In this study, an in-cylinder steam injection method is introduced and applied to a turbocharged diesel engine for waste heat recovery and NO_x emission reduction. In the method, cool water was first heated into superheated steam by exhaust. Then the superheated steam was directly injected into the cylinder during the compression stroke. The potential for fuel savings and NO_x emission reduction obtained by this method was investigated. First, a two-zone combustion model for the baseline engine was established and calibrated with the experimental data. Based on the model, the effects of steam injection mass, temperature, and timing on engine performance and NO_x emission were investigated. The results demonstrate that in-cylinder steam injection can improve engine performance and reduce NO_x emissions significantly at all engine speeds. Optimal steam injection mass is obtained under full load at engine speed from 1000 rpm to 1900 rpm when the steam injection timing and temperature are −30° and 550 K, respectively. Under those conditions, engine torque is increased by 9.5–10.9%, brake-specific fuel consumption (BSFC) is reduced by 8.6–9.9%, and NO_x emission is decreased by 83.4–91.8%. Steam injection mass and injection timing are the main parameters that significantly affect engine performance and NO_x emission.

Overcharge is one of the main factors that lead to thermal runaway of lithium batteries. However, there is no research on the quantitative relationship between overcharged state and gas production, so as to effectively monitor the safe state of the battery and avoid thermal runaway. In this paper, X-ray computed tomography (CT) is proposed to explore the overcharge battery. The internal structure changes of bulge deformation and electrode separation is observed from tomographic images of two different cross-sectional directions. The relationship between gas production and overcharge state of charge (SOC) is quantitatively analyzed. As overcharge SOC increases, gas production increases exponentially. Gas distribution is analyzed by density distribution feature (DDF) vector. The gas production is mainly distributed in the middle of the overcharge batteries. It is envisaged that these techniques can be used to better understand the overcharge of battery nondestructively, visually and effectively, then will lead to avoid the occurrence of thermal runaway.

Overdischarge is one of the main factors of lithium-ion battery failure, due to the inconsistency of lithium-ion battery in pack. However, the failure mechanism remains unclear. This article introduces the X-ray computed tomography (CT) to explore the gas production and copper dissolution of lithium battery during overdischarge state. From tomographic images in two different cross-sectional directions, the internal structure changes of bulge deformation and copper deposition are observed to quantitatively analyze the relationship between copper deposition and overdischarge state of charge. The position distribution is analyzed by density distribution feature, which indicate that the gas production is mainly distributed in the middle of the battery, and the copper deposition is distributed around the outer side. The experimental result shows that X-ray CT is a nondestructive, quantitative, visual, and effective way to study the internal structure and material distribution of the overdischarge battery, so as to effectively monitor the state of the lithium-ion battery, to avoid dangerous problems such as internal short circuits and thermal runaway.

For retired power batteries, it is difficult for single cell to meet the power requirements, and there is a problem of poor consistency between multiples. Therefore, re-grouping and consistency assessment are required for cascade utilizaton of retired batteries. In this paper, the remaining capacity test and HPPC test of retired lithium power batteries were carried out. And then the consistency of characteristic parameters of retired batteries under different SOC conditions was compared and analyzed based on capacity, internal resistance and other parameters. The results show that as the battery discharges, the ohmic internal resistance increases, and the consistency of polarization resistance and polarization capacitance are obviously deteriorated. Therefore, it is more reasonable to group them into consistent groups according to the electrochemical parameters of retired batteries at high discharge depth. Moreover, there is no strong correlation among the characteristic parameters such as open-circuit voltage, internal resistance and capacitance. Multiple parameters are required to evaluate the consistency of retired lithium batteries.