PHYSICAL MODELING OF GAS-DIESEL ENGINE OPERATIONAL PROCESS

Abstract

Conversion of engines to natural gas feeding is actual due to the lower cost of gas fuel and improvement of environmental performance. Within the works on creation of high- and medium-speed transport engines powered by natural gas conducted at MADI, an electronic control system and a modular gas supply system for a gas-diesel were developed and manufactured. This approach allowed using of three modules for feeding of the medium-speed gas diesel 6ChN20/28 and one module for the high-speed gas diesel 6ChN10.7/12.4. For experimental testing of the systems, at MADI there was made the conversion of the 6ChN10.7/12.4 diesel into a gas-diesel with a minimized igniting portion the diesel fuel supplied by the Common Rail system. Calibration of gas-diesel systems was carried out using the results of experimental studies and the computational complex developed at MADI for modeling of working process of a gas-diesel engine. Bench tests of the high-speed gas diesel showed that the developed systems of gas supply and electronic control allow obtaining of a large portion of gas substitution of diesel fuel (from 5 % for full loads to 33 % for small ones), high effective indicators, and notable reduction of NOx and CO2 emissions. It was not possible to obtain the high level of torque as for the base diesel engine, at low speeds. Comparative calculations of the medium-speed gas diesel engine 6ChN20/28 and high-speed gas diesel engine 6ChN10.7/12.4 were carried out under similar conditions (the same average piston velocity, mean effective pressure and charge air pressure), which showed close indicator values, that allows to expect the efficiency of the medium-speed gas diesel systems of fuel supply and electronic controls designed for high-speed gas diesel engines after their respective adaptation.