GB2571842A

GB2571842A - Air conditioning device

Info

Publication number: GB2571842A
Application number: GB1905450.1A
Authority: GB
Inventors: Masuda Tetsuya; Hasegawa Hiroshi; Suito Kazuaki
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2016-11-24
Filing date: 2017-11-21
Publication date: 2019-09-11
Anticipated expiration: 2037-11-21
Also published as: GB201905450D0; GB2571842B; WO2018097124A1; DE112017005948T5; JP6854455B2; JPWO2018097124A1

Abstract

Provided is an air conditioning device which has a plurality of compressors connected in parallel, and can be operated at high efficiency regardless of the magnitude of a required load. This air conditioning device is provided with: a first compressor 101 driven by a gas engine 103; a second compressor 102 connected to the first compressor 101 in parallel and having a different capacity from the first compressor 101; a refrigerant tube 115 provided between an indoor heat exchanger 201 and an outdoor heat exchanger 106; a bypass tube 114 connecting the refrigerant tube 115, a suction tube 134 of the first compressor, and a suction tube 135 of the second compressor; an exhaust heat recovery heat exchanger 112 which is provided to the bypass tube 114 and transfers the exhaust heat of the gas engine 103 to the refrigerant; a switching means comprising a first opening/closing means 119 and a second opening/closing means 120, which are disposed downstream from the exhaust heat recovery heat exchanger 112, and are capable of selectively supplying the refrigerant to the first compressor 101 or the second compressor 102; and an inflow prevention means comprising a first check valve 121 provided upstream from a connection part 136 between the suction tube 134 of the first compressor and the bypass tube 114, and a second check valve 122, provided upstream from a connection part 137 between the second compressor 102 and the bypass tube 114.

Description

[Document Name] Description [Title of Invention] AIR CONDITIONING DEVICE [Technical Field] [0001]

The present invention relates to an air conditioning device including a compressor that is driven by a gas engine .

[Background Art] [0002]

Heretofore, there has been proposed an air conditioning device including a plurality of compressors having different capacities in an outdoor unit, and including a plurality of driving means that are provided correspondingly to the respective compressors, and control means that individually drives the plurality of compressors or drives the plurality of compressors in combination in accordance with a magnitude of a required load. (Patent Literature 1, for example).

[Citation List] [Patent Literature] [0003] [Patent Literature 1] Japanese Patent Laid-Open No. 2003

56931 [Summary of Invention] [Technical Problem] [0004]

However, when heating of a refrigerant is performed by using exhaust heat of a gas engine while pumping up heat from outdoor air in an outdoor heat exchanger at a heating operation time, a pressure of the refrigerant to be sucked by two compressors becomes equal to a pressure of the outdoor heat exchanger in which a temperature of air or gas engine cooling water that is a heat absorption source is lower, and in an exhaust heat using heat exchanger, a temperature difference from the temperature of the engine cooling water that is the heat absorption source increases.

In general, an outdoor air temperature at a heating time is from about 0 to 10°C, so that a vaporization pressure of the refrigerant is required to be set to a saturated vapor pressure at about -5 to 5°C, in order to pump up the heat from air in the outdoor heat exchanger. On the other hand, the engine cooling water temperature is from about 60 to 70°C, so that it is possible to pump up the heat in the exhaust heat using heat exchanger even when the vaporization pressure of the refrigerant is sufficiently raised with respect to the pressure in the outdoor heat exchanger, but in a configuration in which a refrigerant outlet of the outdoor heat exchanger and an outlet of the exhaust heat using heat exchanger join each other in a suction pipe of the compressor, the vaporization pressure of the refrigerant cannot be set individually in the outdoor heat exchanger and the exhaust heat using heat exchanger. Consequently, the vaporization pressure of the refrigerant of the exhaust heat using heat exchanger is also required to be set to the saturated vapor pressure at about -5 to 5°C. In the exhaust heat using heat exchanger, a temperature difference between the heat absorption source and the refrigerant is large, that is, the vaporization pressure of the refrigerant does not become a pressure that is suitable at the temperature of the heat absorption source, and vaporization is performed by wastefully lowering the pressure, so that there has been the problem that a compression power to raise the pressure by the compressor is excessively required and an efficient operation is not enabled.

The present invention is intended to solve the above described conventional problem, and has an object to provide an air conditioning device that reduces energy consumption especially in a case where a required air conditioning load is high at the heating time.

[Solution to Problem] [0005]

In this description, all contents of Japanese Patent Application No. 2016-228142 filed in November 24, 2016 are included.

In order to solve the above described problem, an air conditioning device of the present invention includes a first compressor that is driven by a gas engine, a second compressor that is connected in parallel with the first compressor and is different in capability from the first compressor, a refrigerant liquid pipe that is provided between an indoor heat exchanger and an outdoor heat exchanger, a bypass pipe that connects the refrigerant liquid pipe, a suction pipe of the first compressor and a suction pipe of the second compressor, an exhaust heat recovering heat exchanger that is provided in the bypass pipe and transfers exhaust heat of the gas engine to a refrigerant, switching means that is located downstream of the exhaust heat recovering heat exchanger and is capable of selectively supplying the refrigerant to the first compressor or the second compressor, and inflow preventing means that is provided either one or both of upstream of a connection section of the suction pipe of the first compressor and the bypass pipe and upstream of a connection section of the second compressor and the bypass pipe and that prevents passage of the refrigerant which flows in from the bypass pipe.

