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Extraction of shale gas from shale reservoirs is significantly affected by shale wettability. Recently, thermal recovery technologies (e.g., combustion) have been tested for shale gas recovery. This requires an understanding of the wettability change mechanism for thermally treated shale samples. In this study, the effect of combustion on shale wettability was investigated. Shale samples were first processed to obtain smooth surfaces and then combusted at temperatures of 200, 400, and 800 °C. The initial contact angles and dynamic behavior of water droplets on shale surfaces were recorded using the sessile drop method. It was found that pores and fractures were generated on the shale surfaces following high-temperature combustion. The pore volume and diameter increased with increasing combustion temperature, which improved the connectivity of hydrophilic pore networks. Compared to a raw shale sample, the shale sample combusted at 400 °C showed a smaller initial water contact angle and a more rapid decrease in the contact angle because of the oxidation of organic matter and generation of pore structures. Water droplets were found to completely spread over the surface of the shale sample combusted at 800 °C because of the generation of fractures. Moreover, the van der Waals potential between water droplets and combusted shale samples was determined to be stronger. However, the initial contact angle and dynamic behavior of water droplets did not show a significant change for the shale sample combusted at 200 °C. As a result, high-temperature combustion (≥400 °C) can be used to significantly improve the hydrophilicity of shale.

This study aims to reveal the evolutionary process of particles during the diesel exhaust transport process and to further understand the effects of diesel exhaust transport distance (DET) on a particulate microstructure. Specifically, the micromorphological, particle size distribution, and aggregate characteristics of particles as well as the variation of the structural characteristics of elementary carbon particles (ECPs) as DET changed were examined using an engine exhaust particle size spectrometer, a high-resolution transmission electron microscopy system, and a small-angle X-ray scattering system. The results show the following: As DET increased, the chains gradually lengthened, the extent of accumulation and stacking increased, and a number of clusters gradually rose. The average particle diameter increased from 23.1 nm at 0 m to 92.7 nm at 3 m. In addition, as DET increased, the number of accumulation-mode particles, the number of folded, curved carbon layers in the inner core of carbon particles, and the disorderliness of carbon layers in the outer shell of carbon particles all increased. Moreover, the boundary between the inner core and the outer shell became increasingly obscure. As DET increased, there was a gradual decrease in the difference in electron density between particles, and the fractal dimensionality of the distribution, average cross-sectional size, radius of gyration, and axial length of pores were, respectively, 33.3%, 40%, 38.2%, and 50.3% less at 3 m than at 0 m. Besides that, the number of small ( 10 nm) pores gradually decreased. Overall, as DET increased, pore size and number decreased. There was a gradual increase in the number of folded and curved carbon layers in the inner core of ECPs and an increase in the disorderliness of carbon layers in their outer shell as DET increased. Furthermore, the boundary between the inner core and the outer shell became increasingly obscure as DET increased. The crystallite size of ECPs decreased from 1.365 nm at 0 m to 1.098 nm at 3 m. This suggests that the number of continuously arranged carbon atoms decreased, the arrangement of carbon atoms was more disorderly, and the degree of graphitization decreased. As DET increased, there was a gradual increase in the interlayer spacing and curvature of ECPs. This suggests that increasing DET led to a more disorderly distribution of electron orbitals inside the carbon layers, less electron resonance stability in the carbon layers, greater oxidative activity of ECPs, and greater inherent oxidative capacity of particles.

Recently, thermal recovery technologies such as combustion have been studied for shale gas recovery. Thus, understanding of the microstructure of combusted shale is essential for evaluating the effects of thermal treatment on shale gas transport capacity. In this study, the effect of combustion on shale microstructure changes was investigated. Firstly, different-sized shale samples were combusted at 450 °C for 30 min. Afterward, shale microstructure properties including surface topographies, porosity and permeability of the raw and combusted shale samples were measured and compared. It was found that the pore volume and specific surface area increased after combustion, especially for small pulverized samples. According to surface topography obtained from atomic force microscope, more rough surfaces were obtained for the combusted shale due to larger pores and generation of thermal fractures caused by the removal of organic matter. Based on the mercury intrusion porosimetry measurements, the porosity of the shale samples increased from 2.79% to 5.32% after combustion. In addition, the permeability was greatly improved from 0.0019 to 0.6759 mD, with the effective tortuosity decreased from 1075.40 to 49.27. As a result, combustion treatment can significantly improve the gas transport capacity.

