Patent Publication Number: US-2007101759-A1

Title: Refrigeration apparatus constructing method, and refrigeration apparatus

Description:
FIELD OF THE INVENTION  
      The present invention relates to a refrigeration apparatus constructing method and a refrigeration apparatus, and more particularly relates to a refrigeration apparatus constructing method, and a refrigeration apparatus comprising: a heat source unit comprising a compressor and a heat source side heat exchanger; a utilization unit comprising a utilization side heat exchanger; and a refrigerant connecting pipe that connects the heat source unit and the utilization unit.  
     BACKGROUND ART  
      An example of a conventional refrigeration apparatus is a separate type air conditioner. An air conditioner of this type principally comprises: a heat source unit comprising a compressor and a heat source side heat exchanger; a utilization unit comprising a utilization side heat exchanger; and a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe that connect these units.  
      In such an air conditioner, the series of construction steps, from the equipment installation, piping, and wiring work to the startup of operation principally comprises the following four processes:  
      (1) installing equipment, piping, and wiring work;  
      (2) drawing a vacuum in the refrigerant connecting pipe;  
      (3) filling supplementary refrigerant (performed as needed); and  
      (4) starting operation.  
      In the construction of an air conditioner as mentioned above, the work of drawing a vacuum in the refrigerant connecting pipe is important in order to prevent: the release of the refrigerant into the atmosphere; the deterioration of the refrigerant and the refrigerator oil due to residual oxygen gas; a rise in the operating pressure due to the noncondensable gas, whose principal component is an air component such as oxygen gas and nitrogen gas; and the like; however, there is a problem because it is necessary to perform troublesome work like connecting the vacuum pump to the liquid refrigerant connecting pipe and the gas refrigerant connecting pipe.  
      To solve this problem, an air conditioner has been proposed that, by connecting a gas separation apparatus filled with an adsorbent to a refrigerant circuit and circulating the refrigerant, adsorbs and eliminates from the refrigerant the noncondensable gas remaining inside the refrigerant connecting pipe after the equipment installation, piping, and wiring work. It is possible to omit the vacuum drawing work wherein a vacuum pump is used, thereby simplifying the construction of the air conditioner (e.g., refer to Patent Document 1). However, with this air conditioner, a large amount of the adsorbent is needed to enable the adsorption of as much of the noncondensable gas contained in the refrigerant as possible, which consequently increases the size of the overall apparatus, and actually makes it problematic to mount on the refrigeration apparatus.  
      In addition, an air conditioner has been proposed that: connects a jig comprising a separation membrane to the refrigerant circuit; fills the entire refrigerant circuit beforehand with a refrigerant sealed in the heat source unit; mixes the refrigerant and the noncondensable gas that remained inside the refrigerant connecting pipe after equipment installation, piping, and wiring work; subsequently supplies the separation membrane without raising the pressure of the refrigerant and the noncondensable gas mixture; and separates and eliminates the noncondensable gas. Thereby, it is possible to omit the vacuum drawing work wherein a vacuum pump is used, thereby simplifying the construction of the air conditioner (e.g., refer to Patent Document 2). However, with this air conditioner, the pressure differential cannot be increased between the separation membrane upstream side (i.e., inside the refrigerant circuit) and downstream side (i.e., outside the refrigerant circuit), which is a problem because of the low efficiency by which the separation membrane separates the noncondensable gas.  
      &lt;Patent Document 1&gt; 
      Published Unexamined Utility Model Application H05-69571  
      &lt;Patent Document 2&gt; 
      Japanese Published Patent Application No. H10-213363  
     DISCLOSURE OF THE INVENTION  
      It is an object of the present invention to improve the efficiency of separating a noncondensable gas with a separation membrane in a refrigeration apparatus constituted, for the purpose of omitting the vacuum drawing work, so that, by using a separation membrane, it can separate and eliminate the noncondensable gas, in a state mixed with a refrigerant inside a refrigerant circuit, that was left inside the refrigerant connecting pipe during on-site construction.  
      A refrigeration apparatus constructing method according to the first invention is a method of constructing a refrigeration apparatus, comprising: a heat source unit comprising a compressor and a heat source side heat exchanger; a utilization unit comprising a utilization side heat exchanger; and a liquid refrigerant connecting pipe that connects the heat source unit and the utilization unit; the method comprising the steps of an equipment installing step and a noncondensable gas discharging step. The equipment installing step constitutes a refrigerant circuit by installing the heat source unit and the utilization unit, and connecting the refrigerant connecting pipe. The noncondensable gas discharging step operates the compressor to circulate a refrigerant inside the refrigerant circuit, uses a membrane to separate a noncondensable gas remaining inside the refrigerant connecting pipe from the refrigerant flowing between the heat source side heat exchanger and the utilization side heat exchanger, and discharges the noncondensable gas out of the refrigerant circuit.  
      With this method of constructing the refrigeration apparatus, the equipment arranging step constitutes the refrigerant circuit by installing the heat source unit and the utilization unit and connecting the refrigerant connecting pipe; subsequently, the noncondensable gas discharging step raises the pressure of the refrigerant and the noncondensable gas, flowing between the heat source side heat exchanger and the utilization side heat exchanger, by operating the compressor and circulating the noncondensable gas remaining inside the refrigerant connecting pipe along with the refrigerant inside the refrigerant circuit, and using a membrane to separate from the noncondensable gas-containing refrigerant, whose pressure has been increased, the noncondensable gas and discharging it out of the refrigerant circuit. Thus, by operating the compressor and circulating the refrigerant, the pressure differential between the upstream side (i.e., inside the refrigerant circuit) and the downstream side (i.e., outside of the refrigerant circuit) of the separation membrane used in membrane separation can be increased, and the efficiency of separating the noncondensable gas in the separation membrane can consequently be improved.  
      A refrigeration apparatus constructing method according to the second invention is a method of constructing a refrigeration apparatus, comprising: a heat source unit comprising a compressor and a heat source side heat exchanger; a utilization unit comprising a utilization side heat exchanger; and a liquid refrigerant connecting pipe that connects the heat source unit and the utilization unit; the method comprising the steps of a refrigerant circuit constituting step and a noncondensable gas discharging step. The refrigerant circuit constituting step constitutes a refrigerant circuit by connecting the heat source unit and the utilization unit via the refrigerant connecting pipe. The noncondensable gas discharging step operates the compressor to circulate a refrigerant inside the refrigerant circuit, uses a separation membrane to separate a noncondensable gas remaining inside the refrigerant connecting pipe from the refrigerant flowing between the heat source side heat exchanger and the utilization side heat exchanger, and discharges the noncondensable gas out of the refrigerant circuit.  
      With this method of constructing the refrigeration apparatus, the refrigerant circuit constituting step connects the heat source unit and the utilization unit via the refrigerant connecting pipe; subsequently, the noncondensable gas discharging step raises the pressure of the refrigerant and the noncondensable gas, flowing between the heat source side heat exchanger and the utilization side heat exchanger, by operating the compressor and circulating the noncondensable gas remaining inside the refrigerant connecting pipe along with the refrigerant inside the refrigerant circuit, and using a separation membrane to separate the noncondensable gas from the noncondensable gas-containing refrigerant, whose pressure has been increased, and discharging it out of the refrigerant circuit. Thus, by operating the compressor and circulating the refrigerant, the pressure differential between the upstream side (i.e., inside the refrigerant circuit) and the downstream side (i.e., outside of the refrigerant circuit) of the separation membrane used in membrane separation can be increased, and the efficiency of separating the noncondensable gas in the separation membrane can consequently be improved.  
      A refrigeration apparatus constructing method according to the third invention is a refrigeration apparatus constructing method as recited in the first or second invention, wherein, in the noncondensable gas discharging step, the refrigerant flowing between the heat source side heat exchanger and the utilization side heat exchanger is vapor-liquid separated into liquid refrigerant and the noncondensable gas-containing gas refrigerant, and the noncondensable gas is subsequently separated from the vapor-liquid separated gas refrigerant.  
      With this method of constructing the refrigeration apparatus, the refrigerant flowing between the heat source side heat exchanger and the utilization side heat exchanger is gas-liquid separated into noncondensable gas-containing gas refrigerant and liquid refrigerant, and the amount of gas processed by membrane separation is reduced, thereby enabling a reduction in the size of a gas separation apparatus.  
