Patent Publication Number: US-2021180843-A1

Title: Receiver/drier for a refrigerant fluid circuit equipping a vehicle, in particular a motor vehicle

Description:
The field of the present invention is that of air conditioning installations equipping vehicles, in particular motor vehicles. The invention more specifically concerns refrigerant fluid receiver/driers equipping a refrigerant fluid circuit that cooperates with an air conditioning installation of this kind. 
     Vehicles, in particular motor vehicles, are routinely equipped with a ventilation, heating and/or climate control installation, also called an air conditioning installation. An air conditioning installation of this kind is in particular dedicated to enhancing the comfort of the passenger compartment of the vehicle. The air conditioning installation cooperates with a closed circuit through which circulates a refrigerant fluid used by a heat exchanger that the air conditioning installation comprises for thermally treating air sent into the passenger compartment. 
     Successively in the direction of circulation of the refrigerant fluid through it, the refrigerant fluid circuit essentially comprises a compressor, a condenser, an expansion member and an evaporator. The refrigerant fluid in the gas phase is compressed by the compressor, transformed into the liquid phase in the condenser, expanded at low pressures by the expansion member and then transformed into the gas phase in the evaporator and routed again to the compressor. 
     In this context, the refrigerant fluid circuit comprises a refrigerant fluid receiver/drier disposed between the condenser and the expansion member. The receiver/drier provides a reserve of refrigerant fluid guaranteeing stable operation of the refrigerant fluid circuit over time. The receiver/drier also houses a particle filter to retain any particles captured by the refrigerant fluid during its circulation through the refrigerant fluid circuit. The receiver/drier further houses a material that absorbs moisture contained in the refrigerant fluid, hereinafter designated the desiccant. 
     The receiver/drier essentially comprises a closed housing accommodating the particle filter and the desiccant. The housing is provided with a fluid inlet for admitting the refrigerant fluid to the interior of the housing and a fluid outlet for evacuating the refrigerant fluid from the housing after it has passed through the desiccant and the particle filter. 
     However, the refrigerant fluid is potentially admitted into the expansion member in a diphasic state between a majority liquid phase and a minority gas phase. 
     The object of the present invention is to improve the admission of the refrigerant fluid in the liquid phase into the expansion member. It more particularly aims to obtain admission of the refrigerant fluid into the expansion member totally in the liquid phase. 
     To this end, the invention consists in a refrigerant fluid receiver/drier that is configured to be placed in a refrigerant fluid circuit and cooperates with an air conditioning installation of a vehicle, in particular a motor vehicle. A receiver/drier of this kind is in particular intended to be disposed between a condenser and an expansion member that the refrigerant fluid circuit comprises. 
     The receiver/drier of the invention is more particularly adapted to have passed through it a refrigerant fluid of a refrigerant fluid circuit for a vehicle, in particular a motor vehicle. The receiver/drier comprises a closed housing provided with a fluid inlet for the admission of the refrigerant fluid to the interior of the housing and a fluid outlet for the evacuation of the refrigerant fluid from the housing. The housing houses at least one desiccant and at least one particle filter. 
     In this context, the receiver/drier of the invention is principally recognizable in that it is provided with a device for separating the refrigerant fluid admitted to the interior of the housing between a liquid phase and a gas phase. 
     Thus according to the invention the receiver/drier is used to house a device for separation of phases of a fluid that is specifically dedicated and adapted to cause a separation of phases of the refrigerant fluid between its liquid phase and its gas phase. The refrigerant fluid evacuated out of the receiver/drier is then totally in the liquid phase for its admission into an expansion member. 
     The receiver/drier is in particular and more particularly configured to be disposed between a condenser and the refrigerant fluid expansion member that the refrigerant fluid circuit comprises, to feed the expansion member with refrigerant fluid in the liquid phase free of moisture. However, a gas phase of the refrigerant fluid may persist despite its cooling in the condenser and be routed to the receiver/drier. 
     The phase separation device then enables an obstacle to be provided against evacuation out of the receiver/drier to the expansion member of a gas phase of the refrigerant fluid admitted into the receiver/drier. 
     In other words, the phase separation device guarantees evacuation of the refrigerant fluid out of the receiver/drier totally in the liquid phase, prior to its admission into the expansion member, even in the case of thermal conditions at the limit for the condensation of the refrigerant fluid. 
