Design and simulation of an exhaust based thermoelectric generator (TEG) for waste heat recovery in passenger vehicles

The increasing demand for electric power in passenger vehicles has motivated several research focuses since the last two decades. This demand has been revoluted by the unrelenting, rapidly growing reliance on electronics in modern vehicles. Generally, internal combustion engines lose more than 35% of the fuel energy in exhaust gas. Comparing this huge loss to every day's growing oil price, one could understand how the recovery of such losses could help the economy, as well as providing the additional power sources required by contemporary vehicle systems. There are three fundamental advantages of thermoelectric generators (TEGs) over other power sources are three; they do not have any moving parts as they generate power using Seebeck solid-state phenomena, they have a long operation lifetime, and they can be easily integrated to any vehicle's exhaust system. This thesis presents a novel TEG concept aims to resolve the thermal and mechanical disputes faced by the research community. A novel procedure for designing exhaust based TEG is presented as well. Several simulation models are used to analyze the TEG performance. The significance of the novel TEG is discussed through a detailed comparison with experimental results from Clarkson University and Nissan Motors TEG prototype tests. The simulation results showed a huge increase in the energy density achieved by the novel TEG to reach 11.92 W/kg

Analyzing the effect of free stream turbulence on gaseous non-premixed flames

The effects of free stream turbulence on non-premixed flames are numerically analyzed. The Spalding eddy dissipation mathematical model is used to control the reaction rate by the large-eddy time scale. The turbulence energy production and dissipation rates are simulated by the ?-e turbulence model in order to investigate the dependence of the combustion properties on free stream turbulence. The reacting NS equations were spatially discretized and solved through a finite volume scheme and a decoupled pressure-velocity approach, respectively. The flame was assumed to be steady-state, two dimensional and axisymmetric. The reported results include the velocity, temperature and turbulent reaction rate along the flame propagation field. It is found that the increase of free stream turbulence intensity reduces the reaction zone significantly, hence, induces the flame extinction process