MIT OpenCourseWare http ocw mit edu 2 61 Internal Combustion Engines Spring 2008 For information about citing these materials or our Terms of Use visit http ocw mit edu terms 2 61 Internal Combustion Engine Engine Laboratory Exercise Lab report due 4 24 08 Spring 2008 OBJECTIVE The objective of the laboratory is to provide the students with some familiarity to how does a real engine behave to operate the engine and the exhaust gas emissions measurement system and to acquire and explain the engine data ORGANIZATION The class will be divided into a Tuesday 4 15 08 group and a Thursday 4 17 08 group Each group will work on the engine for one afternoon from 1 to 2 30 pm The data gathering is a team effort with the raw data to be shared by all members of the group Each student however has to write a lab report individually based on independent analysis of the raw data The report title will be The Load Speed Dependence of SI Engine Emission Behaviors The data presented in the report should have been reduced to meaningful results It is important that the results be explained according to your understanding of the physical phenomena involved LABORATORY MEASUREMENTS The engine is a 4 cylinder 4 valve per cylinder production spark ignition engine The engine is the DaimlerChrysler DCX 2 4L engine which powers the Minivan The specifications are Bore Stroke Compression Ratio Connecting Rod Length Rated Power Peak Torque Firing Order 87 5 mm 101 0 mm 9 4 136 5 mm 117 KW 5000 rpm 227 n m 4000 rpm 1 3 4 2 IVO IVC EVO EVC 1o BTC 51o ABC 52o BBC 8o ATC The fuel used is Certification gasoline HF437 the fuel properties can be found on the course web site The fuel is injected in the intake port The equivalence ratio is changed by varying the injection duration which is controlled by the DaimlerChrysler ECU using the information from the Exhaust Gas Oxygen EGO sensor at the exhaust Note that this sensor gives only an on off type of signal therefore an additional Universal Exhaust Gas Oxygen UEGO sensor is used to read the air fuel ratio Also note that the ECU modulates the equivalence ratio at 2 Hz in the range of 0 975 to 1 025 the UEGO displays the averaged value a At 1600 rpm 46 N m brake torque operation check that the emission measurements are consistent by determining the equivalence ratio from a carbon balance and compare that with the UEGO sensor output Note that this is the standard light load condition employed by DaimlerChrysler to check out all their engines b Produce the Engine Out emission maps for the engine for the following and explain the observed trends You should use brake specific values which are the values normalized by the energy output of the engine Brake specific CO emission Brake specific HC emissions Brake specific NO emission Brake specific fuel consumption based on carbon balance Note the map is a contour plot of the specific quantities as a function of the engine brake torque and rpm It should include points on the WOT line and have data points reasonably spaced Roughly a 4x4 data matrix will suffice You could plot the contours by hand using interpolation It is not necessary to use a computer program to plot these contours Point out the features on these plots and explain why the engine exhibits such behaviors