Fig. 9.7. Effect of scale on the ability to remove the waste metabolic heat by wall cooling in a continuously-mixed, forcefully-aerated bioreactor, of the type shown in Fig. 9.3(a), as calculated by Nagel et al. (2001a). The Y-axis represents the ratio of the maximum wall cooling capacity to the maximum metabolic heat production rate. The calculations are done for three length-to-diameter ratios in a situation in which the maximum O2 uptake rate is 0.0191 mol s-1 m-3 bed, the overall heat transfer coefficient for heat transfer across the wall to the cooling water is 100 W m-2 °C-1 and the temperature difference between the wall and the bed is 20°C. Where the curve is above the dashed horizontal line, wall cooling is sufficient to maintain the bed temperature at the desired value. Conversely, where the curve is below the dashed horizontal line wall cooling is not sufficient to maintain the bed temperature. Adapted from Nagel et al. (2001a) with kind permission from John Wiley & Sons, Inc.
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