Accession Number : ADA425961


Title :   A Mini-channel Heat Exchanger System for Heating, Boiling, and Superheating Water by Radiant Combustion


Descriptive Note : Technical rept. Mar 2002-Nov 2003


Corporate Author : AIR FORCE RESEARCH LAB TYNDALL AFB FL MATERIALS AND MANUFACTURING DIRECTORATE


Personal Author(s) : Sawyer, Mikel L ; Shaaban, Aly H ; Salavani, Reza


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a425961.pdf


Report Date : 15 Jun 2004


Pagination or Media Count : 10


Abstract : 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 gm/s 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 W/cm2 in the single-phase regions and 4.7 to 9.8 W/cm2 in the boiling region, based on the wetted wall area. The absorbed heat flux increased as coolant mass flux or Reynolds number increased.


Descriptors :   *HEAT EXCHANGERS , *STEAM GENERATORS , SUPERHEATING , HEAT FLUX , FUEL CELLS , REYNOLDS NUMBER , HEAT TRANSFER COEFFICIENTS , BOILING , EXHAUST GASES


Subject Categories : Electric Power Production and Distribution
      Air Condition, Heating, Lighting & Ventilating


Distribution Statement : APPROVED FOR PUBLIC RELEASE