Scaling criteria

Another way to examine scaleup of hydrodynamics is to build a cold or hot scale model of the commercial design. Validated scaling criteria have been developed and are particularly effec tive for group B and D materials [Gheksmau, Hyre and Woloshuu, Powder Tech., 177-199 (1993)]. 

To test the scaling criteria suggested by Equation (8), we will look at velocity profiles between 10 and 30rpm. Figure 6A shows the scaled velocity profiles [i.e., all data is divided by using V = (g/d) / and the dis-... 

To validate both the particle velocity hypothesis and our scaling criteria, similar experiments were run in a number of different capacity V-blen-ders. Vessel dimensions are shown in Table 2, along with a schematic, shown in Figure 8. 

The SUPAC-IR guidance suggests that a pilot-scale batch be, at minimum, one-tenth that of full production scale or 100,000 dose units (tablets or capsules), whichever is larger. If the dose of drug T was 100 mg, a 10-kg batch will, in theory, produce 100,000 units but will not meet the production-scale criteria. The origin of the production-scale criterion was intended primarily to ensure that the pilot batch was manufactured by a procedure fully representative of and simulating that used for full manufacturing scale (e.g., heat and mass transfer efficiency). 

R. M. Crone, P. R. Peck, M. S. Jhon, and T. E. Karis, Scaling criteria for slider miniaturization using the generalized Reynolds equation, J. Tribol. 115, 566-572 (1993). 

This technology led to testing of a full scale, 100 million lb-per-year ethylene reactor. The full-scale tests have verified scale criteria and gas yield cracking patterns. To further minimize the technical risk and complete the development effort, Union Carbide is constructing a 15 MM ACR prototype unit at Seadrift, TX, primarily to prove long-term equipment operability. This demonstration unit will be completed in 1979 and can lead to the construction of a world-scale ethylene unit by the mid-1980s. 

Thus, the ACR scale criteria has been verified under the extreme condition of directly scaling from a pilot to a full-scale reactor. This allows the smaller scale ACR demonstration unit to be designed with confidence. As required, the data from the demonstration unit will be used to further refine the scaling techniques before the commercial ACR process design is finalized. 

For deformable growth and consolidation where a limit of growth is not achieved, a constant deformation Stokes number Stjef [Eq. (21-118)] should be maintained with scale-up. Depending upon the choice of impact velocity Uq (Table 21-22) and assuming a constant profile of developing yield stress Y, this leads to different scaling criteria as follows ... 

For systems approaching a limiting granule growth with less deformation, constant viscous Stokes number should be maintained. This does not alter the scaling criteria based on the deformation Stokes... 

The more general limitations of ecosystem models center on the interpretation of results. The processes occurring in a microcosm are not on the same time and spatial scales as those in the natural environment. Effects which are artifacts of the microcosm design are not always clearly distinguishable. In engineering models, these scaling effects are accounted for by the application of scaling criteria. Similar criteria need to be established for model ecosystems before environmental exposure predictions can be reliably made (707). 

Questionnaire Seven sensory criteria are chosen to cover the main dimensions of variation within the trials, with of course a focus on the important dimensions for the project. There are four scale criteria, namely acid intensity, sweet intensity, global aroma intensity, orange intensity, and three CATAs, namely off note, fresh aroma and citrus note. Note For aroma note, CATA is often selected as it allows for an easier evaluation with untrained judges. 

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