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In the present research, the energy flow of electric vehicle batteries under different environmental temperatures was experimentally examined in a climate chamber. The energy flow characteristics, energy loss conditions, and the critical components' operating conditions and working efficiency under different environmental temperatures were comparatively analyzed. The test results show that the environmental temperature has a profound impact on an electric vehicle's performance and the critical components' working conditions. The driving mileage of the tested vehicle at −7 °C, 23 °C, and 35 °C was found to be 162.89 km, 256.09 km, and 198.69 km, respectively. The environmental temperature does not have much effect on the loss of the motor and motor control unit under driving conditions, and the proportion of those at different temperatures is in all cases about 18%. The battery-recycled energy at 23 °C under braking conditions is much higher than that at −7 °C and 35 °C, leading to a longer driving range. The power battery pack thermal transfer loss at −7 °C is much greater than that at 23 °C and 35 °C due to the low charging and discharging efficiency and the high energy consumption required to warm up the battery at a low environmental temperature. The compressor energy consumption accounts for a large proportion in both braking and driving conditions at 35 °C, and the proportions are 15.25% and 12.41%, respectively. The battery state-of-charge drops the fastest at −7 °C, followed by 35 °C, due to the differences in the power demands of air conditioning, warm air positive temperature coefficient (PTC), and battery PTC in high- and low-temperature environments. The working condition of the front motor under driving conditions at 35 °C is the most severe and leads to the lowest working efficiency. [ABSTRACT FROM AUTHOR]

In this paper, the vehicle energy flow test of a heavy hybrid commercial vehicle is carried out on the chassis dynamometer with an ambient chamber under the C-WTVC test cycle. Energy flow characteristics, driving modes, the power system and key component working status and efficiency of the vehicle are studied. The test results show that the energy used to drive the vehicle accounts for 30.99% of the total energy. Heat transfer loss of the radiator and the motor cooling loop accounts for 8. 89% and 2.6% of the total energy respectively. The remainder loss accounts for 50.67% of the total energy which includes engine pump gas loss, friction loss, combustion loss and exhaust enthalpy increase. In the driving mode, pure electric drive, parallel drive, drive power generation and the energy recovery mode account for 9.1%, 29.56%, 18.51% and 23.61% of the total cycle time respectively. The recovery efficiency of braking energy is 81.95%. There are about 65% of the engine working points located below 200 g/ (kW ⋅ h) areas, and the thermal efficiency of the engine is 36.81% during the whole test cycle. About 24% of the motor working points are located in areas with a mechanical efficiency exceeding 94%. About 53% of the motor working points are located in areas with a mechanical efficiency below 92%, which mainly appear when the motor is driven by the engine to generate electricity or recover energy. This study provides guidance for improving the energy efficiency of hybrid commercial electric vehicles, and the following research can be focused on reduction of engine remainder loss and optimization of engines and motor working points. [ABSTRACT FROM AUTHOR]

The effects of an anodic oxidation coating on piston temperature distribution and thermal stress are investigated by establishing an inverse heat conduction problem in the form of an optimization problem in an aero-engine. A thermal analysis is carried out for both coated and uncoated pistons at 2100 rpm under 50 and 100% of full load. Specially manufactured metal plugs (templugs) were installed in both kinds of pistons to measure the temperature of every survey station. The effect of the secondary motion of the piston and piston ring on the lubrication oil film was taken into consideration in determining the heat transfer coefficient. There was reasonable agreement between the numerical method and experimental measurement, shown with an error analysis using a third-order polynomial fit technique. Research results showed that the maximum temperature of the anodic oxidation coated piston head increased to 298.5°C and 309.6°C under 50 and 100% of full load, respectively. In addition, there was a temperature reduction in the skirt for the coated piston in contrast to the temperature for the uncoated pistons under 50 and 100% of full load. The temperature distribution and thermal stress in the pin boss were then analyzed. The results indicated an increase of maximum temperature; however, the maximum thermal stress decreased for the anodic oxidation coated piston in the pin boss. Furthermore, a 200-h durability test was performed, proving the thermal load of the piston with anodic oxidation coating would not damage the piston. Also, the effect of the anodic oxidation coating technique on aero-engine emissions was investigated. The anodic oxidation coating for the aero-engine combustion chamber slightly improved CO and HC under 50 and 100% of full load. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Ignition timing has been optimized. [•] 1% H2O has been added. [•] Positive results have been achieved in engine torque, BSEC, CO emissions and HC emissions. [•] NOx and CO2 emissions go up. [ABSTRACT FROM AUTHOR]

For investigating the temperature distribution of cylinder head under the coaction of burned gas and coolant, the temperature field of the cylinder head of a diesel engine is analyzed with fluid-solid coupling technique. Firstly, a CFD analysis is carried out on in-cylinder working process and water jacket with software AVL-Fire, and the thermal boundary conditions for the wall surfaces of cylinder and water jacket are obtained. Then the thermal boundary conditions are mapped to FE meshes, and the temperature field of cylinder head is calculated by FE analysis. The results demonstrate that the highest temperature of cylinder head is far lower than the permissive temperature of material, and the temperature distribution rationally explains the "heat" working environment of cylinder head. [ABSTRACT FROM AUTHOR]