THERMODYNAMICS  CASE STUDY



Introduction

Presentation


During Max's presentation of his senior capstone design
project, someone asks him about comparisons between sparkignition (SI)
engine and compressionignition) CI engine.
What is known:
 The displacement volume of each cylinder is 1.0 L.
 The crankshaft rotates at 2600 RPM.
 The clearance volume is 15% of the volume when the piston
is at the bottom dead center (BDC).
 The pressure and temperature of the gasfuel mixture just before
compression are:
P = 100 kPa and T = 15^{o}C
 The maximum temperature the engine cylinder can tolerate is T = 1800^{o}C.






Question



 Determine the thermal efficiency and compression
ratio using the ideal Ottocycle model.
 For the same temperature limits and equal
amounts of heat input, which airstandard cycle has a higher thermal
efficiency, Otto or Diesel? Which one has the higher compression ratio?






Approach



Model the cycle of this engine as an airstandard
Ottocycle and Dieselcycle, respectively. Calculate their thermal efficiencies
and compression ratios.