      A refrigeration apparatus constructing method according to the fourth invention is a refrigeration apparatus constructing method as recited in the third invention, wherein in the noncondensable gas discharging step, the separated noncondensable gas is released into the atmosphere.  
      Because a vessel, and the like, that accumulates the separated noncondensable gas is no longer necessary with this method of constructing the refrigeration apparatus, the size of the gas separation apparatus that performs membrane separation can be further reduced.  
      A refrigeration apparatus constructing method according to the fifth invention is a invention through the fourth invention, further comprising: a seal testing step that, before the noncondensable gas discharging step, performs a seal test on the refrigerant connecting pipe; and a sealed gas releasing step that, after the seal testing step, reduces pressure by releasing a sealed gas inside the refrigerant connecting pipe into the atmosphere.  
      With this method of constructing the refrigeration apparatus, a seal test is performed on the refrigerant connecting pipe using the sealed gas, such as nitrogen gas, and the sealed gas is released into the atmosphere; consequently, the amount of oxygen gas remaining inside the refrigerant connecting pipe after these steps is reduced. Thereby, because the amount of oxygen gas circulating inside the refrigerant circuit together with the refrigerant can be reduced, the risk of a problem like deterioration of the refrigerant or the refrigerator oil can be eliminated.  
      The refrigeration apparatus according to the sixth invention is a refrigeration apparatus that constitutes a refrigerant circuit, wherein a heat source unit comprising a compressor and a heat source side heat exchanger, and a utilization unit comprising a utilization side heat exchanger, are connected via a refrigerant connecting pipe, comprising: a gas separation apparatus comprising a separation membrane connected to a liquid side refrigerant circuit that connects the heat source side heat exchanger and the utilization side heat exchanger, and that is capable of separating from the refrigerant and discharging out of the refrigerant circuit the noncondensable gas remaining inside the refrigerant connecting pipe by operating the compressor and circulating the refrigerant inside the refrigerant circuit.  
      With this refrigeration apparatus, the heat source unit and the utilization unit are connected via the refrigerant connecting pipe; subsequently, the pressure of the refrigerant and the noncondensable gas, flowing between the heat source side heat exchanger and the utilization side heat exchanger, is raised by operating the compressor and circulating the noncondensable gas, whose principal component is an air component such as oxygen gas and nitrogen gas, remaining inside the refrigerant connecting pipe along with the refrigerant inside the refrigerant circuit; a separation apparatus having a separation membrane is used to separate the noncondensable gas from the noncondensable gas-containing refrigerant, whose pressure has been increased; and the noncondensable gas is then discharged out of the refrigerant circuit. Thereby, by operating the compressor and circulating the refrigerant, the pressure differential between the upstream side (i.e., inside the refrigerant circuit) and the downstream side (i.e., outside of the refrigerant circuit) of the separation membrane increases, and the efficiency of separating the noncondensable gas in the separation membrane can consequently be improved.  
      The refrigeration apparatus according to the seventh invention is a refrigeration apparatus as recited in the sixth invention, wherein the liquid side refrigerant circuit further comprises a receiver capable of accumulating the refrigerant flowing between the heat source side heat exchanger and the utilization side heat exchanger. The gas separation apparatus is connected to the receiver, and separates the noncondensable gas contained in the gas refrigerant accumulated in the upper part of the receiver.  
      With this refrigeration apparatus, the gas separation apparatus is connected to the receiver provided in the liquid side refrigerant circuit, the refrigerant flowing through the liquid side refrigerant circuit is gas-liquid separated into noncondensable gas-containing gas refrigerant and liquid refrigerant, the amount of processed gas is reduced, and the gas separation apparatus can subsequently separate the noncondensable gas, consequently reducing the size of the gas separation apparatus.  
      The refrigeration apparatus according to the eighth invention is a refrigeration apparatus as recited in the seventh invention, wherein the gas separation apparatus further comprises a discharge valve for releasing the separated noncondensable gas into the atmosphere.  
      Because a vessel, and the like, that accumulates the separated noncondensable gas is no longer necessary with this refrigeration apparatus, the size of the gas separation apparatus can be further reduced. 
    
    
     BRIEF EXPLANATION OF DRAWINGS  
       FIG. 1  is a schematic view of a refrigerant circuit of an air conditioner that serves as a refrigeration apparatus according to the first embodiment of the present invention.  
       FIG. 2  depicts the schematic structure of a receiver and a gas separation apparatus of the air conditioner according to the first embodiment.  
       FIG. 3  lists the molecular weight data for various gases.  
       FIG. 4  is a schematic view of the refrigerant circuit of the air conditioner according to a first modified example of the first embodiment.  
       FIG. 5  is a schematic view of the refrigerant circuit of the air conditioner according to a second modified example of the first embodiment.  
       FIG. 6  depicts the schematic structure of the receiver and the gas separation apparatus of the air conditioner according to the second modified example of the first embodiment.  
       FIG. 7  is a schematic view of the refrigerant circuit of the air conditioner that serves as the refrigeration apparatus according to the second embodiment of the present invention.  
       FIG. 8  is a schematic view of the refrigerant circuit of the air conditioner according to a first modified example of the second embodiment.  
       FIG. 9  is a schematic view of the refrigerant circuit of the air conditioner that serves as the refrigeration apparatus according to the third embodiment of the present invention.  
       FIG. 10  depicts the schematic structure of a separation membrane apparatus of the air conditioner according to the third embodiment.  
       FIG. 11  is a schematic view of the refrigerant circuit of the air conditioner according to a first modified example of the third embodiment.  
       FIG. 12  is a schematic view of the refrigerant circuit of the air conditioner according to a second modified example of the third embodiment.  
       FIG. 13  is a schematic view of the refrigerant circuit of the air conditioner that serves as the refrigeration apparatus according to the fourth embodiment of the present invention. 
    
    
     PREFERRED EMBODIMENTS  
      The following explains the embodiments of a refrigeration apparatus constructing method and refrigeration apparatus according to the present invention, based on the drawings.  
     First Embodiment  
      (1) Constitution of an Air Conditioner  
       FIG. 1  is a schematic view of a refrigerant circuit of an air conditioner  1  as one example of a refrigeration apparatus according to the first embodiment of the present invention. The air conditioner  1  in the present embodiment is a cooling dedicated air conditioner, and comprises a heat source unit  2 , a utilization unit  5 , and a liquid refrigerant connecting pipe  6  and a gas refrigerant connecting pipe  7  that connect the heat source unit  2  and the utilization unit  5 .  
      The utilization unit  5  principally comprises a utilization side heat exchanger  51 .  
      The utilization side heat exchanger  51  is equipment capable of cooling the air inside a room by a refrigerant that flows therewithin.  
      The heat source unit  2  principally comprises a compressor  21 , a heat source side heat exchanger  23 , a heat source side expansion valve  26 , a liquid side gate valve  27 , and a gas side gate valve  28 .  
      The compressor  21  is equipment for compressing the gas refrigerant that is taken in.  
      The heat source side heat exchanger  23  is equipment capable of condensing the refrigerant using air or water as a heat source. The heat source side expansion valve  26  is connected on the exit side of the heat source side heat exchanger  23  for regulating the refrigerant pressure, the refrigerant flow, and the like. The liquid side gate valve  27  and the gas side gate valve  28  are connected to the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , respectively.  
      The liquid refrigerant connecting pipe  6  is connected between the entrance side of the utilization side heat exchanger  51  of the utilization unit  5  and the exit side of the heat source side heat exchanger  23  of the heat source unit  2 . The gas refrigerant connecting pipe  7  is connected between the exit side of the utilization side heat exchanger  51  of the utilization unit  5  and the intake side of the compressor  21  of the heat source unit  2 . The liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  are, for example, the refrigerant connecting pipes constructed on-site when newly constructing an air conditioner  1 , or the refrigerant connecting pipes diverted from an existing air conditioner when replacing just the heat source unit  2  and the utilization unit  5 .  
      Here, the refrigerant circuit that ranges from the utilization side heat exchanger  51  to the heat source side heat exchanger  23 , including the liquid refrigerant connecting pipe  6 , the liquid side gate valve  27 , and the heat source side expansion valve  26 , is a liquid side refrigerant circuit  11 . In addition, the refrigerant circuit that ranges from the utilization side heat exchanger  51  to the heat source side heat exchanger  23 , including the gas refrigerant connecting pipe  7 , the gas side gate valve  28 , and the compressor  21 , is a gas side refrigerant circuit  12 . Namely, a refrigerant circuit  10  of the air conditioner  1  comprises the liquid side refrigerant circuit  11  and the gas side refrigerant circuit  12 .  
