수소 생산을 위한 동축원통형 수증기 개질기의 성능 및 열유속에 대한 수치해석 연구Numerical Study on the Performance and the Heat Flux of a Coaxial Cylindrical Steam Reformer for Hydrogen Production
Heat transfer rate is a very important factor for the performance of a steam reformer because a steam
reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can
improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam
reformer are studied in this paper using numerical method under various operating conditions. Langmuir-
Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction.
Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS)
reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses
33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and
its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at
coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of
cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the
inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the
temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is
increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since
an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel
conversion is decreased because of the heat transfer limitation and short residence time.