储能充填体相变前后传热性能及强度特征

Heat transfer performance and strength characteristics of energy storage filling body before and after phase transformation

目前,深井高温问题越来越突出,在充填体中加入相变材料来降低地温是解决深井高温问题的新思路。采用石蜡和CaCl_(2)·6H_(2)O制备新型复合相变材料,通过差示量热扫描仪、扫描电子显微镜、电液伺服岩石压力试验机和数值模拟等手段,研究含石蜡-CaCl_(2)·6H_(2)O充填体的相变前后的抗压强度与传热性能。研究结果表明:石蜡与CaCl_(2)·6H_(2)O复合后不发生化学反应,石蜡-CaCl_(2)·6H_(2)O不溶于水最佳复合质量比为3꞉2;石蜡-CaCl_(2)·6H_(2)O经济成本较低,在常用相变材料中经济排名靠前;加入石蜡-CaCl_(2)·6H_(2)O后充填体的抗压强度降低12.95%,石蜡-CaCl_(2)·6H_(2)O发生相变后,强度降低37.65%,但充填体的热量吸收能力提高79.60%;含石蜡-CaCl_(2)·6H_(2)O的充填体试样导热系数下降,在石蜡−CaCl_(2)·6H_(2)O相变阶段有温度响应滞后现象,温度等值线附近内部热流量方向在石蜡-CaCl_(2)·6H_(2)O未发生相变时指向石蜡-CaCl_(2)·6H_(2)O。新型石蜡-CaCl_(2)·6H_(2)O复合材料经济成本低,虽然加入充填体会降低充填体的抗压强度,但是能够大幅度提高充填体对热量的吸收。

At present,the problem of high temperature in deep wells is becoming more and more prominent,and adding phase change materials to the filling body to reduce the ground temperature is a new idea to solve the problem of high temperature in deep wells.A new composite phase change material was prepared by paraffin and CaCl_(2)·6H_(2)O.The compressive strength and heat transfer performance of paraffin−CaCl_(2)·6H_(2)O filling body before and after phase change were studied by means of differential scanning calorimetry,scanning electron microscopy,electro-hydraulic servo rock pressure testing machine and numerical simulation.The results show that there is no chemical reaction between paraffin wax and CaCl_(2)·6H_(2)O,and the best mass ratio of paraffin−CaCl_(2)·6H_(2)O insoluble in water is 3꞉2.The economic cost of paraffin−CaCl_(2)·6H_(2)O is low,and it ranks in the front in the common phase change materials.After adding paraffin−CaCl_(2)·6H_(2)O,the compressive strength of the filling body decreases by 12.95%.After the phase change of paraffin−CaCl_(2)·6H_(2)O,the strength decreases by 37.65%,but the heat absorption capacity of the filling body increases by 79.60%.The thermal conductivity of the filling body sample containing paraffin−CaCl_(2)·6H_(2)O decreases,and there is a temperature response lag phenomenon in the phase transition stage of paraffin−CaCl_(2)·6H_(2)O.The direction of the internal heat flow near the temperature contour points to paraffin−CaCl_(2)·6H_(2)O when the phase transition does not occur.The new paraffin−CaCl_(2)·6H_(2)O composite material has low economic cost.Although the addition of filling material reduces the compressive strength of the filling body,it can greatly improve the heat absorption of the filling body.