CN1291195C - Refrigerating circulation and heat pump type hot water supply device - Google Patents

Abstract

To provide an environmentally-friendly heat pump water heater capable of assuring a high reliability by sufficiently holding oil film on a compressor sliding part and also capable of saving energy and providing a high efficiency in a heat pump water heater using carbon dioxide refrigerant (CO2). In this heat pump water heater using carbon dioxide refrigerator, either one type of poly [alpha]-olefin or paraffin mineral oil or naphthene mineral oil or alkyl benzene which show the non-compatibility with the carbon dioxide refrigerant or a mixed oil is used as a refrigerator oil. Thus the wear of a compressor can be suppressed, a leak current can be reduced, and a performance can be increased.

Description

Refrigeration cycle and heat pump hot water supply device

technical field

The invention relates to a refrigeration cycle using carbon dioxide refrigerant and a heat pump hot water supply device.

Background technique

The refrigerant of the existing refrigeration cycle widely adopts CFC (Chlorofluorocarbon (Chlorofluorocarbon)) and HCFC (Hydrochlorofluorocarbon (Hydrochlorofluorocarbon)), but from the viewpoint of protecting the ozone layer, All of them are being abolished or reduced.

As an alternative refrigerant, the mainstream is the HFC (Hydrofluoride (Hydrofluorocarbon)) refrigerant that does not contain chlorine and does not destroy the ozone layer. HFC134a (1,1,1,2-tetrafluoroethane) with similar thermodynamic properties is used in refrigerators or automobile air conditioners, and replaces the mixed refrigerant of the HFC series of HCFC22, that is, R410A (HFC32/125:50/50% by weight ) or R407C (HFC32/125/134a: 23/25/52% by weight), etc. are used in room air conditioners or combination air conditioners.

However, although HFC does not destroy the ozone layer, it tends to be restricted from the viewpoint of preventing global warming.

In recent years, carbon dioxide (CO ₂ ) as a natural refrigerant has attracted attention from the viewpoint of protection of the global environment, incombustibility, and low toxicity. Applicable products include electric vehicle air conditioners, heating equipment for cold regions, and hot water supply equipment.

Global environmental issues require more energy saving and higher efficiency. Taking hot water supply equipment as an example, the hot water supply equipment using carbon dioxide heat pump has the advantage of operating The cost can be reduced by about 1/5, and the efficiency coefficient (COP: Coefficient of Performance) can achieve more than 3.0 high efficiency. For example: when the above-mentioned HFC refrigerant is used in a heat pump hot water supply device, due to the thermophysical properties of the refrigerant, it can only supply hot water at a maximum of about 60°C, and a compressor with a high output power is required to obtain a higher temperature . On the contrary, when carbon dioxide refrigerant is used, it has the advantage that hot water of about 90° C. can be output due to the thermophysical properties of the refrigerant.

On the other hand, refrigerating machine oil is used in sealed electric compressors to perform functions such as lubricating, sealing, and cooling the lubricating parts. The compressor using carbon dioxide refrigerant is under high temperature and high pressure (approximately 10MPa), so the operating conditions of the refrigerating machine oil are harsh. Therefore, in order to ensure the reliability of the compressor, the refrigerating machine oil is required to be able to correspond to lubricity, especially to be able to correspond to energy saving , Efficiency.

Synthetic oils such as polyglycol oils and polyol esters, which are compatible with refrigerants, are mainly used as refrigerating machine oils for refrigeration cycles and compressors using carbon dioxide.

Specifically, in JP-A-10-46169, JP-A-2001-66004, JP-A-2001-73945, and JP-A-2001-153476, the selection of polyglycol oil and polyvinyl ether is disclosed. Lubricating oil compositions for refrigerators composed of at least one of them and having a kinematic viscosity of more than 5 mm ² /s at 100°C, and refrigeration cycles and compressors using these lubricating oil compositions for refrigerators are disclosed in JP-A-2000- Refrigerator oil compositions using polyol esters are disclosed in JP-A-273477, JP-A-2000-273479, JP-A-2000-345183, and JP-A-2001-19987.

