UNIT-I
1. (a) Define cylinder row and cylinder bank.2
(b) Explain the valve timing diagram for S.I.and C.I. engine and also give effect of valve timing and engine speed on volumetric efficiency of the cycle.7
(c) Show that the compression ratio (r) for the maximum work to be done per kg of air in an ideal otto cycle between upper and lower limits of absolute temperature T3 and T1 is given by .........
(d) An engine working on otto cycle, having compression ratio 7, uses hexne as the fuel . Thecalorific value of the fuel is 10,500 kcal/kg. The air fuel ratio of mixture is 13.67:1, If specific heat at constant volume is 0.17 , compression follows the law Pv1.3 = C . The pressure and temprature of the mixture at the begining of compression is 1 kgf/cm2 and 67 degree C respectively. Determine maximum pressure and temprature reached in the cycle. 7
UNIT-II
2. (a) Discuss the use of LPG as S.I. engine fuel.
(b) Explain the terms in brief:
(i) Vapour lock
(ii) Carburetor icing
(iii) Critical compression ratio
(iv) Performance number
(c) The analysis of the dry exhaust from an internal combustion engine gave : 12%CO2; 2%CO; 4%CH4; 1%h2; 4.5% o2; and remainder nitrogen.Calculate the proportions by mass of carbon to hydrogen in the fuels, assuming it to be a pure hydrocarbon.
(d) "Factor tending to increase detonation in in S.I. engines tends to reduce knok in C.I. engines." Discuss the validity of the above statement in the light of the difference in the nature of the two phenomenon and indicate the methods used to reduce knock in C.I engine.
UNIT-III
3. (a) Give the advantages of petrol injection system.
(b) Describe with suitable sketches the following systems of carburettor.
i. Main metering system
ii. Idiling system
iii. Power enrichment or economizer system
(c) Derive an expression for air-fuel ratio taking compressibility into account.
(d) The four-strko petrol engine of Hindustan Ambessador has a capacity of 1489 cc. It developes maximum power at 4200 rpm. The volumetric efficiency at this speed is 70 % and the air-fuel ratio is 13:1. At peak power the theoretical air speed at chock is 90 m/sec. The coefficient of discharge for the venturi is 0.85 and that of the main petrol jet is 0.66. An allowance should be made for the emulsion tube, the diameter of which can be taken as 1/2.5 of the coke diameter. The petrol surface is 6 mm below the choke at this engine condition. Calculate the sizes of the suitable choke and main jet. The specific gravity of the petrol is 0.74. Take atmospheric pressure and temprature are 1.013 bar and 20 degree C respectively.
UNIT-IV
4 (a) Draw a typical heat release diagram of diesel engine.
(b) Write short notes on the following :
Electronic ignition system
Spray penetration and spray direction of injection system
Antifreeze mixture
Mist lubrication system
(c) Derive an expression for the amount of fuel injected per cycle in terms of brake horse power and speed of a four stroke diesel engine.
(d) Compare the transistorised ignition system with a capacitor discharged system. Highlight the advantages of each system.
UNIT-V
5. (a) What is a flame ionisation detector? 2
(b) How pressure-crank angle diagram can be obtained from pressure-volume? For what purpose pressure crank angle diagram is superior to pressure volume diagram?
(c) Describe the working principle of any two of the following:
i. Bosch smoke meter
ii. Willian's line
iii. Light spring diagram
iv. Infrared gas analyser
(d) What is meant by total emmission control packages?Describe with sketches the two types of total emmition control package.
