Computational and Experimental Study of Cooling Process in Coke Dry Quenching Experimental Shaft

Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.

Anti-blocking performance of ultrahigh-pressure waterjet assisted furrow opener for no-till seeder

No-till planting method is widely used for maize-wheat two-crops-a-year area in the North China Plain.However,cruel soil conditions,especially the large number of maize stalks which are hard to cutoff covering,often cause an unsatisfying planting quality.Based on the authors’previous investigation,ultrahigh-pressure(UHP)waterjet is capable to solve this problem and obtain qualified seedbeds.Thus,a UHP waterjet assisted furrow opener for no-till seeder was designed.Field tests showed that double-disc furrow openers worked well with UHP waterjet,since the sharpened disc blades could help to cut soil and residue,meanwhile,minimize soil disturbance.Response surface method(RSM)was used to investigate the relationship among forward speed,waterjet pressure,jet impingement angle and anti-blocking performance(stalks cutoff ratio and depth of soil cutting),and a Box-Behnken three-factor design was used to identify the optional operation parameters.A total of 17 combinations were conducted,and the results showed all three operation parameters significantly affected anti-blocking performance.Stalks cutoff ratio and depth of soil cutting increased with the increase of waterjet pressure,jet impingement angle,and decreased with the increase of forward speed.The optimization analysis indicated that when waterjet pressure was 267-280 MPa,jet impingement angle was 80.2°to 90.0°and forward speed was 4.00-4.42 km/h,the overall performance of UHP waterjet assisted double-disc furrow opener for no-till seeder was maximized.Stalks cutoff ratio could be above 95%and no blockage occurred.This study may provide a new approach and reference for the anti-blocking technology of no-tillage seeding.

Performance of waterjet on cutting maize stalks: A preliminary investigation

Large amounts of crop stalks left in the field as a result of conservation agriculture cause blockage during no-till planting.To solve this issue,pure waterjet was used to cut off the maize stalks so that the rear furrow opener could pass through without blockage.In this investigation,an experimental study on depth of cut,which was the main performance indicator of pure waterjet on cutting maize stalks,was presented.A full factorial design with 200 tests was implemented with respect to three operation parameters,that is traverse speed,waterjet pressure,and standoff distance were considered as variables.An analysis of variance(ANOVA)was carried out in order to determine the statistical significance of individual operation parameters.Using multilinear stepwise regression analysis,a model to predict the cut of depth from the predicted pure waterjet operation to cut maize stalks was then developed.All three operation parameters significantly influenced the cutting performance.Moreover,the results indicated that depth of cut increased with the increase of waterjet pressure,the decrease of traverse speed,and decrease in standoff distance.Waterjet pressure provided major contribution to depth of cut,followed by traverse speed,then standoff distance,which was demonstrated by both ANOVA and regression analysis.The experimental results showed that when the standoff distance was closer than 10 mm and waterjet pressure was 280 MPa,all maize stalks specimen could be cutoff thoroughly.With the consideration of field operating conditions,waterjet pressure of 280 MPa or higher and 10 mm to 15 mm standoff distance were recommended for maize stalks cutting.This analysis provided a realistic approach for the optimization of the ultra-high pressure pure waterjet parameters in maize stalks cutting,which could be used to relieve the occurrence of straw blockage in no-till planting.

Optimization of operating parameters of seeding device in plot drill with seeding control system

Plot drill has a significant impact on field breeding by replacing manual seeding.However,the seeding performance of plot drill needs to be further improved as the mechanical transmission method cannot work under the optimal combination of operating parameters.In this study,a cone compartment tray of sowing device was evaluated under the laboratory conditions,using a self-designed seeding control system to adjust the operating parameters.Among them,a plot seeding control system was involved that could set operating parameters through an Android terminal,which effectively reduced the difficulty of parameters adjustment.The method of central composite experiment design was employed to conduct experiments and explore the effects of experiment factors such as lifting height of storage tube(LHST),rotation speed of cone compartment tray(RSCCT),and rotation speed seed distributor(RSSD)on the seeding uniformity coefficient of variation among rows(SUCVR)and the rate of damaged seeds(RDS).For SUCVR of wheat,the results showed that the importance order of main factors from high to low was RSSD,RSCCT and LHST.And for SUCVR of buckwheat,RSCCT had the largest influence,followed by RSSD,and LHST had the smallest influence.For RDS of wheat and buckwheat,only RSSD had a very significant effect among the main factors.The experiments data of wheat indicated that when operated at 27.2 mm for LHST,4.5 r/min for RSCCT and 1169 r/min for RSSD,the sowing performance of wheat was optimal,with SUCVR and RDS values of 5.02%and 0.117%,respectively.The buckwheat seeding performance was found to be optimal when the LHST,RSCCT and RSSD were 26.5 mm,3.9 r/min and 711 r/min,and SUCVR and RDS were 4.74%and 0.113%.The seeding control system realized the electromechanical control of the seeding equipment,was convenient for parameter setting and stepless adjustment,and could be operated under an optimized combination of operating parameters.The research results could provide a reference for the performance improvement and application of plot drill.

Strontium doped electrospinning fiber membrane with antibacterial and osteogenic properties prepared by pulse electrochemical method

The osteogenic differentiation and new bone formation are commonly delayed by bacterial infection of orthopedic implants,which is urgent to be resolved quickly in the clinic.The current paper prepared a strontium-doped elec-trospinning fiber membrane with antibacterial and osteogenic properties by pulse electrochemical method.Poly-lactic acid/hydroxyapatite(PLLA/HA)composite fiber substrate was fabricated by electrospinning technology,and strontium doped SrHA/Cu/Polypyrrole(PPy)composite coating was constructed with pulse electrodeposi-tion method on its surface.The strontium doping technique,degradation of Sr^(2+)and Cu^(2+),cellular compatibility,and the antibacterial activity of the fiber membrane were examined.The results revealed that the deposition of phosphorus and calcium on composite fiber was the highest,indicating good biological activity.The release of Sr^(2+)and Cu^(2+)was stable and gradual due to the modulation of PPy.The composite fiber presented excellent antibacterial performance and the antibacterial rate was close to 100%against Staphylococcus aureus and Es-cherichia coli.Furthermore,it is conducive to the adhesion,spread,and proliferation of vascular endothelial cells and osteoblasts,namely outstanding osteogenesis and angiogenesis abilities.In conclusion,the multifunctional PLLA/HA@SrHA/Cu/PPy composite fiber membrane with good antibacterial and osteogenic activity by electro-spinning technology and pulsed electrochemical deposition method provides an effective strategy for the poor bone healing of infected bone defects.