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The aim of the present study is the development of a multiscale modeling and optimization framework for hydrogen storage in carbon-based nanoporous adsorbents. The outlined methodology is generic and can be easily adapted to the storage of several gases of relevant importance and/or different physisorbing nanoporous materials. The results indicate clearly how operating constraints (such as temperature limitations arising from safety considerations) can affect the material design in terms of its pore size distribution and how material design constraints (such as those arising from manufacturing limitations) can effect the operation and efficiency of the process. The ultimate objective is to systematically reveal the strong and highly related synergistic benefits between process design/operation decisions and material design aspects so as to ensure an economically attractive, technically feasible, and safe process. © 2006 American Institute of Chemical Engineers AIChE J, 2006

This article presents a procedure for the simultaneous optimization of the design and operation of heat exchangers under milk fouling. This scheme is based on a highly accurate dynamic model described by integral, partial differential, and algebraic equations. Design and operating parameters determined by the dynamic optimization include the length and diameter of the exchanger, the control policy, and the timing of the key operating steps. An economic objective function is used to account for the important factors related to milk heat treatment, and many operating constraints are imposed. Three heat exchanger configurations are considered to study the effect of fouling on the optimal plant design. Optimization indicates that the cost factor due to the interruption of production is dominant, while an increase in energy consumption due to fouling is not very important. The constant wall temperature configuration proved to be the most economical. The economic impact of different control structures was also explored.

A mathematical model for single shell and tube heat exchangers under milk fouling is presented. A fouling model based on a reaction/mass-transfer scheme is detailed in which the main factors during milk heat treatment are quantified in a formal way. This model is coupled with a detailed dynamic model of a shell-and-tube heat exchanger where both radial and axial domains are taken into account. An analytical procedure for the calculation of key parameters provides the means to achieve more accuracy. The simulation results agree well with available experimental work. Four different heat exchanger arrangements are then considered to illustrate their impact on the fouling behavior. The results are encouraging enough to validate current operating industrial techniques for fouling mitigation. For a given thermal duty, short heat exchangers are more prone to fouling due to high-temperature requirements and milk should be heated 11s gradually as possible to minimize fouling. The results show that there are main tradeoffs between design and operation issues.

The effect of axial load on the torsional pile response and the effect of torque on the axial pile response are investigated. To perform this investigation, a computer program was developed which uses the transfer matrix method to analyse a pile supported by a series of coupled axial and torsional elasto-plastic springs. The study indicated that the ultimate torsional and axial pile capacities, as well as the axial displacements and rotations, are significantly affected by the combined load action.