JP2022173639A - air conditioner - Google Patents

Abstract

To suppress deterioration in performance when operation capacity of a compressor increases.SOLUTION: An air conditioner includes: a gas engine 103, a first compressor 101, a second compressor 102, an oil separator 104, an oil return pipe 105, a first branch oil return pipe 111, a second branch oil return pipe 112, a by-pass pipe 118, an oil refrigerant heat exchanger 121, and an exhaust heat recovery decompression device 120. The exhaust heat recovery decompression device 120 is opened or closed by air conditioning load of the air conditioner, and exchanges heat between oil flowing through the oil return pipe 105 and refrigerant flowing through the by-pass pipe 112 using the oil refrigerant heat exchanger 121.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an air conditioner in which a compressor driven by a gas engine and a compressor driven by an electric motor are mounted in parallel.

Patent Literature 1 discloses a refrigeration cycle device having an oil equalizing function for multiple compressors. This refrigeration cycle device includes a single oil separator, a plurality of compressors connected to the oil separator via oil return pipes, oil return valves provided in the oil return pipes, and A control means for detecting operating capacities and controlling each oil return valve so that the operating capacity ratio and the ratio of the opening of each oil return valve or the ratio of the opening time of each oil return valve match.

JP-A-2010-48460

The present disclosure provides an air conditioner that prevents deterioration in performance when the operating capacity of the compressor increases.

An air conditioner according to the present disclosure is an air conditioner in which a first compressor having a gas engine as a drive source and a second compressor having an electric motor as a drive source are connected in parallel to perform air conditioning by circulating a refrigerant. , an oil separator downstream from the confluence of the discharge pipes of the first compressor and the second compressor, an oil return pipe connected to the bottom of the oil separator, and the first oil return pipe branched from the oil return pipe. A first branched oil return pipe that connects the suction pipe of the compressor, a second branched oil return pipe that branches from the oil return pipe and connects the suction pipe of the second compressor, and a refrigerant liquid pipe and an accumulator. and a bypass pipe that connects an upstream low-pressure gas pipe, and the oil return pipe and the bypass pipe are provided with a heat exchange portion that exchanges heat between the oil and the refrigerant.

In the air conditioner according to the present disclosure, the high-temperature and high-pressure oil separated by the oil separator is heat-exchanged with the low-temperature and low-pressure refrigerant in the heat exchange unit that exchanges heat between the oil and the refrigerant, and the oil temperature when flowing into the compressor suction pipe is reduced. can be lowered. Therefore, it is possible to suppress insufficient performance when the temperature of the refrigerant sucked into the compressor is lowered and the density of the refrigerant sucked into the compressor is increased, that is, when the operating capacity of the compressor is increased.

1 is a configuration diagram showing an air conditioner according to Embodiment 1 of the present invention.

(Knowledge, etc. on which this disclosure is based)
At the time when the inventors arrived at the present disclosure, the compressor discharged part of the lubricating oil for the compressor together with the refrigerant during its operation, and the discharged lubricating oil returned to the compressor. Without it, the amount of oil in the compressor that lubricates the sliding parts gradually decreases, causing malfunction. There was a technology to provide an oil return circuit for returning the separated lubricating oil to the compressor.
Here, since air conditioners using compressors driven by gas engines are used in office buildings and large stores, there are cases where multiple compressors with large operating capacities are connected in parallel and used. . In a refrigeration cycle apparatus in which a plurality of compressors are connected in parallel, as in the conventional technology, an oil equalization function is required for the plurality of compressors.

However, when the oil return valve is controlled according to the operating capacity of the compressor as in the conventional technology, when the operating capacity is large and the amount of oil returned is large, the refrigerant sucked into the compressor receives heat from the return oil. However, the inventors discovered the problem that the density of the sucked refrigerant is reduced, that is, the refrigerant circulation amount is reduced, and the desired performance cannot be exhibited. Arrived.
Accordingly, the present disclosure provides an air conditioner that prevents deterioration in performance when the operating capacity of the compressor increases.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially the same configurations may be omitted. This is to avoid the following description from becoming more redundant than necessary and to facilitate understanding by those skilled in the art.
It should be noted that the accompanying drawings and the following description are provided to allow those skilled in the art to fully understand the present disclosure and are not intended to limit the claimed subject matter thereby.