      In the present embodiment, the air conditioner  1  further comprises a receiver  25  provided in the liquid side refrigerant circuit  11 . More specifically, it is provided between the heat source side heat exchanger  23  and the heat source side expansion valve  26 . The receiver  25  is capable of accumulating the refrigerant condensed by the heat source side heat exchanger  23 . Furthermore, the liquid refrigerant condensed by the heat source side heat exchanger  23  flows outward from the lower part of the receiver  25 , and is sent to the heat source side expansion valve  26 . Consequently, the gas refrigerant not condensed by the heat source side heat exchanger  23  is gas-liquid separated inside the receiver  25 , and accumulates in the upper part of the receiver  25  (refer to  FIG. 2 ).  
      The air conditioner  1  further comprises a gas separation apparatus  31  connected to the liquid side refrigerant circuit  11 . In the present embodiment, the gas separation apparatus  31  principally comprises a separation membrane apparatus  34 .  
      By operating the compressor  21  and circulating the refrigerant inside the refrigerant circuit  10 , the separation membrane apparatus  34  can discharge from the refrigerant to outside of the refrigerant circuit  10  the noncondensable gas remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 . Here, the noncondensable gas is a gas whose principal component is an air component, such as oxygen gas and nitrogen gas. Consequently, if the refrigerant is circulated inside the refrigerant circuit  10 , it flows into the receiver  25  without being condensed in the heat source side heat exchanger  23 , and accumulates along with the gas refrigerant in the upper part of the receiver  25 .  
      In the present embodiment, the separation membrane apparatus  34  is equipment provided integrally with the upper part of the receiver  25 , and, as depicted in  FIG. 2 , comprises: a container main body  34   a  wherein one part is in communication with the upper part of the receiver  25 ; a separation membrane  34   b  disposed so that it splits the space inside the container main body  34   a  into a space S 1  and a space S 2 ; and a discharge valve  34   c  connected to the space S 2 .  
      The separation membrane  34   b , which is called a porous membrane, is made of a material such as a polyimide membrane, a cellulose acetate membrane, a polysulfone membrane, and a carbon membrane, and has a function wherein water vapor, oxygen gas, nitrogen gas, and the like, which are components that have comparatively small molecular weights, permeate, but the gas refrigerant, which has a large molecular weight, does not. Here, the porous membrane has numerous extremely fine pores, and the gas inside these pores separate when passing through, depending on the speed differential, i.e., components having a small molecular diameter permeate, but components having a large molecular diameter do not. For example, because the molecular weights (more specifically, the molecular diameters) of the R22 and R134a, as well as the molecular weights of the R32 and R125 contained in the mixed refrigerants R407C and R410A, which are used as refrigerants in the air conditioner, are larger than the molecular weights (more specifically, the molecular diameters) of any of the water vapor, oxygen gas, and nitrogen gas, as depicted in  FIG. 3 , they can be separated by the separation membrane  34   b . The space S 1  is in communication with the upper part of the receiver  25 . The space S 2  is the space into which flows the air component that permeated the separation membrane  34   b . The discharge valve  34   c  is provided for opening the space S 2  to the atmosphere, and is capable of releasing the air component (such as oxygen gas and nitrogen gas, which permeated the separation membrane  34   b  and flowed into the space S 2 ) from the space S 2  into the atmosphere.  
      ( 2 ) Method of Constructing the Air Conditioner  
      The following explains the method of constructing the air conditioner  1 .  
      &lt;Equipment Installing Step (Refrigerant Circuit Constituting Step)&gt; 
      The air conditioner  1  and the refrigerant circuit  10  are constituted by first emplacing the newly equipped utilization unit  5  and the heat source unit  2 , installing the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , and connecting the utilization unit  5  and the heat source unit  2 . At this point, the liquid side gate valve  27  and the gas side gate valve  28  of the newly equipped heat source unit  2  are shut off, and the refrigerant circuit of the heat source unit  2  is pre-filled with a predetermined amount of the refrigerant. Furthermore, the discharge valve  34   c  of the separation membrane apparatus  34  is shut off.  
      Furthermore, if replacing the utilization unit  5 , the heat source unit  2 , or both by diverting the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  that constitute an existing air conditioner, then, in the procedure mentioned above, only the utilization unit  5  and the heat source unit  2  are newly emplaced.  
      &lt;Seal Testing Step&gt; 
      A seal test is performed on the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  after constituting the refrigerant circuit  10  of the air conditioner  1 . However, if the utilization unit  5  is not provided with a gate valve, and the like, for the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , then the seal test is performed on the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  in a state connected to the utilization unit  5 .  
      First, nitrogen gas is supplied as the seal test gas from a supply port (not shown), which is provided in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , and the like, to a seal test portion, which includes the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , and the pressure of the seal test portion is then raised to the seal test pressure. Furthermore, after the supply of the nitrogen gas stops, it is verified whether the seal test portion holds the seal test pressure for the prescribed test time.  
      &lt;Sealed Gas Releasing Step&gt; 
      After the seal test has ended, the ambient gas (the sealed gas) in the seal test portion is released into the atmosphere to reduce the pressure in the seal test portion. At this point, because the ambient gas in the seal test portion contains a large amount of nitrogen gas that was used in the seal test, the greater part of the ambient gas in the seal test portion is substituted by nitrogen gas after being released into the atmosphere, thereby reducing the amount of oxygen gas. Additionally, to prevent the infiltration of air from outside of the refrigerant circuit  10  when performing the work of releasing the ambient gas into the atmosphere, the pressure in the seal test portion, which includes the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , is reduced to a pressure slightly higher than atmospheric pressure.  
      &lt;Noncondensable Gas Discharging Step&gt; 
      The liquid side gate valve  27  and the gas side gate valve  28  of the heat source unit  2  are opened, after the sealed gas has been released, creating a state wherein the refrigerant circuit of the utilization unit  5  and the refrigerant circuit of the heat source unit  2  are connected. Thereby, the refrigerant that was pre-filled in the heat source unit  2  is supplied to the entire refrigerant circuit  10 . However, if the required refrigerant fill quantity is insufficient with just the amount of refrigerant pre-filled in the heat source unit  2 , e.g., in the case wherein the refrigerant connecting pipes  6 ,  7  are long, then refrigerant can be externally supplemented and then filled as needed. Furthermore, if the heat source unit  2  is not pre-filled with refrigerant, then the entire amount of the refrigerant needed is externally filled. Thereby, the sealed gas (containing the noncondensable gas remaining in the utilization unit  5  if simultaneously performing the seal test on the utilization unit  5 ), which serves as the noncondensable gas remaining in the refrigerant connecting pipes  6 ,  7  after the sealed gas releasing step, is mixed with the refrigerant inside the refrigerant circuit  10 .  
      In this circuit configuration, operation is performed by activating the compressor  21  and circulating the refrigerant inside the refrigerant circuit  10 , the same as in normal operation. At this time, the opening of the heat source side expansion valve  26  is regulated to bring the pressure in the range from the discharge side of the compressor  21  to the heat source side expansion valve  26  of the liquid side refrigerant circuit  11  to the condensing pressure of the refrigerant. Namely, the pressure in the receiver  25  is raised to the condensing pressure of the refrigerant. Thereby, refrigerant in a saturated, gas-liquid mixed phase, which contains the noncondensable gas (the air component largely containing nitrogen gas) remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  after releasing the sealed gas, flows into the receiver  25 . The refrigerant that flows into the receiver  25  is gas-liquid separated into liquid refrigerant and gas refrigerant, which contains noncondensable gas. Moreover, the gas refrigerant containing noncondensable gas accumulates in the upper part space of the receiver  25 , and the liquid refrigerant flows out from the lower part of the receiver  25  and is sent to the heat source side expansion valve  26 .  
