Determining V-I characteristics of energy-efficient electrostatic assisted air filtration system by utilizing the back-corona induced current model

The widely utilized high efficient particulate air filters(HEPA)and electrostatic precipitator(ESP)respectively has the shortcomings of relatively high energy consumption and low filtration efficiency.In order to overcome the disadvantages of two traditional air filtration system,electrostatic assisted air filtration system(combining HEPA and ESP)has been proven to achieve high filtration efficiency and low energy consumption simultaneously.Predicting of V-I characteristics of electrostatic filtration system with configuration of“pin to filter medium to grounded device”is very essential and challenging due to the back corona phenomenon.This study utilized the back-corona based current model to predict the V-I characteristics of electrostatic system with different filter medium types and“pin-to-filter”distances.Experiments are conducted to provide data for model validation by changing filter types and locations of discharge pin.The results indicated that both of the predicted values of total discharge current and back-corona induced current agreed well with the experimentally measured data.This validated mathematical model could be used for preliminary design of electrostatic assisted filtration system with configuration of“pin to filter to grounded device”.Based on the V-I characteristics predicted by the semi-empirical model,the electrostatic filtration efficiency could be estimated.

Air flow characteristics of an air-assisted sprayer through horizontal crop canopy

Artificially induced air currents or air-assistance to droplet spectrum produced by hydraulic nozzles not only facilitate in transporting and depositing the droplets in different parts of canopy but also reduce the application rate of chemicals.The air streams increase the velocity of smaller droplets so that extra momentum would increase impaction and improve penetration into the crop as well as mitigating the influence of wind on drift.It is necessary to quantify the airflow characteristics.But,control of climatic and other conditions in the field is very difficult.Thus,airflow characteristics study was done under controlled conditions on a horizontal simulated crop canopy.Based on this study,an airflow distribution model was developed and airflow characteristics for vegetable crops,namely,eggplant,chilli and bittergourd were predicted.The differences between predicted and actual field study values were not statistically significant.Kinetic energy of air stream dissipated with its movement from top to bottom of the canopy.The rate of kinetic energy dissipation was higher in denser canopies.Higher air velocity 15 m/s was the best as it produced maximum turbulence throughout the canopy.

Design and performance of air flow-assisted ionization imaging mass spectrometry system

The imaging mass spectrometry（IMS） technology has experienced a rapid development in recent years.A new IMS technology which is based on air flow assisted ionization（AFAI） was reported.It allows for the convenient pretreatment of the samples and can image a large area of sample in a single measurement with high sensitivity.The AFAI in DESI mode was used as the ion source in this paper.The new IMS method is named AFADESI-IMS.The adoption of assisted air flow makes the sample pretreatment easy and convenient.An optimization of the distance between the ion transport tube and MS orifice increases the sensitivity of the system.For data processing,a program based on MATLAB with the function of numerical analysis was developed.A theoretical imaging resolution of a few hundred microns can be achieved.The composite AFAI-IMS images of different target analytes were imaged with high sensitivity.A typical AFAI-IMS image of the whole-body section of a rat was obtained in a single analytical measurement.The ability to image a large area for relevant samples in a single measurement with high sensitivity and repeatability is a significant advantage.The method has enormous potentials in the MS imaging of large and complicated samples.

High-performance flexible nanocomposites with superior fire safety and ultra-efficient electromagnetic interference shielding

High-performance multifunctional polymeric materials integrated with high fire safety,excel-lent mechanical performances and electromagnetic interference(EMI)shielding properties have great prospects in practical applications.However,designing highly fire-safe and mechanically ro-bust EMI shielding nanocomposites remains a great challenge.Herein,hierarchical thermoplastic polyurethane/cyclophosphazene functionalized titanium carbide/carbon fiber fabric(TPU/CP-Ti_(3)C_(2)T_(x)/CF)nanocomposites with high fire safety and mechanical strength and toughness were prepared through the methods of melt blending,layer-by-layer stacking and thermocompression.The TPU/CP-Ti_(3)C_(2)T_(x)showed improved thermal stability.Moreover,the peak of heat release rate and total heat release of the hi-erarchical TPU sample containing 4.0 wt.%CP-Ti_(3)C_(2)T_(x)were respectively reduced by 64.4%and 31.8%relative to those of pure TPU,which were far higher than those of other TPU-based nanocomposites.The averaged EMI shielding effectiveness value of the hierarchical TPU/CP-Ti_(3)C_(2)T_(x)-2.0/CF nanocomposite reached 30.0 dB,which could satisfy the requirement for commercial applications.Furthermore,the ten-sile strength of TPU/CP-Ti_(3)C_(2)T_(x)-2.0/CF achieved 43.2 MPa,and the ductility and toughness increased by 28.4%and 84.3%respectively compared to those of TPU/CF.Interfacial hydrogen bonding in combination with catalytic carbonization of CP-Ti_(3)C_(2)T_(x)nanosheets and continuous conductive network of CF were re-sponsible for the superior fire safety,excellent EMI shielding and outstanding mechanical performances.This work offers a promising strategy to prepare multifunctional TPU-based nanocomposites,which have the potential for large-scale application in the fields of electronics,electrical equipment and 5 G facilities.

Precision orchard sprayer based on automatically infrared target detecting and electrostatic spraying techniques

There is an urgent need for new chemical application techniques and sprayers in Chinese orchard spraying.A new tractor-mounted automatic target detecting electrostatics,and air-assisted orchard sprayer was designed and developed to meet the demand of chemical pest control in orchards.This sprayer light weighted,highly efficient,reduces pesticide use and is friendly to the environment.The techniques of automatic target detecting,electrostatics,and air-assisted spraying were combined in this system.The electrostatically charged droplets are projected toward the target by the assistance of an air stream that increases the droplets penetration within canopy.Experimental results show that the new automatic target detecting orchard sprayer with an infrared sensor can save more than 50%to 75%of pesticides,improve the utilization rate(over 55%),control efficiency,and significantly reduce environmental pollution caused by the pesticide application.At the same time the key technological problems related to air-assisted low volume and electrostatic spraying were solved.