(Embodiment 1)
[1-1. Constitution]
FIG. 1 shows the configuration of an air conditioner 300 according to the first embodiment of the invention.
In FIG. 1, the air conditioner includes an outdoor unit 100 and an indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected by unit piping.

The outdoor unit 100 includes a first compressor 101 driven by a gas engine 103 and a second compressor 102 driven by an electric motor. are connected in parallel. Also, the first compressor 101 is selected to have a larger capacity than the second compressor 102 .

The outdoor unit 100 includes an oil separator 104, a four-way valve 106, an outdoor heat exchanger 107, a pressure reducing device 109, an accumulator 110, a radiator 116, an exhaust heat recovery heat exchanger 119, and an exhaust heat recovery pressure reducing device 120. and

The oil separator 104 is installed downstream of the confluence of the discharge pipes of the first compressor 101 and the second compressor 102, and separates the oil contained in the refrigerant gas discharged from the compressors. The oil separated by the oil separator 104 is returned to the suction pipes of the first compressor 101 and the second compressor 102 through an oil return pipe 105 connected to the bottom of the oil separator 104 .
The four-way valve 106 is for switching the refrigerating cycle between cooling and heating. The outdoor heat exchanger 107 radiates the heat of the refrigerant to the outside during cooling by the outdoor fan 108, and absorbs the heat of the outside air during heating. A decompression device 109 adjusts the pressure and flow rate of the refrigerant. The accumulator 110 is connected to a low-pressure gas pipe 115 upstream of the branch point of the suction pipe 111 of the first compressor 101 and the suction pipe 112 of the second compressor 102, which are connected in parallel. Gas refrigerant is supplied to the compressor 102 .

The radiator 116 is arranged on the leeward side of the outdoor heat exchanger 107 and uses the outdoor fan 108 to radiate the heat of the engine cooling water. The exhaust heat recovery heat exchanger 119 and the exhaust heat recovery pressure reduction device 120 are installed in the bypass pipe 118 that connects the refrigerant liquid pipe 117 and the low pressure gas pipe 115, and during heating, the refrigerant can also absorb heat from the engine cooling water. ing.

Also, the oil return pipe 105 has one end connected to the bottom surface of the oil separator 104, the other end is branched, and one end is connected to the suction pipe 111 of the first compressor 101, a first branched oil return pipe 113; The other is composed of a second branch oil return pipe 114 connected to the suction pipe 112 of the second compressor 102 .

Further, an oil-refrigerant heat exchanger 121 is installed between the oil return pipe 105 and the bypass pipe 118 as a heat exchange unit that exchanges heat between the return oil and the refrigerant passing through the bypass pipe 118 .

The indoor unit 200 includes an indoor heat exchanger 201, an indoor blower fan 202, and an indoor unit pressure reducing device 203 that expands the refrigerant.
Although only one indoor unit 200 is installed in FIG. 1 , a plurality of units may be installed in parallel with the outdoor unit 100 .

[1-2. motion]
Next, the operation of the outdoor unit 100 and the indoor unit 200 will be described with reference to FIG. 1, divided into required load magnitudes in cooling operation, heating operation, and each operating state.

(at low cooling load)
During low-load cooling operation, only the second compressor 102 driven by the electric motor is driven. The exhaust heat recovery decompression device 120 is closed. The four-way valve 106 is set to allow coolant to flow along the dotted line.
The high-temperature, high-pressure refrigerant compressed by the second compressor 102 flows into the oil separator 104 . The high-purity gas refrigerant from which the oil is separated by the oil separator 104 passes through the four-way valve 106 and enters the outdoor heat exchanger 107 . The gas refrigerant exchanges heat with the outside air in the outdoor heat exchanger 107 , radiates heat, is condensed, becomes a high-pressure liquid refrigerant, and is supplied to the indoor unit 200 through the decompression device 109 .

The high-pressure liquid refrigerant that has entered the indoor unit 200 is decompressed by the indoor unit decompression device 203 , becomes a gas-liquid two-phase state, and flows into the indoor heat exchanger 201 . The gas-liquid two-phase refrigerant exchanges heat with the air in the space to be air-conditioned in the indoor heat exchanger 201 , absorbs heat, evaporates, and flows out of the indoor unit 200 as a gas refrigerant.
The gas refrigerant that has flowed out of the indoor unit 200 returns to the outdoor unit 100 again. The gas refrigerant that has flowed into the outdoor unit 100 passes through the four-way valve 106, the accumulator 110, and the suction pipe 112 of the second compressor 102, returns to the second compressor 102, and repeats the above process.
Also, the lubricating oil separated by the oil separator 104 is returned to the suction pipe 112 of the second compressor 102 through the oil return pipe 105 and the second branched oil return pipe 114, and the above process is repeated.

