ME354 Thermodynamics 2

Problem Set #2: Ideal Gases

Problem 2: 8-1

Starting with Gibbs equation, show that for a perfect gas undergoing an isentropic process (T2/ T1) = (P2/ P1)(k-1)/k, where k = cp/cv.

Solution

(28.6 KBytes)

Problem 2: 8-18

Find the enthalpy of liquid water for: a) saturated liquid at 150 oC, b) subcooled liquid at 150 oC and 1.7 MPa, and c) subcooled liquid at 150 oC and 24 MPa.

Answer: a) h_f = 632.2 kJ/kg, b) h = 633.5 kJ/kg, c) h = 657.8 kJ/kg

Solution

(43.9 KBytes)

Problem 2: 8-26

Argon is compressed isothermally from 100 oC at 1 atm to 4 atm. Calculate the final temperature and the work required per kg of flow. Compare this to an isentropic compression from the same inlet conditions to the same final pressure.

Answer:

isothermal:	Tf= 373.2 K,	W/m = 107.6 kJ/kg
isentropic:	Tf= 647.6 K,	W/m = 143.6 kJ/kg

Solution

(55.8 KBytes)

Problem 2: 8-58

Steam is throttled through an adiabatic valve from an inlet state of 1000 psia, 850 oF, to an exit pressure of 300 psia. Find the exit state using the generalized enthalpy chart and compare with results from the Mollier chart.

Answer:

generalized enthalpy:	T2= 791.3 oF
Mollier diagram:	T2= 790. oF
steam tables:	T2= 794.9 oF

Solution

(50.5 KBytes)

Problem 2: 5

Nitrogen at 6.4 MPa and 145 K is contained in a tank of 0.3 cubic meters. Heat is transferred to the nitrogen until the temperature is 190 K. Determine the heat transferred and the final pressure. Note: the definition of v/vcrit is in the table heading of Figure B.14a on page 616 of Reynolds & Perkins. a) using generalized charts b) assuming perfect gas and constant specific heats

Answer:

a) Q = 3592.7 kJ, Pf = 13.594 MPa

b) Q = 1493.7 kJ, Pf = 8.386 MPa

Solution

(61.3 KBytes)

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