the nitrogen molecule is larger than the oxygen molecule and cannot be removed. Also, a dryer which has been used is intended to adsorb moisture, and a pore size of the adsorbing material is in the vicinity of 29 no (2.9 angstrom) the size of a water molecule is 2.8 angstrom), therefore the nitrogen molecule and the oxygen molecule cannot be removed. From the above, the pore size of the adsorbing material needs to be approximately 36 nm in accordance with the nitrogen molecule.
On the other hand, the molecular size of the HFO refrigerant is approximately 40 nm. Thus, by setting a pore size dp of the adsorbing material for removing oxygen and nitrogen at 36 nm<dp<40 nm, the air component can be selectively adsorbed. Here, in this Embodiment, zeolite is used as the adsorbing material, but the adsorbing material is not limited only to zeolite. As mentioned above, any adsorbing material such as silica gel, activated coal, mesoporous silica and the like, for example, can achieve the similar effect as long as it has a pore size of 36 nm<dp<40 nm as mentioned above.
An installation position of the air adsorbing means 3 will be described below. In
In the case of an operation to reduce sub-cooling, for example, if the air adsorbing means 3 is installed in the high-pressure liquid line as in the above-mentioned
Also, since the adsorbing material exerts better adsorbing performance if the temperature is lower in general, an amount of the adsorbing material can be reduced under a low-temperature environment if the same amount of air is to be adsorbed, for example. Thus, by installing the air adsorbing means 3 in the low-pressure gas line through which the low-temperature refrigerant passes, the else of the air adsorbing means 3 can be reduced, and costs relating so the air adsorbing means 3 can be declined in tints way, it is only necessary that the air adsorbing means 3 is simply provided on the low-pressure gas line, but the pressure loss generated in the air adsorbing means 3 might give too large impact on the efficiency of the refrigerating cycle device.
Thus, a bypass pipe for bypassing a part of the refrigerant is provided in the low-pressure gas line so as to form a bypass circuit 6, and the air adsorbing means 3 is disposed in the bypass circuit 6. By having a part of the refrigerant pass through the air adsorbing means 3 as above, a refrigerant flow rate passing through the it adsorbing means 3 is reduced, by which the pressure loss by the air adsorbing means 3 in the low-pressure line is decreased and efficiency drop of the refrigerating cycle device is minimized.
Here, as shown in
As mentioned above, according to the refrigerating cycle device of Embodiment 1, by using the HFO refrigerant as a refrigerant circulating through the refrigerant circuit, since it is a so-called non-flon on refrigerant having the global warming coefficient equivalent to that of carbon dioxide, which is a natural refrigerant, the refrigerating cycle device friendly to the global environment can be obtained. Also, since the air adsorbing means 3 is provided in the refrigerant circuit so that the oxygen molecule and the nitrogen molecule in the air remaining in, the refrigerant circuit even after vacuuming, for example, are trapped, the oxygen molecule and the nitrogen molecule to become impurities can be prevented from circulating. Thus, even if the chemically unstable HOP refrigerant or the like having double bond is circulated in the refrigerant circuit, deterioration or the like of the HFO refrigerant and air due to chemical reaction or the like can be prevented. As a result, performances of the refrigerating cycle device can be ensured for a long time, and reliability can be also ensured. Also, deterioration of the refrigerant is prevented, and transportation of the heat quantity can be maintained without giving a load to the compressor 1, and energy saving can be promoted.
Also, since the air adsorbing means 3 is installed in the high-pressure liquid line through which the high-pressure liquid refrigerant flows, the influence of the pressure loss due to the air adsorbing means 3 can be reduced to an negligible level, and the efficiency of the refrigerating cycle device can be prevented from being affected. On the other hand, by installing the means 3 in the low-pressure gas line through which the low-pressure gas refrigerant flows, the low-temperature refrigerant can pass through the air adsorbing means 3, adsorbing performance is improved, and the size of the air adsorbing means 3 can be reduced in installation. Since the bypass circuit 6 is provided so that a part of the gas refrigerant passes through the air adsorbing means 3, the influence of the pressure loss of the air adsorbing means 3 in the low-pressure gas line can be suppressed.
A density of the liquid refrigerant in the HFO refrigerant is approximately 800 to 1100 [kg/m3], for example. On the other hand, the density of air is approximately 1.2 [kg/m3]. Since the air and the liquid refrigerant has a large density difference as above, the liquid refrigerant flowing in through the refrigerant inflow pipe 11d located at the lower part of the container 11c is collected as a liquid refrigerant 12b in the container 11c, and a part of the refrigerant flows out of the refrigerant outflow pipe 11e. The air flowing in together with the liquid refrigerant is collected as air 12a in the upper part of the container 11c. Also, since the refrigerant outflow pipe 11e protrudes inward from the lower part of the container 11c, even if a foreign substance heavier than the refrigerant is contained in the refrigerant for some reason, for example, it does not flow out of the refrigerant outflow pipe 11e but can be collected in the lower part of the container 11c, and removal of the foreign substance can be realized.
