Abstract:

As a promising material, ammonium carbamate can be decomposed under the temperature from 20℃ to 100℃, and the reaction enthalpy reaches the high value of 2010kJ/kg. The effects of various conditions on the decomposition process of ammonium carbamate were discussed, such as solution concentration, flow rate and the temperature of heat source. Results showed that the higher temperature of heat source and the longer residence time contributed to a higher rate of reaction conversion and decomposition. But the solution concentration was less sensitive to decomposition process. The average conversion rate and the reaction rate in the research range of flow rate were increased by 5—11 times and 2—4 times, respectively. And the upgrade of heat source temperature contributed to a 2—4 times increase in the average conversion rate. Based on the analysis, numerical simulation and response surface analysis were used to optimize the structural parameters of the reactor, such as spiral radius, tube diameter and the number of turns. After structure optimization, the average conversion rate could be increased to 50.3%, and a reactor structure suitable for AC decomposition in heat pump conditions was finally obtained.

Key words: reactors, reaction characteristics, numerical simulation, optimal design, ammonium carbamate, heat pump

摘要：

化学热泵可以高效地对低品位热进行提质，特别是在高温热泵方面比常规热泵系统更具独特的优势。氨基甲酸铵（AC）可以在20~100℃之间发生分解反应，且反应焓高达2010kJ/kg。本文对热泵工况下氨基甲酸铵/乙二醇溶液分解反应器进行了模拟，研究了热泵工况下不同反应条件（溶液浓度、溶液流速、热源温度）对分解过程的影响，并对AC分解反应器的管形和结构进行优化分析。结果表明热源温度越高，停留时间越长，平均转化率和反应速率越高，而溶液浓度对分解反应过程产生的影响不大。流速研究范围内平均转化率提高了5~11倍，反应速率提高了2~4倍，热源温度研究范围内平均转化率可提高2~4倍。基于参数影响规律，利用数值模拟和响应曲面分析优化了反应器的结构参数，如螺旋半径、螺旋管直径和螺旋圈数等。结构优化后，平均转化率提高至50.3%，最终获得了适用于热泵工况AC分解的反应器结构，为搭建基于氨基甲酸铵的热泵系统奠定了基础。

关键词: 反应器, 反应特性, 数值模拟, 优化设计, 氨基甲酸铵, 热泵