ENHANCEMENT OF FLOW JET COMBINED BOILING HEAT TRANSFER OF FC 72 OVER MICRO PIN FINNED SURFACES
For highly efficient solving of the power dissipation problem of electronic components with high heat flux, experimental study of the flow jet combined boiling heat transfer on silicon chips was conducted. Micro pin fins with dimensions of 30x60 mm and 30x120 mm (thickness x height) were fabricated on the chip surfaces by the dry etching technique. The experiments were made at three different cross flow velocities Vc (0.5, 1.0, 1.5 m/s) and different jet velocities Vj (0 2 m/s) with two liquid subcooling Tsub (25*C and 35*C) A smooth surface was also tested for comparison. The micro pin fins showed a considerable heat transfer enhancement due to an increase in effective heat transfer surface area caused by micro convection around micro pin fins. The maximum allowable heat flux qmax is increased and the wall superheat is decreased greatly. For a given Vc, the heat transfer enhancement is more significant as Vj increases, but the qmax increment decreases as Vc increases. The fin efficiency decreases as Vc or/and Vj increases or the heat flux q increases. The maximum qmax can reach 161 W/cm at Vc 1.5 m/s, Vj 2 m/s, Tsub 35*C for chip PF30 120.