Hybrid thermal cycle with enhanced efficiency

Abstract

A flow of first working fluid (F 1 ) is provided to a boiler ( 203 ) to produce ( 104 ) a flow of first working fluid vapor. A second working fluid (F 2 ) in vaporous form is compressed ( 106 ), after which a third working fluid is formed by mixing ( 108 ) the first working fluid vapor and the second working fluid. Thermal energy is transferred ( 110 ) directly between the first and second working fluids in a mixing chamber ( 206 ) exclusive of any intervening structure. The third working fluid is expanded ( 112 ) to perform work, after which the first working fluid is extracted ( 114 ) as condensate, leaving a residual portion of the third working fluid. The cycle is repeated ( 116, 118, 120 ) using the condensate as the first working fluid and the residual portion as a constituent of the second working fluid.

We claim: 
     
         1 . A method for producing work from heat in a continuous cycle comprising:
 heating a pressurized flow of a first working fluid F 1  to form an F 1  vapor;   compressing an F 2  vapor comprised of a second working fluid F 2 ;   mixing said F 1  vapor and said F 2  vapor to form a third working fluid F 3 ;   within said third working fluid, transferring thermal energy directly between said F 1  vapor and said F 2  vapor, exclusive of any intervening structure;   expanding said third working fluid to perform useful work after or during said transferring;   cooling said third working fluid to extract a condensate comprised of F 1  and a residual portion of said third working fluid from which said condensate has been extracted; and   repeating said continuous cycle using said first working fluid F 1  obtained as said condensate, and using said residual portion as a constituent of the second working fluid F 2 .   
     
     
         2 . The method according to  claim 1 , further comprising pre-heating said pressurized flow of first working fluid F 1 , prior to said heating step. 
     
     
         3 . The method according to  claim 2 , further comprising using a high temperature flow of fluid from a high temperature thermal source to provide thermal energy for said heating step, and using a low temperature flow of fluid to provide thermal energy for said pre-heating step, wherein said low temperature flow is a downstream flow of said high temperature flow obtained after said high temperature flow has been used in said heating step. 
     
     
         4 . The method according to  claim 1 , wherein said heating step comprises:
 separating said first working fluid F 1  into at least an F 1 (1) flow and a F 1 (2) flow;   performing said heating step with respect to said F 1 (1) flow at a first temperature and first pressure to form a flow of F 1 (1) vapor;   performing said heating step with respect to said F 1 (2) flow at a second temperature and second pressure, different from said first temperature and first pressure, to form a flow of F 1 (2) vapor.   
     
     
         5 . The method according to  claim 4 , wherein said mixing step comprises mixing said F 2  vapor with said F 1 (1) vapor and said F 1 (2) vapor. 
     
     
         6 . The method according to  claim 4 , further comprising using a high temperature flow of fluid from a high temperature thermal source to provide thermal energy for heating said F 1 (2) flow, and using a low temperature flow of fluid to provide thermal energy for heating said F 1 (1) flow, wherein said low temperature flow is a downstream flow of said high temperature flow obtained after said high temperature flow has been used for heating said F 1 (2) flow. 
     
     
         7 . The method according to  claim 4 , further comprising heating a flow of said residual portion of F 3  together with said F 1 (1) flow at said first temperature and said first pressure. 
     
     
         8 . The method according to  claim 4 , further comprising transitioning said F 1 (1) flow from a higher pressure environment to a lower pressure environment, through an expansion valve, prior to said heating step. 
     
     
         9 . The method according to  claim 1 , further comprising expanding said F 1  vapor prior to said mixing step. 
     
     
         10 . The method according to  claim 1 , further comprising adding thermal energy to said third working fluid concurrent with said mixing. 
     
     
         11 . The method according to  claim 1 , further comprising adding a spray of liquid to said residual portion of F 3  before or during said compressing. 
     
     
         12 . The method according to  claim 11 , wherein said liquid is said first working fluid F 1 . 
     
     
         13 . The method according to  claim 11 , further comprising heating said residual portion of F 3  and said liquid spray, prior to said compressing. 
     
     
         14 . The method according to  claim 1 , further comprising combining at least a portion of said F 1 (1) vapor with said residual portion of F 3  prior to said compressing. 
     
     
         15 . The method according to  claim 1 , further comprising using a refrigeration cycle to cool said third working fluid F 3  to facilitate said extraction of said condensate. 
     
     
         16 . The method according to  claim 15 , wherein said refrigeration cycle is an internal refrigeration cycle which transports available thermal energy from the third working fluid F 3  to at least one of the first working fluid F 1  or the second working fluid F 2 . 
     
     
         17 . The method according to  claim 16 , further comprising implementing said internal refrigeration cycle using said condensate comprised of F 1  as a refrigerant to extract said available thermal energy from said third working fluid F 3 . 
     