(At load during cooling operation)
During medium load in cooling operation, the first compressor 101 driven by the gas engine 103 is driven. The exhaust heat recovery decompression device 116 is closed. The four-way valve 105 is set so that the coolant flows along the dotted line.
The high-temperature and high-pressure refrigerant compressed by the first compressor 101 flows into the oil separator 104 . The high-purity gas refrigerant from which the oil is separated by the oil separator 104 passes through the four-way valve 106 and enters the outdoor heat exchanger 107 . The gas refrigerant exchanges heat with the outside air in the outdoor heat exchanger 107 , radiates heat, is condensed, becomes a high-pressure liquid refrigerant, and is supplied to the indoor unit 200 through the decompression device 109 .

The high-pressure liquid refrigerant that has entered the indoor unit 200 is decompressed by the indoor unit decompression device 203 , becomes a gas-liquid two-phase state, and flows into the indoor heat exchanger 201 . The gas-liquid two-phase refrigerant exchanges heat with the air in the space to be air-conditioned in the indoor heat exchanger 201 , absorbs heat, evaporates, and flows out of the indoor unit 200 as a gas refrigerant.
The gas refrigerant that has flowed out of the indoor unit 200 returns to the outdoor unit 100 again. The gas refrigerant that has flowed into the outdoor unit 100 passes through the four-way valve 106 and the accumulator 110, returns to the first compressor 101, and repeats the above process.

The lubricating oil separated by the oil separator 104 is returned to the suction pipe 111 of the first compressor 101 through the oil return pipe 105 and the first branched oil return pipe 113, and the above process is repeated.
Exhaust heat generated by the gas engine 103 is carried to the radiator 114 by engine cooling water and a pump (not shown), exchanges heat with the outside air, and returns to the gas engine 103 again.

(at high cooling load)
During high-load cooling operation, both the first compressor 101 driven by the gas engine 103 and the second compressor 102 driven by the electric motor are driven. The exhaust heat recovery decompression device 116 is opened. The four-way valve 106 is set to allow coolant to flow along the dotted line.
The high-temperature, high-pressure refrigerant compressed by the first compressor 101 and the second compressor 102 flows into the oil separator 104 . The refrigerant that has flowed into the oil separator 104 becomes a high-purity gas refrigerant from which the oil has been separated, passes through the four-way valve 106 , and enters the outdoor heat exchanger 107 . The gas refrigerant exchanges heat with the outside air in the outdoor heat exchanger 107 , radiates heat, is condensed, becomes a high-pressure liquid refrigerant, and is supplied to the indoor unit 200 through the decompression device 109 .

The high-pressure liquid refrigerant that has entered the indoor unit 200 is decompressed by the indoor unit decompression device 203 , becomes a gas-liquid two-phase state, and flows into the indoor heat exchanger 201 . The gas-liquid two-phase refrigerant exchanges heat with the air in the space to be air-conditioned in the indoor heat exchanger 201 , absorbs heat, evaporates, and flows out of the indoor unit 200 as a gas refrigerant.
The gas refrigerant that has flowed out of the indoor unit 200 returns to the outdoor unit 100 again. The gas refrigerant that has flowed into the outdoor unit 100 passes through the four-way valve 106 and the accumulator 110, then branches, passes through the suction pipe 111 of the first compressor to the first compressor 101, and passes through the suction pipe 112 of the second compressor. to return to the second compressor 102 and repeat the above process.

In addition, the lubricating oil separated by the oil separator 104 passes through the oil return pipe 105, and part of it passes through the first branch oil return pipe 113 and the suction pipe 111 of the first compressor 101 to the first compressor 101. , the rest passes through the second branched oil return pipe 114 and the suction pipe 112 of the second compressor 102, returns to the second compressor 102, and repeats the above process.

Exhaust heat generated by the gas engine 103 is carried to the radiator 116 by engine cooling water and a pump (not shown), exchanges heat with the outside air, and returns to the gas engine 103 again.
At this time, since the exhaust heat recovery decompression device 120 is open, the high-temperature and high-pressure lubricating oil separated by the oil separator 104 passes through the oil-refrigerant heat exchanger 121 while passing through the oil-refrigerant heat exchanger 121. The refrigerant is decompressed in the device 120 and exchanges heat with the low-temperature, low-pressure refrigerant. In addition, the low-temperature, low-pressure refrigerant decompressed by the exhaust heat recovery decompression device 120 is returned to the first compressor 101 and the second compressor 102 as medium-temperature, low-pressure refrigerant.

