JPH06307725A - Air conditioner - Google Patents

Abstract

PURPOSE:To suppress lowering of thermal conduction characteristics in a heat exchanger in the case when a non-azeotropic mixture refrigerant is used, by using the non-azeotropic mixture refrigerant as a working refrigerant and by setting the sectional areas of passages of an indoor heat exchanger and an outdoor heat exchanger so that the mass flow rate of the refrigerant may show a specific value. CONSTITUTION:An air conditioner comprises an indoor heat exchanger 5, an outdoor heat exchanger 3, a compressor 1, a four-way valve 2 and an expansion mechanism 4 and the number of revolutions of the compressor 1 is controlled by a control device 100 in accordance with a state of operation of the air conditioner. In this case, a non-azeotropic mixture refrigerant is used as a working refrigerant and the sectional areas of passages of the indoor heat exchanger 5 and the outdoor heat exchanger 3 are set so that the mass flow rate of the refrigerant may show 200 to 400kg/s. Besides, sensors 101 and 102 provided at the entrance and the exit of the outdoor heat exchanger and detecting the temperature of evaporation of the refrigerant or the pressure of evaporation thereof at the time when the outdoor heat exchanger 3 operates as an evaporator, are provided, and based on the outputs thereof, the compressor 1 is controlled in the direction of increasing the number of revolutions thereof when an entrance refrigerant temperature is lower than an allowable value in comparison with an exit refrigerant temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to an air conditioner using a chlorine-free refrigerant, which has a small effect on the global environment, as a working medium.

[0002]

2. Description of the Related Art A heat pump type air conditioner uses an indoor heat exchanger as an evaporator and an outdoor heat exchanger as a condenser during cooling, and uses an indoor heat exchanger as a condenser and an outdoor heat exchanger during heating. Used as an evaporator. As the indoor / outdoor heat exchanger, for example, as disclosed in Japanese Patent Publication No. 4-47553, a plurality of fins are juxtaposed at a predetermined interval, and a plurality of heat transfer tubes as a whole are staggered so as to be orthogonal to the fins. So-called cross fin tutu formed so as to form a shape
A tube-type heat exchanger is used, and as the heat transfer tube, for example, as shown in JP-A-4-260792, an inner grooved tube whose inner surface is grooved is often used. HCFC22 (abbreviation of hydrochlorofluorocarbon), which is a single refrigerant, is used as the refrigerant, and the outer dimensions of the heat exchanger, the cross-sectional area of the refrigerant passage, etc. are set so that the HCFC22 has the highest efficiency. .

That is, since the above-mentioned prior art is an operation method for a single refrigerant HCFC22 whose boiling point does not change in the process of heat exchange, the refrigerant passage cross-sectional area is set so as to suppress the pressure loss at the rated capacity point. Has been done. For example, the refrigerant mass velocity G of an outdoor heat exchanger that operates as an evaporator during heating is relatively small, about 100 to 200 kg / s, and the pipe passage cross-sectional area per capacity is about 0.2 to 0.4 cm ² / kW. Is set to.

[0004]

In order to protect the ozone layer, which has become a problem in recent years, when a non-azeotropic mixed refrigerant is used as an alternative refrigerant to the refrigerant HCFC22 used in a conventional air conditioner, the non-azeotropic mixed refrigerant is used. As a characteristic of the refrigerant, in the condenser, first, the condensation of the refrigerant component having a high boiling point starts at the inlet side and the condensation of the refrigerant component having a low boiling point progresses toward the outlet side. Considerably lower. In the evaporator, the liquid-phase refrigerant with a large amount of low-boiling-point refrigerant components evaporates first, and the liquid refrigerant component with a high-boiling point also evaporates when heated further, so that the evaporation temperature rises toward the outlet side. Since the evaporation of the refrigerant proceeds, the evaporation temperature in the tube becomes the lowest temperature at the heat exchanger inlet.

Therefore, when the non-azeotropic mixed refrigerant is operated at the small refrigerant mass velocity as described above, the refrigerant vapor layer with a low boiling point surrounds the condensed liquid film with a high boiling point in the condensation process in the heat transfer tube. Then, it develops along the wall surface and the condensing heat transfer coefficient decreases remarkably. Also, in the evaporation process,
Since the refrigerant vapor layer having a high boiling point develops along the wall surface so as to surround the boiling liquid film having a low boiling point, the boiling heat transfer coefficient also remarkably decreases.

That is, the above-mentioned prior art is concerned with a problem peculiar to the non-azeotropic mixed refrigerant that the heat transfer characteristic is deteriorated due to the development of the vapor layer which inhibits the heat transfer generated along the wall surface due to the deviation of the components in the condensation and evaporation processes. Is not considered. Further, in the non-azeotropic mixed refrigerant, the evaporation temperature rises along the refrigerant flow direction, so the evaporation temperature at the heat exchanger inlet is particularly low, and the outdoor heat exchanger tends to locally frost during heating operation. Since no consideration is given to the problem, the heat transfer performance of the heat exchanger is remarkably reduced and the cooling capacity and heating capacity of the heat pump type air conditioner cannot be exhibited if the conventional operation method using the single refrigerant HCFC22 is used as it is. was there.

A first object of the present invention is to provide an air conditioner capable of suppressing deterioration of heat transfer characteristics of a heat exchanger even when a non-azeotropic mixed refrigerant is used as a substitute refrigerant for the HCFC 22.

