首页> 外文期刊>International Journal of Heat and Mass Transfer >Solvent effects in the thermal decomposition reaction of ammonium carbamate: A computational molecular dynamics study of the relative solubilities of CO_2 and NH_3 in water, ethylene glycol, and their mixtures
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Solvent effects in the thermal decomposition reaction of ammonium carbamate: A computational molecular dynamics study of the relative solubilities of CO_2 and NH_3 in water, ethylene glycol, and their mixtures

机译:氨基甲酸铵热分解反应中的溶剂效应:计算分子动力学研究CO_2和NH_3在水,乙二醇及其混合物中的相对溶解度

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The endothermic decomposition of ammonium carbamate has been proposed as a novel heat sink mechanism for aircraft thermal management (Johnson et al., 2012). The products of the reversible decomposition are carbon dioxide and ammonia which need to be efficiently removed from the carrier fluid in order to better control the reaction and thus the heat transfer. Molecular dynamics simulations can provide insight into the transport properties of carbon dioxide and ammonia in the carrier fluid. In this work, extensive classical non-reactive molecular dynamics simulations were carried out to explore the solvent effects in the thermal decomposition reaction of ammonium carbamate by studying the temperature and concentration dependence of relative solubility and diffusivity of carbon dioxide and ammonia in water, ethylene glycol, and their mixtures at standard temperature and pressure and at the elevated temperature of the thermal decomposition reaction of ammonium carbamate. This comparative study shows that ammonia is more soluble than carbon dioxide in either water or ethylene glycol and that both carbon dioxide and ammonia are more soluble in ethylene glycol than in water. Our simulations of water-ethylene glycol mixtures show that increasing the molar fraction of ethylene glycol leads to increased solubility of carbon dioxide and ammonia in the mixture. Even though this is a non-reactive study, it is able to capture the general solubility trends. Accounting for the reactions of carbon dioxide and ammonia in the solution would further amplify the observed trends by amplifying the retaining of CO_2 and NH_3 in the solution. We present a low-cost computational procedure for relative solubility evaluation that can be used in a broader engineering design context.
机译:氨基甲酸铵的吸热分解已被提出作为一种用于飞机热管理的新型散热机制(Johnson等,2012)。可逆分解的产物是二氧化碳和氨,它们需要从载液中有效地除去,以便更好地控制反应并因此控制热传递。分子动力学模拟可以深入了解载液中二氧化碳和氨的传输特性。在这项工作中,通过研究二氧化碳和氨在水,乙二醇中的相对溶解度和扩散率的温度和浓度依赖性,进行了广泛的经典非反应分子动力学模拟,以探讨氨基甲酸铵热分解反应中的溶剂效应。 ,以及它们的混合物在标准温度和压力下以及在高温下氨基甲酸铵的热分解反应。这项比较研究表明,氨在水中或乙二醇中的溶解度均比二氧化碳高,并且二氧化碳和氨在乙二醇中的溶解度均高于水。我们对水-乙二醇混合物的模拟表明,增加乙二醇的摩尔分数会导致二氧化碳和氨在混合物中的溶解度增加。即使这是一项非反应性研究,也能够捕获总体溶解度趋势。考虑到溶液中二氧化碳和氨的反应,将通过扩大溶液中CO_2和NH_3的保留来进一步放大观察到的趋势。我们提出了一种用于相对溶解度评估的低成本计算程序,该程序可以在更广泛的工程设计环境中使用。

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