流动反应器流量调节式量热方法模拟

Simulation of flow-regulated calorimetry in flow reactor

面向连续流动条件下化学反应放热的测量需求,针对其量热方法开展研究。首先,根据流体流动状态及管路传热原理建立连续流动反应系统模型。其次,设计一种应用于流动状态下的量热方法,通过热平衡理论推导出温度信息与质量流量之间的线性函数关系,其斜率与截距中包含反应热力学信息,利用不同流量下多组实验的温度数据进行线性拟合,求取反应焓,针对管路内存在温度分布的情形,引入温度分布分段的计算方式。最后,模拟研究流量调节步长和分段计算步长对量热结果的影响。结果表明:面对多种放热工况,反应焓计算结果的误差在5%以内,随着流量调节步长和计算步长值的增加,计算结果误差增大。综合研究结果,在方法应用时,流量调节步长的建议值应在1—2 mL/min之间,计算步长的建议值应在0.005—0.01 m之间。

A calorimetry was studied in order to meet the needs of measuring the heat release of chemical reactions under continuous flow conditions.Firstly,a continuous flow reaction system model was established based on the fluid flow state and the heat transfer principle of tube.Secondly,a calorimetry under flow conditions was designed,the linear function relationship between temperature information and mass flow rate was derived by heat balance theory,the slope and intercept contain the thermodynamic information of the reaction.The temperature data of multiple sets of experiments under different flow conditions were linearly fitted to obtain the reaction enthalpy.In view of the temperature distribution in the reactor,the calculation method of segmenting temperature distribution was used.Thirdly,the effects of flow rate regulated step value and calculated step value on the measurement results of this method were simulated and analyzed.The results show that the relative error of the calculation results is within 5%under a variety of exothermic conditions.With the increase of flow rate regulated step value and calculated step value,the error of the calculation results increases.Combined with the research findings of this study,when applying this calorimetry,the recommended flow rate regulated step value for multiple groups of experiments should be between 1-2 mL/min,the recommended calculated step value should be between 0.005-0.01 m.