Developing Computational Fluid Dynamics (CFD) Models to Evaluate Available Energy in Exhaust Systems of Diesel Light-Duty Vehicles

Abstract

Around a third of the energy input in an automotive engine is wasted through the exhaust system. Since numerous technologies to harvest energy from exhaust gases are accessible, it is of great interest to find time-and cost-efficient methods to evaluate available thermal energy under different engine conditions. Computational fluid dynamics (CFD) is becoming a very valuable tool for numerical predictions of exhaust flows. In this work, a methodology to build a simple three-dimensional (3D) model of the exhaust system of automotive internal combustion engines (ICE) was developed. Experimental data of exhaust gas in the most used part of the engine map in passenger diesel vehicles were employed as input for calculations. Sensitivity analyses of different numeric schemes have been conducted in order to attain accurate results. The model built allows for obtaining details on temperature and pressure fields along the exhaust system, and for complementing the experimental results for a better understanding of the flow phenomena and heat transfer through the system for further energy recovery devices.

A zero-dimensional model to simulate injection rate from first generation common rail diesel injectors under thermodynamic diagnosis

“…Originally, the first test plan was used in order to experimentally characterize exhaust pipe heat transfer of the engine [26]. The main advantage of using these two test plans consists of the possibility to test the injectors with multiple injections with short energizing times, characteristic of both urban and extra-urban driving conditions (test plan i), and with long injector energizing time as employed typically of used in a test for spray modelling (test plan ii).…”

“…Values of injection pressure and injection timing shown in Table 4 were recorded from tests carried out in the test bench with the light-duty engine NISSAN YD22, equipped with 7H150 injector. Figure 3 shows these engine operating modes [26]. Table 4 Main characteristic parameters of injection for split injection with Denso 7H150 injector (9 engine modes).…”

“…As can be seen in Figure 3, the 9 operating modes are located in the lower-left zone of the engine map (Torque-engine speed), limited by the full load curve (maximum torque at each engine speed). These modes cover the most part of the zone characterized by the New European Driving Cycle (NEDC) [26].…”

Effects of the internal structures of monolith ceramic substrates on thermal and hydraulic properties: additive manufacturing, numerical modelling and experimental testing

“…The heat transfer coefficient was calculated from the average sample surface temperature and inlet and outlet temperatures obtained from the experiment [52]. Radiation heat transfer was not taken into the account since the outer tube temperatures were low [53]. Total heat losses Q were obtained with Eq.…”

Why the Development of Internal Combustion Engines Is Still Necessary to Fight against Global Climate Change from the Perspective of Transportation

“…A revolution is approaching with respect to traditional gasoline and diesel engines making the boundaries between them disappear as deeper knowledge and greater control of the combustion process is acquired [34]. Advanced injection systems [35,36], turbochargers [37,38], organic Rankine cycles (ORC) [39], hybridization [40,41], multifuel solutions [42][43][44], or advanced combustion concepts are becoming a part of the ICE context. All these strategies are dedicated to extract every Joule of energy from the fuel.…”