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Isothermal pyrolysis of rice husk catalyzed by iron and nickel was conducted in a microfluidized bed reactor to investigate the forming characteristics and kinetics of the main gas components. Results indicated that both Fe and Ni showed a catalytic effect on the releasing behavior of gaseous products during rice husk pyrolysis. The forming reaction rate of H2 and CO2 was significantly promoted with the addition of Fe or Ni, while that of CH4 was inhibited. For CO, Ni showed a positive effect while Fe showed a negative effect on its forming rate. The char evolution of rice husk was also influenced by the presence of Fe and Ni from the SEM-EDX and BET results. The model fitting method was used to calculate the kinetics of gas releasing to further investigate the effect of Fe and Ni, and the most probable reaction mechanism was obtained based on the relative error between experimental and calculated conversion fraction. Corresponding to the changing trend of reaction rate, the obtained activation energies f...

Co-pyrolysis behaviors of Zhundong lignite and pine sawdust under isothermal conditions were investigated with a focus on the gas releasing characteristics using a micro fluidized bed reactor. The kinetic parameters were deduced by measuring time-dependent changes in the composition of evolved gases from the pyrolysis reactions, employing the universal integral method. The gas release intensity and conversion rate of pine sawdust were quite different from those of Zhundong lignite because of the difference in chemical structure and element content. The effect of blending ratio on the degree of conversion varied significantly for different gas components; H2, CO, and CH4 conversion became quicker with an increasing biomass ratio, while the variation of CO2 was not obvious. The generally used mechanistic models for gas–solid reactions were examined as ways to interpret the experimental data, and reaction kinetics was deduced with respect to the formation of an individual gas component. The obtained activati...

This work aims to investigate the importance of biomass char and the metal oxides in the ash in tar cracking during the volatile–char interactions. Experiments were carried out in a two-stage fixed reactor, and corncob, one typical agricultural biomass rich in potassium, was chosen as raw material. Results showed that char and char-supported potassium catalysts have good activity for tar elimination due to the good absorbability of char and catalytic property of potassium. In particular, tar conversion efficiency can reach 95.8% by using 1.5 K-char catalyst at 700 °C. The reforming reactions can be significantly enhanced during the volatile–char interactions in the presence of char and char-supported potassium catalysts. As a result, the syngas yield increased significantly with increasing temperature and supported K+, particularly the combustible gases including H2, CO and CH4. Physical and chemical structure of char changed due to reforming reactions related to the carbon, while the content of potassium was almost unchanged.

Influence of potassium on the gas releasing behaviors during rice husk high-temperature pyrolysis was investigated under isothermal conditions in a two stage micro-fluidized bed reactor. Reaction kinetics for generating H2, CO, CO2 and CH4 was investigated based on the Friedman and model-fitting approaches. Results indicated that different gas species had different times to start and end the gas release process, particularly at 600 °C, representing different chemical routes and mechanics for generating these gas components. The resulting apparent activation energies for H2, CO, and CO2 decreased from 23.10 to 12.00 kJ/mol, 15.48 to 14.03 kJ/mol and 10.14 to 7.61 kJ/mol respectively with an increase in potassium concentration from 0 to 0.5 mol/kg, while that for CH4 increased from 16.85 to 19.40 kJ/mol. The results indicated that the addition of potassium could promote the generation reactions of H2, CO and CO2 while hinder the generation reactions of CH4. The pyrolysis reaction was further found to be subject to the three-dimensional diffusion model for all the samples.

Potassium is a well-known alkali catalyst in the thermal reactions of biomass. The effect of potassium on the pyrolysis behavior and kinetics of biomass was investigated through TGA and a fixed bed in this study. The addition of potassium reduced initial and peak temperature in TGA curves, promoting the decomposition process of biomass. The effect of potassium on the apparent activation energy varies at different conversion degree ( a ) and lower apparent activation energy was obtained at the initial stage ( a ⩽ 0.3) of the pyrolysis process. The influence of potassium on the volatiles releasing behavior was dependent on the amount of loading potassium. The gas yield was significantly increased with the increasing of potassium concentration when the impregnated potassium was below 0.3 mol/kg. Particularly, the yield of H 2 and CO 2 was promoted by potassium. Higher potassium content may contribute to the increase in reactivity towards tar molecules, leading to quickly decrease in tar yield. The surface chemical characteristics of char were determined by FTIR spectroscopic method. Above a certain threshold surface concentration of potassium, SEM analysis shows that agglomeration is a potential threat at high temperature, which can block the active sites and decrease the activity during biomass thermal decomposition.