Consequently, at a heating operation time, the refrigerant which vaporizes in the outdoor heat exchanger and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger do not join each other, and are sucked by the separate compressors. Heat absorption sources of the outdoor heat exchanger and the exhaust heat recovering heat exchanger are air (outside air) and engine exhaust heat cooling water respectively, and a temperature of engine cooling water is a high temperature with respect to an outside air temperature, so that a vaporization pressure of the refrigerant in the exhaust heat recovering heat exchanger becomes high, with respect to a vaporization pressure of the refrigerant in the outdoor heat exchanger.

[Advantageous Effect of Invention] [0006]

In an air conditioning device of the present invention, it becomes possible to set pressures of a refrigerant which vaporizes in an outdoor heat exchanger and a refrigerant which vaporizes in an exhaust heat recovering heat exchanger properly in accordance with temperatures of respective heat absorption sources.

The pressure of the refrigerant which vaporizes in the exhaust heat recovering heat exchanger can be set to be higher than a pressure of a refrigerant which vaporizes in the outdoor heat exchanger, so that power of a compressor that sucks the refrigerant which is vaporized in the exhaust heat recovering heat exchanger is reduced, that is, energy which is consumed by the air conditioning device at a heating time can be decreased.

[Brief Description of Drawings] [0007] [Figure 1] Figure 1 is a refrigerating cycle diagram of an air conditioning device in an embodiment of the present invention.

[Figure 2] Figure 2 illustrates an optimal operation ratio based on magnitudes of loads of a gas engine drive compressor and an electric motor drive compressor in the air conditioning device in the embodiment.

[Figure 3] Figure 3 is a Molier chart comparing a conventional refrigerating cycle operating point and a refrigerating cycle operating point in the present embodiment.

[Description of Embodiments] [0008]

An air conditioning device according to a first aspect of the present invention includes a first compressor that is driven by a gas engine, a second compressor that is connected in parallel with the first compressor and is different in capability from the first compressor, a refrigerant liquid pipe that is provided between an indoor heat exchanger and an outdoor heat exchanger, a bypass pipe that connects the refrigerant liquid pipe, a suction pipe of the first compressor and a suction pipe of the second compressor, an exhaust heat recovering heat exchanger that is provided in the bypass pipe and transfers exhaust heat of the gas engine to a refrigerant, switching means that is located downstream of the exhaust heat recovering heat exchanger and is capable of selectively supplying the refrigerant to the first compressor or the second compressor, and inflow preventing means that is located at either one or both of upstream of a connection section of the suction pipe of the first compressor and the bypass pipe and upstream of a connection section of the second compressor and the bypass pipe and that prevents passage of the refrigerant which flows in from the bypass pipe.

Consequently, at a heating operation time, the refrigerant which vaporizes in the outdoor heat exchanger and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger do not join each other, and are sucked by the separate compressors. Heat absorption sources of the outdoor heat exchanger and the exhaust heat recovering heat exchanger are air (outside air) and engine exhaust heat cooling water respectively, and a temperature of engine cooling water is a high temperature with respect to an outside air temperature, so that a vaporization pressure of the refrigerant in the exhaust heat recovering heat exchanger becomes high, with respect

- 8 to a vaporization pressure of the refrigerant in the outdoor heat exchanger.

It becomes possible to set pressures of the refrigerant which vaporizes in the outdoor heat exchanger and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger properly in accordance with temperatures of the respective heat absorption sources.

The pressure of the refrigerant which vaporizes in the exhaust heat recovering heat exchanger can be set to be higher than the pressure of the refrigerant which vaporizes in the outdoor heat exchanger, so that power of the compressor which sucks the refrigerant which is vaporized in the exhaust heat recovering heat exchanger is reduced, that is, energy which is consumed by the air conditioning device at a heating time can be decreased. [0009]

In the air conditioning device according to a second aspect of the present invention, the bypass pipe branches into a first branch pipe and a second branch pipe downstream of the exhaust heat recovering heat exchanger, the first branch pipe is connected to the suction pipe of the first compressor, the second branch pipe is connected to the suction pipe of the second compressor, and the switching means includes first on-off means provided in the first branch pipe and second on-off means provided in the second branch pipe.

Also in this aspect of the invention, it becomes possible to set the pressures of the refrigerant which vaporizes in the outdoor heat exchanger and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger properly in accordance with the temperatures of the respective heat absorption sources.

The pressure of the refrigerant which vaporizes in the exhaust heat recovering heat exchanger can be set to be higher than the pressure of the refrigerant which vaporizes in the outdoor heat exchanger, so that the power of the compressor that sucks the refrigerant which is vaporized in the exhaust heat recovering heat exchanger is reduced, that is, the energy which is consumed by the air conditioning device at the heating time can be decreased.

[0010]

In the air conditioning device according to a third aspect of the invention, the inflow preventing means is a check valve.

According to this aspect of the invention, when the refrigerant which vaporizes in the outdoor heat exchanger and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger do not join each other, and are sucked by the separate compressors, the switching means may only be switched to supply the refrigerant which passes through the exhaust heat recovering heat exchanger to the first compressor or the second compressor.

