analysis of water injection into high-temperature mixture of ...

CHAPTER 4RESULTS AND DISCUSSIONThis chapter presents and discusses results obtained from simultaneousinvestigations of spark ignition engine models. Results were discussed to analyzeperformance parameters with variable of compression ratio range (8-12), equivalenceratio range (0.8-1.2) and engine speed range (1000-2500 RPM) which were doneusing MATLAB program. The model needs lots of parameters which aredistinguished such as engine geometries, fuel-air properties, and engine operatingcondition, in order to predict results. However, these were assumed in details ofknown parameters, mainly for the four stroke spark ignition without turbo or supercharger and Exhaust Gas Recirculation (EGR) system engine while the model wasdeveloped under no-load operating condition. An assumption on engine specificationto be used in the simulation is shown in Table 4-1 as below,TABLE 4-1 An assumption on engine specification for calculationEngine bore (m) 0.1Engine stroke (m) 0.08Half stroke to rod ratio (s/2l) 0.25Start of burning angle ( θ S)-35 (BTDC)Burn duration angle (Burn timing) (θb)60Engine surface temperature (K) 420Piston blow-by constant (s^-1) 0.8Residual fraction 0.1Start of compression angle-pi (BDC)Initial pressure (Pa) 100000Initial temperature (K) 350Initial volumeVBDCFuel typeGasolineAir dataJANAFMost of the discussions emphasize on the comparison of different molar waterinjection-fuel ratio ( XW) and water injection duration angle ( θ W) between waterinjection and without water injection system (normal) for comparison. Equationsforming are derived by considering the differential forms of crank angle ( θ ) changeswith time. So, water injection system can define to be the function of crank angle inthe studies. Table 4-2 defined the molar water injection for calculation ofmathematical models.