Eugeniya Iskrenova - Solvent effects in the thermal decomposition reaction of ammonium carbamate: A computational molecular dynamics study of the relative solubilities of CO2 and NH3 in water, ethylene glycol, and their mixtures

Version 4

      Publication Details (including relevant citation   information):

      Abstract:

      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 CO2 and NH3 in the solution. We present   a low-cost computational procedure for relative solubility   evaluation that can be used in a broader engineering design   context.

      Address (URL): http://www.sciencedirect.com/science/article/pii/S0017931015312473