Dual fuel combustion system
The implementation of two-burner systems has recently been identified as a way to improve the thermal efficiency of internal combustion engines while simultaneously reducing their emissions. A Dual Fuel Combustion engine is used in a compression ignition (CI) engine to optimize the use of fast-burning or high-burning fuels. The implementation of dual fuel injection technology in these engines also makes it possible to improve the control of the combustion time by changing the ratio of the two fuels injected at the same time, and to use a higher combustion option than the two oil fields. Fuels that ignite well reduce the high pressure that normally occurs as a limiting factor. In an internal combustion engine (SI), implementing a dual ignition scheme works as another way to avoid engine knocking. The SI two-fuel engine relies on the simultaneous use of low-knock resistance and high-knock fuel to change the resistance of the fuel mixture to knock as needed. The dual fuel SI engine thus effectively prevents knocking without compromising engine performance.
Technology
The idea of a dual fuel engine has been around almost as long as the petrol (Otto) and diesel engine. Following the development of Nikolaus Otto’s combustion engine, the desire to improve combustion efficiency by increasing the compression of the engine led to the development of Rudolf Diesel’s compression ignition engine. Finally, the interest of controlling the ignition and regulating the combustion led Rudolf Diesel himself to design a two-burner engine and to develop its capacity in 1901. Today, the idea is used to promote the use of fuels such as gas from diesel fuel and the development of advanced combustion strategies that take advantage of the ability to improve the properties of the fuel mixture (by controlling the ratio between) . fuel injection) according to the operating conditions. Such implementation of the two-fuel injection scheme promises a significant increase in energy efficiency and a reduction in toxic emissions. This section aims to provide an overview of the development of two fuel engines by analyzing the specific history of technology and discussing current and past examples of two fuel engines in production. The following sections will discuss the ongoing dual fuel engine research and projected projects in the near and far future.
Dual Fuel Compression-Ignition Engines
Diesel or compression-ignition engines dominate the heavy-duty vehicle market due to their high efficiency and high torque generation capabilities. These engines require reactive fuel that automatically ignites at high pressure and temperature. This prevents fuel from being injected into the CI engine. Dual fuel engines provide a less efficient way to use fuel because they can use a secondary, reactive fuel to produce heat. Additionally, the dual fuel concept has also been explored as a way to reduce emissions. Conventional diesel emissions are controlled and are accompanied by high levels of nitrogen oxide (NOx) and particulate matter (PM). Nitrogen oxide from the high temperature in the cylinder promotes the combination of nitrogen (which is fresh air) and excess oxygen. During this time, particles or soot are produced in the fuel area as the hydrocarbon species combine. As such, a high number of equivalent areas can lead to the formation of soot and a high temperature of the area can lead to the formation of NOx, as shown in Figure 1. To avoid these problem areas, many engines Dual-fuel ICs attempt to operate under pre-amplified conditions. – mixing fuel with air and / or achieving in-cylinder stratification to achieve higher performance and lower emissions.
Conventional Dual Fuel CI Engines
Natural gas is more difficult to ignite than engine fuel, so it tends to burn more easily in the engine’s combustion chamber. On heavy-duty engines, natural gas requires an ignition source, so it is often injected into a port and directly injected with diesel fuel and serves as a fuel. – pilot. Orifice injected fuels are premixed with air and are quickly shown fire events that control the chemical kinetics of the fire reaction, but the fuel is injected directly and will mix with the air usually has a long fire action. This controls the time it takes for the air and fuel to mix properly. Since gasoline engines have one port and one direct fuel injection, they usually have a two-stage ignition system. The extent of combustion that occurs in the premixed and dispersed conditions will depend on the amount of each fuel used. Although it makes the combustion process more efficient, fuel injection can provide combustion that is not as efficient as gas from a CI engine.
Advanced Dual Fuel CI Engines
In order to make the engine go to higher performance, there has been a lot of research into complex ring types. Most of these advanced DF combustion schemes attempt to mix fuel with air to obtain a lighter and cleaner fuel, but can only be used at high temperatures. One strategy to extend the operating range of these processes is to use two fuels with different reactions at the same time to increase the ignition time and promote premixing in the higher operating range. This strategy is known as Reactivity Controlled Pressure Control (RCCI). In RCCI, low reactivity fuels such as gasoline are injected separately from high reactivity diesel fuel. The amount of each fuel can be different so that the combustion event can be delayed to provide enough mixing time and can achieve the desired shape of the combustion event.
Reactivity Controlled CI
The use of other fuels such as ethanol and natural gas under such RCCI operating conditions has also been shown to produce good results and appears to be beneficial to these processes. A study by Navistar, Argonne National Laboratory, and Wisconsin Engine Research Consultants found that using E85 as a low-performance fuel can help achieve higher loads and performance in RCCI. While gasoline and other diesel fuels achieved a BMEP of 11.6 bar and a brake thermal efficiency (BTE) of 43.6%, the use of E85 in diesel fuel helped to increase the performance to 19 bar BMEP and a BTE of 45.1%. A recent study by RWTH Aachen University and FEV GmbH showed that when using diesel and ethanol, high ethanol performance can be achieved under low load conditions and provides more heat. However, as the load increases, more diesel fuel is required to increase the number of cylinder pressures to an acceptable level.
