JP4013981B2 - Refrigeration air conditioner - Google Patents

Description

  The present invention relates to a refrigeration air conditioner using a refrigeration cycle using a supercritical refrigerant such as carbon dioxide.

  FIG. 19 is a refrigerant circuit diagram of a refrigeration apparatus using a conventional supercritical cycle. In the figure, the compressor 1 is driven by a prime mover 12 to compress the refrigerant. The compressed refrigerant gas is separated by the oil separator 2 from the oil contained in the refrigerant, cooled by the gas cooler 3, and expanded while driving the main shaft 11 connected to the compressor 1 through the expander 4. Then, the liquid is heated by the evaporator 5, separated by the accumulator 6, and then sucked into the compressor 1 again. Based on the refrigerant state quantity at the outlet side of the gas cooler detected by the temperature sensor 7 and the pressure sensor 8 provided in the connecting pipe between the gas cooler 3 and the expander 4, the calculation means 9 controls the expansion ratio control means 10 of the expander 4. The gas cooler outlet pressure is controlled to a predetermined pressure by controlling and changing the amount of refrigerant supplied to the expander (see, for example, Patent Document 1).

  Further, as a modified example, as shown in FIG. 20, a generator 13 or the like that can vary the load is disposed on the main shaft 11 of the expander 4, and the expander 4 is configured with a load that is independent from the compressor 1. Also shown is that the outlet pressure of the gas cooler 3 is controlled to a predetermined pressure by changing the number of revolutions.

  According to the publication, the reciprocating type is shown as the type of the expander, and the inflow and discharge of the fluid into the cylinder are controlled as the expander by controlling the opening timing of the valve.

Japanese Unexamined Patent Publication No. 2000-244103 (page 4-5, FIGS. 1 and 6)

  A reciprocating expander as in the prior art requires a complicated mechanism for opening and closing the valve in synchronism with the rotation of the main shaft or an electric switching valve and its control device. In order to avoid this, it is conceivable to use a type having a stroke volume and an internal volume ratio as an expander, such as a multi-vane type or a scroll type.

  In order to use an expander of this type in the refrigerant circuit configuration as shown in FIG. 19, in order to match the volume flow rate in the expander with the compressor side, a pre-expansion valve or bypass expansion is used instead of the expansion ratio control means. A valve is required. However, the pressure difference at the pre-expansion valve and the amount of bypass flow cannot be recovered.

  Further, when used in a refrigerant circuit configuration as shown in FIG. 20, the expander does not necessarily have to rotate at the same rotational speed as the compressor, so there is no need for flow rate matching, but when the recovered expansion power is taken out as electric energy. The amount of generator efficiency required is lost and the efficiency is reduced.

  The present invention has been made to solve such problems, and while using an expander that does not require a valve control mechanism such as a reciprocating type, while reducing the influence of power recovery loss due to flow rate matching and generator efficiency as much as possible. An object of the present invention is to obtain a highly efficient expansion power recovery supercritical refrigeration cycle apparatus with a refrigerant circuit configuration that also increases the efficiency on the compressor side.

A refrigerating and air-conditioning apparatus according to the present invention includes a plurality of compressors, a gas cooler that cools a high-pressure refrigerant compressed by the compressor, and an expander that extracts power by decompressing the gas cooled by the gas cooler. An evaporator that heats the refrigerant decompressed by the expander, and at least one of the compressors is a second compressor that is driven by being connected to a main shaft of the expander, and the expander and The second compressor has a stroke volume determined so that it is not necessary to perform pre-expansion at the expander inlet or the bypass of the expander under operating conditions with a large contribution to the annual average energy consumption efficiency , The second compressor is connected to the discharge side of the other compressor and has a plurality of operation modes.

  The refrigerating and air-conditioning apparatus according to the present invention includes a plurality of compressors, a gas cooler that cools the high-pressure refrigerant compressed by the compressor, and an expansion that extracts power by decompressing the gas cooled by the gas cooler. And an evaporator that heats the refrigerant decompressed by the expander, and at least one of the compressors is driven by the expansion power recovered by the expander and connected in series with the other compressor. The second compressor, a second gas cooler that is connected between the second compressor and the other compressor and cools the refrigerant, and bypasses the second gas cooler during heating operation among a plurality of operation modes. A flow path is provided.