      In this state, the discharge valve  34   c  of the separation membrane apparatus  34  opens, and the space S 2  of the separation membrane apparatus  34  transitions to the opened to the atmosphere state. In so doing, the space S 1  is in communication with the upper part of the receiver  25 , and a pressure differential, corresponding to the pressure differential between the atmospheric pressure and the condensing pressure of the refrigerant, consequently arises between the space S 1  and the space S 2 . This pressure differential creates a propulsive force, and the noncondensable gas contained in the gas refrigerant remaining in the space S 1  permeates the separation membrane  34   b , flows to the space S 2  side, and is released into the atmosphere. However, the gas refrigerant transitions to a state wherein it remains inside the receiver  25 , without permeating the separation membrane  34   b . When this operation is performed for the prescribed time, the noncondensable gas, remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 , is discharged from the interior of the refrigerant circuit  10 .  
      In performing the above, the noncondensable gas is discharged from the interior of the refrigerant circuit  10 , and the discharge valve  34   c  of the separation membrane apparatus  34  is subsequently closed.  
      (3) Features of the Air Conditioner, and its Method of Construction  
      In the present embodiment, the air conditioner  1  and its method of construction have the following features.  
      (A)  
      In the air conditioner  1  of the present embodiment, the gas separation apparatus  31  comprising the separation membrane  34   b  is connected to the liquid side refrigerant circuit  11 ; therein, the noncondensable gas, such as oxygen gas and nitrogen gas remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  after the equipment installing step (the refrigerant circuit constituting step), is separated by a membrane, and can be discharged out of the refrigerant circuit  10 ; consequently, the size of the gas separation apparatus  31  can be reduced compared with the conventional case that uses a gas separation apparatus that utilizes large amounts of adsorbent. Thereby, the vacuum drawing work can be omitted during construction without increasing the overall size of the refrigeration apparatus (the heat source unit  2  in the present embodiment).  
      (B)  
      In the air conditioner  1 , the heat source unit  2  and the utilization unit  5  are connected, via the refrigerant connecting pipes  6 ,  7  in the equipment installing step (the refrigerant circuit constituting step); subsequently, in the noncondensable gas discharging step, the noncondensable gas remaining in the refrigerant connecting pipes  6 ,  7  is circulated along with the refrigerant inside the refrigerant circuit  10  by operating the compressor  21  (specifically, cooling operation or heating operation), thereby raising the pressure of the refrigerant and the noncondensable gas flowing between the heat source side heat exchanger  23  and the utilization side heat exchanger  51 , separating the noncondensable gas from the noncondensable gas-containing refrigerant, whose pressure has been increased, using the gas separation apparatus  31 , and discharging the noncondensable gas out of the refrigerant circuit  10 . It is possible to improve the separation efficiency of the noncondensable gas in the separation membrane  34   b  because it is possible to increase the pressure differential between the upstream side (i.e., the space S 1  side) and the downstream side (i.e., the space S 2  side) of the separation membrane  34   b  of the separation membrane apparatus  34  that constitutes the gas separation apparatus  31 .  
      (C)  
      In addition, in the air conditioner  1 , the size of the gas separation apparatus  31  can be reduced because the gas separation apparatus  31  is connected to the receiver  25  (in the present embodiment, provided integrally with the receiver  25 ) provided in the liquid side refrigerant circuit  11 , the refrigerant flowing in the liquid side refrigerant circuit  11  is gas-liquid separated into liquid refrigerant and noncondensable gas-containing gas refrigerant, the amount of processed gas is reduced, and the gas separation apparatus  31  can subsequently separate and discharge the noncondensable gas.  
      In addition, the air conditioner  1  further comprises a discharge valve  34   c  that discharges the noncondensable gas separated by the gas separation apparatus  31 , consequently making the vessel, and the like, that accumulates the separated noncondensable gas unnecessary, thereby enabling a further reduction in the size of the gas separation apparatus that performs membrane separation.  
      (D)  
      With the method of constructing the air conditioner  1 , the seal test of the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  is performed using the sealed gas, such as nitrogen gas, and the sealed gas is released into the atmosphere; consequently, it is possible after these steps to reduce the amount of oxygen gas remaining inside the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7 . Thereby, the amount of oxygen gas circulating together with the refrigerant inside the refrigerant circuit  10  can be reduced, and it is possible to eliminate the risk of problems, such as deterioration in the refrigerant or the refrigerator oil.  
     (4) Modified Example 1  
      Because the gas separation apparatus  31  of the abovementioned embodiments is provided so that the noncondensable gas is separated from the gas refrigerant in the upper part of the receiver  25 , it is possible to separate and eliminate moisture in the gas refrigerant inside the receiver  25  that exists as water vapor, but it is not possible to separate and eliminate the moisture that exists in the liquid refrigerant.  
      Consequently, as a result of a large amount of moisture unfortunately remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  due to, for example, the circumstances in which the piping is constructed, it is possible that a case may arise in which the moisture, along with the noncondensable gas, such as nitrogen gas or oxygen gas, cannot be eliminated from inside the refrigerant circuit  10  to a level that allows operation.  
      To prevent this, the separation membrane apparatus  34  may be connected to the receiver  25 , and a dryer  44  may be connected to the liquid side refrigerant circuit  11 , as in a gas separation apparatus  131  incorporated in a heat source unit  102  of an air conditioner  101  of the present modified example depicted in  FIG. 4 . Furthermore, in  FIG. 4 , the dryer  44  is connected to the upstream side of the receiver  25 , i.e., between the heat source side heat exchanger  23  and the receiver  25 , but may also be connected to the downstream side of the receiver  25 , i.e., between the receiver  25  and the heat source side expansion valve  26 .  
      Thereby, the noncondensable gas can be separated and discharged, and the moisture remaining inside the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  can be reliably eliminated from inside the refrigerant circuit  10  to a level that allows operation.  
     (5) Modified Example 2  
      With the abovementioned gas separation apparatuses  31 ,  131 , the separation membrane apparatus  34  is constituted integrally with the receiver  25 ; however, the separation membrane apparatus  34  may be connected to the upper part of the receiver  25  via a gas refrigerant introduction circuit  238 , as in a gas separation apparatus  231  incorporated in a heat source unit  202  of an air conditioner  201  in the present modified example depicted in  FIG. 5  and  FIG. 6 . Here, the gas refrigerant introduction circuit  238  is a conduit for introducing to the separation membrane apparatus  34  the noncondensable gas-containing gas refrigerant that accumulated in the upper part of the receiver  25 , and comprises a gas refrigerant introduction valve  238   a  for distributing and shutting off the noncondensable gas-containing gas refrigerant introduced to the separation membrane apparatus  34  from the upper part of the receiver  25 .  
      Furthermore, with the gas separation apparatus  231 , the operation of discharging the sealed gas, which serves as the noncondensable gas, from inside the refrigerant circuit  10  is performed by the following procedure. First, the gas refrigerant introduction valve  238   a  is opened, and the noncondensable gas-containing gas refrigerant (supply gas) that accumulated in the upper part of the receiver  25  is introduced to the separation membrane apparatus  34 . Then, the discharge valve  34   c  of the separation membrane apparatus  34  is opened, and the space S 2  of the separation membrane apparatus  34  transitions to the opened to the atmosphere state. In so doing, because the space S 1  of the separation membrane apparatus  34  is in communication with the upper part of the receiver  25 , a pressure differential arises between the space S 1  and the space S 2  corresponding to the pressure differential between the atmospheric pressure and the condensing pressure of the refrigerant. Consequently, this pressure differential forms a propulsive force, the noncondensable gas contained in the supply gas inside the space S 1  permeates the separation membrane  34   b , flows to the space S 2  side, and is then released into the atmosphere through the discharge valve  34   c . However, the gas refrigerant contained in the supply gas transitions to a state where it accumulates inside the space S 1 , without permeating the separation membrane  34   b . When this operation is executed for the prescribed time, the noncondensable gas remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  is discharged from the interior of the refrigerant circuit  10 . Then, after the noncondensable gas has been discharged from the interior of the refrigerant circuit  10 , the gas refrigerant introduction valve  238   a  and the discharge valve  34   c  that constitute the gas separation apparatus  231  are both shut off.  
     Second Embodiment  
      (1) Constitution of the Air Conditioner  
       FIG. 7  is a schematic view of the refrigerant circuit of an air conditioner  501  as one example of the refrigeration apparatus according to the second embodiment of the present invention. The air conditioner  501  is capable of cooling operation and heating operation in the present embodiment, and comprises a heat source unit  502 , the utilization unit  5 , and the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  for connecting the heat source unit  502  and the utilization unit  5 . Furthermore, the constitutions of the utilization unit  5  and the refrigerant connecting pipes  6 ,  7  of the air conditioner  501  in the present embodiment are the same as the utilization unit  5  and the refrigerant connecting pipes  6 ,  7  of the first embodiment and its modified examples, and their explanations are therefore omitted.  