     The phase separation device is advantageously arranged as at least one ramp for centrifugal circulation of the refrigerant fluid inside the housing. 
     The ramp is configured to guide the refrigerant fluid and to increase the path that it follows inside the housing, by causing acceleration by centrifugal force of the flow of the refrigerant fluid in the liquid phase inside the housing. The effect of this is to guarantee better separation between the liquid phase and the gas phase of the refrigerant fluid, and finally evacuation of the refrigerant fluid from the receiver/drier totally in the liquid state. 
     The phase separation device is preferably disposed in the housing between the fluid inlet and the desiccant. The phase separation device is more specifically disposed in the housing between on the one hand the fluid inlet and on the other hand the desiccant and the particle filter. 
     According to the direction of circulation of the refrigerant fluid inside the receiver/drier, the desiccant and/or the particle filter are disposed inside the housing downstream of the phase separation device and upstream of a fluid tank. A fluid tank of this kind is in particular dedicated to storing a quantity of refrigerant fluid inside the housing after its passage through the phase separation device. 
     The desiccant is for example packaged in a cartridge housed inside the housing, in particular upstream of the fluid tank in the direction of circulation of the refrigerant fluid inside the receiver/drier. The cartridge may be equipped with at least one particle filter. At least one particle filter may also be provided downstream of the fluid tank in the direction of circulation of the refrigerant fluid inside the receiver/drier. For example, the particle filter may be provided on a dip tube connecting the refrigerant fluid tank to the fluid outlet. 
     According to one embodiment, the phase separation device is configured as at least one helix with multiple turns. Each of the turns produces successively along the axis of the helix a ramp for centrifugal circulation of the refrigerant fluid inside the housing. The refrigerant fluid in the liquid phase is therefore driven successively by each of the turns of the helix from the fluid inlet to the fluid reserve via at least the desiccant and even also the particle filter. 
     The axis of the helix is preferably centred on a longitudinal axis of the housing extending between a first end of the housing provided with the fluid inlet and a bottom of the receiver/drier delimiting a fluid reserve for the storage of a quantity of refrigerant fluid inside the housing. 
     The first end of the housing and the bottom of the receiver/drier are in particular opposite longitudinal ends of the receiver/drier along the longitudinal axis of the housing. In this context, in the operating state of the receiver/drier, the longitudinal axis of the housing, and therefore the axis of the helix, are oriented in the direction of the gravity axis, the first end of the housing then overlying the bottom of the receiver/drier and therefore the tank for storing refrigerant fluid inside the housing. 
     According to one embodiment, the helix is formed by a body attached to the interior of the housing. 
     The body preferably includes, along the axis of the helix, a channel for draining the refrigerant fluid in the liquid state to the bottom of the receiver/drier. 
     The liquid phase of the refrigerant fluid can thus be driven toward the drainage channel successively by each of the turns of the helix composing its wall. The drainage channel can define only one or of a plurality of passes of the refrigerant fluid through the body. 
     According to one embodiment, the body is advantageously formed by rolling and drawing a metal sheet to confer on it its helix configuration. The body can therefore be obtained at lower cost and easily installed inside the housing, in particular by threading the body into the interior of the housing from one of its longitudinal ends. 
     According to a variant, the body can be machined at its periphery to form the helix and to form the drainage channel in a central zone of the body extending along the axis of the helix. 
     The body is preferably pressed against the interior face of the wall of the housing extending between its longitudinal ends. The wall of the housing then forms a member for confinement of the refrigerant fluid flowing along the turns of the helix and then forcing its evacuation to the drainage channel. 
     According to one embodiment, the helix is formed in the wall of the housing. 
     The helix is for example formed by machining the internal face of the wall of the housing. The turns composing the helix preferably discharge into a central opening of the housing that extends between the inlet mouth and at least the desiccant and/or the particle filter, or preferably even as far as the fluid reserve. 
     The empty space of the housing then advantageously forms a chamber for draining the refrigerant fluid in the liquid phase to the fluid reserve via the desiccant and/or the particle filter. The empty space preferably also forms a space for receiving the desiccant and/or the particle filter that extends toward the fluid reserve in line with the drainage chamber. 
     According to one embodiment, at least one cap of the housing is provided with the fluid inlet and/or the fluid outlet. 
