JP2883536B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner having a plurality of condensers, and more particularly, to a subcooled type in which a non-azeotropic mixed refrigerant comprising a high-boiling refrigerant and a low-boiling refrigerant is used. (SC) The present invention relates to an air conditioner capable of performing control.

[0002]

2. Description of the Related Art Generally, a refrigerant circuit of a multi-type heat pump type air conditioner having a plurality of indoor heat exchangers is shown in FIG.
, A compressor 1, an indoor heat exchanger (condenser) 2
a and 2b are constituted by a flow control valve 3, an outdoor heat exchanger 4, a four-way valve 5, and the like. During the heating operation, the refrigerant is circulated in this order as indicated by solid arrows, and the cooling operation is the reverse of the heating operation. The refrigerant is circulated in the direction.

In this multi-type heat pump type air conditioner, a plurality of indoor heat exchangers (condensers) 2a and 2b are arranged in parallel, and a plurality of indoor air is adjusted by one refrigerant circuit. .

Further, in a heat pump type air conditioner, a cooling operation and a heating operation are performed by one circuit by switching a refrigerant flow path.

On the other hand, in such a heat pump type heat exchanger, when a single refrigerant (for example, R-22) is used as the refrigerant, when the pressure of the single refrigerant is constant, the gas-liquid mixing is not performed. The temperature of the refrigerant becomes constant, and the inlet temperature and the outlet temperature in the indoor heat exchangers 2a and 2b can be made equal.

That is, as shown in the Mollier diagram shown in FIG. 6, if the pressure of a single refrigerant is constant, the saturation temperature is also constant,
There is no temperature gradient between the inlet side and the outlet side of the indoor heat exchangers (condensers) 2a, 2b, that is, a temperature glide.
Since there is no e), the intermediate temperature (condensation temperature) can be measured at any part of the indoor heat exchangers 2a and 2b and used as the condensing temperature.

In the condensers 2a and 2b, when observing the sub-cooled state of the indoor heat exchangers (condensers) 2a and 2b, the condenser temperature T11 in the condensers 2a and 2b shown in FIG. Due to the temperature difference from the outlet temperature T12 of FIG.
The outlet temperature T12) was detected, and the refrigerant circuit of FIG. 5 was subjected to subcool control.

[0008]

However, when a non-azeotropic refrigerant mixture of a high-boiling refrigerant and a low-boiling refrigerant is used as the refrigerant in the refrigerant circuit of FIG.
Since the refrigerant having a low boiling point evaporates first, this is different from the Mollier diagram in the case where the single refrigerant shown in FIG. 6 is used. That is, when the pressure of the non-azeotropic refrigerant mixture is constant and the gas-liquid mixture is performed, the isotherm of the non-azeotropic refrigerant mixture falls rightward from the saturated liquid line to the saturated vapor line (temperature glide: About 5 °
C).

Due to this temperature glide, the condenser 2
Is not necessarily the condensation temperature of the condensers 2a and 2b. That is, when a non-azeotropic refrigerant mixture is used, the correct condensation temperature of the condensers 2a and 2b cannot be detected.

Therefore, when a non-azeotropic refrigerant mixture is used,
The condensation temperature T11 in the conventional condensers 2a and 2b of FIG.
And the temperature difference between the outlet temperature T12 of the condenser 2 and
There is a problem that the subcool SC of the condenser 2 cannot be detected to determine whether the refrigerant is in a liquid state or a wet state.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multi-unit air conditioner capable of detecting and controlling subcooling even when a non-azeotropic mixed refrigerant having a temperature glide is used. It is intended to provide.

[0012]

The first invention uses a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant as a refrigerant of a refrigeration cycle having a plurality of condensers arranged in parallel. An air conditioner of a multi-unit type in which a flow rate control valve for controlling a flow rate of a refrigerant flowing through each condenser is provided at an outlet of each condenser, wherein the flow rate control is performed at an outlet side of each condenser. A first temperature sensor and a second temperature sensor for detecting a refrigerant temperature are provided before and after the valve.

According to a second aspect of the present invention, a single refrigerant or a non-azeotropic mixed refrigerant comprising a high-boiling refrigerant and a low-boiling refrigerant is used as a refrigerant for a refrigeration cycle having a plurality of condensers arranged in parallel. At the outlet of the condenser, a multi-type air conditioner provided with a flow control valve for controlling the flow rate of the refrigerant flowing through each condenser, and at the outlet side of each condenser, before and after the flow control valve. And a first temperature sensor and a second temperature sensor for detecting a refrigerant temperature.

