Heat and mass transfer model of cross flow liquid desiccant air dehumidifier/regenerator

Desiccant systems find applications in a very large variety of industrial and daily usage products including the new HVAC installations. An overview of liquid desiccant technology has been presented in this paper along with a compilation of experimental performance data of liquid desiccant dehumidifiers, empirical dehumidification effectiveness and mass transfer correlations in a useful and easy to read tabular format. The latest trends in this area suggest that hybrid systems are of current interest to HVAC industry, not only for high latent load applications but also for improving indoor air quality. The paper presents a comprehensive comparative parametric analysis of packed bed dehumidifiers for three commonly used desiccant materials viz. triethylene glycol, lithium chloride and calcium chloride, using empirical correlations for dehumidification effectiveness from the literature. The analysis reveals significant variations and anomalies in trends between the predictions by various correlations for the same operating conditions, and highlights the need for benchmarking the performance of desiccant dehumidifiers.

Performance analysis of liquid desiccant dehumidification systems

Air dehumidification by triethylene glycol desiccant in a packed column

Heat transfer—A review of 2005 literature

Experimental analysis of mass transfer in adiabatic structured packing dehumidifier/regenerator with liquid desiccant

Spray towers with and without fin coils were compared for their efficiency in air dehumidification using triethylene glycol (TEG) solutions. Experiments were conducted using different air flow rates, liquid flow rates, temperature and air humidities, and aqueous TEG solution concentrations. Theoretically, an absorber with fin coils reduces the temperature of the desiccant solution, which leads to a greater amount of water vapor removal from the air. It was evident that the performance of the spray tower with fin coils was better than that of the spray tower without fin coils under similar operating conditions. Mass-transfer correlations were developed for both systems, which considered the changes in gas−liquid flow ratio, temperature, TEG concentration, and some physical properties. A dimensional analysis of the process variables was carried out using the Buckingham Pi method to obtain the dimensionless groups of the correlations. Most of the values predicted by the correlations were within ±10% of the e...

Comparison between Spray Towers with and without Fin Coils for Air Dehumidification Using Triethylene Glycol Solutions and Development of the Mass-Transfer Correlations

The process of absorbing water vapor into triethylene glycol (TEG) solutions is achieved in two steps. In the first step, water vapor is condensed into water droplets on the gas−liquid interface. The second step involves the dissolution of water droplets into the TEG solution as a result of the change in surface tension in the surface thin film. This study is focused on the effects of the surface tension gradient on mass transfer performance of the absorption process. An investigation of the disturbance induced by the surface tension gradient and an evaluation of the mass transfer behavior were conducted. As noted, the phenomenon of fluid flow in the surface thin film due to the surface tension gradient is termed the Marangoni effect, and the induced convection is usually termed Marangoni convection. To discuss the relationship between the Marangoni effect and the mass transfer performance, the surface tension of the liquid desiccant was measured under different temperatures and concentrations during expe...

Effects of Marangoni Convection on the Mass Transfer Performance in a Packed-Bed Absorber

A spray tower was used to strip the water vapor from the dilute solutions in this study. The role of each operating parameter and its relationship in this stripping/regeneration (ST/RE) process are still unknown. To improve the ST/RE process and elucidate the relationship between the process variables, an experimental design methodology was used to evaluate the process variables of the ST/RE process. A second-order polynomial model with a multiple linear regression to estimate the model coefficients of the five selected factors (process variables) was proposed to study the influence of the factors on the mass transfer coefficient response in the ST/RE process. Only 32 (or 25) experimental runs were necessary to assess these variables and the model satisfied the process very well since the coefficient of determination (R2) was very close to one. The analysis of the mass transfer performance with these experimental data was also reported in this study.

Honda Wu

Papers

Comparison between Spray Towers with and without Fin Coils for Air Dehumidification Using Triethylene Glycol Solutions and Development of the Mass-Transfer Correlations

Effects of Marangoni Convection on the Mass Transfer Performance in a Packed-Bed Absorber

Evaluation of process variables in a stripping/regeneration process using the experimental design methodology