A Mini-channel Heat Exchanger System for Heating, Boiling, and Superheating Water by Radiant Combustion
Technical rept. Mar 2002-Nov 2003
AIR FORCE RESEARCH LAB TYNDALL AFB FL MATERIALS AND MANUFACTURING DIRECTORATE
Pagination or Media Count:
A mini-channel steam generator was developed for a fuel reformer to convert jet to a hydrogen-rich stream for a 10 kW fuel cell. Exhaust gases produced saturated liquid in its first section. The second section surrounded a radiant burner. The system heated 1.2 to 2.6 gms of water to more than 650 deg C at exit pressures from 106 to 240 kPa, as required. The mini-channel system operated across three regimes liquid heating, boiling, and superheating. At certain locations, the number of the parallel channels was increased changed to restrain the total pressure drop. The channel hydraulic diameter was 0.14 Cm. The Reynolds number for the water ranged from 620 to 1,260 in the boiling section and from 1,260 to 3,140 in the superheating section, based on averaged fluid properties. The water absorbed heat fluxes ranging from 0.3 to 1.2 Wcm2 in the single-phase regions and 4.7 to 9.8 Wcm2 in the boiling region, based on the wetted wall area. The absorbed heat flux increased as coolant mass flux or Reynolds number increased.
- Electric Power Production and Distribution
- Air Conditioning, Heating, Lighting and Ventilating