Effect of Running Parameters on Flow Boiling Instabilities in Microchannels

Area of Science:

• Heat Transfer
• Fluid Dynamics
• Microscale Engineering

Background:

• Flow boiling instability (FBI) in microchannels can cause mechanical vibrations and disrupt heat transfer.
• Understanding these instabilities is crucial for reliable microchannel heat sink performance.

Purpose of the Study:

• To experimentally investigate the effects of heat flux, microchannel length, and mass flux on flow boiling instability.
• To analyze pressure drop and temperature variations under different operating conditions.

Main Methods:

• Utilized a synchronous optical visualization experimental system.
• Employed pure acetone as the working fluid in a parallel triangle silicon microchannel heat sink.
• Systematically varied heat flux, heater length, and mass flux to record pressure drops and surface temperatures.

Main Results:

• Identified heat flux, heater length, and mass flux as key parameters influencing boiling instability.
• Observed earlier boiling incipience (TBI) and critical heat flux (CHF) at lower mass flux or longer heater lengths.
• Found pressure drops increased sharply in the two-phase region with increasing heat flux, leading to more pronounced instabilities.

Conclusions:

• Heat flux, microchannel length, and mass flux are critical factors determining flow boiling instability.
• Optimizing these parameters is essential for mitigating undesirable vibrations and maintaining stable heat transfer in microchannels.