热泵中氨基甲酸铵分解反应特性及反应器结构优化

doi:10.16085/j.issn.1000-6613.2022-1903

摘要/Abstract

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

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

中图分类号:

TB657

刘炫麟, 王驿凯, 戴苏洲, 殷勇高. 热泵中氨基甲酸铵分解反应特性及反应器结构优化[J]. 化工进展, 2023, 42(9): 4522-4530.

LIU Xuanlin, WANG Yikai, DAI Suzhou, YIN Yonggao. Analysis and optimization of decomposition reactor based on ammonium carbamate in heat pump[J]. Chemical Industry and Engineering Progress, 2023, 42(9): 4522-4530.

图/表 20

图1 基于AC的分解反应特性研究系统1—跑道形螺旋管；2—恒温水浴；3—废液储液罐；4—废气吸收器；5—溶液泵；6—溶液储液罐；7—温度传感器

表1 实验仪器与精度

参数	仪器名称	型号	精度
温度	热电偶	K型	温度精度±0.5℃
水侧流量	Darhor流量计	DFA-15T	流量精度±4%
溶液侧流量	杭州逸控微小流量计	GICAR-8111	流量精度±2%
温度	安捷伦数据采集仪	Agilent 34970A	温度精度0.03℃

图2 跑道形螺旋管物理模型示意图

表2 模型验证结果对比

网格数	溶液出口温度/℃	出口AC 质量分数/%	时间步长 /s	溶液出口温度/℃	出口AC 质量分数/%
585418	51.36	94.83	0.01	51.07	94.55
1203113	51.17	94.68	0.05	51.04	94.56
3233948	51.04	94.56	0.10	51.04	94.56
6927497	50.97	94.50	0.50	49.00	94.80

图3 实验与模拟结果对比

图4 200s时沿程溶液温度分布规律

图5 200s时沿程AC质量分数分布规律

图6 不同溶液浓度对分解反应速率及平均转化率的影响

图7 不同溶液流速对反应速率及转化率的影响

图8 不同热源温度对反应速率及转化率的影响

图9 管形结构示意图

图10 不同管型沿程分布与平均转化率对比

图11 不同管型反应器内湍流强度对比

图12 螺旋管反应器内部温度分布随时间变化云图

图13 螺旋管反应器内部AC质量分数分布随时间变化云图

表3 实验设计参数设置

序号	因素1	因素2	因素3	序号	因素1	因素2	因素3
序号	螺旋半径 /mm	螺旋管直径 /mm	螺旋圈数	序号	螺旋半径 /mm	螺旋管直径 /mm	螺旋圈数
1	30	8	30	10	50	12	15
2	70	8	30	11	50	8	45
3	30	12	30	12	50	12	45
4	70	12	30	13	50	10	30
5	30	10	15	14	50	10	30
6	70	10	15	15	50	10	30
7	30	10	45	16	50	10	30
8	70	10	45	17	50	10	30
9	50	8	15

图14 螺旋半径与管直径对平均转化率的交互影响

图15 螺旋半径与螺旋数对平均转化率的交互影响

图16 管直径与螺旋数对平均转化率的交互影响

表4 螺旋管反应器优化结果

优化

螺旋半径

/mm

螺旋管直径

/mm

螺旋圈数

平均转化率模型

预测值/%

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