Critical heat flux enhancement by means of liquid subcooling and centrifugal force induced by flow curvature

Experiments are performed to assess the feasibility of cooling high flux heat sources flush mounted on the inner wall of a cylindrical vessel by a dielectric liquid flowing at high velocity parallel to the vessel wall. Fluid motion is induced by rotating a stirrer having radial blades about the axis of the vessel. The study focusses on examining critical heat flux (CHF) enhancement attributed to liquid subcooling and the centrifugal body force induced by fluid rotation. This includes using test vessels with different inner radii, 4.19 and 7.62 cm, three heater lengths, 1.27,2.54 and 5.08 cm, and stirrers having two or four blades. CHF is found to be independent of heater length and the number of stirrer blades. CHF enhancement is achieved by increasing the liquid fill volume, increasing the rotational speed and/or decreasing the radius of curvature. The system facilitates the removal of heat at nearly isothermal wall conditions over a wide range of heat fluxes. A CHF correlation is presented which accounts for the effects of subcooling and centrifugal force over all conditions tested.