A refrigerating and air-conditioning apparatus according to the present invention includes a plurality of compressors, a gas cooler that cools a high-pressure refrigerant compressed by the compressor, and an expander that extracts power by decompressing the gas cooled by the gas cooler. An evaporator that heats the refrigerant decompressed by the expander, and at least one of the compressors is a second compressor that is driven by being connected to a main shaft of the expander, and the expander and The second compressor has a stroke volume determined so that it is not necessary to perform pre-expansion at the expander inlet or the bypass of the expander under operating conditions with a large contribution to the annual average energy consumption efficiency , Since the second compressor is connected to the discharge side of the other compressor and has a plurality of operation modes, the COP and SEER are better and higher efficiency than the refrigerant circuit of the expander coaxial configuration, and the pre-expansion valve is It is possible to obtain a refrigeration and air conditioning device main next low cost. In addition, the flow rate matching with the compression side is performed using an expander with a fixed stroke volume and expansion volume ratio such as a multi-vane type or scroll type that does not have a complicated valve timing control mechanism like a reciprocating type expander. The non-recovery portion of the expansion power due to can be reduced compared to the coaxial case, and a highly efficient supercritical cycle refrigeration air conditioner can be obtained with a simple mechanism and configuration.

  The refrigerating and air-conditioning apparatus according to the present invention includes a plurality of compressors, a gas cooler that cools the high-pressure refrigerant compressed by the compressor, and an expansion that extracts power by decompressing the gas cooled by the gas cooler. And an evaporator that heats the refrigerant decompressed by the expander, and at least one of the compressors is driven by the expansion power recovered by the expander and connected in series with the other compressor. The second compressor, a second gas cooler that is connected between the second compressor and the other compressor and cools the refrigerant, and bypasses the second gas cooler during heating operation among a plurality of operation modes. Since the flow path is provided, a complicated refrigerant circuit configuration including a plurality of second gas coolers corresponding to the operation mode with the same suction and discharge of the expander at the time of reverse flow by switching of the operation mode It is possible to avoid, it is possible to obtain a refrigerating and air-conditioning apparatus of simple and low cost.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram showing a refrigeration air-conditioning apparatus according to Embodiment 1 of the present invention, where (a) shows a heating operation and (b) shows a cooling operation. The refrigerating and air-conditioning apparatus according to the present invention has a refrigerant circuit whose basic configuration is a two-axis series (high stage) configuration, and uses carbon dioxide as a refrigerant. The refrigerant circuit having the two-axis series (high stage) configuration will be described later. In FIG. 1A, the gas cooler 3 corresponds to an indoor unit side heat exchanger, and the evaporator 5 corresponds to an outdoor unit side heat exchanger.

  In FIG. 1, 1 is a compressor driven by a motor 12, 2 is an oil separator, 20 is a four-way valve for switching between cooling and heating flow paths, 3 is a gas cooler, 4 is an expander, 5 is an evaporator, and 6 is The accumulator, 14 is a second compressor connected to the main shaft 11 of the expander 4 and driven, 19 is a backflow preventing means provided on the downstream side of the expander 4, and 15 is parallel to the expander 4 and the backflow preventing means 19. A second pressure reducing device 18 provided in the bypass pipe connected to the flow pipe 18 is a flow rate control means 18 for bypassing the second compressor 15.

Here, the basic refrigerant circuit configuration of the refrigerating and air-conditioning apparatus according to the present invention will be described.
FIG. 2 shows a basic refrigerant circuit having a two-axis series (high stage) configuration, and it is assumed that carbon dioxide is used as the refrigerant. In the figure, the compressor 1 driven by the motor 12 is not coaxial with the expander 4, and the main shaft of the expander 4 drives the second compressor 14. And the 2nd compressor 14 is pipe-connected in series in the compressor 1 and a refrigerant circuit, and is arrange | positioned so that a two-stage compression of a refrigerant | coolant may be performed. The refrigerant compressed by the compressor 1 and the second compressor 14 removes the oil separated from the oil separator 2 connected to the discharge side of the second compressor 14 from the suction side of the compressor 1 and the outflow of the accumulator 6. After returning to a later position, the gas cooler 3 is used for cooling. The high-pressure refrigerant gas after being cooled by the gas cooler 3 recovers expansion power when the pressure is reduced by the expander 4, and this recovered power is transmitted to the second compressor 14 through the main shaft 11. The refrigerant after being decompressed by the expander 4 is configured by a refrigerant circuit that is heated by the evaporator 5, passes through the accumulator 6 that stores excess liquid refrigerant, and then returns to the suction side of the compressor 1. .