A second object of the present invention is to provide an air conditioner capable of exerting heating capacity at low outside air temperature.

A third object of the present invention is to provide an air conditioner capable of preventing the non-azeotropic mixed refrigerant from being operated while its performance is deteriorated due to a large deviation of the mixing ratio.

[0010]

In order to achieve the above first object, the air conditioner of the present invention is an air conditioner comprising an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, and an expansion mechanism. In the machine, a non-azeotropic mixed refrigerant is used as a working medium, and the passage cross-sectional areas of the indoor heat exchanger and the outdoor heat exchanger are set such that the mass flow rate of the refrigerant is 200 to 400 kg / s. It is a thing.

Further, it comprises an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve and an expansion mechanism, and is provided with a control device for controlling the number of revolutions of the compressor, and a non-azeotropic mixed refrigerant is used as a working refrigerant. In the air conditioner, the outdoor heat exchanger and the indoor heat exchanger are composed of heat transfer fins and heat transfer tubes that are inner surface processing tubes, and the outdoor heat exchanger has a rated capacity when acting as an evaporator. The mass velocity of the refrigerant is 200 to 400 kg /
The number of revolutions of the compressor is controlled by the control device so as to be s.

Further, it comprises an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve and an expansion mechanism, and is equipped with a control device for controlling the rotation speed of the compressor, and uses a non-azeotropic mixed refrigerant as a working medium. In the air conditioner, the indoor heat exchanger and the outdoor heat exchanger are composed of heat transfer fins and heat transfer tubes that are inner surface processing tubes, and the rated capacity when the outdoor heat exchanger acts as an evaporator The cross-sectional area of the refrigerant passage is 0.1 to 0.21
It is characterized in that the tube diameter and the number of passes are selected so that it becomes cm ² / kW.

In order to achieve the second object, the air conditioner of the present invention is an air conditioner comprising an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, and an expansion mechanism, as a working medium. Using a non-azeotropic mixed refrigerant, a sensor for detecting the refrigerant temperature at the inlet side and the outlet side of the outdoor heat exchanger, and a control device for controlling the rotational speed of the compressor by inputting the output of the sensor It is characterized by having.

Further, it comprises an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve and an expansion mechanism, and is equipped with a control device for controlling the number of revolutions of the compressor, and uses a non-azeotropic mixed refrigerant as a working medium. In the above air conditioner, a refrigerant temperature detecting sensor is provided on the inlet side and the outlet side of the outdoor heat exchanger, and when the outdoor heat exchanger detected by the refrigerant temperature detecting sensor acts as an evaporator. The inlet and outlet refrigerant temperatures in the heat exchanger are input to the controller, and the controller controls the compressor rotation speed to control the inlet and outlet temperatures of the outdoor heat exchanger. is there.

Further, it comprises an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve and an expansion mechanism, and is equipped with a control device for controlling the number of revolutions of the compressor, and uses a non-azeotropic mixed refrigerant as a working medium. In the air conditioner, the outdoor heat exchanger is provided with a refrigerant temperature detecting sensor on the inlet side and the outlet side of the outdoor heat exchanger, and the outdoor heat exchanger is detected by the refrigerant temperature detecting sensor and acts as an evaporator. When it is determined that the inlet side refrigerant temperature is lower than the outlet side refrigerant temperature than the allowable value, the control device controls the compressor rotational speed to increase.

The cross-sectional area of the refrigerant passage of the indoor heat exchanger is set to be smaller than the cross-sectional area of the refrigerant passage of the outdoor heat exchanger. Further, the outdoor heat exchanger and the indoor heat exchanger are provided with slits in the middle part.

In order to achieve the third object, the air conditioner of the present invention comprises an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve and an expansion mechanism, and controls the rotation speed of the compressor. An air conditioner equipped with a control device for controlling and using a non-azeotropic mixed refrigerant as a working medium, comprising a sensor for detecting a refrigerant evaporation temperature on the outlet side of the outdoor heat exchanger, which is detected by the sensor. When it is determined that the refrigerant temperature is higher than the allowable value of the outlet side superheat amount of the heat exchanger when acting as an evaporator, a refrigerant leakage alarm is output.

[0018]

In order to achieve the first object, the air conditioner of the present invention has a refrigerant mass flow rate of 200 to 400 kg as described above.
The passage cross-sectional areas of the indoor heat exchanger and the outdoor heat exchanger are set to be / s. Since the compressor rotation speed is increased to increase the refrigerant circulation flow rate, the refrigerant mass velocity in the pipe is 200 to 40.
It becomes as high as 0 kg / s, and as a result of promoting the mixing of the heat transfer impeding vapor layer formed along the wall surface with the main flow due to the uneven distribution of components in the condensation and evaporation processes peculiar to non-azeotropic refrigerants, the heat transfer characteristics The decrease is suppressed, the heat exchange efficiency is improved, and the performance of the air conditioner can be significantly improved.

In order to achieve the second object, since the air conditioner of the present invention is constructed as described above, the heating in which the outdoor heat exchanger acts as an evaporator due to the increase of the mass velocity of the refrigerant. Since the evaporation pressure loss increases during operation,
The heat exchanger inlet pressure rises and the evaporation temperature rises, and the temperature difference between the heat exchanger surface and the air temperature decreases. As a result, the frost formation amount based on the temperature difference can be suppressed at a low outdoor temperature, so that the heating performance of the air conditioner using the non-azeotropic mixed refrigerant at a low outdoor temperature can be significantly improved.

