The experimental investigation on the performance of a low temperature waste heat-driven multi-bed desiccant dehumidifier (MBDD) and minimization of entropy generation

We present the experimental investigation on the performance of multi-bed desiccant dehumidification system (MBDD) using a thermodynamic framework with an entropy generation analysis. The cyclic steady state performance of adsorption–desorption processes at the assorted heat source temperatures, and typical ambient humidity conditions was carried out. MBDD unit uses type-RD silica gel pore surface area with of 720 m2/g. It has a nominal diameter range of 0.4 to 0. 7 mm. The key advantages of MBDD are: (i) it has no moving parts rendering less maintenance, (ii) energy-efficient means of dehumidification by adsorption process with low temperature heat source as compared to the conventional methods, (iii) although it is a pecked bed desiccant, a laminar chamber is employed by arranging the V-shaped configuration of heat exchangers and (iv) it is environmental friendly with the low-carbon footprint. Entropy generation analysis was performed at the assorted heat source temperatures to investigate the performance of MBDD. By conducting the entropy minimization, it is now able to locate the optimal operating conditions of the system while the specific entropy generation is found to be minimal. This analysis shows that the minimization of entropy generation in the dehumidification cycle leads to the maximization of COP in the MBDD and thus, higher delivery of useful effects at the same input resources.

► Developed the numerical model to capture the transient behaviour of desiccant dehumidification system.
► Gibbs’ free energy approach is applied to capture the component entropy generation.
► Specific entropy generation is introduced to locate the minimum entropy generation point.
► The numerical model agrees well with the experimental results within 5–10%.