Dehumidifier Desiccant Solution Mass Concentration Effect

Figure 3.19 presents the effect varying the inlet desiccant solution mass concentration from 0.5 to 0.85 has on the performance of the dehumidifier. Figure 3.19a demonstrates a greater air absolute humidity difference and cooling output with increasing desiccant solution mass concentration. At a constant solution temperature an increase in desiccant solution mass concentration results in a lower solution vapour pressure, as shown in Fig. 3.3. Therefore, at a constant inlet air condition the vapour pressure difference between the inlet air and desiccant increases, and thus the mass transfer potential is enhanced. Figure 3.19b demonstrates that increasing the desiccant solution mass concentration from 0.5 to 0.85 increases both the latent and enthalpy effectiveness from 24.63 and 28.85 to 64.1 and 64.39 % respectively.

Section 3.5.1 has presented a parametric analysis investigating the effect: inlet air relative humidity, inlet air temperature, inlet air velocity, desiccant solution mass flow rate and desiccant solution mass concentration have on the performance of the dehumidifier membrane heat and mass exchanger. Based on the set boundary conditions, the desiccant dehumidifier can supply air at a suitable condition for air conditioning applications. The inclusion of a subsequent indirect evaporative cooling device could be considered for further sensible cooling of the air. Working at a wet bulb effectiveness of 78 % (Jradi and Riffat 2014b), a supply air temperature of 19.74 °C could be achieved. Next, Sect. 3.5.2 presents a regenerator parametric analysis.

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