  In the refrigerating and air-conditioning apparatus configured as described above, the expander 4 is of a type that has no valve opening / closing control mechanism and has a simple structure with a stroke volume and an internal volume ratio determined. In such an expander, since the rotational speed of the main shaft 11 is determined by the volume flow rate, it is necessary to match the rotational speed with the second compressor 14.

  Here, for explanation, a comparison with the expander coaxial configuration shown in FIG. 3 is performed. FIG. 3 is a basic refrigerant circuit diagram of an expander coaxial configuration in which the basic configuration is simplified based on FIG. 19 of the conventional example. In FIG. 3, the expander 4 and the compressor 1 driven by the motor 12 are coaxial with the main shaft 11. In this case, the flow rates in the expander 4 and the compressor 1 must match so that the expander 4 and the compressor 1 have the same rotation speed.

Here, the specific volume of the refrigerant on the suction side of the compressor 1 is υs, the specific volume of the inlet of the expander 4 is νexi, the stroke volume of the compressor 1 is Vst, the confined volume of the expander 4 in the pre-expansion state, so-called stroke volume. Is Vex, the flow rates on the compressor side and expander side match,
Vex / υexi = Vst / υs (1)
Must hold. The above υexi and υs are determined from the operating conditions. In order to satisfy the expression (1) for various operating conditions, it is necessary to adjust the volume flow rate of the refrigerant at the expander inlet unless Vex and Vst are variable.
For example, in the case of νexi / υs> Vex / Vst, the expander side tends to rotate faster than the compressor side, so it is necessary to bypass and reduce the flow rate passing through the expander. On the contrary, if υexi / υs <Vex / Vst, the expander side becomes slow. Therefore, the refrigerant discharged from the gas cooler is decompressed and expanded to a predetermined pressure to increase the volume flow rate at the expander inlet. And the rotation speed of the expander can be balanced.

  Therefore, FIG. 4 is a refrigerant circuit diagram having a configuration in which the second decompression means 15 and the pre-expansion valve 16 which are bypass expansion valves are added to match the flow rate of the compressor and the expander based on the refrigerant circuit of FIG. Show. In FIG. 4, 15 is a second decompression means provided in the middle of the pipe connection from the outlet side of the gas cooler 3 to the inlet side of the evaporator 5 so as to bypass the expander 4, and 16 is on the inflow side of the expander 4. The other components are the same as those in FIG. Since the decompression amount in the pre-expansion valve 16 and the flow amount flowing through the second decompression means 15 of the bypass pipe do not contribute to the recovery of the expansion power, the stroke volume Vex of the expander is determined with respect to the stroke volume Vst of the compressor 1. Therefore, it is preferable to select the Vex so that the bypass and the pre-expansion do not have to be performed under the operating condition where the efficiency is most desired to be improved, that is, the expression (1) is satisfied.

Here, the ratio of the bypassed flow rate to the total flow rate is defined as a bypass ratio x, and the ratio of the differential pressure before and after the pre-expansion valve to the total high / low pressure difference that reduces the pressure between the gas cooler / evaporator is defined as the preexpansion rate y. For the refrigerating and air-conditioning apparatus provided with the refrigerant circuit having the expander coaxial configuration in FIG. 4 described above, the heating intermediate condition having the largest contribution to SEER (annual average energy consumption efficiency) among the four representative operating conditions for air conditioning applications. Thus, when the stroke volume Vex of the expander is set with respect to the stroke volume Vst of the compressor 1 so that x = y = 0%, x and y in each condition are numerical values shown in FIG.
Thereafter, when comparing the efficiency of COP and SEER, the values at x and y in the refrigerant circuit of the expander coaxial configuration are used as a reference.

In the case of a refrigerant circuit having a two-shaft series (high stage) configuration as shown in FIG. 2, the flow rate matching between the expander 4 and the second compressor 14 must be matched, but the second compressor When the stroke volume of 14 is V2, it is necessary to match both the stroke volume Vex of the expander and the V2 with respect to the stroke volume Vst of the compressor 1.
Here, if the specific volume of the refrigerant on the suction side of the second compressor 14 is υm, the rotational speed of the compressor is N1, and the rotational speed of the expander / second compressor is N2,
N2 / Vex / vexi = N2 / V2 / vm = N1-Vst / vs (2)
Need to hold.
Also, it must be taken into account that υm is recovered from the expander 4 and determined from the power used by the second compressor 14 and V2. That is, as in the case of the refrigerant circuit having the expander coaxial configuration in FIG. 4, when the flow rate matching is attempted by bypass or pre-expansion, the bypass ratio x or the pre-expansion rate y is not limited to Vst and Vex, It is determined for the combination of N2.

