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The objective of this study was to observe and attempt to understand the effects of equivalence ratio and simulated exhaust gas recirculation (EGR) on the exhaust emissions and performance of a L-head single cylinder utility engine. In order to isolate these effects and limit the confounding influences caused by poor fuel mixture preparation and/or vaporization produced by the carburetor/intake port combination, the engine was operated on a premixed propane/air mixture. To simulate the effects of EGR, a homogeneous mixture of propane, air, and nitrogen was used. Engine measurements were obtained at the operating conditions specified by the California Air Resources Board (CARB) Raw Gas Method Test Procedure. Measurements included exhaust emissions levels of HC, CO, and NOx, and engine pressure data.

A method of calculating mass burning rates for a single cylinder spark-ignition combustion engine based on experimentally obtained pressure-time diagrams was used to analyze the effects of fuel-air ratio, engine speed, spark timing, load, and cyclic cylinder pressure variations on mass burning rates and engine output. A study of the effects on mass burning rates by cyclic pressure changes showed the low pressure cycles were initially slow burning cycles. Although large cyclic cylinder pressure variations existed in the data the cyclic variations in imep were relatively small.

A single cylinder TACOM-LABECO open chamber diesel engine with a special research head, which incorporates an American Bosch Electronic Fuel Injection System, was used to study the effects of air swirl, injection pressure and nozzle geometry on exhaust particulates, NOx emissions, ignition delay, heat release and local heat flux measured at two positions on the head. Air swirl was varied from 0.8 to 4.5 swirl ratio by use of a shrouded intake valve. Peak injection pressure was varied from 35-114 MPa. Five different nozzle geometries were tested. All data were taken at a fixed engine operating condition of 2000 rpm and 0.5 equivalence ratio with an inlet pressure of 1.5 atm and nominal inlet temperature of 340°K.

The multicylinder turbocharged engine was simulated by assuming each cylinder undergoes the same thermodynamic cycle. The model for the cylinder includes instantaneous heat transfer, homogeneous combustion burning rates, and a scavenging model which allows any intermediate mode between perfect scavenging and complete mixing. Metal surface temperatures are calculated by use of cyclic energy balances. The air receiver pressure is assumed constant and the exhaust manifold pressure is calculated by use of a filling and emptying process. The turbocharger turbine is analyzed on a quasi-steady basis with given mass flow-expansion ratio characteristics and efficiency-velocity ratio curves. Steady flow is assumed and experimental performance was used to model the compressor. Engine and turbocharger operating conditions are adjusted in the program until an energy balance is attained between the engine and the turbocharger.

A computer program which rapidly calculates the equilibrium mole fractions and the partial derivatives of the mole fractions with respect to temperature, pressure and equivalence ratio for the products of combustion of any hydrocarbon fuel and air is described. A subroutine is also given which calculates the gas constant, enthalpy, internal energy and the partial derivatives of these with respect to temperature, pressure and equivalence ratio. Some examples of the uses of the programs are also given.