A mathematical steady-state modeling framework for the isothermal operation of a membrane reactor for methane steam reforming is developed, and a comparative performance assessment of the catalytic membrane reactor (CMR) versus a conventional packed bed reactor (PBR) is accordingly conducted. A detailed literature benchmarking suggests that the models developed in the present study predict total methane conversion levels within 99% of the experimental values reported in the literature. The proposed Pd-and Pd/Au-based CMR model is utilized for the aforementioned performance analysis under a broad range of reactor operating conditions such as temperature (350-750 C), pressure (2-30 bars), steam to methane ratio (1-15), membrane thickness (1-50 mm), and permeate-side sweep ratio (1-100). In all simulation runs conducted, the superior performance of both the Pd-and Pd/Aubased CMR over the PBR was amply demonstrated. Furthermore, within the proposed CMR modeling framework, an index-based analysis is conducted that concretely quantifies progress towards the attainment of key process intensification objectives. In particular, by appropriately defining the D-index, which explicitly captures potential performance and process intensification benefits associated with attainable total CH 4 conversion levels under different reactor operating conditions, it is shown that the optimum CMR performance is achieved at high pressure and low temperature operating conditions, which was particularly suitable for the attainment of key process intensification objectives as well as optimum performance target levels.

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The present paper explores the effects of different risk incidents on a Transportation Model developed for HazMat (Hazardous Materials) shipments. The particular objective of this study is to elucidate the effects of occurrence probabilities of the different risk events on the transportation model featuring total transportation cost. First, the present research study addresses the problem of identifying and evaluating various risk factors that influence the HazMat transportation network. Next, a modeling framework for HazMat transportation is proposed as a special case of the traditional transportation network in the presence of risk-informed safety constraints that need to be satisfied. A comprehensive characterization of the underlying risk profile that is probabilistically realized through appropriately conducted Monte Carlo simulations that capture the effect of underlying irreducible uncertainties associated with the main risk-drivers is followed by the proposed solution approach to the corresponding minimum cost flow network problem while reducing risks at the desired levels. In order to examine the impact of the occurrence possibilities of different risk events on the transportation model, appropriate parameterized simulation work is carried out, resulting in identifying release probability zones and safe network configurations that correspond to certain low-risk levels and degrees of risk-related uncertainties. These simulation studies help making informed decisions on optimal transportation configurations for ensuring safety in hazardous material shipments. Finally, the presented methodological framework demonstrates its potential usefulness in making risk-informed decisions while transporting goods and classes of materials that can be potentially proven dangerous to public health and ecosystem functions.