An electric motor operating at steady state draws a current of 10 amp with a voltage of 220 V. The output shaft rotates at 1000 RPM with a torque of 16 N-m applied to an external load.
The rate of heat transfer from the motor to its surroundings is related to the surface temperature $T_o$ and the ambient temperature $T_b$ by $hA(T_o - T_b)$, where $h = 100 \text{W/m}^2 \text{-K}$, $A = 0.195$
m$^2$, and $T_b = 293$ K. Energy transfers are considered positive in the directions indicated by the arrows on Fig. P6.59.
(a) Determine the temperature $T_o$ in K.
(b) For the motor as the system, determine the rate of entropy production, in kW/K.
(c) If the system boundary is located to take in enough of the nearby surroundings for heat transfer to take place at temperature $T_b$ determine the rate of entropy production, in kW/K,
for the enlarged system.
Determine the power provided to the motor, in kW.
$W_{elec}$ =
kW
exact number, no tolerance
Determine the shaft power from the motor, in kW.
$W_{shaft} = \dot{W}_{shaft} = $
kW
the tolerance is +/-2%
GO Problem: Part 4
Determine the rate of entropy production for this system, in kW/K.
$\dot{\sigma} = $
kW/K
the tolerance is +/-2%
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GO Problem: Part 5
Determine the rate of entropy production for this system including the nearby surroundings, in kW/K.
$\dot{\sigma} = $
kW/K
the tolerance is +/-2%