In this case, the refrigerant that passes through the outdoor heat exchanger has a lower pressure than the refrigerant that passes through the exhaust heat recovering heat exchanger, so that when the check valve is provided as the inflow preventing means, the refrigerant that passes through the outdoor heat exchanger flows into the compressor on a side into which the refrigerant that passes through the exhaust heat recovering heat exchanger does not flow.

Furthermore, cost can be reduced by the check valve which is more inexpensive than an on-off valve.

[0011]

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited by this embodiment.

[0012] (Embodiment)

Figure 1 illustrates a circuit diagram of an air conditioning device 300 in an embodiment of the present invention .

The air conditioning device 300 according to the embodiment of the present invention includes an outdoor unit 100 and an indoor unit 200.

The outdoor unit 100 includes a gas engine 103 with gas as a driving source, a first compressor 101 that obtains a driving force from the gas engine 103 to compress a refrigerant, and a second compressor 102 with an electric motor as the driving source. As the first compressor 101, a compressor having a larger capacity than the second compressor 102 is selected.

Note that the second compressor 102 may be a compressor that obtains the driving force from the gas engine to compress the refrigerant.

[0013]

A junction discharge pipe 123 where a discharge pipe of the first compressor 101 and a discharge pipe of the second compressor 102 join each other is equipped with an oil separator 104. The oil separator 104 separates oil contained in discharge refrigerant gas of the first compressor 101 and the second compressor 102.

The oil separated in the oil separator 104 is returned to a suction pipe 134 of the first compressor and a suction pipe 135 of the second compressor through an oil return pipe not illustrated.

A four-way valve 105 is located downstream of the oil separator 104. The four-way valve 105 is for switching a refrigerating cycle between cooling and heating. Note that in Figure 1, a heating operation is achieved when the refrigerant is passed along a solid line, and a cooling operation is achieved when the refrigerant is passed along a dotted line.

[0014]

The junction discharge pipe 123 is connected to one end of an indoor heat exchanger 201 in the indoor unit 200. The indoor unit 200 includes the indoor heat exchanger 201, an indoor blower fan 202 and an indoor decompression device 203.

A refrigerant pipe 130 that is connected to the other end of the indoor heat exchanger 201 is connected to one end of an outdoor heat exchanger 106 in the outdoor unit 100 via the indoor decompression device 203 and an outdoor decompression device 108.

In the refrigerant pipe 130, the pipe between the indoor decompression device 203 and the outdoor decompression device 108 is defined as a refrigerant liquid pipe 115.

A radiator 111 is provided at a leeward side of the outdoor heat exchanger 106, and heat radiation of engine cooling water is performed by an outdoor fan 107.

[0015]

A suction pipe 133 connected to the other end of the outdoor heat exchanger 106 branches into the suction pipe 134 of the first compressor and the suction pipe 135 of the second compressor via the four-way valve 105. The suction pipe 134 of the first compressor is connected to a suction port of the first compressor 101 via an accumulator 109. The suction pipe 135 of the second compressor is connected to a suction port of the second compressor 102 via an accumulator 110.

[0016]

The air conditioning device 300 includes a bypass pipe 114 that connects the refrigerant liquid pipe 115, the suction pipe 134 of the first compressor and the suction pipe 135 of the second compressor.

The bypass pipe 114 includes a decompression device 113. An exhaust heat recovering heat exchanger 112 that transfers exhaust heat of the gas engine 103 to the refrigerant is provided downstream of the decompression device 113. Since the decompression device 113 and the exhaust heat recovering heat exchanger 112 are provided, the refrigerant in the air conditioning device 300 also can absorb heat from the engine cooling water at a heating time.

[0017]

The bypass pipe 114 branches into a first branch pipe 117 and a second branch pipe 118 in a bypass branching section 116 located downstream of the exhaust heat recovering heat exchanger 112. The first branch pipe 117 is connected to the suction pipe 134 of the first compressor. The second branch pipe 118 is connected to the suction pipe 135 of the second compressor. The first branch pipe 117 includes first onoff means 119. The second branch pipe 118 includes second on-off means 120.

In the first on-off means 119, for example, an on off valve is usable.

In the second on-off means 120, for example, an onoff valve is usable.

[0018]

The first on-off means 119 and the second on-off means 120 constitute switching means.

By controlling opening and closing of the first onoff means 119 and the second on-off means 120, the refrigerant that passes through the exhaust heat recovering heat exchanger 112 can selectively be supplied to the first compressor 101 or the second compressor 102. [0019]

Note that as the switching means, for example, a switching valve such as a three-way valve may be used in the bypass branching section 116.

Furthermore, for example, the switching means may include only one of the first on-off means 119 and the second on-off means 120.

[0020]

A first check valve 121 is disposed upstream of a connection section 136 of the suction pipe 134 of the first compressor and the first branch pipe 117. A second check valve 122 is disposed upstream of a connection section 137 of the suction pipe 135 of the second compressor and the second branch pipe 118.

[0021]

The first check valve 121 and the second check valve 122 constitute inflow preventing means.

By this first check valve 121 and the second check valve 122, the refrigerant supplied from the exhaust heat recovering heat exchanger 112 and having a higher pressure than the refrigerant supplied from the outdoor heat exchanger 106 can be prevented from flowing backward to a side of the lower-pressure refrigerant supplied from the outdoor heat exchanger 106.

[0022]

Any inflow preventing means may be used as long as the refrigerant flowing from the first branch pipe 117 to the suction pipe 134 of the first compressor can be prevented from flowing backward to the suction pipe 133. Furthermore, any inflow preventing means may be used as long as the refrigerant flowing from the second branch pipe 118 to the suction pipe 135 of the second compressor can be prevented from flowing backward to the suction pipe 133 .

