Application Research On Diesel-LNG Dual Fuel Engine Based On Electric Control Injection System

With the rapid development of automobile industry, the quality of people’s living standard have been greatly improved. Meanwhile, the problem of environmental pollution and shortage of energy has become increasingly serious. Currently, diesel engines with mechanical pump design are usually of high fuel consumption and bad emissions. Liquefied natural gas (LNG), as a good alternative engine fuel, can alleviate this contradiction. Diesel-natural gas dual fuel engine has been receiving more and more attention for its advantages such as good emissions characteristics, convenient retrofitting and flexibility in use. This paper researched and developed dual fuel retrofitting technology on the CA4113Z diesel engine. The study concentrated on improving the fuel economy and avoiding high exhaust and engine detonation without reducing the engine’s power performance. The main contents and conclusions were as follows:1. An overall scheme of the diesel-LNG dual fuel system was designed. A natural gas jet moment judgment method was proposed based on injection pipe pressure. A plunger-type mixer with simple and rational structure was created. To precisely reflect the throttle position, this paper devised a throttle position detection device included rotary potentiometer and fuel adjustment lever. A fuel saving control strategy capable of precisely controlling the position of injection pump rack was proposed.2. The theoretical calculation of the injection quantity in different natural gas replacement rate in different engine conditions was studied. In order to provide a scientific basis for the initial natural gas MAP data, this paper verified the natural gas injection quantity in different engine conditions in theory based on the bench test data of single fuel engine. A natural gas injector flow calibration test scheme was proposed. Also, the study explored the flow characteristics of injector.3. A dual-fuel online calibration software was developed. This software, having a good user interface, diverse functionalities and operational stability, played an important role in calibration work.4. An arrangement for a dual-fuel test scheme was proposed. The results indicated that the power performance decrease was less than 5% compared to single-fuel mode; Fuel cost was saved by 25% and the general emissions performance improved markedly in dual-fuel mode under the medium and high load conditions.