Question

At a particular instant of time, a square metal bar has an axial temperature distribution given by:

T(x) = 50(1+ 8x2

) where x is the distance (in meters) measured from one end and T is the local

temperature (in °C). Due to its high thermal conductivity, the temperature in the bar may be

assumed uniform at any cross-section. The cross-section of the bar has width W = 2.5 cm and the

length of the bar is L = 0.3 m. The density and specific heat of the metal are ρ = 2700 kg/m3and

c = 0.90 J/kg-K, respectively.

a.) Is the average bar temperature rising or falling at this instant of time? (Assume that the bar

can only transfer energy at its end points; i.e., the sides are insulated.)
b.) Calculate the change in internal energy if the bar is cooled to a uniform temperature of Tf =

20°C.

c.) Calculate the change in entropy of the bar for the process in part (b).

d.) What is the change in exergy of the bar for the process in part (b) given a large heat sink at

20°C?

e.) What is the maximum thermal efficiency at which work could be produced for the conditions

in part (d)?​

Answer 1

Answer:

don't know the answer sorry

Answer 2

Answer:

Explain

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