However, in the sealed electric compressor, the performance as an electrical insulating oil is also required. Therefore, the electrical insulating performance of polyglycol oil is very low due to its molecular structure, and it cannot meet the specification value of volume resistivity exceeding 10 as an electrical insulating oil. ¹³ Ω·cm. Therefore, there is fear of short circuit between the closed terminals installed to provide external power supply to the compressor motor, especially electric shock caused by leakage current due to high dielectric constant or dielectric loss factor.

On the other hand, due to the high compatibility of polyol esters with carbon dioxide refrigerants, the solution viscosity in the compressor is greatly reduced, and the sealing performance of the high-pressure side is not good, resulting in a decrease in compression efficiency and an increase in the oil flowing out to the refrigeration cycle. May result in a decrease in heat exchange efficiency.

For the reasons described above, in a heat pump hot water supply device, a hydrocarbon oil that exhibits incompatibility with carbon dioxide and is excellent in electrical insulation is preferably used as a refrigerating machine oil. It is disclosed in JP-A No. 2000-110725 about the use of compressors with low solubility to carbon dioxide or non-compatible refrigerating machine oils. However, due to the small viscosity index of alkylbenzene, the low-temperature part of the refrigeration cycle As the viscosity increases, the amount of oil returned to the compressor decreases. Therefore, there is a danger of causing poor lubrication of the sliding part of the compressor. Fluorine oil is not realistic because of its high price.

Contents of the invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide an environment-friendly refrigeration cycle and heat pump that can ensure high reliability, save energy, and achieve high efficiency by using refrigerating machine oil that is incompatible with carbon dioxide refrigerant. Type hot water supply device.

In the refrigeration cycle and heat pump hot water supply device of the present invention, the refrigeration cycle is provided with: a compressor that sucks and compresses carbon dioxide refrigerant, a heat exchanger for releasing heat that flows into the carbon dioxide refrigerant discharged from the compressor, and The pressure reducer for reducing the pressure of the carbon dioxide refrigerant flowing out of the heat exchanger, and the heat absorbing heat exchanger for flowing the carbon dioxide refrigerant decompressed in the pressure reducer; it is characterized in that, as the compressor The refrigerating machine oil adopts any oil or mixed oil of poly-α-olefin or alkane mineral oil or naphthenic mineral oil or alkylbenzene that is incompatible with carbon dioxide refrigerant.

Another feature of the present invention is to use any of the refrigerating machine oils that are incompatible with the carbon dioxide refrigerant, have a kinematic viscosity in the range of 2 to 15 mm ² /s at 100°C, and have a viscosity index exceeding 100 for the refrigerating machine oil. An oil or a combination of oils.

Furthermore, the present invention is characterized in that the refrigerant flow path of the heat-absorbing heat exchanger has an inflow port located above and an outflow port located below.

According to the present invention, there is a compressor, a heat release heat exchanger for releasing heat from the refrigerant discharged from the compressor, a pressure reducer for decompressing the refrigerant flowing out of the heat exchanger, and In the refrigeration cycle that circulates the heat-absorbing heat exchanger that absorbs the heat of the refrigerant decompressed in the decompressor, and in the hot water supply device equipped with this refrigeration cycle, as the refrigerating machine oil of the compressor, by using carbon dioxide The refrigerant shows incompatible hydrocarbon oil, and can maintain a sufficient oil film on the sliding part of the compressor, thereby preventing abrasion and maintaining sealing performance, so that compression efficiency can be improved.

As refrigerating machine oil, it is composed of hydrocarbon oil showing incompatibility with carbon dioxide, specifically poly-α-olefin or alkane-based mineral oil or naphthenic-based mineral oil or alkylbenzene, or a mixture of these Oil. Considering the stagnation of refrigerating machine oil in the low-temperature part of the refrigeration cycle, it is preferable to use an oil with a viscosity index exceeding 100 that can easily ensure the amount of oil returned to the compressor. Other compounds showing incompatibility with carbon dioxide include fluorine oil (perfluoropolyether) and silicone oil, but these are not practical due to their high cost and poor lubricity.

