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(2) 50 kg of a certain gas is contained within the piston-cylinder assembly The

ID: 703511 • Letter: #

Question

(2) 50 kg of a certain gas is contained within the piston-cylinder assembly The gas undergoes a process which the is PVconstant (-1.5) The given conditions as follows; pl-6 bars,vl-0.2 cubic meters, v2-0.4 cubic meters, the change of internal energ-10.5 kJ kg. (Hints KE-PE-0, bar-100,000 N sq.m, 1J-1000 N.m. W-((plvI)ln( 2v1) or Wip2v2- plvi)(a-n) (a) Find P2 in bars (b) Find the Work in kJ for n-1.5 (c) Find the net heat transfer for the process, in kJ (3) Which of the following is a standard cycle of steam turbine? (a)Rankine cycle(b) Carnot cycle(c)Brayton cycled)Otto cycle (4) For MSU power plant visit field trip, List(a) the steam flow rate of main campus in poundshr: ( (b) Boiler Exit Temperature in K: (

Explanation / Answer

Ans 2

Part a

In adiabatic reversible process

P1V1n = P2V2n

6 x 0.21.5 = P2 x 0.41.5

P2 = 6 x (0.2/0.4)1.5 = 6 x 0.51.5

= 2.12 bar

Part b

Work

W = (P2V2 - P1V1) / (1-n)

= [(2.12*0.4) - (6*0.2)] / (1-1.5)

= - 0.352/-0.5

= 0.704 bar-m3 x 10^5Pa/bar x 1kPa/1000 Pa

= 70.4 kJ

Part C

From the first law of thermodynamics

dU = dQ + dW

dQ = dU - dW

= 10.5 kJ/kg x 50 kg - 70.4 kJ

= 454.6 kJ