MT 313 IC ENGINES

LECTURE NO: 03(19 Feb, 2014)

Khurram

engr014@yahoo.com

Yahoo Group Address: ICE14

QUESTIONS

• What is the advantages and Disadvantages of four stock engines?

• What is the advantages and Disadvantages of two stock engines?

• What is the advantages and Disadvantages of Petrol engines?

• What is the advantages and Disadvantages of Diesel engines?

• What is the advantages and Disadvantages of Wankel stock engines?

• Compare 4 - stroke & 2 - stroke Engine?

QUESTIONS• Describe working principles of Wankel engines?• Numerate performance parameters of the I.C. engines?

Ideal cycles are simplified

Ideal Cycles

• More realistic than Carnot cycle.• Internally reversible but not totally.• Idealizations:

– No friction– Expansions and compressions – quasi-equilibrium– Heat transfer is negligible

Different Processes

Isobaric Isometric

Adiabatic ΔT ≠ 0 but Q = 0

IsothermalΔT = 0 but Q ≠ 0

CyclicIf clockwise – heat engine

If counterclockwise – heat pump

Area inside the cycle represents net work out for TS or PV diagrams.

Otto Cycle, ideal for spark ignition engines

TS plot of the Otto Cycle

Efficiency vs Compression Ratio

Higher ratios produceautoignition andknocking

Efficiency vs ratio of specific heats

Air

Combustionmixture

He

The Ideal Otto Cycle