Turbocharging a Low BMEP Pump Scavenged Engine
Increasingly stringent emissions standards are continually driving the natural gas industry to seek cost-effective methods of reducing environmentally harmful pollutants. It is widely known that the two significant contributors to air pollution are NOx and CO. NOx formation is exponentially dependent on temperature and time. The combustion temperatures which provide the environment where oxides of nitrogen form are directly linked to the equivalence ratio. CO formation is dependent on combustion efficiency as a function of mixing, ignition energy, cylinder temperature and, therefore, equivalence ratio. Thus, engine operation under a leaner equivalence (air/fuel) ratio effectively reducing combustion temperatures can decrease NOx and CO production. To meet these desired operating conditions, a turbocharger in combination with enhanced mixing nozzles were installed directly to a Worthington LTC 2-stroke, spark ignition, direct injection engine. Turbocharger installation in combination with modified port geometry allows for a higher air manifold pressure increasing the trapped air/fuel ratio as well as increasing the engine air through flow improving cylinder scavenging. By supplying fuel at injection speeds greater than Mach and boosting engine air through flow, NOx and CO emissions were reduced – but not without a few technical challenges. Low BMEP internal combustion engines such as the Worthington LTC have less energy available due to their low operating efficiency. This reduces the available energy within the exhaust stream and therefore reduces the available work delivered to the turbocharger turbine and compressor. To account for and overcome this challenge, the design team implemented modifications to the piston, intake port and exhaust port geometry. Utilizing parametric modeling and computational fluid dynamic (CFD) software, the intake, exhaust and mixing processes are completely visualized ensuring that desired flow characteristics are employed by the geome
Price: 195.00