In order to achieve the third object, the air conditioner of the present invention is constructed as described above, so that even if the refrigerant leaks and the mixing ratio of the non-azeotropic mixed refrigerant greatly deviates, −
It can be detected based on the amount of part heat, and by warning or displaying this, it is possible to prevent an operation with a large deterioration in performance.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a side view of an outdoor heat exchanger, FIG. 3 is a side view of an indoor heat exchanger 5, and FIG. 4 is a pipe interior. FIG. 5 is a diagram showing changes in the condensation heat transfer coefficient when the mass velocity of the flowing refrigerant is changed, and FIG. 5 is a diagram schematically showing changes in the state of the refrigerant circulating in the refrigeration cycle on the TS diagram.

As shown in FIG. 1, the refrigeration cycle includes a refrigerant compressor 1 equipped with a compressor driven by an inverter, a four-way valve 2,
The outdoor heat exchanger 3, the pressure reducer 4, and the indoor heat exchanger 5 are connected by a refrigerant pipe so that the refrigerant circulates inside. The refrigerant compressor 1 includes, for example, D contained in a chamber.
It is driven by a variable speed motor 1a such as a C brushless motor. The flow direction of the refrigerant during heating operation is indicated by the broken arrow 1.
9 (the direction of the refrigerant flow during the cooling operation is indicated by a solid arrow 18), the temperature sensor 101 is located at the refrigerant inlet position of the outdoor heat exchanger 3 at that time, and the temperature sensor 102 is located at the refrigerant outlet position. Outdoor unit 2
In 00, a temperature sensor 103 for detecting the outside air temperature is provided. These temperature sensors 101, 102,
The output of 103 is input to the control device 100, and the control device 100 is configured to perform feedback control of the rotation speed of the compressor 1. The temperature sensor 1
A pressure sensor (not shown) may be provided instead of 01 and 102, and the detected pressure value may be converted into a refrigerant physical property value to obtain the temperature.

The outdoor heat exchanger 3 has the structure shown in FIG. In FIG. 2, an arrow 20 indicates the passage direction of air with respect to the heat exchanger 3. Reference numeral 8 denotes a plurality of heat transfer fins juxtaposed at predetermined intervals. The heat transfer fin 8 is provided with a slit 80 at a middle portion thereof as shown in FIG. A row of circular holes for inserting the heat tubes is drilled along the longitudinal direction. 9 is this heat transfer fin 8
A refrigerant pipe through which the refrigerant flows inside the circular hole inserted and joined at a right angle to 10 is a bend connecting the refrigerant pipes.
Two groups of U-shaped refrigerant circuits are vertically configured by the group of heat transfer tubes 9 connected by 0, and Y-shaped refrigerant diverters 12 provided at the inlet and outlet of the heat exchanger 3 respectively Split the refrigerant in the circuit.

The indoor heat exchanger 5 has a structure shown in FIG. In FIG. 3, the arrow 21 indicates the passage direction of air to the heat exchanger 5. 3 that are the same as those in FIG. 2 are the same as those in FIG. 2 and will not be described. A T-shaped refrigerant distributor 1 for distributing the refrigerant is provided in the middle of the heat exchanger 5.
1 is arranged, and two U-shaped refrigerant circuits are vertically arranged inside the heat exchanger via the T-shaped refrigerant distributor 11. In addition, the heat transfer tube of the outdoor heat exchanger is usually thicker than the indoor heat transfer tube.

In the indoor heat exchanger 5 and the outdoor heat exchanger 3, the refrigerant passage cross-sectional area in which the two circuits are combined is such that when the compressor speed is set to the rated capacity speed, the pipe refrigerant mass speed G
Is relatively large, for example, G = 200 to 400 kg / s, and the pressure loss of the refrigerant passage when acting as an evaporator is such that the increase in evaporation temperature between the inlet and outlet of the heat exchanger shown in FIG. 2 is canceled out. The number of passes and the inner diameter of the heat transfer tube are set so that this condition can be satisfied.

The reason for setting the number of passes and the inner diameter of the heat transfer tube in this way is as follows. FIG. 4 shows changes in the condensation heat transfer coefficient when the mass velocity of the refrigerant flowing in the pipe is changed. In FIG. 4, HFC32 (abbreviation of hydrofluorocarbon 22) and HFC134a are used as a single refrigerant, and HFC32 and HFC134a are mixed as a non-azeotropic mixed refrigerant at a mass fraction of 30/70 wt%. The case where an azeotropic mixed refrigerant (HFC32 / HFC134a) is used is shown. In the case of a smooth tube, the condensation heat transfer coefficient of the single refrigerant HFC134a decreases as the mass velocity G decreases as shown in FIG. 4, and becomes almost constant when the mass velocity becomes 200 kg / s or less. In the case of a non-azeotropic mixed refrigerant, a linear decrease is recognized.

On the other hand, in the case of the grooved tube, the single refrigerant H
The condensation heat transfer coefficients of FC32 and HFC134a are almost constant regardless of the mass velocity, whereas the condensation heat transfer coefficient of the non-azeotropic mixed refrigerant decreases as the mass velocity decreases. As a result, a significant decrease is seen.

