Pressure drop and heat transfer performance in a rotating two-pass channel with staggered 45-deg ribs

The results show that the 45-deg ribs bring 40-80% higher heat transfer for ribbed walls and 15-65% for smooth walls. The rib-to-smooth Nu ratio declines with Reynolds number and is more sensible in the second passage. Meanwhile, 150-210% higher pressure drop in ribbed channel is observed compared to smooth one, but this penalty decreases with Reynolds number. Rotation presents more dominant influences on pressure drop in heated channel than unheated one. But rotation-to-stationary friction factors decrease with rotation number for both heated and unheated channel as Ro < 0.55, after which an increase trend is observed. The presence of buoyancy effect in heated channel helps to promotes rotational pressure drop variation. Also, ribbed-to-smooth thermal performance is significantly elevated by rotation when rotation number reaches over 0.25. The surface averaged heat transfer coefficients are developed with respect to buoyancy parameters.