A passive technique for cooling heat-dissipating

Chapter 10, Problem 10.72

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A passive technique for cooling heat-dissipating integrated circuits involves submerging the ICs in a lowboiling point dielectric fluid. Vapor generated incooling the circuits is condensed on vertical platessuspended in the vapor cavity above the liquid. Thetemperature of the plates is maintained below the saturation temperature, and during steady-state opera-tion a balance is established between the rate of heattransfer to the condenser plates and the rate of heatdissipation by the ICs.Consider conditions for which the 25-mm2surface areaof each IC is submerged in a fluorocarbon liquid forwhich Tsat?50?C, ?l?1700 kg/m3, cp,l?1005 J/kg?K,?l?6.80?10?4kg/s?m, kl?0.062 W/m?K, Prl?11.0, ??0.013 N/m, hfg?1.05?105J/kg, Cs,f?0.004, and n?1.7. If the integrated circuits areoperated at a surface temperature of Ts?75?C, whatis the rate at which heat is dissipated by each circuit?If the condenser plates are of height H?50 mm andare maintained at a temperature of Tc?15?C by aninternal coolant, how much condenser surface areamust be provided to balance the heat generated by 500integrated circuits?