As described above, the heat transfer coefficient of the non-azeotropic mixed refrigerant is greatly reduced as compared with the case of a single refrigerant, especially at a small mass velocity, because the non-azeotropic mixed refrigerant has a high boiling point in the condensation process. This is because the low-boiling-point refrigerant vapor layer that surrounds the condensed liquid film develops in the center of the tube, and the condensation heat transfer coefficient decreases significantly, which is high by increasing the mass velocity and disturbing the flow in the tube. It shows that the heat transfer coefficient can be obtained.

From the results shown in FIG. 4, in the case of the conventional single refrigerant, even if the mass velocity is 200 kg / s or less, the decrease in the heat transfer coefficient is slight, and rather, by setting the mass velocity smaller than this. Since the pressure loss is suppressed and the heat exchange efficiency is improved, the conventional mass velocity is about 200 kg.
The cross-sectional area of the refrigerant passage is set so as to be not more than / s.

However, in the case of a non-azeotropic mixed refrigerant, unlike the conventional single refrigerant, when the mass velocity is reduced, the heat transfer coefficient is significantly reduced, and therefore the heat exchange efficiency is also reduced. In order to improve the heat exchange efficiency, it is necessary to set the mass velocity larger than the mass velocity (roughly 200 kg / s or less) in an air conditioner using a conventional single refrigerant. However, while increasing the mass velocity of the refrigerant improves the heat transfer coefficient,
Since the pressure loss increases and adverse effects occur, approximately 400 kg
/ S is the upper limit, and in this embodiment, 200 to 400 kg /
It is preferable to set to s.

Next, the operation of the air conditioner of the present embodiment constructed as above will be described. First, the case of the cooling operation will be described. During the cooling operation, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 is sent to the outdoor heat exchanger 3 acting as a condenser through the four-way valve 2 as shown by the solid arrow 18, and is then discharged by the outdoor fan 6. It is cooled by the blown air to become high-pressure and low-temperature refrigerant, and the pressure reducer 4
Is adiabatically expanded into a low-pressure and low-temperature refrigerant, flows into the indoor heat exchanger 5 that acts as an evaporator, is heated by the air blown by the indoor fan 7 and evaporates, and then is compressed through the four-way valve 2. It returns to the machine 1 and is compressed again and circulated. At this time, the cooled air is discharged into the room for cooling.

In the cooling operation, the high-temperature and high-pressure gas refrigerant 18 discharged from the compressor 1 flows into the outdoor heat exchanger through the inlet pipe 16. The refrigerant that has flowed into the outdoor heat exchanger is divided into two upper and lower U-shaped refrigerant circuits via the Y-shaped refrigerant distributor 12. At this time, unlike the single refrigerant, when the non-azeotropic mixed refrigerant in the condenser is cooled to the dew point temperature determined by the mixing ratio, condensation of the refrigerant component with a high boiling point begins, and the boiling point decreases as the condensation progresses. The condensation ratio of the refrigerant components increases, and finally the liquid components are cooled to the liquidus temperature determined by the mixing ratio and all are condensed. Therefore, the refrigerant condensing temperature in the heat transfer tube forming the U-shaped refrigerant circuit drops considerably while passing through the heat transfer tube. Therefore, a temperature difference occurs between the windward side heat transfer tube and the leeward side heat transfer tube that sandwich the slit 80, but the windward half portion and the leeward side half portion of the heat transfer fin are thermally separated by the slit 80. Therefore, it is possible to prevent an unnecessary heat transfer phenomenon in both heat transfer tubes from occurring via the fins, so that the heat exchange performance as the condenser is improved.

The condensed and liquefied refrigerant expands through the pressure reducer 4 and becomes a low-temperature low-pressure atomized gas-liquid two-phase refrigerant and flows into the indoor heat exchanger 5 which functions as an evaporator. The refrigerant in the gas-liquid two-phase state that has flowed in from the refrigerant inlet pipe 11 arranged in the center of the indoor heat exchanger is provided in the heat exchanger.
The flow is split into two in the upper and lower directions via the V-shaped flow distributor 11, and flows into the heat transfer tube group forming the U-shaped refrigerant circuit. In the indoor heat exchanger that acts as an evaporator, unlike a single refrigerant, the liquid-phase refrigerant with many low-boiling-point refrigerant components evaporates, and when heated, the liquid-boiling refrigerant component with high-boiling point also evaporates. When heated to the dew point temperature determined by the mixing ratio, the refrigerant in the vapor phase is entirely formed.

As described above, the non-azeotropic mixed refrigerant, unlike the single refrigerant, causes the components to be biased in the process of condensation or evaporation, so that the conventional indoor / outdoor heat exchange in which the mass velocity is set to be relatively small. In the vessel, the heat transfer coefficient will be greatly reduced.

Further, as shown by the alternate long and short dash line in FIG. 5, the evaporation temperature of the refrigerant rises considerably between the indoor heat exchanger inlet and outlet (indicated by CD in FIG. 5) which functions as an evaporator. Figure 5
The change of the state of the refrigerant circulating in the refrigeration cycle is shown.
In FIG. 5, the horizontal axis represents the entropy S of the refrigerant, and the vertical axis represents the temperature T.
Is shown. Here, Tc is the condensation temperature corresponding to the internal pressure of the condenser, and Te is the evaporation temperature corresponding to the internal pressure of the evaporator. Further, A and B respectively indicate the inlet and outlet of the heat exchanger acting as a condenser, and C and D respectively indicate the inlet and outlet of the heat exchanger acting as an evaporator. The broken line and the alternate long and short dash line in FIG. 5 show changes in the state of the refrigerant in the conventional air conditioner, the dashed line indicates the case of using the single refrigerant HCFC22, and the alternate long and short dashed line indicates the case of using the non-azeotropic mixed refrigerant. is there. The case of the air conditioner using the non-azeotropic mixed refrigerant of the present embodiment is shown by the solid line.

