Chapter 10 Boiling and Condensation10-70 A 40-cm long cylindrical heat pipe dissipates heat at a rate of 150 W. The diameter and mass of a 40-cm long copper rod that can conduct heat at the same rate are to be determined. AssumptionsSteady operating conditions exist.PropertiesThe properties of copper at room temperature are ρ= 2702 kg/m3and k= 237 W/m.°C.AnalysisThe rate of heat transfer through the aluminum rod can be expressed as &QkATL=ΔSolving for the cross-sectional area Aand the diameter Dgives 150 W ΔT= 4°C L= 40 cmHeat pipe D = 0.5 cm 150 W cm28.4===⎯→⎯==°°=Δ=π)cm9.632(444cm9.632m0.06329=W)150(C)C)(4W/m.(237m0.42222ADDAQTkLA&The mass of this aluminum rod is mVAL===ρρ(2702 kg / m )(0.06329 m )(0.4 m) =
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