JP2006090644A - Refrigerating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating apparatus capable of attaining high COP while balancing the mass flow of a refrigerant passing through a compressor and the mass flow of a refrigerant passing through an expander. <P>SOLUTION: A gas-liquid separator 40 is provided with an internal heat exchanging part comprising a heat exchanger tube 50 through which the refrigerant sucked into the expander 12 flows. In air-conditioning operation, the refrigerant flowing through the heat exchanger tube 50, and a liquid refrigerant stored in a liquid storage part 41 of the gas-liquid separator 40 exchange heat. As a result, the density de of the refrigerant sucked into the expander 12 is increased to balance the refrigerant mass flow Mc of the compressor 11 and the refrigerant mass flow Me of the expander 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigeration apparatus including a refrigerant circuit that compresses refrigerant and performs a vapor compression refrigeration cycle, and more particularly, to a refrigeration apparatus in which an expander constituting an expansion mechanism of the refrigerant circuit is mechanically connected to the compressor. Is.

  2. Description of the Related Art Conventionally, refrigeration apparatuses that perform a refrigeration cycle by circulating refrigerant in a refrigerant circuit are widely used in air conditioners and the like.

  For example, in the refrigeration apparatus of Patent Document 1, an expansion mechanism and a compression mechanism are connected to a refrigerant circuit. The expansion mechanism is composed of an expander composed of a scroll type fluid machine. On the other hand, the compression mechanism is composed of a compressor composed of a rotary type fluid machine. These expander and compressor are mechanically connected by a rotating shaft. Then, when the refrigerant expands in the expander, the expansion power of the refrigerant is converted into the rotation power of the compressor via the rotation shaft. In other words, this refrigeration apparatus uses the power (expansion power) obtained by the expander as drive power for the compressor, thereby realizing a highly energy-efficient refrigeration cycle, that is, a refrigeration cycle at a high COP. I have to.

  However, in the refrigeration apparatus of Patent Document 1, the power recovery efficiency of the compressor decreases because the refrigerant circuit is a closed circuit and the rotation speeds of the expander and the compressor are the same. It is difficult to achieve a high COP refrigeration cycle. This will be described below.

  In the refrigerant circuit serving as a closed circuit, the mass flow rate Me of refrigerant passing through the expander is equal to the mass flow rate Mc of refrigerant passing through the compressor. Here, Me = Ve × de (Ve: volume circulation amount of refrigerant passing through the expander, de: refrigerant suction density of the expander), Mc = Vc × dc (Vc: volume circulation amount of the refrigerant passing through the compressor) , Dc: refrigerant intake density of the compressor). The volume circulation amount (Vc, Ve) is determined by the cylinder volume of each fluid machine × the rotation speed of each fluid machine.

  Here, since the mass flow rate Me of the expander is equal to the mass flow rate Mc of the compressor, the relationship Ve / Vc = de / dc is established from the above equation. Note that Ve / Vc is a fixed value determined by the cylinder volume of each fluid machine since the rotation speeds of the expander and the compressor are the same. Therefore, in this refrigeration system, the refrigerant mass flow rates Me and Mc of the expander and the compressor can be balanced by designing the cylinder volume of each fluid machine based on the density ratio (de / dc).

  However, when this type of refrigeration apparatus is used in an air conditioner or the like, it may be difficult to keep the density ratio (de / dc) constant depending on the use conditions. Specifically, for example, in an air conditioner that switches between a cooling operation and a heating operation, the cooling operation has a higher evaporation pressure of the refrigerant in the use side heat exchanger (evaporator) than the heating operation. The refrigerant suction density dc increases. As a result, the mass flow rate Me of the refrigerant passing through the expander becomes smaller than the mass flow rate Mc of the refrigerant passing through the compressor, and the refrigerant mass flow rates of the expander and the compressor cannot be balanced. Therefore, this refrigeration apparatus has a problem that it is difficult to perform a desired refrigeration cycle.

For this problem, as disclosed in Patent Document 2, a countermeasure has been proposed in which a bypass pipe for bypassing the expander is provided in the refrigerant circuit. That is, when the mass flow rate Me of the refrigerant passing through the expander is smaller than the mass flow rate Mc of the refrigerant passing through the compressor, a part of the refrigerant after heat dissipation is introduced into the bypass pipe, Bypassing is performed so that the mass flow rate of the refrigerant circuit as a whole is balanced.
Japanese Patent Laid-Open No. 2001-107881 JP-A-2001-116371

  However, in the refrigeration apparatus of Patent Document 2, since a part of the refrigerant bypasses the expander, in the expander, the expansion power is reduced by the amount of internal energy of the bypassed refrigerant. Therefore, the recovery power of the compressor is also reduced, resulting in a problem that the COP of the refrigeration apparatus is lowered.

  The present invention was devised in view of such problems, and its purpose is to balance the mass flow rate of the refrigerant passing through the compressor and the mass flow rate of the refrigerant passing through the expander, It is to provide a refrigeration apparatus that can achieve a high COP.

  The present invention uses a gas-liquid separator having an internal heat exchanger for exchanging heat between the refrigerant expanded in the expander and the refrigerant sucked into the expander.

  Specifically, the first invention is a refrigerant circuit that performs a refrigeration cycle by connecting a compressor (11), a heat source side heat exchanger (21), an expander (12), and a use side heat exchanger (22). (10) is provided, and the compressor (11) and the expander (12) are mechanically connected to each other, and a refrigeration apparatus that recovers expansion power of the expander (12) is assumed. The refrigeration apparatus includes a gas-liquid separator (40) that separates the refrigerant expanded by the expander (12) into a liquid refrigerant and a gas refrigerant and temporarily stores the refrigerant, and the gas-liquid separator (40 ) Includes an internal heat exchange section (50) for exchanging heat between the liquid refrigerant separated by the gas-liquid separator (40) and the refrigerant sucked into the expander (12).

  In the said 1st invention, a gas-liquid separator (40) is provided in a refrigerant circuit (10). The gas-liquid separator (40) separates the gas-liquid two-phase refrigerant after being expanded by the expander (12) into a gas refrigerant and a liquid refrigerant. In addition, the gas-liquid separator (40) is provided with an internal heat exchange section (50). The internal heat exchange unit (50) exchanges heat between the refrigerant sucked into the expander (12) and the liquid refrigerant stored in the gas-liquid separator (40).

  Here, since the refrigerant sucked into the expander (12) has a higher temperature than the liquid refrigerant after being expanded in the expander (12), the internal heat exchange unit (50) The refrigerant sucked is cooled. For this reason, the suction refrigerant density de of the expander (12) can be increased. Therefore, for example, during the cooling operation, even when the mass flow rate Mc of the refrigerant passing through the compressor (11) increases, by cooling the refrigerant sucked into the expander (12) following this, The refrigerant mass flow rate Me passing through the expander (12) can be increased to balance the refrigerant mass flow rates Mc and Me.

  According to a second aspect of the present invention, the refrigeration apparatus of the first aspect includes a heat exchange amount adjustment mechanism (60) that changes the heat exchange amount of the refrigerant in the internal heat exchange section (50) according to operating conditions. is there. Here, the “heat exchange amount adjustment mechanism” means that the heat exchange amount can be finely adjusted according to the operating conditions, and two-step adjustment of whether the heat exchange amount is substantially zero or a predetermined value. This means that (ON / OFF control) can be performed.

  In the second aspect of the invention, the heat exchange amount between the refrigerant sucked into the expander (12) and the liquid refrigerant separated by the gas-liquid separator (40) is a heat exchange amount adjusting mechanism ( 60) modified by. For this reason, when the refrigerant mass flow rate Me of the expander (12) becomes larger than the refrigerant mass flow rate Mc of the compressor (11) due to the change of the operating condition, the heat exchange amount in the internal heat exchange unit (50) is adjusted. Thus, the refrigerant mass flow rate Me of the expander (12) and the refrigerant mass flow rate Mc of the compressor (11) can be made equal.

  According to a third invention, in the refrigeration apparatus of the first or second invention, the gas-liquid separator (40) includes a liquid storage part (41) for storing the separated liquid refrigerant, and the liquid storage part (41). And a heat transfer pipe (50) through which the refrigerant sucked into the expander (12) flows, and the heat transfer pipe (50) includes the liquid refrigerant in the liquid storage section (41) and the heat transfer pipe ( 50) This constitutes an internal heat exchanging section for exchanging heat with the refrigerant inside.

