Waste heat recovery and conversion system and related methods

Abstract

Various embodiments of a waste heat recovery and conversion system are disclosed. In one exemplary embodiment, the waste heat recovery system may include a heat exchanger for transferring heat from a first fluid to a second fluid and a power conversion unit configured to convert the energy transferred from the first fluid to the second fluid into usable energy. The heat exchanger may include an outer duct defining an inlet and an outlet through which the first fluid flows in and out, respectively, of the outer duct. The heat exchanger may also include an inner duct disposed inside the outer duct and defining an inner channel inside the inner duct and an outer channel between an outer surface of the inner duct and an inner surface of the outer duct. The inner duct may define an internal flow channel through which the second fluid flows to exchange heat energy with the first fluid.

1 . A heat exchanger comprising:
 an outer duct defining an inlet and an outlet through which a first fluid flows in and out, respectively, of the outer duct; and   an inner duct disposed inside the outer duct and defining an inner channel inside the inner duct and an outer channel between an outer surface of the inner duct and an inner surface of the outer duct;   wherein the inner duct defines an internal flow channel through which a second fluid flows to exchange heat energy with the first fluid.   
     
     
         2 . The heat exchanger of  claim 1 , wherein the first fluid flows in a first direction inside the outer duct, and the second fluid flows in a second direction substantially opposite to the first direction. 
     
     
         3 . The heat exchanger of  claim 1 , wherein both the outer duct and inner duct are substantially cylindrical. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the outer duct and inner duct are substantially concentric. 
     
     
         5 . The heat exchanger of  claim 1 , wherein the inner duct comprises a plurality of inner ducts disposed inside the outer duct. 
     
     
         6 . The heat exchanger of  claim 1 , further comprising a plurality of fins extending from the internal flow channel to either the inner channel or outer channel to enhance heat transfer between the first fluid and the second fluid. 
     
     
         7 . The heat exchanger of  claim 1 , wherein the second fluid enters the internal flow channel of the inner duct in a subcooled state and exits the internal flow channel in a superheated state. 
     
     
         8 . A waste heat recovery system comprising:
 a heat exchanger comprising:   an outer duct defining an inlet and an outlet through which a first fluid flows in and out, respectively, of the outer duct; and   an inner duct disposed inside the outer duct and defining an inner channel inside the inner duct and an outer channel between an outer surface of the inner duct and an inner surface of the outer duct;   wherein the inner duct defines an internal flow channel through which a second fluid flows to exchange heat energy with the first fluid; and   a power conversion unit configured to convert the energy transferred from the first fluid to the second fluid into usable energy.   
     
     
         9 . The system of  claim 8 , further comprising a condenser configured to condense the first fluid. 
     
     
         10 . The system of  claim 8 , further comprising a preheating interface disposed between a heat source and the heat exchanger, wherein the preheating interface is configured to preheat the second fluid prior to entering the heat exchanger. 
     
     
         11 . The system of  claim 10 , wherein the preheating interface comprises a preheating heat exchanger comprising:
 an inlet through which the first fluid enters to the preheating heat exchanger from the heat source;   an outlet through which the first fluid exits the preheating heat exchanger and enters the heat exchanger; and   a preheating channel through which the second fluid flows to preheat the second fluid prior to entering the heat exchanger.   
     
     
         12 . The system of  claim 10 , wherein the preheating interface comprises a flange configured to fix the preheating heat exchanger to the heat source. 
     
     
         13 . The system of  claim 10 , wherein the preheating interface comprises a flexible member configured to reduce vibration stress between the heat source and the heat exchanger.