The importance of new technologies to improve the performance and fuel economy of internal combustion engines is now widely recognized and is essential to achieve CO 2 emissions targets and energy security. Increased hybridisation, combustion improvements, friction reduction and ancillary developments are all playing an important part in achieving these goals. Turbocharging technology is established in the diesel engine field and will become more prominent as gasoline engine downsizing is more widely introduced to achieve significant fuel economy improvements.The work presented here introduces, for the first time, a new technology that applies conventional turbomachinery hardware to depressurize the exhaust system of almost any internal combustion engine by novel routing of the exhaust gases. The exhaust stroke of the piston is exposed to this low pressure leading to reduced or even reversed pumping losses, offering >5% increased engine torque and up to 5% reduced fuel consumption. This method has the distinct advantage of providing performance and fuel economy improvements without significant changes to the structure of the engine, the combustion system or lubrication system. The Turbo-Discharging concept is introduced and analyzed. A combination of filling/emptying models and 1-D gas dynamic simulations were used to quantify the energy flows and identify optimum valve timings and turbomachine characteristics. 1-D gas dynamic simulation was then used to predict primary fuel economy benefits from TurboDischarging. Secondary benefits, such as extended knock limits are then discussed.
DOI: 10.1243/09544070JAUTO508Abstract: New mathematical models are proposed that predict fluid flow pressure gradients in gelcast ceramic foam diesel exhaust particulate filters by considering the foam structure conceptually as serially connected orifices. The resulting multiple orifice mathematical (MOM) model is based on the sum of a viscous term derived from an extended Ergun model and the kinetic energy loss derived from the Bernoulli and conservation of mass equations. The MOM model was calibrated using experimental data obtained from measuring the air flowrate and pressure drop across a physical large-scale three-dimensional model of a cellular foam structure produced using rapid manufacturing techniques. The calibrated model was then validated using fluid flow data obtained from gelcast ceramic foam filters of various cell sizes and was found to require no empirical recalibration for each gelcast ceramic foam sample. The MOM model for clean filters was extended to predict pressure gradients of filters loaded with particulate matter (PM). The prediction of pressure gradients through gelcast ceramic filters using the MOM model for clean and PM-loaded cases was shown to be in reasonable agreement with experimental data. The models were finally applied to design a filter for a turbocharged, charge-cooled, 2.0 l, fourstroke, common rail, direct injection passenger car diesel engine.
Increasing applications for gelcast ceramic foams is making the effective, accurate and cost effective measurement of pore diameter and distribution of significant value to a wide range of research fields. Current methods either do not directly measure pore diameter or they require high equipment and time costs. Measuring pore diameter directly from sample cross sections is both rapid and cost effective but, due to the random nature of the pore location during sectioning of the sample, it under predicts the pore diameter. The proposed method identified that the mean measured pore diameter was 79% (2 s.f.) of the actual pore diameter. Numerical methods for correcting the pore distribution as well as the average pore diameter are presented.
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