  In the third invention, the gas-liquid separator (40) is provided with the heat transfer tube (50) as an internal heat exchange section. The heat transfer tube (50) is arranged so as to be adjacent to the liquid reservoir (41). For this reason, the refrigerant sucked into the expander (12) is cooled by the liquid refrigerant stored on the outer surface of the heat transfer tube (50) when flowing through the heat transfer tube (50). Therefore, the suction refrigerant density de of the expander (12) can be reliably increased.

  According to a fourth invention, in the refrigeration apparatus of the third invention, there is provided a refrigerant switching mechanism (31, 33) for switching between the cooling operation and the heating operation by changing the refrigerant circulation direction of the refrigerant circuit (10). The heat exchange amount adjusting mechanism (60) causes the refrigerant to exchange heat in the internal heat exchange section (50) only during the cooling operation.

  In the fourth aspect of the invention, the refrigerant switching mechanism (31, 33) is provided in the refrigerant circuit (10). The refrigerant switching mechanism (31, 33) switches the refrigerant circulation direction so that the use side heat exchanger (22) serves as an evaporator and the use side heat exchanger (21) serves as a radiator. The heating operation can be switched.

  Here, the heat exchange amount adjustment mechanism (60) causes heat exchange of the refrigerant in the internal heat exchange unit (50) only during the cooling operation. For this reason, during the cooling operation in which the refrigerant mass flow rate Me of the expander (12) tends to be smaller than the refrigerant mass flow rate Mc of the compressor (11), the suction refrigerant density de of the expander (12) is increased. The refrigerant mass flow rate Me of (12) and the refrigerant mass flow rate Mc of the compressor (11) can be made equal.

  On the other hand, during the heating operation, the cylinder volume ratio of the expander (12) and the compressor (11) is set according to the density ratio between the suction refrigerant density de of the expander (12) and the suction refrigerant density dc of the compressor (11). By designing, the refrigerant mass flow rate Me of the expander (12) and the refrigerant mass flow rate MC of the compressor (11) can be made equal. Therefore, it is not necessary to perform heat exchange of the refrigerant in the internal heat exchange section (50) by the heat exchange amount adjustment mechanism (60).

  According to a fifth aspect of the present invention, in the refrigeration apparatus of the third or fourth aspect, the heat exchange amount adjusting mechanism (60) bypasses the heat transfer pipe (50) and sucks the refrigerant into the expander (12). 46), a first motor-operated valve (36) that adjusts the flow rate of refrigerant flowing through the heat transfer pipe (50), and a second motor-operated valve (37) that adjusts the refrigerant flow rate of the bypass pipe (46). It is what.

  In the fifth aspect of the invention, the heat exchange amount of the refrigerant in the heat transfer tube (50) is adjusted by adjusting the opening degree of the first and second motor operated valves (36, 37). Specifically, for example, when the first motor-operated valve (36) is fully opened and the second motor-operated valve (37) is fully closed, the flow rate of the refrigerant flowing through the heat transfer tube (50) becomes maximum, and the refrigerant in the heat transfer tube (50). The amount of heat exchange is adjusted to the maximum. On the other hand, for example, when the first motor-operated valve (36) is fully closed and the second motor-operated valve (37) is fully opened, the flow rate of the refrigerant flowing through the heat transfer tube (50) becomes substantially zero, and the heat transfer tube (50) The heat exchange amount of the refrigerant is also zero. As described above, the heat exchange amount in the heat transfer tube (50) can be adjusted from zero to the maximum value by adjusting the opening degree of the first and second motor operated valves (36, 37) to a predetermined opening degree. . Therefore, heat exchange of the refrigerant according to the operating conditions can be performed, and the refrigerant mass flow rate Me of the expander (12) and the refrigerant mass flow rate Mc of the compressor (11) can be made equal.

  According to a sixth invention, in the refrigeration apparatus of the fourth invention, the heat exchange amount adjusting mechanism (60) is constituted by a four-way switching valve (32).

  In the sixth aspect of the invention, the refrigerant flow is changed by switching the four-way switching valve (32) as the heat exchange amount adjusting mechanism (60). Therefore, for example, during the cooling operation, the four-way switching valve (32) is switched so that the refrigerant flows through the heat transfer tube (50), while during the heating operation, the four-way switching valve is set so as not to flow the refrigerant through the heat transfer tube (50). By switching (32), the refrigerant mass flow rate Me of the expander (12) and the refrigerant mass flow rate Mc of the compressor (11) can be made equal in both operations.

  According to a seventh invention, in the refrigeration apparatus of the fourth invention, the heat exchange amount adjusting mechanism (60) includes a bypass pipe (46) for allowing the refrigerant to be sucked into the expander (12) by bypassing the heat transfer pipe (50). The first electromagnetic on-off valve (34) that allows or prohibits the refrigerant flow in the heat transfer pipe (50) and the second electromagnetic on-off valve (35) that allows or prohibits the refrigerant flow in the bypass pipe (46). It is configured.

  In the seventh aspect of the invention, the refrigerant flow in the heat transfer tube (50) is changed by opening and closing the first and second electromagnetic on-off valves (34, 35). Specifically, for example, during cooling operation, the first electromagnetic on-off valve (34) is opened, and the second electromagnetic on-off valve (35) is closed, thereby allowing the refrigerant to flow through the heat transfer tube (50). The heat transfer of the refrigerant can be performed by the heat transfer tube (50). On the other hand, for example, during the heating operation, the first electromagnetic on-off valve (34) is closed and the second electromagnetic on-off valve (35) is opened, thereby allowing the refrigerant to flow through the bypass pipe (46). It is possible to prevent the refrigerant from flowing through the heat transfer tube (50). That is, in this state, heat exchange of the refrigerant can be prevented from being performed by the heat transfer tube (50). Therefore, during both operations, the refrigerant mass flow rate Me of the expander (12) and the refrigerant mass flow rate Mc of the compressor (11) can be made equal.

  According to an eighth aspect of the present invention, in the refrigeration apparatus of the fourth aspect, the heat exchange amount adjusting mechanism (60) is configured by a combination of a pipe and a check valve (81, 82, 83, 84). .

  In the eighth aspect of the invention, the predetermined piping path and the check valves (81, 82, 83, 84) are provided as the heat exchange amount adjusting mechanism (60). For this reason, for example, a check valve (81, 82, 83, 84) and a piping path are set so that the refrigerant flows through the heat transfer pipe (50) during the cooling operation, and the refrigerant does not flow through the heat transfer pipe (50) during the heating operation. By providing this, the refrigerant mass flow rate Me of the expander (12) and the refrigerant mass flow rate Mc of the compressor (11) can be equalized during both operations.

  According to a ninth invention, in the refrigeration apparatus of the first to eighth inventions, the refrigerant circuit (10) includes a first injection for sending the gas refrigerant of the gas-liquid separator (40) to the suction side of the compressor (11). A pipe (44) and a gas control valve (38) for adjusting the refrigerant flow rate of the first injection pipe (44) are provided.

  In the ninth aspect of the invention, the gas refrigerant separated by the gas-liquid separator (40) can be sent to the suction side of the compressor (11) via the first injection pipe (44). Therefore, so-called gas injection can be performed as necessary, and the amount of gas injection can be adjusted by changing the opening of the gas control valve (38).

  A tenth aspect of the invention is the refrigeration apparatus according to any one of the first to ninth aspects of the invention, wherein the refrigerant refrigerant (40) is supplied with the liquid refrigerant of the gas-liquid separator (40) to the suction side of the compressor (11). A second injection pipe (48) to be sent and a liquid control valve (39) for adjusting the refrigerant flow rate of the second injection pipe (48) are provided.

  In the tenth aspect of the invention, the liquid refrigerant separated by the gas-liquid separator (40) can be sent to the suction side of the compressor (11) via the second injection pipe (48). Therefore, if necessary, so-called liquid injection can be performed, and the amount of liquid injection can be adjusted by changing the opening of the liquid control valve (39).

  An eleventh aspect of the invention is the refrigeration apparatus according to any one of the first to tenth aspects of the invention, wherein the refrigerant circuit (10) has a plurality of use side heat exchangers (22a, 22b, 22c) connected in parallel, A plurality of flow rate adjusting valves (61a, 61b, 61c) for adjusting the flow rates of the refrigerant flowing into the use side heat exchangers (22a, 22b, 22c) are provided.

  In the eleventh aspect of the invention, the refrigerant circuit (10) is provided with a plurality of use side heat exchangers (22a, 22b, 22c). That is, in this refrigeration apparatus, it is possible to simultaneously perform cooling (cooling) or heating (heating) with a plurality of usage-side heat exchangers (22a, 22b, 22c). In addition, by adjusting the openings of the plurality of flow rate adjustment valves (61a, 61b, 61c) corresponding to the respective use side heat exchangers (22a, 22b, 22c), the use side heat exchangers (22a, 22b, 22c) ) Can be individually adjusted.

