Direct evaporator system and method for organic rankine cycle systems

Abstract

Systems and methods include heat exchangers using Organic Rankine Cycle (ORC) fluids in power generation systems. A system for power generation using an ORC comprises: a heat exchanger configured to be mounted entirely inside a duct, the heat exchanger comprising a single inlet which traverses from an outer side of the duct to an inner side of the duct, a single outlet which traverses from the inner side of the duct to the outer side of the duct, and a conduit connecting the single inlet to the single outlet, the conduit being provided entirely inside the duct.

What is claimed is: 
     
         1 . A system for power generation using an Organic Rankine Cycle (ORC), the system comprising:
 a heat exchanger configured to be mounted entirely inside a duct, the heat exchanger comprising:   a single inlet which traverses from an outer side of the duct to an inner side of the duct;   a single outlet which traverses from the inner side of the duct to the outer side of the duct; and   a conduit between the single inlet and the single outlet, the conduit being provided entirely inside the duct,   wherein the heat exchanger is configured to receive an ORC fluid at the single inlet as a pressurized liquid at a pressure greater than or equal to a critical pressure of the ORC fluid, to heat the ORC fluid to a temperature greater than or equal to a critical temperature of the ORC fluid, and to exit the ORC fluid through the single outlet as a supercritical fluid, and   wherein the supercritical fluid is defined by the temperature being greater than the critical temperature and the pressure being greater than the critical pressure.   
     
     
         2 . The system of  claim 1 , wherein the critical pressure and critical temperature for the ORC fluid define a point at which the ORC fluid becomes supercritical. 
     
     
         3 . The system of  claim 1 , wherein the ORC fluid is selected from a group comprising pentane, propane, cyclohexane, butane, a fluorohydrocarbon, a ketone, an aromatic, or a combination thereof. 
     
     
         4 . The system of  claim 1 , wherein the ORC fluid is heated to a temperature greater than or equal to the critical temperature of the ORC fluid inside of the conduit without leaving the exhaust duct. 
     
     
         5 . The system of  claim 1 , wherein the heat exchanger is one of a plate or plate-and-fin heat exchanger. 
     
     
         6 . A system for power generation using an Organic Rankine Cycle (ORC), the system comprising:
 a heat exchanger configured to be mounted inside a duct, the heat exchanger comprising:   an inlet which traverses from an outer side of the duct to an inner side of the duct and is configured to receive an ORC fluid;   an outlet which traverses from the inner side of the duct to the outer side of the duct and is configured to exit the ORC fluid; and   a conduit connecting the inlet to the outlet and configured to heat the ORC fluid,   wherein the heat exchanger is configured to operate in a near-critical region of the ORC fluid, and   wherein the near-critical region of the ORC fluid being is described by an upper half of a curve linking a triple point and a critical point for the ORC fluid, and the curve is defined by pressure values and temperature values which define boiling points for the ORC fluid.   
     
     
         7 . The system of  claim 6 , wherein the heat exchanger further comprises:
 a preheater section connected to the inlet and located towards a cooler end of the duct;   an evaporator section connected to the preheater section and located towards a warmer end of the duct, the evaporator section being configured to evaporate a pressurized liquid; and   a superheater section connected to the evaporator section and connected to the outlet, the superheater section being located between the preheater section and the evaporator section and the superheater section being configured to superheat a vapor from the evaporator section.   
     
     
         8 . The system of  claim 6 , wherein the near-critical region of the ORC fluid is described by an upper twenty percent of the curve linking the triple point and the critical point for the ORC fluid. 
     
     
         9 . A method for performing a heat exchange in a power generation system using an Organic Rankine Cycle (ORC) fluid, the method comprising:
 receiving at a heat exchanger heat from a source, wherein the heat exchanger is configured to be mounted entirely inside a duct, the heat exchanger having a single inlet, a conduit and a single outlet;   receiving the ORC fluid as a pressurized liquid at a pressure greater than or equal to a critical pressure of the ORC fluid at the single inlet which traverses from an outer side of the duct to an inner side of the duct;   exiting the ORC fluid in a supercritical phase at the single outlet which traverses from the inner side of the duct to the outer side of the duct; and   passing the ORC fluid through the conduit between the single inlet and the single outlet, the conduit being provided entirely inside the duct, while heating the ORC fluid to change from the pressurized liquid to the supercritical fluid,   wherein the heat exchanger is configured to heat the ORC fluid to a temperature greater than or equal to a critical temperature of the ORC fluid, and to exit the ORC fluid through the single outlet as a supercritical fluid, and   wherein the supercritical fluid is defined by the temperature being greater than the critical temperature and the pressure being greater than the critical pressure.   
     
     
         10 . A method for heating an Organic Rankine Cycle (ORC) fluid in a heat exchanger, the method comprising:
 receiving at a heat exchanger heat from a source, wherein the heat exchanger is configured to be mounted inside a duct and has an inlet, a conduit and an outlet;   receiving the ORC fluid as a pressurized liquid at the inlet which traverses from an outer side of the duct to an inner side of the duct;   exiting the ORC fluid in a near-critical region at the outlet which traverses from the inner side of the duct to the outer side of the duct, and   passing the ORC fluid through the conduit between the inlet and the outlet, the conduit being provided inside the duct, while heating the ORC fluid to change from the pressurized liquid to the near-critical region,   wherein the near-critical region of the ORC fluid is described by an upper half of a curve linking a triple point and a critical point for the ORC fluid, and   wherein the curve is defined by pressure values and temperature values which define boiling points for the ORC fluid.