Preparation of inorganic molten salt composite phase change materials and study on their electrothermal conversion properties

Due to their limitations in conductivity and shape stability,molten salt phase change materials have encountered obstacles to effectively integrating into electric heating conversion technologies,which are crucial in energy storage and conversion fields.In this study,we synthesized an inorganic molten salt composite phase change material(CPCM)with enhanced conductivity and shape stability using a gasphase silica adsorption method.Our findings revealed the regularities in thermal properties modulation by expanded graphite(EG)within CPCM and delved into its characteristics of electric heating conversion.The study elucidated that a conductive network is essentially formed when the EG content exceeds 3 wt%.Following the fabrication of CPCM into electric heating conversion modules,we observed a correlation between the uniformity of module temperature and the quantity of EG,as well as the distribution of electrode resistance and external voltage magnitude.Building upon this observation,we proposed a strategy to adjust the module temperature field with an electric field.Comparing the proposed direct electrical heating energy storage method with traditional indirect electrical heating methods,the energy storage rate increases by 93.8%,with an improved temperature uniformity.This research offers valuable insights for the application of molten salt electric heating conversion CPCMs.

Vibration-Induced Friction Temperature Field Analysis Under Different Working Condition of Heavy Load Bolt

Based on thermal-stress coupling analysis and material properties studies,the vibration-induced friction process of a special used heavy-load bolt has been simulated.The temperature distribution of the bolt has been calculate with heat radiation and heat convection considered.Also a solid lubricant,polytetrafluoroethylene (PTFE) has bee considered to reduce the friction heat effect.The result shows that,there are very strong heat effect while no lubracant considered,the temperature of the bolt joint increased sharply and up to 700℃,which exceed the allowable temperature range of the steel.When PTFE lubricant has been applied,the temperature of the bolt joint increased to 260 ℃,and the bolt steel can by applied in this satuation.These results provide important guidance for the bolt structure modification and material selection.