Preparation, Structure And Performance Of Modified Wood-based Composite Phase Change Energy Storage Material

Organic solid-liquid phase change materials have many limitations in the field of building energy conservation due to their own shortcomings.In order to solve the problem of single phase transition temperature and easy leakage,two groups of binary composite phase change materials suitable for building energy conservation were prepared by using lauric acid（LA）,paraffin wax（PW）and tetradecanol（TD）,and the binary composite phase change material is shaped and packaged using wood flour（WF）,modified wood flour（DWF）and carbonized wood flour（CW）as carrier materials to solve the leakage problem of phase change material,and improve the thermal conductivity of the composite phase change material.Then,Three wood based composite phase change materials were selected to prepare phase change energy storage boards,and their ability to regulate indoor temperature was compared and analyzed.The main contents of this paper are as follows:（1）The low eutectic ratios of LA-PW and LA-TD binary mixtures were determined to be87:13 and 45:55,respectively,by step cooling curve method.And the latent heat of phase transformation is 185.5 J/g and 125.89 J/g,respectively.Using a mixed solution of Na OH and Na₂SO₃ to obtain delignified wood powder.The pore volume of DWF and WF is 0.008955cm³/g and 0.01049 cm³/g,respectively,which increases the pore volume of DWF by 17.16%.DWF has a richer pore structure and better adsorption capacity,resulting in a 50%adsorption capacity for LA-PW and LA-TD by DWF,which is 10%higher than that of WF.The thermal conductivity of LA-PW/DWF and LA-TD/DWF are 0.3762 W/m·k and 0.3580 W/m·k,respectively.The phase transition temperatures are 40.86℃and 19.68℃,respectively,and the latent heat of phase transition is 88.86 J/g and 62.31 J/g,respectively,which are 33.61%and26.18%higher than LA-PW/WF and LA-TD/WF,respectively.（2）The carbonized wood powder（CW）prepared by pyrolysis at high temperature was found to have the largest pore volume at a carbonization temperature of 1000℃,with a value of 0.1635 cm³/g.The adsorption capacity of CW1000 for LA-PW and LA-TD reaches 50%and60%,respectively,and can better encapsulate phase change materials.The latent heat of phase transformation for LA-PW/CW1000 and LA-TD/CW1000 is 88.63 J/g and 71.08 J/g,respectively.In addition,the undercooling of LA-PW/CW1000 is 1.95℃lower than that of LA-PW,while that of LA-TD/CW1000 is 3.33℃lower than that of LA-TD.The thermal conductivity of LA-PW/CW1000 and LA-TD/CW1000 are 0.4823 W/m·k and 0.4762 W/m·k,respectively,which are 67.05%and 23.59%higher than those of LA-PW and LA-TD,respectively.LA-PW/CW1000 exhibits better thermal cycle stability over 200 cycles.（3）The phase change energy storage board is prepared using LA-PW/WF,LA-PW/DWF,and LA-PW/CW1000 as raw materials,and applied to the thermal insulation layer of building exterior walls to improve the thermal insulation performance of building exterior envelope structures.The thermal comfort duration of WF phase-change energy storage board,DWF phase-change energy storage board and CW1000 phase-change energy storage board as internal insulation is 3876s,3915s and 2971s respectively,which is 113.2%,115.3%and 63.4%higher than that of high-density foam board.When the phase-change energy storage board is used as external insulation,the thermal comfort duration is 3544s,4078s and 2106s respectively,which is 1726s,2260s and 288s more than the high-density foam board.Therefore,DWF phase change energy storage boards exhibit good thermal insulation effects when used as internal and external insulation,while WF and CW1000 phase change energy storage boards can effectively control indoor temperature fluctuations when used as internal insulation layers.