As in the case of the expander coaxial configuration, when Vex and V2 with respect to Vst are set so that the bypass ratio x = pre-expansion rate y = 0% in the heating intermediate condition having the largest contribution to SEER, x and y are numerical values shown in the middle of FIG.
The COP and SEER in the biaxial series (high stage) refrigerant circuit with respect to the expander coaxial configuration refrigerant circuit in each condition are slightly biaxial series (high stage) configuration as shown in the lower part of FIG. Is better. As for the expansion volume ratio of the expander, both the case of the expander coaxial and the case of two-shaft series are used as a standard value that does not cause excess and shortage in the heating intermediate condition and causes no expansion loss. The same unless otherwise noted.

  Further, since there is no need for pre-expansion only by bypass, a refrigerant circuit having a configuration in which the second pressure reducing means 15 is provided in the middle of the pipe bypassing the expander as shown in FIG. 8 is sufficient. The rotational speeds of the expander / second compressor and the compressor under each condition at this time are the rotational speeds shown in FIG.

FIG. 9 is a refrigerant circuit diagram of a two-axis parallel configuration, in which the second compressor is arranged in parallel with the compressor 1 in the refrigerant flow path, and the auxiliary motor 17 is provided on the main shaft 11 of the expander / second compressor. The basic refrigerant circuit in the case is shown. Regarding flow rate matching in the refrigerant circuit of such a biaxial parallel configuration,
N2 / Vex / vexi = N2 / V2 / vs + Nl / Vst / vs (3)
This relationship is required.
Since the flow rate on the second compressor 14 side is determined with respect to N2 determined on the expander 4 side with respect to the total flow rate, the flow rate is balanced if the compressor 1 is driven with N1 corresponding to the remaining flow rate. At this time, it is not always possible to cover the compression work for the flow rate of the second compressor with the recovered power of the expander. However, since the auxiliary motor 17 can absorb the excess or deficiency of the power, matching is performed without performing bypass or pre-expansion. It becomes possible.

  The ratio of the COP and SEER to the expander coaxial configuration in the case of this two-axis parallel (motor combined use) configuration, and the respective rotation speeds of the expander / second compressor and the compressor are the numerical values shown in FIG. By bypassing in the series configuration, the COP is better than the two-shaft series configuration because the entire flow rate is recovered without bypassing even if the rotational speed N2 of the expander / second compressor is kept low. Recognize.

  In FIG. 1 showing Embodiment 1 of the present invention, when the cooling operation is switched by the four-way valve 20, the indoor unit becomes the gas cooler 3 and the outdoor unit becomes the evaporator 5 as shown in FIG. At this time, the direction of the refrigerant flow before and after the expander 4 is reversed, but since the backflow prevention means 19 is provided in the outlet side pipe of the expander 4, the total flow rate is the second without flowing back in the expander 4. The pressure reducing means 15 is routed. Along with this, the flow rate control means 18 is opened, and the refrigerant discharged from the compressor 1 bypasses the second compressor.

  By using a plurality of four-way valves, both the heating operation and the cooling operation can be configured to flow through the expander in the same direction. Simplification and cost reduction can be obtained. On the other hand, in the case of a coaxial refrigerant circuit, the expander cannot be stopped even during reverse flow, so a complicated refrigerant circuit configuration is used so that the flow direction in the expander is the same during cooling operation and heating operation. I have to take it.

