1. Introduction
High temperature heat exchangers (HTHE) (arbitrarily meaning
temperatures above 650 C) is one of the most important components
to transfer thermal energy from one loop to another loop
in many highly efficient power and propulsion systems, such as
recuperative gas turbine and combined cycles, externally fired
cycles, recuperative microturbine systems and the new generation
reactors. In the high temperature gas-cooled reactors (HTGRs) indirect
system, it is used as an intermediate heat exchanger (IHX) to
transfer the heat from the primary helium from the core to a secondary
coolant, such as helium or nitrogen/helium mixture, for
electricity generation system or hydrogen production process.