Thermodynamic modeling and validation of in‐cylinder flow in diesel engines

Abstract

The formation of a suitable air and fuel mixture in diesel engines is one of the most important factors in quality of combustion and engine exhaust emissions. The mixture formation depends on mass transfer phenomenon inside the combustion chamber. This study presents a new thermodynamic model to simulate the mass transfer phenomenon in diesel engines. Diesel engine is simulated utilizing a thermodynamic multi zone model coupled to a semi‐detailed chemical kinetics mechanism. Heat and mass transfer submodels are linked to the multi zone model. Bulk flow and diffusion mass transfer between zones are considered in the mass transfer submodel. Bulk mass transfer simulates fluid motion between different zones caused by piston speed and difference in zonal temperature and pressure. Diffusion mass transfer occurs due only to difference in composition of different zones. The results indicate diesel engine performance and exhaust emissions can be predicted accurately applying mass transfer submodels. Bulk mass transfer mechanism has more significant effects on engine performance and emission compared to diffusion mechanism. Neglecting mass transfer submodels, calculated in‐cylinder peak pressure is under predicted and both of exhaust NOx and soot are over predicted. The rates of soot oxidation reactions decrease and rates of NOx important reactions increase when mass transfer submodels are ignored. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Review and Synthesis of Literature on Single and Multizone Thermodynamic Combustion in a Diesel Engine

“…With regard to mass transfer, each zone can be thermodynamically defined as a closed or open thermodynamic system, depending on whether the mass flow between the zone is more or less important. Similarly, heat transfer between zones and to the combustion chamber wall can also be allowed or neglected [1,2,33,11]. However, assumptions about mass and heat transfer can be factors influencing the simulation results significantly; heat transfer affects the temperature stratification inside the combustor, the cooler regions of which are sources of unburned HC and CO. For some authors, the formation of these pollutants is also affected by mass transfer between zones, since any HC or CO moving from a colder to a warmer zone is expected to be (partially) oxidised [31,36,37].…”

“…The relative air-to-fuel ratio was changed from 0.8 to 1.53 and the nominal mean effective brake pressure was changed from 0.2 to 1.5 MPa to 1.29 MPa. E. Neshat et al, 2019 [11] present a new thermodynamic model to simulate the mass transfer phenomenon in diesel engines. The simulation in the diesel engine was done using a multi-zone thermodynamic model coupled with a semi-detailed chemical kinetics mechanism.…”

“…We analyse the influence of the parameters and the thermophysical and physicochemical properties of the fuels used on the engine performance. We recall that the objective is to make a literature review and to highlight the different thermodynamic numerical models used during the combustion of fuels in a diesel engine combustion chamber [9][10][11][12][13]. Finally, the novelty of this study is to summarise the work done on thermodynamic modelling over several years.…”

The formation mechanisms of flow field in a compound intake ported rotary engine considering apex seal leakage

“…For the flow field research, a lot of in‐depth work on reciprocating engines has been done. For instance, the influences of the flow field on fuel atomization, 15 combustion process, 16 emission, 17 and volumetric efficiency 18 have been deeply studied. All these results have contributed greatly to the improvement of combustion performance of reciprocating engines.…”