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Basic Thermodynamics & &
Max. Marksrl00'
Time: 3 hrs. Note:
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PART_A
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general than the definition of woft,ifl (04 Marks) A gas expands quasi-staticalffi'"a piston cylinder affangement against the atmosphere and a spring. Initial pressure and voiume are 400 KPa and 0.2 m3 respectively. The final volume of gas is 0.6 m3. Determine,the total work done by the gas if the spring force is proportional to (08 Marks) volume of the gas. Assume the atmospheric pressure as 101 .325 gas Daroulr is ls inside the lnsloc rne balloon ar zuu 200 KPa. Nra. The r ne A spnencar spherical balloon looii"of diameter contains corualns a gas at DaIrGOn of 1I1 m olameler oI heated until t\erptrrssure hrbssure reaches 500 KPa. During the process of heating, the pressure of the gas inside tt-@[oon is proportional to the diameter of the balloon. Calculate the work done (08 Marks) by the g*slffiSiae the
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frst law ;* equation for a closed system undergoing a non cyclic
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process and show show (08 Marks) property of energy is a a t&t1t*fl1fsrnrl b* {Modify the general steady flow energy equation (SFEE) for the following cases: ',... ) (r) Steam turbine with negligible potential energy change if the process is adiabatic. (ii) is re vv rlu negligible neslisible uwSrrSlulw wllLr4lrww velocity velocitv vwrvwrlJ vr steam, steam. rlv4r[, ifrr the uuv process Horizontal JlWOul steam twLbt9 nozzle with entrance of oror \uJ' rrvr&VlrL4r HrvvvrD S non-adiabatic. (06 Marks) (iii) Insulated horizontal throttle In a centrifugal compressor, the suction and delivery pressures are 100 KPa and 550 KPa respectively. The compressor draws f s has a specific volume of 0.77 nl lkg. At the delivery the specific volume is 0.20 m'lkg. The compressor is driven by a 40 KW motor, and heat lost to the surroundings during compression is 30 KJikg of air. Neglecting change in potential and kinetic energy, calculate increase in internal energy per (06 Marks) kg of a.
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2 a. Write the thermodynamic definifio-ffiwork. With suitable example explain how it is more
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measurement.
(06 Marks) temperature A constant volume gas thermometer containing helium gas gives readings of gas pressure 1000 mm and 1366 mms of mercury at the ice point and steam point respectively. i) Express the gas thermometer Celsius temperature interms of gas pressure. ii) The thermometer when left standing in the atmosphere, registers 1075 mm of mercury. *' (08 Marks) Determine vvlwltrlulw the lrrw atmospheric aLurvoPlrwrrw temperaturq. lwrrrHwrqll
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Differentiate between: (i) Control mass and control volume (ii) and classify the following into intensive and exte-osive properties. (i) Enthalpy s*a.r;r,,,.,.H,,:r.t.ii;.q{:,.-.,., ,,. ",pfopofties, (06Marks) (ii) Qualityofsteam (iii) Entropy and(iv) Density. $I b. Define the zeroth law of thermodynamics and explain how this law forms the basis for gE E
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air.
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b. c.
Write Kelvin-Planck and Clausius statements of second law of thermodynamics. Show that violation of Clausius statqment lbads to the possibility of a perpetgpl motioo-nraehiae-Gf,..,.,:!.-*d second type.
(10 Marks)
Mention the factors that make a process irreversible. (04 Marks) Using a heat engine of thermal efficiency 30Yo to drive a refrigerator having a COP of 5, what is the heat received by the heat engine for each MJ of heat removed from the roqQ&ry of the (Q6M{dO (mrt&n.l
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refrigerator.
Define the following:
(i) Pure substance (ii) Triple porqq r \iiil
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gas
equati$u.
Tyt-t:Constant.
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air (iii)
Work transfer (10 Marks)
what ways, it is an improvement over the ideal (06 Marks)
Explain the following: Compressibility factor Reduced properties iil) Law of corresponding states iv). Generalised compressibility chart. (08 Marks) Determine the specific volume of hydrogen gas when its pressure is 60 bar and temperature is 100 K by using, (i) Compressibility chart (ii) Vander Waal's equation
Take fof Hz
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(06 Marks)
Starting from the relation Tds = aupfuv, show that for an ideal gas undergoing a reversible adiabatic process, the law for the prbcess is given by (06 Marks) Clearly distinguish between ideal and real gases. (04 Marks) A quantity of air at a pressure of i00 KPa, 27"C occupying ? volume of 0.5 m3 is compressed to a pressure of 500 I(Pa and volume of 0. T2 fiS according to the law
Write the Vander Waals equation of state.
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PVn = constant. Find (i) The value of index 'n' (ii) The mass of Heat transfer during the process (v) Change in entropy.
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calorimeter. (08 Marks) Calculate the internal energy per kg of supeqlppl.ed steam at pressure of 10 bar and a temperature of 300'C. Also find the change;@qnfernal energy if this steam is expanded to I.4 bar and dryness fraction (06 Marks)
(iv)
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point.'
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Critical
(06 Marks)
With neat sketch explain the measurement of dryness"fraition of steam by using throttling
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7a.
7oC and 27oC ght into contact
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(04 Marks)
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Derive Clausius unequality and prove that entropy is a property. Explain the principle of increase of entropy. Two copper blocks weighing 10 kg each are initially at tempe respectively. What is the change in entropy when these two b with each other? Take specific heat of copper as 0.4 KJ/kgK.
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PART _ B
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Tc =239.760C
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, Pc :
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a=0.25105x105Nm2/kgmola, (06 Marks)
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