Numerical study of the process of compressing a turbulized two-temperature air charge in the diesel engine

• Main Authors: Anatoliy Kasimov, Kostyantyn Korytchenko, Dmytro Dubinin, Andrei Lisnyak, Evgen Slepuzhnikov, Igor Khmyrov
• Format: Article
• Language: English
• Published: PC Technology Center 2018-12-01
• Series: Eastern-European Journal of Enterprise Technologies
• Subjects: cold start; diesel engine; numerical study; compression process; engine start facilitation
• Online Access: http://journals.uran.ua/eejet/article/view/150376

We have investigated the issue on improving energy efficiency of systems that facilitate the start of diesel engines by heating the air charge. The enhanced energy efficiency is based on the heating of part of the charge only. The result is the formed air charge in the engine cylinder, which consists of two layers of air with different temperatures. To substantiate the new method for facilitating the cold start of the multi-liter diesel engine, a numerical study into the compression of a different-temperature air charge in the engine was conducted. Using an engine of the type 6TD as an example, we have numerically studied a change in the temperature field of the charge at compression, taking into consideration the vortex flows that arise when a charge forms in the engine's cylinder. Based on an analysis of the temperature field in the charge, we have identified the existence of conditions for a reliable self-ignition of fuel in the charge at its compression. In order to form two layers of air with a different temperature, we first assigned, under conditions of modeling, the injecting of cold air into the engine's cylinder at a temperature of 253 K. Next, the heated air was injected at a temperature of 773 K. A volumetric fraction of the heated air in the charge was 10 %. Based on the simulation results, it was established that the existence of charge layers with different temperatures is retained at compression. We have confirmed that the temperature of the fuel auto-ignition in the pre-heated layer of air could be achieved at the intake air temperature of −20 °C. The results obtained could be applied to substantiate the requirements for the energy-efficient systems that facilitate a cold start of the diesel engines