Effects of Natural Convection and Radiation inside Hot-Gas-Duct on Temperature Distribution on the Surface

The VHTR necessarily requires an intermediate loop composed of a hot gas duct(HGD), an intermediate heat exchanger (IHX) and a process heat exchanger. The IHX is one of the important components of VHTR system because the IHX transfers the 950 .deg. high temperature massive heat to a hydrogen production plant or power conversion unit at high system pressure. Hot gas duct (HGD) is a unique component of a gas cooled reactor (GCR). The internal of a HGD is insulated using a ceramic fiber insulator (Kaowool) to prevent a mechanical failure itself from high temperature and high pressure operating conditions. The coolant temperature at the internal of a HGD can go up to 950 .deg. C. Thermo-hydraulic simulation using the COMSOL commercial solver is successfully performed at a uniform heat flux condition in a horizontal HGD. We obtained nonlinear temperature distribution from the COMSOL simulation with the assumption of the insulator in a HGD governed with conduction and convection heat transfer in porous medium