Extracting coalbed methane is challenging due to the strong gas adsorption capacity and low matrix permeability of the coalbed. Recently, thermal recovery methods have been tested to promote methane recovery. In this study, anthracite samples were heated to different temperatures to investigate the internal pressure variation and microstructure changes. It was found that higher temperature resulted in higher internal pressure. At low temperatures, the increase in the internal pressure was mainly due to gas desorption. At 500°C, thermal cracking gases provided the main contribution to the high internal pressures, as more gaseous products were generated at the higher temperature. In addition, the microstructure of coal significantly changed after combustion, including the increased pore volume, the increased specific surface area, and the generation of microfractures. These changes could potentially increase the porosity and permeability of coal. Thus, high‐temperature thermal treatments not only provided energy for gas desorption and organic matter decomposition but also improved conditions for gas transport.

The nano-fuel are prepared by dispersing CNT, CeO2, and Co3O4 nanoparticles in n-tetradecane (C14). This experimental study investigates the effect of nanoparticles mass fraction as well as the var...

Silicon is one of the most promising anode candidates for the next generation Li-ion batteries. Polymer binders play a crucial role as they are very essential to keep mechanical integrity of the electrodes and affect the solid electrolyte interphase (SEI) properties. Alginate appears to be the best binder system for Si electrode and it is able to form three-dimensional (3D) conductive polymeric network through in-situ inter-chain cross-linking by divalent cations. Herein, the effects of different cross-linking cations (Cu2+, Ca2+, Fe2+ and Ni2+) on the electrochemical behavior of silicon nano-sized particle anodes with alginate binder are investigated. It is found that all the alginate networks bridged by the transition metal cations are able to tolerate the volume change of silicon and effectively restrict the volume expansion of the Si particles. The overall electrochemical properties of the Si anode with Ni cations cross-linked alginate exhibit the highest reversible capacity, extraordinary cycleability and superior rate capability. The main reason for the electrochemical enhancement is explained by the improved stability of SEI film on the Si surface.

This study carries a comprehensive investigation on the influences of the key environmental and operating parameters on SOC and cycling life of the Ni-MH battery. The Ni-MH cells were tested through loading the actual road spectrum at different temperatures (25/35/45°C). Other parameters of SOC fluctuation and currents are set to be 10% and 15.5A by average, respectively. Tests have been performed to obtain the OCV (open circuit voltage)~SOC curves at different temperatures under the 1-C rate of charging/discharging. The investigation results show that the capacity decay compared to initial capacity is increased by a slight 2.46% at 45°C, demonstrating an excellent cycling performance of the Ni-MH battery. Additionally, the battery polarization effect is found to be correlated to the charging and discharging processes and temperature. In summary, this study presents a comprehensive factor analysis needed to achieve a reliable SOC estimate for the Ni-MH based HEV.

High power cylindrical Ni-MH battery cells have a heavy heat load because of their high discharge rate and large equivalent internal resistance. This heavy heat load, together with an imbalanced flow in parallel liquid cooling systems, can lead to variances in the temperature of each cell in the entire battery pack, thereby reducing the life cycle of the battery pack. In this paper, a parallel-series combined liquid cooling system for a 288V Ni-MH battery pack was designed, and several parameters that influence the flow balance of the system by heat transfer and fluid dynamics were calculated. Then, a thermal-fluid simulation was executed with different parameters using StarCCM+ software, and the simulation results were validated by a battery pack temperature experiment on a bench and in a vehicle. The results indicate that the cell&rsquo, s temperature and temperature differences can be kept within an ideal range. We also determined that within the battery power requirements and structural spacing limits, the total flow rate of the cooling liquid, the cross-sectional area ratio of the main pipe to the branch pipes, and the number of internal supporting walls in each branch pipe need to be large enough to minimize the cell&rsquo, s maximum temperature and temperature differences.