  As described above, by arranging the backflow prevention means 19 in the outlet side piping of the expander 4 and the flow rate control means 18 in the bypass flow path in parallel with the second compressor 14, the expansion is performed at the time of backflow by switching between the cooling operation and the heating operation. In the case of a configuration in which power recovery is not performed, the ratio of COP (coefficient of performance) and SEER (annual average energy consumption efficiency) in each condition to that in the refrigerant circuit (FIG. 3) of the expander coaxial configuration is shown in FIG. It becomes a numerical value, and the COP reduction is 5 to 10% under the condition of cooling without power recovery, but the SEER reduction is suppressed to 2% or less because the contribution is low.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIG.
FIGS. 12A and 12B are refrigerant circuit diagrams showing the second embodiment, where FIG. 12A shows a heating operation and FIG. 12B shows a cooling operation. The basic configuration of the second embodiment is a refrigerant circuit having a two-axis parallel (motor combined) configuration described in FIG. In FIG. 12, 4 a and 4 b are expansion devices for heating operation and cooling operation, 19 a and 19 b are backflow prevention means, and 17 is an auxiliary motor provided on the main shaft 11. In addition, the same code | symbol is attached | subjected to FIG. 1 and an equivalent part, and description is abbreviate | omitted.
In FIG. 12, the second compressor 14 is arranged in parallel with the compressor 1 in the refrigerant flow path, and includes two expanders 4a and 4b arranged in parallel on the pipe between the gas cooler 3 and the evaporator 5, Refrigerant circuit configurations are provided on the outlet side of the expander corresponding to the reverse flow of the refrigerant by switching between the cooling operation and the heating operation, respectively. In this figure, the backflow prevention means 19a and 19b are provided on the outlet side (outflow side) of the expander. However, the present invention is not limited to this and may be installed on the opposite inlet side (inflow side). . 12A corresponds to the indoor unit, and the evaporator 5 corresponds to the outdoor unit. When the four-way valve 20 is switched to the cooling state in FIG. 12B, the indoor unit is the evaporator 5 and the outdoor unit. The machine becomes the gas cooler 3.

  Regarding the reverse flow of the refrigerant in the expander portion by switching between the cooling and heating operations, as shown in FIG. 12, an expander 4a for heating operation and an expander 4b for cooling operation are arranged on the same main shaft 11, respectively. By providing a backflow prevention means 19a, 19b on the outlet side pipe of the 2WAY expansion mechanism section in which the refrigerant flows through the expander 4a side during the heating operation and the refrigerant flows through the expander 4b side during the cooling operation, The expansion power can be recovered during both the cooling operation and the heating operation, and a flow rate control means for bypassing the second compressor 14 is not necessary.

  In the two-axis parallel (motor combined) basic refrigerant circuit shown in FIG. 9, the balance between the flow rate and power of the second compressor co-operated with the expander can be absorbed by the auxiliary motor 17, but the expansion volume ratio is fixed. Underexpansion and overexpansion loss cannot be eliminated for arbitrary conditions. However, in the second embodiment, the expansion volume ratio is set such that the expansion loss is zero for each condition of the cooling operation and the heating operation by providing two expanders in parallel and using the 2WAY expansion mechanism. Is possible.

  In this embodiment, the ratio of the expansion volume of the expander 4a to the heating intermediate condition and the ratio of the COP and SEER to the refrigerant circuit of the expander coaxial configuration when the expander 4b is adjusted to the cooling intermediate condition are shown in FIG. It is better than the value obtained by the expansion volume ratio at which no expansion loss occurs under the heating intermediate condition in the case of FIG. 9 by the amount of the expansion volume ratio on the cooling operation side, and is further efficient. A refrigeration air conditioner is obtained.

Embodiment 3 FIG.
A third embodiment of the present invention will be described with reference to FIG. FIG. 14A shows a heating operation, and FIG. 14B shows a cooling operation. The third embodiment is basically based on a refrigerant circuit having a biaxial series (high stage) configuration described with reference to FIG. In FIG. 14, 21 is a second gas cooler, and 18 is a flow rate control means for piping bypassing the second gas cooler. 1 and 12 are assigned the same reference numerals, and descriptions thereof are omitted.
In the heating operation in FIG. 14A, the gas cooler 3 corresponds to the indoor unit and the evaporator 5 corresponds to the outdoor unit. By switching the four-way valve 20, the evaporator 5 becomes the indoor unit and the gas cooler in the cooling operation of FIG. 3 is an outdoor unit.

  An embodiment is described in which backflow prevention means 19a and 19b are provided in the outlet side pipes of the expander 4a for heating operation and the expander 4b for cooling operation, respectively, and the expansion power is recovered in both the cooling operation and the heating operation. Same as 2. In the third embodiment, the second gas cooler 21 is further provided in the pipe between the compressor 1 and the second compressor 14, and after the refrigerant is compressed by the compressor 1, the discharged high-pressure gas refrigerant is used as the second compressor. Before being compressed at 14, the second gas cooler 21 is used for cooling.

