Study Of Heat Transfer Enhancement Method For Shell-tube Latent Heat Thermal Energy Storage Unit

The technology of latent heat thermal energy storage(LHTES)is used to store or release energy by phase change process of phase change materials(PCMs),which has the advantages of high energy storage density and constant operating temperature.It has great application potential in solar energy storage,power grid peak shaving,building energy storage,waste heat recovery,thermal management of electronic devices and so on.However,most phase change materials suffer from poor thermal conductivity,resulting unsatisfactory heat transfer rate of LHTES device.Present work adopts Enthalpy-Porosity Method to study the phase change character in LHTES devices and heat transfer ways by numerical approach.The main research contents and conclusion are as below:(1)The melting enhancement effect of T-shaped fins and rectangular fins in horizontal shell-tube LHTES device was compared,and the influence of fin volume and heating temperature on melting was analyzed.Finally,the influence of T-shaped fin parameters on melting enhancement effect was studied.The results show that T-shaped fins have better melting enhancement effect on PCM near shell than rectangular fins,and the complete melting time can be reduced by 47.0%.(2)The combinational fins combined by longitudinal and annular fins were designed to improve the heat transfer of vertical shell-tube LHTES device.Their melting and solidification enhancement effect were compared with using only longitudinal fins and annular fins.The influence of combinational fin parameters on melting enhancement effect was also studied.The results show that the melting enhancement effect of combinational fins is better than longitudinal fins and annular fins,but the solidification enhancement effect is only greater than longitudinal fins.Compared with longitudinal and annular fins,the optimal combinational fins reduce melting time by 31.0% and 21.2% respectively.(3)Circumferential arrangement of multiple PCMs was proposed,which was combined with fins to further enhance the heat transfer of horizontal shell-tube LHTES device,and the fin distribution was optimized.The results show that the multiple PCMs with circumferential arrangement have shorter melting and solidification times than the single PCM.The optimal arrangement of multiple PCMs have 13.4% less melting-solidification time than the optimal arrangement of single PCM.