One of the most important challenges in engine applications is to reduce emissions. Improving fuel quality by adding nanoparticles is an appropriate method to meet this challenge. In the study, two typical nanometre materials, i.e., CNT (which is non-metallic and possesses excellent thermal conductivity) and nano-MoO3 (which represents the metal oxides and owns favourable catalytic function), were examined comparatively as additives in neat diesel. CNT-diesel and MoO3-diesel nano-fuels were prepared using the appropriate physical and chemical dispersion methods. Experiments were performed in a single-cylinder common rail diesel engine to investigate and compare the combustion and emissions performances of nano-fuels with neat diesel. It was found that both CNT-diesel and MoO3-diesel achieved better performance in fuel economy, combustion and emissions than neat diesel. These outcomes may be due to the excellent thermal conductivity and surface deficits of CNT and the good catalytic oxidation function of MoO3. In addition, CNT-diesel was found more promising, because it seems to produce more benefits in promoting combustion efficiency and emissions reduction than MoO3-diesel.

External morphology and internal carbonaceous compositions are important characteristics for the source recognition of atmospheric particulate matter (PM). The fractal dimension of morphology and carbon components of diesel PM with different sizes both at high and low load were studied through fractal theory and thermal optical reflection method. It is revealed that small-size PM absorbs more soluble organic fractions and correspondingly has greater box dimension. Due to heavy aggregation, PM collected at low load has greater box dimension than that at high load because of heavy aggregation. OC1, which is the most volatile among organic carbons, is remarkably increased at low load or for small-size PM, absorbing more unburned hydrocarbons. At low load, a large amount of EC1 (char-EC) is generated and the ratio of OC/EC is more than 10, while, at high load, the EC is mainly composed of EC2 (soot-EC) and the ratio of OC/EC is less than 1. Apparently, the box dimension from the morphology of diesel PM presents a positive correlation with the ratio of OC/EC. Via above external and internal characteristics, particulates exhausted from motor vehicles in the atmosphere can be beneficially identified.

Jatropha curcas biodiesel was produced via transesterification in the presence of acid catalysts. The fatty acid compositions of the biodiesel were determined using gas chromatography and mass spectroscopy. The emission features of a light-duty vehicle fuelled with Jatropha curcas methyl ester and a light-duty vehicle fuelled with petrodiesel fuel were compared in transient operating modes. In comparison with petrodiesel, under the standard test cycle, the hydrocarbon emissions, the carbon monoxide emissions and the particulate matter emissions from the vehicle fuelled with Jatropha curcas methyl ester were decreased by 57.5%, 40.8% and 42.7% respectively, owing to the 11% oxygen content in the biodiesel; however, the nitrogen oxide emissions increased by 4.9%. The regularity of the nitrogen oxide emissions in the transient operating mode are characterized by an innovative term, namely the volumetric concentration ratio of nitrogen oxide to carbon dioxide. The correlations of the transient nitrogen oxide emissions with the carbon dioxide emissions, the fuel consumptions and the operating modes are comprehensively analysed. In the constant-speed mode, the nitrogen-oxide-to-carbon-dioxide ratio becomes stabilized at a relatively low level but rises to a peak under transient conditions. This behaviour particularly occurs when the constant-speed mode shifts to an acceleration operation and when a deceleration operation shifts to a constant-speed mode. During the transient shifting stage, the nitrogen-oxide-to-carbon-dioxide ratio of the biodiesel vehicle is greater than that of petrodiesel vehicle; however, the nitrogen-oxide-to-carbon-dioxide ratios are only slightly different in the stable operating mode.