Multi-scale design

Lee, S.F., Hong, C.W. Multi-scale design simulation of a novel intermediate-temperature micro solid oxide fuel cell stack system. Int. J. Hydrogen Energy 2010, 35,1330-8. 

For all of these reasons, the structured multi-scale chemical devices envisioned here offer the perspective of significant innovation through the use of microfabrication in the chemical process industries. To illustrate these possibilities, the following sections demonstrate how multi-scale structuring can provide a new degree of freedom for process intensification/miniaturization and contribute to the satisfaction of criteria for sustainability. In conclusion, a critical comparison of scale-up, numbering-up and multi-scale design is proposed. 

Multi-scale Design that Reconciles Intensification with Sustainability... 

Multi-scale design, by providing an additional degree of freedom, can open up new paths to true sustainability. In the case examined here, analysis of friction losses in tubular reactors provides a solution capable of intensifying heat-transfer performance without additional energy dissipation. The multi-scale design solution consists of subdividing the main reactant flow in order to apply the intensified conditions to each sub-flow in the system. 

The ratio of specific mechanical energy describes the gain in sustainability. A value lower than unity indicates that the multi-scale design (subscript 2) requires less energy. 

These values confirm what has been observed previously in a single tubular reactor using Ni = N2 and Vi = V2 demonstrates that heat-transfer acceleration (ti > 2) implies an increase in the required specific energy (E2>Ei). This effect is still observed with multi-scale reactors, since the exponent c is always positive. Nevertheless, this increase can be counter-balanced by adapting the multi-scale design with an appropriate value of the ratio of channel numbers. 

In conclusion, despite the simplicity of the sustainability criterion retained, the analysis shows how multi-scale design enables various aspects of process miniaturization and intensification to be reconciled. By including a new design parameter, this strategy makes it possible to reconcile the rapid transfer characteristics offered by... 

Structured Multi-scale Design a New Hybrid Approach... 

Structured multi-scale design methodology should be developed in such as way as to permit reliable qualitative and quantitative techno-economic evaluation of structured multi-scale process systems for both existing and potential production processes. 

---