As described above, in the indoor heat exchanger 5 of this embodiment, the cross-sectional area of the refrigerant passage is set so that the in-pipe refrigerant mass velocity G is relatively large, for example, G = 200 to 400 kg / s. Therefore, as can be seen from FIG. 4, a high heat transfer coefficient is obtained, the cycle efficiency is improved, and the refrigerant passage pressure loss when acting as an evaporator is set so that the refrigerant mass velocity G is 200 kg / s or less. It is larger than the conventional heat exchanger. As a result, the evaporator inlet temperature rises and the inlet evaporation temperature rises, as shown by the solid line in FIG.
The evaporation temperature of the refrigerant is almost constant between the inlet and outlet of the heat exchanger (indicated by CD in FIG. 5). Therefore, the distribution of the exhaled air temperature during cooling is uniform, and there are no problems such as dew condensation on the blowout grill of the indoor unit or splashing of water drops.

Next, the operation during the heating operation will be described.
During heating, the four-way valve 2 is switched so that the flow direction of the refrigerant is opposite to that in the cooling operation, as shown in Fig. 1. Contrary to the cooling operation, the indoor heat exchanger serves as a condenser and the outdoor heat exchanger evaporates. Acts as a container. That is, during the heating operation, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 is sent to the indoor heat exchanger 5 acting as a condenser through the four-way valve 2 as shown by a dashed arrow 19, and the indoor fan 7 Is cooled by the air blown by the air to become a high-pressure, low-temperature refrigerant, adiabatically expanded by the pressure reducer 4 and becomes a low-pressure, low-temperature refrigerant, which flows into the outdoor heat exchanger 3 acting as an evaporator, and is then cooled by the outdoor fan 6. After being heated by the blown air and evaporated, it returns to the compressor 1 through the four-way valve 2 and is compressed again and circulated. At this time, the heated air is released into the room for heating.

The high-temperature and high-pressure gas refrigerant 19 discharged from the compressor 1 flows into the indoor heat exchanger 5 through the inlet pipe 14. The refrigerant that has flowed into the indoor heat exchanger splits in the upper and lower two U-shaped refrigerant circuits via the Y-shaped refrigerant distributor 12. When the non-azeotropic mixed refrigerant in the refrigerant circuit is cooled to the dew point temperature determined by the mixing ratio by exchanging heat with the room air, condensation with a large amount of refrigerant component having a high boiling point starts. As the condensation proceeds, the rate of condensation of the refrigerant component having a low boiling point increases, and finally, the refrigerant is cooled to the liquidus temperature determined by the mixing ratio and all is condensed. Therefore, the refrigerant condensing temperature in the heat transfer tube forming the U-shaped refrigerant circuit drops considerably while passing through the heat transfer tube. Therefore, similar to the outdoor heat exchanger during the cooling operation, a temperature difference occurs between the windward heat transfer tube and the leeward heat transfer tube that sandwich the slit 80. However, the windward half and the leeward half of the heat transfer fins are generated. Slit the part 80
Since it is configured to be thermally separated by the above, it is possible to prevent an unnecessary heat transfer phenomenon in both heat transfer tubes via the fins, and improve the heat exchange performance as the condenser. The refrigerant condensed through the two U-shaped refrigerant circuits merges again through the T-shaped refrigerant distributor 11 to increase the mass velocity and is further cooled in the heat transfer tube to become a supercooled liquid refrigerant. Flows out from the outlet pipe 13. in this way,
The heat transfer coefficient in the tube is improved by the merging and the increase of the mass velocity, so that the heat exchange performance as the condenser is further improved.

The liquid refrigerant exiting the indoor heat exchanger expands through the pressure reducer 4 to become a low-temperature low-pressure atomized refrigerant in a gas-liquid two-phase state to the outdoor heat exchanger 5 acting as an evaporator. Inflow. Refrigerant inlet pipe 1 arranged in the central part of the outdoor heat exchanger
The gas-liquid two-phase refrigerant that has flowed in from 7 is divided into two upper and lower U-shaped refrigerant circuits via the Y-shaped refrigerant distributor 12. At this time, in the outdoor heat exchanger that acts as an evaporator, the refrigerant in the liquid phase having a large amount of the refrigerant component with a low boiling point evaporates initially by heating with air, and when further heated, the liquid refrigerant component with a high boiling point also evaporates. Then, when heated to the dew point temperature determined by the mixing ratio, all become the vapor phase refrigerant.

In the heating operation as well, the heat transfer mechanism of condensation and evaporation in the tube, in which the components are biased in the process of condensation or evaporation, does not change, so the mass velocity is relatively small, and G = 200 kg / s or less. In the conventional indoor and outdoor heat exchangers that have been set, the heat transfer coefficient is significantly reduced. Further, as shown by the alternate long and short dash line in FIG. 5, the outdoor heat exchanger acting as an evaporator has the lowest evaporation temperature at the inlet portion, and the evaporation temperature rises toward the outlet.
As described above, the indoor heat exchanger 5 and the outdoor heat exchanger 3 of this embodiment have a relatively large in-pipe refrigerant mass velocity G, for example, G
= 200 to 400 kg / s, the refrigerant passage cross-sectional area is set to obtain a high heat transfer coefficient as shown in FIG. Performance is greatly improved.