In the inflow preventing means, for example, a first on-off valve may be used in place of the first check valve 121, and a second on-off valve may be used in place of the second check valve 122.

Furthermore, for example, a switching valve such as a three-way valve may be used as the inflow preventing means in a region where three pipes of the suction pipe 133, the suction pipe 134 of the first compressor and the suction pipe 135 of the second compressor are connected.

[0023]

Next, operations of the outdoor unit 100 and the indoor unit 200 will be described separately in accordance with magnitudes of loads which are reguired, in the cooling operation, the heating operation and the respective operation states, with use of Figure 1.

[0024] (Cooling operation low load time)

At a low load time in the cooling operation, only the second compressor 102 with the electric motor as the driving source is driven. The first on-off means 119 and the second on-off means 120 are closed. The four-way valve 105 is set to pass the refrigerant along a dotted line .

[0025]

The high-temperature and high-pressure refrigerant which is compressed by the second compressor 102 flows into the oil separator 104. A gas refrigerant with high purity from which oil is separated in the oil separator 104 passes through the four-way valve 105 and enters the outdoor heat exchanger 106. The gas refrigerant exchanges heat with outside air, radiates heat, condenses thereafter in the outdoor heat exchanger 106, and becomes a high-pressure liquid refrigerant to pass through the outdoor decompression device 108 to be supplied to the indoor unit 200.

The high-pressure liquid refrigerant that enters the indoor unit 200 is decompressed in the indoor decompression device 203 to be in a gas-liquid two-phase state, and flows into the indoor heat exchanger 201. The refrigerant in the gas-liquid two-phase state exchanges heat with air in a space which is an air conditioning target to absorb heat and vaporize thereafter in the indoor heat exchanger 201, and becomes a gas refrigerant to flow out of the indoor unit 200.

[0026]

The gas refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The gas refrigerant which flows into the outdoor unit 100 passes through the four-way valve 105 and the accumulator 110 to return to the second compressor 102, and repeats the above described process.

[0027] (Cooling operation medium load time)

At a medium load time in the cooling operation, the first compressor 101 having the gas engine 103 as the driving source is driven. The first on-off means 119 and the second on-off means 120 are closed. The four-way valve 105 is set to pass the refrigerant along the dotted line .

[0028]

The high-temperature and high-pressure refrigerant which is compressed by the first compressor 101 flows into the oil separator 104. The gas refrigerant with high purity from which oil is separated in the oil separator 104 passes through the four-way valve 105 and enters the outdoor heat exchanger 106. The gas refrigerant exchanges heat with outside air, radiates heat, condenses thereafter in the outdoor heat exchanger 106, and becomes a high-pressure liquid refrigerant to pass through the outdoor decompression device 108 to be supplied to the indoor unit 200.

[0029]

The gas refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The gas refrigerant which flows into the outdoor unit 100 passes through the four-way valve 105 and the accumulator 109 to return to the first compressor 101, and repeats the above described process.

Note that exhaust heat which is generated in the gas engine 103 is carried to the radiator 111 by engine cooling water and a pump not illustrated, exchanges heat with outside air, and returns to the gas engine 103 again.

[0030] (Cooling operation high load time)

At a high load time in the cooling operation, both of the first compressor 101 having the gas engine 103 as the driving source, and the second compressor 102 having the electric motor as the driving source are driven. The first on-off means 119 and the second on-off means 120 are closed. The four-way valve 105 is set to pass the refrigerant along the dotted line.

[0031]

The high-temperature and high-pressure refrigerant which is compressed by the first compressor 101 and the second compressor 102 flows into the oil separator 104. The refrigerant which flows into the oil separator 104 becomes a gas refrigerant with high purity from which oil is separated, passes through the four-way valve 105 and enters the outdoor heat exchanger 106. The gas refrigerant exchanges heat with outside air, radiates heat, condenses thereafter in the outdoor heat exchanger 106, and becomes a high-pressure liquid refrigerant to pass through the outdoor decompression device 108 to be supplied to the indoor unit 200.

[0032]

The gas refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The gas refrigerant which flows into the outdoor unit 100 flows through the four-way valve 105 and the suction pipe 134 of the first compressor or the suction pipe 135 of the second compressor. The gas refrigerant which flows through the suction pipe 134 of the first compressor passes through the accumulator 109 to return to the first compressor 101, and repeats the above described process. The gas refrigerant which flows through the suction pipe 135 of the second compressor passes through the accumulator 110 to return to the second compressor 102, and repeats the above described process.

Note that exhaust heat which is generated in the gas engine 103 is carried to the radiator 111 by the engine cooling water and the pump not illustrated, exchanges heat with outside air and returns to the gas engine 103 again .

[0033] (Heating operation low load time)

At a low load time in the heating operation, only the second compressor 102 having the electric motor as the driving source is driven. The first on-off means 119 and the second on-off means 120 are closed. The four-way valve 105 is set to pass the refrigerant along the solid line .

[0034]

The high-temperature and high-pressure refrigerant which is compressed by the second compressor 102 flows into the oil separator 104. A gas refrigerant with high purity from which oil is separated in the oil separator 104 passes through the four-way valve 105 and is supplied to the indoor unit 200.

