Abstract:
A recuperator core has a plurality of passages sealingly formed therein. In use, a fluid passes through a respective one of the plurality of passages under pressure. The recuperator core must be tested to determine an operational efficiency or leakage within the respective plurality of passages. A pair of sealing mechanisms are positioned at a respective one a pair of ends of the respective one of the plurality of passages. A pressure or a vacuum is pulled across the respective ones of plurality of passages and a rate of leakage or decay rate is monitored to define an operational recuperator core and a failed recuperator core.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates generally to a heat exchanger or more explicitly to a recuperator and more particularly to a method and an apparatus for testing the leakage within a core of the recuperator.  
         BACKGROUND  
         [0002]    Many gas turbine engines use a heat exchanger or recuperator to increase the operation efficiency of the engine by retracting heat from the exhaust gas and preheating the intake air. Typically, a recuperator for a gas turbine engine must be capable of operating at temperatures of between about 500 degrees C. and 700 degrees C. and internal pressures of between approximately 450 kPa and 1400 kPa under operating conditions involving repeated starting and stopping cycles.  
           [0003]    A recuperator is made from a plurality of cells. The cell is made from a plurality of components parts. The assembly of the plurality of cells form a core having a donor passage and a recipient passage. The components of the cell are welded together and tested for leakage and the plurality of cells are welded together forming the core. An example of such a plurality of welded cells resulting in the core is shown in U.S. Pat. No. 5,060,721 issued on Oct. 29, 1991 to Charles T. Darragh.  
           [0004]    As stated above, during the assembly of the cells and the recuperator core, the interface of the components are welded. The effectiveness of the welding process used to form the core is in many instances depend on the fitting relationship of the plurality of cells, the resulting configuration of the interface of the individual ones of the plurality of cells and the welding process itself. The results of these variables in some instances results in a leaking core, leakage between the donor passage and the recipient passage. Thus, it is necessary to inspect or check the reliability of the welded core against leaks prior to installing into the recuperator application. The inspection process adds cost to the finished core, which to insure reliability may be necessary, but the cost effectiveness of such an inspection process can reduce profitability. Inspection or checking must be done in a reliable and cost effective manner.  
           [0005]    The present invention is directed to overcome one or more of the problems as set forth above.  
         SUMMARY OF THE INVENTION  
         [0006]    In one aspect of the invention, an apparatus for testing a leakage rate within a recuperator core is disclosed. The recuperator core has a plurality of components, such components being a plurality of cells being welded one to another. The apparatus has a platform defining a first end and a second end. A first surface of the platform extends between the first end and the second end. A first support portion is attached to the first surface and a second support portion is spaces from the first support portion and each being attached to the first surface. A pair of sealing mechanisms, at least one of the pair of sealing mechanisms being movable between an open or non testing position and a closed or testing position. In the closed or testing position a reservoir is formed. A pump being operatively connected to at least one of the pair of sealing mechanisms. A monitoring system being operatively connected to the platform, the pair of sealing mechanisms, the reservoir and the pump. And, a readout station being operatively connected to the monitoring system, the reservoir and the pump.  
           [0007]    In another aspect of the invention, a method of testing a recuperator core is disclosed. The recuperator core has a plurality of donor passages defining a donor inlet end and a donor outlet end and a plurality of recipient passages defining a recipient inlet end and a recipient outlet end. The plurality of donor passages are sealed from the plurality of recipient passages. The method of testing the recuperator core has the steps of positioning the recuperator core in a test stand; positioning a sealing member in sealing relationship with one of the donor inlet end and the recipient inlet end and positioning an other of the sealing member in sealing relationship with one of the donor outlet end and the recipient outlet end forming a reservoir and defining a closed or testing position; actuating a controller applying one of a pressure and a vacuum to the reservoir; monitoring a rate of decay of the pressure and the vacuum; and displaying the rate of decay. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a view of a recuperator core being partially sectioned;  
         [0009]    [0009]FIG. 2 is a generally schematic view of a leak testing system; and  
         [0010]    [0010]FIG. 3 is a detailed view of a test station; 
     
    
     DETAILED DESCRIPTION  
       [0011]    As best shown in FIG. 1, a recuperator core  10  is formed from a plurality of cells  12 . In this application, the recuperator core  10  has a circular shape and a cylindrical configuration, however, as an alternative any configuration of a recuperator core  10  can be tested. For example, the geometric shape or configuration of the recuperator could be a square, a trapezoidal or a rectangular, without changing the jest of the invention. The recuperator core  10  has a plurality of donor passages  14  and a plurality of recipient passages  16  defined therein. Each of the plurality of donor passages  14  has a donor inlet end  18  and a donor outlet end  20 . Each of the plurality of recipient passages  16  has a recipient inlet end  22  and a recipient outlet end  24 . The circular core  10  defines a central axis “A”, an inside diameter “ID” and an outside diameter “OD”. A plurality of welds  26  are used to complete the assembly of each of the plurality of cells  12 . Additional welds  26 , not shown, are used in forming and combining the plurality of cells  12  forming the circular recuperator core  10 .  
