The onset of flow instability in uniformly heated horizontal microchannels

Onset of nucleate boiling and onset of flow instability in uniformly heated microchannels with subcooled water flow were experimentally investigated u sing 22-cm long tubular test sections, 1.17 mm and 1.45 mm in diameter, wit h a 16-cm long heated length. important experimental parameter ranges were: 3.44 to 10.34 bar channel exit pressure; 800 to 4500 kg/m(2)s mass flux (1 to 5 m/s inlet velocity): 0 to 4.0 MW/m(2) channel wall heat flux; and 744 0-33,000 Peclet number at the onset of flow instability. Demand curves (pre ssure drop versus mass flow rate curves for fixed wall heat flux and channe l exit pressure) were generated for the test sections, and were utilized fo r the specification of the onset of nucleate boiling and the onset of flow instability points. The obtained onset of nucleate boiling and onset of flo w instability data are presented and compared with relevant widely used cor relations.