  According to a twelfth aspect, in the refrigeration apparatus according to any one of the first to eleventh aspects, carbon dioxide is used as a refrigerant in the refrigerant circuit (10).

  In the twelfth aspect of the invention, the refrigerant circuit (10) is filled with carbon dioxide as a refrigerant. Since this carbon dioxide can increase the differential pressure of the refrigeration cycle as compared with other refrigerants, the expansion power of the refrigerant obtained by the expander (12) can be increased.

  According to the first aspect of the invention, the liquid refrigerant separated by the gas-liquid separator (40) and the refrigerant sucked into the expander (12) are heat-exchanged by the internal heat exchanging part (50). The suction refrigerant density de, that is, the mass flow rate Me of the expander (12) can be increased. Accordingly, the refrigerant mass flow rate (Me and Mc) of the compressor (11) and the expander (12) is balanced by performing heat exchange of the refrigerant with a predetermined heat exchange amount in the internal heat exchange section (50). A desired refrigeration cycle can be performed with this refrigeration apparatus.

  Here, like this patent document 2, this invention can balance refrigerant | coolant mass flow rate Me and Mc, without bypassing a part of refrigerant | coolant from an expander. That is, in the refrigeration apparatus of Patent Document 2, the expansion power of the expander decreases and the COP also decreases. However, in the present invention, all the refrigerant can be introduced into the expander (12). A decrease can be avoided.

  In the present invention, the liquid refrigerant separated by the gas-liquid separator (40) and the refrigerant sucked into the expander (12) are subjected to heat exchange. Here, in the same type of refrigerant, the liquid refrigerant has a higher heat transfer rate than the two-phase refrigerant or the gas refrigerant, so the heat exchange rate in the internal heat exchanger (50) is improved. Can be made. Therefore, the refrigerant sucked into the expander (12) can be effectively cooled, and as a result, the internal heat exchange part (50) and the gas-liquid separator (40) can be designed compactly.

  Furthermore, in the present invention, since the gas-liquid separator (40) also serves as the internal heat exchange part (50), the gas-liquid separator (40) and the internal heat exchange part (50) are provided separately. In comparison, the refrigeration apparatus can be made compact.

  Moreover, in this invention, the liquid refrigerant isolate | separated with the gas-liquid separator (40) can be conveyed to predetermined piping or a heat exchanger. For this reason, the pressure loss in piping can be reduced compared with the case where the refrigerant | coolant of a two-phase state distribute | circulates piping or a heat exchanger, for example. In addition, when the two-phase refrigerant flows through the pipe or the heat exchanger, the refrigerant passing sound is likely to be noise, but this can be prevented in the present invention.

  According to the second aspect of the invention, the heat exchange amount adjusting mechanism (60) is provided so that the heat exchange amount of the internal heat exchange section (50) can be adjusted according to the operating conditions. Therefore, in this refrigeration apparatus, the refrigerant mass flow rates (Me and Mc) of the compressor (11) and the expander (12) can be balanced following the change in operating conditions.

  According to the third aspect of the present invention, the suction of the expander (12) flowing through the heat transfer tube (50) is provided by providing the heat transfer tube (50) in the liquid storage part (41) of the gas-liquid separator (40). Heat can be reliably exchanged between the refrigerant and the liquid refrigerant separated by the gas-liquid separator (40). For this reason, the refrigerant | coolant mass flow rate (Me and Mc) of a compressor (11) and an expander (12) can be made to increase reliably, and the refrigerant | coolant mass flow rate (Me and Mc) of an expander (12) can be balanced.

  According to the fourth aspect of the invention, the refrigerant in the internal heat exchanger (50) is only in the cooling operation when the refrigerant mass flow rate Me of the expander (12) is likely to be smaller than the refrigerant mass flow rate Mc of the compressor (11). Heat exchange. Therefore, it is possible to reliably balance the refrigerant mass flow rates (Me and Mc) of the compressor (11) and the expander (12) during the cooling operation.

  On the other hand, during the heating operation, the cylinder volume ratio of the expander (12) and the compressor (11) is set according to the density ratio between the suction refrigerant density de of the expander (12) and the suction refrigerant density dc of the compressor (11). By designing, the refrigerant mass flow rates (Me and Mc) of the compressor (11) and the expander (12) can be balanced.

  According to the fifth aspect, the first and second motor operated valves (36, 37) and the bypass pipe (46) are provided as the heat exchange amount adjusting mechanism (60). And the heat exchange amount of the refrigerant | coolant in a heat exchanger tube (50) can be adjusted now by adjusting the opening degree of a 1st, 2nd motor operated valve (36,37) to a predetermined opening degree. Therefore, the refrigerant mass flow rates (Me and Mc) of the compressor (11) and the expander (12) can be balanced with high accuracy according to the operating conditions.

  Also, by setting the first motor-operated valve (36) to the fully open state and the second motor-operated valve (37) to the fully-closed state, the refrigerant flows through the heat transfer pipe (50) only during the cooling operation, and heat exchange of the refrigerant is performed. It can be carried out. Therefore, the effect of the third invention can be obtained.

  According to the sixth aspect of the invention, the four-way switching valve (32) is provided as the heat exchange amount adjusting mechanism (60). Then, by switching the four-way switching valve (32), the refrigerant flow can be changed between a state in which the refrigerant flows through the heat transfer pipe (50) and a state in which the refrigerant does not flow. For this reason, the refrigerant can flow through the heat transfer tube (50) only during the cooling operation by switching the four-way switching valve (32), and heat exchange of the refrigerant can be performed. Therefore, the operational effects of the third invention can be easily obtained.

  According to the seventh aspect of the invention, the first and second electromagnetic on-off valves (34, 35) and the bypass pipe (46) are provided as the heat exchange amount adjusting mechanism (60). Then, by opening the first electromagnetic on-off valve (34) and at the same time closing the second electromagnetic on-off valve (35), the refrigerant flows through the heat transfer tube (50) only during the cooling operation. Heat exchange can be performed. Therefore, the effect of the third invention can be obtained.

  According to the eighth aspect of the invention, the predetermined piping path and the check valves (81, 82, 83, 84) are provided as the heat exchange amount adjusting mechanism (60). For this reason, the combination of these piping paths and check valves (81, 82, 83, 84) allows the refrigerant to flow through the heat transfer pipe (50) only during cooling operation, while the refrigerant flows into the heat transfer pipe (50) during heating operation. Can be avoided. Therefore, the third aspect of the invention can be realized only by switching control of the refrigerant circulation direction by the refrigerant switching means (31).

  According to the ninth aspect, the gas refrigerant separated by the gas-liquid separator (40) can be sent to the suction side of the compressor (11) for gas injection. Therefore, the degree of superheat of the refrigerant sucked in the compressor (11) can be adjusted, and optimal refrigeration cycle control can be performed in this refrigeration apparatus.

  According to the tenth aspect of the invention, the liquid refrigerant separated by the gas-liquid separator (40) can be sent to the suction side of the compressor (11) to perform liquid injection. Therefore, the same effect as in the ninth invention can be obtained. Further, by combining the gas injection of the ninth invention and the liquid injection of the present invention, finer refrigeration cycle control can be performed.

  Further, according to the present invention, the refrigeration oil contained in the refrigerant flowing out from the expander (12) can be returned to the suction side of the compressor (11) together with the liquid refrigerant separated by the gas-liquid separator (40). it can.

  According to the eleventh aspect of the invention, by providing a plurality of use side heat exchangers (22a, 22b, 22c), this refrigeration apparatus can be used for a so-called multi-type air conditioner or the like. In addition, the flow rate of the refrigerant flowing into each use side heat exchanger (22a, 22b, 22c) can be adjusted by each flow control valve (61a, 61b, 61c), so each use side heat exchanger (22a, 22b, 22c) The cooling (cooling) capacity of each can be adjusted individually.

  Here, since the liquid refrigerant separated by the gas-liquid separator (40) can be sent to each use-side heat exchanger (22a, 22b, 22c), for example, the above flow rate adjustment compared to the refrigerant in the two-phase state The flow rate can be easily adjusted in the valves (61a, 61b, 61c). At the same time, it is possible to reduce noise due to refrigerant pressure loss and refrigerant passage noise in relatively long pipes.

