Experiment On The Influences Of CVS Test Bench And Test Parameters On Heavy-Duty Diesel Engine Performance

Engine parameters and CVS parameters have strong influences on the performance of diesel engine.Based on the emission regulations,this subject uses a CNHTC diesel engine to do several tests to explore the effects of these parameters.Through the experimental results,the influences of engine and CVS parameters on engine performance are analyzed and studied.These results sum up the optimized conditions of engine and CVS system for engine tests.The main research contents are as follows:Firstly,this paper made a brief introduction on emission regulations,forming mechanism,influence factors and measurement methods.According to the requirements of engine tests,the diesel engine test bench was built.Secondly,the influences of engine parameters were investigated.Several key parameters,such as intake air pressure and humidity,intercooler temperature and pressure loss,exhaust back pressure,were adjusted and tested.These results show the influences on the performace of diesel engine.PM is very sensitive to the engine condition changes.THC,CO are sensitive to intercooler condition changes.NOx is almost stable when engine condition changes.The test engine can get best performance with-2kPa intake air pressure,50%intake air humidity,15kPa exhaust back pressure,50℃ intercooler temperature and 7.5kPa intercooler pressure loss.Thirdly,the influences of CVS system parameters were investigated.These test results show the best condition of CVS system for emission test.By changing CVS flow rate and second sample flow rate and measuring the PM of these tests,the influences of dilution system parameters on emission test were explored.These results show that PM result is very sensitive to CVS parameters.Under the emission regulations,choosing smaller CVS flow rate and larger second sample flow rate achieves better PM result.Filter weighting can reduce the influences of different CVS parameters.