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

Analytical and Experimental Investigation of Temperature-Swing Insulation on Engine Performance

“…These findings were further confirmed throughout the TACOM/Cummins adiabatic engine program (Sudhakar, 1984). (Siegla & Amann, 1984) speculated that the higher heat transfer due to compression of the air into the prechamber in their study would exacerbate the formation of NOx more than in the quiescent, direct-injection combustion chamber used in most heavy duty diesels, which was confirmed by an increase in NO measured with a pre-chamber diesel (Cole & Alkidas, 1985). (Morel, Fort, & Blumberg, 1985) and (Morel, Keribar, Blumberg, & Fort, 1986) predicted small increases in NOx with insulation, despite utilizing a directinjection combustion system.…”

“…It was emphasized that improvements in performance of highly insulated engines rely heavily on efficient turbomachinery (Wallace, Kao, Tarabad, Alexander, & Cole, 1984). (Siegla & Amann, 1984) performed simulations of the performance of a smaller, passenger-car-based indirect-injection diesel engine with thermal insulation. This study included part-load simulations to better cover the range of operation of engines in passenger vehicles and to take advantage of the proportionally higher heat losses at lower brake loads.…”

“…Literature reveals a spread in the analytical and experimental trends concerning soot and in-cylinder insulation. (Siegla & Amann, 1984) predicted an increase in soot emissions with lower heat rejection, possibly due to increased soot formation rates that are not countered by increased oxidation later in the cycle. It is conceivable that the separation into a relatively richer, hotter prechamber and cooler, higher oxygen content main chamber in Siegla's simulations biased the net soot balance towards the generation mechanism, while soot oxidation was relatively suppressed by lower main chamber temperatures.…”

“…Radiation is strongest from soot and other combustion particulates that resemble "black bodies", which have an emissivity coefficient close to unity. (Siegla & Amann, 1984) note radiation becomes much more prominent in insulated engines, up to 25% of the total heat loss from 10%. They state that hotter wall temperatures will not have an impact on radiation, which for practical purposes is true since the radiation from the gas to the walls is only dependent on gas temperature.…”

An Air‐gap Insulated Piston

“…A reduction of the heat loss during the power stroke should result in a direct improvement in power output and specific fuel consumption, although the benefits are not as great as might be imagined since the hotter combustion chamber also causes increased compression work and reduced volumetric efficiency (2,3,4). Low heat loss engines do, however, produce a substantial increase in exhaust temperature and the extra energy available can be used to advantage in the turbocharger or further utilised by a power turbine geared to the crankshaft (4).…”