Wettability analysis of desiccant beads for HVAC systems

Manfredo Guilizzoni,Stefano De Antonellis

doi:10.1088/1742-6596/1249/1/012005

Manfredo Guilizzoni, Stefano De Antonellis

Open Access

https://doi.org/10.1088/1742-6596/1249/1/012005

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Abstract

Vapour adsorption plays a fundamental role in the operation and performance of innovative heat and mass transfer devices for latent heat recovery in HVAC systems. Materials to be used for such devices should present a high affinity with water vapour; at the same time pores should not be flooded in case the surface finds itself in contact with liquid water (e.g., due to moisture formation) and the surface should minimize the wetted parts. From the latter point of view hydrophobic microporous surfaces would be the most suitable; on the contrary, commonly used materials have hydrophilic and/or macroporous surfaces and their behaviour in presence of moisture is still not fully understood. Therefore, this paper is aimed at studying (mostly experimentally, with the support of numerical simulations) wettability and interaction with water, together with adsorption isotherms, of three commercially available desiccant beads (Silica Gel, Silica Gel impregnated with LiCl, Activated Alumina). Results evidence that the behaviour is significantly different between the three materials, even if their static and dynamic wettability is quite similar.

Highlights

Innovative devices able to effectively transfer both heat and mass between air streams constitute a fundamental tile for high-performance HVAC applications aiming at energy-saving or nearly-zeroemission buildings
Materials to be used for such devices should present a high affinity with water vapour; at the same time pores should not be flooded in case the surface finds itself in contact with liquid water and the surface should minimize the wetted parts
This paper is aimed at studying wettability and interaction with water, together with adsorption isotherms, of three commercially available desiccant beads (Silica Gel, Silica Gel impregnated with LiCl, Activated Alumina)

Summary

Introduction

Innovative devices able to effectively transfer both heat and mass between air streams constitute a fundamental tile for high-performance HVAC applications aiming at energy-saving or nearly-zeroemission buildings. Materials to be used for such devices should present a high affinity with water vapour, while at the same time the surface pores should not be flooded, and the surface should minimize the wetted parts, in case the surface find itself in contact with liquid water (e.g., due to moisture formation). From the latter point of view, hydrophobic microporous surfaces may be the most suitable; but to promote adsorption, commonly used materials have on the contrary hydrophilic and/or macroporous surfaces. Investigation was experimental, with the support of Computational Fluid Dynamics (CFD) in verifying and tuning the used technique

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Conclusion