The Study Of Thermal Energy Storage Characteristics Of Paraffin/Copper Nanoparticles Composite Phase Change Materials

The phase temperature of octadecane in the paraffin is about28℃, which is applicableto heat storage system in natural environment. So select octadecane as the phase changematerials of solar chimney power plant system with vertical heat collector. Octadecanehas its advantages of high latent phase-change heat, no super-cooling and separation,stable property, non-toxic and low price. But its thermal conductivity is poor, so takeadd copper nanoparticles way to strengthen the thermal conductivity of paraffin on thebasis of the optimization of the system device structure.According to the basic theory of heat transfer and the distribution rule betweencopper nanoparticles and paraffin, a new parallel hybrid heat conduction model isestablished to calculate thermal conductivity of composite materials. The conclusionsinclude: copper nanoparticles can increase significantly the thermal conductivity ofoctadecane. With the content of copper nanoparticles increased, thermal conductivityof composite materials constantly increasing.The simulation of thermal conductivity of octadecane and composite materials aresudtied by the molecular dynamics method. The results show that: the highest thermalconductivity of octadecane is0.216W/m K when it is in the solid; the lowest is0.192W/m K when in Phase change melting state. Different contents of coppernanoparticles can make the thermal conductivity of composite material coefficientincrease differently. When the content of copper nanoparticls is1%, the thermalconductivity of octadecane is increased by17%.By the method of chemical dispersants and ultrasonic oscillation, the compositephase change materials with different volume fractions of copper nanoparticles areproduced, which are0.1%、0.2%、0.5%、1%、2%. And then thermal conductivity ismeasured with transient thermal probe method. The results show that: with the contentof copper nanoparticles increased, thermal conductivity of composite materials the firstincreases, then decreases. And the maximum value is0.277W/m K, when the content of copper nanoparticles is1%.The phase-transition latent heat、temperature and time of composite phase changematerials are measuered by differential scanning calorimetry (DSC) instrument, theresults show that: with the content of copper nanoparticles increased, bothphase-transition latent heat and phase-transition temperature are decrease,phase-transition time the first decreases, then increases. When the content of coppernanoparticles is0.5%~1%, the shortest time needed for phase, and the heat conductionperformance of composite materials is the best.Through added copper nanoparticles to strengthen the heat conductionperformance of octadecane, get more ideal results. It is significant for the study ofphase change energy-storage materials.