Analysis of temperature and altitude effects on the Global Energy Balance during WLTC

Abstract

In this work, the Global Energy Balance (GEB) of a 1.6 L compression ignition engine is analyzed during WLTC using a combination of experimental measurements and simulations, by means of a Virtual Engine. The energy split considers all the relevant energy terms at two starting temperatures (20°C and 7°C) and two altitudes (0 and 1000 m). It is shown that reducing ambient temperature from 20°C to −7°C decreases brake efficiency by 1% and increases fuel consumption by 4%, mainly because of the higher friction due to the higher oil viscosity, while the effect of increasing altitude 1000 m decreases brake efficiency by 0.8% and increases fuel consumption by 2.5% in the WLTC mainly due to the change in pumping. In addition, GEB shows that ambient temperature is affecting exhaust enthalpy by 4.5%, heat rejection to coolant by 2%, and heat accumulated in the block by 2.5%, while altitude does not show any remarkable variations other than pumping and break power.

A Logic Threshold Control Strategy to Improve the Regenerative Braking Energy Recovery of Electric Vehicles

“…Moreover, the front axle braking under the NEDC driving cycle is significantly smaller than the other five driving cycles. As described in Figure 3b, the duration of the WLTC test is 1800 s, and the test is divided into four zones: low-speed zone, medium-speed zone, high-speed zone, and super high-speed zone [59]. The corresponding durations are 589 s, 433 s, 455 s, and 323 s, respectively.…”

Development of Integrated Models for Thermal Management in Hybrid Vehicles

“…These are parameters for the combustion analysis tool (CALMEC) in which the main experimental input is the in-cylinder pressure signal. The first law of thermodynamics is applied between IVC (intake valve closing) and EVO (exhaust valve opening) to calculate the rate of heat release as the main result [136][20]. Among the results, the heat rejected to the coolant and oil is also calculated, which served to calibrate the heat rejected to the hydraulic circuits.…”