According to a third aspect of the present invention, a single refrigerant or a non-azeotropic refrigerant mixture of a high-boiling refrigerant and a low-boiling refrigerant is used as a refrigerant for a refrigeration cycle having a plurality of condensers arranged in parallel. At the outlet of the condenser is a multi-type air conditioner provided with a flow control valve that controls the flow rate of the refrigerant flowing through each condenser, at the outlet of each condenser, before and after the flow control valve , The first to detect the refrigerant temperature
And a second temperature sensor for adjusting the opening of the flow control valve based on the detected temperatures.

[0015]

According to the first aspect of the present invention, the flow rate control valve provided on the outlet side of each condenser acts as a resistor to give a certain resistance to the refrigerant, and the first temperature before and after this resistance is obtained. A change in temperature due to resistance is detected by the sensor and the second temperature sensor. Thereby, the state of the refrigerant at the outlet of the condenser, that is, whether the refrigerant is in a liquid state or a wet gas state is determined, and when a non-azeotropic mixed refrigerant is used as the refrigerant, subcool detection and control can be performed.

Since the existing flow control valve is used as the resistor, there is no need to provide a separate resistor.

According to the second aspect of the invention, even when a single refrigerant as well as a mixed refrigerant is used, the first temperature sensor and the second temperature sensor in front of and behind the flow control valve are provided as in the first aspect. Temperature change with the temperature sensor. Thus, when a single refrigerant or a mixed refrigerant is used, the temperature difference according to the refrigerant state can be set freely, so that the detection and control of the subcool can be reliably performed.

Since the present invention detects the gas-liquid state of the refrigerant, the subcooling can be adjusted even in the case of a single refrigerant, as in the case of the mixed refrigerant.

According to the third invention, the size of the subcool can be adjusted by adjusting the opening of the flow control valve based on the temperatures detected by the first temperature sensor and the second temperature sensor.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a refrigerant circuit diagram of an embodiment according to the air conditioner of the present invention. In the air conditioner according to this embodiment, a non-azeotropic mixed refrigerant including a high-boiling refrigerant and a low-boiling refrigerant is used as the refrigerant circulating in the refrigerant circuit.

In the refrigerant circuit of FIG. 1, a compressor 13, indoor heat exchangers (condensers) 15a and 15b, a flow control valve 16
a, 16b, an expansion valve 17, an outdoor heat exchanger 19, a four-way valve 31 as a flow path switching valve, and an accumulator 33 are arranged in this order.

The indoor heat exchangers 15a, 15b of the present embodiment
Are provided in parallel, and the number of indoor heat exchangers, not limited to two, but three, four, etc. can be increased as necessary. As described above, the present embodiment is a so-called multi-type heat pump air conditioner, in which a single refrigerant circuit can cool or heat a plurality of rooms.

The outdoor heat exchanger 19 as a heat exchanger and the indoor heat exchangers 15a and 15b each have a fan, and the outdoor air or the indoor air exchanges heat.

Each of the indoor heat exchangers 15a and 15b is provided with flow control valves 16a and 16b at the outlet side.
The inflow of the refrigerant is controlled for each of the indoor heat exchangers 15a and 15b. In the present embodiment, these flow control valves 16a and 16b are used as variable resistances of the flow paths, respectively.

The outlet side of the indoor heat exchanger 15 and the flow control valve 1
A first temperature sensor 40 is disposed between the flow control valves 16a and 16b and the flow control valves 16a and 16b and the valve 17.
A second temperature sensor 42 is disposed between the two. That is, the temperature sensors 40 and 42 are disposed before and after (upstream and downstream) the flow control valves 16a and 16b.

The four-way valve 31 is positioned so as to flow the refrigerant as indicated by a broken line during a cooling operation, and is positioned as indicated by a solid line during a heating operation. By switching the four-way valve 31 in this manner, the cooling and heating refrigerant flow paths are switched.

In the heat pump type air conditioner, during the cooling operation, when the indoor heat exchanger 15 functions as an evaporator, the outdoor heat exchanger 19 functions as a condenser. When the indoor heat exchanger 15 acts as a condenser, the outdoor heat exchanger 19 acts as an evaporator.

As the non-azeotropic mixed refrigerant, for example, R13
A mixed refrigerant of 4a, R125 and R32 is used. Generally, the boiling point of R134a is -26 degrees Celsius, the boiling point of R125 is -48 degrees Celsius, and the boiling point of R32 is -52 degrees Celsius.

Next, the operation of the above embodiment will be described.

