Time filter

Source Type

Xu M.,Beijing Jiaotong University | Xu M.,Beijing Key Laboratory of Flow | Zhang Z.,Beijing Jiaotong University | Zhang Z.,Beijing Key Laboratory of Flow | And 5 more authors.
Energy | Year: 2015

A lithium ion battery consists of numerous electrochemical cell units. Thermal and electrical behaviors of these local cell units have great influence on the battery's performance and safety. To study the relationship between the cell units and the battery cell, a pseudo 3D (three-dimensional) model was developed for a prismatic LiFePO4 battery by coupling the mass, charge, and energy conservations, as well as the cell electrochemical kinetics. The model treated the battery with current collecting tabs as 3D and the local cell units as 1D. Both electrochemical and thermal characteristics of the battery were studied by using this simplified model during the discharge process. A uniformity index characterizing the SOC (state of charge) distributions among 1D cell units was also introduced. This index was used to investigate the effects of the tab placement on the uniformity of the battery cell. The placement of the positive and negative current collecting tabs on the prismatic battery was found to have a significant effect on the distributions of its potential and local reaction rates, which therefore affect the heat generation rate, and thus the temperature distribution within the battery. © 2014 Elsevier Ltd.


Niu S.,Beijing Jiaotong University | Niu S.,Beijing Key Laboratory of Flow | Chen M.,Beijing Jiaotong University | Chen M.,Beijing Key Laboratory of Flow | And 3 more authors.
Fuel | Year: 2016

The combustion behavior of sewage sludge under oxy-fuel condition was evaluated based on a thermal analysis technique. At heating rates of 20-80 K min-1, the ignition temperatures of the sewage sludge were between 250 and 300 °C under air and three O2/CO2 atmospheres (oxygen contents of 21%, 30% and 40%). The burning process of the sewage sludge in air was very similar to 30%O2/70%CO2 atmosphere. The ignition and burnout temperatures of the sewage sludge decreased with increasing oxygen contents in O2/CO2 atmospheres. The average comprehensive performance indices of the sewage sludge in 40%O2/60%CO2 atmosphere were about 2 times more than that in 21%O2/79%CO2 atmosphere. Moreover, the ignition and comprehensive performance indices of the sample sharply rose up with increasing heating rates. The ignition and comprehensive performance indices of the sewage sludge in 30%O2/70%CO2 atmosphere at 80 K min-1 were about 4 times and 6 times more than that at 20 K min-1. The kinetic parameters in four combustion stages around two peaks were evaluated based on the Coats-Redfern method coupled with Ozawa-Flynn-Wall equation. There were certain kinetic compensation effects for both main combustion stages and different oxygen contents in oxy-fuel. © 2016 Elsevier Ltd. All rights reserved.


Liu X.,Beijing Jiaotong University | Liu X.,Beijing Key Laboratory of Flow | Chen M.,Beijing Jiaotong University | Chen M.,Beijing Key Laboratory of Flow | And 2 more authors.
Renewable Energy | Year: 2016

The oxygen enriched air combustion performance and ash fusion characteristics of two typical agricultural and wood samples (corncob and hardwood) and bituminous coal were assessed using a thermal analysis technique. The effects of oxygen contents, sample kinds and blending ratios on the combustion performance were revealed, and the effects of sample properties and blending ratios on the ash fusion of samples were also evaluated. Biomasses showed better ignition performance and comprehensive combustion performance than bituminous coal. The ignition and comprehensive performance indices of corncob/coal blends were higher than those of hardwood/coal blends. Apparently, the combustion performances of biomass/coal blends improved with increasing the oxygen contents and blending ratios of biomass. Certain synergistic interactions were detected between Chinese bituminous coal and corncob or hardwood during the co-combustion at 100% and 80% oxygen contents. The ash fusion reactions of corncob, hardwood and bituminous coal mainly occurred in the ranges of 1036-1079 °C, 1046-1289 °C, and 1260-1290 °C, respectively, while the ash fusion reaction of corncob/coal blends occurred in the range of 1096-1289 °C. © 2016 Elsevier Ltd.

Loading Beijing Key Laboratory of Flow collaborators
Loading Beijing Key Laboratory of Flow collaborators