Abstract:
A conduit has a first end and interior and exterior surfaces extending downstream from the first end. A strainer has a first end and a second end. An upstream portion of the strainer is positioned engaging a projection on the interior surface of the conduit to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. The apparatus may be used as a strainer/coupler and may be used to filter water in a chiller apparatus.

Description:
BACKGROUND OF THE INVENTION 
   (1) Field of the Invention 
   This invention relates to fluid handling, and more particularly to the straining of aqueous heat transfer fluids in refrigeration systems. 
   (2) Description of the Related Art 
   Industrial refrigeration is a well developed field. Many systems involve transferring heat to or from an aqueous solution, often essentially water. The heat may be exchanged with a refrigerant passing along in a closed-loop refrigeration cycle. In many systems, the cooled fluid is water which may flow in a closed loop (e.g., for building or industrial cooling) or in an open loop (e.g., for consumption). In water-cooled chillers, the heated fluid is also water. It is advantageous to strain the fluid to prevent clogging of or damage to system components. 
   BRIEF SUMMARY OF THE INVENTION 
   One aspect of the invention is an apparatus having a conduit and a strainer. The conduit has a first end, interior and exterior surfaces extending downstream from the first end, and a projection on the interior surface. The strainer has a first end and a second end. An upstream portion of the strainer is positioned to engage the conduit projection to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. 
   The apparatus may be used as a coupler for connecting first and second fluid conducting members and extending along an axis between the first end and a second end. The exterior surface proximate the conduit first and second ends may be adapted for connection to the first and second fluid conducting members. Such adaptation may comprise first and second recesses at first and second locations relatively close to the first end and to the second end, respectively. The apparatus may further include first and second clamps for respectively securing the conduit to the first and second fluid conducting members. The first recess may be axially aligned with the projection such as being commonly formed by an annular indentation from the exterior. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view of a chiller system. 
       FIG. 2  is a partial longitudinal sectional view of a strainer/coupler assembly of the system of FIG.  1 . 
       FIG. 3  is an end view of the strainer/coupler assembly of FIG.  2 . 
       FIG. 4  is a detailed longitudinal sectional view of an upstream end portion the strainer/coupler assembly of FIG.  2 . 
       FIG. 5  is a partial longitudinal sectional view of an alternate strainer/coupler assembly. 
   

   Like reference numbers and designations in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
     FIG. 1  shows a chiller system  20 . The system includes two heat exchangers: an evaporator (cooler)  21 ; and a condenser  22 . A first flow from a condenser pump  24  passes through the condenser  22  and a second flow from a cooler pump  26  passes through the cooler  21 . 
   The exemplary system is a water-cooled system in which a refrigeration subsystem  30  has a refrigerant flow path that transfers heat to the first flow in the condenser and draws heat from the second flow in the evaporator. The condenser and cooler pump  24  and  26  respectively have outlet conduit assemblies  50  and  52  connecting such pumps to the heat exchanger and inlet conduit assemblies  54  and  56  receiving water from an outside condensing water loop and a chilled water loop (building or industrial process return). 
   In a exemplary use, the evaporator produces chilled water that may be used, for example, for air conditioning a building or cooling an industrial process. The condenser  22  is coupled to an appropriate external heat rejection system (not shown). Exemplary heat rejection systems may be an open loop cooling tower or a closed loop air-cooled liquid cooler. 
   To protect the pumps from damage and the heat exchanger from clogging, strainers are advantageously provided in both the condenser and cooler flow path loops. In the exemplary embodiment, both inlet conduit assemblies  54  and  56  have an inventive strainer/coupler assembly  60  joining upstream and downstream conduit sections  62  and  64 . Each assembly  60  includes a sleeve  66  and upstream and downstream clamps  68  and  70  coupling the sleeve to the upstream and downstream conduits  62  and  64 . In the exemplary embodiment, the conduits  62  and  64  and sleeve  66  are formed of steel pipestock with rolled clamp grooves (described below) near their ends. 
     FIG. 2  shows further details of the strainer/coupler  60 . The sleeve  66  extends from an upstream end  80  to a downstream end  82  and has a central longitudinal axis  500 . An exemplary sleeve length is 10 cm. The sleeve has inner (interior) and outer (exterior) surfaces  84  and  86 . The upstream and downstream rolled clamp grooves  88  and  90  each define an annular recess  92  having a substantially rectangular cross section in the exterior surface and a rib or annular projection  94  in the interior surface opposite the annular recess. 
