Experimental and Theoretical Study of Liquid Desiccant Dehumidification System by Using the Effectiveness Model

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Hassan Pahlavanzadeh ◽  
Parisa Nooriasl
Keyword(s):  
Mass Transfer ◽  
Lithium Chloride ◽  
Packed Bed ◽  
Air Conditioner ◽  
Liquid Desiccant ◽  
Effectiveness Model ◽  
Transfer Unit ◽  
Predicting Performance ◽  
Cooling Air ◽  
Evaporation Cooling

Desiccant evaporation cooling technology is compatible with the environment and can be used as an air conditioner in the indoor environment of the buildings. The characteristics of dehumidification column of the liquid desiccant evaporation cooling air conditioning system (LDCS) are introduced in this paper. This system was designed and manufactured for this purpose. Lithium chloride (LiCl), as liquid desiccant, and a packed bed column were used for the dehumidification. The described system includes a part for processed air simulation in various temperatures, humidities, and flow rates. The effectiveness model, based on heat and mass transfer equations, is considered for predicting performance of the lithium chloride dehumidification system. For validation purpose, a comparison was performed between experimental outlet data of the system and the corresponding results of the experimental model that showed a satisfactory correlation i.e., increase in the mass transfer unit number (NTU) leads to a better performance of the dehumidification system. In addition, factors leading to increase in NTUs are also investigated.

An Analysis of Packed Bed Liquid Desiccant System

2013 ◽  
Vol 390 ◽  
pp. 680-684
Author(s):  
Hesamoddin Salarian
Keyword(s):  
Mass Transfer ◽  
Volume Ratio ◽  
Packed Bed ◽  
Characteristic Parameter ◽  
Flow Rate Ratio ◽  
Liquid Desiccant ◽  
Packed Tower ◽  
Air Conditioning System ◽  
New Type ◽  
Packing Size

In this paper a new type of open absorption the liquid desiccant, air conditioning system will be introduced. The dehumidifier and regenerator play the most important role in this system.For liquid-gas contact, packed towers with low pressure drop provide good heat and mass transfer characteristics for compact designs. Thus, this analysis considers the packed tower liquid desiccant systems. The experimental data have been obtained from a built prototype of liquid desiccant system in a packed bed unit with a surface area per unit volume ratio of 125m2/m3, the liquid desiccant, viz lithium chloride. The result showed that the mean mass transfer coefficient of the packing dehumidifier was 0.02kg/m2s. Also the absorber characteristic parameter, the packing size or number of transfer units (NTU), and air-to-desiccant solution mass flow rate ratio (ASMR) are crucial parameters. These parameters affect humidity and enthalpy effectiveness and will be introduced and defined in this paper.

scholarly journals Experimental Evaluation of Sulfur Dioxide Absorption in Water Using Structured Packing

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Rosa-Hilda Chavez ◽  
Nicolas Flores-Alamo ◽  
Javier de J. Guadarrama
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Nuclear Research ◽  
Packed Bed ◽  
Performance Model ◽  
Two Phase ◽  
Average Deviation ◽  
Absorption Column ◽  
Structured Packing ◽  
Transfer Unit

An experimental study of hydrodynamic and mass transfer processes was carried out in an absorption column of 0.252 m diameter and 3.5 m of packed bed height developed by Mexican National Institute of Nuclear Research (ININby its acronym in Spanish) of stainless steel gauze corrugated sheet packing by means of SO2-air-water systems. The experiments results include pressure drop, flows capacity, liquid hold-up, SO2composition, and global mass transfer coefficient and mass transfer unit height by mass transfer generalized performance model in order to know the relationship between two-phase countercurrent flow and the geometry of packed bed. Experimental results at loading regimen are reported as well as model predictions. The average deviation between the measured values and the predicted values is±5% of 48-data-point absorption test. The development of structured packing has allowed greater efficiency of absorption and lower pressure drop to reduce energy consumption. In practice, the designs of equipment containing structured packings are based on approximations of manufacturer recommendations.

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

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 40 ◽  
Author(s):  
Mustafa Jaradat ◽  
Mohammad Al-Addous ◽  
Aiman Albatayneh
Keyword(s):  
Indoor Air ◽  
Operating Cost ◽  
Dew Point ◽  
Air Conditioner ◽  
Liquid Desiccant ◽  
Human Thermal Comfort ◽  
Effectiveness Model ◽  
Air Cooler ◽  
Maximal Deviation ◽  
Air Conditioning Systems

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 CaCl2, 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.

scholarly journals DESIGN OF A PACKED-BED ABSORPTION COLUMN CONSIDERING FOUR PACKING TYPES AND APPLYING MATLAB

2016 ◽  
Vol 29 (2) ◽  
pp. 83-104 ◽  
Author(s):  
A. Pérez Sánchez ◽  
E. J. Pérez Sánchez ◽  
R. Segura Silva
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Gas Phase ◽  
Phase Transfer ◽  
Packed Bed ◽  
Design Parameters ◽  
Microsoft Excel ◽  
Absorption Column ◽  
Transfer Unit ◽  
Gaseous Stream

In the present work, a packed bed absorption column is designed to recover certain amounts of ethanol contained in a gaseous stream. Four packing types (50-mm metal Hiflow® rings, 50-mm ceramic Pall® rings, 50-mm metal Top Pak® rings and 25-mm metal VSP® rings) are considered in order to select the most appropriate one in terms of column dimensions, pressure drop and mass-transfer results. Several design parameters were determined including column diameter (D), packing height (Z), overall mass-transfer coefficient (Km) and gas pressure drop (P/Z), as well as the overall number of gas-phase transfer units (NtOG), overall height of a gas-phase transfer unit (HtOG) and the effective surface area of packing (ah). The most adequate packing to use for this absorption system constitutes the 25-mm metal VSP® rings, since it provided the greatest values of Km (0.325 kmol/m3.s), and ah (169.57 m-1), as well as the lowest values of both Z (0.6 m) and HtOG (0.145 m), meaning that it will supply the higher mass-transfer conditions with the lowest column dimensions. The influence of both gas mixture (QG) and solvent (mL) feed flowrates on D, Z, Km, P/Z, NtOG and HtOG was also evaluated for the four packing considered. The design methodology was solved using computing software MATLAB® version 7.8.0.347 (R2009a) (Math Works, 2009), and also Microsoft Excel®.D

Experimental Analysis of Air Dehumidification System With Liquid Desiccant

2010 ◽  
Author(s):  
Li Zhang ◽  
Tanaka Chitose ◽  
Eiji Hihara
Keyword(s):  
Mass Transfer ◽  
Lithium Chloride ◽  
Experimental Analysis ◽  
Chloride Solution ◽  
Experimental Results ◽  
Liquid Desiccant ◽  
Transfer Coefficients ◽  
Air Velocity ◽  
Mass Transfer Coefficients ◽  
Lithium Chloride Solution

The performance of an air dehumidification system with lithium chloride solution used as a desiccant was studied experimentally. First, the mass-transfer coefficients were measured for a structured packed dehumidifier/regenerator. It was shown that the overall mass-transfer coefficients varied from 2.5 to 7.8 g/(m2·s) when the air velocity was increased from 0.5 to 1.5 m/s in the dehumidifier and varied from 1.2 to 2.7 g/(m2·s) in the regenerator. Second, experiments on the air dehumidification system were conducted. The experimental results showed that higher humidity in summer and lower humidity in winter resulted in decreased dehumidifying (humidifying) efficiency.

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