In the refrigerant circuit of FIG. 1, during the cooling operation, the four-way valve 31 of FIG. 1 is positioned as shown by a broken line, and the compressor 13, the outdoor heat exchanger 19, the expansion valve 17, the flow control valve 1
6a, 16b, indoor heat exchangers 15a, 15b, four-way valve 3
1. The refrigerant is circulated in the order of the accumulator 33. During the cooling operation, the outdoor heat exchanger 19 acts as a condenser, and the indoor heat exchanger 15 acts as an evaporator, and the refrigerant is vaporized and draws heat from indoor air.

On the other hand, in the refrigerant circuit of FIG. 1, during the heating operation, the four-way valve 31 is positioned as shown by the solid line in FIG.
As indicated by the arrows, the refrigerant is supplied to the compressor 13 and the indoor heat exchanger 1.
5a, 15b, flow control valves 16a, 16b, expansion valve 1
7, outdoor heat exchanger 19, four-way valve 31, accumulator 3
The refrigerant is circulated in the order of 3. At this time, the first temperature sensor 40 is connected to the indoor heat exchanger 15a acting as a condenser,
15b and the flow control valve 16 acting as a resistance
The temperature of the refrigerant is detected between a and 16b. The second temperature sensor 42 is connected to the flow control valves 16 a and 16 b and the expansion valve 1.
7, the temperature of the refrigerant is detected.

During the heating operation, the refrigerant introduced into the indoor heat exchangers 15a and 15b from the compressor 13 exchanges heat with the indoor air. An indoor heat exchanger 15a acting as a condenser,
The refrigerant having passed through 15b is supplied to the flow control valves 16a, 16b,
The refrigerant is introduced into the outdoor heat exchanger 19 via the expansion valve 17, and the outdoor heat exchanger 19 acts as an evaporator, and the refrigerant is vaporized to generate heat from the outside air.

During the heating operation, the indoor heat exchangers 15a, 15
In FIG. 2B, as shown in FIG. 2, in the non-azeotropic mixed refrigerant composed of the high-boiling refrigerant and the low-boiling refrigerant, the low-boiling refrigerant evaporates first, so that the isotherm of the non-azeotropic mixed refrigerant is the saturated liquid line. From the indoor heat exchanger 15
Temperature glide occurs between the inlet side and the outlet side of a and 15b.

Because of this temperature glide, the intermediate temperature between the indoor heat exchangers 15a and 15b is not always the condensing temperature of the indoor heat exchanger 2. That is, the temperature of the indoor heat exchanger 2 cannot be detected.

Therefore, in the embodiment of the present invention, the flow rate control valves 16a and 16b are provided at the outlets of the indoor heat exchangers 15a and 15b which function as condensers during the heating operation, and the flow rate control valves 16a and 16b pass through the flow rate control valves 16a and 16b. It is known that the temperature difference between the flow control valves 16a and 16b varies depending on the state of the refrigerant, that is, the mixing ratio of the liquid refrigerant and the refrigerant vapor (whether the refrigerant is in a liquid state or in a wet gas state). ing. Therefore, by detecting the temperature difference by the first and second temperature sensors 40 and 42 disposed before and after the flow control valves 16a and 16b, and adjusting the opening of the expansion valve 17 based on the temperature difference, The value of the subcool SC is adjusted.

The specific subcool SC control will be described below.

T1 shown in FIG. 3 is a flow control valve 16a, 16
b indicates the temperature before T, and T2 is the flow control valve 16a, 16b
The temperature after is shown.

As shown in FIG. 2, when the subcool SC1 is set at 5 ° C. for a certain circulation amount, the difference between P1 (the pressure before the fixed resistance) and P2 (the pressure after the fixed resistance), that is, ΔP1 Is required at 1.5 kg / cm 2. At that time, the difference between the temperature T1 before the fixed resistor and the temperature T2 after the fixed resistor, ΔT, is about 2 ° C.

As shown in FIG. 2, when the subcool SC2 is set to 10 ° C. for a certain circulation amount, P1
The difference between (the pressure before the fixed resistance) and P2 (the pressure after the fixed resistance), that is, ΔP2 is required to be 2-3 kg / cm 2. At that time, the difference between the temperature T1 before the flow control valves 16a and 16b and the temperature T2 after the flow control valves 16a and 16b, ΔT, is about 1 ° C.

ΔT regarding the size of the subcool SC
The relationship between ΔP and ΔP is as shown in FIG. As is clear from FIG. 4, in an air conditioner using a non-azeotropic mixed refrigerant,
If the number of subcools SC is large, ΔT is decreased, and if the number of subcools SC is small, ΔT is increased.

