heat exchanger

heat sink

flow boiling

boiling heat transfer

pool boiling

microchannel heat

boiling heat

heat transfer performance

spacer grid

Applied Thermal Engineering

• Sinusoidal wavy microchannels with secondary channels (SWSC) are designed and fabricated. • A complete high-speed measurement system are performed for flow boiling. • Flow boiling performance of SWSC are investigated and compared with the conventional rectangular microchannels (R). • Improvement in heat transfer performance are achieved by the SWSC microchannels. • Pressure drop and flow boiling instabilities are illustrated. Sinusoidal wavy microchannels with secondary channels (SWSC) are developed to integrate advantages of the sinusoidal corrugated structure and the introduction of secondary channels in flow boiling enhancement. Flow boiling investigations of acetone are made with variation in the heat flux and mass flux range of 251–512 kg/(m 2 ·s). The boiling curves, heat transfer coefficients, pressure drops and flow boiling instabilities are systematically investigated. The experimental results show that the SWSC microchannels can achieve better heat removal performance than the conventional rectangular microchannels (R). Besides, the premature ONB and delayed CHF can also be obtained. The increased density of bubble nucleation induced by the enlarged surface area and the liquid stored in the corner regions in the nucleate boiling dominated regime, as well as the continuously developing thin liquid film created by the introduction of secondary channels in the stable liquid film evaporation dominated regime are considered to be the main reasons for the notable enhancement in heat transfer. However, the SWSC microchannels suffer a higher pressure drop penalty. The pressure fluctuations and temperature fluctuations of the SWSC microchannels are also illustrated.

Experimental investigation of flow boiling performance in sinusoidal wavy microchannels with secondary channels