Waste heat recovery from exhaust gas is one of the most convenient methods to save energy in internal combustion engine-driven vehicles. This paper aims to investigate a reduction in waste heat from the exhaust gas of an internal combustion engine of a serial Diesel–electric hybrid bus by recovering part of the heat and converting it into useful power with the help of a split-flow supercritical CO₂ (sCO₂) recompression Brayton cycle. It can recover 17.01 kW of the total 33.47 kW of waste heat contained in exhaust gas from a 151 kW internal combustion engine. The thermal efficiency of the cycle is 38.51%, and the net power of the cycle is 6.55 kW. The variation in the sCO₂ temperature at the shutdown of the internal combustion engine is analyzed, and a slow drop followed by a sudden and then a slow drop is observed. After 80 s from stopping the engine, the temperature drops by (23–33)% depending on the tube thickness of the recovery heat exchanger. The performances (net power, thermal efficiency, and waste heat recovery efficiency) of the split-flow sCO₂ recompression Brayton cycle are clearly superior to those of the steam Rankine cycle and the organic Rankine cycle (ORC) with cyclopentane as a working fluid.

The article addresses the problem of estimating the specific electric energy consumption of urban electric transport under real operating conditions. It is substantiated that standardized driving cycles and rated energy consumption values do not always accurately reflect the actual operating modes of vehicles on urban routes, since energy consumption is affected by speed conditions, road conditions, passenger load, ambient temperature, auxiliary systems operation, and the number of stops, accelerations, and braking events. A simplified engineering model is proposed for adjusting the baseline specific electric energy consumption by means of a system of correction factors, which makes it possible to adapt the calculation to specific operating conditions under limited availability of telematics data. A distinctive feature of the proposed approach is the possibility of using a baseline energy consumption value determined from a driving cycle or vehicle specification data, followed by its adjustment according to the characteristics of an actual route. The proposed methodology was experimentally verified using certified trolleybus test data representing a vehicle with characteristics similar to a 12 m urban battery electric bus; however, further validation using dedicated battery electric bus datasets is required. For the reference vehicle operating on route No. 15 in Lutsk, with a route length of 10.2 km, the calculated electric energy consumption was 17.853 kWh at full mass and 12.498 kWh at curb mass, corresponding to approximately 1.75 and 1.23 kWh/km, respectively. The results were compared with experimental data and recent literature sources. The proposed methodology is intended for preliminary engineering assessment of electric energy consumption when detailed operational data are unavailable.