Search for dissertations about: "critical diameter"

Showing result 1 - 5 of 69 swedish dissertations containing the words critical diameter.

2. 1. Some two-phase flow and boiling heat transfer characteristics in small diameter tubes

   Author : Sheng ChungHong; KTH; []
   Keywords : Two-phase flow; Heat transfer; Microscale; Small diameter tube; Bubble shape; Bubble velocity; Critical diameter for bubble rising; Film thickness; Visualisation; Boiling flow pattern;

   Abstract : .... READ MORE

4. 2. Air-pocket transport in conjunction with bottom-outlet conduits for dams

   Author : Ting Liu; Anders Wörman; James Yang; Staffan Lundström; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Air-water two-phase flow; critical velocity; diameter effect; roughness; VOF model; bottom outlet; experiment;

   Abstract : Undesired air entrainment in bottom outlet conduits of dams may cause pressure transients, leading to conduit vibrations, blowback, discharge pulsation and even cavitation, and jeopardize the operational safety. Due to design limitations or construction costs, it is impossible to create an air free environment in a pressurized pipe. READ MORE

5. 3. Modelling air―water flows in bottom outlets of dams

   Author : Ting Liu; James Yang; Anders Wörman; Michael Pfister; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Air pocket; Air entrainment; Bottom outlet; Critical velocity; Critical submergence; CFD; Experiment; Vortex; PIV; Two-phase air―water flow; Mark- och vattenteknik; Land and Water Resources Engineering; Civil and Architectural Engineering; Byggvetenskap;

   Abstract : If air is entrained in a bottom outlet of a dam in an uncontrolled way, the resulting air pockets may cause problems such as blowback, blowout and loss of discharge capacity. In order to provide guidance for bottom outlet design and operation, this study examines how governing parameters affect air entrainment, air-pocket transport and de-aeration and the surrounding flow structure in pipe flows. READ MORE

6. 4. An Experimental Study on Micro-Hydrodynamics of Evaporating/Boiling Liquid Film

   Author : Shengjie Gong; Ma Weimin; Horst-Michael Prasser; KTH; []
   Keywords : liquid film; critical thickness; boiling; critical heat flux; rupture; dry spot; confocal optical sensor; SRA - Energy; SRA - Energi;

   Abstract : Study of liquid film dynamics is of significant importance to the understanding and control of various industrial processes that involve spray cooling (condensation), heating (boiling), coating, cleaning and lubrication. For instance, the critical heat flux (CHF) of boiling heat transfer is one of the key parameters ensuring the efficiency and safety of nuclear power plants under both operational and accident conditions, which occurs as the liquid layers (microlayer and macrolayer) near the heater wall lose their integrity. READ MORE

7. 5. Flow Boiling Heat Transfer in Single Vertical Channels of Small Diameter

   Author : Claudi Martin Callizo; Björn Palm; Predrag Hrnjak; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; microchannel; heat exchanger; heat transfer; flow boiling; flow patterns; onset of nucleate boiling; dryout; critical heat flux; Mechanical and thermal engineering; Mekanisk och termisk energiteknik;

   Abstract : Microchannel heat exchangers present many advantages, such as reduced size, high thermal efficiency and low fluid inventory; and are increasingly being used for heat transfer in a wide variety of applications including heat pumps, automotive air conditioners and for cooling of electronics.However, the fundamentals of fluid flow and heat transfer in microscalegeometries are not yet fully understood. READ MORE