DSC法测定醋酸-水溶液的比热

利用差示扫描热量计(DSC)测定了醋酸水溶液在温度范围为293.15~359.15K和整个组成范围下的比热,并把比热的测量值与文献值进行了比较, 实验的测量误差小于±2%, 测得的醋酸-水的比热数据完全能满足工程设计的需要。同时把醋酸-水的比热与组成与温度进行了关联,并利用最小二乘法回归出所提方程中的参数,最后导出了一个计算Cp的多项式方程,此方程中既包含温度又包含组成,因此利用此方程可以计算醋酸-水体系在测定温度和组成下的Cp。把用该方程的计算值与实验值进行了比较,117个数据点的总绝对平均相对误差为0.54%。所提方程可应用于对苯二甲酸生产中换热器的设计及相关体系热量平衡的计算,具有实用意义。

The Specific Heats of Aqueous Mixtures of Acetic Acid with Water Measured with DSC

The specific heats of aqueous mixtures of acetic acid with water were measured with a differential scanning calorimeter (DSC) at temperature from 293.15K to 353.15K over the entire concentration. The results were compared with data published in the literature. The error of the measured heat capacities is less than ?%. The specific heats presented in this study are of sufficient accuracy for engineering-design calculation. At the same time, the specific heats were correlated as function of composition and temperature. The coefficients in the correlated equations were obtained by a least-squares regression method. At last, one polynominal equation for calculating the heat capacities were derived, which was composed of temperature and composition. By this Eq., the heat capacities CP can be calculated at different temperature and mass fraction. The calculated values have been compared with experimental data. The average absolute percentage deviation of 117 data points is 0.54%. The proposed equation can be used for the processing design of the heat exchanger and heat balance in p-xylene production.