     For example, a first cap provided at least with the fluid inlet is a cap for closing said first end of the housing. A second cap providing the fluid reserve forms the bottom of the receiver/drier by closing a second end of the housing longitudinally opposite its first end. 
     The second cap can be provided with the fluid outlet. In this case, at least one particle filter is disposed between the phase separation device and the fluid reserve. Two particle filters are preferably disposed on respective opposite sides of the desiccant along the longitudinal axis of the housing. 
     According to a variant, the first cap is also provided with the fluid outlet, which is connected to a first end of a dip tube the second end of which discharges into the fluid reserve provided by the second cap. 
     In this case, the dip tube can be equipped with the particle filter, which is in particular attached to and/or integral with the second end of the dip tube. 
     According to one embodiment, the at least one cap is removably mounted on the housing, preferably with a seal, to allow access to the interior of the housing. Access to the interior volume of the housing is in particular provided to enable maintenance of the receiver/drier. One such maintenance operation is in particular an operation to replace the desiccant when it is saturated with moisture and/or an operation to clean and/or replace the particle filter. 
     According to a variant, the receiver/drier is preferably a consumable product replaced in the event of a malfunction by another receiver/drier, such as in particular in the event of saturation of the desiccant with moisture and/or at the end of a predefined service life of the receiver/drier. 
     For example, the housing is sealed by being formed of a peripheral wall oriented along the longitudinal axis of the housing. The outlets to the exterior of the peripheral wall are then closed by the caps, at least one of which is sealed to and/or integral with the housing. 
     The peripheral wall of the housing is for example formed by rolling a metal sheet and by welding its edges along the longitudinal axis of the housing. Again, for example, the peripheral wall of the housing is formed by extrusion. Again, for example, the peripheral wall of the housing is formed by drawing a metal sheet along the longitudinal axis of the housing, either of the caps then being integrated with the peripheral wall of the housing by the shaping of the sheet. 
     The caps can be made of plastic material and/or metal. The caps can be manufactured by moulding and/or by machining. 
     The invention moreover covers a heat exchanger for a refrigerant fluid circuit, recognizable in that it comprises a receiver/drier as described in the present document. A heat exchanger of this kind can be used as a condenser in a refrigerant fluid circuit. 
     According to one embodiment of the heat exchanger, the receiver/drier is integral with the condenser between two passes of the refrigerant fluid through the condenser. In this case the condenser more particularly includes a path for circulation of the refrigerant fluid through it subdivided into at least two passes between which is disposed a circulation path specific to the receiver/drier. The refrigerant fluid admitted in the gas phase to the interior of the condenser circulates in a first pass to cool it, which causes a partial change of phase of the refrigerant fluid to its liquid phase. 
     The refrigerant fluid then circulates inside the receiver/drier prior to its second pass through the condenser, the effect of which is to direct the refrigerant fluid strictly in the liquid phase to the second pass. The second pass of the refrigerant fluid then enables completion of the cooling of the refrigerant fluid, at this time only in the liquid phase, prior to its admission to the expansion member. 
     This improves the performance of the condenser because of the cooling of the refrigerant fluid inside the condenser in two stages and because of its admission into the second pass in the strictly liquid state. 
     The invention also consists in a refrigerant fluid circuit of a vehicle, in particular a motor vehicle. The refrigerant fluid circuit of the invention is principally recognizable in that it comprises a receiver/drier according to the invention disposed between a condenser and an expansion member that the refrigerant fluid circuit comprises. 
     According to one embodiment, the receiver/drier is installed on a conduit of the refrigerant fluid circuit connecting an opening for evacuation of the refrigerant fluid from the condenser and a mouth for admission of the refrigerant fluid into the expansion member. 
    
    
     
       Other features, details and advantages of the invention will emerge more clearly on reading the description given hereinafter by way of illustrative example with reference to the figures of the appended drawings in which: 
         FIG. 1  is a diagram of a refrigerant fluid circuit illustrating the context of the invention, 
         FIG. 2  and  FIG. 3  are perspective views of a receiver/drier in accordance with a first embodiment of the invention, respectively in an exploded view and when assembled, 
         FIG. 4  and  FIG. 5  are views in axial section of a receiver/drier in accordance with a second embodiment of the invention, respectively in an exploded view and when assembled. 
