Rankine cycle system

Abstract

A Rankine cycle system includes: an evaporator for heating water with thermal energy of exhaust gas of an engine so as to generate steam; an expander for converting the thermal energy of the steam generated by the evaporator into mechanical energy; and a distribution device for manipulating the amount of water supplied to the evaporator in order to make the temperature of the steam supplied from the evaporator to the expander coincide with a target temperature. The distribution device controls a distribution ratio between the amount of water supplied to the entrance of the evaporator and the amount of water supplied to a portion partway along the evaporator, thereby suppressing an overshoot in the temperature of the gas-phase working medium due to a sudden increase in the thermal energy of the exhaust gas.

1 . A Rankine cycle system comprising: 
 an evaporator for heating a liquid-phase working medium with thermal energy of exhaust gas of an engine so as to generate a gas-phase working medium;    an expander for converting the thermal energy of the gas-phase working medium generated by the evaporator into mechanical energy; and    temperature control means for manipulating the amount of liquid-phase working medium supplied to the evaporator in order to make the temperature of the gas-phase working medium supplied from the evaporator to the expander coincide with a target temperature,    wherein the temperature control means controls a distribution ratio between the amount of liquid-phase working medium supplied to the entrance of the evaporator and the amount of liquid-phase working medium supplied to a portion partway along the evaporator.    
   
   
       2 . The Rankine cycle system according to  claim 1 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio when the thermal energy of the exhaust gas changes suddenly accompanying a change in load of the engine and the temperature of the gas-phase working medium cannot be controlled at the target temperature by supplying the liquid-phase working medium only from the entrance of the evaporator.  
   
   
       3 . The Rankine cycle system according to  claim 1 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio when the temperature of the gas-phase working medium supplied from the evaporator to the expander is higher than the target temperature.  
   
   
       4 . The Rankine cycle system according to  claim 2 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio when the temperature of the gas-phase working medium supplied from the evaporator to the expander is higher than the target temperature.  
   
   
       5 . The Rankine cycle system according to  claim 1 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       6 . The Rankine cycle system according to  claim 2 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       7 . The Rankine cycle system according to  claim 3 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       8 . The Rankine cycle system according to  claim 4 , wherein the temperature control means supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       9 . The Rankine cycle system according to  claim 5 , wherein at least when the air/fuel ratio is stoichiometric, the temperature control means increases the distribution ratio of the liquid-phase working medium to a portion partway along the evaporator as compared with the case of another air/fuel ratio.  
   
   
       10 . The Rankine cycle system according to  claim 6 , wherein at least when the air/fuel ratio is stoichiometric, the temperature control Scans increases the distribution ratio of the liquid-phase working medium to a portion partway along the evaporator as compared with the case of another air/fuel ratio.  
   
   
       11 . The Rankine cycle system according to  claim 7 , wherein at least when the air/fuel ratio is stoichiometric, the temperature control means increases the distribution ratio of the liquid-phase working medium to a portion partway along the evaporator as compared with the case of another air/fuel ratio.  
   
   
       12 . The Rankine cycle system according to  claim 8 , wherein at least when the air/fuel ratio is stoichiometric, the temperature control means increases the distribution ratio of the liquid-phase working medium to a portion partway along the evaporator as compared with the case of another air/fuel ratio.  
   
   
       13 . A Rankine cycle system comprising: 
 an evaporator for heating a liquid-phase working medium with thermal energy of exhaust gas of an engine so as to generate a gas-phase working medium;    an expander for converting the thermal energy of the gas-phase working medium generated by the evaporator into mechanical energy; and    a temperature controller for manipulating the amount of liquid-phase working medium supplied to the evaporator in order to make the temperature of the gas-phase working medium supplied from the evaporator to the expander coincide with a target temperature,    wherein the temperature controller controls a distribution ratio between the amount of liquid-phase working medium supplied to the entrance of the evaporator and the amount of liquid-phase working medium supplied to a portion partway along the evaporator, and further including a feedforward liquid-phase working medium calculator for calculating a feedforward of the liquid-phase working medium based on operating conditions and a feedback liquid-phase working medium calculator for calculating a feedback of the liquid-phase working medium based on the target temperature.    
   
   
       14 . The Rankine cycle system according to  claim 13 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio when the thermal energy of the exhaust gas changes suddenly accompanying a change in load of the engine and the temperature of the gas-phase working medium cannot be controlled at the target temperature by supplying the liquid-phase working medium only from the entrance of the evaporator.  
   
   
       15 . The Rankine cycle system according to  claim 13 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio when the temperature of the gas-phase working medium supplied from the evaporator to the expander is higher than the target temperature.  
   
   
       16 . The Rankine cycle system according to  claim 14 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio when the temperature of the gas-phase working medium supplied from the evaporator to the expander is higher than the target temperature.  
   
   
       17 . The Rankine cycle system according to  claim 13 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       18 . The Rankine cycle system according to  claim 14 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       19 . The Rankine cycle system according to  claim 15 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       20 . The Rankine cycle system according to  claim 16 , wherein the temperature controller supplies the liquid-phase working medium to a portion partway along the evaporator at a predetermined distribution ratio according to an air/fuel ratio.  
   
   
       21 . The Rankine cycle system according to  claim 17 , wherein at least when the air/fuel ratio is stoichiometric, the temperature controller increases the distribution ratio of the liquid-phase working medium to a portion partway along the evaporator as compared with the case of another air/fuel ratio.  
   
   
       22 . The Rankine cycle system according to  claim 18 , wherein at least when the air/fuel ratio is stoichiometric, the temperature controller increases the distribution ratio of the liquid-phase working medium to a portion partway along the evaporator as compared with the case of another air/fuel ratio.