Expansion device for use in a working medium circuit and method for operating an expansion device

Abstract

In an expansion device for use in a working medium circuit, for performing a process sequence corresponding to that of a Clausius Rankine cycle or an Organic Rankine cycle, a working unit comprising two interleaved scroll elements is provided of which one is stationary whereas the other is supported for orbiting relative to the stationary scroll element so as to form separate expansion regions between the scrolls moving, upon orbiting of the movable scroll, from the center of the interleaved scroll elements circularly outwardly with increasing volumes in which a working medium admitted at the center can expand for driving the movable scroll element.

1 . An expansion device ( 1 ) for use in a working medium circuit (AK) for performing a process sequence within the working medium circuit, said process sequence corresponding to a Clausius Rankine cycle or Organic Rankine cycle, said expansion device ( 1 ) comprising a scroll-type working unit, through which a working medium (AM) flowing in the working medium circuit (AK) is conducted in the expansion direction, with an expansion ratio of the scroll-type working unit and an adjustable supply of working medium (AM) delivered to the scroll-type working unit. 
     
     
         2 . The expansion device ( 1 ) according to  claim 1 , further comprising a fixed scroll element ( 2 ), a movable scroll element ( 3 ) and an eccentric drive, with the fixed scroll element ( 2 ) having a fixed scroll base plate ( 4 ) and a fixed scroll spiral wall ( 5 ) extending from the fixed scroll base plate ( 4 ), the movable scroll element ( 3 ) comprising a movable scroll base plate ( 7 ) and a scroll spiral wall ( 8 ), supported by a crank scroll base plate ( 7 ) so as to be movable therewith, the movable scroll spiral wall ( 8 ) and the fixed scroll spiral wall ( 5 ) being in engagement with each other, so that at least one expansion region ( 9 . 1  to  9 . 5 ) is formed between the movable scroll element ( 3 ) and the fixed scroll element ( 2 ), the movable scroll element ( 3 ) moving relative to the fixed scroll element ( 2 ) by means of the eccentric drive, and the size of the expansion region ( 9 . 1  to  9 . 5 ) being changeable during the circular movement of the at least one expansion region ( 9 . 1  to  9 . 5 ) along an expansion path. 
     
     
         3 . The expansion device ( 1 ) according to  claim 1 , wherein the working medium (AM) of the working medium circuit (AK) is supplied to the expansion device through an opening formed in the center of the fixed scroll base plate ( 4 ). 
     
     
         4 . The expansion device ( 1 ) according to  claim 1 , wherein the working medium (AM) of the working medium circuit (AK) is supplied by way of a central inlet ( 6 . 1 ) in the fixed scroll base plate ( 4 ). 
     
     
         5 . The expansion device ( 1 ) according to  claim 1 , wherein additional working medium (AM) of the working medium circuit (AK) is supplied by means of further inlets ( 6 . 2  to  6 . 5 ) in the fixed scroll base plate ( 4 ) along the expansion path. 
     
     
         6 . The expansion device ( 1 ) according to  claim 1 , wherein at least one cycle valve is provided for controlling the supply of the working medium (AM) to the working medium circuit (AK). 
     
     
         7 . The expansion device ( 1 ) according to  claim 6 , wherein a separate cycle valve is provided for each inlet ( 6 . 1  to  6 . 5 ) formed in the fixed scroll base plate ( 4 ). 
     
     
         8 . The expansion device ( 1 ) according to  claim 1 , wherein an expansion pressure gradient within the expansion device ( 1 ) is dependent upon the geometry of the scroll spiral walls ( 5  and  8 ). 
     
     
         9 . The expansion device ( 1 ) according to  claim 2 , wherein the scroll spiral walls ( 5  and  8 ) are in the form of Archimedean spiral surfaces. 
     
     
         10 . A method for operating an expansion device ( 1 ) in a working medium circuit (AK), wherein a process sequence is carried out within the working medium circuit (AK) which corresponds to that of a Clausius Rankine cycle or an Organic Rankine cycle, said method comprising the steps of:
 moving a movable scroll element ( 3 ) relative to a fixed scroll element ( 2 ) by means of an eccentric drive in a orbital movement so as to change the size of expansion regions ( 9 . 1  to  9 . 5 ) formed between the movable scroll element ( 3 ) and the fixed scroll element ( 2 ) during the orbital movement along an expansion path formed between the scroll elements ( 2 ,  3 ).