Theoretical study of gas hydrate decomposition kinetics: model predictions.

In order to provide an estimate of intrinsic gas hydrate dissolution and dissociation kinetics, the Consecutive Desorption and Melting Model (CDM) was developed in a previous publication (Windmeier, C.; Oellrich, L. R.

Theoretical study of gas hydrate decomposition kinetics--model development.

In order to provide an estimate of the order of magnitude of intrinsic gas hydrate dissolution and dissociation kinetics, the "Consecutive Desorption and Melting Model" (CDM) is developed by applying only theoretical considerations. The process of gas hydrate decomposition is assumed to comprise two consecutive and repetitive quasi chemical reaction steps. These are desorption of the guest molecule followed by local solid body melting.

NMR measurements of gaseous sulfur hexafluoride (SF6) to probe the cross-linking of EPDM rubber.

The effects of embedding gaseous SF6 into EPDM rubber were investigated using NMR methods. It was found that observed sorption and desorption processes follow the behavior of the dual mode sorption model. A strong correlation was found between EPDM cross-linking and transversal relaxation time of embedded SF6.

NMR investigation of gaseous SF6 confinement into EPDM rubber.

The confinement process of gaseous sulphurhexafluoride (SF6) in ethylene-propylene-diene (EPDM) rubber was investigated by spectroscopic and spatially resolved NMR techniques. A strong elongation of T1 relaxation time of SF6 and a decrease of the diffusion coefficient were found. A possible explanation may be the strong restriction of molecular mobility due to interactions between SF6 and active centers of the EPDM.

Application of magnetic resonance imaging to the investigation of the diffusivity of 1,1,1,2-tetrafluorethane in two polymers.

In order to evaluate the suitability of a polymer as a sealing material for certain working fluids used in process plants, information about the fluid diffusivity into the polymer or the polymer permeability to the fluid is a prerequisite. The fluid of interest in the present work is 1,1,1,2-tetrafluorethane, CH(2)FCF(3), a partly fluorinated hydrocarbon (HFC) commonly known as refrigerant R134a. HFCs are increasingly used in refrigeration, air conditioning, and heat pump applications as substitutes for the chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) that are believed to be responsible for ozone depletion in the stratosphere.