  Here, the refrigerant | coolant state in this Embodiment 3 is demonstrated using FIG. FIG. 15 is a ph diagram illustrating an intermediate cooling two-stage compression cycle, in which the horizontal axis represents enthalpy h and the vertical axis represents pressure p. In the figure, point a is the suction part of the compressor 1, point b is the discharge part of the compressor 1, point c is the outlet part of the second gas cooler 21, point d is the discharge part of the second compressor 14, and point e is the gas cooler. The outlet part 3 and the point f indicate the respective refrigerant states at the outlet part of the expander 4 (during cooling operation). As shown in the figure, compared with the case where the compression stroke is performed without the intermediate cooling without using the second gas cooler 21 (a → b → b ′ operation in the figure), the intermediate cooling two-stage compression (a in the figure) (Bb−ha)> (hb−ha) + (hd−hc) is expressed by the enthalpy value in the case of → cooling to the point c after the b compression stroke and performing the c → d compression stroke at a high stage. ), The work required for compression is reduced, and the COP for the same refrigeration capacity (ha-hf) is improved. Since the heating capacity is changed from (hb'-he) to (hb-hc) + (hd-he) during heating, the COP is not improved as during cooling.

  Further, since the second gas cooler 21 cannot be moved between the outdoor unit and the indoor unit in accordance with the cooling operation and the heating operation, the second gas cooler 21 is provided in the outdoor unit, and the cooling operation having a greater efficiency improvement effect. It only works at times. During the heating operation, the flow rate control means 18 is opened and detoured.

  The ratio of the COP and SEER expansion circuit coaxial configuration in the refrigerant circuit having the two-shaft series (high stage) 2WAY expander and having the intermediate cooling during the cooling operation is the value shown in FIG. This is because the expansion volume ratio is reduced in accordance with the two conditions of cooling and heating operation, the bypass amount from the second decompression means 15 is suppressed, and the expansion volume ratio is also reduced in accordance with the two conditions of cooling and heating operation. Due to the effect and the effect of intermediate cooling, the SEER value is as good as the two-axis parallel (motor combined) 2WAY expander of the second embodiment.

Embodiment 4 FIG.
A fourth embodiment of the present invention will be described with reference to FIG.
FIG. 17 is a refrigerant circuit diagram based on the two-axis series (high stage) configuration shown in FIG. 1, wherein (a) shows a heating operation and (b) shows a cooling operation. In the figure, 22 is an ejector, and 23 is a second four-way valve. The same or corresponding parts as those in FIG.

In the present embodiment, the second decompression means 15 is combined with the ejector 22 and the accumulator 6 so as to recover energy by the ejector effect with respect to the decompressed flow rate where the expansion power is not recovered by bypass or reverse flow.
The expansion power recovery is performed by the expander 4 during the heating operation of FIG. 17A, but the amount bypassed for flow rate matching is used for recovery by the ejector 22 under conditions other than the heating intermediate. On the other hand, during the cooling operation of (b), the backflow prevention means 19 does not flow into the expander 4, and the entire flow rate is reduced via the ejector 22.

  In general, the energy efficiency of the ejector is about 20% lower than the power recovery efficiency by the expander. However, even if the ejector efficiency is 20%, the ratio of COP and SEER to the expander coaxial configuration is shown in FIG. The COP is improved by the amount of the ejector effect with respect to the total flow rate during cooling and the bypass flow rate during heating rating as compared to the refrigerant circuit having the two-axis series high stage (1WAY) configuration of FIG.

  In any of the above-described embodiments, the oil separated from the oil separator 2 to the outlet side piping of the accumulator 6 is returned to the inlet of the gas cooler 3 from the accumulator 6 through the compressor 1 in both cases of cooling and heating. The nearby piping portion is kept rich in oil, and the efficiency of the compression mechanism portion can be improved by the oil seal effect without lowering the heat exchange efficiency of the gas cooler and the evaporator.

  In addition, since the refrigeration air conditioners according to Embodiments 1 to 4 of the present invention use carbon dioxide having a global warming potential of 1 as the refrigerant to be used, there is an adverse effect on the global environment such as ozone layer destruction and global warming. A small refrigeration air conditioner can be provided.

