Experimental Investigation of A Liquid Desiccant System for Air Dehumidification Working With Ionic Liquids

Zegenhagen, M.T.; Ricart, C; Meyer, Thomas Alexander; Kühn, Roland; Ziegler, Felix

doi:10.1016/j.egypro.2015.02.159

Cited by 31 publications

(18 citation statements)

References 10 publications

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“…Luo et al [ 11 ] presented the feasibility of [Emim]BF 4 as an IL desiccant solution, and in a following study, Luo et al [ 12 ] tested the surface vapour pressures of aqueous solutions of [Bmim]BF 4 and [Dmim]OAc, finally comparing the dehumidification performance of the latter with conventional desiccants. A similar comparison was carried out by Zegenhagen et al [ 13 ], whereas, Varela et al [ 14 ] and Giannetti et al [ 15 ], respectively, studied and modelled the wetting ability of an IL solution at different mass fractions flowing over the aluminium substrate of a newly designed internally cooled/heated contactor.…”

Section: Introductionmentioning

confidence: 88%

Thermodynamic Analysis of Irreversible Desiccant Systems

Giannetti

Yamaguchi

Rocchetti

et al. 2018

Entropy

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A new general thermodynamic mapping of desiccant systems' performance is conducted to estimate the potentiality and determine the proper application field of the technology. This targets certain room conditions and given outdoor temperature and humidity prior to the selection of the specific desiccant material and technical details of the system configuration. This allows the choice of the operative state of the system to be independent from the limitations of the specific design and working fluid. An expression of the entropy balance suitable for describing the operability of a desiccant system at steady state is obtained by applying a control volume approach, defining sensible and latent effectiveness parameters, and assuming ideal gas behaviour of the air-vapour mixture. This formulation, together with mass and energy balances, is used to conduct a general screening of the system performance. The theoretical advantage and limitation of desiccant dehumidification air conditioning, maximum efficiency for given conditions constraints, least irreversible configuration for a given operative target, and characteristics of the system for a target efficiency can be obtained from this thermodynamic mapping. Once the thermo-physical properties and the thermodynamic equilibrium relationship of the liquid desiccant mixture or solid coating material are known, this method can be applied to a specific technical case to select the most appropriate working medium and guide the specific system design to achieve the target performance.Entropy 2018, 20, 595 2 of 13 (i.e., the temperature of the air entering a conditioned room can be relatively high). Low exergetic level heat (60-90 • C) (Tu et al. [3]), rather than electricity, can be used as the main energy source, enabling the use of renewable sources (Jani et al. [4]) and waste heat recovery (Ge et al. [5]). A higher system reliability (Giampieri et al. [6]) can be ascribed to the absence of a compressor. Desiccant-cooling systems employ a sorptive material that undergoes a cycle of thermodynamic transformations by sequentially facing the process air and the regeneration stream, thus realising the necessary heat and mass exchanges. These processes are driven by the characteristic vapour pressure at the desiccant-air interface, which is related to the equilibrium isotherm of the specific desiccant material: a univocal relation between the moisture content, pressure and temperature. During the sorption of moisture, the related heat of sorption is released and transmitted through the material itself, which decreases its sorption capacity. Therefore, heat and mass transfer are coupled processes influenced by the contactor configuration, the thermo-physical properties of the desiccant material, the fluid dynamics of the air streams and the contingent operating conditions. Furthermore, a large variety of desiccant mixtures and coatings are available and more new materials are under development. For an updated literature review about absorptive or adsorptive materials and desiccant ...

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Section: Introductionmentioning

confidence: 88%

Thermodynamic Analysis of Irreversible Desiccant Systems

Giannetti

Yamaguchi

Rocchetti

et al. 2018

Entropy

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“…The Clausius-Clapeyron equation can be used to approximately describe the relationship between the heat of absorption and the temperature-dependent equilibrium vapour pressure of the desiccant solution [91]:…”

Section: Heat Of Absorptionmentioning

confidence: 99%

Thermodynamics and economics of liquid desiccants for heating, ventilation and air-conditioning – An overview

Giampieri

Smallbone

et al. 2018

Applied Energy

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In an effort to minimise electricity consumption and greenhouse gases emissions, the heating, ventilation and airconditioning sector has focused its attention on developing alternative solutions to electricallydriven vapour-compression cooling. Liquid desiccant airconditioning systems represent an energyefficient and more environmentally friendly alternative technology for dehumidification and cooling, particularly in those cases with high latent loads to maintain indoor air quality and comfort conditions. This technology is considered particularly efficient in hot and humid climates. As a matter of fact, the choice of the desiccant solution influences the overall performance of the system. The current paper reviews the working principle of liquid desiccant systems, focusing on the thermodynamic properties of the desiccant solutions and describes an evaluation of the reference thermodynamic properties of different desiccant solutions to identify which thermodynamic, physical, transport property influences the liquid desiccant process and to what extent. The comparison of these thermodynamic properties for the commonly used desiccants is conducted to estimate which fluid could perform most favourably in the system. The economic factors and the effect of different applications and climatic conditions on the system performance are also described. The paper is intended to be the first step in the evaluation of alternative desiccant fluids able to overcome the problems related to the use of the common desiccant solutions, such as crystallization and

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“…The most utilized is the conventional vapor compression air conditioners. Although conventional air conditioners have many advantages, such as their reliability, stability, effective heat transfer rates, and compact sizes, they still have the problem of high overall electricity demand and peak electricity loads [4]. Besides, handling the latent load in vapor compression systems requires cooling the supply air beneath its dew point temperature.…”

Section: Introductionmentioning

confidence: 99%

Adaption of an Evaporative Desert Cooler into a Liquid Desiccant Air Conditioner: Experimental and Numerical Analysis

2019

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Desert coolers have attracted much attention as an alternative to mechanical air conditioning systems, as they are proving to be of lower initial cost and significantly lower operating cost. However, the uncontrolled increase in the moisture content of the supply air is still a great issue for indoor air quality and human thermal comfort concerns. This paper represents an experimental and numerical investigation of a modified desert air cooler into a liquid desiccant air conditioner (LDAC). An experimental setup was established to explore the supply air properties for an adapted commercial desert cooler. Several experiments were performed for air-water and air-desiccant as flow media, at several solutions to air mass ratios. Furthermore, the experimental results were compared with the result of a numerical simplified effectiveness model. The outcomes indicate a sharp reduction in the air humidity ratio by applying the desiccant solutions up to 5.57 g/kg and up to 4.15 g/kg, corresponding to dew point temperatures of 9.5 • C and 12.4 • C for LiCl and CaCl 2 , respectively. Additionally, the experimental and the numerical results concurred having shown the same pattern, with a maximal deviation of about 18% within the experimental uncertainties.

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Experimental Investigation of A Liquid Desiccant System for Air Dehumidification Working With Ionic Liquids

Cited by 31 publications

References 10 publications

Thermodynamic Analysis of Irreversible Desiccant Systems

Thermodynamic Analysis of Irreversible Desiccant Systems

Thermodynamics and economics of liquid desiccants for heating, ventilation and air-conditioning – An overview

Adaption of an Evaporative Desert Cooler into a Liquid Desiccant Air Conditioner: Experimental and Numerical Analysis

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