Abstract:
A seal configured for use in a chiller refrigeration system is provided including a first flange and a second flange. The first flange and the second flange are coaxially aligned and in direct contact. The second flange includes at least one groove within which a first sealing mechanism and a second sealing mechanism are positioned. The first sealing mechanism and the second sealing mechanism are separated by a distance such that a chamber configured to receive a pressurized gas is formed between the first and second sealing mechanisms.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates generally to chiller refrigeration systems and, more particularly, to a seal that prevents ambient air from entering an interface of a chiller refrigeration system. 
     Water cooled centrifugal chillers commonly use low and medium pressure refrigerants; however, low pressure refrigerants have a higher cycle efficiency than medium pressure refrigerants. Because the saturation pressure is lower than the ambient pressure during normal operation, air will leak into the cooler and ultimately travel to the condenser. Air is non-condensable, so the air stays in the condenses and raises the pressure above the saturation vapor pressure, thus causing the compressor to work harder, thereby offsetting the benefit associated with using a low pressure refrigerant. Low pressure chillers typically include a purge system used periodically to remove non-condensables which adds both complexity and cost to the chiller. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to an aspect of the invention, a seal configured for use in a chiller refrigeration system is provided including a first flange and a second flange. The first flange and the second flange are coaxially aligned and in direct contact. The second flange includes at least one groove within which a first sealing mechanism and a second sealing mechanism are positioned. The first sealing mechanism and the second sealing mechanism are separated by a distance such that a chamber configured to receive a pressurized gas is formed between the first and second sealing mechanisms. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic illustration of an exemplary chiller refrigeration system; 
         FIG. 2  is a perspective view of an exemplary chiller refrigeration system; 
         FIG. 3  is a cross-sectional view of a seal arranged at an interface between components of the chiller refrigeration system according to an embodiment of the invention; and 
         FIG. 4  is a cross-sectional view of a seal arranged at an interface between components of the chiller refrigeration system according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1 and 2 , the illustrated exemplary chiller refrigeration system  10  includes a compressor assembly  30 , a condenser  12 , and a cooler or evaporator  20  fluidly coupled to form a circuit. A first conduit  11  extends from adjacent the outlet  22  of the cooler  20  to the inlet  32  of the compressor assembly  30 . The outlet  34  of the compressor assembly  30  is coupled by a conduit  13  to an inlet  14  of the condenser  12 . In one embodiment, the condenser  12  includes a first chamber  17 , and a second chamber  18  accessible only from the interior of the first chamber  17 . A float valve  19  within the second chamber  18  is connected to an inlet  24  of the cooler  20  by another conduit  15 . Depending on the size of the chiller system  10 , the compressor assembly  30  may include a rotary, screw, or reciprocating compressor for small systems, or a screw compressor or centrifugal compressor for larger systems. A typical compressor assembly  30  includes a housing  36  having a motor  40  at one end and a centrifugal compressor  44  at a second, opposite end, with the two being connected by a transmission assembly  42 . The compressor  44  includes an impeller  46  for accelerating the refrigerant vapor to a high velocity, a diffuser  48  for decelerating the refrigerant to a low velocity while converting kinetic energy to pressure energy, and a discharge plenum (not shown) in the form of a volute or collector to collect the discharge vapor for subsequent flow to a condenser. Positioned near the inlet  32  of the compressor  30  is an inlet guide vane assembly  60 . Because a fluid flowing from the cooler  20  to the compressor  44  must first pass through the inlet guide vane assembly  60  before entering the impeller  46 , the inlet guide vane assembly  60  may be used to control the fluid flow into the compressor  44 . 
     The refrigeration cycle within the chiller refrigeration system  10  may be described as follows. The compressor  44  receives a refrigerant vapor from the evaporator/cooler  20  and compresses it to a higher temperature and pressure, with the relatively hot vapor then passing into the first chamber  17  of the condenser  12  where it is cooled and condensed to a liquid state by a heat exchange relationship with a cooling medium, such as water or air for example. Because the second chamber  18  has a lower pressure than the first chamber  17 , a portion of the liquid refrigerant flashes to vapor, thereby cooling the remaining liquid. The refrigerant vapor within the second chamber  18  is re-condensed by the cool heat exchange medium. The refrigerant liquid then drains into the second chamber  18  located between the first chamber  17  and the cooler  20 . The float valve  19  forms a seal to prevent vapor from the second chamber  18  from entering the cooler  20 . As the liquid refrigerant passes through the float valve  19 , the refrigerant is expanded to a low temperature two phase liquid/vapor state as it passed into the cooler  20 . The cooler  20  is a heat exchanger which allows heat energy to migrate from a heat exchange medium, such as water for example, to the refrigerant gas. When the gas returns to the compressor  44 , the refrigerant is at both the temperature and the pressure at which the refrigeration cycle began. 
