2019 Volume 61 Issue 197 Pages 213-223
Loss Reduction Team in the SIP’s “Innovative Combustion Technologies” has been focusing on utilizing the exhaust gas energy and reducing mechanical losses in theory and practice in order to contribute to achieving a 50% brake thermal efficiency targeted in both 2.0 L automotive gasoline and diesel engines. Major components of the turbocharging system were optimally redesigned based on 3D CFD modeling validated by measurements. A thermoelectric system was developed to utilize the energy of the exhaust gas downstream of the turbocharger outlet. A device BiTe was chosen for an exhaust gas temperature range of 200℃ to 300℃. The number and layout of the modules were optimized by using a heat transfer model taking into account the entire engine cycle thermal efficiency. Major moving components were also improved to simultaneously lower their friction forces and avoid wear and seizure using special surface treatments and low viscosity oils with additives, resulting in achieving up to a 55% friction reduction compared with the baseline. Detailed numerical models and measurement methods have been developed to explain and predict these improvements. Eventually, the team could increase the bake thermal efficiency by 3.5%pt and 3.0%pt in the gasoline and diesel engines, respectively.
