Bubble departure diameter at transient heat release

Flow Boiling on Micropin Fins Entrenched Inside a Microchannel—Flow Patterns and Bubble Departure Diameter and Bubble Frequency

Flow boiling of HFE 7000 in five parallel microchannels of 222 m hydraulic diameter, each containing a single row of 24 in-line 100 m pin fins, was investigated. High speed photography revealed the dominant flow patterns, namely, the bubbly flow, the multiple flow, and the wavy-annular flow. The interaction of the bubble with the pin fins during nucleate boiling from G 350 kg /m2 s to G 827 kg ...

Study of bubble growth in water pool boiling through synchronized, infrared thermometry and high-speed video

High-speed video and infrared thermometry were used to obtain timeand space-resolved information on bubble nucleation and heat transfer in pool boiling of water. The bubble departure diameter and frequency, growth and wait times, and nucleation site density were directly measured for a thin, electrically-heated, indium-tin-oxide surface, laid on a sapphire substrate. These data are very valuabl...

Prediction of bubble departure in forced convection boiling: A mechanistic

Two Phase Heat Transfer Characteristics in a Vertical Small Diameter Tube at Sub Atmospheric Pressure

Two-phase heat transfer is experimentally examined through vertical small diameter tubes, D =1.45 and 2.8 mm using water under a pressure of 50 to 81 kPa and a natural circulation condition. The pool boiling correlation by Stephan-Abdelsalam and the thermosyphon boiling correlation by Imura, et al. predict the measured experimental data in the 2.8 mm tube with an error of -30%. A large heat tra...

Mechanism and Prevention of Scale Formation in Boilers

Nucleate boiling heat transfer coefficients may be strongly reduced by scale formation, even for conditions where the bulk foulant concentration is well below the saturation concentration. Due to the mechanism of micro-layer evaporation, the local concentration at the heat transfer surface can be considerably increased, causing the formation of scale and changes in bubble frequency and bubble d...