     As a result of the low pressure of the refrigerant within the chiller refrigeration system  10 , outside air is prone to leak into the system  10  at any of a plurality of interfaces between coupled components of the system  10 , such as between fluid conduits and components for example. Exemplary interfaces within the chiller refrigeration system  10  where the pressure of the refrigerant is lower than the ambient air, include, but are not limited to, between the fluid conduit  11  and the suction housing or inlet  32  of the compressor  30 , and between the fluid conduit  15  and the inlet  24  of the cooler  20  for example. Referring now to  FIGS. 3 and 4 , a seal  70  is positioned at an interface between coupled components of the chiller refrigeration system  10  where the pressure of the refrigerant is less than the pressure of the ambient air. The seal  70  includes a first flange  72  integrally formed with a first component of the chiller refrigeration system  10  and a second flange  74  integrally formed with a second component of the chiller refrigeration system  10 . The first flange  72  and the second flange  74  are substantially aligned about a central axis A and are positioned directly adjacent one another. The flanges  72 ,  74  are connected to one another, such as with a plurality of fasteners  76  arranged about the outer periphery of the flanges  72 ,  74  for example. 
     In the non-limiting embodiment illustrated in  FIG. 3 , a first groove  82  is formed in the surface  80  of the second flange  74  facing the first flange  72 , generally near the inner diameter ID of the second flange  74 . The depth of the first groove  82  extends over only a portion of the thickness of the second flange  74 . A second groove  84  having a size and shape similar to the first groove  82  may be formed in the surface  80  of the second flange  74 , near an outer diameter OD thereof. The thickness of a portion  86  of the second flange  74  extending between the first groove  72  and the second groove  84  may be reduced such that an internal chamber  88  is formed between the portion  86  of the second flange  74  and the adjacent surface  78  of the first flange  72 . 
     A pipe or tube  90  extends through a hole (not shown) in portion  86  of the second flange  74  to the chamber  88  formed between portion  86  and the first flange  72 . The tube  90  is configured to supply a highly pressurized gas, such as discharge gas from the condenser  12  of the chiller refrigeration system  10  for example, into the chamber  88 . A first sealing mechanism  92  and a second sealing mechanism  94  are arranged within the first groove  82  and the second groove  84 , respectively, and are configured to seal the chamber  88 . The first sealing mechanism  92  is configured to prevent air from passing between the first and second flanges  72 ,  74  into the chiller refrigeration system  10 . The second sealing mechanism  94  is configured to prevent the hot, high pressure gas from leaking to the low pressure side of the flanges  72 ,  74 . In one embodiment, the sealing mechanisms  92 ,  94  are O-rings formed from a material suitable for use with a refrigerant. 
     In another embodiment, illustrated in  FIG. 4 , the first groove  82  and the second groove  84  are integrally formed as a single groove  85 . In such embodiments, the first sealing mechanism  92  is arranged within the groove  85  near the inner diameter ID of the second flange  74  and the second sealing mechanism  94  is arranged within the groove  85  near the outer diameter OD of the second flange  74 . The chamber  88  is the portion of the groove  85  arranged between the first and second sealing mechanisms  92 ,  94 . 
     By supplying a pressurized gas into the substantially sealed chamber between flanges at an interface in the chiller refrigeration system  10 , ambient air is blocked from leaking through the interface into the system  10 . As a result, the efficiency of the chiller refrigeration is improved. Because the seal reduces the amount of non-condensable air within the system  10 , the purge system used to periodically remove such non-condensables may be substantially reduced or eliminated. The reduction in size and/or capacity of the purge system will result in a cost savings and a simplified chiller refrigeration system  10  design. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. 
     Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.