Multifunctional phase change film with high recyclability, adjustable thermal responsiveness, and intrinsic self-healing ability for thermal energy storage

Phase change materials(PCMs) present promising potential for guaranteeing safety in thermal management systems.However,most reported PCMs have a single application in energy storage for thermal management systems,which does not meet the growing demand for multi-functional materials.In this paper,the flexible material and hydrogen-bonding function are innovatively combined to design and prepare a novel multi-functional flexible phase change film(PPL).The 0.2PPL-2 film exhibits solid-solid phase change behavior with energy storage density of 131.8 J/g at the transition temperature of42.1℃,thermal cycling stability(500 cycles),wide-temperature range flexibility(0-60℃) and selfhealing property.Notably,the PPL film can be recycled up to 98.5% by intrinsic remodeling.Moreover,the PPL film can be tailored to the desired colors and configurations and can be cleverly assembled on several thermal management systems at ambient temperature through its flexibility combined with shape-memory properties.More interestingly,the transmittance of PPL will be altered when the ambient temperature changes(60℃),conveying a clear thermal signal.Finally,the thermal energy storage performance of the PPL film is successfully tested by human thermotherapy and electronic device temperature control experiments.The proposed functional integration strategy provides innovative ideas to design PCMs for multifunctionality,and makes significant contributions in green chemistry,highefficiency thermal management,and energy sustainability.

Finite time thermodynamics analysis and research of pulsating heat pipe cold storage device

Phase change energy storage technology can effectively solve the energy mismatch in space and time.There are many disadvantages of phase change materials(PCMs),such as high supercooling,phase separation and poor heat transfer performance.As a new type of heat exchange structure,pulsating heat pipe has the advantages of simple structure,high heat transfer coefficient and good economic behavior.The system efficiency can be greatly improved by using pulsating heat pipe combined with cold storage technology.A set of pulsating heat pipe type cold storage device is developed,the finite time thermodynamic analysis is carried out,and the correlation between heat pipe efficiency and power is established.The three-dimensional physical model of pulsating heat pipe is simulated and verified by experiments.The experimental results show that in the cold storage stage,with the increase of the filling rate,the greater the pressure is,the better the heat transfer effect is;in the cold release stage,with the decrease of the filling rate,the smaller the pressure is,the better the heat transfer effect is.