Moisture relationship with power

Power Consumption. A previous report (2) showed the power consumption of the pellet mill as a function of throughput. Subsequent work has shown there were errors in these measurements and the result is hereby withdrawn. Later work, using processed office waste with added moisture (75% of the samples contained 10 - 30 wt%, 22% of the samples contained 30 - 50 wt%, and the remainder 10 wt%) showed that the relationship between power consumption P(kW), and feedrate to the densifier F (short tons/h, dry wt basis), could be represented by P = 50.5F + 21.7, for 63 determinations, 0.3 < F < 1.7 Mg/h, with a correlation coefficient r = 0.964 and a standard error of the regression line of 5.7. The intercept should be equal to the idling power of the machine which was separately measured as 24 kW. There was no discernible relationship between power consumption and moisture content. 

Li et al. (2010) investigated the microwave-assisted convective drying of apple slices with time-adjusted power in feedback temperature control. Three desirable temperatures of 75, 65, and 55 °C were chosen, and the corresponding maximum power requirements were set at 400, 300, and 240 W, respectively. The relationships of power versus time and of power versus moisture content (d.b.) can be described by the following equations, respectively ... 

Electrical moisture meters provide a quick and reasonably accurate nondestructive alternative. The direct-current resistance of the timber is measured or either the alternating-current capacitance or power loss can be measured. Direct-current resistance moisture meters are more common a pair of needles, a fixed distance apart, is driven into the wood across or along the grain (depending on the manufacturer s instructions) and the electrical resistance measured. The procedure is reasonably accurate between the fibre saturation point (defined later) at 30% and about 6% moisture content (at which point the resistance becomes too great to measure with reasonable accuracy). In this moisture content range, the relationship between electrical resistance and moisture content is represented by a log-log plot. 

The effects of a number of environmental factors on viscoelastic material properties can be represented by a time shift and thus a shift factor. In Chapter 10, a time shift associated with stress nonlinearities, or a time-stress-superposition-principle (TSSP), is discussed in detail both from an analytical and an experimental point of view. A time scale shift associated with moisture (or a time-moisture-superposition-principle) is also discussed briefly in Chapter 10. Further, a time scale shift associated with several environmental variables simultaneously leading to a time scale shift surface is briefly mentioned. Other examples of possible time scale shifts associated with physical and chemical aging are discussed in a later section in this chapter. These cases where the shift factor relationships are known enables the constitutive law to be written similar to Eq. 7.53 with effective times defined as in Eq. 7.54 but with new shift factor functions. This approach is quite powerful and enables long-term predictions of viscoelastic response in changing environments. 

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