Regarding the viscosity of the refrigerating machine oil used in the hot water supply device of the present invention, since the permeability of carbon dioxide is high, it should preferably be of a slightly higher viscosity grade than oil corresponding to freon refrigerants in view of sealing performance. Specifically, in a rotary refrigerant compressor, the viscosity at 100°C is preferably 2 to 8 mm ² /s, and in a scroll compressor, the viscosity at 100°C is preferably in the range of 7 to 15 mm ² /s. When the kinematic viscosity at 100° C. is lower than that, sufficient compressor wear resistance cannot be obtained, and sufficient airtightness cannot be ensured, resulting in a decrease in compression efficiency. In addition, when the dynamic viscosity at 100°C is higher than that, the efficiency of the compressor decreases due to the increase in viscous resistance and mechanical loss, and the increase in viscosity reduces the amount of oil returned to the compressor. In the present invention, there is no problem at all even if an antioxidant, an acid-reactive group regulator, an antifoaming agent, a metal inactivator, and the like are added to the aforementioned refrigerating machine oil.

Description of drawings

FIG. 1 is a schematic diagram illustrating a hot water supply device according to an embodiment of the present invention.

Fig. 2 is a longitudinal sectional view of the hot water supply device unit according to the embodiment of the present invention.

Fig. 3 is a sectional view illustrating a hermetic electric compressor according to an embodiment of the present invention.

Detailed ways

In the following, the present invention will be described in detail according to the embodiments. In this embodiment, a heat pump hot water supply device using carbon dioxide is described, but it is not limited to this, and it is also applicable to refrigeration cycles such as electric vehicle air conditioners and heating equipment in cold regions.

Fig. 1 shows a basic configuration diagram of a heat pump type hot water supply device used in this embodiment. It is divided into a refrigeration cycle in which carbon dioxide refrigerant circulates and a cycle in which supplied water is heated.

First, the refrigeration cycle is introduced. The hermetic electric compressor 1 housed in an airtight container etc. compresses low-temperature, low-pressure refrigerant gas (carbon dioxide refrigerant), and then outputs high-temperature, high-pressure refrigerant gas, which is sent to the water-refrigerant heat exchanger 2 ( exothermic heat exchanger). The heat of the refrigerant gas sent to the water-refrigerant heat exchanger 2 exchanges sensible heat with the supplied low-temperature water. Then, it passes through the pressure reducer 3, becomes low temperature and low pressure, and is sent to the heat exchanger 4 (heat exchanger for absorbing heat). The refrigerant entering the heat exchanger 4 absorbs heat from the surroundings and evaporates, and the fan 5 discharges cold air.

The low-temperature, low-pressure refrigerant gas coming out of the heat exchanger 4 is sucked into the compressor 1 again to form a mechanism that repeats the same cycle. Since the carbon dioxide refrigerant becomes a supercritical cycle, the high-pressure side exceeds the critical point, and the high-pressure pressure can be set arbitrarily, so high-temperature water close to 100°C can be easily obtained.

Next, the heating water cycle is introduced. First, the low-temperature water provided by the water supply port 6 is sent to the water-refrigerant heat exchanger 2, and the heat obtained from the refrigerant is turned into hot water, which is once sent to the hot water storage tank 7, and hot water is supplied from the hot water outlet 8. At this time, the supplied water may be mixed with hot water sent directly from the water-refrigerant heat exchanger 2 to adjust its temperature and used. And, except water supply, the water-refrigerant heat exchanger 2 can also be used for heating the hot water in the hot water storage tank 7 of keeping warm, not shown in the figure, can also be used for burning bath water etc.

In the heat pump hot water supply device, there are two ways of supplying hot water, using electricity to start the heat pump cycle at night, storing the hot water used by the family in the hot water storage tank 7 during the day, and storing hot water every time Instantaneous hot water supply method that starts the heat pump cycle even when hot water is used, and supplies only the required amount of hot water.

