A technique for cooling a multichip module involves submerging the module in a saturated fluorocarbon liquid. Vapor generated due to boiling at the module surface is condensed on the outer surface of copper tubing suspended in the vapor space above the liquid. The thin-waned tubing is of diameter D = 10 mm and is coiled in a horizontal plane. It is cooled by water that enters at 285 K and leaves at 315 K. All the heat dissipated by the chips within the module is transferred from a 100-mm by 100-mm boiling surface, at which the flux is 10⁵ W/m² , to the fluorocarbon liquid, which is at T_sat = 57°C, Liquid properties are k l = 0.0537 W/m ∙ K, _Cp1 = 1100 J/kg ∙ K, h_fg ≈ h_fg = 84,400 J/kg, p₁ = 1619.2 kg/m³, P_v = 13.4 kg/m³, σ = 8.1 x 10^-3 kg/s² , μ₁ = 440 x 10^-6 kg/m ∙ s, and Pr₁ = 9.

(a) For the prescribed heat dissipation, what is the required condensation rate (kg/s) and water flow rate (kg/s)?

(b) Assuming fully developed flow throughout the tube, determine the tube surface temperature at the coil inlet and outlet.

(c) Assuming a uniform tube surface temperature of Ts = 53.0°C, determine the required length of the coil.

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Water Condenser coil Fluorocarbon vapor and liquid, Tast Multichip module