A direct mixing type axial flow cyclone heat exchanger between gas and high temperature particles is proposed which serves as particle separator as well and its heat transfer performance was examined both experimentally and numerically. In this heat exchanger, the particles, after being mixed directly with gas, transfer their heat to the gas in the form of quasi-counter-flow and are effectively re-separated by centrifugal force due to swirling motion of the gas. The following results were obtained from the experiments by using the mock-up apparatus: high heat transfer performance was achieved by mounting a particle diffuser just below the particles' feeding nozzle in order to promote the dispersion of particles in the vessel. Furthermore, by investigating the effect of the location of particles' feeding nozzle on the heat transfer performance, the case when the nozzle was flush with the gas inlet was concluded to be most suitable.