Even the latter method requires an auxiliary hot water storage tank 7 for storing hot water before hot water is supplied. Generally, the method of storing hot water is the mainstream. However, there are still such problems: due to the limitation of the amount of hot water used, it is impossible to store hot water in consideration of the problem of running out of hot water or the need for a large-capacity hot water storage tank. The storage tank is accommodated in the heat pump circulation unit, and a hot water storage tank unit must be provided separately, thereby increasing the installation space and the like.

On the other hand, the problem with the instantaneous water supply method is that a high-output compressor is required, and since hot water is supplied by operation at any time, there is no need to worry about running out of hot water. As an example, FIG. 2 shows a simple longitudinal sectional view of a hot water supply device unit of an instantaneous hot water supply system. The advantage is that only a small-capacity auxiliary hot water storage tank 7 is required, so the hot water storage tank can be accommodated in In the heat pump circulation unit, the space saving of the installation place is realized. In addition, since the operation time is greatly reduced compared with the hot water storage method, it also has the advantage of saving energy.

The hermetic electric compressors of hot water supply devices are mainly rotary and scroll equal volume compressors. As an example of the compression mechanism, FIG. 3 shows a longitudinal sectional view of a rotary compressor. In the single-stage compression method, when the high pressure side becomes 10MPa like carbon dioxide refrigerant, the surface pressure of the compression mechanism is very high, and the thickness of the oil film becomes thinner. As a result, the reliability is reduced, and the large differential pressure leads to the problem of low compression efficiency. Therefore, here is a two-stage compression method.

The compressor accommodates its compression part and motor 10 in an airtight container 9, and stores refrigerating machine oil 11 at the bottom of the airtight container. Also, a sealed terminal 12 for supplying external power is provided on the aforementioned motor 10 .

The compression part is rotated while the shaft 13 directly connected to the motor 10 is rotating, and a part of the rollers 14A, 14B eccentrically attached to the shaft 13 is in line contact with the inner wall of the oil 15A, 15B and bonded. . A valve separating the low-pressure chamber and the high-pressure chamber is inserted into an opening formed in the inner wall of the oil 15A, 15B, reciprocates, and is pressed toward the rollers 14A, 14B by a spring (not shown) provided at one end thereof. The low-pressure refrigerant gas sucked in through the first suction pipe 16 is compressed by the eccentric motion of the roller 14A, and discharged at an intermediate pressure through the first discharge pipe 17 . The discharged intermediate-pressure refrigerant gas is then sucked in through the second suction pipe 18, compressed due to the eccentric motion of the roller 15A, and discharged to the water refrigerant heat exchange through the second discharge pipe 19 as high-pressure refrigerant gas. Device 2. Since the friction between the valve and the rollers 14A, 14B is caused by line contact, the surface pressure is very high. The refrigerating machine oil 11 is pumped up by a centrifugal pump provided on the rotary shaft, and supplies lubricating oil to each sliding part of the compressor through the oil hole 20 .

(Embodiments 1-5)

In Examples 1 to 5, a real machine test of 2160 hours of operation was carried out using the aforementioned hot water supply device. The hot water supply device was operated indoors in a constant temperature room at 20°C in summer, and the temperature of the supplied hot water was set at a high temperature to store hot water at 60°C. In Examples, the following compounds showing incompatibility with carbon dioxide refrigerant were charged into the compressor. Compound E is a mixture of Compounds A and B at 50/50% by weight.

A) The viscosity of poly-α-olefin at 100°C is 3.59 mm ² /s

B) The viscosity of alkane mineral oil at 100°C is 4.56 mm ² /s

C) The viscosity of naphthenic mineral oil at 100°C is 4.25 mm ² /s

D) The viscosity of alkylbenzene at 100°C is 3.78mm ² /s

E) Poly-alpha-olefin + alkane mineral oil (50/50% by weight)

Viscosity at 100°C is 4.12mm ² /s

In Comparative Examples 1 and 2, the following compounds showing compatibility with the carbon dioxide refrigerant were charged in the compressor, and the same actual machine test as in Example 1 was carried out. Compared with Examples 1-5, the viscosity is increased due to the compatibility with the carbon dioxide refrigerant.