2 is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention. FIG. FIG. 3 is a basic refrigerant circuit diagram of a biaxial series (high stage) configuration according to Embodiment 1 of the present invention. FIG. 4 is a refrigerant circuit diagram for explaining an expander coaxial configuration according to the first embodiment of the present invention. It is a refrigerant circuit diagram which concerns on Embodiment 1 of this invention and shows an expander coaxial structure. It is a table | surface which concerns on Embodiment 1 of this invention and shows the reference value in an expander coaxial structure. It is a table | surface which concerns on Embodiment 1 of this invention, and shows the characteristic value in the refrigerant circuit figure of a biaxial serial (high stage) structure. It is a table | surface showing the rotation speed in the refrigerant circuit figure of 2 axis | shaft serial (high stage) structure in connection with Embodiment 1 of this invention. FIG. 3 is a basic refrigerant circuit diagram for explaining an expander coaxial configuration according to the first embodiment of the present invention. It is a refrigerant circuit diagram which concerns on Embodiment 1 of this invention and shows an expander coaxial structure. It is a table | surface which concerns on Embodiment 1 of this invention, and shows the characteristic value in the refrigerant circuit of a 2 axis | shaft parallel (motor combined use) structure. It is a table | surface which concerns on Embodiment 1 of this invention, and shows the characteristic value in the refrigerant circuit of a biaxial serial high stage (1WAY) structure. It is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to Embodiment 2 of the present invention. It is a figure which concerns on Embodiment 2 of this invention, and shows a COP ratio with respect to an expander coaxial structure. It is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to Embodiment 3 of the present invention. It is a ph diagram for explaining the intermediate cooling two-stage compression cycle according to the third embodiment of the present invention. It is a figure which concerns on Embodiment 3 of this invention, and shows a COP ratio with respect to an expander coaxial structure. It is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus according to Embodiment 4 of the present invention. It is a figure which concerns on Embodiment 4 of this invention, and shows a COP ratio with respect to an expander coaxial structure. It is a refrigerant circuit diagram of the conventional refrigeration air conditioner. It is a refrigerant circuit diagram of another conventional refrigeration air conditioner.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Oil separator, 3 Gas cooler, 4, 4a, 4b Expander, 5 Evaporator, 6 Accumulator, 7 Temperature sensor, 8 Pressure sensor, 9 Calculation means, 10 Expansion ratio control means, 11 Main shaft, 12 Motor | power_engine (Motor), 13 generator, 14 second compressor, 15 second decompression means, 16 pre-expansion valve, 17 auxiliary motor, 18 flow rate control means, 19, 19a, 19b backflow prevention means, 20 four-way valve, 21 second Gas cooler, 22 ejector, 23 second four-way valve.

Claims (6)

A plurality of compressors; a gas cooler that cools the high-pressure refrigerant compressed by the compressor; an expander that extracts power by depressurizing the gas cooled by the gas cooler; and the refrigerant depressurized by the expander And at least one of the compressors is a second compressor driven by being connected to a main shaft of the expander, and the expander and the second compressor have an annual average energy The stroke volume is determined so that it is not necessary to bypass the expander or perform pre-expansion at the expander inlet under operating conditions that greatly contribute to consumption efficiency, and the second compressor is compressed with the other compressor. A refrigeration air conditioner connected to the discharge side of the machine and having a plurality of operation modes. The gas cooler is an outdoor unit side and the evaporator is an indoor unit side when the operation mode is a cooling operation, and a four-way valve that switches a flow path that is reversed when the operation is heating is provided. The refrigeration air conditioner according to 1. The refrigerating and air-conditioning apparatus according to claim 1, further comprising a second pressure reducing unit disposed in parallel with the expander. The refrigerating and air-conditioning apparatus according to claim 1, further comprising an auxiliary motor for compensating for a shortage of the recovery power of the expander with respect to the load of the second compressor. A plurality of compressors; a gas cooler that cools the high-pressure refrigerant compressed by the compressor; an expander that extracts power by depressurizing the gas cooled by the gas cooler; and the refrigerant depressurized by the expander A second compressor connected in series with the other compressor, driven by the expansion power recovered by the expander, and the second compression And a second gas cooler connected between the compressor and the other compressor to cool the refrigerant, and a flow path that bypasses the second gas cooler during heating operation of the plurality of operation modes. Air conditioner. The refrigeration air conditioner according to any one of claims 1 to 5, wherein carbon dioxide is used as a refrigerant.

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