Effect of gas flow on the nanoparticles transport in dusty acetylene plasmas

This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to flow into the chamber from the upper showerhead electrode.The internal energy of the gas medium therein is transferred into kinetic energy so the gas advection can be triggered.This is represented by the pressure volume work term of the gas energy converse equation.The gas advection leads to the gas temperature sink at the gas inlet,hence a large gas temperature gradient is formed.The thermophoresis relies on the gas temperature gradient,and causes the profile of nanoparticle density to vary from a double-peak structure to a single-peak one.The gas advection influences the properties of electron density and temperature as well and causes the drift-ambipolar mode profile of electron density asymmetric.In the bulk region,i.e.away from the inlet,the gas advection is more like one isovolumetric compression,which slightly increases the temperature of the gas medium at consuming its kinetic energy.

The effects of dilution gas on nanoparticle growth in atmospheric-pressure acetylene microdischarges

A two-dimensional multi-fluid model is developed to investigate the effects of dilution gas on microplasma properties and nanoparticle behavior in atmospheric-pressure radio-frequency acetylene discharges.The percentage of dilution gases(argon and helium)percentage varied from 0%to 90%,with the pressure kept constant.Simulation results show that the dilution gas percentage has a significant influence on the spatial distributions of the electron density and temperature,as well as on the formation of nanoparticles in acetylene microplasmas.With increasing dilution gas percentage,the electron density profile changes continuously from being high at the edge to high in the center.A mode transition from a mixed discharge mode with bothαregime and drift-ambipolar regime intoαregime occurs,which is associated with a sudden decrease in the electron density of the presheaths and an increase in the electron temperature of the bulk plasma.The mode transition point corresponds to the lowest number density ratio of hydrocarbon ions to acetylene.The highest number density ratio is observed at a dilution percentage of 90%,and causes more effective nucleation and coagulation of nanoparticles.Furthermore,owing to the high ionization potential of helium,the transition point moves to a larger dilution gas percentage in C_(2)H_(2)/He microplasmas.Finally,the growth of nanoparticles via coagulation is studied.

Analyses on Temporal and Spatial Variation Characteristics of Erosion and Deposition in the Front Edge of Salt Marsh Wetland

Taking Yancheng Nature Reserve Salt Marsh as the research object,the remote sensing images from 2005 to 2020 were interpreted by using remote sensing and geographic information system technology.In this paper,the temporal and spatial variation characteristics of erosion and deposition in the front edge of salt marsh wetland were analyzed.The influence of sea level rise on the annual change of salt marsh area was analyzed.The characteristics of flow and sediment movement in salt marsh and the causes of erosion and deposition in front of salt marsh were analyzed.The results showed that:(1)During 2005-2007,the sea level was relatively low,and Spartina alterniflora in salt marsh expanded to the sea.Since 2007,the front edge of salt marsh wetland has coexisted with erosion and deposition.From 2008 to 2010,the front edge of salt marsh wetland once again showed a trend of comprehensive deposition to the sea side.From 2010 to 2012,the erosion of salt marsh wetland was serious.From 2012 to 2020,the front edge of salt marsh wetland in the range of 9 km south of Xinyang estuary was eroded.(2)The correlation analysis was carried out between the area of salt marsh wetland and sea level rise.Spartina alterniflora is easily affected by sea level change,owing to it having a low ecological niche.With the rise of sea level,the area of salt marsh has been decreasing since 2013.(3)In the front sea area of salt marsh wetland,the maximum velocity of the ebb and flood can reach the threshold velocity during the spring tide.The sediment starts to move at water depth of 10 m under wave actions.Owing to wave stirs up sediment and current transports the sediment,resuspended sediment causes the erosion of marsh-edge scarps.

Pricing Mechanism for Community Prosumers in Decentralized Electricity Market

A novel pricing mechanism for peer-to-peer(P2P)energy trading among the community prosumers is proposed.The prosumers are composed of the sellers with surplus energy and the buyers with insufficient energy.The buyers can adjust the energy consumption behavior based on the price and quantity of the energy supplied by the sellers.Two separate competitions exist in the trading process:1)the competition of price among the sellers;and 2)the competition of seller selection among the buyers.The price competition among sellers is modeled on the basis of optimal supply response.Based on the optimal demand response,the modeling for buyers’dynamic behaviors is used to select sellers and decide the trading quantity.Furthermore,the Stackelberg game is used to analyze the interaction between the buyers act as followers and sellers act as leaders.P2P optimal pricing is achieved by maximizing social welfare.The proposed method is applied to small community prosumers with distributed energy resources(DERs).Simulation results show that the proposed P2P energy pricing mechanism can provide significant financial benefits for the community.First,with the increase of demand,the created welfare flows to the seller as the supply is lower than the demand.Second,as the supply is exceeding the demand,the created welfare with the increase of DERs supply flows to the buyer as the DERs supply is lower,and flows to the buyer and seller as the DERs supply is higher.The results also demonstrate that:the higher the adoption of DERs,the higher the social welfare.