F) The viscosity of hindered polyol ester at 100°C is 10.2mm ² /s

(Pentaerythritol/Hypopentaerythritol Branched Chain Mixed Fatty Acid Ester)

G) The viscosity of polyglycol oil at 100°C is 9.7mm ² /s

(Dimethyl ether at both ends of polyethylene/polypropylene copolymer)

On the basis of ensuring the reliability of the hot water supply device, it is very important to control the friction of the compressor. Therefore, in evaluating the hot water supply device, attention should be paid to the wear state of the compressor, and the state of the roller and valve before and after the test should be checked. Also check the remaining amount of refrigeration oil in the compressor after operation. Generally speaking, when the compatibility with the refrigerant is poor, the amount of oil returned to the compressor decreases, resulting in poor lubrication of the sliding parts. Then, the hot water supply devices of Examples 1-5 were used to measure the leakage current and the COP value. Regarding the COP, the COP of Comparative Example 2 is expressed as 100%. The goal of this test is to ensure a sufficient amount of residual oil and less leakage current because there is no problem with the friction of the roller/valve, so that the COP exceeds 100% when the comparative example 2 is set to 100%. Table 1 shows the results of Examples 1-5 and Comparative Examples 1-2. In Table 1, the volume resistivity and dielectric constant of the refrigerating machine oil alone are collectively described.

Table 1 Refrigerator oil Viscosity at 100°C (mm ² /s) Roller/valve wear condition residual oil Leakage current (°C) Volume resistivity (Ω·cm) Dielectric constant COP(%) Example 1 A 3.59 no problem no problem no problem 1×10 ¹⁶ 2.2 103 2 B 4.56 no problem no problem no problem 1×10 ¹⁵ 2.3 102 3 C 4.25 no problem no problem no problem 1×10 ¹⁵ 2.2 102 4 D. 3.78 no problem no problem no problem 1×10 ¹⁵ 2.4 102 5 E. 4.12 no problem no problem no problem 1×10 ¹⁵ 2.3 102 comparative example 1 f 10.2 high friction no problem no problem 1×10 ¹⁴ 3.2 98 2 E. 9.2 slightly worn no problem Large leakage current 1×10 ¹¹ 5.5 100

It can be clearly seen from Table 1 that the hot water supply device of the present invention shown in Examples 1 to 5, compared with the hot water supply device of Comparative Examples 1 to 2, has a high reliability due to the control of friction. sex. Regarding the amount of residual oil, there is no significant difference in Comparative Examples 1 and 2 showing compatibility with carbon dioxide. Therefore, even if a refrigerating machine oil showing incompatibility is used, a sufficient oil return amount to the compressor is ensured.

The refrigeration cycle of the hot water supply device does not become low temperature like a refrigerator, so the oil is difficult to stay. This is due to the fact that the refrigerant does not dissolve in the refrigerator oil and can reduce the viscosity of the refrigerator oil. In addition, unlike the problem of leakage current in Examples 1 to 5, the hot water supply device shown in Comparative Example 2 has a very large leakage current and has a problem of electric shock. As shown together in Table 1, the volume resistivity or dielectric constant of the refrigerating machine oil varies depending on the refrigerating machine oil used, and especially the polyglycol oil shown in Comparative Example 2 has poor electrical properties.

In the hot water supply device of the present invention shown in Examples 1 to 5, since the refrigerant is not dissolved in the refrigerating machine oil, sufficient sealing performance of the compression part can be ensured, and the COP is improved compared with Comparative Example 2.

On the other hand, in Comparative Example 1, the solubility of the refrigerant in the refrigerating machine oil was high, and the solution viscosity was lowered, and sufficient sealing performance could not be ensured, and the COP was lowered. Also, in Example 5, even when a mixed oil of poly-α-olefin and paraffinic mineral oil was used, the same effect as that of a refrigerating machine oil showing incompatibility was obtained. Although a mixed oil of poly-α-olefin and paraffinic mineral oil was used in the examples, the same results could be obtained by mixing other refrigerating machine oils showing incompatibility with carbon dioxide.

