Preparation Of Paraffin-based Phase Change Energy Storage Materials And Their Application

In recent years,the technical demands of thermal energy storage and temperature control domestic and abroad continues to rise,the research on the basis and application of paraffin phase change composite energy storage materials has become a technical hotspot.Paraffin phase change composite energy storage material is a functional material that encapsulates paraffin in the pore structure of regular shape or relatively fixed shape carrier and USES the latent heat of paraffin phase change to store and release heat during phase change.This paper will focus on the composite paraffin phase change energy storage material capacity,thermal efficiency and thermal stability study conducted in-depth system,using paraffin molecular structure characteristics,adopts the decompression sweating method preparation phase change paraffin wax,high latent heat value,and then with rigid polyurethane foam,polyurethane/epoxy resin respectively,fly ash as the carrier,high melting point of paraffin as phase change material,different encapsulation method of paraffin wax setting sealing,the influence of phase change composite energy storage materials,and the heat capacity,thermal efficiency and the thermal stability and so on,and finally using self-made phase change heat storage cabin,phase transition temperature of pavement unit,solar heat storage water tank,The effect of heat storage and temperature regulation of paraffin shaped phase change energy storage composite material.In the second chapter,the paraffin wax with high latent heat value and high melting point were prepared by reducing pressure and sweating.Firstly,the self-made pressure reducing and sweating forced separation device was used to find out the pressure reducing and sweating separation process parameters suitable for the production of high melting point and narrow fraction paraffin wax.TGA,GC,FT-IR,XRD and DSC were used to analyze the physical and chemical properties of the separated products.Finally,the application effect of 70?wax was investigated on the wax thermostat.The results showed that the reduced pressure sweating method could enhance the mass transfer efficiency of the sweating process,significantly increased the content of n-alkanes by22.06%,and reduce the carbon number distribution by 6%.The oil content in the product can be reduced by more than 55%effectively compared with normal sweating,so it can be used to produce wax with high melting point at about 70?and increase the yield of the product by more than 6%.?TMax?L%above 7?high melting-point wax completely conform to the requirements of the automobile engine radiator thermostat.In chapter three,rigid polyurethane foam waxed paraffin composite(PU-PCM)was prepared.Physical and chemical properties of the new material were studied.Phase change materials were added to polyurethane foam to enhance its thermoregulation function.The microstructure,chemical structure and thermodynamic properties of PU-PCM were characterized and analyzed.The thermostatic effect of PU-PCM was investigated by using the self-built paraffin phase change heat storage room.The results showed that the paraffin was firmly locked in the honeycomb pore structure of polyurethane hard foam through van der Waals force,and the apparent density increased from 0.035 g/cm~3to 0.093 g/cm~3.When the paraffin content reached by 15%,the heat capacity of PU-PCM being the maximum and no leakage occured.When the temperature on the outside wall of the heat storage cabin changes,PU-PCM wall with 15%paraffin can delay the temperature change at 1.4?/h,and the indoor temperature difference was always kept within 2?,thermal comfort is significantly improved and energy saving effect was obvious.Fourth chapter conducted a polyurethane/epoxy resin system with paraffin phase change materials synthesis technology research,synthesis of polyurethane/epoxy ternary compound paraffin composite materials(hereinafter referred to as the PUEP-PCM),as the asphalt modifier and phase transformation antifreeze bridge deck or the temperature control is the main material of composite board to carry out applied research,examined after joining the PUEP-PCM modifier and the physical properties of the asphalt and asphalt pavement thermal performance difference of melting ice and snow.The experimental results showed that paraffin wax can be uniformly dispersed in the ternary compound formed by polyurethane/epoxy resin.The asphalt with PUEP-PCM modifier maintained the thermogravimetric law of interpenetrating polymer.PUEP-PCM had no leakage phenomenon and was well sealed in the ternary compound polymer.The softening point of asphalt was increased by 40?,the penetration degree is decreased by5.8 mm,and the slowing elongation was reduced by 50%,thus extending the service life of the repaired road surface.The 28-day compressive strength and bending strength of the road surface and bridge deck with PUEP-pcm were up to 55.1 MPa and 6.55 MPa,respectively,and the structural elasticity and toughness were enhanced.The composite anti-freezing pavement board increases the temperature of the road surface by 2.3degrees Celsius,effectively improved the anti-freezing and anti-skid performance of the road surface.The fifth chapter inspected the modification effects of acid and alkali waste fly ash of power plant,the blending synthetic paraffin adsorption/fly ash composite phase change materials of technical route,using FT-IR,DSC differential scanning calorimeter,pore structure,BET method,analyzed the chemical structure,thermal properties,material of channel structure,investigated the application of this material in the solar phase change heat storage water tank.Experimental and characterization results showed that after modification of fly ash,the pore volume increased from 0.11 cm~3/g to 0.32cm~3/g,an increase of 200%.Paraffin can disperse well in the porous structure of modified fly ash,and the thermal stability of composite materials and paraffin are good.The water tank filled with 70%paraffin/fly ash composite phase-change energy storage material endured 5 min more waterproof than the ordinary water tank of the same specification,and has 3 MJ more effective release energy.Therefore,it has a good thermal application prospect in family life.