  According to the twelfth aspect, by using carbon dioxide as the refrigerant in the refrigerant circuit (10), the differential pressure in the refrigeration cycle can be increased compared to other refrigerants. Therefore, the recovery power of the expander (12) can be improved, and the COP of the refrigeration apparatus can be further improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the Invention
The refrigeration apparatus of Embodiment 1 is applied to an air conditioner (1). The air conditioner (1) is configured to perform switching between indoor cooling operation and heating operation.

As shown in FIG. 1, the air conditioner (1) includes a refrigerant circuit (10). In the refrigerant circuit (10), a refrigerant is circulated to perform a vapor compression refrigeration cycle. The refrigerant circuit (10) is filled with carbon dioxide (CO ₂ ) as a refrigerant.

  The refrigerant circuit (10) includes a compressor (11), an expander (12), an outdoor heat exchanger (21), an indoor heat exchanger (22), a gas-liquid separator (40), and a first four-way The switching valve (31) and the second four-way switching valve (32) are connected.

  The compressor (11) and the expander (12) are each constituted by a rotary piston type fluid machine having a unique cylinder volume. The compressor (11) and the expander (12) are connected to each other by the rotating shaft of the motor (13). The compressor (11) is rotationally driven by both power (expansion power) obtained by expansion of the refrigerant in the expander (12) and power obtained by energizing the motor (13). At this time, since the compressor (11) and the expander (12) are connected to the rotation shaft, their rotational speeds are always equal. Accordingly, in the refrigerant circuit (10), the ratio (Ve / Vc) between the volume circulation amount Ve of the refrigerant passing through the expander (12) and the volume circulation amount Vc of the refrigerant passing through the compressor (11) is determined by each fluid. It is a fixed value determined by the cylinder volume ratio of the machine (11, 12). This cylinder volume ratio is the ratio of the above-mentioned Ve / Vc and the density ratio de between the suction refrigerant density de of the expander (12) and the suction refrigerant density dc of the compressor (11) when the air conditioner (1) is heated. / Dc is equal, that is, the mass flow rate Me of the refrigerant passing through the expander (12) and the mass flow rate Mc of the refrigerant passing through the compressor (11) are designed to be equal. .

  The outdoor heat exchanger (21) and the indoor heat exchanger (22) are so-called cross fin type fin-and-tube heat exchangers. Outdoor air is blown to the outdoor heat exchanger (21) by a fan (not shown). In the outdoor heat exchanger (21), heat is exchanged between the outdoor air and the refrigerant. On the other hand, indoor air is blown to the indoor heat exchanger (22) by a fan (not shown). In the indoor heat exchanger (22), heat is exchanged between the indoor air and the refrigerant.

  A gas-liquid separator (40) is connected to the discharge side of the expander (12). The gas-liquid separator (40) is a sealed container that separates the two-phase refrigerant expanded by the expander (12) into liquid refrigerant and gas refrigerant. Inside the gas-liquid separator (40), a liquid storage part (41) for storing the separated liquid refrigerant is formed in the lower space, and a gas storage part (42) for storing the separated gas refrigerant is the upper space. Is formed.

  A separation liquid pipe (43) is connected to the liquid storage part (41) of the gas-liquid separator (40), while a separation gas pipe (44) is connected to the gas-liquid gas storage part (42). ing. The separation liquid pipe (43) is a pipe that sends the liquid refrigerant separated by the gas-liquid separator (40) to the second four-way switching valve (32). The separation gas pipe (44) is a so-called gas injection pipe (first injection pipe) that sends the gas refrigerant separated by the gas-liquid separator (40) to the suction side of the compressor (11). The separation gas pipe (44) is provided with a gas control valve (38) for adjusting the flow rate of the gas refrigerant sent to the suction side of the compressor (11).

  The gas-liquid separator (40) is provided with a heat transfer tube (50) penetrating the inside of the gas-liquid separator (40) so as to be adjacent to the liquid reservoir (41). One end of the heat transfer tube (50) is connected to one end of the outdoor heat exchanger (21), and the other end is connected to the second four-way switching valve (32). And the heat exchanger tube (50) comprises the internal heat exchange part which heat-exchanges the liquid refrigerant in a liquid storage part (41), and the refrigerant | coolant in this heat exchanger tube.

  The first four-way selector valve (31) and the second four-way selector valve (32) each have first to fourth ports. The first four-way selector valve (31) has a first port connected to the discharge side of the compressor (11), a second port connected to the other end of the outdoor heat exchanger (21), and a third port compressed. The fourth port is connected to one end of the indoor heat exchanger (22). On the other hand, in the second four-way selector valve (32), the first port is connected to the liquid storage part (41) of the gas-liquid separator (40) via the separation liquid pipe (43), and the second port is gas-liquid. Connected to heat transfer pipe (50) of separator (40), third port connected to suction side of expander (12), and fourth port connected to other end of indoor heat exchanger (22) .

  The first and second four-way selector valves (31, 32) are in a first state (in the solid line in FIG. 1) in which the first port and the second port are in communication with each other and the third port and the fourth port are in communication. And a second state (state indicated by a broken line in FIG. 1) in which the first port and the fourth port are communicated with each other and the second port and the third port are in communication with each other. .

  The first four-way switching valve (31) constitutes a refrigerant switching mechanism that switches the refrigerant circulation direction in order to switch between the cooling operation and the heating operation. On the other hand, the second four-way selector valve (32) constitutes a heat exchange amount adjusting mechanism (60) for changing the heat exchange amount of the refrigerant in the internal heat exchange section (50), and during the cooling operation of the air conditioner (1) Only let the refrigerant exchange heat in the heat transfer tube (50).

-Driving action-
Next, the operation | movement at the time of air_conditionaing | cooling operation and heating operation of the air conditioner (1) of Embodiment 1 is demonstrated.

(Cooling operation)
As shown in FIG. 2, during the cooling operation, the first four-way switching valve (31) is set to the first state, and the second four-way switching valve (32) is set to the second state. When the motor (13) is energized in this state, the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, the outdoor heat exchanger (21) serves as a radiator, and the indoor heat exchanger (22) serves as an evaporator. The high pressure of the refrigeration cycle is set higher than the critical pressure of carbon dioxide, which is a refrigerant.

  From the compressor (11), a supercritical high-pressure refrigerant is discharged. This high-pressure refrigerant flows into the outdoor heat exchanger (21) through the first four-way switching valve (31). In the outdoor heat exchanger (21), the high-pressure refrigerant radiates heat to the outdoor air.

  The high-pressure refrigerant radiated by the outdoor heat exchanger (21) flows through the heat transfer tube (50) of the gas-liquid separator (40). At this time, the high-pressure refrigerant is cooled by exchanging heat with the liquid refrigerant stored in the liquid storage section (41) of the gas-liquid separator (40). The high-pressure refrigerant that has flowed out of the heat transfer tube (50) flows into the expander (12) through the second four-way switching valve (32). In the expander (12), the high-pressure refrigerant expands, and the internal energy of the high-pressure refrigerant is converted into the rotational power of the compressor (11). Due to the expansion in the expander (12), the pressure of the high-pressure refrigerant decreases and changes from a supercritical state to a gas-liquid two-layer state.

  The low-pressure refrigerant decompressed by the expander (12) flows into the container of the gas-liquid separator (40). In the gas-liquid separator (40), the low-pressure refrigerant in the gas-liquid two-phase state is separated into liquid refrigerant and gas refrigerant. The low-pressure liquid refrigerant stored in the liquid storage part (41) is heated by exchanging heat with the high-pressure refrigerant flowing through the heat transfer tube (50). On the other hand, the low-pressure gas refrigerant stored in the gas storage part (42) is opened by the gas control valve (38) at a predetermined opening as appropriate, so that the compressor (11) passes through the separation gas pipe (44). It is returned to the suction side.

  The low-pressure liquid refrigerant in the liquid storage part (41) flows into the indoor heat exchanger (22) after passing through the separation liquid pipe (43) and the second four-way switching valve (32). In the indoor heat exchanger (22), the low-pressure refrigerant absorbs heat from the indoor air and evaporates. At this time, room air cooled by the low-pressure refrigerant is supplied into the room. The low-pressure refrigerant evaporated in the indoor heat exchanger (22) passes through the first four-way switching valve (31) and is sucked into the compressor (11).

(Heating operation)
As shown in FIG. 3, during the heating operation, the first four-way selector valve (31) is set to the second state, and the second four-way selector valve (32) is set to the first state. When the motor (13) is energized in this state, the refrigerant circulates in the refrigerant circuit (10) and a refrigeration cycle is performed. At that time, the indoor heat exchanger (22) serves as a radiator, and the outdoor heat exchanger (21) serves as an evaporator. The high pressure of the refrigeration cycle is set higher than the critical pressure of carbon dioxide, which is a refrigerant, as in the cooling operation.

