Performance and feasibility assessment of an adsorptive-dehumidification system utilizing a heat pipe-based desiccant-coated heat exchanger

Abstract

Dissipating the adsorption heat generated during air dehumidification and providing the desorption heat required for regeneration pose significant challenges in energy-intensive adsorptive air-dehumidification systems. We present an adsorptive-dehumidification system that utilizes a heat pipe–based desiccant-coated heat-exchanger (DCHE) module to overcome the limitations of conventional adsorptive-dehumidification systems. The DCHE-module fabrication involved the synthesis of a composite adsorbent using silica gel, binders (styrene-butadiene rubber and carboxymethyl cellulose), and a graphene solution, followed by an analysis of its physical properties. Although the composite adsorbent exhibited a 21 % lower water–vapor uptake than virgin silica gel, its thermal conductivity was approximately 25 times higher, indicating a notable advantage of the DCHE over a desiccant-packed heat exchanger (DPHE). The performance of the proposed adsorptive-dehumidification system was evaluated in terms of various operating parameters, including the regeneration inlet temperature and cycle time, with emphasis on the moisture removal rate (MRR) and cooling capacity (CC). Under specific conditions, the proposed adsorptive-dehumidification system achieved an MRR of 52.17 g/h and CC of 52.05 W. Sustainable dehumidification and regeneration was achieved by recovering heat from the heat pipes without requiring additional cooling and heating to dissipate the adsorption and desorption heat. Consequently, the maximum coefficient of performance of the system with a single DCHE module under the given operating conditions was approximately 2.60, which can be enhanced by a linear increase in dehumidification capacity with the multi-stage module design. These findings demonstrate a viable approach for developing low-energy, sustainable dehumidification systems that will ultimately contribute to the implementation of net-zero buildings. © 2024 Elsevier Ltd