IPTEK, Journal of Engineering, Vol. 5, No. 2, 2019(eISSN: 2337-8530) 23 Effects of Pilot Injection Timing on the Engine Performance of a Diesel Dual Fuel Engine Jose da Silva 1 , Dori Yuvenda 2 , Bambang Sudarmanta 1 AbstractThe combustion process in dual fuel diesel engines occurs sequentially starting with premix burning. The premix burning starts with the ignition delay process. The presence of CNG causes the ignition delay process to become longer, thereby reducing engine performance and increasing emissions on dual fuel diesel engines. This study uses diesel engine type Diamond DI 800 with dual fuel indirect injection model system. The method used a variation of diesel pilot injection timing 110 CA, 130 CA, 150 CA, 170 and 190 CA BTDC. Testing is done with a constant engine speed of 1500 rpm and loading 500 to 3000 watts with 500-watt intervals. The results show that by advancing the diesel pilot injection timing where brake horsepower and the average effective pressure between single fuel and dual fuel is not too far as the current and voltage changes generated by the generator are not too small. While optimal thermal efficiency increased by 4.11%, while CO and HC emissions decreased respectively by 10.85% and 8.28% at occurred at the pilot injection timing 170 CA BTDC but still under the single fuel engine. Keywords Diesel Pilot Injection Timing, Thermal Efficiency, Carbon Monoxide, Hydrocarbon I. INTRODUCTION 1 he technology that promises to be used in internal combustion engines is dual fuel or dual fuel systems. Diesel fuel diesel engine is a diesel engine that added fuel gas in the intake manifold or directly to the combustion chamber and ignition is carried out by diesel spray [1], [2]. The combustion process in the Diesel Dual Fuel (DDF) engine occurs sequentially wherein the first stage there is premix burning of the pilot fuel. In the premix combustion process, the pilot begins with an ignition delay process. Ignition delay is the time from the start of the initial period of diesel injection (start of injection) to the start of combustion (start of combustion). Stage ignition delay there are two parts namely; first physical delay, where this period occurs atomization, evaporation, mixing between fuel and air. Second, chemical delay where this period of chemical reactions start slowly and then accelerate the formation of fire spots. Currently, the technology of fuel entry systems developed in DDF engines is a mixer, low pressure and high pressure [3]. Theoretically, the more efficient type of dual fuel system used is a Low Pressure (LP) model, because reducing CNG is wasted. Where the CNG is supplied only after the suction valve is opened and the exhaust valve is closed so that gas fuel supply is more efficient. Also, this type also requires a cheaper cost than other types. The low-pressure system using diesel and CNG fuels has decreased engine performance by 65% average thermal efficiency reduction against single fuel [4], [5]. The pilot injection timing will effect on engine performance, combustion process, cylinder pressure, HRR, thermal efficiency and emission formation. 1 Jose da Silva, and Bambang Sudarmanta are with Department of Mechanical Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia. E-mail: josepayaharanomoko@gmail.com; bsudarmanta@gmail.com. 2 Dori Yuvenda is with Department of Automotive Engineering, Universitas Negeri Padang, Padang, 25171, Indonesia. E-mail: doriyuvenda@ft.unp.ac.id. To improve engine performance by advancing diesel pilot injection time can affect the speed of burning diffusion slower 45% compared to premix burning stage. Taken and the rate of heat release increased and a significant decrease in CO and HC emissions and increase NOx increases [6], [7]. Based on the description and the above research can be concluded that by advancing the diesel pilot injection timing can affect the ignition delay thus affecting engine performance. II. METHOD The test is done by an experimental method on Diamond DI 800 diesel engine, with the main shaft which has been directly coupled with an electric generator, figure 1. This machine will be modified into dual fuel by using diesel fuel and natural gas type compressed natural gas (CNG). The test was conducted into 2 (two) groups, namely diesel engine using single fuel with diesel fuel as a control group, and diesel engine using dual fuel system with combination fuel of diesel fuel and CNG as a test group. To get combustion performance when diesel pilot injection is done variation at the angle or diesel pilot injection timing by adding a shim on packing injection pump holder. Lights as loading on the machine. The lamp consists of incandescent lamps as much as three pieces with power consumption of each lamp of 500 Watt. The lights are arranged in parallel on a board with each lamp equipped with a contact for setting the light load. The engine modification process and the whole series of tests were conducted at the Fuel Laboratory and Energy System, Department of Mechanical Engineering, Institut Teknologi Sepuluh Nopember Surabaya. Thus the authors conducted an experimental study on diesel diamond type DI 800 diesel engine, one cylinder, which is operated by dual fuel solar-gas CNG. The method used is setting diesel pilot injection time of 110CA, 130CA, 150CA, 170CA and 190CA BTDC under T brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by IPTEK The Journal of Engineering