  From the compressor (11), a supercritical high-pressure refrigerant is discharged. This high-pressure refrigerant flows into the indoor heat exchanger (22) through the first four-way switching valve (31). In the indoor heat exchanger (22), the high-pressure refrigerant radiates heat to the room air. At this time, room air heated by the high-pressure refrigerant is supplied into the room.

  The high-pressure refrigerant radiated by the indoor heat exchanger (22) flows into the expander (12) through the second four-way switching valve (32). In the expander (12), the high-pressure refrigerant expands, and the internal energy of the high-pressure refrigerant is converted into the rotational power of the compressor (11). Due to the expansion in the expander (12), the pressure of the high-pressure refrigerant decreases and changes from a supercritical state to a gas-liquid two-layer state.

  The low-pressure refrigerant decompressed by the expander (12) flows into the container of the gas-liquid separator (40). In the gas-liquid separator (40), the low-pressure refrigerant in the gas-liquid two-phase state is separated into liquid refrigerant and gas refrigerant. The low-pressure liquid refrigerant stored in the liquid storage section (41) flows through the heat transfer pipe (50) after passing through the separation liquid pipe (43) and the second four-way switching valve (32). At this time, the liquid refrigerant in the liquid storage section (41) and the liquid refrigerant in the heat transfer tube (50) are substantially isothermal, so that almost no heat is exchanged.

  The low-pressure refrigerant that has flowed out of the heat transfer tube (50) flows into the outdoor heat exchanger (21). In the outdoor heat exchanger (21), the low-pressure refrigerant absorbs heat from the outdoor air and evaporates. The low-pressure refrigerant evaporated in the indoor heat exchanger (22) passes through the first four-way switching valve (31) and is sucked into the compressor (11).

-Effect of Embodiment 1-
According to the first embodiment, the gas-liquid separator (40) is provided with the heat transfer tube (50) as an internal heat exchange unit. And by the switching of the second four-way switching valve (32), the refrigerant flowing through the heat transfer tube (50) and sucked into the expander (12), and the liquid refrigerant separated by the gas-liquid separator (40) Heat is exchanged only during cooling operation. For this reason, during the cooling operation, the refrigerant sucked into the expander (12) can be cooled, and the sucked refrigerant density de of the expander (12) can be increased. As a result, during the cooling operation of the conventional refrigeration apparatus, the refrigerant mass flow rate Mc of the compressor (11) becomes larger than the refrigerant mass flow rate Me of the expander (12) for the reason described above. Then, since the refrigerant | coolant mass flow rate Me of an expander can be enlarged, both Mc and Me can be balanced. Therefore, a desired refrigeration cycle can be performed with this refrigeration apparatus.

  Here, in this embodiment, as in Patent Document 2, the refrigerant mass flow rates Me and Mc are balanced without bypassing a part of the refrigerant from the expander. For this reason, in the refrigeration apparatus of Patent Document 2, the expansion power of the expander decreases and the COP also decreases, whereas in the present embodiment, all the refrigerant can be introduced into the expander (12). Such a decrease in COP can be avoided.

  Moreover, in the said embodiment, the liquid refrigerant isolate | separated with the gas-liquid separator (40) and the refrigerant | coolant suck | inhaled by the expander (12) are heat-exchanged. Here, in the same kind of refrigerant, the liquid refrigerant has a higher heat transfer rate than the two-phase refrigerant or the gas refrigerant, so that the heat exchange rate in the internal heat exchange section (50) is improved. be able to. Therefore, the refrigerant sucked into the expander (12) can be effectively cooled, and as a result, the internal heat exchange part (50) can be designed compactly.

  Furthermore, in the above embodiment, since the gas-liquid separator (40) also serves as the internal heat exchanger (50), the gas-liquid separator (40) and the internal heat exchanger (50) are provided separately. Compared to the above, the refrigeration apparatus can be made compact.

  Furthermore, in the above embodiment, the gas refrigerant separated by the gas-liquid separator (40) is sent to the suction side of the compressor (11) so that so-called gas injection can be performed. Therefore, the superheat degree of the refrigerant sucked in the compressor (11) can be adjusted, and the optimum refrigeration cycle can be controlled in this refrigeration apparatus.

<Modification of Embodiment 1>
Next, the refrigeration apparatus of the modification of Embodiment 1 is demonstrated. The refrigeration apparatus of this modification is provided with a plurality of indoor heat exchangers that are use side heat exchangers of the air conditioner (1). That is, the refrigeration apparatus of this modification is applied to a multi-type air conditioner. Hereinafter, differences from the first embodiment will be described.

  First to third indoor heat exchangers (22a, 22b, 22c) are connected in parallel to the refrigerant circuit (10) of this modification. Each indoor heat exchanger (22a, 22b, 22c) is provided with a fan (not shown), and indoor air is blown to each indoor heat exchanger (22a, 22b, 22c) by the corresponding fan. ing. The refrigerant circuit (10) is provided with first to third flow rate adjustment valves (61a, 61b, 61c) corresponding to the indoor heat exchangers (22a, 22b, 22c). Each flow rate adjustment valve (61a, 61b, 61c) is configured to be able to adjust the flow rate of refrigerant flowing into each indoor heat exchanger (22a, 22b, 22c). The operation of this modification is the same as that of the first embodiment except that each refrigerant branches and flows into the plurality of indoor heat exchangers (22a, 22b, 22c) and merges again.

  Also in this modification, the refrigerant sucked into the expander (12) is cooled by exchanging the heat of the refrigerant in the heat transfer tube (50) during the cooling operation, and the sucked refrigerant density de of the expander (12) is increased. Can be made. Therefore, the refrigerant mass flow rates (Mc and Me) of the compressor (11) and the expander (12) can be balanced, and a desired refrigeration cycle can be performed in the refrigerant circuit (10).

  Moreover, in this modification, by providing a plurality of indoor heat exchangers (22a, 22b, 22c), this refrigeration apparatus can be applied to a so-called multi-type air conditioner (1). Furthermore, since the flow rate of the refrigerant flowing into each indoor heat exchanger (22a, 22b, 22c) can be adjusted by each flow regulating valve (61a, 61b, 61c), the cooling of each indoor heat exchanger (22a, 22b, 22c) Capacity and heating capacity can be adjusted individually. Here, since the liquid refrigerant separated by the gas-liquid separator (40) can be sent to each indoor heat exchanger (22a, 22b, 22c), for example, compared with a refrigerant in a two-phase state or a gas state It is possible to easily adjust the flow rate in the flow rate adjustment valves (61a, 61b, 61c).

  In this multi-type, the connecting pipe between the indoor heat exchanger (22a, 22b, 22c) and the outdoor heat exchanger (21) tends to be long, so if two-phase refrigerant flows through the connecting pipe The pressure loss of the refrigerant tends to increase, and the refrigerant passing sound generated at this time tends to be noise. On the other hand, in this embodiment, since the liquid refrigerant separated by the gas-liquid separator (40) can be circulated through the connection pipe, the pressure loss and noise as described above can be effectively reduced.

<< Embodiment 2 of the Invention >>
Next, the refrigeration apparatus of Embodiment 2 will be described. The refrigeration apparatus of Embodiment 2 is different from the refrigeration apparatus of Embodiment 1 in the configuration of the refrigerant circuit (10). Hereinafter, differences from the first embodiment will be described.

  As shown in FIG. 5, the refrigerant circuit (10) includes a compressor (11), an expander (12), an outdoor heat exchanger (21), an indoor heat exchanger (22), an air heater, as in the first embodiment. A liquid separator (40), a first four-way switching valve (31), and a second four-way switching valve (33) are connected.

  Unlike Embodiment 1, in the gas-liquid separator (40) of Embodiment 2, one end of the heat transfer tube (50) is connected to the suction side of the expander (12), and the other end is connected via the liquid inflow tube (45). Connected to the second four-way selector valve (33). The liquid inflow pipe (45) is provided with a first electromagnetic on-off valve (34) that allows or prohibits the refrigerant flowing through the heat transfer pipe (50). In the liquid inflow pipe (45), one end of a bypass pipe (46) is connected between the first electromagnetic on-off valve (34) and the second four-way switching valve (33). The other end of the bypass pipe (46) is connected to the suction side of the expander (12). That is, the bypass pipe (46) causes the refrigerant to be sucked into the expander (12) by bypassing the heat transfer pipe (50). The bypass pipe (46) is provided with a second electromagnetic on-off valve (35) that allows or prohibits the refrigerant flow in the bypass pipe (46). In the configuration as described above, the bypass pipe (46) and the first and second electromagnetic on-off valves (34, 35) include a heat exchange amount adjustment mechanism (60) that changes the heat exchange amount of the refrigerant in the heat transfer pipe (50). The heat exchange of the refrigerant in the heat transfer tube (50) is performed only during the cooling operation of the air conditioner (1).