      The heat source unit  502  principally comprises the compressor  21 , a four-way switching valve  522 , the heat source side heat exchanger  23 , a bridge circuit  524 , a receiver  25 , a heat source side expansion valve  26 , a liquid side gate valve  27 , and a gas side gate valve  28 . Namely, the heat source unit  502  of the present embodiment, in addition to the constitution of the heat source units  2 ,  102 ,  202  of the first embodiment and its modified examples, comprises the four-way switching valve  522  and the bridge circuit  524 , and both the utilization side heat exchanger  51  and the heat source side heat exchanger  23  function as a condenser and an evaporator of the refrigerant. The following explains the four-way switching valve  522  and the bridge circuit  524 .  
      The function of the four-way switching valve  522  is to switch the direction of the refrigerant flow when changing between cooling operation and heating operation; during cooling operation, the discharge side of the compressor  21  and the gas side of the heat source side heat exchanger  23  can be connected, and the intake side of the compressor  21  and the gas side gate valve  28  can be connected. During heating operation, the discharge side of the compressor  21  and the gas side gate valve  28  can be connected, and the intake side of the compressor  21  and the gas side of the heat source side heat exchanger  23  can be connected.  
      The bridge circuit  524  comprises four check valves  524   a - 524   d , and is connected between the heat source side heat exchanger  23  and the liquid side gate valve  27 . Here, a check valve  524   a  permits only the distribution of the refrigerant from the heat source side heat exchanger  23  to the receiver  25 . A check valve  524   b  permits only the distribution of the refrigerant from the liquid side gate valve  27  to the receiver  25 . A check valve  524   c  permits only the distribution of the refrigerant from the receiver  25  to the liquid side gate valve  27 . A check valve  524   d  permits only the distribution of the refrigerant from the receiver  25  to the heat source side heat exchanger  23 . Thereby, when the refrigerant flows from the heat source side heat exchanger  23  side toward the utilization side heat exchanger  51  side as during cooling operation, the bridge circuit  524  functions so that the refrigerant is flowed through the entrance of and into the receiver  25 , and the refrigerant flowing out of the exit of the receiver  25  flows toward the utilization side heat exchanger  51  side after expanding in the heat source side expansion valve  26 ; additionally, when the refrigerant flows from the utilization side heat exchanger  51  side toward the heat source side heat exchanger  23  side as during heating operation, the bridge circuit  524  functions so that the refrigerant flows through the entrance of and into the receiver  25 , and the refrigerant flowing out of the exit of the receiver  25  flows toward the heat source side heat exchanger  23  side after expanding in the heat source side expansion valve  26 .  
      Here, a liquid side refrigerant circuit  511  comprises the refrigerant circuit that ranges from the utilization side heat exchanger  51  to the heat source side heat exchanger  23 , including the liquid refrigerant connecting pipe  6 , the liquid side gate valve  27 , the bridge circuit  524 , the receiver  25 , and the heat source side expansion valve  26 . In addition, a gas side refrigerant circuit  512  comprises the refrigerant circuit ranging from the utilization side heat exchanger  51  to the heat source side heat exchanger  23 , including the gas refrigerant connecting pipe  7 , the gas side gate valve  28 , the four-way switching valve  522 , and the compressor  21 . In other words, a refrigerant circuit  510  of the air conditioner  501  comprises the liquid side refrigerant circuit  511  and the gas side refrigerant circuit  512 .  
      The air conditioner  501  further comprises the gas separation apparatus  231 , which is connected to the liquid side refrigerant circuit  511 . The gas separation apparatus  231  is the same as the gas separation apparatus  231  in the modified example of the first embodiment, and its explanation is therefore omitted.  
      (2) Method of Constructing the Air Conditioner  
      The following explains the method of constructing the air conditioner  501 . Furthermore, excepting the noncondensable gas discharging step, the procedure is the same as the air conditioner  1  constructing method of the first embodiment, and its explanation is therefore omitted.  
      &lt;Noncondensable Gas Discharging Step&gt; 
      The liquid side gate valve  27  and the gas side gate valve  28  of the heat source unit  502  are opened, after the sealed gas has been released, creating a state wherein the refrigerant circuit of the utilization unit  5  and the refrigerant circuit of the heat source unit  502  are connected. Thereby, the refrigerant that was pre-filled in the heat source unit  502  is supplied to the entire refrigerant circuit  510 . However, if the required refrigerant fill quantity is not met with just the amount of refrigerant pre-filled in the heat source unit  502 , e.g., if the refrigerant connecting pipes  6 ,  7  are long, then refrigerant can be externally supplemented and then filled as needed. Furthermore, if the heat source unit  502  is not pre-filled with refrigerant, then the entire amount of the refrigerant needed is externally filled. Thereby, the sealed gas (containing the noncondensable gas remaining in the utilization unit  5  if simultaneously performing the seal test on the utilization unit  5 ), which serves as the noncondensable gas remaining in the refrigerant connecting pipes  6 ,  7  after the sealed gas releasing step, is mixed with the refrigerant inside the refrigerant circuit  510 .  
      In this circuit configuration, operation is performed by activating the compressor  21  and circulating the refrigerant inside the refrigerant circuit  510 .  
      (Case of Discharging Noncondensable Gas While Performing Cooling Operation)  
      First, the case of performing the operation that circulates the refrigerant inside the refrigerant circuit  510  by the cooling operation will be explained. At this time, the four-way switching valve  522  is in the state depicted by the solid line in  FIG. 7 , i.e., the discharge side of the compressor  21  and the gas side of the heat source side heat exchanger  23  are connected, and the intake side of the compressor  21  and the gas side gate valve  28  are connected. In addition, the heat source side expansion valve  26  is in a state wherein its opening is regulated. Furthermore, the gas refrigerant introduction valve  238   a  and the discharge valve  34   c  that constitute the gas separation apparatus  231  are both shut off, and the gas separation apparatus  231  is in an unused state.  
      If the compressor  21  is activated with the refrigerant circuit  510  and the gas separation apparatus  231  in this state, then the gas refrigerant is sucked into and compressed by the compressor  21 , sent to the heat source side heat exchanger  23  via the four-way switching valve  522 , wherein heat is exchanged with the air or the water that serves as the heat source, and condensed. This condensed liquid refrigerant flows through the check valve  524   a  of the bridge circuit  524  and into the receiver  25 . At this point, the heat source side expansion valve  26  connected to the downstream side of the receiver  25  is in a state wherein its opening is regulated, and the refrigerant pressure ranging from the discharge side of the compressor  21  to the heat source side expansion valve  26  of the liquid side refrigerant circuit  511  rises to the condensing pressure of the refrigerant. Namely, the refrigerant pressure inside the receiver  25  rises to the condensing pressure of the refrigerant. Consequently, the noncondensable gas-containing (specifically, sealed gas) refrigerant in a saturated, gas-liquid mixed phase, remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  after releasing the sealed gas, flows into the receiver  25 . Furthermore, the refrigerant that flows into the receiver  25  is gas-liquid separated into liquid refrigerant and noncondensable gas-containing gas refrigerant. Moreover, the gas refrigerant containing the noncondensable gas accumulates in the upper part of the receiver  25 , and the liquid refrigerant temporarily accumulates inside the receiver  25 , subsequently flows out from the lower part of the receiver  25 , and is sent to the heat source side expansion valve  26 . The liquid refrigerant sent to this heat source side expansion valve  26  expands, transitions to a gas-liquid two-phase state, and is sent to the utilization unit  5  via the check valve  524   c  of the bridge circuit  524 , the liquid side gate valve  27 , and the liquid refrigerant connecting pipe  6 . Furthermore, the refrigerant sent to the utilization unit  5  evaporates, after it is heat exchanged with the indoor air by the utilization side heat exchanger  51 . This evaporated gas refrigerant once again is sucked into the compressor  21  via the gas refrigerant connecting pipe  7 , the gas side gate valve  28 , and the four-way switching valve  522 .  
