1 Introduction
In recent years, it has become increasingly important for many industries to make use of dual-fuel engines as a means of reducing their operation costs. Dual fuel engines are a hybrid system of two types of power sources, namely diesel and natural gas. In this system, one fuel acts as the main fuel and is used for the majority of your operation, while the other serves as a reserve.
These engines can be custom designed to suit a variety of applications, allowing a cost effective and efficient solution for many different industries. For this reason, it is important to have standards and regulations that define the minimum requirements for these engines. This paper introduces the national standard of China, QC/T 694-2002, related to diesel and compressed natural gas dual fuel engines, by discussing its technical requirements and providing a brief overview of developments related to their design and establishment.
2 Overview of Standard
QC/T 694-2002 is a national standard of the People’s Republic of China which relates to technical requirements of diesel and compressed natural gas dual fuel engines. This standard is applicable to the dual fuel engines used in vehicles, stationary engines, cogeneration systems and marine engines.
The requirements of QC/T 694-2002 are divided into 5 parts: general requirements, engine requirements, fuel system requirements, fuel injection system requirements and starting system requirements.
The first part, general requirements, provides general stipulations for the dual fuel engine such as the type and capacity of the engine, the purpose of use, the working environment in which the engine will operate and its performance testing requirements.
The second part, engine requirements, provides more detailed information related to the general requirements such as the structure of the engine, the operating parameters, the lubrication system and the cooling system.
The third part, fuel system requirements, covers the requirements related to the components of the dual fuel system such as the fuel injection system, fuel supply systems and storage.
The fourth part, fuel injection system requirements, addresses the requirements related to the fuel injection system, including informaion such as the types of injectors and the required injection pressure.
The fifth part, starting system requirements, outlines the requirements for the starting system of the engine, including the minimum starting voltage and current, and the cold start system.
This standard also outlines the necessary procedures for performance testing and inspection, as well as stipulations on the methods for packing,marking, and transport.
3 Development in Dual Fuel Engines
3.1 Design and Analysis
Since the establishment of QC/T 694-2002, a great deal of research and development has been done on the design and analysis of dual fuel engines.
Much research has been devoted to the optimization of the fuel injection strategies. Amongst the strategies studied areVariable Advance Injection Variable Injection Duration (VAID), Multi-Port Interval Injection (MPI), Variable Injection Advance Injection, as well as other strategies research.
The study of heat transfer and fluid flow in the fuel systems of dual fuel engines has been also of particular concern. Research on this matter has been done to better understand the flow patterns and the details of the combustion processes. This research is fundamental for improving the efficiency and the performance of these engines.
3.2 Combustion
Another important development in the field of dual fuel engines pertains to the combustion processes. Research has been done to study the influence of fuel composition and injection strategies on the overall combustion efficiency. By understanding better the details of the combustion process, it is possible to adjust the injection strategies and fuel mixtures to maximize the efficiency of the engine. Various studies have been conducted on the combustion characteristics of different fuel mixtures and their combustion processes, as well as their emissions.
3.3 Emissions
The emissions of dual fuel engines is another area of research that has been examined in great detail. Studies have been done to examine the factors that can affect emissions, and mathematical models have been developed to predict emissions. Other research have been done to study the effects of fuel mixtures and other parameters on engine emissions. This research is essential in understanding the ways to reduce emissions from dual fuel engines and thus meet the stricter emission standards that are currently being put in place.
4 Conclusion
Dual fuel engines offer many advantages over traditional diesel engines, including cost savings and more efficient operation. For these engines to operate properly and safely, regulation and standards are important. QC/T 694-2002 is a national standard of the People’s Republic of China that sets forth the technical requirements for diesel and compressed natural gas dual fuel engines.
Since this standard was established in 2002, significant research and development has been done on the design and analysis of dual fuel engines as well as their combustion and emissions. Research on these topics continues and new advancements are made every day. This research is fundamental for improving the efficiency and the performance of these engines.
