MECH - 4020340 - THERMAL ENGINEERING I STUDY MATERIALS

2. A gas has a mass of 3 kg at initial pressure of 8 x 10° N/m’ expands adiabatically till the pressure falls to 4x10°N/m’, During the process 120kNm of work is done by the system and the temperature falls from 377°C to 257°C. | Find the value of index of expansion and characteristic gas constant.

3. 1 kg of gas expands is entropic ally and its temperature is observed to fall from 24°C to 110° while its volume is doubled. The work done by the gas is 90 KJ in the process. Determine CP, CV and R for the gas.

4.0.675 kg of gas at 14 bar and 280°C is expanded to four times the original volume according to law pv1.2=C. Determine a) the initial and final volume of gas b) final pressure and temperature of gas c) Work done. R=287 J/kg k.

5.0.5kg of air at 180°C expands adiabatically to 3 times its original volume. During the expansion, the temperature is decreased to 20°C. Work done during expansion is 53kNm. Fine the Cp,Cv and R. (Answer: C, = 0.9252 kJ/kgK, C, = 0.6625 kJ/kgK, R = 0.2627 kJ/kgK)

Unit-2

1.In an Otto cycle the pressure and temperature of the air at the beginning of compressions are 97 KN/m’ and 5SO°C respectively. The ratio of compression is 5:1.The heat supplied during the cycle is 970 KJ/kg of the working fluid. Determine(i) Maximum temperature of the cycle, (i) the thermal efficiency of the Cycle and (iii) work done during the cycle per kg of working fluid. Assume1.4 and CV= 0.717 K J/kg k. ii) 2.Discuss about heat transfer by conduction. ;

3.Find the power output of a diesel engine working on a standard diesel cycle with a Compression ratio of 16 and air flow rate of 0.25 kg/s. The initial condition of air is at 1 bar pressure absolute and 27°C temperature. Heat added per cycle is 2500 . ; KJ/kg. Assume C, = 1.0 K J/kg K and C\= 0.7 14kJ/kg k. li) 4.Derive the steady flow energy equation and state the assumption made in the System analysis.

Unit-3

1. Explain the working of four stroke petrol engine with a neat sketch.

2.Explain with neat sketches MPFI system. 3.Describe Battery coil ignition system with neat sketches. | . it) 4.Explain the high pressure lubrication system with a neat sketch.

Unit-4

1. With a neat sketch, explain the method of determining the calorific value of . gaseous fuel using Junker's gas calorimeter.

2.During a trial of fourstroke single cylinder oil engine the following Obs ervations were recorded: Quration of trial : One hour. fuel consumption 2 7.05 kg/hr Calorific value : 44000 kJ/kg. pugine speed ae 210r.p.m Net load oO” br ae er > 1350N prake drum wiacket cooling water *600 mm. ymas> 0") ing water 495 kg. F qeta rise of cooling . 38°C. qeoP ar ture of exhaust gases . 300°C pom sumption erature 311 kg. pire eroo™ temP ° 20°C, . of Sp.heat of exhaust gases : 1.004kJ/kgK. ‘4 n Specific heat of water : 4.1868 kJ/kgK. . Draw up a heat balance sheet of the trial.

The following results were obtained during a test on four cylinder four stroke oil Engine: Bore — 100 mm, stroke — 115 mm, speed — 1650 rpm; Fuel used—0.2 kg 0.2 kg/min; calorific value of fuel — 41900 KJ/kg; Net load on the brake drum -390N; Circumference of the brake drum — 3.3m;Mechanical efficiency — 80%; 3.Determine a) Brake thermal efficiency b) Indicated thermal efficiency and c) Indicated mean effective pressure.

4.Explain the Morse test for finding out the indicated power of a multi cylinder engine.

Unit-5

1.With a neat flow diagram explain the working ofa vapour absorption refrigeration

2.With the help of a line diagram, explain the working ofacentral air—conditioning System.

3. Name the psychrometric processes and explain sensible heating and cooling briefly.

4. Explain the factors gate considered in air conditioning.

NSK EDUCATION - TAMILAN ULAGAM

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MECH - 4020340 - THERMAL ENGINEERING I STUDY MATERIALS

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