Energy transfer in mechanical systems: During steady-state operation, a mechanical gearbox receives 70 KW of input power through
the input shaft and delivers power through the output shaft. Considering the gearbox as a thermodynamic system, the rate of convection heat transfer generated during its operation is defined by: where h 0.171 kW/m2-K is the convection heat transfer coefficient, A 1.0 m is the outer surface area of the gearbox, T 300 K is the temperature of the outer surface, and T 293 K is the temperature of the surrounding air. For the gearbox, evaluate the heat transfer rate, 2, and the power delivered through the output shaft, W.
1 answer:
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Answer:
1791 secs ≈ 29.85 minutes
Explanation:
( Initial temperature of slab ) T1 = 300° C
temperature of water ( Ts ) = 25°C
T2 ( final temp of slab ) = 50°C
distance between slab and water jet = 25 mm
<u>Determine how long it will take to reach T2</u>
First calculate the thermal diffusivity
∝ = 50 / ( 7800 * 480 ) = 1.34 * 10^-5 m^2/s
<u>next express Temp as a function of time </u>
T( 25 mm , t ) = 50°C
next calculate the time required for the slab to reach 50°C at a distance of 25mm
attached below is the remaining part of the detailed solution
