The flow and heat transfer enhancement of a pair of embedded longitudinal vortices in narrow-channel are studied experimentally.

Based on the present model,the theoreti- cal calculation was performed to predict the flow characteristics for the developed flow in narrow annuli with the gap sizes of 1.

Numerical research was carried out on the convection heat transfer characteristics(in bilaterally)heated narrow annuli under the conditions of fully developed flow,where the inner and outer walls were heated by uniform but unequal heat fluxes.