      In this cooling operation state, the operation that discharges the noncondensable gas can be performed the same as the gas separation apparatus  231  of the first embodiment and its modified examples. This procedure is the same as the operation that discharges the noncondensable gas in the gas separation apparatus  231  of the modified example in the first embodiment, and its explanation is therefore omitted.  
      (Case of Discharging Noncondensable Gas While Performing Heating Operation)  
      Next, the case of performing the operation that circulates the refrigerant inside the refrigerant circuit  510  by the heating operation will be explained. At this time, the four-way switching valve  522  is in the state depicted by the broken line in  FIG. 7 , i.e., the discharge side of the compressor  21  and the gas side gate valve  28  are connected, and the intake side of the compressor  21  and the gas side of the heat source side heat exchanger  23  are connected. In addition, the heat source side expansion valve  26  is in a state wherein its opening is regulated. Furthermore, the gas refrigerant introduction valve  238   a  and the discharge valve  34   c  that constitute the gas separation apparatus  231  are both shut off, and the gas separation apparatus  231  is in an unused state.  
      If the compressor  21  is activated with the refrigerant circuit  510  and the gas separation apparatus  231  in this state, then the gas refrigerant is sucked into and compressed by the compressor  21 , sent to the utilization unit  5  via the four-way switching valve  522 , the gas side gate valve  28 , and the gas refrigerant connecting pipe  7 . The refrigerant sent to the utilization unit  5  is condensed after it is heat exchanged with the indoor air by the utilization side heat exchanger  51 . This condensed liquid refrigerant flows through the liquid refrigerant connecting pipe  6 , the liquid side gate valve  27 , the check valve  524   b  of the bridge circuit  524 , and into the receiver  25 . At this point, the heat source side expansion valve  26  connected to the downstream side of the receiver  25  is in a state wherein its opening is regulated, the same as during cooling operation, and the refrigerant pressure ranging from the discharge side of the compressor  21  to the heat source side expansion valve  26  of the liquid side refrigerant circuit  511  rises to the condensing pressure of the refrigerant. Namely, the refrigerant pressure inside the receiver  25  rises to the condensing pressure of the refrigerant. Consequently, the noncondensable gas-containing (specifically, sealed gas) refrigerant in a saturated, gas-liquid mixed phase, remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  after releasing the sealed gas, flows into the receiver  25 , the same as during cooling operation. Furthermore, the refrigerant that flows into the receiver  25  is gas-liquid separated into liquid refrigerant and noncondensable gas-containing gas refrigerant. Moreover, the gas refrigerant containing the noncondensable gas accumulates in the upper part of the receiver  25 , and the liquid refrigerant temporarily accumulates inside the receiver  25 , subsequently flows out from the lower part of the receiver  25 , and is sent to the heat source side expansion valve  26 . The liquid refrigerant sent to this heat source side expansion valve  26  expands, transitions to a gas-liquid two-phase state, and is sent to the heat source side heat exchanger  23  via the check valve  524   d  of the bridge circuit  524 . Furthermore, the refrigerant sent to the heat source side heat exchanger  23  evaporates, after it is heat exchanged with air or water serving as the heat source. This evaporated gas refrigerant once again is sucked into the compressor  21  via the four-way switching valve  522 .  
      In this heating operation state as well, the operation that discharges the noncondensable gas can be performed the same as in the cooling operation state. This procedure is the same as the abovementioned operation that discharges noncondensable gas in the cooling operation state, i.e., the operation that discharges the noncondensable gas in the gas separation apparatus  231  of the modified example in the first embodiment, and its explanation is therefore omitted.  
      Thus, in the air conditioner  501  of the present embodiment, the operation that discharges the noncondensable gas remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  from inside the refrigerant circuit  510  can be performed using the gas separation apparatus  231  by circulating the refrigerant inside the refrigerant circuit  510 , the same as the first embodiment and its modified examples.  
     (3) Modified Example 1  
      With the abovementioned gas separation apparatus  231 , the receiver  25  and the separation membrane apparatus  34  are connected via the gas refrigerant introduction circuit  238 , but may be integrally constituted, as in the gas separation apparatus  31  incorporated in a heat source unit  602  of an air conditioner  601  in the present modified example depicted in  FIG. 8 , the same as the gas separation apparatus  31  in the first embodiment.  
     (4) Another Modified Example  
      In the air conditioners  501 ,  601  comprising the abovementioned gas separation apparatuses  31 ,  231 , a dryer may be connected to the liquid side refrigerant circuit  511  to eliminate moisture remaining in the refrigerant circuit  510 , the same as the air conditioner  101  in the modified example of the first embodiment.  
     Third Embodiment  
      (1) Constitution of the Air Conditioner  
       FIG. 9  is a schematic view of a refrigerant circuit of an air conditioner  1001  as one example of a refrigeration apparatus according to the third embodiment of the present invention. In the present embodiment, the air conditioner  1001  is capable of cooling operation and heating operation, the same as the air conditioner  501  of the second embodiment, and comprises a heat source unit  1002 , the utilization unit  5 , and the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  for connecting the heat source unit  1002  and the utilization unit  5 . Furthermore, excepting a gas separation apparatus  1031  of the present embodiment, the constitution of the air conditioner  1001  is the same as the air conditioner  501  of the second embodiment, and its explanation is therefore omitted.  
      In the present embodiment, the gas separation apparatus  1031  principally comprises a separation membrane apparatus  1034 .  
      The separation membrane apparatus  1034  separates the noncondensable gas from the noncondensable gas-containing gas refrigerant that accumulated in the upper part of the receiver  25 , and discharges the separated noncondensable gas out of the refrigerant circuit  510 , the same as the separation membrane apparatus  34  of the first and second embodiments. The separation membrane apparatus  1034  is connected to the receiver  25  via the gas refrigerant introduction circuit  238 . In the present embodiment, the separation membrane apparatus  1034  comprises, as depicted in  FIG. 10 , an apparatus main body  1034   a , a separation membrane  1034   b  disposed so that it partitions the space inside the apparatus main body  1034   a  into a space S 3  (upstream side) and a space S 4  (downstream side) in communication with the gas refrigerant introduction circuit  238 , a discharge valve  1034   c  connected to the space S 3 , and a gas refrigerant outflow circuit  1041  connected to the space S 4 . In the present embodiment, the separation membrane  1034   b  uses a membrane capable of selectively permeating gas refrigerant from the noncondensable gas-containing gas refrigerant. A nonporous membrane made of polysulfone membrane, silicone rubber membrane, and the like, is used for such a separation membrane. Here, the nonporous membrane is a homogenous membrane that does not have numerous extremely fine pores like a porous membrane, and the gas separates due to the speed differential when permeating the inside of the membrane through the processes of dissolving, diffusing, and de-dissolving; in other words, components having a high boiling point and that are highly soluble in the membrane permeate, while components having a low boiling point and that are poorly soluble in the membrane do not permeate. Here, because the boiling points of the R22 and R134a used as the refrigerant in the air conditioner, and the R32 and the R125 contained in the mixed refrigerants R407c and R410a, are all higher than the boiling points of water vapor, oxygen gas, and nitrogen gas, they can be separated by this nonporous membrane. Thereby, the separation membrane  1034   b  can selectively permeate the gas refrigerant from the noncondensable gas-containing gas refrigerant (specifically, the supply gas, which is a gaseous mixture of the noncondensable gas and the gas refrigerant accumulated in the upper part of the receiver  25 ), thereby causing the gas refrigerant to flow from the space S 3  into the space S 4 . The gas refrigerant outflow circuit  1041  is provided so that the space S 4  of the separation membrane apparatus  1034  and the intake side of the compressor  21  are connected, and comprises a gas refrigerant return valve  1041  a that distributes and shuts off the gas refrigerant that permeates the separation membrane  1034   b  and returns into the refrigerant circuit  510 . Here, the gas refrigerant outflow circuit  1041  is provided so that the gas refrigerant returns to the intake side of the compressor  21 , which has the lowest refrigerant pressure inside the refrigerant circuit  510 , and the pressure differential between the space S 3  and the space S 4  can thereby be increased. The discharge valve  1034   c  can release the noncondensable gas, remaining inside the space S 3 , into the atmosphere by causing the gas refrigerant to permeate the separation membrane  1034   b , and can thereby discharge the noncondensable gas out of the refrigerant circuit  510 .  