         [0012]    As best shown in FIG. 2, a system, apparatus and/or assembly line  30  has an input end or station  32 , a testing station  34 , a control panel or operations station  36 , a vacuum or pressure station  38  and an output end or station  40  operatively connected one with the other. The input end or station  32  has a tub or flat  50  positioned near the testing station  34 . In this application, as best shown in FIG. 3, the testing station  34  is positioned on a table or movable cart  52 . The cart  52  has a top portion  54  on which is positioned a test stand  56 . A bottom portion  58  of the cart  52  has a set of rotatable wheels  60  attached thereto. The control panel  36  is operatively connected to the cart  52 , such as by wires, and has a plurality of switches  62  operatively positioned therein. In this application, the control panel  36  is physically attached to the cart  52  and moves with the cart  52 . A portion of the plurality of switches  62  are safety switches. The control panel  36  also has a monitoring system  64  operatively attached to the testing station  34  and the vacuum or pressure station  38 . Another portion of the plurality of switches  62  are operatively connected to the test stand  56  of the testing station  34 , the vacuum or pressure station  38  and the monitoring system  64 , such as by wires. The vacuum or pressure station  38  has a source for pulling a vacuum or applying a pressure, a pump  66  and a plurality of lines  68  interconnected with the testing station  34 . The monitoring system  64  has a plurality of sensors  70  operatively connected to the vacuum or pressure pump  66 , the testing station  34  and the plurality of switches  62 . The output end or station  40  has a pair of tubs or flats  72  positioned near the testing station  34 . One of the pair of tubs or flats  72  defines an acceptable or operational position  74  for the core  10  to be placed thereon and the other of the pair of tubs or flats  72  defines a non acceptable or failed position  76  for the core  10  to be placed thereon.  
         [0013]    The test stand  56  has a platform  80  defining a first end  82  and a second end  84 . A first surface  86  of the platform  80  extends between the first end  82  and the second end  84 . The first surface  86  is attached to the top portion  54  of the cart  32 . A second surface  88  of the platform  80  is spaced from the first surface  84  a preestablished distance and extends between the first end  82  and the second end  84 . A first support portion  90  of the test stand  65  has a first end  92  attached to the second surface  88  near the first end  82 . A pair of brace members  94  are interposed the first support portion  90  and the first end  82 . A second support portion  96  has a first end  98  attached to the second surface  88  near the second end  84 . An other pair of brace members  100  are interposed the second support portion  96  and the second end  84 . The first support portion  90  and the second support portion  96  are spaced apart a preestablished axial distance “D”. In this application, a brace  98  extends between a second end  102  of the first support portion  90  and a second end  104  of the second support portion  96 . The first support portion  90  has a sealing member  110  attached thereto which operatively communicates with the core  10 . The first support portion  90  has a valve member  114  attached thereto. A first end  116  of a pressure member  118 , such as a cylinder  120 , is operatively attached to the second support portion  96 . A rod end  121  of the pressure member  118  is attached to a plate  122 . The plate  122  is moved along the axial distance “D” and has an infinite number of positions. A sealing member  124  is attached to the plate  122 . A source of flow  126 , such a hydraulic pump or air compressor activates the cylinder  120  within the distance “D”. The sealing member  124  is movable between an open or non-testing position  127  and a closed or testing position  128 . With the sealing member  110 , the core  10  and the sealing member  124  in the closed or testing position, a reservoir  125  is formed therebetween. The valve member  114  and the source for pulling a vacuum or applying a pressure, the pump  66  are operatively connected to the reservoir  125 . As an alternative, the sealing member  110  could be movable forming the open or non-testing position  127  and the closed or testing position  128 .  
