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Show The other clear characteristics of the two curve sets is the marked difference in firing rate between the oil and slurry/gas combination over the experimental range of measurements. By contrast, the idle firing rates (H^ ) and maximum outputs (H ) are similar in value, so the dis-f s placement of the curve sets from each other is due mainly to the differences in the intrinsic efficiency factors, a . The effect of the differences in firing rate is particularly evident in the efficiency curves (Sec. 4.5). The other notable factor, to the extent that it can be examined, is the absence of any effect of slurry type. Slurry //3 was used mainly in the lower data points on the firing curves, but the trends are quite consistent with the points for slurry //2 at the same excess air levels. 4.5 Thermal Efficiency. Figures 9 and 10 illustrate the variation of thermal efficiency with output; the curves are drawn using the relation n - H / H, s f with H calculated from Eq. 1 using the coefficients listed in Table 4. The nature of the efficiency plot is to accentuate the scatter compared with the firing curves, but the trends and comparisons are still clear. The most obvious point is the significantly greater thermal efficiency of the oil (Fig. 10) compared with the slurry/gas (Fig. 9). This is, as previously noted, is quite unexpected and is contrary to expei tat Lons and previous results (14). The point is discussed further below. The curves otherwise show the characteristic expected trends due to the variation of output and excess air, with the efficiency peaking in an assymmetrical curve and with efficiency decreasing with increasing excess air. |