     
    
    
     It must first be noted that the figures disclose the invention in detail for the purposes of execution of the invention. Said figures and their detailed descriptions can of course if necessary serve to define the invention better. 
     In  FIG. 1 , a refrigerant fluid FR circuit  1  is configured to equip a vehicle, in particular a motor vehicle. The circuit  1  is a closed circuit in which the refrigerant fluid FR circulates and is subjected to successive changes of phase between a gas phase and a liquid phase when it travels around the circuit  1 . A circuit  1  of this kind is in particular used for an air conditioning installation dedicated to improving the comfort of the passenger compartment of the vehicle. 
     In the embodiment shown, the circuit  1  essentially comprises, successively in the direction S 1  of circulation of the refrigerant fluid FR around the circuit  1 , a compressor  2 , a condenser  3  or gas cooler, an expansion member  4 , in particular a thermostatic expansion valve, and at least one heat exchanger  5 . 
     The heat exchanger  5  is in particular an equipment unit of the air conditioning installation configured as a heat exchanger and/or an evaporator. The heat exchanger  5  is dedicated to the heat treatment of a flow of air through it, before the flow of air is sent to the passenger compartment of the vehicle by the air conditioning installation. 
     A receiver/drier  6  of the refrigerant fluid FR is placed on the circuit  1  between the condenser  3  and the expansion member  4 . The receiver/drier  6  provides a reserve of refrigerant fluid FR and desiccation and/or filtering of the refrigerant fluid FR circulating inside the circuit  1 . 
     In the example shown, the receiver/drier  6  is integrated into the condenser  3  and disposed between two passes Pa 1 , Pa 2  of the refrigerant fluid FR inside the condenser  3 . 
     A first pass Pal cools the refrigerant fluid FR before it is admitted to the interior of the receiver/drier  6 . The refrigerant fluid FR then flows inside the dehydrating cylinder  6  and is then evacuated to the second pass Pa 2 . The refrigerant fluid FR is then cooled again as it circulates through the second pass Pa 2 , and is then sent to expansion member  4 . 
     According to a variant, the receiver/drier  6  can also be placed on a pipe  7  of the circuit  1  connecting an opening  8  for evacuation of the refrigerant fluid FR out of the condenser  3  and an opening  9  for admission of the refrigerant fluid FR into the expansion member  4 . 
     The example of a minimal architecture of the circuit  1  shown in  FIG. 1  is given by way of illustration and is not restricting on the scope of the invention, given the various potential architectures of the circuit  1 . 
     In  FIGS. 2 to 4 , a receiver/drier  6  according to the invention comprises a housing  10  extending along a longitudinal axis A 1 . The housing  10  in particular comprises a circular wall  11  around the longitudinal axis A 1 . The longitudinal ends  10   a,    10   b  of the housing  10  are open to the exterior of the housing  10  and are closed by caps  12   a,    12   b  that are attached to and/or integral with the housing  10 , for example by cementing them together. 
     In the situation in particular where the caps are removably attached to the housing, at least one seal  13   a,    13   b  preferably surrounds conjointly the wall  11  of the housing  10  and at least one of the caps  12   a,    12   b  where they are cemented together, as shown for example in  FIGS. 3 and 4 . 
     At least one of the caps  12   a,    12   b  is provided with a fluid inlet  14  for the admission of the refrigerant fluid FR to the interior of the housing  10  and/or a fluid outlet  15  for the evacuation of the refrigerant fluid FR from the housing  10 . 
     The housing  10  houses a cartridge  16  of desiccant, in other words a desiccating material having the property of absorbing moisture, and at least one particle filter  17   a,    17   b,    17   c.  The desiccant  16  makes it possible to capture moisture and the particle filter or filters  17   a,    17   b,    17   c  make(s) it possible to retain the impurities that the refrigerant fluid FR is liable to contain following its circulation through the circuit  1 . 
     The refrigerant fluid FR admitted to the interior of the housing  10  following its at least partial passage through the condenser  3  is in the diphasic state between a mainly liquid phase and a gas phase. 
     In this context, the receiver/drier  6  is equipped with a phase separation device  18  between a liquid phase and a gas phase of the refrigerant fluid FR, resulting in evacuation of the refrigerant fluid FR from the housing  10  totally in the liquid phase. 
