Engineering, 20.09.2020 09:01 tonio638

A 50 mm × 45 mm × 20 mm cell phone charger has a surface temperature of Ts = 33°C when plugged into an electrical wall outlet but not in use. The surface of the charger is of emissivity ε = 0.92 and is subject to a free convection heat transfer coeffcient of h = 4.5 W/m2 ⋅K. The room air and wall temperatures are T[infinity] = 22°C and Tsur = 20°C, respectively. If electricity costs C = $0.18/kW ⋅ h, determine the daily cost of leaving the charger plugged in when not in use.

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A 50 mm × 45 mm × 20 mm cell phone charger has a surface temperature of Ts = 33°C when plugged into...