Experimental Study On Preparation And The Thermal Storage Performances Of Erythritol Composite Phase Change Material

The waste heat resources of our country are more serious at present.With the continuous development of the economy,the small distributed heating system gradually increases,causing a large number of small coal-fired boilers with low efficiency and high pollution.It not only wastes a lot of energy,but also causes serious pollution to the surrounding environment.In this context,small distributed heating system can be replaced by the mobile heat storage technology.The heat storage technology mainly includes the heat storage materials and the design of the heat accumulator.Under the certain conditions of the heat accumulator,the heat storage materials is the key factor to influence the heat storage efficiency.In this paper,the erythritol with the greater latent heat value of phase change is used as heat storage material,and its heat storage property is analyzed and studied.Through the phase change principle and characteristics of phase change materials,the experiment platform of temperature measurement is set up.According to the T-history method,the phase transition temperature of erythritol is 118?,and the degree of supercooling is 8.2?.The latent heat value of erythritol by differential scanning calorimetry was 397.5J/g.It provides reference for the follow-up study and analysis.In the case of the unsteady overcooling of erythritol,the experimental T-history method is used to analyze the results.Aluminum powder in metal particles,activated carbon and magnesium oxide in porous materials,and barium hydroxide in phase-change materials as nucleating agents are better to improve the supercooling phenomenon of erythritol.When adding 3wt% aluminum powder,the average supercooling degree of erythritol is 2.3?,adding 3wt% activated carbon,the average supercooling degree of erythritol is 0.6?,adding 3wt% magnesium oxide,the average supercooling degree of erythritol is 4.2?,adding 3wt% barium hydroxide octahydrate,the average supercooling degree of erythritol is 2.6?.The appropriate dosage was determined for the effective nucleating agent experiment,the optimum additive amount of aluminum powder is 4%,the optimum additive amount of magnesium oxide is 4%,the optimum additive amount of activated carbon is 3%,the optimum additive amount of barium hydroxide octahydrate is 2%.Finally,the stability test of the effective additive/ erythritol compound phase change material was carried out,and the thermal storage performance was stable.The thermal conductivity of erythritol is relatively low,graphite nanosheets were prepared by oxidation method.The uniform erythritol/graphite nanosheets composites with 0.1wt%,0.3wt%,0.5wt% graphite nanosheets were obtained.According to the step cooling curves,0.5wt% of graphite nanosheets can increase the thermal conductivity of erythritol by 21.6%.0.3wt% of graphite nanosheets can reduce the supercooling of erythritol by more than half.Finally,according to the characteristics of the variable temperature in the organic phase transition materials of erythritol,the main heat storage agent of erythritol was found to be suitable for the appropriate phase change temperature regulator: mannitol,stearic acid and xylitol.When mannitol,stearic acid and xylitol were used as the phase change temperature regulator of erythritol,respectively created with 80? to 158?,53? to 118? and 68? to 118? phase transition temperature range of phase change heat storage materials,it can meet different industrial needs.