  Also, unlike the first embodiment, the first four-way selector valve (31) has a first port connected to the discharge side of the compressor (11) and a second port connected to one end of the outdoor heat exchanger (21). The third port is connected to the suction side of the compressor (11), and the fourth port is connected to one end of the indoor heat exchanger (22). On the other hand, in the second four-way selector valve (33), the first port is connected to the liquid storage part (41) of the gas-liquid separator (40) via the separation liquid pipe (43), and the second port is the outdoor heat. The other port of the exchanger (21) is connected, the third port is connected to the heat transfer pipe (50) of the gas-liquid separator (40) via the liquid inflow pipe (45), and the fourth port is the indoor heat exchanger. It is connected to the other end of (22).

  These first and second four-way switching valves (31, 33) are configured to be switchable between the first and second states, as in the first embodiment. The first and second four-way switching valves (31, 33) constitute a refrigerant switching mechanism that switches the refrigerant circulation direction in order to switch between the cooling operation and the heating operation.

-Driving action-
Next, the operation | movement at the time of air_conditionaing | cooling operation and heating operation of the air conditioner (1) of Embodiment 2 is demonstrated.

(Cooling operation)
As shown in FIG. 6, during the cooling operation, the first four-way switching valve (31) is set to the first state, and the second four-way switching valve (33) is set to the second state. Further, the first electromagnetic open / close valve (34) is opened, and the second electromagnetic open / close valve (35) is closed. When the motor (13) is energized in this state, the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, the outdoor heat exchanger (21) serves as a radiator, and the indoor heat exchanger (22) serves as an evaporator. The high pressure of the refrigeration cycle is set higher than the critical pressure of carbon dioxide, which is a refrigerant.

  From the compressor (11), a supercritical high-pressure refrigerant is discharged. This high-pressure refrigerant flows into the outdoor heat exchanger (21) through the first four-way switching valve (31). In the outdoor heat exchanger (21), the high-pressure refrigerant radiates heat to the outdoor air.

  The high-pressure refrigerant radiated by the outdoor heat exchanger (21) passes through the second four-way switching valve (33) and the liquid inflow pipe (45) and then flows through the heat transfer pipe (50). At this time, the high-pressure refrigerant is cooled by exchanging heat with the liquid refrigerant stored in the liquid storage section (41) of the gas-liquid separator (40). The high-pressure refrigerant that has flowed out of the heat transfer tube (50) flows into the expander (12). In the expander (12), the high-pressure refrigerant expands, and the internal energy of the high-pressure refrigerant is converted into the rotational power of the compressor (11). Due to the expansion in the expander (12), the pressure of the high-pressure refrigerant decreases and changes from a supercritical state to a gas-liquid two-layer state.

  The low-pressure refrigerant decompressed by the expander (12) flows into the container of the gas-liquid separator (40). In the gas-liquid separator (40), the low-pressure refrigerant in the gas-liquid two-phase state is separated into liquid refrigerant and gas refrigerant. The low-pressure liquid refrigerant stored in the liquid storage part (41) is heated by exchanging heat with the high-pressure refrigerant flowing through the heat transfer tube (50). On the other hand, the low-pressure gas refrigerant stored in the gas storage part (42) is opened by the gas control valve (38) at a predetermined opening as appropriate, so that the compressor (11) passes through the separation gas pipe (44). It is returned to the suction side.

  The low-pressure liquid refrigerant in the liquid storage part (41) flows into the indoor heat exchanger (22) after passing through the separation liquid pipe (43) and the second four-way switching valve (33). In the indoor heat exchanger (22), the low-pressure refrigerant absorbs heat from the indoor air and evaporates. At this time, room air cooled by the low-pressure refrigerant is supplied into the room. The low-pressure refrigerant evaporated in the indoor heat exchanger (22) passes through the first four-way switching valve (31) and is sucked into the compressor (11).

(Heating operation)
As shown in FIG. 7, during the heating operation, the first four-way selector valve (31) is set to the second state, and the second four-way selector valve (33) is set to the first state. Further, the first electromagnetic on-off valve (34) is closed, and the second electromagnetic on-off valve (35) is opened. When the motor (13) is energized in this state, the refrigerant circulates in the refrigerant circuit (10) and a refrigeration cycle is performed. At that time, the indoor heat exchanger (22) serves as a radiator, and the outdoor heat exchanger (21) serves as an evaporator. The high pressure of the refrigeration cycle is set higher than the critical pressure of carbon dioxide, which is a refrigerant, as in the cooling operation.

  From the compressor (11), a supercritical high-pressure refrigerant is discharged. This high-pressure refrigerant flows into the indoor heat exchanger (22) through the first four-way switching valve (31). In the indoor heat exchanger (22), the high-pressure refrigerant radiates heat to the room air. At this time, room air heated by the high-pressure refrigerant is supplied into the room.

  The high-pressure refrigerant radiated by the indoor heat exchanger (22) flows into the expander (12) through the second four-way switching valve (33) and the bypass pipe (46). In the expander (12), the high-pressure refrigerant expands, and the internal energy of the high-pressure refrigerant is converted into the rotational power of the compressor (11). Due to the expansion in the expander (12), the pressure of the high-pressure refrigerant decreases and changes from a supercritical state to a gas-liquid two-layer state.

  The low-pressure refrigerant decompressed by the expander (12) flows into the container of the gas-liquid separator (40). In the gas-liquid separator (40), the low-pressure refrigerant in the gas-liquid two-phase state is separated into liquid refrigerant and gas refrigerant. At this time, since the refrigerant does not flow through the heat transfer tube (50), the liquid refrigerant in the liquid reservoir (41) is not heat-exchanged.

  The low-pressure liquid refrigerant in the liquid storage part (41) flows into the outdoor heat exchanger (21) after passing through the separation liquid pipe (43) and the second four-way switching valve (33). In the outdoor heat exchanger (21), the low-pressure refrigerant absorbs heat from the outdoor air and evaporates. The low-pressure refrigerant evaporated in the outdoor heat exchanger (21) passes through the first four-way switching valve (31) and is sucked into the compressor (11).

-Effect of Embodiment 2-
In the second embodiment, the state of the first and second electromagnetic opening / closing valves (34, 35) is switched, so that the heat exchange of the refrigerant is performed by the heat transfer tube (50) only during the cooling operation. During the cooling operation, the suction refrigerant density de of the expander (12) is increased. Therefore, the refrigerant mass flow rates (Mc and Me) of the compressor (11) and the expander (12) can be balanced, and a desired refrigeration cycle can be performed in the refrigerant circuit (10).

<Modification of Embodiment 2>
Next, a refrigeration apparatus according to a modification of the second embodiment will be described. The refrigeration apparatus of Modification 1 is provided with first and second motor-operated valves (36, 37) instead of the first and second electromagnetic on-off valves (34, 35) of the second embodiment. . Hereinafter, differences from the second embodiment will be described.

  As shown in FIG. 8, in the refrigerant circuit (10) of this modification, the liquid inflow pipe (45) is provided with a first motor-operated valve (36) having a variable opening. This 1st motor operated valve (36) is comprised so that adjustment of the refrigerant | coolant flow volume which distribute | circulates a heat exchanger tube (50) is possible. The bypass pipe (46) is provided with a second motor-operated valve (37) having a variable opening. This 2nd motor operated valve (37) is comprised so that adjustment of the refrigerant | coolant flow rate of a bypass pipe (46) is possible. The bypass pipe (46) and the first and second motor operated valves (36, 37) constitute a heat exchange amount adjusting mechanism (60) that changes the heat exchange amount of the refrigerant in the heat transfer pipe (50).

  In this modification, the flow rate of the refrigerant flowing through the heat transfer tube (50) is adjusted by adjusting the opening degree of the first and second motor operated valves (36, 37), and the heat of the refrigerant in the heat transfer tube (50) is adjusted. The exchange amount can be adjusted. Therefore, the refrigerant mass flow rates (Me and Mc) of the compressor (11) and the expander (12) can be balanced with high accuracy according to the operating conditions.

  Also, by setting the first motor-operated valve (36) to the fully open state and the second motor-operated valve (37) to the fully-closed state, the refrigerant flows through the heat transfer pipe (50) only during the cooling operation, and heat exchange of the refrigerant is performed. It can be carried out.