Pancreatic cystic lesion (PCL) is a relatively low incidence of pancreatic disease. No clinical symptoms of PCL prevalence rate is 2.4% ~ 13.5% and has a tendency to increase with the increase of age. With the development of modern imaging technology and the improvement of people health consciousness, there has been a dramatic increase in the prevalence of PCL. PCLs involving a wide range of pathology can range from obviously benign to borderline malignant potential lesions to overt malignancy. Pancreatic cystadenocarcinoma belongs to one of the malignant tumor of PCLs, may be malignant from pancreatic cystadenoma, and it is clinically rare, accounting for only 1% of the malignant tumors of the pancreas. Preoperative diagnosis is difficult of the disease, it mostly need to postoperative pathological diagnosis. The main symptoms of pancreatic cystadenocarcinoma are dull pain or low back pain in the upper and middle abdomen, and mass in the upper abdomen. Abdominal pain is not intense, some patients only for the feeling of fullness discomfort. Other symptoms may include loss of appetite, nausea, indigestion, weight loss, jaundice, and in a few patients, gastrointestinal bleeding. In this paper, we report a rare case of pancreatic cystadenocarcinoma with a huge cystic lesion that grows rapidly in a short period of time in pregnant women, which preoperative diagnosis is considered pancreatic cystadenoma in the preoperative. Complete resection was performed and histological examination confirmed the diagnosis of pancreatic cystadenocarcinoma.

Development of latent functionally thermal fluid (LFTF) with excellent optical absorption and controllable heat transfer properties for direct absorption solar collector (DASC) is crucial in solar thermal utilization. In this study, the microcapsule, with melamine-formaldehyde (MF) resin shell and octadecane core, was prepared via in situ polymerization, as its shell was modified by reduced graphene oxide (rGO) and its core was doped with oleic acid coated Fe3O4 magnetic nanoparticles (OA-MNs). The microstructure, optical, thermal and magnetic properties of rGO modified magnetic phase change microcapsules (rGO-MPCMs) were investigated by means of various characterizations. The experimental results revealed that adding rGO substantially enhanced the thermal conductivity of magnetic phase change microcapsules (MPCMs) and only had tiny impact on the phase change behavior of MPCMs. Meanwhile, the thermal stability of octadecane in rGO-MPCMs was remarkably improved due to MF resin shell served as protective barrier. Furthermore, the rGO-MPCMs slurry exhibited better optical absorption and thermal storage capacities compared with MPCMs slurry and deionized water, thus enhancing photo-thermal conversion performance. Under an external magnetic field, the rGO-MPCMs in slurry presented excellent controllability and recyclability. Our research demonstrated that the rGO-MPCMs slurry, as a desirable working fluid, showed spacious application prospect for DASC.

High-efficiency photo-thermal conversion is an attractive approach for solar thermal energy to alleviate energy crisis. In this work, MWCNT-H2O nanofluids were prepared and its photo-thermal conversion properties were characterized. Moreover, an optical fiber as internal light source was introduced into direct absorption solar collector (DASC), in which the photo-thermal conversion performance of the stored MWCNT-H2O nanofluids was systematically explored. The experimental results showed that the photo-thermal conversion performance of MWCNT-H2O nanofluids was improved by introducing optical fiber as internal light source into the DASC and a maximum photo-thermal conversion efficiency of 65.4% was acquired at the MWCNTs concentration of 0.010 wt% and the optical fiber location of 15 mm. This study indicated that the MWCNT-H2O nanofluids applied in the DASC with optical fiber was a potential candidate for solar thermal energy.

Microalgae biofilm photobioreactors (PBRs) have been gaining more and more attention worldwide attributed to their advantages of lower water requirement and simpler harvesting process. In this work, aiming at enhancing microalgae biofilm growth and gas-liquid mass transfer based on previous biofilm PBRs, a gas-permeable membrane PBR integrated with additional rough surface (GMPBR-RS) was designed. By attaching an additional piece of stainless steel mesh onto the upper surface of the newly prepared gas-permeable membrane, the roughness of the substratum surface for Scenedesmus obliquus biofilm adhesion was enhanced and therefore resulted in a 28.27% improvement in areal biomass density of S. obliquus relative to the control PBR. Moreover, responses of S. obliquus biofilm adsorption growth and CO2 fixation in the GMPBR-RS to various liquid flow rates and gas flow rates were investigated. Notably, the maximum areal biomass density of S. obliquus biofilm and CO2 removal efficiency of the GMPBR-RS reached 31.44 g m−2 and 65.05%, respectively.

Dynamic strain measurement is rather important for the characterization of mechanical behaviors in electromagnetic forming process, but it has been hindered by high strain rate and serious electromagnetic interference for years. In this work, a simple and effective strain measuring technique for physical and mechanical behavior studies in the electromagnetic forming process has been developed. High resolution (∼5 ppm) of strain curves of a budging aluminum tube in pulsed electromagnetic field has been successfully measured using this technique. The measured strain rate is about 10(5) s(-1), which depends on the discharging conditions, nearly one order of magnitude of higher than that under conventional split Hopkins pressure bar loading conditions (∼10(4) s(-1)). It has been found that the dynamic fracture toughness of an aluminum alloy is significantly enhanced during the electromagnetic forming, which explains why the formability is much larger under electromagnetic forging conditions in comparison with conventional forging processes.

In order to research the ways of establishing holistic finite element model based on properties of joints, the vibration modal of a vertical machining center KVC1050N is analyzed using the software ANSYS and the equivalences principle of fixed, rolling and sliding joints are introduced, which are compared with the modal testing. The result shows that the FE analysis vibration modal based on characteristics of joints accords with the test modal well, and the error of natural frequency for coherent vibration modes is about 15%, depending on which it analyses how stiffness of major joints effects holistic dynamic characteristics using the theory of orthogonal test, and these provide a new method for analysis and optimal design of the vertical machining center.