(Embodiments 6-7)

Next, set the setting temperature of the hot water supply device to 7°C, which is an intermediate condition lower than that of Examples 1 to 5, and conduct the test under the same conditions as in Examples 1 to 5. state and the remaining amount of refrigerating machine oil in the compressor after operation. In this example, the following compounds showing incompatibility with carbon dioxide refrigerant and having a viscosity index exceeding 100 were charged into the compressor.

A) The viscosity of poly-α-olefin at 100°C is 3.59 mm ² /s and the viscosity index is 122

B) The viscosity of alkane mineral oil at 100°C is 4.56 mm ² /s and the viscosity index is 101

In Comparative Examples 3 and 4, the compressors were filled with the following compounds having a viscosity index of less than 100 and showing incompatibility with carbon dioxide refrigerants, and the same actual machine tests as in Examples 6 and 7 were carried out.

C) The viscosity of naphthenic mineral oil at 100°C is 4.25 mm ² /s and the viscosity index is 15

D) The viscosity of alkylbenzene at 100°C is 3.78mm ² /s and the viscosity index is less than 0

Table 2 shows the results of Examples 6-7 and Comparative Examples 3-4.

Table 2 Refrigerator oil viscosity index Roller/valve wear condition residual oil Example 6 A 122 no problem no problem 7 B 101 no problem no problem comparative example 3 C 15 slightly worn reduce 4 D. <0 high friction reduce

It can be clearly seen from Table 2 that the hot water supply device of the present invention shown in Examples 6-7 fully ensures the amount of residual oil in the compressor, controls friction and obtains high reliability. Regarding the amount of residual oil, when the viscosity index of the refrigerating machine oil exceeds 100, sufficient oil return to the compressor can be ensured.

On the other hand, in the hot water supply devices shown in Comparative Examples 3 to 4, the amount of residual oil was reduced and the frictional consumption was also increased. As for the oil return, since the most refrigerated oil stays in the low-temperature part of the refrigeration cycle, that is, from the pressure reducer 3 to the heat exchanger 4, the viscosity index of the refrigerating machine oil is large, and the viscosity increase due to low temperature is not large, ensuring the compression to the low temperature. It is beneficial to return oil to the machine.

(Embodiment 8)

Next, set the setting temperature of the hot water supply device to -5°C under winter conditions lower than those in Examples 6 to 7, and conduct the test under the same conditions as in Examples 1 to 5. state and the remaining amount of refrigerating machine oil in the compressor after operation.

In the present embodiment, the compound A) which is also effective in Embodiment 6 is charged into the compressor, and the inlet of the refrigerant flow path of the heat exchanger 4 is arranged from the upper part of the unit, and the outlet is provided at the lower part. Hot water supply unit.

In Comparative Example 5, a hot water supply device was used in which the refrigerant flow path of the heat exchanger 4 was provided with the opposite inlet from the lower part of the unit and the outlet from the upper part of the unit.

Table 3 shows the results of Example 8 and Comparative Example 5.

table 3 Refrigerator oil Heat exchanger refrigerant flow path Roller/valve wear condition residual oil Example 8 A up→down no problem no problem comparative example 5 A down→up slightly worn reduce

It can be clearly seen from Table 3 that the hot water supply device of the present invention shown in Example 8 has a large amount of residual oil, which ensures sufficient oil return to the compressor and controls friction.

On the other hand, in the hot water supply device shown in Comparative Example 5, the amount of residual oil was reduced, and the frictional consumption was also increased. As for the oil return, since the refrigerating machine oil retains the most in the low-temperature part of the refrigeration cycle, that is, from the pressure reducer 3 to the heat exchanger 4, and the heat exchanger 4 connects the refrigerant flow path from the upper part of the unit to the outlet of the refrigerant flow path. Since it is arranged in the lower part, it is obvious that oil return to the compressor becomes easy.

