Modification Of Compressed Natural Gas Engine And Its Performance Study

Double pressures that petrol resource shortage and environment pollution becomemore and more serious, have encouraged the exploring and developing of new fuel forinternal combustion engine. Natural gas is rich all over world, and its cost is low, which isan idea fuel for the engine.Performance changing regulations of the engine, which is fueled with compressednatural gas, will be researched and analyzed. Firstly, the basic structure and operationprinciple of CNG engine are summarized. From the point of analyzing physical andchemical properties of natural gas, having a diesel engine modified to form a natural gasengine, and supplying system, intake system, ignition system, combustion system andpost-processing system are designed for natural gas engine, which is to meet the usingrequirements of natural gas applying on the engine. Then on the basis of calibrating forbasic ignition advance angle and volumetric efficiency of natural gas engine, basic controlstrategy that closing loop control is adopted at part load while open loop control is adoptedat full load is put forward. Finally, engine bench test is done on the natural gas engine,velocity performance, load performance and universal performance being researched, andthe performance of natural gas engine is comprehensively evaluated. The mainachievements of the paper are as follows.1) Research is carried out on the distribution of natural gas resources, analyzing thedevelopment situation of natural gas engine and the significance of developing natural gasengine. The basic structure and basic operation principle of CNG engine are reviewed, andthe concept of main performance indicators for engine is described.2) Based on analyzing physical and chemical properties of natural gas, JL4JB1dieselengine is chosen as the original engine, to modify the CNG engine. And fuel supplyingsystem, intake system, ignition system, combustion system and post-processing system aredesigned.3) Basic controlling strategy of natural gas engine is determined, and basic ignitionadvance angle, volumetric efficiency are calibrated4) The power performance, load performance and universal performance of the naturalgas engine are tested on the bench. And comprehensive performance of natural gas engineis reviewed.From the main achievements outlined above, conclusion can be drawn that thechanging process of natural gas engine is reasonable, and CNG engine is operatedsuccessfully. The comprehensive performance of the natural gas engine is strengthened.