The high-temperature and high-pressure gas refrigerant which enters the indoor unit 200 flows into the indoor heat exchanger 201, exchanges heat with air in a space which is an air conditioning target to radiate heat, condenses thereafter, and becomes a liquid refrigerant to flow out of the indoor unit 200 through the indoor decompression device 203.

[0035]

The liquid refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The liquid refrigerant which flows into the outdoor unit 100 is decompressed in the outdoor decompression device 108 to be in a gas-liquid two-phase state and flows into the outdoor heat exchanger 106. The refrigerant in the gasliquid two-phase state exchanges heat with outside air to absorb heat and vaporize thereafter in the outdoor heat exchanger 106, becomes a gas refrigerant to pass through the four-way valve 105 and the accumulator 110 to return to the second compressor 102, and repeats the above described process.

[0036] (Heating operation medium load time)

At a medium load time in the heating operation, the first compressor 101 having the gas engine 103 as the driving source is driven. The first on-off means 119 and the second on-off means 120 are closed. The four-way valve 105 is set to pass the refrigerant along the solid line .

[0037]

The high-temperature and high-pressure refrigerant which is compressed by the first compressor 101 flows into the oil separator 104. A gas refrigerant with high purity from which oil is separated in the oil separator 104 is supplied to the indoor unit 200 through the fourway valve 105 .

The high-temperature and high-pressure gas refrigerant which enters the indoor unit 200 flows into the indoor heat exchanger 201, exchanges heat with air in a space which is an air conditioning target to radiate heat and condense thereafter, and becomes a liquid refrigerant to flow out of the indoor unit 200 through the indoor decompression device 203.

[0038]

The liquid refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The liquid refrigerant which flows into the outdoor unit 100 is decompressed in the outdoor decompression device 108 to be in a gas-liquid two-phase state and flows into the outdoor heat exchanger 106. The refrigerant in the gasliquid two-phase state exchanges heat with outside air to absorb heat and vaporize thereafter, and becomes a gas refrigerant. Thereafter, the gas refrigerant passes through the four-way valve 105 and the accumulator 109, returns to the first compressor 101, and repeats the above described process.

[0039] (Heating operation extremely low temperature time)

At an extremely low temperature time in the heating operation, the first compressor 101 with the gas engine

103 as the driving source and the second compressor 102 with the electric motor as the driving source are driven.

The first on-off means 119 and the second on-off means

120 are opened, and the outdoor decompression device 108 is closed. The four-way valve 105 is set to pass the refrigerant along the solid line.

[0040]

The high-temperature and high-pressure refrigerant which is compressed by the first compressor 101 and the second compressor 102 flows into the oil separator 104. A gas refrigerant with high purity from which oil is separated in the oil separator 104 is supplied to the indoor unit 200 through the four-way valve 105.

[0041]

The liquid refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The liquid refrigerant which flows into the outdoor unit 100 flows through the bypass pipe 114, and is decompressed in the decompression device 113 to be in a gas-liquid twophase state, and flows into the exhaust heat recovering heat exchanger 112. The refrigerant in the gas-liquid two-phase state exchanges heat with engine cooling water to absorb heat and vaporize thereafter, and becomes a medium-temperature and medium-pressure gas refrigerant. Thereafter, the medium-temperature and medium-pressure gas refrigerant is branched in the bypass branching section 116, and the refrigerant partially flows through the first branch pipe 117, returns to the first compressor 101 through the first on-off means 119 and the accumulator 109, and repeats the above described process. The remaining refrigerant flows through the second branch pipe 118, returns to the second compressor 102 through the second on-off means 120 and the accumulator 110, and repeats the above determined process.

At this time, the outdoor decompression device 108 is closed, so that the refrigerant does not flow into the outdoor heat exchanger 106. This is to prevent frost from forming on the outdoor heat exchanger 106 because an outside air temperature is low.

[0042] (Heating operation high load time)

At a high load time in the heating operation, the first compressor 101 with the gas engine 103 as the driving source, and the second compressor 102 with the electric motor as the driving source are driven. The first on-off means 119 is closed and the second on-off means 120 is opened. The four-way valve 105 is set to pass the refrigerant along the solid line.

[0043]

The high-temperature and high-pressure refrigerant which is compressed by the first compressor 101 and the second compressor 102 flows into the oil separator 104. The refrigerant which flows into the oil separator 104 becomes a gas refrigerant with high purity from which oil is separated, passes through the four-way valve 105, and is supplied to the indoor unit 200.

[0044]

The liquid refrigerant which flows out of the indoor unit 200 returns to the outdoor unit 100 again. The liquid refrigerant which flows into the outdoor unit 100 partially flows into the bypass pipe 114. The remaining liquid refrigerant which does not flow into the bypass pipe 114 is decompressed in the outdoor decompression device 108 to be in a gas-liguid two-phase state and flows into the outdoor heat exchanger 106. The refrigerant in the gas-liquid two-phase state exchanges heat with outside air to absorb heat and vaporize thereafter, and becomes a low-temperature and lowpressure gas refrigerant. Thereafter, the gas refrigerant passes through the four-way valve 105 and the accumulator 109, and returns to the first compressor 101. [0045]

