## 1 Introduction
reflected on the need to develop integrated and more advanced thermal management control strategies to reduce light-off time without significant energy penalty [18]. On the other hand, the catalyst control technologies are simpler and do not require modifying the engine's set up since they are focused on reducing the light-off temperature of the catalytic conversion by means of trying to develop alternative catalytic materials and/or reducing the time to reach the light-off temperature. This second and more realistic strategy is currently investigating several alternatives such as increasing the heat transfer inside the catalyst using higher cell densities and thinner wall designs, insulating the exhaust manifold, and moving the SCR as close as possible to the engine's block or adding an electrical resistance to preheat the SCR. All in all, the simplicity of electrically preheated catalysts (EHCs) makes it the most cost-effective technology for solving the problem [9; 18]. In this direction, several prototypes of a catalytic converter with an exhaust heater for preheating the catalyst specifically designed for CNG engines have been tested with very promising results [18; 19]. These heat-integrated catalysts require a constant heating of 2.5 kW during 120 s in a 1.8 L CNG engine for a 90% reduction of CH4 emissions in a New European Driving Cycle (NEDC) test in comparison with non-preheated TWC values. NEDC consists of repeated urban and extra-urban driving cycles usually performed on a roller test bench with a total duration of 1180 s. This 2.5 kW in 120 s is equivalent to a mean electrical power consumption of 254 W during the NEDC that must be generated by the alternator and, hence, by the engine. This is the reason why this technical solution contributes to increasing the fuel consumption of the vehicle. [PERSON] et al. [20] analyzed the use of an automotive thermoelectric generator (ATEG) coupled to an exhaust gas heater (EGH). This system could reduce up to 97% the NOx emitted by a light duty vehicle during cold starts. The ATEG is used to convert waste heat from exhaust gases, downstream of the aftertreatment system, into electricity. A battery is used to store the electricity generated, which can be used by the EGH later to shorten the time that urea is injected and reduce NOx emissions. This EGH + ATEG system, also known as thermoelectric aftertreatment heater (TATH), was designed to be energetically autonomous, so there is no extra consumption of fuel. Note that the ATEGgenerates less power than the EGH. However, the EGH only works for a few minutes while the ATEG all the driving cycle. Therefore, the energy consumed and produced can be balanced. This study is based on the developments presented in [20; 21] but from a perspective of compliance with current EURO VI and future EURO VII regulations. The objective of this work is to experimentally quantify the energy required by an EGH to fulfil the EURO VI and EURO VII regulations. The EGH will be retrofitted upstream of the standard after-treatment system of a EURO VI certified HDV. The idea is to obtain the power and energy needed to make SCR work at its maximum efficiency. Then, the effect of the added weight, the additional back pressure caused in the exhaust pipe and the extra electricity consumption will be analyzed. This will lay the groundwork for the future development of a thermoelectric recovery system capable to produce the energy required by the EGH in a real mission of a long-haul Euro VI HDV. The end goal is reducing the pollutant emissions without the need to increase the fuel consumption.