Numerical analysis of steady state and transient analysis of high temperature ceramic plate-fin heat exchanger

Abstract

In this study three-dimensional model of ceramic plate-fin high temperature heat exchanger with different fin designs and arrangements is analyzed numerically using ANSYS FLUENT and ANSYS structural module. The ability of ceramics to withstand high temperature and corrosion makes silicon carbide (SiC) suitable candidate material to be used in high temperature heat exchanger. The operating temperature of heat exchanger is 950°C and the operating pressure is 1.5MPa. The working fluids are helium, sulfur trioxide, sulfur dioxide, oxygen and the water vapor. Fluid flow and heat transfer analysis are carried out for steady and transient state in FLUENT. The obtained thermal and pressure load for the steady and transient state from ANSYS FLUENT are imported to ANSYS structural module to obtain the principal stress and the factor of safety. Different arrangements of rectangular fins, triangular fins, inverted bolt fins and ripsaw fins are studied. From the results it is found that the minimum stress and the maximum safety factor are obtained for inverted bolt fins. The triangular fins have the maximum principal stress and minimum factor of safety. However, the fluid flow and heat transfer analysis show inverted bolt fins and triangular fins produce higher pressure drop and friction factor. The steady state maximum principal stress is 10.08MPa, 9.90MPa and 11.43MPa for straight, staggered and top and bottom ripsaw fin arrangement. The corresponding safety factors are 21.80, 21.95 and 19.01, respectively. The ripsaw fin design is chosen to be the best design since it gives less stress, more safety factor, less pressure drop, friction factor and reasonable heat transfer rate. From the results it is also found that thermal stress is more significant than the mechanical stress.