(Embodiments 9-11)

In Examples 9 to 11, attention was paid to the poly-α-olefin which exhibited the effect in Example 6, and the dependence of the effect on the relative viscosity change was evaluated by the same actual machine test as in Examples 6 to 7. The viscosity range used is 2.6 to 13.4 mm ² /s at 100°C. In Comparative Examples 6 to 7, refrigerating machine oils whose poly-α-olefin viscosity was outside the range of 2.0 to 15.0 mm ² /s at 100°C were used. The evaluation items were the same as in Examples 1 to 5, and the wear state of rollers and valves, the residual oil amount of refrigerating machine oil, and the COP value were measured. Regarding the COP, the COP of Comparative Example 2 is represented as 100%. Target values are as described above. Table 4 shows the results of Examples 9-11 and Comparative Examples 6-7.

Table 4 Refrigerator oil Viscosity at 100°C (mm ² /s) Roller/valve wear condition residual oil C0P(%) Example 9 A 2.6 no problem no problem 103 10 A 7.2 no problem no problem 102 11 A 13.4 no problem no problem 101 comparative example 6 A 1.5 high friction no problem 97 7 A 20.2 high friction reduce 96

It is obvious from Table 4 that in the hot water supply device of the present invention shown in Examples 9 to 11, the friction state of the roller and the valve is good, and the oil return to the compressor can be fully guaranteed, especially the oil return to the compressor can be fully ensured. The tightness of the compression part improves the COP. On the other hand, in Comparative Example 6, the viscosity of the refrigerating machine oil was too low, an insufficient oil film was formed, the friction of the rollers and valves was increased, and in particular, sufficient sealing performance could not be ensured, and the COP was lowered. In contrast, in Comparative Example 7, since the viscosity of the refrigerating machine oil was too high, it was difficult for the oil discharged into the refrigeration cycle together with the refrigerant gas to return to the compressor, so that the amount of residual oil decreased. Therefore, the amount of oil supplied to the sliding portion decreases, and friction increases. In particular, since the viscosity is too high, the viscous resistance and mechanical loss of the compressor increase, resulting in a decrease in COP.

From the results of the above examples, the hot water supply device of the present invention can fully ensure the oil return to the compressor by controlling the friction of the compressor, and can reduce the leakage current, thereby obtaining a hot water supply device with further improved COP. Although a two-stage compression rotary compressor is used in this embodiment, other scroll compressors or suspension compressors in which rollers/valves are integrated can achieve the same effect.

The main features of the present invention described above are summarized as follows.

The effect of the present invention is: a compressor that sucks and compresses the carbon dioxide refrigerant, a heat exchanger that releases heat from the refrigerant discharged from the compressor, and a pressure reducer that decompresses the refrigerant flowing out of the heat exchanger In the refrigeration cycle that circulates the refrigerant decompressed in the decompressor and the heat exchanger that absorbs heat in the decompressor, as the refrigerating machine oil of the hermetic electric compressor, the refrigerant that is incompatible with the carbon dioxide refrigerant is used. Any oil or mixed oil in poly-α-olefin or alkane mineral oil or naphthenic mineral oil or alkylbenzene, so as to obtain a heat pump hot water supply device that can control the friction of the compressor and reduce the leakage current . In addition, by setting the kinematic viscosity of the refrigerating machine oil in the range of 2 to 15 mm ² /s at 100°C, the viscosity index of the refrigerating machine oil exceeds 100, especially the refrigerant flow path on the heat exchanger where the refrigerant absorbs heat. Arranging from top to bottom can ensure the amount of oil returned to the compressor, fully maintain the tightness of the compression part, and improve the COP, so as to obtain a refrigeration cycle that does not reduce the COP that is closely related to viscous resistance or mechanical loss.

Another effect of the present invention is that, in the hot water supply device provided with the aforementioned refrigerating cycle, poly-alpha-olefin or alkane-based mineral oil showing incompatibility with carbon dioxide refrigerant is used as the refrigerating machine oil of the hermetic electric compressor. or any one of naphthenic mineral oils or alkylbenzenes or their mixed oils, so as to obtain a heat pump hot water supply device that can control the friction of the compressor and reduce the leakage current. In addition, by setting the kinematic viscosity of the refrigerating machine oil in the range of 2 to 15 mm ² /s at 100°C, the viscosity index of the refrigerating machine oil exceeds 100, especially the refrigerant flow path on the heat exchanger where the refrigerant absorbs heat. Arranging from top to bottom can ensure the amount of oil returned to the compressor, fully maintain the tightness of the compression part, and improve the COP, so as to obtain a heat pump hot water supply device that does not reduce the COP that is closely related to viscous resistance or mechanical loss.

