ME2202 Engineering Thermodynamics Important Questions

1. A paddle wheel fixed to a shaft of an engine revolves in a closed hollow vessel

Containing water. This closed vessel is connected freely on the shaft and restraint to its

turning moment is proved by mass attached to its side. Find the temperature rise for the

following observations.

Engine rpm = 650, Load applied = 60 kg at a leverage of 1.2m,

Quantity of water = 200 kg Duration of test

2. A cylinder contains 0.45 m3 of gas at 1 x 105 N/m2 and 80oC. The gas is compressed to

a volume of 0.13 m3, the final pressure being 5 X 105 N/m2. Determine i) The mass of

gas ii) The value of index ‘n’ for compression The increase in internal energy of the gas

and iv) The heat received or rejected by the gas during compression. Take γ = 1.4 R =

294.2 J/kg K

3. A turbine operates under steady flow condition receives steam at the following state

pressure = 1.2Mpa, Temperature =1880C, Enthalpy = 2785 kJ/kg, velocity = 33.3m/sec

and elevation = 3m. The steam leaves the turbine at the following state: pressure =

20Kpa, Enthalpy = 2512 kJ/kg, velocity = 100m/sec and elevation = 0m. Heat is lost to

the surrounding at the rate of 0.29kJ/sec. If the rate steam flow to the turbine is 0.42kg/

sec what is the power output of the turbine in KW

4. Three grams of nitrogen gas at 6atm and 160°c is expanded adiabatically to double its

initial volume, then compressed at constant pressure to its initial volume and then compressed

again at constant volume to its initial state. Calculate the net work done on

the gas. Draw P-V diagram for the process. Specific heat ratio of nitrogen is 1.4.

5. One litre of hydrogen at 273 K is adiabatically compressed to one-half of its initial

volume. Find the change in temperature of the gas, if the ratio of two specific heats for

hydrogen is 1.4

6. An Engine-working on Otto cycle has a volume of 0.45 m3 , pressure 1 bar and

temperature 30o,C at the beginning of compression stroke. At the end of compression

stroke, the pressure is 11 bar and 210 KJ of heat is added at constant volume. Determine

(i) Pressure, temperature and volumes

at salient points in the cycle.' (ii) Efficiency

7. Derive the expression for thermal efficiency of a Carnot cycle with its p-V and Ts

Diagram?

8. A Carnot engine takes heat from an infinite reservoir at 5500C and rejects it to a sink

2750C. Half of the work delivered by the engine is used to run generator and the other

half is used to run heat pump which takes heat at 2750C and rejects it at 4400C. Express

the heat rejected at 4400C by the heat pump as % of heat supplied to the engine at

5500C. If the operation of the generator is 500W, Find the heat rejected/hour by the heat

pump at 4400C?

9. Establish the inequality of Clausius and express Entropy change in irreversible

process

10. 1 kg of steam initially dry saturated at 1.1 MPa expands in a cylinder

following the law PV113 = C. The pressure at the end of expansion is 0.1 MPa. Determine

(i) The final volume (ii) Final dryness fraction (hi) Work done (iv) The change in

internal energy (v) The heat transferred

11. Draw the p-V diagram of pure substance and explain its various regions of the

diagram in details?

12. with help of T-s diagram explain the various process of ideal Rankine’s cycle

and derive the efficiency in terms of enthalpy?

13. Steam at a pressure of 15 bar and 250°C expands according to the law PV1.25 =

C to a pressure of 1.5 bar. Find the final conditions, work done, heat transfer and change

in entropy. The mass is 0.8 kg

14. Derive clausius-claperyon equation

15. Deduce the Maxwell relations from thermodynamic property relations?

16. Using Clausius Cleperyon’s equation, Estimate the enthalpy of vaporization at

2200C saturation temperature. Take the following data Ts = 2200C; vg = 0.08603m3/kg;

vf =0.00119m3/kg.

17. 2kg of air at 300C, 65% RH is mixed adiabatically with 5kg of air at 200C,

10%RH. Determine final condition of the mixture?

18. Give short notes on following (a) Specific humidity (b) Relative humidity (c)

Dew point temperature (d) Wet bulb depression

19. Air has a dry bulb temperature of 250C and wet bulb temperature of 150C. If

the barometer reads 1bar, Calculate

(a) Vapour pressure

(b) Specific humidity

(d) Relative humidity

(e) Dew point temperature

(f) Vapour density

(g) Enthalpy of mixture

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