The adsorption of volatile organic compounds (VOCs) on the activated carbon, silica gel, and type-13X synthetic zeolite were investigated by a gravimetric adsorption method. The sorbates (VOCs) include benzene, toluene, o-xylene, p-xylene, and m-xylene. The equilibrium isotherm data obtained from this study were fitted by the Freundlich equation. The standard deviations for the predicted adsorption isotherms in the activated carbon bed were from 0.44 to 0.92, and the standard deviations were from 0.25 to 4.79 in the silica gel bed and were from 0.12 to 0.87 in the 13X zeolite bed.

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 experimental data.

The adsorption of volatile organic compounds (VOCs) on activated carbon, silica gel, and type 13X synthetic zeolite was measured by the method of gravimetric adsorption. The selected VOCs were oxygenated hydrocarbons including methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isopropyl acetate, and isobutyl acetate. The equilibrium isotherm data of this study were fitted by the Freundlich and Langmuir equations. The average values of R 2 when using the Freundlich and Langmuir equations to fit the equilibrium isotherms are 0.99 and 0.96, respectively. The results demonstrate that both the Freundlich and Langmuir equations are adequate for fitting the adsorption data of oxygenated hydrocarbons onto the activated carbon, silica gel, and 13X zeolite.

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To study the interfacial mass transfer phenomena of water vapor absorbed by TEG (triethylene glycol) and DEG (diethylene glycol) solutions, an absorption system was designed and tested in this study. The surface tensions of TEG and DEG solutions were varied by adding a liquid with lower surface tension to observe the interfacial disturbances and the mass transfer performance of the absorption system. In this study, ethanol was added to the absorbent solution. The traditional variable of driving force was replaced by the variable of surface tension times driving force to compare the variation of mass transfer coefficients of systems with and without ethanol added to the absorbent solution. The results showed that surface tension significantly affected the mass transfer performance in the gas-liquid interface. Both mass transfer coefficient and enhancement factors were calculated to analyze the effects of interfacial disturbance on mass transfer performance. The photographs showed that when ethanol was added to the surface of the TEG solution, the interfacial disturbance on the surface of the TEG solution was significant. The experimental results also demonstrated that the mass transfer coefficients were increased due to the addition of ethanol to the absorbent solution. The values of the defined enhancement factor were from 1.047 to 1.143 for the system with DEG solution and from 1.064 to 1.161 for the system with TEG solution. Both driving force and surface tension were important physical properties that affected the mass transfer phenomena of the absorption system. The interfacial disturbance resulting from the addition of ethanol to the absorbent solution can be used to enhance the mass transfer performance for absorption heat pump and absorption air-conditioning systems.