| abstract |
A low emission power generating apparatus which comprises a modified two-stroke diesel engine component and a modified turbocharger component which has a relatively low aspect ratio. The diesel engine component is a modification of a conventional two-stroke diesel engine design and includes an exhaust valve cam of unique design that has a cam profile which results in a later than-normal exhaust valve opening and an earlier-than-normal valve closing so that the time during which the exhaust valve remains open is shorter than normal, thereby causing a substantially greater volume of residual gases to remain in the combustion chamber following the scavenge stroke. This increase in the volume of the residual exhaust gases within the chamber leads to an increase in compression temperature and effectively increases the compression ratio and consequently the compression pressure. Because of the heat absorption capacity of these residual exhaust gases, the exhaust gases remaining in the chamber following the scavenge stroke tend to absorb combustion heat and thereby effectively reduce the peak combustion temperature. This reduction in peak combustion temperature advantageously results in the lower than normal formation of nitrogen oxide (NOx) and, therefore, allows advancement of the injection timing, while still maintaining the NOx emissions coming from the engine lower than those legislatively mandated. Advantageously, the advance in injection timing, which increases NOx emissions, by definition has the effect of also reducing particulate matter emissions. Thus, by increasing the volume of residual exhaust gases within the cylinder, substantial particulate matter emission reductions can be achieved, while at the same time maintaining NOx emissions well below mandated limits. The modified turbocharger component provides an additional charge of oxygen-rich air into the combustion chamber which effectively increases the compression pressure, which, in turn, leads to an earlier start of combustion because of the combustible mixture reaching its auto-ignition temperature at an earlier point in the cycle. This phenomenon leads to more thorough combustion of the fuel and also generally leads to higher exhaust temperatures. Higher exhaust temperatures, in turn, lead to a greater oxidation rate of the soluble organic fraction thus lowering the level of emission from the engine of undesirable particulate matter. |