      (2) Method of Constructing the Air Conditioner  
      The following explains the method of constructing the air conditioner  1001 . Furthermore, excepting the noncondensable gas discharging step, the procedure is the same as the air conditioner  1  constructing method of the first embodiment, and its explanation is therefore omitted.  
      &lt;Noncondensable Gas Discharging Step&gt; 
      After the sealed gas has been released, the liquid side gate valve  27  and the gas side gate valve  28  of the heat source unit  1002  are opened, creating a state wherein the refrigerant circuit of the utilization unit  5  and the refrigerant circuit of the heat source unit  1002  are connected. Thereby, the refrigerant that was pre-filled in the heat source unit  1002  is supplied to the entire refrigerant circuit  510 . However, if the required refrigerant fill quantity is not met just with the amount of refrigerant pre-filled in the heat source unit  1002 , e.g., if the refrigerant connecting pipes  6 ,  7  are long, then refrigerant can be externally supplemented and then filled as needed. Furthermore, if the heat source unit  1002  is not pre-filled with refrigerant, then the entire amount of the refrigerant needed is externally filled. Thereby, the sealed gas (containing the noncondensable gas remaining in the utilization unit  5  if simultaneously performing the seal test on the utilization unit  5 ), which serves as the noncondensable gas remaining in the refrigerant connecting pipes  6 ,  7  after the sealed gas releasing step, is mixed with the refrigerant inside the refrigerant circuit  510 .  
      In this circuit configuration, operation is performed by activating the compressor  21  and circulating the refrigerant inside the refrigerant circuit  510 .  
      (Case of Discharging Noncondensable Gas While Performing Cooling Operation)  
      First, the case of performing the operation that circulates the refrigerant inside the refrigerant circuit  510  by the cooling operation will be explained. At this time, the four-way switching valve  522  is in the state depicted by the solid line in  FIG. 9 , i.e., the discharge side of the compressor  21  and the gas side of the heat source side heat exchanger  23  are connected, and the intake side of the compressor  21  and the gas side gate valve  28  are connected. In addition, the heat source side expansion valve  26  is in a state wherein its opening is regulated. Furthermore, the gas refrigerant introduction valve  238   a , the gas refrigerant return valve  1041  a, and the discharge valve  1034   c  that constitute the gas separation apparatus  1031  are all shut off, and the gas separation apparatus  1031  is in an unused state.  
      If the compressor  21  is activated with the refrigerant circuit  510  and the gas separation apparatus  1031  in this state, then cooling operation is performed the same as in the second embodiment. Furthermore, the operation of the refrigerant circuit  510  is the same as in the second embodiment, and its explanation is therefore omitted.  
      The following explains the operation of discharging the noncondensable gas from inside the refrigerant circuit  510  using the gas separation apparatus  1031 . First, the gas refrigerant introduction valve  238   a  is opened, and the noncondensable gas-containing gas refrigerant (supply gas) that accumulated in the upper part of the receiver  25  is introduced inside the separation membrane apparatus  1034 . Subsequently, the gas refrigerant return valve  1041  a of the separation membrane apparatus  1034  is opened, and the refrigerant pressure inside the space S 4  of the separation membrane apparatus  1034  reaches a pressure the same as the pressure of the refrigerant flowing on the intake side of the compressor  21 . In so doing, the space S 3  of the separation membrane apparatus  1034  is in communication with the upper part of the receiver  25 , and a pressure differential consequently arises between the space S 3  and the space S 4  that corresponds to the pressure differential between the condensing pressure of the refrigerant and the pressure on the intake side of the compressor  21 . Consequently, this pressure differential forms a propulsive force, and the gas refrigerant contained in the supply gas that accumulated inside the space S 3  permeates the separation membrane  1034   b , flows to the space S 4  side, and returns to the intake side of the compressor  21  through the gas refrigerant return valve  1041   a . However, the noncondensable gas (nonpermeating gas), remaining inside the space S 3  due to the gas refrigerant permeating the separation membrane  1034   b  and flowing to the space S 4  side, is released into the atmosphere by the opening of the discharge valve  1034   c . If this operation is executed for the prescribed time, then the noncondensable gas remaining in the liquid refrigerant connecting pipe  6  and the gas refrigerant connecting pipe  7  is discharged from inside the refrigerant circuit  510 .  
      Furthermore, after the noncondensable gas is discharged from inside the refrigerant circuit  510 , the gas refrigerant introduction valve  238   a , the gas refrigerant return valve  1041   a , and the discharge valve  1034   c  that constitute the gas separation apparatus  1031  are all turned off.  
      (Case of Discharging Noncondensable Gas While Performing Heating Operation)  
      The following explains the case wherein the operation that circulates the refrigerant inside the refrigerant circuit  510  is performed by the heating operation. At this time, the four-way switching valve  522  is in the state depicted by the broken line in  FIG. 9 , i.e., in a state wherein the discharge side of the compressor  21  is connected to the gas side gate valve  28 , and the intake side of the compressor  21  is connected to the gas side of the heat source side heat exchanger  23 . In addition, the heat source side expansion valve  26  is in a state in which its opening is regulated. Furthermore, the gas refrigerant introduction valve  238   a , the gas refrigerant return valve  1041  a, and the discharge valve  1034   c  that constitute the gas separation apparatus  1031  are all shut off, and the gas separation apparatus  1031  is in an unused state.  
      If the compressor  21  is activated with the refrigerant circuit  510  and the gas separation apparatus  1031  in this state, the same heating operation as in the second embodiment is performed. Furthermore, the operation of the refrigerant circuit  510  and the gas separation apparatus  1031  is the same as the operation to discharge the noncondensable gas in the cooling operation state, and its explanation is therefore omitted.  
      (3) Features of the Air Conditioner, and the Constructing Method Thereof  
      The air conditioner  1001  of the present embodiment differs from the constitution of the air conditioners  1 ,  101 ,  201 ,  501 ,  601  of the first and second embodiments in that a nonporous membrane is employed as the separation membrane  1034   b , which constitutes the separation membrane apparatus  1034 , that selectively permeates the refrigerant, but otherwise has the same features as the air conditioners  1 ,  101 ,  201 ,  501 ,  601  and their constructing methods in the first and second embodiments.  
     (4) Modified Example 1  
      The abovementioned gas separation apparatus  1031  is constituted so that the gas refrigerant separated in the separation membrane apparatus  1034  is returned to the intake side of the compressor  21  via the gas refrigerant outflow circuit  1041 , but may be provided so that a gas refrigerant outflow circuit  1141  is connected between the separation membrane apparatus  1034  and the heat source side expansion valve  26  downstream side (specifically, between the downstream side of the heat source side expansion valve  26  and the check valves  524   c ,  524   d  of the bridge circuit  524 ), as in a gas separation apparatus  1131  incorporated in a heat source unit  1102  of an air conditioner  1101  of the present modified example depicted in  FIG. 11 .  
     (5) Modified Example 2  
      With the abovementioned gas separation apparatuses  1031 ,  1131 , the receiver  25  and the separation membrane apparatus  1034  are connected via a gas refrigerant introduction circuit  238 , but the receiver  25  and the separation membrane apparatus  1034  may be constituted integrally, as in a gas separation apparatus  1231  incorporated in a heat source unit  1202  of an air conditioner  1201  of the present modified example depicted in  FIG. 12 , the same as the gas separation apparatus  31  in the first embodiment. At this time, the upper part space (i.e., the space on the upstream side of the separation membrane  34   b ) of the receiver  25  is connected to the discharge valve  1034   c , and the space on the downstream side of the separation membrane  1034   b  is connected to the gas refrigerant outflow circuit  1041 .  
     (6) Another Modified Example  
      In the abovementioned gas separation apparatus  1131 , the receiver  25  and the separation membrane apparatus  1034  may be integrally constituted, as in the gas separation apparatus  1231 .  
      In addition, in the air conditioners  1 ,  101 ,  201 ,  501 ,  601  of the first embodiment and its modified examples, the separation membrane apparatus  1034  of the present embodiment and its modified examples may be employed as the separation membrane apparatus that constitutes the gas separation apparatus.  
      Furthermore, in the air conditioners  1001 ,  1101 ,  1201  comprising the abovementioned gas separation apparatuses  1031 ,  1131 ,  1231 , the dryer for eliminating the moisture remaining in the refrigerant circuit  510  may be connected to the liquid side refrigerant circuit  511 , the same as in the air conditioner  101  in the modified example of the first embodiment.  
