Experimental investigation of the performance and exhaust emissions of a swirl chamber diesel engine using JP-8 aviation fuel

Abstract

SUMMARYAn experimental study is conducted to evaluate the use of JP-8 aviation fuel as a full substitute for diesel fuel in a Ricardo E-6 high-speed naturally-aspirated four-stroke experimental engine having a swirl combustion chamber. The study covers a wide range of engine load and speed operating conditions, comprising measurements of cylinder pressure diagrams, high-pressure fuel pipe pressures, exhaust gas temperatures, fuel consumptions, exhaust smokiness and exhaust gas emissions (nitrogen oxides, unburned hydrocarbons and carbon monoxide). Processing of the measurements provides important performance parameters such as maximum combustion pressure, dynamic injection timing, ignition delay, combustion irregularity and knocking tendency. The differences in the measured performance and exhaust emission parameters are determined for engine operation with JP-8 fuel, against baseline engine operation using diesel fuel. The study shows that the exhaust emission levels are not much different for operation with the two fuels. On the contrary, operation with JP-8 fuel increases combustion pressures, combustion intensity and irregularity. This is caused mainly by high pressure fluctuations present in the fuel injection system due to the different physical properties of JP-8 fuel (compared to diesel fuel), which totally change the injection characteristics. Retardation of the static injection timing is one means of improving this situation, while using the same fuel injection equipment.

Comparative Environmental Evaluation of JP-8 and Diesel Fuels Burned in Direct Injection (DI) or Indirect Injection (IDI) Diesel Engines and in a Laboratory Furnace

“…Again, as the load (torque output) of the IDI engine was increased from 50% to 100% of the full engine load, BSFC decreased monotonically at all speeds (low, medium, high) for both fuels. No clear trend in BSFC was observed with the fuel type, as the BSFC of JP-8 was higher at low speeds and low loads, and at high speeds, but it was lower than that of diesel oil at medium speeds . The maximum cylinder pressures were almost independent of the load, and, in most cases, they decreased with engine speed.…”

“…Indirect Injection (IDI) Diesel Engine Emissions. As in the case of the DI engine, exhaust soot emissions increased as the engine load increased, because both the local and global equivalence ratios increased; however, no clear trend with engine speed was observed . At most power settings, the soot emissions from JP-8 were higher.…”

“…No clear trend in BSFC was observed with the fuel type, as the BSFC of JP-8 was higher at low speeds and low loads, and at high speeds, but it was lower than that of diesel oil at medium speeds. 27 The maximum cylinder pressures were almost independent of the load, and, in most cases, they decreased with engine speed. JP-8 combustion resulted in higher maximum pressures.…”

“…33 Indirect Injection (IDI) Diesel Engine Operating Characteristics and Performance. Data for such an engine have been published in ref 27, where detailed explanations are given; herein, results are only summarized. Again, as the load (torque output) of the IDI engine was increased from 50% to 100% of the full engine load, BSFC decreased monotonically at all speeds (low, medium, high) for both fuels.…”

“…They were attributed to pressure fluctuations in the fuel pipe, because the injection pump delivery was not optimized for the lower density and viscosity of the JP-8 fuel. 27 Ignition delay decreased as the load increased, as higher equivalence ratios rendered the mixture easier to ignite. Again, the JP-8 fuel exhibited lengthier ignition delays in most cases.…”