Mathematical modelling and simulation of the dehumidifier for the tropical region of Malaysia
In this paper, mathematical model for an adiabatic dehumidifier of liquid desiccant air conditioning system is presented. Regression approach is used to generate the mathematical relation between enthalpy and humidity ratio. Flow-pattern between air & desiccant mainly affects the performance of adiabatic dehumidifier therefore to get proper dehumidification counter-flow configuration is considered as previous studies show that counter-flow direction of air to desiccant has better dehumidification results. For validation, results of present study were compared with those of numerical and analytical results of previous studies, and the agreement was found to be quite satisfactory. The developed mathematical model is then used to study the performance analyses of adiabatic-dehumidifier for the tropical region of Malaysia. Analyses are made for the week having very high range of humidity ratio (18 - 19.5 g/kg). The main concern of the current article is given on moisture removal from the ambient air according to thermal comfort-zone.
Experimental analysis of dehumidification performance of counter and cross-flow liquid desiccant dehumidifiers
Abstract In a liquid desiccant dehumidifier, the air-to-solution flow direction plays an important role in the dehumidification performance and the physical size of the dehumidifier tower. In this research, the dehumidification performance of counter-flow and cross-flow liquid desiccant dehumidifiers were compared via a series of experiments carried out in the environmental test chamber. To predict the dehumidification performance of both flow type dehumidifiers in various operating conditions, empirical models returning the dehumidification effectiveness and the enthalpy effectiveness, which were adopted as performance indices, were also derived based on the experimental data. From the sensitivity analysis conducted by using the proposed empirical correlations, it was observed that when the inlet air humidity ratio increased from 10.1 g/kg to 22.7 g/kg, the dehumidification effectiveness and enthalpy effectiveness of the counter-flow liquid desiccant dehumidifier increased from 51.2% to 82.4% and 40.2% to 72.5%, respectively. Meanwhile, both effectiveness values of the cross-flow dehumidifier increased from 62.3% to 63.4% and 46.3% to 55.0%, respectively. Likewise, when inlet solution temperature varied from 15.2 to 31.1 °C, the dehumidification effectiveness and enthalpy effectiveness of the counter-flow type dehumidifier decreased from 71.7 to 45.4% and 64.4 to 47.3%, respectively, while those of a cross-flow type dehumidifier decreased from 65.3 to 54.8% and 55.8 to 45.2%. Consequently, one may conclude that the cross-flow liquid desiccant dehumidifier would provide relatively stable dehumidification performance regardless of the changes in operating parameter, but the cross-flow dehumidifier may have limited dehumidification performance, especially at the lower desiccant solution temperature and in highly humid process air conditions.
Thermodynamic properties of aqueous electrolyte solutions. 1. Vapor pressure of aqueous solutions of lithium chloride, lithium bromide, and lithium iodide
The vapor pressures of aqueous solutions of lithium halides were measured at different concentrations and temperatures from 303.15 to 343.15 K with use of a differential static method. Osmotic and activity coefficients were calculated and compared