Design And Preparation Of Dry Water Fire Extinguishing Agent And Study On Fire Extinguishing Efficiency Of Lithium Battery

Dry water is a water-rich material formed by encapsulating micro-water droplets by a coating layer of nano-scale silica particles,and is a dry powder-like water-rich material.The internal water can be released under high temperature or external force.And because the dry water powder has fluidity and dispersibility similar to solid particles,it has huge potential application value in the field of flame retardant and fire extinguishing.This paper takes dry water fire extinguishing agent as the research object.By studying the influence of three parameters of different solid-liquid ratio,mixing speed and mixing time on the process of preparing dry water fire extinguishing agent using high-speed mixer,the preparation process parameters of dry water fire extinguishing agent are optimized and prepared basic dry water fire extinguishing agent coated with pure water.At the time,the basic formula of the dry water fire extinguishing agent was designed and optimized by adding different fire extinguishing components and gel agents,and 7 kinds of modified dry water fire extinguishing agents were prepared according to the new functional formula series.Then,the basic characteristic parameters such as particle size,bulk density,fluidity,water retention and pressure resistance of the prepared dry water fire extinguishing agent were characterized.Finally,for lithium ion battery fires,a self-designed fire extinguishing experiment platform was used to carry out fire extinguishing efficiency experiments for all 8 dry water fire extinguishing agents.The results show that the dry water fire extinguishing agent can work together through a variety of fire extinguishing mechanisms,and has a good fire extinguishing effect on lithium battery fires.First of all,the design and preparation of dry water fire extinguishing agent and parameter optimization experimental research were carried out.It was found that the dry water fire extinguishing agent prepared under the process parameters of solid-liquid ratio of 1:10,stirring speed of 4000 r/min,and stirring time of 180 s has a better,uniform shape and a more stable structure.In order to improve the fire extinguishing effect of the dry water fire extinguishing agent,modified additives were added and the formulation was designed to successfully prepare 7 modified dry water fire extinguishing agents,all of which have a stable and good core-shell structure.Secondly,the basic storage and transportation performance characterization research of dry water fire extinguishing agent was carried out.The particle size distributions of the 8 dry water fire extinguishing agents prepared in the experiment are all between 0 and 400 μm,and the addition of gelling agent makes the particle size distribution moderately shifted to the direction of large particle size.The bulk density of dry water fire extinguishing agent is between 0.3480 g/m L～0.4373 g/m L,and the fluidity is slightly lower than that of ordinary dry powder fire extinguishing agents.Among them,ADP dry water fire extinguishing agent has the best fluidity.The addition of gelling agent can delay the evaporation of the dry water fire extinguishing agent and increase the water retention capacity of the dry water fire extinguishing agent at 50 ℃.The dry water fire extinguishing agent has a low damage rate under1.0 MPa pressure,and the addition of gel can significantly improve its pressure resistance,so that the damage rate under 1.2 MPa is still within the acceptable range.Finally,an experimental study on the fire extinguishing effectiveness of dry water fire extinguishing agents on lithium battery fires was carried out.Under the experimental conditions,8 kinds of self-prepared dry water fire extinguishing agents and commercially available ABC dry powder fire extinguishing agents can effectively extinguish open flames of lithium batteries without re-ignition.Among them,the ADP gel dry water fire extinguishing agent has the best fire extinguishing effect,and its main fire extinguishing mechanism is a combination of multiple fire extinguishing mechanisms.This kind of dry water fire extinguishing agent has a certain viscosity,it can adhere to the surface of the battery when it is sprayed to the surface of the battery,and it is not easy to fall off,forming a stable isolation layer,which can not only play the role of oxygen barrier and suffocation,but also evaporate and absorb heat to cool down,and its internal fire extinguishing components also play a chemical inhibitory effect.