Heat transfer and pressure drop in a rotating two-pass square channel with different ribs at high rotation numbers

Rotation effects on heat transfer and pressure drop in a rotating two-pass square channel with ribs is experimentally investigated. The cooper plate heating technique is applied to obtain the regional average heat transfer coefficients. The Reynolds number and rotation number varies from 10000 to 60000, and 0 to 2.0, respectively. Rib turbulators are placed on the leading and trailing walls of the channel at an angle of 90 deg or 45 deg to the flow direction. The rib pitch-To-height (P/e) ratio is 10 and the height-To-hydraulic diameter (e/Dh) ratio is 0.1 for all tests. The detailed comparisons between smooth wall case and ribbed wall cases are presented. At stationary, increasing the Reynolds number decreases heat transfer and thermal performance ratios, but raises the friction factor ratios dramatically. Rotation shows the strongest effect on heat transfer in smooth case, and then 90 deg rib case, and the least in 45 deg rib case. Channel friction in smooth case is increased by rotation monotonously, but decreases with Ro in ribbed case when Ro increases up to 0.5. The similar thermal performances trends are observed for smooth and ribbed cases at rotation but with different peak point. The 45 deg rib channel has the superior thermal performance because it incurs the highest heat transfer and moderate pressure penalty.