Rankine cycle system

Abstract

The rankine cycle system includes an evaporator coupled to a heat source and configured to circulate a working fluid in heat exchange relationship with a hot fluid from the heat source so as to heat the working fluid and vaporize the working fluid. An expander is coupled to the evaporator and configured to expand the vaporized working fluid from the evaporator. The exemplary expander is operable at variable speed. A condenser is coupled to the expander and configured to condense the vaporized working fluid from the expander. A pump is coupled to the condenser and configured to feed the condensed working fluid from the condenser to the evaporator.

1 . A rankine cycle system, comprising:
 an evaporator coupled to a heat source and configured to circulate a working fluid in heat exchange relationship with a hot fluid from the heat source so as to heat the working fluid and vaporize the working fluid;   an expander coupled to the evaporator and configured to expand the vaporized working fluid from the evaporator; wherein the expander is operable at variable speed;   a condenser coupled to the expander and configured to condense the vaporized working fluid from the expander;   a pump coupled to the condenser and configured to feed the condensed working fluid from the condenser to the evaporator.   
     
     
         2 . The system of  claim 1 , wherein the working fluid comprises cyclohexane, cyclopentane, thiophene, ketones, aromatics, propane, butane, pentafluoro-propane, pentafluoro-butane, pentafluoro-polyether, or combinations thereof. 
     
     
         3 . The system of  claim 1 , wherein the expander comprises at least one radial type expander, axial type expander, high temperature screw type or impulse type expander, positive displacement type expander. 
     
     
         4 . The system of  claim 1 , wherein the expander comprises a multi-stage screw expander. 
     
     
         5 . The system of  claim 1 , wherein the expander is a multi-screw expander. 
     
     
         6 . The system of  claim 1 , wherein the expander is directly coupled to at least one asynchronous generator configured to generate power. 
     
     
         7 . The system of  claim 6 , wherein the asynchronous generator is operable at variable speed to vary the speed of the expander. 
     
     
         8 . The system of  claim 7 , further comprising a frequency inverter configured to vary the speed of the asynchronous generator. 
     
     
         9 . The system of  claim 1 , wherein the expander is coupled via a gearbox to at least one asynchronous generator configured to generate power. 
     
     
         10 . The system of  claim 9 , wherein a gear ratio of the gearbox is variable to vary the speed of the expander. 
     
     
         11 . A waste heat recovery system including at least two integrated rankine cycle systems, the recovery system comprising:
 a heat generation system comprising at least two separate heat sources having different temperatures;   a first rankine cycle system comprising a first expander, wherein the first rankine cycle system is coupled to a first heat source among the at least two separate heat sources and configured to circulate a first working fluid; wherein the first rankine system is configured to remove heat from the first heat source; wherein the first expander is operable at variable speed;   a second rankine cycle system comprising a second expander; wherein the second rankine cycle system is coupled to at least one second heat source among the at least two separate heat sources and configured to circulate a second working fluid, the at least one second heat source comprising a lower temperature heat source than the first heat source, wherein the second rankine cycle system is configured to remove heat from the at least one second heat source; wherein the second expander is operable at variable speed; and   a cascaded heat exchange unit, wherein the first and second working fluids are circulatable in heat exchange relationship through the cascaded heat exchange unit for condensation of the first working fluid in the first rankine cycle system and evaporation of the second working fluid in the second rankine cycle system.   
     
     
         12 . The system of  claim 11 , wherein the first working fluid comprises cyclohexane, cyclopentane, thiophene, ketones, aromatics, or combinations thereof. 
     
     
         13 . The system of  claim 11 , wherein the first expander comprises at least one radial type expander, axial type expander, high temperature screw type or impulse type expander, positive displacement type expander. 
     
     
         14 . The system of  claim 11 , wherein the first expander comprises a multi-stage screw expander. 
     
     
         15 . The system of  claim 11 , wherein the first expander is a multi-screw expander. 
     
     
         16 . The system of  claim 11 , wherein the first expander is directly coupled to at least one asynchronous generator configured to generate power. 
     
     
         17 . The system of  claim 16 , further comprising a frequency inverter configured to vary the speed of the asynchronous generator. 
     
     
         18 . The system of  claim 11 , wherein the expander is coupled via a gearbox to at least one asynchronous generator configured to generate power. 
     
     
         19 . The system of  claim 18 , wherein a gear ratio of the gearbox is variable to vary the speed of the expander. 
     
     
         20 . The system of  claim 11 , wherein the second organic working fluid comprises propane, butane, pentafluoro-propane, pentafluoro-butane, pentafluoro-polyether, oil, or combinations thereof. 
     
     
         21 . The system of  claim 11 , wherein the second expander comprises at least one radial type expander, axial type expander, high temperature screw type or impulse type expander, positive displacement type expander. 
     
     
         22 . The system of  claim 11 , wherein the second expander comprises a multi-stage screw expander. 
     
     
         23 . The system of  claim 11 , wherein the second expander is directly coupled to at least one asynchronous generator configured to generate power. 
     
     
         24 . The system of  claim 23 , further comprising a frequency inverter configured to vary the speed of the asynchronous generator. 
     
     
         25 . The system of  claim 11 , wherein the second expander is coupled via a gearbox to at least one asynchronous generator configured to generate power. 
     
     
         26 . The system of  claim 25 , wherein a gear ratio of the gearbox is variable to vary the speed of the expander.