Resumen
This paper presents an experimental characterization of liquid nitrogen (LN2) flow boiling in additively manufactured minichannels. There is a pressing need of concerted efforts from the space exploration and thermal transport communities to design high-performance rocket engine cooling channels. A close observation of the literature gaps warrants a systematic cryogenic flow boiling characterization of asymmetrically heated small (<3 mm) non-circular channels fabricated with advanced manufacturing technologies at mass flux > 3000 kg/m2s and pressure > 1 MPa. As such, this work presents the LN2 flow boiling results for three asymmetrically heated additively manufactured GR-Cop42 channels of 1.8 mm, 2.3 mm, and 2.5 mm hydraulic diameters. Twenty different tests have been performed at mass flux~3805?14,295 kg/m2s, pressures~1.38 and 1.59 MPa, and subcooling~0 and 5 K. A maximum departure from nucleate boiling (DNB)-type critical heat flux (CHF) of 768 kW/m2 has been achieved for the 1.8 mm channel. The experimental results show that CHF increases with increasing LN2 flow rate (337?459 kW/m2 at 25?57 cm3/s for 2.3 mm channel) and decreasing channel size (307?768 kW/m2 for 2.5?1.8 mm channel). Finally, an experimental DNB correlation has been developed with 10.68% mean absolute error.