摘要
以柴油作原料,反应温度分别在20℃、40℃、60℃下,通过尿素络合法恒温反应4h制备石蜡,用气相色谱和差示扫描量热计(DSC)分析所制备的石蜡和市售25#、30#石蜡的正构烷烃组成和相变热并进行比较。通过比较发现,尿素络合石蜡含有多种正构烷烃,而25#、30#石蜡的组分少并集中在两种组分上,且25#、30#石蜡的相变热较高,更符合相变材料的要求。单体正构烷烃虽然满足储能要求,但其价格昂贵,因此可将烷烃组成较多的石蜡通过进一步分离使其正构烷烃组分数减少且集中在一两种组分上,来提高石蜡的相变热从而达到储能的要求。通过使用一种热力学模型预测石蜡的初始结晶点,和实验值对比证明模型能较好地预测石蜡的初始结晶点。因此可以通过调节石蜡的正构烷烃的组成及含量,使用该模型预测其初始结晶点而达到设计储能石蜡的目的。
Paraffin wax was prepared from diesel by urea adduct method at 20 ℃, 40℃, 60℃ for 4 h. The outcome and 25#. 30# paraffin waxes were analyzed in the aspects of n-alkanes distribution and phase changing enthalpy by gas chromatography and differential scanning calorimeter （DSC）. The result showed thai the paraffin waxes prepared from diesel had more n-alkane components than 25# and 30# paraffin which had higher phase changing enthalpy. Although single n-alkane is fit for PCM. it is very expensive. So by separating the paraffin wax which has n,any n-alkane components, can reduce the number of components and concentrate on one or two nalkanes, this can improve the heal changing enthalpy of paraffin wax and it can be used as PCM. A thermodynamic model was presented to predict the initial crystallization point, the predicting result accorded with the experiment data well. So it is convenient to design paraffin wax by adjusting the content of n-alkanes and using the model above to predict its initial crystallization point.
出处
《上海化工》
CAS
2008年第1期10-13,共4页
Shanghai Chemical Industry
关键词
正构烷烃
相变热
热力学
石蜡
相变材料
N-alkanes
Phase changing enthalpy
Thermodynamics
paraffin wax
PGM
