SDCS Regenerator Water Flow Temperature Effect
Figure 6.13 shows the impact of regenerator water flow temperature on regenerator performance. The water flow temperature range investigated was 45-60 °C. This range was selected because it covers a typical temperature output of a SOFC WHR circuit. Figure 6.13a shows that as the inlet water temperature is increased, moisture addition rate increased from 0.2156 g s-1 at 45 °C up to 0.4331 g s-1 at 60 °C. Similarly, the latent (regenerator) effectiveness increased with inlet water temperature, from 32.83 % at 45 °C to 36.52 % at 60 °C.
Over the range investigated, the temperature of the desiccant solution entering the regenerator HMX core was 40-53 °C. An increase in the regenerator water flow temperature means the desiccant solution is raised to a higher temperature. An increase in desiccant solution temperature will result in a higher solution side vapour pressure. At a constant inlet air condition, this will lead to a greater vapour pressure differential between the solution and air, and thus an increase in mass transfer. Figure 6.13b shows that regenerator thermal input increases as the inlet water temperature increases, from 958 W at 45 °C to 1588 W at 60 °C. The difference in water temperature across the regenerator plate heat exchanger (PX 2) increases from 6.7 to 11.38 °C.
During tri-generation system integration, the regenerator water flow temperature will be dependent on the SOFC CHP system itself; the temperature may be
Fig. 6.13 SDCS regenerator performance with water flow temperature variable to some degree through the volumetric flow in the heat recovery circuit. As a result, the other variables investigated in this section will need to be selected appropriately in order to enable balanced operation. Regeneration of the desiccant solution is possible with a hot water inlet temperature as low as 45 °C, demonstrating the potential for tri-generation system integration.