The liquid refrigerant which flows into the bypass pipe 114 is decompressed in the decompression device 113, is in the gas-liquid two-phase state and flows into the exhaust heat recovering heat exchanger 112. The refrigerant in the gas-liquid two-phase state which flows into the exhaust heat recovering heat exchanger 112 absorbs heat from the engine cooling water not illustrated, vaporizes thereafter, and becomes a mediumtemperature and medium-pressure gas refrigerant. The medium-temperature and medium-pressure gas refrigerant passes through the bypass branching section 116 and the second branch pipe 118 and returns to the second compressor 102. Here, the first on-off means 119 is closed, so that the medium-temperature and mediumpressure gas refrigerant flows through the second branch pipe 118 and the suction pipe 135 of the second compressor, and the second check valve 122 is provided in the suction pipe 135 of the second compressor, so that the medium-temperature and medium-pressure gas refrigerant is not sucked by the first compressor 101. [0046]

Accordingly, the low-temperature and low-pressure gas refrigerant which is vaporized in the outdoor heat exchanger 106 returns to the first compressor 101, and is compressed to be a high-temperature and high-pressure gas refrigerant. The medium-temperature and medium-pressure gas refrigerant which is vaporized in the exhaust heat recovering heat exchanger 112 returns to the second compressor 102, and is compressed to be the hightemperature and high-pressure gas refrigerant, and the above described process is repeated.

[0047]

The operations at the heating extremely low temperature time and at the heating high load time are divided in accordance with the outside air temperature. For example, in a case where the outside air temperature is below 0°C, there is a high possibility of frost formed on the outdoor heat exchanger 106, so that an operation pattern at the heating extremely low temperature time is selected, and frost formation is avoided by performing heat absorption only from the exhaust heat recovering heat exchanger 112 without performing heat absorption in the outdoor heat exchanger 106. When the outside air temperature is 0°C or higher, an operation pattern at the heating high load time is selected, and heat absorption in the outdoor heat exchanger 106 and heat absorption in the exhaust heat recovering heat exchanger 112 are used in combination.

[0048]

As illustrated in Figure 2, it is found that in the above described air conditioning device 300, only the second compressor 102 that is driven by the electric motor is driven when the air conditioning load is small, only the first compressor 101 that is driven by the gas engine is driven when the air conditioning load is about medium, and when the air conditioning load is high, the first compressor 101 which is driven by the gas engine is driven at a maximum output, and an insufficient amount is made up for by the second compressor 102 which is driven by the electric motor, whereby the highest energy efficiency is obtained, from test calculation result, and actual machine evaluation result by the inventors.

In a conventional air conditioning device, similar description has been made, and in the conventional air conditioning device, in the case of the air conditioning load being high in the heating operation, heating of the refrigerant is performed by using exhaust heat of the gas engine while pumping up heat from outdoor air in the outdoor heat exchanger. A pressure of the refrigerant to be sucked by two compressors becomes equal to a pressure of the outdoor heat exchanger in which a temperature of a heat absorption source is lower, the heat absorption source being air, or gas engine cooling water, and in an exhaust heat using heat exchanger, a temperature difference of the refrigerant from the temperature of the engine cooling water that is the heat absorption source increases .

[0049]

In general, an outdoor air temperature at a heating time is from about 0 to 10°C, so that a vaporization pressure of the refrigerant is required to be set to a saturated vapor pressure at about -5 to 5°C, in order to pump up the heat from air in the outdoor heat exchanger. On the other hand, the engine cooling water temperature is from about 60 to 70°C, so that it is possible to pump up the heat in the exhaust heat using heat exchanger even when the vaporization pressure of the refrigerant is sufficiently raised with respect to the pressure in the outdoor heat exchanger. However, in a configuration in which a refrigerant outlet of the outdoor heat exchanger and an outlet of the exhaust heat using heat exchanger join each other in a suction pipe of the compressor, the vaporization pressure of the refrigerant cannot be set individually in the outdoor heat exchanger and the exhaust heat using heat exchanger. Consequently, in the configuration in which the refrigerant outlet of the outdoor heat exchanger and the outlet of the exhaust heat using heat exchanger join each other in the suction pipe of the compressor, the vaporization pressure of the refrigerant of the exhaust heat using heat exchanger is also required to be set to the saturated vapor pressure at about -5 to 5°C. In the exhaust heat using heat exchanger, a temperature difference between the heat absorption source and the refrigerant is large, that is, the vaporization pressure of the refrigerant does not become a pressure that is suitable at the temperature of the heat absorption source, and vaporization is performed by wastefully lowering the pressure, so that there has been the problem that a compression power to raise the pressure by the compressor again is excessively required and an efficient operation is not enabled.

[0050]

In the air conditioning device 300 according to the present embodiment, in the case of the air conditioning load being high at the heating operation time, a lowtemperature and low-pressure gas refrigerant is compressed to a high temperature and a high pressure by the first compressor 101 which is driven by the gas engine, and a medium-temperature and medium-pressure gas refrigerant is compressed to a high temperature and a high pressure by the second compressor 102 which is driven by the electric motor. Consequently, as illustrated in a Molier chart of the present embodiment in Figure 3, a suction pressure of the second compressor 102 which is driven by the electric motor is higher than a suction pressure in a case of a conventional example, and a compression ratio (high pressure/low pressure) of the second compressor 102 which is driven by the electric motor becomes low, so that energy that is consumed by the second compressor 102 which is driven by the electric motor can be decreased as compared with the conventional example .

