Effect of pressure pulsation on COP in two-stage-compression vapor-injection cycle.

This  paper  describes  experimental  results  of  COP  characteristics  of  two-­stage-­compression  vapor-­ injection  cycle  against  the  injection  pipe  length.  Theoretically,  the  mass  flow  rate  of  vapor  injection is  determined  by  the  pressure  difference  between  a  separator  and  a  compressor’s  injection  port. However,  the  pressure  pulsation  of  the  compressor  oscillates  the  pressure  difference  and  changes the  COP  of  this  cycle.  In  this  study,  in  order  to  reveal  this  effect  on  COP  experimentally,  COP characteristics  were  investigated  by  changing  the  injection  pipe  length.  The  results  show  that  the COP  varies  cyclically  depending  on  the  injection  pipe  length  and  this  is  caused  by  resonance  of pressure  wave  in  the  injection  pipe.