Patents by Inventor Stephen U. S. Choi

Stephen U. S. Choi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7998309
    Abstract: A one step method and system for producing nanofluids by a nanoparticle-source evaporation and deposition of the evaporant into a base fluid. The base fluid such oil or ethylene glycol is placed in a rotating cylindrical drum having an adjustable heater-boat-evaporator and heat exchanger-cooler apparatus. As the drum rotates, a thin liquid layer is formed on the inside surface of the drum. An insulated heater-boat-evaporator having an evaporant material (nanoparticle-source) placed within its boat evaporator is adjustably positioned near a portion of the rotating thin liquid layer, the evaporant material being heated thereby evaporating a portion of the evaporant material and forming nanoparticles, the nanoparticles absorbed by the liquid film to form nanofluid.
    Type: Grant
    Filed: March 23, 2010
    Date of Patent: August 16, 2011
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: Milivoje Kostic, Mihajlo Golubovic, John Hull, Stephen U. S. Choi
  • Patent number: 7718033
    Abstract: A one step method and system for producing nanofluids by a particle-source evaporation and deposition of the evaporant into a base fluid. The base fluid such (i.e. ethylene glycol) is placed in a rotating cylindrical drum having an adjustable heater-boat-evaporator and heat exchanger-cooler apparatus. As the drum rotates, a thin liquid layer is formed on the inside surface of the drum. A heater-boat-evaporator having an evaporant material (particle-source) placed within its boat evaporator is adjustably positioned near a portion of the rotating thin liquid layer, the evaporant material being heated thereby evaporating a portion of the evaporant material, the evaporated material absorbed by the liquid film to form nanofluid.
    Type: Grant
    Filed: July 12, 2006
    Date of Patent: May 18, 2010
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: Milivoje Kostic, Mihajlo Golubovic, John R. Hull, Stephen U. S. Choi
  • Patent number: 6221275
    Abstract: This invention is directed to a method of and apparatus for enhancing heat transfer in fluids such as deionized water. ethylene glycol, or oil by dispersing nanocrystalline particles of substances such as copper, copper oxide, aluminum oxide, or the like in the fluids. Nanocrystalline particles are produced and dispersed in the fluid by heating the substance to be dispersed in a vacuum while passing a thin film of the fluid near the heated substance. The fluid is cooled to control its vapor pressure.
    Type: Grant
    Filed: November 24, 1998
    Date of Patent: April 24, 2001
    Assignee: University of Chicago
    Inventors: Stephen U. S. Choi, Jeffrey A. Eastman