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A quasi-dimensional model for a direct injection diesel engine was developed based on experiments at Sandia National Laboratory. The Sandia researchers obtained images describing diesel spray evolution, spray mixing, premixed combustion, mixing controlled combustion, soot formation, and NOx formation. Dec [1] combined all of the available images to develop a conceptual diesel combustion model to describe diesel combustion from the start of injection up to the quasi-steady form of the jet. The end of injection behavior was left undescribed in this conceptual model because no clear image was available due to the chaotic behavior of diesel combustion. A conceptual end-of-injection diesel combustion behavior model was developed to capture diesel combustion throughout its life span. The compression, expansion, and gas exchange stages are modeled via zero-dimensional single zone calculations.

An infrared fiber optic instrumented spark plug probe has been used to measure the fuel concentration in the vicinity of the spark gap in a port injected gasoline fueled SI engine. The probe measured the fuel concentration spatially averaged over a distance of 6.3 mm near the spark plug for consecutive firing cycles. The crank angle resolution of the measurements was 2.5 degrees, for a temporal resolution of between 0.9 and 0.3 ms depending on the engine speed. Quantitative measurements of the fuel concentration in the pre-ignition regions of the engine cycle were obtained. Qualitative results are reported for unburned hydrocarbons in the post-combustion regions. The measurements were made in a single cylinder research engine over a range of speed, load, and stoichiometric conditions. Strong mixture inhomogeneities were measured during the intake stroke and the inhomogeneities decreased through the compression stroke.

Trucks operating in inter-modal (drayage) operation in and around port and rail terminals, are responsible for a large proportion of the emissions of NOX, which are problematic for the air quality of the Houston and Dallas/Ft. Worth metro areas. A standard test cycle, called the Texas Dray Truck Cycle, was developed to represent the operation of heavy-duty diesel trucks in dray operations. The test cycle reflects the substantial time spent at idle (~45%) and the high intensity of the on-road portions. This test cycle was then used in the SAE J1321 test protocol to evaluate the effect on fuel consumption and NOX emissions of retrofitting dray trucks with light-weight, low-rolling resistance wide-single tires. In on-track testing, a reduction in fuel consumption of 8.7% was seen, and NOX emissions were reduced by 3.8% with the wide single tires compared to the conventional tires.

Lean mixture combustion might be an important feature in the next generation of SI engines, while diluents (internal and external EGR) have already played a key role in the reductions of emissions and fuel consumption. Lean burn modeling is even more important for engine modeling tools which are sometimes used for new engine development. The effect of flame strain on flame speed is believed to be significant, especially under lean mixture conditions. Current quasi-dimensional engine models usually do not include flame strain effects and tend to predict burn rate which is too high under lean burn conditions. An attempt was made to model flame strain effects in quasi-dimensional SI engine models. The Ford model GESIM (stands for General Engine SIMulation) was used as the platform. A new strain rate model was developed with the Lewis number effect included.

Especially in crowded urban areas, light-duty vehicles often spend a great deal of time operating under idle conditions for which exhaust temperatures may be too low to maintain exhaust catalyst activity. This study investigated two methods of increasing Diesel exhaust temperature of a light-duty Diesel engine under idle conditions: post injection of fuel after TDC and intake throttling. For this particular study, EGR was not used. The engine operating parameters considered included three idle speeds of 800, 1100 and 1200 rpm, with the engine fully warmed up. Two rail pressures of 500 and 800 bar were studied with the injection strategy being the primary variable. The parameters measured included exhaust temperature, exhaust concentrations of NOx and HCs, as well as fuel consumption, IMEP and COV of IMEP. For the baseline idle conditions, manifold-out exhaust temperature was approximately 100 °C-105 °C.

This paper presents the results of an experimental investigation of the fuel-air mixing process in a port-fuel-injected, 4-valve, spark-ignited engine that was motored to simulate cold cranking and start-up conditions. An infrared fiber-optic instrumented spark plug probe was used to measure the local, crank angle resolved, fuel concentration in the vicinity of the spark gap of a single-cylinder research engine with a production head and fuel injector. The crank-angle resolved fuel concentrations were compared for various injection timings including open-intake-valve (OIV) and closed-intake-valve (CIV) injection, using federal certification gasoline. In addition, the effects of speed, intake manifold pressure, and injected fuel mass were examined.