In order to satisfy the above refrigerant mass velocity G,
Refrigerant passage cross-sectional area As (m) of the indoor heat exchanger and the outdoor heat exchanger
² ) is the rated capacity Q (kW) and mass velocity G as follows.
It can be set by using the following equation which is a relational expression with.

Q = As × G × γ × (1 + C) (1) where γ (J / kg) is the latent heat of the refrigerant, and C is the ratio of the sensible heat change component of the refrigerant at the inlet and outlet of the condenser to the latent heat. The value of the constant C is usually 0.3 to 0.4. The value of latent heat γ is about 160 kJ / kg in the case of the conventional refrigerant HCFC22, and about 180 kJ / kg in the case of a non-azeotropic mixed refrigerant obtained by mixing two or three kinds of refrigerants such as HFC32, HFC134a, and HFC125. Therefore, in this embodiment, it is preferable to set the refrigerant passage cross-sectional area As / Q per rated capacity as follows. That is, 1 / (400
× 180 × 1.4) to 1 / (200 × 180 × 1.3)
It is preferable to set it in the range of 0.1 to 2.14 (cm ² / kW).

The outdoor heat exchanger 3 acting as an evaporator is
The refrigerant passage pressure loss is larger than in the conventional case, and the evaporator inlet pressure rises and the evaporation temperature also rises, so that the increase in the evaporation temperature along the refrigerant flow direction is canceled out. As a result, as shown by the solid line in FIG. 5, the refrigerant evaporation temperature Te between the outdoor heat exchanger inlet and outlet (indicated by CD in FIG. 5) becomes substantially constant. Refrigerant evaporation temperature T
Since e is almost constant, the fin temperature during heating is also almost uniform over the entire heat exchanger, and the heating capacity is abruptly increased due to clogging caused by frost that is unevenly distributed in low temperature areas as in the past. It does not cause problems such as a decrease in

In this embodiment, the indoor heat exchanger is
The operating pressure when operating as an evaporator is higher than that of an outdoor heat exchanger, and the critical mass velocity for pressure loss is also high, so the passage cross-sectional area of the indoor heat exchanger may be set small as the refrigerant passage cross-sectional area. .

Further, in the present embodiment, at least when the rated capacity is generated, the capacity deterioration due to frost formation, the capacity deterioration due to the decrease of the heat transfer coefficient in the pipe, etc. are prevented so that the efficient operation can be performed.
It suffices that a relatively large in-tube refrigerant mass velocity can be secured by setting the passage cross-sectional area of the heat exchanger and the rotation speed of the compressor, and the rotation speed of the compressor may be constant during operation.

The second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram showing a flowchart of the operation control method according to this embodiment.

Also in this embodiment, the cycle structure, the indoor heat exchanger and the outdoor heat exchanger are the same as those of the embodiment shown in FIGS. 1 to 3, but in this embodiment, the evaporator is used during the heating operation. Refrigerant inlet temperature Tc of the acting outdoor heat exchanger 3
1. The refrigerant circulation flow rate is controlled so that the outlet temperature Tc2 is approximately the same.

In this embodiment, the operation control method is performed as follows. The refrigerant inlet temperature Tc1 and the outlet temperature Tc2 of the outdoor heat exchanger 3 are measured using the temperature sensors 101 and 102. As the temperature sensors 101 and 102, for example, thermistor temperature sensors are used, and the refrigerant outlet temperature Tc2
So that the compressor suction refrigerant temperature is almost saturated temperature,
By controlling the opening degree of the expansion valve 4 via a controller (not shown), the temperature is maintained substantially at the saturation temperature. The refrigerant inlet temperature Tc1 measured in this way is equal to the outlet temperature Tc2.
If it is lower than the allowable value of, the inverter control device 100 shown in FIG.
To increase the refrigerant circulation flow rate.

By controlling in this way, the mass velocity of the refrigerant increases and the pressure loss increases, so that the rise in the evaporation temperature along the flow direction of the refrigerant is canceled out. In addition, the increase in the mass velocity of the refrigerant improves the heat transfer coefficient in the pipe and makes the temperature of the heat exchanger almost uniform over the entire surface, suppressing frost formation at low outside temperatures and significantly improving the heating capacity. To do. In this embodiment, the refrigerant outlet temperature Tc2 is indirectly controlled via the compressor intake refrigerant temperature, but the refrigerant outlet temperature Tc2 may be directly controlled.

A third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing a flowchart that is the operation control method according to the present embodiment.

In the second embodiment, the refrigerant inlet temperature and the outlet are controlled to be substantially equal to each other regardless of the heating load, whereas in the present embodiment, the outside air temperature is detected and the outside air temperature is The refrigerant circulation flow rate is controlled by changing the number of revolutions of the compressor so that the heating capacity can be exhibited when the heating load is large at approximately 5 ° C. or less.

