Method and system for converting thermal power, delivered from a variable temperature heat source, into mechanical power

Abstract

The present invention concerns a method and a system for converting thermal power delivered from a variable temperature heat source into mechanical power by means of a closed thermodynamic cycle. The cycle is characterized in that it operates between a higher temperature (Thigh) and a temperature substantially equal to ambient temperature (Tamb), wherein said higher temperature (Thigh) is much higher than ambient temperature (Tamb), said closed thermodynamic cycle comprising an adiabatic compression process for changing the temperature of a two-phase mixture from said ambient temperature (Tamb) to a lower temperature (Tlow) and to change the specific entropy value of one phase of said two-phase mixture from a first specific entropy value (si, s3) to a second specific entropy value (s2), said second specific entropy value (s2) being lower than said first specific entropy value (s1, s3) and said ambient temperature value (Tamb) being lower than the value of said lower temperature (Tlow).

1 . A method for converting thermal power delivered from a variable temperature heat source into mechanical power by means of a closed thermodynamic cycle, characterized in that said closed thermodynamic cycle operates between a higher temperature and a temperature substantially equal to ambient temperature, wherein said higher temperature is much higher than ambient temperature, said closed thermodynamic cycle comprising an adiabatic compression process for changing the temperature of a two-phase mixture from said ambient temperature to a temperature lower or equal to a first temperature, said first temperature being higher than said ambient temperature and lower than said higher temperature, and to change the specific entropy value of one phase of said two-phase mixture from a first specific entropy value to a second specific entropy value, said second specific entropy value being lower than said first specific entropy value, said two-phase mixture is obtained by a mixing process, for mixing a first working fluid with a second working fluid, said second working fluid comprises a non-volatile liquid. 
     
     
         2 . A method as claimed in  claim 1 , wherein said two-phase mixture is obtained by a mixing process, for mixing a first working fluid with a second working fluid, said two-phase mixture having a ratio of 0.1 to 1000, preferably 10 kg of said second working fluid per one kg of said first working fluid. 
     
     
         3 . A method as claimed in  claim 2 , wherein said mixing process comprises a spraying process, for spraying said second working fluid with said first working fluid. 
     
     
         4 . A method as claimed in  claim 1 , wherein after said adiabatic compression process of said two : phase mixture, said closed thermodynamic cycle comprises a separation process for separating said first working fluid from said second working fluid. 
     
     
         5 . A method as claimed in  claim 1 , wherein said adiabatic compression process of said two-phase mixture ends at a second temperature and at first pressure, wherein said second temperature is higher than said ambient temperature and lower than said first temperature. 
     
     
         6 . A method as claimed in  claim 5 , wherein said closed thermodynamic cycle, after said separation process for separating said first working fluid from said second working fluid, comprises a process of adiabatic compression process of said first working fluid from said second temperature and said first pressure to said first temperature at a second pressure. 
     
     
         7 . A method as claimed in  claim 6 , wherein said closed thermodynamic cycle comprises a process of isobaric heating of said first working fluid at said second pressure to change it from said first temperature to said higher temperature. 
     
     
         8 . A method as claimed in  claim 7 , wherein said closed thermodynamic cycle comprises a process of adiabatic expansion of said first working fluid from said higher temperature and said second pressure to a temperature higher or equal to said ambient temperature. 
     
     
         9 . A method as claimed in  claim 8 , comprises an adiabatic expansion process of said first working fluid from said higher temperature and said second pressure ends at a third temperature that is higher than said ambient temperature and to a third pressure. 
     
     
         10 . A method as claimed in  claim 9 , wherein after said process of adiabatic expansion of said first working fluid, the thermodynamic cycle comprises an isobaric cooling process at said third pressure of said first fluid from said third temperature to said ambient temperature, said specific entropy value of said phase of said two-phase mixture changing from said first specific entropy value to a third specific entropy value, said third specific entropy value being lower than said first specific entropy value. 
     
     
         11 . A method as claimed in  claim 4 , wherein said closed thermodynamic cycle, after said separation process for separating said first working fluid from said second working fluid, comprises a process of isobaric cooling of said non-volatile liquid to change it from said second temperature to said ambient temperature. 
     
     
         12 . A method as claimed in  claim 1 , wherein said first fluid comprises a non-soluble gas. 
     
     
         13 . A method as claimed in  claim 12 , wherein said non-soluble gas is selected from the group comprising monatomic gases. 
     
     
         14 . A method as claimed in  claim 1 , wherein said non-volatile liquid is selected from the group comprising vegetable, mineral or synthetic lubricating oils. 
     
     
         15 . A method as claimed in  claim 1 , wherein said higher temperature ranges from 400 to 800° C., said ambient temperature is equal to the temperature of the site in which said closed thermodynamic cycle operates, and said first temperature is a free parameter of the closed thermodynamic cycle and preferably ranges from 80 to 120° C. 
     
     
         16 - 27 . (canceled)