THERMODYNAMICS - TEN YEAR / PAPER - 1

PAPER – 1

LAST YEAR QUESTION PAPER

THERMODYNAMICS  

Que – 1(a): DEFINE THE FOLLOWING

               QUASI STATIC PROCESS, THERMODYNAMIC EQUILIBRIUM, HEAT & WORK, INTENSIVE AND EXTENSIVE PROPERTY

Que – 1(b): IN A PISTON CYLINDER ARRANGEMENT, THE NON FLOW REVERSIBLE PROCESS IS GIVEN BY V = 200/PM³, WHERE P IS IN BAR, FIND THE WORK DONE WHEN THE PRESSURE INCREASES FROM 1 BAR TO 10 BAR. INDICATE THAT THE PROCESS IF COMPRESSION OR EXPANSION.

QUE – 2(a): PROVE THAT THE MOLE FRACTION OF EACH CONSTITUENTS IN A MIXTURE OF PERFECT GASES IS THE SAME AS ITS VOLUME FRACTION AND ALSO, THE RATIO OF ITS PARTIAL PRESSURE TO THE TOTAL PRESSURE.

 QUE – 2(b): A MIXTURE OF GASES HAVING 2 KG HE AND 5 KG N₂ AT 30⁰ C AND 1 BAR IS COMPRESSED IN A REVERSIBLE ADIABATIC PROCESS TO 6 BAR. FIND:

                                    i.            FINAL PRESSURE OF THE CONSTITUENTS

                                  ii.            THE FINAL TEMPERATURE

                                iii.            CHANGE IN INTERNAL ENERGY OF THE MIXTURE DURING PROCESS

TAKE (C_S)N₂  = 0.744        ,            (C_V)_HE  = 3.157

           (C_P)N₂ = 1.049        ,             (C_P) _HE = 5.296KJ/KG⁰K

QUE – 3: THE MASS FLOW RATE OF AIR THROUGH A RECIPROCATING COMPRESSOR IS 0.4 KG/SEC.THE AIR ENTERS AT 6 M/SEC. WITH A PRESSURE OF 1 BAR AND SPECIFIC VOLUME OF 0.85 M³ KG AND LEAVES AT 4.5 M/SEC WITH A PRESSURE OF 6.9 BAR AND SPECIFIC VOLUME OF 0.16 M³/KG. THE EXTERNAL ENERGY OF THE AIR LEAVING THE COMPRESSOR IS 88 KJ/KG GREATER THAN THAT OF AIR ENTERING COOLINGWATER OF THE CYLINDER JACKET ABSORBS HEAT AT A RATE OF 59 KW. DETERMINE THE POWER REQUIRED TO DRIVE THE COMPRESSOR AND INLET AND OUTLET PIPE-CROSS-SECTION AREAS.

QUE – 4(a): WHAT ARE THE LIMITATION OF FIRST LAW OF THERMODYNAMICS? STATE THE SECOND LAW AS STATED BY KELVIN – PLANK AND CLAUSIUS ALSO PROVE THEIR EQUIVALENCE?

QUE – 4(b): AN ENGINEER CLAIMS HIS ENGINE TO DEVELOP 3.675 KW ON TESTING THE ENGINE CONSUMES 0.44 KG OF FUEL PER HR HAVING A CALORIFIC VALUE OF 41800 KJ/KG. THE MAXIMUM TEMPERATURE RECORDED IN THE CYCLE IS 1400⁰C AND MAXIMUM IS 350⁰C. FIND WHETHER THE ENGINE IS JUSTIFY IN HIS CLAIM. IF HOWEVER THE MAXIMUM & MINIMUM TEMP. ARE MAINTAINS AT 200⁰C AND 250⁰C, WILL THE PERFORMANCE BE POSSIBLE AN THE SAME ENGINE

QUE – 5(a): STATE AND PROVE THE CLAUSIUS INEQUALITY

§dQ/T < 0 , FOR IRREVERSIBLE PROCESS

§ Dq/T = 0 , FOR A REVERSIBLE PROCESS

QUE – 5(b): 2 KG OF WATER AT 94⁰C IS MIXED WITH 3 KG OF WATER AT 10⁰C IN AN ISOLATED SYSTEM. CALCULATE THE CHAGE IN ENTROPY DUE TO MIXING PROCESS?

QUE – 6(a): DERIVE AN EXPRESSION FOR AVAILABILITY OF A STEADY FLOW SYSTEM?

QUE – 6(b): CALCULATE THE UNAVAILABLE EVERY IN 60 KG OF WATER AT 60⁰C WITH RESPECT TO THE SURROUNDINGS AT 6⁰C, THE PRESSURE OF WATER BEING I ATMOSPERE.

QUE – 7(a): EXPLAIN THE WORKING OF A THROTTLING AND SEPERATING CALORIMETER FOR THE MEASUREMENT OF DRYNESS FRACTION OF STEAM. WITH THE HELP OF NEAT SKETCH.

QUE – 7(b): CALCULATE THE INTERNAL ENERGY PER KG OF SUPERHEATED STEAM AT A PRESSURE OF 10 BAR AND A TEMPERATURE OF 300⁰C. ALSO FIND THE CHANGE OF INTERNAL ENERGY IF THIS STEAM IS EXPANDED TO 1.4 BAR AND DRYNESS FRACTION 0.8.

QUE – 8 : DERIVE THE FOLLOWING RELATIONS:

(a) Tds = C_V dT + p T Dv/K

(b)TdS = C_P Dt – VβTdP

(c) TdS = C_VK/βV  dV