Carpet plot

Finally, carpet plots of efficiency against specific work are shown in Fig. 3.16, for all these plants. The increase in efficiency due to the introduction of heat exchange, coupled with reheating and intercooling, is clear. Further the substantial increases in specific work associated with reheating and intercooling are also evident. 

The (arbitrary) overall efficiency and specific work quantities obtained from these calculations are illustrated as carpet plots in Fig. 4.11. It is seen that the specific work is reduced by the turbine cooling, which leads to a drop in the rotor inlet temperature and the turbine work output. Again this conclusion is consistent with the preliminary analysis and calculations made earlier in this chapter. 

Fig. 5.4 shows a carpet plot of overall efficiency against specific work for the cooled [CBTJici plant (single step) with pre.ssure ratio and combustion temperature as parameters. As shown earlier, by the preliminary air standard analysis and the subsequent calculations in Chapter 4, there are relatively minor changes of thermal efficiency compared with the uncooled plant [CBT]iuc, but there is a major effect in the reduction of specific work. 

Fig. 3.16 showed carpet plots of efficiency and specific work for several dry cycles, including the recuperative [CBTX] cycle, the intercooled [CICBTX] cycle, the reheated [CBTBTX] cycle and the intercooled reheated [CICBTBTX] cycle. These are replotted in Fig. 6.17. The ratio of maximum to minimum temperature is 5 1 (i.e. T nx 1500 K) the polytropic efficiencies are 0.90 (compressor), 0.88 (turbine) the recuperator effectiveness is 0.75. The fuel assumed was methane and real gas effects were included, but no allowance was made for turbine cooling.

Macchi et al. provided a similar comprehensive study of the more complex RWI cycles as illustrated in Fig. 6.19, which shows similar carpet plots of thermal efficiency against specific work for maximum temperatures of 1250 and 1500°C, for surface intercoolers. The division of pressure ratio between LP and HP compressors is again optimised within these calculations, leading to an LP pressure ratio less than that in the HP. For the RWI cycle at 1250°C the optimisation appears to lead to a higher optimum overall pressure ratio (about 20) than that obtained by Horlock [5], who assumed LP and HP pressure ratios to be same in his study of the simplest RWI (EGT) cycle. His estimate of optimum pressure ratio... 

FIGURE 40.24 High-temperature drying (140°C/85°C). Carpet plot after 5 h of drying. Internal overpressure, resaturation of the end piece, thermal conduction along the thickness, and end piece close to the wet-hulh temperature are evident on these plots. Note the high value of internal pressure and the absence of end-piece resaturation obtained for heartwood (b). 

Resilience of textile fabrics when compressed in the bent state is related to wrinkle resistance and retention of shape, drape, and hand. Resilience is an important parameter for evaluating blankets, wearing apparel in which warmth is a factor, pUe fabrics including carpets, and bulk fiber utilization in mattresses, cushions, etc. The general method for determining compressional resilience is to compress and unload the material cycHcahy, creating a plot of compressive force versus fabric thickness. 

Fig, 14.12 Visible staining, indicated by CIELAB A values, plotted on logarithmic scales versus the FD C Red 40 content of the initially blue cut pile carpet (BCP), blue level loop carpet (BLL), and white level loop carpet (WLL). White standard plate as the reference (target). (Reproduced with permission from Ref. 90. Copyright 1995 by AATCC). 

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