SDCS Regenerator Volumetric Air Flow Effect
Figure 6.11 presents the effect volumetric air flow has on regenerator performance. The volumetric air flow range studied is 102-256 m3 h-1. Figure 6.11a shows
Fig. 6.11 SDCS regenerator performance with inlet air volumetric flow as the inlet volumetric air flow increases, the moisture addition rate increases slightly from 0.2299 g s-1 at 102 m3 h-1 to 0.3442 g s-1 at 256 m3 h-1. However, Fig. 6.11a shows that as the inlet air volumetric flow increases, the latent (regenerator) effectiveness decreases. This is because latent effectiveness is calculated with respect to the absolute humidity difference of the regenerator airstream. As the volumetric air flow is increased the absolute humidity difference (increase) of the regenerator airstream actually reduces, and thus the latent effectiveness is reduced. Figure 6.11b shows that as the air volumetric flow increases, the regenerator thermal input also increases from 980.6 to 1294 W. The temperature difference of the heating water flowing through the regenerator plate heat exchanger (PX2) ranges from 7 to 9 °C.
The regeneration process is used to re-concentrate the desiccant solution, and thus allow continuous operation of the dehumidifier. Therefore the regenerator outlet air condition is not of importance, however the moisture removed from the desiccant solution is. As a result, the regenerator should be operated at the highest volumetric air flow, to facilitate increased regeneration. However, during tri-generation system integration, this will need to be balanced with the available thermal input from the SOFC CHP system.