On the emission reduction through the application of an electrically heated catalyst to a diesel vehicle

Exhaust emissions from diesel engine powered vehicles are considerably high during cold start and warm‐up, because of the poor catalyst performance due to the insufficient catalyst temperature. The controlled heat injection allowed by electrically heated catalysts can effectively reduce the catalyst light‐off time with relatively moderate fuel penalty. This paper compares the exhaust temperature and emissions of a case study diesel vehicle in cold and warm start conditions, and proposes two electrically heated catalyst control strategies, which are evaluated in terms of emission reduction and energy consumption with different target temperature settings. In addition, a new performance indicator, that is, the specific emission reduction, is used to evaluate the after‐treatment system and associated thermal management. For the worldwide harmonized light vehicle test cycle, the results without electrically heated catalyst show that from both cold and warm start conditions a large amount of operating points of the engine is located in the region of partial catalyst light off. Moreover, emissions, especially in terms of carbon monoxide and hydrocarbon, significantly decrease with the electrically heated catalyst implementation, for example, by at least 50% from cold start; however, they still tend to be rather substantial when the fuel is re‐injected after the engine cutoff phases. The exhaust temperature is lower than the target values in the sections of the driving cycle in which the electrically heated catalyst power is saturated according to the maximum level allowed by the device. The carbon dioxide penalty brought by the electrically heated catalyst ranges from 3.93% to 6.65% and from 6.49% to 9.35% for warm and cold start conditions, respectively

Numerical Solutions of 2-D Steady Incompressible Driven Cavity Flow at High Reynolds Numbers

Numerical calculations of the 2-D steady incompressible driven cavity flow are presented. The Navier-Stokes equations in streamfunction and vorticity formulation are solved numerically using a fine uniform grid mesh of 601x601. The steady driven cavity solutions are computed for Re<=21,000 with a maximum absolute residuals of the governing equations that were less than 10-10. A new quaternary vortex at the bottom left corner and a new tertiary vortex at the top left corner of the cavity are observed in the flow field as the Reynolds number increases. Detailed results are presented and comparisons are made with benchmark solutions found in the literature

ENVIRONMENTAL ASSESSMENT OF WIND ENERGY CONVERSION SYSTEMS IN TURKEY

Nowadays, approximation of fossil-based fuel to exhaustion reveals that countries will have difficulty in meeting energy needs in the near future. Renewable energy sources are prognosed as a solution to this problem. Among the renewable energy sources, wind energy, since having many advantages, has a key role in meeting the energy demand. Wind energy recycling systems have very little negative effects to the environment. Therefore, as an alternative to conventional energy cycling systems, wind energy has intensive attention. In this study, effects of wind turbines to the environment such as carbon dioxide emission, noise effect, electromagnetic effect, field usage effect and other effects will be examined in details.WOS:0003028435000392-s2.0-8486013336