Simulation of PCM melting enhancement in heat storage units with self-driven flexible fins
Heat storage technology of phase change materials(PCMs)is essential for thermoelectric decoupling and deep peak regulation in thermal power plants,playing a significant role in promoting energy transformation.However,the low thermal conductivity of PCMs poses a major challenge for the rapid response of heat storage systems.An effective solution to optimize PCM thermal storage systems is the use of fins.Herein,we propose a novel approach where flexible fins serve as a strengthening component to improve the melting process.We studied the melting process and strengthening mechanism of the flexible fin PCM heat storage unit both numerically and theoretically,using the enthalpy porosity method and a fluid-structure coupling model.Our findings revealed three distinct stages in the melting process:the initial melting state,mid-term melting stage,and final melting stage.These stages were differentiated based on the melting rate.The flexible fin enhanced the melting process during the initial and mid-term melting stages,significantly increasing the melting rate of the PCM.This effectively shortened the total heat storage time.The flexible fin was deflected to store elastic strain energy.This enabled energy conversion between the elastic strain energy of the fin and the kinetic energy of the fluid through reciprocating motion.The swinging motion of the flexible fin not only increased the flow rate of the liquid phase but also hindered the merging of the spiral vortex.As a result,the higher heat convection capacity of the PCM in the flexible fin heat storage unit enhanced the melting process.This paper presents a new perspective on enhancing the PCM heat storage unit.It improves the thermal response capacity of finned heat storage units,providing a theoretical foundation for the development of flexible modification technology in cogeneration.
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