   Each exemplary clamp  68  and  70  has a split body, the two halves  100  and  102  ( FIG. 3 ) of which are secured to each other via a pair of diametrically opposite threaded bolt/nut assemblies  104 . An exemplary clamp body is formed of steel and has a pair of radially inwardly-projecting upstream and downstream lips  110  and  112  (FIG.  2 ). The upstream lip of the downstream clamp  70  is compressively engaged to the sleeve in the recess  92  of the downstream groove  90 . The downstream lip of the downstream clamp  70  is similarly compressively engaged to an upstream recess in the downstream conduit  64  of FIG.  1 . Similarly, the downstream lip of the upstream clamp  68  is compressively engaged to the sleeve in the recess of the upstream groove and the upstream lip of the upstream clamp is compressively engaged to a similar recess in the upstream conduit  62  of FIG.  1 . Each clamp body carries an elastomeric gasket  120  ( FIG. 2 ) for providing a seal between the sleeve and adjacent the conduit. 
   The strainer/coupler assembly  60  further includes a strainer  140 . The exemplary strainer  140  comprises a foraminate element  142  having an upstream interior and a downstream exterior. The exemplary foraminate member is formed as a wire mesh (e.g., of 0.5 mm stainless steel wire in a 15 mesh). The exemplary mesh is rolled into a generally frustoconical configuration and welded along a seam  144  ( FIG. 3 ) to extend from a rim at an upstream end  146  of the element to a downstream end  148 . Other forming techniques and other foraminate materials (e.g., perforated members, molded foraminate members, etc.) may be used. An upstream end portion of the foraminate member  142  is secured to a ring  150  captured within the sleeve upstream of the groove  88 . In the exemplary embodiment, the ring  150  is formed of sheet metal (e.g., a stainless steel strip 14 mm wide and 1 mm thick) having an interior surface  152  and an exterior surface  154  and upstream and downstream ends or rims  156  and  158 , respectively. The downstream rim  158  abuts an upstream-facing end of the rib  94  to prevent downstream movement of the ring and thus the strainer element. In the exemplary embodiment, the foraminate member  142  is secured to the ring such as by welding an exterior portion of the foraminate member adjacent the upstream end  146  to the interior surface  152  of the ring. 
   For installation of the strainer, the strainer may be inserted into the sleeve through the upstream end thereof until the ring  150  seats upstream of the groove  88 . In this installed condition, the ring upstream end  156  and foraminate element downstream end  148  define respective upstream and downstream ends of the strainer  140 . The length of the foraminate element downstream of the portion secured to the ring is advantageously chosen to provide sufficient straining surface area. In the exemplary embodiment, the downstream end  148  of the foraminate element is located longitudinally between the downstream groove  90  and sleeve downstream end  82 . Advantageously, the downstream end  148  is located downstream of the upstream groove  88  and, more advantageously, downstream of a midpoint of the sleeve so as to provide a desired amount of surface area. Advantageously, the downstream end  148  remains upstream of the sleeve downstream end  82  so that the recessing of the strainer may protect the strainer from damage during assembly or disassembly of the inlet conduit assemblies. 
   For installation of the strainer/coupler, the sleeve is then placed between the adjacent conduits and the clamps are put in place and their bolts/nuts tightened to secure and seal the sleeve ends to the respective conduits. Disassembly for perodic cleaning of the strainer at a cleaning interval or replacement at a replacement interval or as may otherwise be required is by a reverse of this process. 
     FIG. 5  shows an alternate strainer/coupler assembly  200  having a sleeve  202  and a strainer  204  which, except as described below, may be similar to the sleeve  66  and strainer  140  of the strainer/coupler assembly  60 . In the strainer  204 , the downstream end  205  of the foraminate element  206  is open. In the exemplary embodiment, this open end is surrounded by a conduit  208  (e.g., a stainless steel tube with an upstream end  210  soldered to the exterior of the foraminate element and a downstream end  212  within a transverse conduit (e.g., a pipe)  220  extending through the sidewall of the sleeve  202 . One end  222  of the pipe  220  within the sleeve is closed. The other end  224  is coupled to a valve  226  (e.g., a lever-actuated ball valve threaded into the pipe end). In normal operation, the valve  226  is closed blocking communication through the pipe  220  and, thereby, the downstream end of the strainer  204 . The strainer operates as heretofore described. Periodically, however, the strainer may be flushed of solid contaminants by opening the valve  226  and, thereby permitting a flow from the interior of the strainer through the downstream end  205  and tube  212  into the pipe  220  and out an outlet  228  of the valve. This flushing flow may be maintained for an appropriate interval. Despite such flushing, periodically the strainer may still need to be replaced. Strainer replacement is eased by having a nonpermanent engagement between the strainer and the pipe  220 . In the exemplary embodiment, the tube  208  is closely fit within an aperture in the pipe sidewall with a clearance similar to or smaller than the mesh opening size of the strainer. This clearance advantageously permits easy removal of an old strainer and insertion of a new strainer without compromising filtration. 
   One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, details of any particular application may influence attributes of the strainer/coupler assemblies. Accordingly, other embodiments are within the scope of the following claims.