DVIGATELESTROENIYE # 4 (246) 2011

SYNOPSIS

ANALYSES, DEVELOPMENT AND CONSTRUCTION OF ENGINES

Keywords: HCCI engine, homogeneous charge combustion, exhaust gas recirculation, inert components, oxygen activity. The author offers an expression for oxygen activity coefficient that takes account of how fuel combustion rate is influenced by contents of inert components in combustible mixture. Said coefficient has been determined for dimethyl ether combustion in air mixed with exhaust gas. Combustion rate vs. inert components' contents in exhaust gas has been studied.

Keywords: reciprocating diesel engine, propulsion unit, transient, dynamic equations. Discussed are transients in a diesel-powered marine propulsion unit consisting of diesel engine, gearbox and variable-pitch propeller. Dynamic equations for the above components are derived. The set of equations is solved with 4th order Runge-Kutta method that allows taking account of (varying) equation coefficients at each integration step. Transients are considered caused by load changes and disturbances applied to fuel supply system.

ENVIRONMENTAL ISSUES

Keywords: reciprocating diesel engine, numerical simulation, combustion, kinetics of NOx generation, environmental compliance. Potential of modernization mutli-purpose engine family type CHN21/21 in terms of environmental compliance has been studied using numerical simulation of combustion process and kinetics of NOx generation, with a view to limit NOx emission to IMO Tier 2 specifications. Needed scope of engine modernization has been determined, along with range of adjustments affecting NOx generation. Feasibility of lowering emission from 13,26 g/kW�h to 7,34 g/kW�h without sacrificing fuel efficiency has been demonstrated.

FUEL. LUBRICANTS

Keywords: liquefied natural gas, modular unit, vortex tube, cryogenic tank. The article discusses design and technological issues involved in the development of a modular unit to produce motor fuel from natural gas extracted from a gas-main pipeline. The unit employs modern process of gas liquefaction in vortical apparatuses, based on reduction of main gas pressure to low level typical to industrial cryogenic tanks.

Keywords: motor oil, shell bearings, friction losses, viscosity model. A method is discussed to evaluate friction losses in heavy duty shell bearings lubricated with non-Newtonian motor oil. Rheological model of oil viscosity is offered that reflects viscosity dependence on oil temperature, pressure in thin film layer, shear and relaxation rates. Rheological model coefficients were derived based on tests. The article includes hydromechanical analysis of engine shell bearings.

ENGINE BUILDING NEWS

Keywords: reciprocating engines, emission compliance, control of combustion, exhaust aftertreatment. Modern engines must meet ever more restrictive emissions regulations, which encourages proactive development of clean air technologies. In nearest future (within 4�5 years) level of emissions has to be reduced by 80 % at least. Known and test-proven technologies can be split into �internal� ones (which implies improvements in fuel combustion) and �external� (which means exhaust gas aftertreatment). MAN Diesel & Turbo SE analyses clean air technologies to be selected as a basis for its future design strategies.