Study On Scale-up Process Of Preparation Of Polystyrene-Paraffin MEPCM

Phase change material(PCM)undergoes a phase change process when the external temperature increases and decreases,and this process is accompanied by a change in energy.Because PCM has the characteristics of maintaining constant temperature and storing energy,it is applied in many aspects,but there are problems such as volume loss and direct contact with the surrounding environment during use,and the application of PCM is limited.Phase change energy storage microcapsules(MEPCM)are formed by covering specific PCM with polymers or inorganic compounds by physical or chemical methods to form stable particles.The shell layer of the particles separates the PCM from the surrounding medium to avoid reactions,and at the same time control the volume loss of the phase change process,thereby improving the use efficiency and having broad application prospects.At present,the textile and construction fields are combined with MEPCM to make efficient use of energy.In the industrial field,a gas adsorbent is used in combination with PCM,and the energy of the gas adsorption and desorption processes is stored and released,so that the energy can be reasonably and fully utilized.Polystyrene shell polymerized with styrene(St)as a monomer has the characteristics of tight encapsulation,light weight,easy to transport,and high temperature resistance.Therefore,polystyrene is selected as the shell;Large characteristics,so paraffin was selected as the nuclear body.In this experiment,polystyrene-paraffin MEPCM was prepared,and its latent heat value was maximized,and the particle size was consistent with the use.Then,the small scale experiment is enlarged to explore the stability of the scale-up process,and a simple scale-up experiment route is concluded.In this experiment,polystyrene-paraffin wax was prepared by using suspension polymerization method with polyvinyl alcohol(PVA)as dispersant,divinylbenzene(DVB)as cross-linking agent,and azobisisobutyronitrile(AIBN)as initiator.MEPCM.A small-scale experiment was carried out in a 500 mL three-necked flask.The effects of different stirring speeds,dispersant ratio,core-wall ratio,and oil-waterratio on the microcapsules were determined,and the best preparation route for smallscale experiments was determined.According to the small-scale experiment,the reaction equipment was enlarged by 20 times,and the amplification experiment was performed in a 10 L reactor.The effects of different stirring speeds,dispersant ratio,core-wall ratio,and oil-water ratio on the production of microcapsules were again investigated.To determine the best preparation route for scale-up experimental microcapsules.The obtained microcapsules were characterized by infrared,particle size,calorimetry and other tests.The microcapsules obtained from the pilot test and the scale-up experiment were compared,and the influence of different influencing factors on the microcapsules was analyzed.The polystyrene-paraffin MEPCM prepared in this experiment has good sphericity,uniform particle size distribution,and good thermal stability.In the smallscale experiment,the best preparation route was determined as follows: dispersant accounts for 12%,core-wall ratio 1:2,oil-water ratio 1:20,and stirring speed 300 rpm.Under these conditions,the microcapsules had a particle size of 160.8 ?m and a latent heat value of 31.56 J / g.The optimal preparation route determined in the scale-up experiment is: dispersant accounts for 12%,core-wall ratio 1: 2,oil-water ratio 1:7,and stirring speed 600 rpm.Under these conditions,the size of the microcapsules prepared by the scale-up experiment is 120 ?m,the latent heat value is 45.89 J/g,and the yield is 74.3%,which is consistent with the use in the industrial field.The reaction scale is enlarged,the total amount of material is increased,and the reaction system involves complex factors such as surface tension,turbulent flow force,and viscous stress.Therefore,similar small scale experiments and scale-up experiments cannot obtain similar MEPCM under the same conditions.Different parameter conditions have different degrees of impact on small scale experiments and scale-up experiments.The feasible methods for direct scale-up of small scale experiments need further investigation,but scale-up experiments can be performed for the preparation of MEPCM.The scale-up experiments can produce excellent sphericity,heat Microcapsules with good stability and particle size.The cost calculation of the MEPCM process for the scale-up experiment was performed,and the cost included the material cost and power consumption cost of the process,whichwas 248.05 yuan/kg.