Modeling of Quasi-Steady State Heat Transfer Phenomena with the Consideration of Backflow Gas Effect at Intake Manifold of IC Engines and its Numerical Analyses on 1-D Engine Simulation 2018-32-0029
As of early 21st century, automotive industry is genuinely involved with hybrid and electrical vehicles. However, it is safe to say that these new trends are considered to be available solely for developed countries. In a wider perspective, effect and importance of diesel engines still account an important role in the developing countries such as China, Indonesia and so forth. Thus, its performance and efficiency measures still play a crucial aspect both for economy and environment. In order to improve the thermal efficiency and performance of internal combustion engines, it is necessary to model the heat transfer phenomenon at the intake system and predict intake air mass flow rate into the engine cylinder. In the previous studies, the heat transfer phenomenon at the intake system was modeled as quasi-steady assumptions, based on Colburn analogy. Authors developed an empirical equation with the introduction of Graetz and Strouhal numbers, using a port model experimental setup. In this study, for further improvement of the empirical equation, real engine experiments were conducted, where pressure ratio between the intake manifold and engine cylinder were added along with Reynolds number to characterize the backflow gas effect on intake air temperature. Compared to the experimental data, maximum and average errors of gas temperature estimated from the new empirical equation were evaluated to be 2.8% and 0.9%, respectively. Furthermore, for validation and verification, Colburn analogy and newly derived empirical equation were implemented to a 1-D engine simulation. Simulation results confirmed the influence of the backflow gas, and its importance on intake air. At 2250 rpm, in-cylinder gas temperature difference, at IVC, between Colburn equation and derived equation was calculated to be 5.8 K. This corresponded to an advanced auto-ignition timing by 1.15 deg. CA, which could be interpreted an estimated reduction of CO2 gas by 0.28%.