(at low heating load)
During low-load heating operation, only the second compressor 102 driven by the electric motor is driven. The exhaust heat recovery decompression device 120 is closed. The four-way valve 106 is set to allow the coolant to flow along the solid line.
The high-temperature, high-pressure refrigerant compressed by the second compressor 102 flows into the oil separator 104 . The high-purity gas refrigerant from which the oil is separated by the oil separator 104 is supplied to the indoor unit 200 through the four-way valve 106 .

The high-temperature and high-pressure gas refrigerant that has entered the indoor unit 200 flows into the indoor heat exchanger 201, exchanges heat with the air in the space to be air-conditioned, releases heat, condenses, becomes liquid refrigerant, and depressurizes the indoor unit. It flows out of the indoor unit 200 through the device 203 .
The liquid refrigerant that has flowed out of the indoor unit 200 returns to the outdoor unit 100 again. The liquid refrigerant that has flowed into the outdoor unit 100 is decompressed by the decompression device 109 and enters the outdoor heat exchanger 107 in a gas-liquid two-phase state. The gas-liquid two-phase refrigerant exchanges heat with the outside air in the outdoor heat exchanger 107, absorbs heat, evaporates, becomes a gaseous refrigerant, passes through the four-way valve 106 and the accumulator 110, returns to the second compressor 102, and returns to the second compressor 102. repeat the process.

Also, the lubricating oil separated by the oil separator 104 is returned to the suction pipe 112 of the second compressor 102 through the oil return pipe 105 and the second branched oil return pipe 114, and the above process is repeated.

(During heating load)
During medium-load heating operation, the first compressor 101 driven by the gas engine 103 is driven. The exhaust heat recovery decompression device 116 is closed. The four-way valve 106 is set to allow the coolant to flow along the solid line.
The high-temperature and high-pressure refrigerant compressed by the first compressor 101 flows into the oil separator 104 . The high-purity gas refrigerant from which the oil is separated by the oil separator 104 is supplied to the indoor unit 200 through the four-way valve 106 .

The high-temperature and high-pressure gas refrigerant that has entered the indoor unit 200 flows into the indoor heat exchanger 201, exchanges heat with the air in the space to be air-conditioned, releases heat, condenses, becomes liquid refrigerant, and depressurizes the indoor unit. It flows out of the indoor unit 200 through the device 203 .
The liquid refrigerant that has flowed out of the indoor unit 200 returns to the outdoor unit 100 again. The liquid refrigerant that has flowed into the outdoor unit 100 is decompressed by the decompression device 109 and enters the outdoor heat exchanger 107 in a gas-liquid two-phase state. The gas-liquid two-phase refrigerant exchanges heat with the outside air, absorbs heat, and then evaporates to become a gas refrigerant. After that, it returns to the first compressor 101 through the four-way valve 106 and the accumulator 110, and repeats the above process.

The lubricating oil separated by the oil separator 104 is returned to the suction pipe 111 of the first compressor 101 through the oil return pipe 105 and the first branched oil return pipe 113, and the above process is repeated.

(heating high load)
During high-load heating operation, the first compressor 101 driven by the gas engine 103 and the second compressor 102 driven by the electric motor are driven. The exhaust heat recovery decompression device 116 is opened. The four-way valve 106 is set to allow the coolant to flow along the solid line.
The high-temperature, high-pressure refrigerant compressed by the first compressor 101 and the second compressor 102 flows into the oil separator 104 . The refrigerant that has flowed into the oil separator 104 becomes high-purity gas refrigerant from which the oil is separated, passes through the four-way valve 106 , and is supplied to the indoor unit 200 .