In the embodiment shown in FIG. 1, since the flow control valves 16a and 16b are used as resistors, the flow control valves are adjusted according to the required size of the subcool SC depending on the size of the indoor heat exchanger. The sub-cool SC is detected and the refrigerant circuit is subjected to sub-cool control by adjusting the opening degrees of 16a and 16b and taking the above-mentioned temperature difference.

Further, as shown in FIG.
The opening degrees of the flow control valves 16a and 16b are changed so that ΔT is decreased when a large amount of C is taken and ΔT is increased when the subcool SC is not so large. That is, as shown in FIG. 3, the flow control valves 16a and 16b are throttled from fully open. Preferably, the subcool SC is set to zero when fully opened.

The present invention is not limited to the embodiments described above,
Various modifications can be made without departing from the spirit of the present invention.

For example, the heat source can be not only air but also water. Further, since the present invention is to detect the gas-liquid state of the refrigerant, as the refrigerant, in addition to the non-azeotropic mixed refrigerant,
The same effect can be obtained by using a single refrigerant.

[0046]

According to the first aspect of the present invention, the flow control valve provided on the outlet side of each condenser acts as a resistor to give a certain resistance to the refrigerant, and the first and second resistances before and after this resistance are provided. Since the temperature sensor and the second temperature sensor are provided to detect a change in temperature due to resistance, the state of the refrigerant at the outlet of the condenser, that is, a liquid state or a wet gas state is determined,
When a non-azeotropic mixed refrigerant is used as the refrigerant, detection and control of the subcool can be performed. Therefore, even when a non-azeotropic mixed refrigerant having a temperature glide is used, subcool detection and control can be performed.

Further, since the existing flow control valve is used as the resistor, there is no need to provide a separate resistor.

According to the second aspect of the invention, even when a single refrigerant as well as a mixed refrigerant is used, the first temperature sensor and the second temperature sensor before and after the flow control valve can be used similarly to the first aspect of the invention. By detecting a temperature change with the temperature sensor, the detection and control of the subcool can be reliably performed.

According to the third invention, the size of the subcool can be adjusted by adjusting the opening of the flow control valve based on the temperatures detected by the first temperature sensor and the second temperature sensor.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner of the present invention.

FIG. 2 is a Mollier diagram in the embodiment of FIG.

FIG. 3 is an enlarged view of the Mollier diagram of FIG. 2;

FIG. 4 is a diagram showing a relationship among temperature, pressure, and subcool.

FIG. 5 is a refrigerant circuit diagram showing a conventional multi-type air conditioner.

FIG. 6 is a Mollier diagram for a single refrigerant.

[Explanation of symbols]

 13 Compressor 15a, 15b Condenser (indoor heat exchanger) 16a, 16b Flow control valve 40 First temperature sensor 42 Second temperature sensor

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI F25B 49/02 510 F25B 49/02 510C (72) Inventor Kazuhiro Shimura 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo (58) Field surveyed (Int.Cl. ⁶ , DB name) F25B 13/00 F25B 1/00 F25B 49/02

Claims (3)

(57) [Claims] 1. A non-azeotropic mixed refrigerant comprising a high-boiling refrigerant and a low-boiling refrigerant is used as a refrigerant of a refrigeration cycle having a plurality of condensers arranged in parallel, and each condenser has an outlet at the outlet of each condenser. A multi-unit air conditioner provided with a flow control valve for controlling the flow rate of refrigerant flowing through the condenser, wherein at the outlet side of each of the condensers, a refrigerant temperature is detected before and after the flow control valve. An air conditioner comprising a first temperature sensor and a second temperature sensor. 2. A single refrigerant or a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant is used as a refrigerant of a refrigeration cycle having a plurality of condensers arranged in parallel, and outlets of these condensers are used. A multi-type air conditioner provided with a flow control valve for controlling the flow rate of the refrigerant flowing through each condenser, wherein at the outlet side of each condenser, before and after the flow control valve, the refrigerant temperature. An air conditioner comprising: a first temperature sensor and a second temperature sensor for detecting a temperature. 3. A single refrigerant or a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant is used as a refrigerant of a refrigeration cycle having a plurality of condensers arranged in parallel, and outlets of these condensers are used. A multi-unit air conditioner provided with a flow control valve for controlling the flow rate of the refrigerant flowing through each condenser, wherein at the outlet of each condenser, before and after the flow control valve, the refrigerant temperature An air conditioner, comprising: a first temperature sensor and a second temperature sensor for detecting pressure, and adjusting the opening of the flow control valve based on the detected temperatures.