By opening the air vent valve ha provided on the upper part of the container 11c, a pressure relating to inflow of the liquid refrigerant through the refrigerant inflow pipe 11d pushes out the air 12a to an external space through the air vent pipe 11b and air is purged. When the air 12a is fully pushed out, the liquid refrigerant is also pushed out, and the air vent valve 11a is closed. As mentioned above, the air remaining in the refrigerant circuit is purged.
The outdoor-side heat exchanger 203 functions as the condenser 2 in Embodiment 1 in the codling operation and functions as the evaporator 5 in the heating operation to perform heat exchange between the air and the refrigerant. Also, the indoor-side heat exchanger 205 functions, to the contrary to the outdoor-side heat exchanger 203, as the evaporator 5 in the cooling operation and functions as the condenser 2 in the heating operation to perform heat exchange between the indoor air and the refrigerant. Also, though not particularly illustrated here, control means for controlling operations of each means is provided. Alternatively, a Can for performing heat exchange with the refrigerant efficiently may be provided in the outdoor-side heat exchanger 203 and the indoor-side heat exchanger 205. Then, in this air conditioner, too, as the refrigerant to be circulated in the refrigerant circuit tetrafluoropropene (tetrafluoropropylene) refrigerant, which is one type of HFO (hydrofluoroolefin) refrigerant, is used.
Subsequently, an operation of the air conditioner according to this Embodiment will be described based on the refrigerant. Arrows along the refrigerant circuit shown in
On the other hand, in the heating operation, the refrigerant flow is reversed by the flow-passage switching valve 202 so that the high-temperature and high-pressure refrigerant gas flows into the indoor unit 200b. At this time, the indoor-side heat exchanger 205 functions an the condenser, while the outdoor-side heat exchanger 203 functions as the evaporator.
Here, the air separating/removing means 11 provided in the air conditioner in
Also, air-purge is most preferably performed by the air separating/removing means 11 in the cooling operation during a trial operation. The air-purge is performed in the trial operation since the earlier the air is removed, the smaller a degree of deterioration of the refrigerant can be.
Also, in the heating operation, for example, the indoor-side heat exchanger 205 becomes the condenser, and the liquid refrigerant is present in the indoor-side heat exchanger 205. Thus, if the indoor unit 200b is installed at a position higher than the outdoor unit 200a, the refrigerant and the air are separated an the indoor unit 200b, and thus, air is not collected in the air separating/removing means 11. On the other hand, if the outdoor unit 200a is installed at a position higher than the indoor unit 200b such as a roof top, by installing the air separating/removing means 11 at a position in front of the throttle device 4, for example, the air can be separated even in the heating operation. However, it is more convenient to perform air-purge in the cooling operation since the installation: positions of the outdoor unit 200a and the indoor unit 200b are not to be worried about.
Also, since the indoor-side heat exchanger 205 becomes the condenser, the air separating/removing means 11 is installed on the piping where the refrigerant returns to the outdoor unit 200a. If the indoor unit 200b is located at a position higher than the outdoor unit 200a, the air separating/removing means 11 might be located below the indoor-side heat exchanger 205. Thus, as shown in
As mentioned above, according to the refrigerating cycle device of Embodiment 2, since the air separating/removing means 11 having the air vent valve ha and the air vent pipe 11b is provided on the refrigerant circuit in order to remove the air remaining in the refrigerant circuit even after vacuuming from the refrigerant circuit, for example, the air to become impurities can be prevented from circulating. Thus, even if the chemically unstable HFO refrigerant or the like having double bond is circulated in the refrigerant circuit, the HFO refrigerant and the air can be prevented from deteriorating or the like by chemical reaction or the like. As a result, performances of the refrigerating cycle device can be maintained for a long time, and moreover, reliability can be ensured. Since the air separating/removing means 11 is provided in a portion through which the liquid refrigerant flows, the refrigerant and the air can be reliably separated on the basis of a difference in density between the liquid refrigerant and the air. Also, by providing the air separating/removing means 11 at the highest position in the refrigerant circuit, the air can be collected in the air separating/removing means 11 and separated efficiently.
In the above Embodiments, the cases in which the air adsorbing means 3 and the air separating/removing means 11 are installed singularly in the refrigerant circuit (refrigerating cycle device) were shown, but the number of installation is not limited to one. Particularly, the air separating/removing means 11 may be provided at plural spots where air can be easily collected.
In, the above Embodiments, the air conditioner has been described in Embodiment 2, but not, limited to that, the air conditioner provided with the air adsorbing means 3 described, in Embodiment 1 can also be realized.
Also, in the above Embodiments, the refrigerant containing tetrafluoropropene (CF3CF═CH2) has been described as the refrigerant containing chemically unstable substance, for example, but the present invention can be also applied to the other HFO refrigerants and the like.
in the above. Embodiments, the application to the air conditioner capable of cooling/heating operations has been described, but the present invention can be also applied to other refrigerating cycle devices configuring a refrigerant circuit such as a heat pump device or the like.
Number | Date | Country | Kind |
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2008-164655 | Jun 2008 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2009/060790 | 6/12/2009 | WO | 00 | 12/2/2010 |