Mise au point et utilisation d'une simulation sur ordinateur pour l'etude des performances et des transferts de chaleur d'un moteur diesel turbocompound

Development and Use of a Computer Simulation of the Turbocompounded Diesel System for Engine Performance and Component Heat Transfer Studies

This paper presents a general overview about the previous research efforts into Low Heat Rejection Engine (LHRE) concept. The purpose of this paper is to explain the effect of insulation on engine performance, heat transfer characteristics, combustion and emission characteristics. Many researchers have carried out a large number of studies on LHRE concept. Some of them are experimental work and many are theoretical studies. In the case of LHR engines almost all theoretical studies predict improved performance but many experimental studies show different picture. This paper analyzes the reason for this deviation. The operating conditions, under which the experimental and simulation studies are carried out, have been clearly discussed. The factors, which affect thermal efficiency, combustion, and exhaust emissions in LHR engine, are deduced and their influences discussed. Effect of fuel injection characteristics on LHR engine performance is also reviewed. It is concluded that much more research is needed to overcome the practical problems before LHR engines can be put into production.

Low Heat Rejection Engines – An Overview

Experimental investigation is carried out under different loading conditions in a three cylinder diesel engine with its piston crown coated with Yttria Stabilized Zirconia (YSZ) to understand the influence of the thermal barrier coating (TBC) on performance and emission characteristics in comparison with baseline engine characteristics. YSZ is chosen as the candidate material for coating the piston crown because of its desirable physical properties such as high coefficient of thermal expansion, low thermal conductivity, high Poisson’s ratio, and stable phase structure at higher temperature conditions. For the measurement of emission characteristics, ISO 8178-4 “C1” 8 Mode testing cycle procedure is followed. Experimental results revealed that the heat loss to the cooling water is reduced up to 5–10% and the thermal efficiency is increased by 3–5% with reduction of brake specific fuel consumption by up to 28.29%. Experimental results also revealed that Hydro carbon (HC) emission is reduced up to 35.17%, carbon monoxide (CO) by up to 2.72% and Carbon di-oxide (CO 2 ) emission is increased by up to 5.6%.

Investigation on effect of Yttria Stabilized Zirconia coated piston crown on performance and emission characteristics of a diesel engine

Eliminating the conventional liquid cooling system of a diesel engine to conserve energy normally rejected to that heat sink offers promise as a means for improving fuel economy. Such low-heat-rejection (LHR) diesels have generally been advanced for heavy-duty vehicles. In this study, application of the concept is analyzed for a light-duty indirect-injection diesel of the type used in passenger cars. The naturally aspirated LHR diesel is found to offer no fuel economy advantage, principally because of the deteriorated volumetric efficiency arising from hot cylinder walls. It is found that most of the energy conserved by deleting the cooling system is diverted to the exhaust gas. Methods examined for recovering the lost volumetric efficiency and/or harnessing the increased energy content of the exhaust include supercharging, adding a bottoming cycle, and combining the diesel with turbomachinery. The latter option is judged superior for the passenger-car application.

Diesel for Passenger-Car Application Exploratory Study of the Low-Heat-Rejection Diesel for Passenger-Car Application

Innovative Research Trends in the Application of Thermal Barrier Metal Coating in Internal Combustion Engines

The paper describes the results of a detailed cycle analysis applied to a high output 6 cylinder truck diesel engine: 1) conventional form; 2) with a uniformly distributed layer of silicon nitride giving approximately isothermal wall conditions; and 3) with adiabatic wall conditions. For case (1) the benefits are largely limited to increased exhaust enthalpy, suggesting the desirability of turbocompounding. Case (2) gives marked improvement in cycle efficiency as well as raised exhaust enthalpy. Paper number 790823.

R.J.B. Way

Papers

Effect of partial suppression of heat loss to coolant on the high output diesel engine cycle