Optimization of the Charge Motion in Internal Combustion Engines Driven by Sewage Gas for Combined Heat and Power Units

Abstract

In this study, the influence of the charge motion on the internal combustion in a spark ignition sewage gas-driven engine (150 kW) for combined heat and power (CHP) units was investigated. For this purpose, the geometry of the combustion chamber in the immediate vicinity to the inlet valve seats was modified. The geometrical modification measures were conducted iteratively by integrative determination of the swirl motion on a flow bench, by laser-optical methods and consecutively by combustion analysis on a test engine. Two different versions of cylinder heads were characterized by dimensionless flow and swirl numbers prior to testing their on-engine performance. Combustion analysis was conducted with a cylinder pressure indication system for partial and full load, meeting the mandatory NOx limit of 500 mg m−3. Subsuming the flow bench results, the new valve seat design has a significant enhancing impact on the swirl motion but it also leads to disadvantages concerning the volumetric efficiency. A comparative consideration of the combustion rate delivers that the increased swirl motion results in a faster combustion, hence in a higher efficiency. In summary, the geometrical modifications close to the valve seat result in increased turbulence intensity. It was proven that this intensification raises the ratio of efficiency by 1.6%.

Review on Cylinder Head Design for Swirl Optimization

“…The cylinder pressure reduced by 19.9% in the modified flow condition compared to that of the standard and there is reduction in the heat release by 12.15% for the modified flow to that of the standard flow. [3] Lucas Konstantinoff et al (2017) have explained about cylinder heads with two different valve-seat designs were tested on a static flow bench to acquire comparable data describing flow characteristics. Data on the air flow rate and angular momentum generated by the inlet port was used to calculate the flow and swirl coefficients and describe the cylinder heads static-flow performances.…”

“…They have proven that a goal-orientated optimization of the charge motion has the potential to improve internal combustion and, hence, thermal efficiency. [4] Pankaj N.Shrirao et al (2015) studied about the configuration of cylinder head with three oval shape dimples enhances the turbulence and hence results in better air-fuel mixing process. As a result, the thermal efficiency is increased and BSFC and exhaust emissions are reduced.…”