[0051]

Note that in the present embodiment, at the high load time in the heating operation, the low-temperature and low-pressure gas refrigerant is sucked by the first compressor 101 which is driven by the gas engine, and the medium-temperature and medium-pressure gas refrigerant is sucked by the second compressor 102 which is driven by the electric motor, but the low-temperature and lowpressure gas refrigerant may be sucked by the second compressor 102 which is driven by the electric motor, and the medium-temperature and medium-pressure gas refrigerant may be sucked by the first compressor 101 which is driven by the gas engine. Furthermore, both the first and second compressors may be driven by the gas engine .

[0052]

With respect to the present embodiment, the refrigerant liquid pipe 115 has two bypass pipes therefrom, two exhaust heat recovering heat exchangers are provided in parallel, one of the heat exchangers is connected to a suction pipe of a compressor which is driven by a gas engine, the other heat exchanger is connected to a suction pipe of a compressor which is driven by an electric motor, and an on-off valve is located upstream of a connection section of the bypass pipe in each of the suction pipes of the compressors, and in this configuration, similarly to the present embodiment, it is possible to individually set a suction pressure of a refrigerant in the first compressor and a suction pressure of a refrigerant in the second compressor .

However, in the above described example, the exhaust heat recovering heat exchangers are provided in parallel, so that it is necessary to provide two systems of engine cooling water circuits which are respective heat absorption sources, and the cooling water circuits become complicated. Furthermore, when both the exhaust heat recovering heat exchangers are simultaneously used (in the case of the heating operation extremely low temperature time in the present embodiment) and when excess or shortage of an amount of the cooling water occurs in the one exhaust heat recovering heat exchanger, the other exhaust heat recovering heat exchanger is thus influenced, and the excess or shortage of the amount of the cooling water also occurs in the other than exhaust heat recovering heat exchanger.

For example, when the excessive cooling water is supplied to the one exhaust heat recovering heat exchanger, the amount of the cooling water for the other exhaust heat recovering heat exchanger runs short, and the exhaust heat recovering heat exchanger in which the amount of the cooling water runs short has risk that vaporization of the refrigerant is not sufficiently performed, liquid back occurs, this results in a failure of the compressor. Furthermore, in the exhaust heat recovering heat exchanger in which an excessive amount of the cooling water is supplied, when the refrigerant is excessively heated and a discharge temperature of the refrigerant becomes high, oil that covers lubrication of the compressor deteriorates, and when the electric motor is a driving source, for example, the motor is damaged, thereby causing problem in reliability.

Consequently, when the suction pressure of the refrigerant in the first compressor 101 and the suction pressure in the second compressor 102 are individually set, it is preferable that as in the present embodiment, one exhaust heat recovering heat exchanger 112 is provided, and a flow path of the refrigerant that passes through the exhaust heat recovering heat exchanger 112 is branched and connected to the first compressor 101 and the second compressor 102 respectively.

[0053]

As described above, according to the present embodiment, there are included the first compressor 101 that is driven by the gas engine 103, the second compressor 102 that is connected in parallel with the first compressor 101 and is different in capability from the first compressor 101, the refrigerant liquid pipe 115 that is provided between the indoor heat exchanger 201 and the outdoor heat exchanger 106, the bypass pipe 114 that connects the refrigerant liquid pipe 115, the suction pipe 134 of the first compressor and the suction pipe 135 of the second compressor, the exhaust heat recovering heat exchanger 112 that is provided in the bypass pipe 114 and transfers exhaust heat of the gas engine 103 to a refrigerant, the switching means including the first on-off means 119 and the second on off means 120 which are located downstream of the exhaust heat recovering heat exchanger 112 and are to selectively supply the refrigerant to the first compressor 101 or the second compressor 102, and the inflow preventing means including the first check valve 121 that is located upstream of the connection section 136 of the suction pipe 134 of the first compressor and the bypass pipe 114, and the second check valve 122 that is located upstream of the connection section 137 of the second compressor 102 and the bypass pipe 114.

Consequently, in the case of the air conditioning load being high at the heating operation time, the lowtemperature and low-pressure gas refrigerant is compressed to the high temperature and the high pressure by the first compressor 101 that is driven by the gas engine 103, and the medium-temperature and mediumpressure gas refrigerant is compressed to the high temperature and the high pressure by the second compressor 102 that is driven by the electric motor, so that it is possible to set pressures of a refrigerant which vaporizes in the outdoor heat exchanger 106 and a refrigerant which vaporizes in the exhaust heat recovering heat exchanger 112 properly in accordance with temperatures of respective heat absorption sources.

That is, the pressure of the refrigerant which vaporizes in the exhaust heat recovering heat exchanger 112 can be set to be higher than the pressure of the refrigerant which vaporizes in the outdoor heat exchanger, so that power of the compressor that sucks the refrigerant which is vaporized in the exhaust heat recovering heat exchanger 112 is reduced, that is, energy which is consumed by the air conditioning device 300 at a heating time can be decreased.

[0054]

Furthermore, according to the present embodiment, the bypass pipe 114 branches into the first branch pipe 117 and the second branch pipe 118 downstream of the exhaust heat recovering heat exchanger 112, the first branch pipe 117 is connected to the suction pipe 134 of the first compressor, the second branch pipe 118 is connected to the suction pipe 135 of the second compressor, and the switching means includes the first on-off means 119 provided in the first branch pipe 117 and the second on-off means 120 provided in the second branch pipe 118.

