Thermo A constant volume duct operating at atmospheric pressure with one exit se

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Thermo

A constant volume duct operating at atmospheric pressure with one exit sees two inlet flows; one entering at 0.8 kg/s @ 317 K with an entropy of 1.7574 kJ/(kgK) and the other entering at 1.23 kg/s @ 321 K with an entropy of 1.7700 kJ/(kgK). Heat transfer at a rate of 75.3 kW from a reservoir at 300 K is used to heat the duct. If the working fluid is air acting as an ideal gas, at steady state calculate:

a) The exit flow rate in [kg/s]

b) The exit temperature in [K]; note the entropy exiting has a value of 1.8748 kJ/(kgK), but you do not need it for this part.

c) The entropy generation in [kW/K]; note if this process can or cannot occur. If it cannot occur, indicate the minimum reservoir temperature in [K] that is required.

Assume uniform properties entering and exiting, KE and PE are negligible, and heat transfer at the boundary is uniform.

Show all unit conversions and calculations.

Explanation / Answer

temperature T1=317k

entropy S1 = 1.7574 KJ/KGK

volume V1=0.8kg/s

volume V2=1.23kg/s

temperature T2=321k

entropy S2=1.7700KJ/KGK

heat transfer Q= 75.3KW

resrvoir temp is =300K

exit flow rate is

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