     In the embodiments shown, the phase separation device  18  more particularly forms at least one ramp  19  for centrifugal circulation of the refrigerant fluid FR inside the housing  10 , from the fluid inlet  14  to a bottom  20  of the receiver/drier  6 . The ramp or ramps  19  in particular extend(s) in the direction of the bottom  20  of the receiver/drier  6  around a longitudinal axis A 1  with an inclination relative to the longitudinal axis A 1 . A single continuous ramp  19  can be formed in the phase separation device  18 . 
     The ramp  19  delimits inside the housing  10  a guide channel  21  for the refrigerant fluid FR, forming a spiral for driving the refrigerant fluid FR by centrifugal force from the fluid inlet  14  to the bottom  20  of the receiver/drier  6 . 
     The fluid inlet  14  is in particular provided via a first cap  12   a  disposed vertically in line with the bottom  20  of the receiver/drier  6  in the operating state of the receiver/drier  6  as shown in the figures. 
     The concept of vertical alignment is therefore relative to the operating state of the receiver/drier  6 , in which the longitudinal axis A 1  is oriented along the gravity axis so that the refrigerant fluid FR flows along the phase separation device  18  vertically in line with a fluid reserve  22  dedicated to the storage of a quantity of refrigerant fluid FR inside the receiver/drier  6 . The bottom  20  of the receiver/drier  6  is provided by a second cap  12   b  for closing the housing  10  that delimits at least partially the fluid reserve  22 . 
     In the embodiments shown, the ramp  19  is formed by the turns of a helix  23  arranged inside the housing  10 . The helix  23  and the housing  10  are coaxial, the axis A 2  of the helix  23  and the longitudinal axis A 1  preferably coinciding. The channel  21  is delimited between the turns of the helix  23  and the interior face  24  of the wall  11  of the housing  10 . 
     The ramp or ramps  19  formed by the turns of the helix  23  preferably extend(s) between the fluid inlet  14  and the desiccant cartridge  16  and/or also preferably the particle filter or filters  17   a,    17   b,    17   c  in the direction S 2  of circulation of the refrigerant fluid FR inside the housing  10 . 
     An axial median opening  25   a,    25   b  through the helix  23  enables draining of the refrigerant fluid FR in the liquid phase, which circulates successively inside the channel  21  toward the bottom  20  of the receiver/drier  6 , and to be more specific toward the desiccant cartridge  16 . There is therefore obtained inside the housing  10  a separation of phases of the refrigerant fluid FR between its liquid phase and its gas phase, before its evacuation from the housing  10  via the fluid outlet  15 . 
     In the example shown in  FIGS. 2 and 3 , the housing  10  is formed by drawing a metal sheet along the longitudinal axis A 1 , the first cap  12   a  being integral with the housing  10  by being produced from the metal sheet during the drawing operation. The second cap  12   b  is cemented to the housing  10  by and provided with the fluid outlet  15 , the first cap  12   a  being provided with the fluid inlet  14 . 
     The housing  10  houses the desiccant cartridge  16  and the two particle filters  17   a,    17   b,  which are disk shaped. The particle filters  17   a,    17   b  are disposed on either side of the desiccant cartridge  16  along the longitudinal axis A 1 . The particle filters  17   a,    17   b  are potentially housed inside the desiccant cartridge  16 . 
     The phase separation device  18  is formed of a body  26  produced from a rolled and drawn metal sheet conferring on it its helix  23  configuration. The body  26  is attached to the interior of the housing  10  by being fixed, for example cemented, in position on its wall  11  between the first cap  12   a  and the desiccant cartridge  16 . 
     The turns of the helix  23  are configured as funnels encouraging the flow of the refrigerant fluid FR in the liquid phase toward the opening referred to above, the latter here taking the form of a drainage channel  25   a  for the refrigerant fluid FR, into which each of the turns of the helix  23  discharges. The drainage channel  25   a  is formed in the axial zone of the body  26  and extends along the longitudinal axis A 1 . 
     In the example shown, the fluid inlet  14  is provided by a fluid inlet tube  14   a  passing through the wall  11  of the housing  10  with an orientation T 1  transverse to its longitudinal axis A 1 . As can be seen in  FIG. 3 , the wall of the inlet tube  14   a  includes an opening  14   b  disposed near the wall  11  of the housing, which produces a fluid passage oriented along the longitudinal axis A 1  to guide the refrigerant fluid FR to the helix  23 . The second cap  12   b  includes an orifice  27  for admission of the refrigerant fluid FR to the fluid reserve  22  delimited by the second cap  17   b,  which in the embodiment shown includes the fluid outlet  15  oriented along the longitudinal axis A 1 . 
