The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experiment...The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NOx emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder.展开更多
We report a hybrid nanogenerator that includes a triboelectric nanogenerator （TENG） and an electromagnetic generator （EMG） for scavenging mechanical energy. This nanogenerator operates in a hybrid mode using both ...We report a hybrid nanogenerator that includes a triboelectric nanogenerator （TENG） and an electromagnetic generator （EMG） for scavenging mechanical energy. This nanogenerator operates in a hybrid mode using both the triboelectric and electromagnetic induction effects. Under a vibration frequency of 14 Hz, the fabricated TENG can deliver an open-circuit voltage of about 84 V, a short-circuit current of 43 μA, and a maximum power of 1.2 mW （the corresponding power per unit mass and volume are 1.82 mW/g and 3.4 W/m^3, respectively） under a loading resistance of 2 MΩ, whereas the fabricated EMG can produce an opencircuit voltage of about 9.9 V, a short-circuit current of 7 mA, and a maximum power of 17.4 mW （the corresponding power per unit mass and volume are 0.53 mW/g and 3.7 W/m^3, respectively） under a loading resistance of 2 kΩ. Impedance matching between the TENG and EMG can be achieved using a transformer to decrease the impedance of the TENG. Moreover, the energy produced by the hybrid nanogenerator can be stored in a home-made Li-ion battery. This research represents important progress toward practical applications of vibration energy generation for realizing self-charging power cells.展开更多
基金Supported by the Engineering and Physical Sciences Research Council of the UK(No58338/01)
文摘The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NOx emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder.
基金This work was supported by Beijing Natural Science Foundation （No. 2154059）, National Natural Science Foundation of China （Nos. 51472055 and 61404034）, and the ＂Thousands Talents＂ program for pioneer researcher and his innovation team, China.
文摘We report a hybrid nanogenerator that includes a triboelectric nanogenerator （TENG） and an electromagnetic generator （EMG） for scavenging mechanical energy. This nanogenerator operates in a hybrid mode using both the triboelectric and electromagnetic induction effects. Under a vibration frequency of 14 Hz, the fabricated TENG can deliver an open-circuit voltage of about 84 V, a short-circuit current of 43 μA, and a maximum power of 1.2 mW （the corresponding power per unit mass and volume are 1.82 mW/g and 3.4 W/m^3, respectively） under a loading resistance of 2 MΩ, whereas the fabricated EMG can produce an opencircuit voltage of about 9.9 V, a short-circuit current of 7 mA, and a maximum power of 17.4 mW （the corresponding power per unit mass and volume are 0.53 mW/g and 3.7 W/m^3, respectively） under a loading resistance of 2 kΩ. Impedance matching between the TENG and EMG can be achieved using a transformer to decrease the impedance of the TENG. Moreover, the energy produced by the hybrid nanogenerator can be stored in a home-made Li-ion battery. This research represents important progress toward practical applications of vibration energy generation for realizing self-charging power cells.