The outside air temperature is detected by using the outside air temperature sensor 103 arranged around the outdoor heat exchanger 3. At this time,
The temperature difference between the outside air temperature and the evaporation temperature is usually 7 to 10 ° C, and when the outside air temperature drops to 5 to 6 ° C or less, the fin surface temperature also becomes 0 ° C or less and the moisture in the air becomes frost on the fin surface. Will become attached. However, when a non-azeotropic mixed refrigerant is used, even if the fin surface temperature is 0 ° C. on average, in the conventional operation method, the temperature at the inlet of the heat exchanger is increased due to the temperature gradient along the refrigerant flow direction. Below 0 ° C,
There has been a problem that frost is locally formed and performance is deteriorated. On the other hand, in this embodiment, as shown in FIG. 7, the outside air temperature To is measured using the outside air temperature sensor 103 provided around the outdoor heat exchanger 3. When the outside air temperature To becomes 5 ° C. or lower, the refrigerant inlet temperature Tc1 and the outlet temperature Tc2 of the outdoor heat exchanger 3 are further measured. The inverter control circuit 1 shown in FIG. 1 is configured so that the refrigerant inlet temperature Tc1 and the outlet temperature Tc2 measured in this manner are approximately equal.
00, a signal is sent to the variable rotation speed motor to increase the rotation speed of the compressor 1 to increase the refrigerant circulation flow rate.

By the above control, when the outside air temperature decreases to 5 ° C. or less and the heating load increases, the mass velocity of the refrigerant increases, and a pressure loss occurs so that the increase in the evaporation temperature along the refrigerant flow direction is canceled out. As a result, the heat transfer coefficient in the pipe is improved, the temperature of the heat exchanger is made almost uniform as a whole, and the frost formation at low outside air temperature is suppressed and the heating capacity is greatly improved.

In the above-mentioned embodiment, the number of revolutions of the compressor is controlled so that the vaporization temperatures at the inlet and outlet of the heat exchanger are substantially equal, but the temperature sensor and the pressure sensor provided at the outlet of the heat exchanger are used. It may be used to detect refrigerant leakage. In this case, as shown in FIG. 1, a temperature sensor 101 is provided at the refrigerant inlet position, a temperature sensor 102 is provided at the refrigerant outlet position, and a pressure sensor (not shown) is provided at the outlet. During normal operation, the outlet pressure of the heat exchanger is detected by a pressure sensor, and the saturation temperature of the refrigerant is calculated by converting from that pressure. Next, as a temperature difference from the refrigerant temperature detected by the temperature sensor 102, the superheater at the outlet of the heat exchanger is used.
The control amount is calculated by the control circuit. This requested super heat
If the charge amount is larger than a predetermined value, it is determined that the refrigerant has leaked, and the control circuit generates an alarm signal or a signal for displaying and issues an alarm or display.

By doing so, it is possible to prevent the operation of the air conditioner, which greatly deviates from the proper mixing ratio of the refrigerant, and to prevent the operation of the air conditioner while the performance is deteriorated.

As described above, the refrigerant passage sectional areas of the indoor heat exchanger and the outdoor heat exchanger have a relatively large in-tube refrigerant mass velocity G when the compressor rotation speed is set to the rated capacity generation rotation speed, For example, since G is set to about 200 to 400 kg / s, it is possible to prevent a large decrease in heat transfer coefficient due to uneven distribution of the refrigerant components in the process of condensation or evaporation. Further, since the pressure loss of the refrigerant passage when acting as an evaporator is set so as to cancel out the boiling point rise between the heat exchanger inlet and outlet, the evaporation temperature of the refrigerant becomes substantially constant between the heat exchanger inlet and outlet.

Therefore, the distribution of the exhaled air temperature during cooling becomes uniform, and the dew on the blowout grill of the indoor unit, etc.
The performance of a heat pump type air conditioner that has a refrigeration cycle for non-azeotropic mixed refrigerant does not occur because it does not cause problems such as water droplets popping out or the problem of localized frost formation on the outdoor heat exchanger at low outdoor temperatures. Remarkably improved.

As can be seen from FIG. 4, the performance change of the non-azeotropic mixed refrigerant occurs in the smooth pipe and the grooved pipe in the same manner. Therefore, even if the smooth pipe is used, the inner surface processing including the grooved pipe is processed. It is possible to exert the same effect as that achieved in the tube.

[0059]

As described above, according to the present invention,
The refrigerant passage cross-sectional areas of the indoor heat exchanger and the outdoor heat exchanger have a relatively large in-pipe refrigerant mass velocity G when the compressor rotation speed is set to the rated capacity generation rotation speed, for example, G = 200 to 50.
Since it is set to be about 0 kg / s, it is possible to prevent a large decrease in the heat transfer coefficient due to the imbalance of the refrigerant components in the process of condensation or evaporation.

Further, since the pressure loss of the refrigerant passage when acting as an evaporator is set so as to cancel out the boiling point rise between the heat exchanger inlet and outlet, the evaporation temperature of the refrigerant is substantially constant between the heat exchanger inlet and outlet. Becomes Therefore, the distribution of the exhaled air temperature during cooling will be uniform, and there will be problems such as dew on the blowout grill of the indoor unit, splashes of water droplets, and local frost formation on the outdoor heat exchanger at low outdoor temperatures. Since no problem occurs, the performance of the heat pump type air conditioner having the refrigeration cycle for non-azeotropic mixed refrigerant is significantly improved.

Further, even when the refrigerant leaks, it is possible to prevent the operation with the mixing ratio of the non-azeotropic mixed refrigerant largely deviated.

[0062]

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner that is an embodiment of the present invention.

FIG. 2 is a side view of the outdoor heat exchanger.

FIG. 3 is a side view of the indoor heat exchanger.

FIG. 4 is a diagram showing a result of a condensation heat transfer experiment of an inner grooved tube and a smooth tube which constitute a refrigeration cycle.

