Method and apparatus for phase change driven actuator

Abstract

A phase change driven actuation device comprises an elongate combustion tube having: an inlet section, including an inlet for combustible material; an extinguishing section; and an ignition section, including an igniter displaced along a length of the tube from the inlet section to ignite the combustible material. A fluid is disposed adjacent an exterior surface of the elongate combustion tube and is configured to be heated by heat created by combustion of the combustible material and to at least partially undergo a phase change from a liquid state to a gaseous state upon combustion of the combustible material. At least one energy extraction device is in communication with the fluid to extract energy created by the phase change of the fluid.

1 . A phase change driven actuation device, comprising: 
 a) an elongate combustion tube having: 
 i) an inlet section, including an inlet for combustible material;  
 ii) an extinguishing section; and  
 iii) an ignition section, including an igniter displaced along a length of the tube from the inlet section to ignite the combustible material;  
   b) a fluid disposed adjacent an exterior surface of the elongate combustion tube, the fluid being configured to be heated by heat created by combustion of the combustible material and to at least partially undergo a phase change from a liquid state to a gaseous state upon combustion of the combustible material; and    c) at least one energy extraction device, in communication with the fluid to extract energy created by the phase change of the fluid.    
     
     
         2 . The device of  claim 1 , wherein at least a portion of each of the combustion tube and the energy extraction device are contained within a substantially pressure-tight system.  
     
     
         3 . The device of  claim 1 , wherein an exterior surface of the combustion tube includes surface irregularities configured to serve as nucleation sites at which the fluid begins undergoing the phase change from a liquid to a gaseous state.  
     
     
         4 . The device of  claim 1 , wherein the fluid comprises a substantially incompressible fluid.  
     
     
         5 . A phase change driven actuation device, comprising: 
 a) an elongate combustion tube having: 
 i) an inlet section, including an inlet for combustible material; and  
 ii) an ignition section, including an igniter displaced along a length of the tube from the inlet section to ignite the combustible material;  
   b) a first fluid, disposed adjacent at least a portion of an external surface of the combustion tube, the first fluid being configured to be heated by heat created by combustion of the combustible material and to at least partially undergoing a phase change from a liquid state to a gaseous state upon combustion of the combustible material;    c) a flexible shroud disposed adjacent at least a portion of the first fluid, the flexible shroud being configured to expand and contract in response to phase change undergone by the first fluid; and    d) a second fluid disposed adjacent an opposite side of the flexible shroud as the first fluid, the second fluid being configured to be pressurized by expansion and contraction of the flexible shroud to thereby extract energy from combustion of the combustible material.    
     
     
         6 . A method of extracting energy from combustible material, comprising the steps of: 
 a) combusting the combustible material within an elongate tube;    b) extracting heat formed by combustion of the combustible material with a substantially incompressible fluid, the fluid at least partially undergoing a phase change from a liquid state to a gaseous state upon combustion of the combustible material; and    c) extracting energy resulting in the incompressible fluid as a result of the phase change undergone by the fluid.