As described above, by applying the present invention, it is possible to provide an environment-friendly refrigeration cycle and a heat pump hot water supply device that can ensure high reliability and realize energy saving and high efficiency.

Claims (4)

1. kind of refrigeration cycle, described kind of refrigeration cycle is provided with: suck and the heat absorption heat exchanger of the described carbon dioxide coolant that the compressor of compression arbon dioxide cold-producing medium, the heat release that flows into the described carbon dioxide coolant of discharging from this compressor are depressurized described pressure reducer with heat exchanger, the pressure reducer that will reduce pressure from the described carbon dioxide coolant that this heat exchanger flows out and inflow;

It is characterized in that:, adopt described carbon dioxide coolant is shown the poly-alpha-olefin of non-intermiscibility or any oil or the miscella in alkanes mineral oil or cycloalkane mineral oil or the alkylbenzene as the refrigerator oil of described compressor;

The described heat absorption refrigerant flow path of heat exchanger, its inflow entrance is positioned at top, flow export is positioned at the bottom.

2. kind of refrigeration cycle, described kind of refrigeration cycle is provided with: suck and the heat absorption heat exchanger of the described carbon dioxide coolant that the compressor of compression arbon dioxide cold-producing medium, the heat release that flows into the described carbon dioxide coolant of discharging from this compressor are depressurized described pressure reducer with heat exchanger, the pressure reducer that will reduce pressure from the described carbon dioxide coolant that this heat exchanger flows out and inflow;

It is characterized in that:, adopt described carbon dioxide coolant is shown that non-intermiscibility, kinetic viscosity are 2～15mm 100 ℃ the time as the refrigerator oil of described compressor ²The scope of/s and the viscosity index (VI) of described refrigerator oil surpass 100 any oil or miscella;

The described heat absorption refrigerant flow path of heat exchanger, its inflow entrance is positioned at top, flow export is positioned at the bottom.

3. heat-pump water heater, described heat-pump water heater possess and are provided with: suck and the compressor of compression arbon dioxide cold-producing medium, the heat release that flows into the described carbon dioxide coolant of discharging from this compressor are used the kind of refrigeration cycle of heat exchanger with heat exchanger, the pressure reducer that will reduce pressure from the described carbon dioxide coolant that this heat exchanger flows out and the heat absorption that flows into the described carbon dioxide coolant that is depressurized described pressure reducer;

It is characterized in that:, adopt described carbon dioxide coolant is shown the poly-alpha-olefin of non-intermiscibility or any oil or the miscella in alkanes mineral oil or cycloalkane mineral oil or the alkylbenzene as the refrigerator oil of described compressor;

The described heat absorption refrigerant flow path of heat exchanger, its inflow entrance is positioned at top, flow export is positioned at the bottom.

4. heat-pump water heater, described heat-pump water heater possess and are provided with: suck and the compressor of compression arbon dioxide cold-producing medium, the heat release that flows into the described carbon dioxide coolant of discharging from this compressor are used the kind of refrigeration cycle of heat exchanger with heat exchanger, the pressure reducer that will reduce pressure from the described carbon dioxide coolant that this heat exchanger flows out and the heat absorption that flows into the described carbon dioxide coolant that is depressurized described pressure reducer;

It is characterized in that:, adopt described carbon dioxide coolant is shown that non-intermiscibility, kinetic viscosity are 2～15mm 100 ℃ the time as the refrigerator oil of described compressor ²The scope of/s and the viscosity index (VI) of described refrigerator oil surpass 100 any oil or miscella;

The described heat absorption refrigerant flow path of heat exchanger, its inflow entrance is positioned at top, flow export is positioned at the bottom.

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