     Thus, as shown in  FIG. 3 , the refrigerant fluid FR is admitted to the interior of the housing  10  via the inlet tube  14   a  transversely to the longitudinal axis A 1 , and is then guided by the inlet tube  14   a  toward the opening  14   b  and therefore toward the helix  23 . The refrigerant fluid FR then circulates along the helix  23  and is progressively directed in the liquid phase toward the drainage channel  25   a,  which discharges vertically in line with the desiccant cartridge  16 . 
     The refrigerant fluid FR then passes through the desiccant cartridge  16  and the particle filters  17   a,    17   b,  is then admitted into the fluid reserve  22  via the admission orifice  27  and is then evacuated from the housing  10  through the fluid outlet  15 . 
     In the embodiment shown in  FIGS. 4 and 5 , the wall  11  of the housing  10  is formed for example by moulding or by rolling a metal sheet and closing it on itself by welding together its longitudinal edges. Each of the caps  12   a,    12   b  is formed of attached elements that are fixed to the housing, at least one of the gaps  12   a,    12   b  being cemented to the housing  10  and/or removably attached to the housing  10 . 
     The fluid inlet  14  is produced through the first cap  12   a,  for example being formed by drilling the first cap  12   a.  The fluid inlet  14  includes a first section  14   c  oriented along the longitudinal axis A 1 , the first section  14   c  being extended by a second section  14   d  that extends with an orientation T 1  transverse to the longitudinal axis A 1  and discharges toward the helix  23 . 
     The fluid outlet  15  is produced through the first cap  12   a  and oriented along the longitudinal axis A 1 . The fluid outlet  15  is connected to the fluid reserve  23  by a dip tube  28  that is preferably provided with a particle filter  17   c.    
     The base separation device  18  is integral with the wall  11  of the housing  10 , the helix  23  being formed in the material of the wall  11  of the housing  10 . The helix  23  can be formed during the moulding of the housing  10  and/or by machining the wall  11  of the housing  10 . Each of the channels  21  formed by the turns of the helix  23  then discharges into the opening of the housing  10  referred to above, which here produces a chamber  25   b  for draining the liquid phase refrigerant fluid FR to the fluid reserve  22 . 
     Downstream of the drainage chamber  25   b  in the direction S 2  of circulation of the refrigerant fluid FR inside the housing  10 , the axial opening of the housing  10  produces a space  25   c  to receive the desiccant cartridge  16  and extends the drainage chamber  25   b  toward the fluid reserve  22 . 
     Thus as shown in  FIG. 5 , the refrigerant fluid FR is admitted to the interior of the housing  10  along the longitudinal axis A 1  via the first section  14   c  of the fluid inlet  14 , and is then directed transversely toward the helix  23 . The refrigerant fluid FR then circulates along the helix  23 , being progressively directed in the liquid phase toward the drainage chamber  25   b  which conveys the refrigerant fluid FR to the desiccant cartridge  16 . The refrigerant fluid FR then passes through the desiccant cartridge  16 , is then admitted into the fluid reserve  22 , and is then evacuated from the housing  10  via the dip tube  28 . 
     It is to be noted in the various examples shown that the fluid inlet  14  and/or the fluid outlet  15  can be individually oriented essentially along the longitudinal axis A 1  and/or transversely T 1  to the longitudinal axis A 1 . In one example, the inlet tube  14   a  can be positioned tangentially to the interior phase  24  of the wall  11  of the housing  10 . A disposition of this kind makes it possible to encourage the commencement of centrifugal circulation of the refrigerant fluid on entering the ramp. Generally speaking, the fluid inlet  14  and the fluid outlet  15  can be oriented in any direction relative to the longitudinal axis Al discharging toward the helix  23 . 
     Thus the ways of connecting the receiver/drier  6  to the circuit  1  and/or to the condenser  3  can be organized freely, without affecting the separation of phases of the refrigerant fluid FR between its liquid phase and its gas phase produced by the phase separation device  18 , and therefore without affecting the obtaining of evacuation from the receiver/drier  6  of the refrigerant fluid FR completely in the liquid phase.