     
         18 . The method according to  claim 16 , further comprising implementing said internal refrigeration cycle using said residual portion of said third working fluid as a refrigerant to extract said available thermal energy from said third working fluid F 3 . 
     
     
         19 . A system for producing work from heat in a continuous cycle comprising:
 at least one boiler configured to heat a pressurized flow of a first working fluid F 1  to form an F 1  vapor;   a compressor configured to compress an F 2  vapor comprised of a second working fluid F 2 ;   a mixing chamber configured to mix said F 1  vapor and said F 2  vapor which has been compressed to form a third working fluid F 3  and to facilitate a transfer of thermal energy directly between said F 1  vapor and said F 2  vapor, exclusive of any intervening structure;   an expander configured to expand said third working fluid to perform work after or during said transferring;   a condenser assembly configured to extract from said third working fluid F 3  a condensate comprised of F 1  and a residual portion of said third working fluid from which said condensate has been extracted.   
     
     
         20 . The system according to  claim 19 , further comprising a fluid communication system configured to facilitate repetition of said continuous cycle using said first working fluid F 1  obtained as said condensate, and using said residual portion as a constituent of the second working fluid F 2 . 
     
     
         21 . The system according to  claim 19 , further comprising a pre-heater configured to pre-heat said pressurized flow of first working fluid F 1 , prior to said heating step. 
     
     
         22 . The system according to  claim 21 , wherein said boiler is heated by a high temperature flow of fluid from a high temperature thermal source, said pre-heater is heated by a low temperature flow of fluid, and wherein said low temperature flow is a downstream flow of said high temperature flow obtained after said high temperature flow has been used in said heating step. 
     
     
         23 . The system according to  claim 19 , wherein said at least one boiler includes:
 a low pressure boiler configured to heat an F 1 (1) flow of said first working fluid at a first temperature and first pressure to form a flow of F 1 (1) vapor;   a high pressure boiler configured to heat an F 1 (2) flow of said first working fluid at a second temperature and second pressure, different from said first temperature and first pressure, to form a flow of F 1 (2) vapor.   
     
     
         24 . The system according to  claim 23 , wherein said mixing chamber is configured to mix said F 2  vapor with said F 1 (1) vapor and said F 1 (2) vapor. 
     
     
         25 . The system according to  claim 23 , wherein said high pressure boiler is configured to be heated using a high temperature flow of fluid from a high temperature thermal source for heating said F 1 (2) flow, said low pressure boiler is configured to be heated by a low temperature flow of fluid to provide thermal energy for heating said F 1 (1) flow, and wherein said low temperature flow is a downstream flow of said high temperature flow obtained after said high temperature flow has been used for heating said F 1 (2) flow. 
     
     
         26 . The system according to  claim 19 , further comprising an F 1  expander configured to expand said F 1  vapor before said F 1  vapor is communicated to said mixing chamber. 
     
     
         27 . The system according to  claim 23 , wherein said low pressure boiler is configured to heat a flow of said residual portion of F 3  together with said F 1 (1) flow at said first temperature and said first pressure. 
     
     
         28 . The system according to  claim 23 , further comprising a compressor or vacuum pump configured to maintain said first a pressure within said low pressure boiler, and an expansion valve configured to restrict said F 1 (1) flow entering said low pressure boiler. 
     
     
         29 . The system according to  claim 19 , wherein said mixing chamber is configured to receive a supply of thermal energy and to communicate said supply of thermal energy to said third working fluid. 
     
     
         30 . The system according to  claim 19 , further comprising a spray cooling system configured to add a spray of a liquid to said residual portion of F 3  before or during compressing operations performed by said compressor. 
     
     
         31 . The system according to  claim 30 , wherein said liquid is said first working fluid F 1 . 
     
     
         32 . The system according to  claim 30 , further comprising a heat exchanger configured to heat said residual portion of F 3  and said liquid spray, prior to said compressing operations performed by said compressor. 
     
     
         33 . The system according to  claim 19 , wherein a fluid flow path is configured to combine at least a portion of said F 1 (1) vapor with said residual portion of F 3  prior to performing compressing operations by said compressor. 
     
     
         34 . The system according to  claim 19 , further comprising a refrigeration apparatus configured to cool said third working fluid F 3  to facilitate said extraction of said condensate. 
     
     
         35 . The system according to  claim 34 , wherein said refrigeration apparatus comprises an internal refrigeration cycle which transports available thermal energy from the third working fluid F 3  to at least one of the first working fluid F 1  or the second working fluid F 2 . 
     
     
         36 . The system according to  claim 35 , wherein said refrigeration apparatus is configured to use said condensate comprised of F 1  as a refrigerant to extract available thermal energy from said third working fluid F 3 . 
     
     
         37 . The system according to  claim 35 , wherein said refrigeration apparatus is configured to use said residual portion of said third working fluid as a refrigerant to extract said available thermal energy from said third working fluid F 3 .