Toward co-optimization of renewable fuel blend production and combustion in ultra-high efficiency SI engines
Patrick Burkardt, Tamara Ottenwälder, Andrea König, Jörn Viell, Alexander Mitsos, Christian Wouters, Wolfgang Marquardt, Stefan Pischinger, Manuel Dahmen
Abstract
The shift from fossil to renewable fuels presents an opportunity to tailor a fuel’s molecular structure and composition to the needs of advanced internal combustion engine concepts, while simultaneously aiming for economic and sustainable fuel production. We have recently proposed a method for computer-aided design of tailor-made fuels that integrates aspects of both product and production pathway design. The present paper sets out to sequentially combine that method with experimental investigation on a single cylinder research engine and model-based early-stage process evaluation to create, validate, and benchmark a rationally designed multi-component biofuel for highly boosted spark-ignition engines. To this end, the computer-aided design approach is applied to a network of possible fuel components and their production pathways. The resulting optimal four-component fuel EBCC (50 mol% ethanol, 21 mol% 2-butanone, 15 mol% cyclopentane, and 14 mol% cyclopentanone) is analyzed with regard to combustion performance and estimated fuel production cost. Variations of both the indicated mean effective pressure and the relative air/fuel ratio were performed on an engine equipped with a compression ratio of 14.7. EBCC achieves indicated efficiencies that are significantly higher than those of RON 102 gasoline fuel and comparable to those of pure 2-butanone, an extremely knock-resistant fuel identified in a previous round of model-based fuel design. Furthermore, a strong reduction in engine-out soot emissions is observed compared to RON 102 gasoline. Early-stage process evaluation shows EBCC to have lower estimated fuel production costs than 2-butanone. Production costs of pure ethanol, however, are estimated to be even lower, mainly due to lower plant investment costs and a synthesis pathway that does not require hydrogen. The paper concludes with a brief perspective on further integration of the proposed sequential approach with the goal of co-optimizing the production and combustion of renewable fuel blends.