FIG. 5 is a refrigeration cycle TS diagram of the air conditioner.

FIG. 6 is a diagram showing a flowchart of operation control which is a second embodiment of the present invention.

FIG. 7 is a diagram showing a flowchart of operation control according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 1a ... Variable speed motor, 3 ... Outdoor heat exchanger, 4 ... Decompressor, 5 ... Indoor heat exchanger, 8 ... Heat transfer fin, 9 ... Inner grooved heat transfer tube, 18 ... Cooling , An arrow indicating the refrigerant flow direction of 19 ... An arrow indicating the refrigerant flow direction during heating,
80 ... Slit part, 100 ... Inverter control device, 10
1, 102, 103 ... Temperature sensor, 200 ... Indoor unit, 201 ... Outdoor unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Fukushima 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Hiritsu Works Co., Ltd. Mechanical Research Laboratory (72) Hiroshi Kogure 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Hitachi, Ltd. (72) Inventor, Hiroaki Matsushima, 502, Kamidate-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd.

Claims (10)

[Claims] 1. An air conditioner comprising an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, and an expansion mechanism, which uses a non-azeotropic mixed refrigerant as a working medium and has a refrigerant mass flow rate of 200 to 400 kg /. An air conditioner in which the passage cross-sectional areas of the indoor heat exchanger and the outdoor heat exchanger are set to be s. 2. An air conditioner comprising an indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve and an expansion mechanism, wherein a non-azeotropic mixed refrigerant is used as a working medium and the inlet side of the outdoor heat exchanger is used. An air conditioner comprising: a sensor for detecting the temperature of the refrigerant on the outlet side; and a control device for inputting the output of the sensor to control the rotation speed of the compressor. 3. An indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, an expansion mechanism, a control device for controlling the rotation speed of the compressor, and a non-azeotropic mixed refrigerant as a working medium. In the above air conditioner, a refrigerant temperature detecting sensor is provided on the inlet side and the outlet side of the outdoor heat exchanger, and when the outdoor heat exchanger detected by the refrigerant temperature detecting sensor acts as an evaporator. An air conditioner characterized by inputting refrigerant temperatures at an inlet and an outlet in a heat exchanger to the control device, and controlling the compressor rotation speed by the control device to control the inlet and outlet temperatures of the outdoor heat exchanger. Machine. 4. An indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, an expansion mechanism, a control device for controlling the rotation speed of the compressor, and a non-azeotropic mixed refrigerant as a working medium. In the air conditioner, the outdoor heat exchanger is provided with a refrigerant temperature detecting sensor on the inlet side and the outlet side of the outdoor heat exchanger, and the outdoor heat exchanger is detected by the refrigerant temperature detecting sensor and acts as an evaporator. The air conditioner is characterized in that, when it is determined that the inlet side refrigerant temperature of is lower than the allowable value as compared with the outlet side refrigerant temperature, the control device controls in a direction of increasing the compressor rotation speed. 5. An indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, an expansion mechanism, a control device for controlling the number of revolutions of the compressor, and a non-azeotropic mixed refrigerant as a working refrigerant. In the air conditioner, the outdoor heat exchanger and the indoor heat exchanger are composed of heat transfer fins and heat transfer tubes that are inner surface processing tubes, and the outdoor heat exchanger has a rated capacity when acting as an evaporator. The air conditioner, wherein the control device controls the number of revolutions of the compressor so that the refrigerant mass velocity is 200 to 400 kg / s. 6. An indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, an expansion mechanism, a control device for controlling the rotation speed of the compressor, and a non-azeotropic mixed refrigerant as a working medium. In the air conditioner, the indoor heat exchanger and the outdoor heat exchanger are composed of heat transfer fins and heat transfer tubes that are inner surface processing tubes, and the rated capacity when the outdoor heat exchanger acts as an evaporator Has a refrigerant passage cross-sectional area of 0.1 to 0.21 cm ^2.
An air conditioner characterized in that the pipe diameter and the number of passes are selected so that it becomes / kW. 7. An indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, an expansion mechanism, a control device for controlling the rotation speed of the compressor, and a non-azeotropic mixed refrigerant as a working medium. In the air conditioner, the heat exchanger is composed of heat transfer fins and a heat transfer tube that is an inner surface processing tube, the refrigerant mass velocity in the tube is relatively large, and at least the refrigerant at the rated capacity when acting as an evaporator is used. An air conditioner having a refrigerant passage cross-sectional area set so that an inlet evaporation temperature is within an allowable range of an outlet evaporation temperature. 8. An indoor heat exchanger, an outdoor heat exchanger, a compressor, a four-way valve, an expansion mechanism, a control device for controlling the rotation speed of the compressor, and a non-azeotropic mixed refrigerant as a working medium. In the above air conditioner, a sensor for detecting a refrigerant evaporation temperature is provided on the outlet side of the outdoor heat exchanger, and the outlet side superheater of the heat exchanger when the refrigerant temperature detected by the sensor acts as an evaporator. An air conditioner that outputs a refrigerant leak alarm when it is determined that the heat amount is larger than the allowable value. 9. The air conditioner according to claim 1, wherein the cross sectional area of the refrigerant passage of the indoor heat exchanger is set smaller than the cross sectional area of the refrigerant passage of the outdoor heat exchanger. 10. The air conditioner according to claim 1, wherein the outdoor heat exchanger and the indoor heat exchanger are provided with a slit in an intermediate portion.