         [0014]    The test stand  56 , used for testing the circular core  10  of this application, has a guard member  130  attached therearound. The guard member  130  has a band portion  132  extending between a first end  134  and a second end  136 . A tightening member  138  extends between the first end  134  and the second end  136 . In this application, the tightening member  138  has a threaded boss member  140  attached to one of the ends  134 , 136 , a stationary member  142  attached to the other of the ends  134 , 136  and a threaded member  144  having a hex end  148  thereon extending between the threaded boss member  140  and the stationary member  142 .  
         [0015]    The monitoring system  64 , in this application, is operated by using a controller  150 , such as a computer and a self guided program, not shown. The program directs an operator through a testing operation which defines a plurality of steps. With input from the operator, the controller  150  defines a plurality of parameters. The plurality of steps and the plurality of parameters in the testing operation can be controlled manually or automatically. The operator identifies the core  10  to be tested, a first time test of the core  10  or a multiple test of a used or reworked core  10 . The results of the test is recorded and stored within a readout station  152 . A plurality of lights and/or signals  154  indicate to the operator the results of the test. The results of the test indicate a decay rate of the core  10 . The results of the test can be printed on a hard copy and/or the results can be visually marked on the core  10 . For example, the visual marking is normally applied to the “ID” or the “OD” of the core  10  by marker  156 .  
         [0016]    Industrial Applicability  
         [0017]    In operation, as best shown in FIG. 3, one of the cores  10  is removed from the tub  50  at the input end or station  32 . The core  10  is positioned on the platform  80  of the test stand  56 . The guard member  130  is positioned about the “OD” of the core  10  and the threaded member  144  of the tightening member  138  is threadedly engaged with the threaded boss member  140  maintaining the guard member  130  about the “OD” of the core  10  in a fixed position.  
         [0018]    The core  10  and the guard member  130  are positioned between the first support portion  90  and the second support portion  96 . The central axis “A” of the core  10  is positioned generally centered on each of the sealing member  110  attached to the first support portion  90  and the sealing member  124  attached to the second support portion  96 . The source of flow  126  is activated by the operator administrating the appropriate one of the plurality of switches  62  and the plate  122  is moved axially by the cylinder  120 . Thus, each of the sealing member  110  and the sealing member  124  sealingly contact the core  10  at opposite ends. And, the reservoir  125  is formed.  
         [0019]    The operator actuates the program by using the control panel  36  and the system  30  is directed through the testing operation. For example, the operator defines and inputs the plurality of testing parameters. The identify of the core  10 , serial number, first time test, multiple test or used core  10  is identified. And, the program precedes through the steps of the procedure. The results of the test is recorded and stored for future use and in most situations is printed on a hard copy. In some tests, the results of the test are stamped or visually marked on the core  10  itself. The test substantially uses a flow from the vacuum or pressure station  38  which enters or exits through the lines  68 . After the pressure or vacuum, within the reservoir  125 , reaches a predetermined value, the monitoring system  64  defines the rate of leakage within the plurality of donor passage  14  and/or plurality of recipient passages  16  and records the rate of leakage for future use. The plurality of light and/or signals  152  indicate to the operator the results of the test.  
         [0020]    The operator then removes the core  10  from between the first support portion  90  and the second support portion  96 . By actuating one of the plurality of switches  62 , the pressure in the cylinder  120  is relived allowing the core  10  and the guard member  130  to be removed. The operator removes the guard member  130  by loosening the threaded member  144  from the threaded boss member  140  and the core  10  is placed in the appropriate one of the operational core  10  position  74  and the failed core  10  position  76  at the output end  40 . The failed or rejected core  10  are, where feasible, reworked to overcome their deficiencies and retested.  
         [0021]    Thus, an efficient and effective method is used to test the reliability of the core  10 . The method has proven to be a reliable and cost effective operation. The leakage rate of each core  10  is determined and recorded. Thus, if during the longevity of the core  10 , the efficiency is found to have been reduced the core  10  can be retested to confirm or rebut the suspected loss in efficiency. Furthermore, the reduction in efficiency can be monitored and improvements can be setforth.  
         [0022]    Other aspects and advantages of this invention ca be obtained from a study of the drawings, the disclosure, and the appended claims.