Also in this aspect of the invention, it becomes possible to set the pressures of the refrigerant which vaporizes in the outdoor heat exchanger 106 and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger 112 properly in accordance with the temperatures of the respective heat absorption sources .

The pressure of the refrigerant which vaporizes in the exhaust heat recovering heat exchanger 112 can be set to be higher than the pressure of the refrigerant which vaporizes in the outdoor heat exchanger 106, so that the power of the compressor that sucks the refrigerant which is vaporized in the exhaust heat recovering heat exchanger 112 is reduced, that is, the energy which is consumed by the air conditioning device 300 at the heating time can be decreased.

[0055]

In addition, according to the present embodiment, the first check valve 121 and the second check valve 122 are used as the inflow preventing means.

Accordingly, when the refrigerant which vaporizes in the outdoor heat exchanger 106 and the refrigerant which vaporizes in the exhaust heat recovering heat exchanger 112 do not join each other, and are sucked by the separate compressors, the first on-off means 119 and the second on-off means 120 as the switching means may only be switched to supply the refrigerant that passes through the exhaust heat recovering heat exchanger 112 to the first compressor 101 or the second compressor 102.

In this case, the refrigerant that passes through the outdoor heat exchanger 106 has a lower pressure than the refrigerant that passes through the exhaust heat recovering heat exchanger 112, so that when the first check valve 121 and the second check valve 122 are provided, the refrigerant that passes through the outdoor heat exchanger 106 flows into the compressor on a side into which the refrigerant that passes through the exhaust heat recovering heat exchanger 112 does not flow.

Furthermore, cost can be reduced by using the first check valve 121 and the second check valve 122 more than by using an on-off valve.

[0056]

The present invention is described based on the present embodiments thus far, but the present invention is not limited by this embodiment. The embodiment only illustrates the modes of carrying out the present invention, so that arbitrary modifications and applications can be made within the range without departing from the gist of the present invention.

[Industrial Applicability] [0057]

The air conditioning device according to the present invention can be favorably used as an air conditioner capable of performing a highly efficient operation irrespective of an air conditioning load, by selecting driving sources of compressors in accordance with the air conditioning load.

[Reference Signs List] [0058]

100 Outdoor unit

101 First compressor

Second compressor

Gas engine

Outdoor decompression device

Exhaust heat recovering heat exchanger

Decompression device

Refrigerant liquid pipe

Bypass branching section

First branch pipe

Second branch pipe

First on-off valve (switching means)

Second on-off valve (switching means)

First check valve (inflow preventing means)

Second check valve (inflow preventing means

Suction pipe of first compressor

Suction pipe of second compressor

Indoor unit

Indoor decompression device

Air conditioning device

Claims

[Document Name] Claims [Claim 1]

An air conditioning device comprising:

a first compressor that is driven by a gas engine, a second compressor that is connected in parallel with the first compressor and is different in capability from the first compressor, a refrigerant liquid pipe that is provided between an indoor heat exchanger and an outdoor heat exchanger, a bypass pipe that connects the refrigerant liquid pipe, a suction pipe of the first compressor and a suction pipe of the second compressor, an exhaust heat recovering heat exchanger that is provided in the bypass pipe and transfers exhaust heat of the gas engine to a refrigerant, switching means that is located downstream of the exhaust heat recovering heat exchanger and is capable of selectively supplying the refrigerant to the first compressor or the second compressor, and inflow preventing means that is located at either one or both of upstream of a connection section of the suction pipe of the first compressor and the bypass pipe and upstream of a connection section of the second compressor and the bypass pipe and that prevents passage of the refrigerant which flows in from the bypass pipe. [Claim 2]

The air conditioning device according to claim 1, wherein the bypass pipe branches into a first branch pipe and a second branch pipe downstream of the exhaust heat recovering heat exchanger, the first branch pipe is connected to the suction pipe of the first compressor, the second branch pipe is connected to the suction pipe of the second compressor, and the switching means comprises first on-off means provided in the first branch pipe and second on-off means provided in the second branch pipe.

[Claim 3]

The air conditioning device according to claim 1 or 2, wherein the inflow preventing means is a check valve.

[Document Name] Abstract

In an air conditioning device in which a plurality of compressors are connected in parallel, there is provided an air conditioning device which is capable of performing a highly efficient operation irrespective of a magnitude of a required load.

There are included a first compressor 101 that is driven by a gas engine 103, a second compressor 102 that is connected in parallel with the first compressor 101 and is different in capability from the first compressor 101, a refrigerant liquid pipe 115 that is provided between an indoor heat exchanger 201 and an outdoor heat exchanger 106, a bypass pipe 114 that connects the refrigerant liquid pipe 115, a suction pipe 134 of the first compressor and a suction pipe 135 of the second compressor, an exhaust heat recovering heat exchanger 112 that is provided in the bypass pipe 114 and transfers exhaust heat of the gas engine 103 to a refrigerant, switching means including first on-off means 119 and second on-off means 120 which are located downstream of the exhaust heat recovering heat exchanger 112 and are to selectively supply the refrigerant to the first compressor 101 or the second compressor 102, and inflow preventing means including a first check valve 121 that is located upstream of a connection section 136 of the suction pipe 134 of the first compressor and the bypass pipe 114, and a second check valve 122 that is located

- 43 upstream of a connection section 137 of the second compressor 102 and the bypass pipe 114.