     Fourth Embodiment  
      (1) Constitution and Features of the Air Conditioner  
       FIG. 13  is a schematic view of the refrigerant circuit of an air conditioner  1501  as one example of the refrigeration apparatus according to the fourth embodiment of the present invention. The air conditioner  1501  is a so-called multitype air conditioner capable of cooling operation and heating operation, and comprises a heat source unit  1502 , a plurality (in the present embodiment, two units) of utilization units  1505 , and a liquid refrigerant connecting pipe  1506  and a gas refrigerant connecting pipe  1507  that connect the heat source unit  1502  and the plurality of utilization units  1505 .  
      Each utilization unit  1505  principally comprises the utilization side heat exchanger  51  and a utilization side expansion valve  1552 . Here, the utilization side heat exchanger  51  is the same as the utilization side heat exchanger  51  of the air conditioner  501  of the second embodiment, and its explanation is therefore omitted.  
      Each utilization side expansion valve  1552  is connected to the liquid side of the respective utilization side heat exchanger  51  in order to regulate the refrigerant pressure, the refrigerant flow, and the like. In the present embodiment, each utilization side expansion valve  1552  has a function that expands the refrigerant, particularly during cooling operation.  
      The heat source unit  1502  principally comprises the compressor  21 , the four-way switching valve  522 , the heat source side heat exchanger  23 , a bridge circuit  1524 , the receiver  25 , a heat source side expansion valve  1526 , the liquid side gate valve  27 , and the gas side gate valve  28 . Here, the compressor  21 , the four-way switching valve  522 , the heat source side heat exchanger  23 , the receiver  25 , the liquid side gate valve  27 , and the gas side gate valve  28  are the same as the compressor  21 , the four-way switching valve  522 , the heat source side heat exchanger  23 , the receiver  25 , the liquid side gate valve  27 , and the gas side gate valve  28  of the air conditioner  501  of the second embodiment, and their explanations are therefore omitted.  
      In the present embodiment, the bridge circuit  1524  comprises three check valves  524   a - 524   c  and the heat source side expansion valve  1526 , and is connected between the heat source side heat exchanger  23  and the liquid side gate valve  27 . Here, a check valve  524   a  permits only the distribution of the refrigerant from the heat source side heat exchanger  23  to the receiver  25 . A check valve  524   b  permits only the distribution of the refrigerant from the liquid side gate valve  27  to the receiver  25 . A check valve  524   c  permits only the distribution of the refrigerant from the receiver  25  to the liquid side gate valve  27 . The heat source side expansion valve  1526  is connected between the exit of the receiver  25  and the heat source side heat exchanger  23  to regulate the refrigerant pressure, the refrigerant flow, and the like. In the present embodiment, during cooling operation, the heat source side expansion valve  1526  is fully closed and functions so that the refrigerant flowing from the heat source side heat exchanger  23  toward the utilization side heat exchanger  51  flows via the entrance of and into the receiver  25 ; during heating operation, its opening is regulated, and it functions so that the refrigerant flowing from the utilization side heat exchanger  51  (specifically, the exit of the receiver  25 ) toward the heat source side heat exchanger  23  is expanded. Thereby, when the refrigerant flows from the heat source side heat exchanger  23  side toward the utilization side heat exchanger  51  side as during cooling operation, the bridge circuit  1524  functions so that the refrigerant is flowed through the entrance of and into the receiver  25 , and the refrigerant flowing out of the exit of the receiver  25  is distributed to the utilization side heat exchanger  51  side without expanding in the heat source side expansion valve  1526 ; additionally, when the refrigerant flows from the utilization side heat exchanger  51  side toward the heat source side heat exchanger  23  side as during heating operation, the bridge circuit  1524  functions so that the refrigerant flows through the entrance of and into the receiver  25 , and the refrigerant flowing out of the exit of the receiver  25  is distributed to the heat source side heat exchanger  23  side after expanding in the heat source side expansion valve  1526 .  
      The liquid refrigerant connecting pipe  1506  is connected between the liquid side of the utilization side heat exchanger  51  of each of the plurality of utilization units  1505  and the liquid side gate valve  27  of the heat source unit  1502 . The gas refrigerant connecting pipe  1507  is connected between the gas side of the utilization side heat exchanger  51  of each of the plurality of utilization units  1505  and the gas side gate valve  28  of the heat source unit  1502 . The liquid refrigerant connecting pipe  1506  and the gas refrigerant connecting pipe  1507  are the refrigerant connecting pipes constructed on site when newly constructing the air conditioner  1501 , or the refrigerant connecting pipes diverted from an existing air conditioner when replacing any one or both of the heat source unit  1502  and the utilization units  1505 .  
      Here, a liquid side refrigerant circuit  1511  comprises the refrigerant circuit that ranges from the utilization side heat exchanger  51  to the heat source side heat exchanger  23 , including the liquid refrigerant connecting pipe  1506 , the liquid side gate valve  27 , the bridge circuit  1524 , the receiver  25 , and the heat source side expansion valve  1526 . In addition, a gas side refrigerant circuit  1512  comprises the refrigerant circuit ranging from the utilization side heat exchanger  51  to the heat source side heat exchanger  23 , including the gas refrigerant connecting pipe  1507 , the gas side gate valve  28 , the four-way switching valve  522 , and the compressor  21 . In other words, a refrigerant circuit  1510  of the air conditioner  1501  comprises the liquid side refrigerant circuit  1511  and the gas side refrigerant circuit  1512 .  
      The air conditioner  1501  further comprises the gas separation apparatus  231 , which is connected to the liquid side refrigerant circuit  1511 . The gas separation apparatus  231  can separate from the refrigerant and discharge out of the refrigerant circuit  1510  the noncondensable gas, remaining in the liquid refrigerant connecting pipe  1506  and the gas refrigerant connecting pipe  1507 , by operating the compressor  21  and circulating the refrigerant in the refrigerant circuit  1510 , and is built into the heat source unit  1502  in the present embodiment. Here, the gas separation apparatus  231  is the same as the gas separation apparatus  231  of the air conditioner  201  in the modified example of the first embodiment, and its explanation is therefore omitted.  
      In the air conditioner  1501  of this type as well, the operation that discharges the noncondensable gas remaining in the liquid refrigerant connecting pipe  1506  and the gas refrigerant connecting pipe  1507  from inside the refrigerant circuit  1510  can be performed using the gas separation apparatus  231  by using a method of construction the same as the air conditioner  501  of the second embodiment and circulating the refrigerant inside the refrigerant circuit  1510 .  
      In particular, in the case of a multitype air conditioner, as in the air conditioner  1501  of the present embodiment, the length and diameter of each of the refrigerant connecting pipes  1506 ,  1507  is larger than the refrigerant connecting pipes of the comparatively compact air conditioner, as in a room air conditioner, and the amount of noncondensable gas that must be discharged from inside the refrigerant circuit  1510  is large; consequently, this method of construction is useful.  
     (2) Modified Example  
      The receiver  25  and the separation membrane apparatus  34  may be integrally constituted, as in the gas separation apparatus  31  according to the first and second embodiments.  
      In addition, the gas separation apparatuses  1031 ,  1131 ,  1231  each comprising a separation membrane  1034   b  made of a nonporous membrane, according to the third embodiment and its modified examples, may be used as the gas separation apparatus.  
     Another Embodiment  
      The above explained the embodiments of the present invention, referencing the drawings, but the specific constitution is not limited to these embodiments, and it is understood that variations and modifications may be effected without departing from the spirit and scope of the invention.  
      For example, in the abovementioned embodiments, the present invention was applied to an air conditioner capable of operation by switching between cooling and heating operation, an air conditioner dedicated to cooling operation, and a multitype air conditioner with a plurality of utilization units connected thereto; however, the present invention is not limited thereto, and may also be applied to an ice thermal storage type air conditioner, other separate type refrigeration apparatuses, and the like.  
     INDUSTRIAL FIELD OF APPLICATION  
      Using the present invention can improve the efficiency of separating a noncondensable gas with a separation membrane in a refrigeration apparatus constituted, for the purpose of omitting the vacuum drawing work, so that, by using a separation membrane, it can separate and eliminate the noncondensable gas, in a state mixed with a refrigerant inside a refrigerant circuit, that was left inside the refrigerant connecting pipe during on-site construction.