I.C. ENGINES

1. I.C. ENGINES Practical No: 3 (22 Apr, 2014)

2. Report Writing • Title • Date • Object • Reason for carrying out the experiment and whether it s to prove some theory • Apparatus • Specification of engine

3. Report Writing • Apparatus • Specification of engine and equipment • Clear description if the apparatus used • Illustrated by simple diagrams and photos

4. Report Writing • Procedure • An account of things done before and during the experiment • Results • Record of all data • Reading taken before and during the experiment • Results should be in tabulated form

5. Report Writing • Results • Formula used foe the calculations and one specimen of each type of calculation should shown • Graphs drawn to show the results must be clearly marked with • Title • Date • Scales

6. Report Writing • Conclusions • An account of any incident or event during the experiment • Suggestions why the experiment and theoretical results do not agree • Do not always blame the equipment

7. Report Writing • Hints • Always write in past tense • Make no personal references • Examples • Weights were placed on the carrier • Reading were observed at two minutes intervals • Engine speed was increased • Temperature was constant

8. Brake Power Test • Apparatus • Hydraulic or electrical dynamometers are used for the testing • Dynamometer • Dynamometer can measure the output torque when driven by engine • Also measure input torque when used as electric motor to drive or rotate engine

9. Brake Power Test • Dynamometer • The motoring test if carried out when engine is cold gives a measure of the load which would be put on the starter motor when the engine is in the vehicle • Further tests can be carried out at various engines temperatures including extreme starting conditions and with different grades of lubricant oil

10. Brake Power Test • Dynamometer • Motoring the engine at normal working temperature enable the friction and pumping losses to be determine • For pumping losses engine can be relieved of its effective compression by removing the spark plugs or injector the remaining losses are frictional

11. Calculation for Power and Torque • Pb= 2 𝜋 FL ( rev/sec)

12. Calculation for Power and Torque • If = Constant say kc • Then

13. Example • A four cylinder , four stock engine has a piston area of 0.008 m2and stock of 0.025 m and it is tested against a dynamometer with torque arm of 0.4475 m, • P ( brake power) is given by • Torque in Nm by F • and b.m.e.p (break mean effective pressure) in kN/m2 by F • Where F = break load in N and , and are constants dependent upon the dimensions. • Find the values of , and

14. Example • Data • Formula • Sol • To find

15. Example • Sol • = 20

16. Example • Sol • F x 0.4775 ( Nm) • = 0.4775 • For • Work done = Force x Displacement( Nm) • = m.e.p x Area x Stock ( Nm) • = pAL • Work done / sec = p x A x L x S ( no of stocks)

17. Example • Sol • i.m.e.p= work done / sec • Indicated Power (Pt) = p x L x Ax S • b.m.e.p = 𝜂 Pt

18. Example • Sol • Now Brake Power = = • = 1500