Sunday, October 25, 2009

thermodynamics old jntu question papers

Code No: R05310803 Set No. 3
III B.Tech I Semester Regular Examinations, November 2007
(Chemical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. Water and a liquid mixture of propane and butane are admitted into a vaporizer at
50 oC and leave as vapors at 175 oC. The hourly 25 kg water, 350 kg propane and
550 kg of butane are admitted. Estimate the heat requirement in the vaporizer.
Component Latent heat of vaporization Boiling point a b×103 C×106
cal/gm mole at 100oC temp Tc
Propane 5038 96.6 8.41 35.95 -6.97
Butane 6138 151.8 2.25 45.40 -8.83
Water 10388 96.6 7.14 2.64 0.046
Cp =a+bT+cT2 where Cp is in cal/mol.k and T is in K. Mention the assumption
made to solve the problem. [16]
2. Carbon monoxide gas is burned at constant pressure with 100% excess air. The
reactants enter at 25 0C and the exhaust gases leave the reaction chamber at 1200
0C Estimate the heat loss from the reaction chamber
Standard heat of combustion of CO=-282,900 J/mol
Cp =a+bT+cT2 Cp in J/mol-K, T in K
The constants of a, b, c are: [16]
a b×103 c×106
CO2 26.75 42.26 -14.25
N2 27.02 5.81 -0.29
O2 25.29 13.25 -4.20
3. (a) Derive an expression for estimating fugacity of a liquid at a given T and P.
(b) The partial molar volume of methanol in methanol- water. Solution at x1 =
0.3881 (mole fraction) is 39.176 × 10 −6 m3/mol. The density of the mixture
is 905.376 kg/m3. Calculate the partial molar volume of water in the solution.
4. Derive and discuss the Wilson equation as a model of solution behaviour for mul-
ticomponent system. Discuss the merits of this model over others. Explain its
temperature dependence also. [16]
5. (a) Explain bubble print and dewprint.
(b) Describe the vapor/ liquid equilibrium calculation procedure for DEW P. Va-
por and liquid phases may be considered as non- ideal. [6+10]
Code No: R05310803 Set No. 3
6. When the compressibility factor Z is a function of P, T show that the residual
entropy of fluids from virial equation of state is SR
R = −
dT . [16]
7. Discuss about LLE and draw its solubility diagrams represented in the form of an
‘island’ [16]
8. In a laboratory investigation, acetylene is catalytically hydrogenated to ethylene at
1,1200C And 1 bar. If the feed is an equimolar mixture of acetylene and hydrogen,
what is the composition of the product stream at equilibrium? The reactions are
C2H2 ! 2C + H2
2C + 2H
K1= 4x105, K2 =2.5x10−6. [16]

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