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Technical Paper

Thermal Loading of the Cylinder Head of a Divided - Chamber Diesel Engine

Time-averaged combustion chamber surface temperatures and surface heat fluxes were measured at three locations (one in the antechamber and two in the main chamber) on the head of a single-cylinder, divided-chamber diesel engine. In general the surface temperature and heat flux were found to increase with increasing engine speed, fuel-air ratio and intake-air temperature, decreasing coolant temperature and advancing combustion timing. At motored conditions the highest heat flux was at the antechamber location. This was caused by the high swirl flows present in the antechamber. In contrast, at all other conditions the highest heat flux was measured at the location in the main chamber near the valves. This was attributed to the convective action of the high-temperature stream of combustion gases exiting the antechamber during the expansion stroke. Lastly, the local surface heat flux measurements were correlated in terms of the air and fuel consumption rates of the engine.
Technical Paper

Gaseous and Particulate Emissions from a Single - Cylinder Divided-Chamber Diesel Engine

In this study, the effects of engine speed, air-fuel ratio, combustion timing, intake-air temperature, and coolant and oil temperature on exhaust gaseous emissions (nitric oxide, carbon monoxide and hydrocarbons) and particulate emissions (particulates, volatiles and smoke) were investigated in a single-cylinder, divided-chamber diesel engine. In addition, the trade-off behavior of the pollutants was investigated. To aid in the interpretation of the experimental findings, a single-chamber, single-zone heat release model utilizing experimental main-chamber pressure-time data was employed. The large increase in nitric oxide emission index caused either by increasing the air-fuel ratio or by advancing the combustion timing is attributed to the proportionally larger amounts of fuel that burn at near TDC conditions.
Technical Paper

Inventory of Heat Losses for a Divided–Chamber Diesel Engine

A series of experiments was performed to characterize the various components of heat losses from a single-cylinder divided-chamber diesel engine. This investigation included studies (a) to determine the contribution of piston friction to the heat rejection to the coolant, (b) to measure the amount of heat rejected through the exhaust port to the coolant and (c) to evaluate the heat losses to the surroundings. The above measurements were used to evaluate the total heat losses to the combustion chamber by the working fluid during the engine cycle. These losses were then compared to the heat losses during the closed portion of the cycle (intake valve closing to exhaust valve opening) that were computed with the aid of pressure-time data.
Technical Paper

The Effects of Coolant Temperature on the Performance and Emissions of a Single-Cylinder Divided-Chamber Diesel Engine

Comparative experiments were performed on an experimental divided-chamber diesel engine for three coolant conditions: baseline (water at 82°C), high coolant temperature (glycol at 120°C) and a differential cooling condition where the antechamber was kept cold (water at 20°C) and the main chamber was kept hot (glycol at 120°C). High-temperature cooling was found to provide a significant brake-specific-fuel-consumption advantage at low-speed and low-load conditions and at very retarded combustion-timing conditions. In general, high coolant temperature caused an increase in hydrocarbon (HC) emissions. Lowering the antechamber surface temperature at the low-speed conditions was found to cause an increase in gaseous emissions and a reduction in smoke and particulate emissions.
Technical Paper

The Distribution of Heat Rejection from a Single-Cylinder Divided-Chamber Diesel Engine

The effects of engine speed, load, and injection timing on the distribution of heat rejection to the coolant were examined in a single-cylinder divided-chamber diesel engine. The cooling system was separated into four zones: cylinder liner, intake port, exhaust port, and ante-chamber. The fractions of the total amount of heat rejected to the coolant from the four cooling zones were moderately affected by load and injection timing, but were not affected by engine speed. Typical values of these fractions are: cylinder liner - 53%, exhaust port - 22%, antechamber -18%, and intake port - 7%. The total amount of heat rejected to the coolant increased with engine speed and load; injection timing had a smaller but significant effect. Finally, the heat rejected to each cooling zone was correlated with the rate of fuel consumption.