The high-temperature and high-pressure gas refrigerant that has entered the indoor unit 200 flows into the indoor heat exchanger 201, exchanges heat with the air in the space to be air-conditioned, releases heat, condenses, becomes liquid refrigerant, and depressurizes the indoor unit. It flows out of the indoor unit 200 through the device 203 .
The liquid refrigerant that has flowed out of the indoor unit 200 returns to the outdoor unit 100 again. Part of the liquid refrigerant that has flowed into the outdoor unit 100 flows into the bypass pipe 118 . The remaining liquid refrigerant that has not flowed into the bypass pipe 118 is decompressed by the decompression device 109 and enters the outdoor heat exchanger 107 in a gas-liquid two-phase state. The gas-liquid two-phase refrigerant exchanges heat with the outside air, absorbs heat, and then evaporates to become a low-temperature, low-pressure gas refrigerant. After that, it passes through the four-way valve 106 and the accumulator 110, part of it passes through the suction pipe 111 of the first compressor 101 and returns to the first compressor 101, and the rest passes through the suction pipe 112 of the second compressor 102 to the second compressor. 2 Return to compressor 102 .

At this time, since the exhaust heat recovery decompression device 116 is open, the high-temperature and high-pressure lubricating oil separated by the oil separator 104 passes through the oil-refrigerant heat exchanger 121 while passing through the oil return pipe 105. The refrigerant is decompressed by the device 116 and exchanges heat with the low-temperature and low-pressure refrigerant, and is returned to the first compressor 101 and the second compressor 102 after becoming medium-temperature and high-pressure. In addition, the refrigerant depressurized by the exhaust heat recovery decompression device 116 and reduced to a low temperature and low pressure is reduced to a medium temperature and low pressure, and then heat-exchanged with the engine cooling water by the exhaust heat recovery heat exchanger 115 to obtain a high temperature and low pressure gas refrigerant. , and is returned to the first compressor 101 and the second compressor 102 .

[1-3. effects, etc.]
As described above, in the present embodiment, the air conditioner 300 includes the gas engine 103, the first compressor 101, the second compressor 102, the oil separator 104, the oil return pipe 105, the first branch An oil return pipe 111 , a second branched oil return pipe 112 , a bypass pipe 118 , an oil refrigerant heat exchanger 121 and an exhaust heat recovery pressure reducing device 120 are provided. The exhaust heat recovery decompression device 120 is configured to open and close according to the air conditioning load of the air conditioner, and to exchange heat between the oil flowing through the oil return pipe 105 and the refrigerant flowing through the bypass pipe 112 with the oil-refrigerant heat exchanger 121. ing.
As a result, the air conditioner 300 can cool the oil returned from the oil separator 104 by the refrigerant flowing through the bypass pipe 118 according to the air conditioning load. Therefore, it is possible to suppress the temperature rise of the refrigerant sucked into the compressor by receiving heat from the return oil, thereby increasing the density of the refrigerant sucked into the compressor, that is, suppressing insufficient performance when the operating capacity of the compressor increases. .
Note that the above-described embodiment is for illustrating the technology in the present disclosure, and various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or equivalents thereof.

The air conditioner according to the present invention can be suitably used as an air conditioner capable of highly efficient operation regardless of the air conditioning load by selecting the drive source for the compressor according to the air conditioning load. can be done.

100 outdoor unit 101 first compressor 102 second compressor 103 gas engine 104 oil separator 105 oil return pipe 106 four-way valve 107 outdoor heat exchanger 108 outdoor fan 109 outdoor pressure reducing device 110 accumulator 111 first compressor suction pipe 112 second Compressor intake pipe 113 First branched oil return pipe 114 Second branched oil return pipe 115 Low pressure gas pipe 116 Radiator 117 Refrigerant liquid pipe 118 Bypass pipe 119 Exhaust heat recovery heat exchanger 120 Exhaust heat recovery decompression device 121 Oil refrigerant heat exchanger 200 indoor unit 201 indoor heat exchanger 202 indoor fan 203 indoor decompression device 300 air conditioner

Claims (1)

An air conditioner that performs air conditioning by circulating a refrigerant by connecting a first compressor driven by a gas engine and a second compressor driven by an electric motor in parallel,
An oil separator is provided downstream from the confluence of the discharge pipes of the first compressor and the second compressor,
an oil return pipe connected to the bottom of the oil separator;
a first branched oil return pipe branched from the oil return pipe and connected to the suction pipe of the first compressor;
a second branch oil return pipe branched from the oil return pipe and connected to the suction pipe of the second compressor;
Furthermore, a bypass pipe connecting the refrigerant liquid pipe and the low pressure gas pipe upstream of the accumulator,
An air conditioner, wherein the oil return pipe and the bypass pipe are provided with a heat exchange part for exchanging heat between oil and refrigerant.

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