Nitrogen gas flows into a convergent nozzle at a pressure of 225kPa, a temperatu

Question

Nitrogen gas flows into a convergent nozzle at a pressure of 225kPa, a temperature of 440K and with a very low inlet velocity which may be assumed to be zero. The flow is accelerated and exits the nozzle at a pressure of 100kPa and a temperature of 330K.

Assuming the nozzle is insulated, with no change in height between inlet and exit,

a) What is the change in specific enthalpy of the Nitrogen ? ( ) kJ/kg

b) What is the velocity of the Nitrogen at the exit of the nozzle ? ( ) m/s

Assume a constant specific heat of N2 at constant pressure, CpN2 = 1042 J/kg K

What is the thermal efficiency of a Carnot cycle heat engine operating between a hot reservoir at 350oC and a cold reservoir at 18oC ? ( ) (as %)

Please SHOW WORK

Explanation / Answer

V^2=2(h1-h2)=2CpN2(T1-T2)=2*1042*(440-330)=229.24*1000 or,V=478.79m/s Change in specific enthalpy=h2-h1=-114.62kJ/kg The thermal efficiency of the Carnot heat engine=1-Tl/Th=1-291/623=0.5329=53.29%

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.