Effect of the Cetane Number Improving Additive on Combustion, Performance, and Emissions of a DI Diesel Engine Operating on JP-8 Fuel

Abstract

The article presents the bench test results of a fully instrumented, four cylinder, naturally aspirated, (60 kW) direct injection (DI) diesel engine running on the normal (class C) diesel fuel (DF) and aviation-turbine (JP-8) fuel. The article addresses changes in engine performance and exhaust emissions resulting from the replacement of commercial diesel fuel with JP-8 fuel. Investigation and comparison of the effects of the cetane number improving additive on the autoignition delay, maximum heat release rate, maximum in-cylinder pressure, performance efficiency of an engine, and exhaust emissions were provided for sound analysis of the test results. The series of engine tests were conducted running alternately on the normal diesel fuel, JP-8 fuel, and JP-8 treated with 0.04, 0.08, 0.12, 0.16, and 0.24 vol% of 2-ethylhexyl nitrate. Studies on the operating characteristics of an engine were carried out for 15–10%, 50 and 100% loads, and the two ranges of speed: 1,400 revolutions per minute (rpm), at which maximum torque occurs, and a rated speed of 2,200 rpm. Use of JP-8 fuel suggested fuel energy savings and ecological benefits for medium (50%) and full (100%) loads mainly when running at a low speed of 1,400 rpm. Autoignition delay, maximum heat release rate, maximum in-cylinder pressure, and nitrogen oxide (NO x ) emissions decreased; however, the carbon monoxide (CO), hydrocarbon (HC) emissions, and the smoke opacity of the exhaust increased to a certain extent responding to the addition of 2-ethylhexyl nitrate to the JP-8 fuel. The brake-specific fuel consumption and brake thermal efficiency of a fully (100%) loaded engine changed little when running on treated JP-8-12 fuel at a rated speed of 2,200 rpm. Analysis of the test results revealed that the cetane number improving additive can be considered as an effective but not the only measure to be applied for an intended use of aviation-turbine JP-8 fuel in ground-based diesel engines.