<< Embodiment 3 of the Invention >>
Next, the refrigeration apparatus of Embodiment 3 will be described. The refrigeration apparatus of Embodiment 3 is different from the refrigeration apparatus of Embodiment 1 in the configuration of the refrigerant circuit (10). Hereinafter, differences from the first embodiment will be described.

  As shown in FIG. 9, the refrigerant circuit (10) of the third embodiment is provided with a four-way switching valve (31) in the same manner as the first four-way switching valve of the first embodiment. One second four-way selector valve (32) is not provided. The four-way switching valve (31) constitutes a refrigerant switching mechanism that switches the circulation direction of the refrigerant in order to switch between the cooling operation and the heating operation.

  On the other hand, in this embodiment, the outdoor heat exchanger (21) and the indoor heat exchanger (22) are connected by the first pipe (71). The first pipe (71) is provided with a first check valve (81) near the outdoor heat exchanger (21) and a second check valve (82) near the indoor heat exchanger (22). Yes. In the first pipe (71), one end of a liquid inflow pipe (45) is connected between the outdoor heat exchanger (21) and the first check valve (81). The other end of the liquid inflow pipe (45) is connected to one end of the heat transfer pipe (50). The other end of the heat transfer tube (50) is connected to the suction side of the expander (12). The liquid inflow pipe (45) is provided with a third check valve (83).

  One end of the separation liquid pipe (43) of this embodiment is connected to the liquid storage part (41) of the gas-liquid separator (40), and the other end is a first check valve (81) in the first pipe (71). And the second check valve (82). In the first pipe (71), one end of the second pipe (72) is connected between the second check valve (82) and the indoor heat exchanger (22). The other end of the second pipe (72) is connected to a pipe between the suction side of the expander (12) and the gas-liquid separator (40). The second pipe (72) is provided with a fourth check valve (84).

  The first check valve (81) only allows the refrigerant to flow from the connection portion of the separation liquid pipe (43) to the connection portion of the liquid inflow pipe (45) in the first pipe (71). The second check valve (82) only allows the refrigerant to flow from the connection portion of the separation liquid pipe (43) to the connection portion of the second pipe (72) in the first pipe (71). The third check valve (83) only allows the refrigerant to flow from the first pipe (71) to the heat transfer pipe (50). The fourth check valve (84) only allows the refrigerant to flow from the first pipe (71) toward the suction side of the expander (12).

  As described above, the first pipe (71), the second pipe (72), the liquid inflow pipe (45), and the heat transfer pipe (50) are connected, and the check valve (81, 82, 83, 84) is connected to this circuit. In the refrigerant circuit (10) of the present embodiment, a circuit similar to a so-called bridge circuit is configured. This circuit constitutes a heat exchange amount adjusting mechanism (60) for changing the heat exchange amount of the refrigerant in the heat transfer tube (50), and the refrigerant flow in the heat transfer tube (50) is only during the cooling operation of the air conditioner (1). Let the heat exchange.

-Driving action-
Next, the operation | movement at the time of air_conditionaing | cooling operation and heating operation of the air conditioner (1) of Embodiment 3 is demonstrated.

(Cooling operation)
As shown in FIG. 10, during the cooling operation, the four-way selector valve (31) is set to the first state. When the motor (13) is energized in this state, the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, the outdoor heat exchanger (21) serves as a radiator, and the indoor heat exchanger (22) serves as an evaporator. The high pressure of the refrigeration cycle is set higher than the critical pressure of carbon dioxide, which is a refrigerant.

  From the compressor (11), a supercritical high-pressure refrigerant is discharged. This high-pressure refrigerant flows into the outdoor heat exchanger (21) through the four-way switching valve (31). In the outdoor heat exchanger (21), the high-pressure refrigerant radiates heat to the outdoor air.

  The high-pressure refrigerant radiated by the outdoor heat exchanger (21) passes through the third check valve (83) of the liquid inflow pipe (45) and flows through the heat transfer pipe (50). At this time, the high-pressure refrigerant is cooled by exchanging heat with the liquid refrigerant stored in the liquid storage section (41) of the gas-liquid separator (40). The high-pressure refrigerant that has flowed out of the heat transfer tube (50) flows into the expander (12). In the expander (12), the high-pressure refrigerant expands, and the internal energy of the high-pressure refrigerant is converted into the rotational power of the compressor (11). Due to the expansion in the expander (12), the pressure of the high-pressure refrigerant decreases and changes from a supercritical state to a gas-liquid two-layer state.

  The low-pressure refrigerant decompressed by the expander (12) flows into the container of the gas-liquid separator (40). At this time, the low-pressure refrigerant in the gas-liquid two-phase state is separated into liquid refrigerant and gas refrigerant. The low-pressure liquid refrigerant stored in the liquid storage part (41) is heated by exchanging heat with the high-pressure refrigerant flowing through the heat transfer tube (50). On the other hand, the low-pressure gas refrigerant stored in the gas storage part (42) is opened by the gas control valve (38) at a predetermined opening as appropriate, so that the compressor (11) passes through the separation gas pipe (44). It is returned to the suction side.

  The low-pressure liquid refrigerant in the liquid reservoir (41) passes through the second check valve (82) of the first pipe (71) via the separation liquid pipe (43) and flows into the indoor heat exchanger (22). To do. In the indoor heat exchanger (22), the low-pressure refrigerant absorbs heat from the indoor air and evaporates. At this time, room air cooled by the low-pressure refrigerant is supplied into the room. The low-pressure refrigerant evaporated in the indoor heat exchanger (22) passes through the four-way switching valve (31) and is sucked into the compressor (11).

(Heating operation)
As shown in FIG. 11, during the heating operation, the four-way selector valve (31) is set to the second state. When the motor (13) is energized in this state, the refrigerant circulates in the refrigerant circuit (10) and a refrigeration cycle is performed. At that time, the indoor heat exchanger (22) serves as a radiator, and the outdoor heat exchanger (21) serves as an evaporator. The high pressure of the refrigeration cycle is set higher than the critical pressure of carbon dioxide, which is a refrigerant, as in the cooling operation.

  From the compressor (11), a supercritical high-pressure refrigerant is discharged. This high-pressure refrigerant flows into the indoor heat exchanger (22) through the four-way switching valve (31). In the indoor heat exchanger (22), the high-pressure refrigerant radiates heat to the room air. At this time, room air heated by the high-pressure refrigerant is supplied into the room.

  The high-pressure refrigerant radiated by the indoor heat exchanger (22) passes through the first check valve (84) of the second pipe (72) via the first pipe (71) and flows into the expander (12). To do. In the expander (12), the high-pressure refrigerant expands, and the internal energy of the high-pressure refrigerant is converted into the rotational power of the compressor (11). Due to the expansion in the expander (12), the pressure of the high-pressure refrigerant decreases and changes from a supercritical state to a gas-liquid two-layer state.

  The low-pressure refrigerant decompressed by the expander (12) flows into the container of the gas-liquid separator (40). In the gas-liquid separator (40), the low-pressure refrigerant in the gas-liquid two-phase state is separated into liquid refrigerant and gas refrigerant. At this time, since the refrigerant does not flow through the heat transfer tube (50), the liquid refrigerant in the liquid storage section (41) is hardly subjected to heat exchange.

  The low-pressure liquid refrigerant in the liquid reservoir (41) passes through the first check valve (81) of the first pipe (72) via the separation liquid pipe (43) and flows into the outdoor heat exchanger (21). To do. In the outdoor heat exchanger (21), the low-pressure refrigerant absorbs heat from the outdoor air and evaporates. The low-pressure refrigerant evaporated in the outdoor heat exchanger (21) passes through the four-way switching valve (31) and is sucked into the compressor (11).

-Effect of Embodiment 3-
In Embodiment 3 described above, the heat exchange of the refrigerant is performed by the heat transfer pipe (50) only during the cooling operation by the combination of the predetermined piping path and the check valve (81, 82, 83, 84). During the cooling operation, the suction refrigerant density de of the expander (12) is increased. Therefore, the refrigerant mass flow rates (Mc and Me) of the compressor (11) and the expander (12) can be balanced, and a desired refrigeration cycle can be performed in the refrigerant circuit (10).

  Here, in this embodiment, the presence or absence of heat exchange of the refrigerant in the heat transfer tube (50) can be switched according to the switching between the cooling operation and the heating operation only by the switching control of the four-way switching valve (31). For this reason, the control operation in the refrigerant circuit (10) can be easily performed.

<< Other Embodiments >>
The present invention may be configured as follows with respect to the above embodiment.

