Performance Investigation of a Hollow Fiber Membrane-Based Desiccant Liquid Air Dehumidification System

Sebastian Englart,Krzysztof Rajski

doi:10.3390/en14113320

Sebastian Englart, Krzysztof Rajski

Open Access

https://doi.org/10.3390/en14113320

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Abstract

The membrane-based desiccant liquid air dehumidification system is a promising technology for efficient humidity control in buildings. The use of a membrane module allows, among other things, for a compact design with a relatively large heat and mass transfer area and eliminates carryover of solution droplets. In this paper, a cross-flow, hollow-fiber membrane module was proposed for air dehumidification and regeneration of lithium chloride. A two-dimensional heat and mass transfer model for cross-flow in a membrane module used for air dehumidification and liquid desiccant regeneration was developed. The effectiveness, moisture removal rate and moisture removal rate were studied numerically and validated against experimental results. Based on the numerical simulations, the most favorable ranges of operating conditions were determined. It was found that the operating conditions significantly impact the dehumidification performance. The proposed dehumidifier maintains its performance in a wide range of inlet air humidity ratios. For dehumidification, the recommended temperature of the incoming solution was in the range of 14–18 °C, while for regeneration the solution range was 40–50 °C. The packing fraction was suggested in the range of 0.30–0.40. These results can help design membrane-based liquid dehumidification systems.

Highlights

The appropriate relative humidity in buildings affects comfort conditions, prevents the growth of mold and may help to limit the survival of viruses, including SARS-CoV2 [1]
The mass transfer rate of absorbed water vapor depends on the difference in its partial pressures in the boundary condition above the solution and moist air
A a parametric study was carried out to investigate the effects of various operating conparametric study was carried out to investigate the effects of various operating conditions

Summary

Introduction

The appropriate relative humidity in buildings affects comfort conditions, prevents the growth of mold and may help to limit the survival of viruses, including SARS-CoV2 [1]. Due to significant electricity consumption in traditional air-conditioning systems, the need for novel solutions for maintaining thermal comfort in indoor environments is increasing [2]. The use of liquid desiccants can be one of the alternative solutions for air dehumidification. Liquid desiccants are fluids characterized by their ability to absorb water vapor from moist air. The mass transfer rate of absorbed water vapor depends on the difference in its partial pressures in the boundary condition above the solution and moist air. Inorganic aqueous salt solutions such as calcium chloride (CaCl2 ), lithium chloride (LiCl), lithium bromide (LiBr) and magnesium chloride (MgCl2 ) can be used as liquid desiccants [3,4,5]. The solution LiCl at a given temperature and concentration has the lowest partial pressure value and the lowest equilibrium moisture content

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