Download PTU B.Tech 2021 Jan Food-Technology 3rd Sem 78734 Thermodynamics Question Paper

Roll No. Total No. of Pages : 02

Total No. of Questions : 18

B.Tech. (Food Technology) (Sem.-3)

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THERMODYNAMICS

Subject Code: BTFT-217-19

M.Code : 78734

Time: 3 Hrs. Max. Marks : 60

INSTRUCTIONS TO CANDIDATES :

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1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.

SECTION-A

1. Define a thermodynamic system.

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2. Draw a p-T (pressure-temperature) diagram for a pure substance.
3. Does wet steam obey laws of perfect gases ?
4. Explain clearly the difference between a non-flow and a steady flow process.
5. Why only in constant pressure non-flow process, the enthalpy change is equal to heat transfer?
6. What do you mean by "Thermodynamic temperature"?

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7. What are the characteristics of entropy?
8. What is the difference between an ideal and a perfect gas?
9. What is Joule-Thomson coefficient?
10. Explain the importance of Maxwell relations in thermodynamics.

SECTION-B

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1. Derive the following relations :
   1. \( u=a-T\left(\frac{\partial a}{\partial T}\right)_p \)
   2. \( h=g-T\left(\frac{\partial g}{\partial T}\right)_p \)

   Where a = Helmholtz function (per unit mass), and

   g = Gibbs function (per unit mass).

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12. Derive the relationship between the two principal specific heats and characteristic gas constant for a perfect gas.
13. Prove that all reversible engines operating between the same heat reservoirs have the same efficiency.
14. Determine the entropy change of 4kg of a perfect gas whose temperature varies from 127°C to 227°C during a constant volume process. The specific heat varies linearly with absolute temperature and is represented by the relation :
    \( C_v = (0.48 + 0.0096 \text{ T}) \text{ kJ/kg K} \).
15. Describe the process of formation of steam and give its graphical representation also.

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SECTION-C

16. 0.45 kg of carbon monoxide (28) and 1 kg of air at 15°C are contained in a vessel of volume 0.4 m³. Calculate the partial pressure of each constituent and the total pressure in the vessel. The gravimetric analysis of air is to be taken as 23.3% oxygen (32) and 76.7% nitrogen (28).
17. 1. Prove that the rate of change of heat interchange per unit change of volume when gas is compressed or expanded is given by \( \frac{\gamma - n}{\gamma - 1} p \frac{dv}{v} \).
    2. For isothermal flow and non-flow steady processes, prove that \( \int_1^2 p dv = - \int_1^2 v dp \). Also state the assumptions made.

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18. Write short notes on the following :
    1. Perpetual motion machine of second kind.
    2. Clapeyron equation and its applications.
    3. Helmholtz and Gibbs function.
    4. Measurement of dryness fraction.

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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.

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