Experimental investigation of critical heat flux in microchannels for flow-field probes

Critical heat flux (CHF) of water in circular stainless steel microchannels with inner diameters from ~127 μm to ~254 μm and outer diameter from ~254 μm to ~508 μm was investigated. Forty-seven CHF data points were acquired over mass velocities ranging from 1,200 to 53,000 kg/m2s, heated lengths from 2 cm to 8 cm, and inlet exit qualities from -0.2 to 0.44. Most of the exit qualities fell below 0.1. It was found that CHF conditions were more dependent on mass velocity and heated length than on exit thermal condition. The results were also compared to six CHF correlations with a mean average error ranging from 22% to 261.8%. A new correlation was proposed to better predict the critical heat flux data under the thermal-hydraulic conditions studied in this investigation.