ID 380

Effect of Cryogenic Intake Air Temperature on the Equivalence Ratio Distribution Characteristics in CI Engine Cylinder

Se Hun Min
Graduate School of Mechanical Engineering, Kongju Nat’l Univ.
South Korea

Hyun Kyu Suh
Div. of Mechanical and Automotive Engineering, Kongju Nat’l Univ.
South Korea

Seongjin Jo
3Department of Mechanical Engineering, Graduate School of Chonnam National University
South Korea

Suhan Park
of Mechanical Engineering, Chonnam National University
South Korea

Abstract:

The objective of this study is to numerically investigate the effect of cryogenic intake air temperature conditions on a formation of air-fuel mixture and combustion performance in a compression ignition (CI) diesel engine. The numerical results were validated with experimental results in order to ensure the reliability of the results. The experimental setup for the validation is consisted of a single-cylinder diesel engine, an intake air temperature regulator, an engine controller, an injector driver, and an exhaust gas analyser. The intake air temperature for the cryogenic condition was controlled by cooler and heater, and the intake air flow rate was maintained by gas flow controller. Sub-models such as Wave, Walljet-1, Dukowicz and ECFM-3Z were applied for the simulations of physical/chemical phenomenon of spray and combustion behaviors. The intake air temperature was varied from -18℃ to 18℃, and the injection timing was changed from BTDC 18deg to BTDC 06deg. The results of this work were compared in terms of cylinder pressure, rate of heat release (ROHR), indicated mean effective pressure (IMEP), indicated specific nitrogen oxide (ISNO), indicated specific carbon monoxide (ISCO), equivalence ratio distributions and ignition delay. The equivalence ratio was reached to the peak value slowly according to the intake air temperature because the injected fuel was evaporated lately by the low intake air temperature. When the intake air temperature became lower, ignition delay became longer because the combustion performance was deteriorated due to the low cylinder temperature. When the intake air temperature was decreased in steps of 9℃, the cylinder temperature and cylinder pressure were decreased in steps of about14.5℃ and 0.05MPa, respectively. Therefore, the ISNO value was also decreased, and the ISCO was increased. IMEP value was increased since the compression loss of the piston is reduced due to the longer ignition delay.