  In the above embodiment, the gas refrigerant separated by the gas-liquid separator (40) can be sent to the suction side of the compressor (11) via the separation gas pipe (44). However, instead of this, or in addition to this, a liquid injection pipe for sending the liquid refrigerant separated by the gas-liquid separator (40) to the suction side of the compressor (11) may be provided.

  FIG. 12 is an example in which the liquid injection pipe (second injection pipe) (48) is provided in the refrigeration apparatus of the second embodiment. One end of the liquid injection pipe (48) is connected to the pipe between the liquid reservoir (41) and the second four-way selector valve (33), and the other end is connected to the suction pipe of the compressor (11). ing. The liquid injection pipe (48) is provided with a liquid control valve (39) for adjusting the refrigerant flow rate of the liquid injection pipe (48).

  With the above configuration, the liquid refrigerant separated by the gas-liquid separator (40) can be sent to the suction side of the compressor (11) via the liquid injection pipe (48) to perform so-called liquid injection. At this time, the degree of superheat of the refrigerant sucked in the compressor (11) can be adjusted by adjusting the liquid injection amount by the liquid control valve (39). Therefore, optimal refrigeration cycle control can be performed with this refrigeration apparatus. Further, finer refrigeration cycle control can be performed by combining gas injection through the gas injection pipe (44) and liquid injection through the liquid injection pipe (48). Further, the liquid injection pipe (48) allows the refrigerating machine oil contained in the refrigerant flowing out of the expander (12) to be introduced to the suction side of the compressor (11) together with the liquid refrigerant separated by the gas-liquid separator (40). It can also be used as a so-called oil return pipe.

  Moreover, in the said embodiment, although the compressor (11) and the expander (12) are comprised with the rotary piston type fluid machine, it is not restricted to this, For example, volumes, such as a scroll type, a swing type, a multi-vane type, etc. It may be configured by a fluid machine of a type, or may be configured by combining these positive displacement type fluid machines (including a rotary piston type).

  Furthermore, in the above embodiment, carbon dioxide is used as the refrigerant. However, the present invention is not limited to this, and natural refrigerants such as HFC refrigerant, HC refrigerant, water, air, and ammonia may be used.

  As described above, the present invention is useful for a refrigeration apparatus that includes a refrigerant circuit that compresses refrigerant and performs a vapor compression refrigeration cycle, and in which an expander and a compressor are mechanically connected.

It is a refrigerant circuit figure of the air conditioner concerning Embodiment 1 of the present invention. FIG. 3 is a refrigerant circuit diagram illustrating a refrigerant flow during a cooling operation according to the first embodiment. FIG. 3 is a refrigerant circuit diagram illustrating a refrigerant flow during heating operation of the first embodiment. FIG. 6 is a refrigerant circuit diagram of an air conditioner according to a modification of the first embodiment. 6 is a refrigerant circuit diagram of an air conditioner according to Embodiment 2. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow during a cooling operation of Embodiment 2. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow during heating operation of Embodiment 2. FIG. It is a refrigerant circuit figure of the air conditioner concerning the modification of Embodiment 2. It is a refrigerant circuit figure of the air conditioner concerning Embodiment 3. 6 is a refrigerant circuit diagram illustrating a refrigerant flow during a cooling operation of Embodiment 3. FIG. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow during heating operation of the third embodiment. It is a refrigerant circuit figure of the air conditioner concerning the modification of Embodiment 3.

Explanation of symbols

(1) Air conditioner
(10) Refrigerant circuit
(11) Compressor
(12) Expander
(13) Motor
(21) Outdoor heat exchanger (heat source side heat exchanger)
(22) Indoor heat exchanger (use side heat exchanger, 22a, 22b, 22c)
(31) Four-way switching valve (refrigerant switching mechanism)
(32) Four-way selector valve (heat exchange amount adjustment mechanism)
(33) Four-way switching valve (refrigerant switching mechanism)
(34) First solenoid valve
(35) Second solenoid valve
(36) First motor operated valve
(37) Second motor operated valve
(38) Gas control valve
(39) Fluid control valve
(40) Gas-liquid separator
(41) Liquid reservoir
(42) Gas reservoir
(44) Separation gas pipe (first injection pipe)
(46) Bypass pipe
(48) Liquid injection piping (second injection piping)
(50) Heat transfer tube (internal heat exchanger)
(60) Heat exchange adjustment mechanism
(61) Flow control valve (61a, 61b, 61c)
(81-84) Check valve

Claims (12)

A compressor (11), a heat source side heat exchanger (21), an expander (12), and a utilization side heat exchanger (22) are connected to each other, and a refrigerant circuit (10) for performing a refrigeration cycle is provided. 11) and an expander (12) are mechanically connected to each other to recover the expansion power of the expander (12),
A gas-liquid separator (40) for separating and temporarily storing the refrigerant expanded by the expander (12) into liquid refrigerant and gas refrigerant;
The gas-liquid separator (40) includes an internal heat exchange unit (50) for exchanging heat between the liquid refrigerant separated by the gas-liquid separator (40) and the refrigerant sucked into the expander (12). Refrigeration equipment. The refrigeration apparatus according to claim 1,
A refrigeration apparatus comprising a heat exchange amount adjustment mechanism (60) that changes the heat exchange amount of the refrigerant in the internal heat exchange unit (50) according to operating conditions. The refrigeration apparatus according to claim 1 or 2,
The gas-liquid separator (40) includes a liquid storage part (41) in which the separated liquid refrigerant is stored, and a refrigerant that is adjacent to the liquid storage part (41) and through which the refrigerant sucked into the expander (12) flows. With heat pipe (50),
The refrigeration apparatus in which the heat transfer tube (50) constitutes an internal heat exchange unit that exchanges heat between the liquid refrigerant in the liquid storage unit (41) and the refrigerant in the heat transfer tube (50). The refrigeration apparatus according to claim 2 or 3,
A refrigerant switching mechanism (31, 33) for switching between a cooling operation and a heating operation by changing the circulation direction of the refrigerant in the refrigerant circuit (10);
The heat exchange amount adjusting mechanism (60) is a refrigeration apparatus that performs heat exchange of the refrigerant in the internal heat exchange section (50) only during the cooling operation. The refrigeration apparatus according to claim 3 or 4,
The heat exchange amount adjusting mechanism (60) adjusts the flow rate of the refrigerant flowing through the heat transfer pipe (50) and the bypass pipe (46) for allowing the refrigerant to bypass the heat transfer pipe (50) and sucking it into the expander (12). A refrigeration apparatus including a first motor-operated valve (36) and a second motor-operated valve (37) that adjusts the refrigerant flow rate of the bypass pipe (46). The refrigeration apparatus according to claim 4,
The heat exchange amount adjusting mechanism (60) is a refrigeration apparatus including a four-way switching valve (32). The refrigeration apparatus according to claim 4,
The heat exchange amount adjusting mechanism (60) allows or prohibits the refrigerant flow in the heat transfer pipe (50) and the bypass pipe (46) that causes the refrigerant to bypass the heat transfer pipe (50) and be sucked into the expander (12). A refrigeration system comprising a first electromagnetic on-off valve (34) and a second electromagnetic on-off valve (35) that allows or prohibits the flow of refrigerant in the bypass pipe (46). The refrigeration apparatus according to claim 4,
The heat exchange amount adjusting mechanism (60) is a refrigeration apparatus configured by a combination of piping and check valves (81, 82, 83, 84). The refrigeration apparatus according to any one of claims 1 to 8,
The refrigerant circuit (10) includes a first injection pipe (44) for sending the gas refrigerant of the gas-liquid separator (40) to the suction side of the compressor (11), and a refrigerant flow rate of the first injection pipe (44). A refrigeration system comprising a gas control valve (38) to be adjusted. The refrigeration apparatus according to any one of claims 1 to 9,
In the refrigerant circuit (10), the refrigerant flow rate of the second injection pipe (48) for sending the liquid refrigerant of the gas-liquid separator (40) to the suction side of the compressor (11) and the second injection pipe (48) is set. A refrigeration system comprising a liquid control valve (39) for adjustment. The refrigeration apparatus according to any one of claims 1 to 10,
A plurality of usage-side heat exchangers (22a, 22b, 22c) are connected in parallel to the refrigerant circuit (10),
A refrigeration apparatus comprising a plurality of flow rate adjustment valves (61a, 61b, 61c) for adjusting the flow rates of refrigerant flowing into the use side heat exchangers (22a, 22b, 22c). The refrigeration apparatus according to any one of claims 1 to 11,
A refrigerating apparatus in which carbon dioxide is used as a refrigerant in the refrigerant circuit (10).

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