Reconcentration of Aqueous Solutions in a Packed Bed: A Simple Approach

Introduction In recent years attempts have been made to use packed beds in open-cycle liquid desiccant cooling systems for the dehumidification process and/or for regenerating weak aqueous solutions. The possibility of reconcentrating the aqueous solution in a packed bed by means of solar-heated air was investigated by Leboeuf and Lof [1] and Factor and Grossman [2]. The schematic of the reconcentration process is shown in A step-wise heat and mass balance across the bed is used to determine the performance of the reconcentration process. However, due to the abundance of variables involved with the packed bed, the analysis becomes increasingly complex. To reduce the high computational cost, an air moisture removal effectiveness for the dehumidification process was defined (see reference In this paper dimensionless vapor pressure and temperature difference ratios suitable for application in the reconcentration of aqueous solutions are defined. Further, a closed-form analytical solution is obtained to predict the mass of water evaporated from the weak absorbent solution, through a simplified vapor pressure correlation and the dimensionless vapor pressure and temperature difference ratios

THE USE OF AN OPEN CYCLE ABSORPTION SYSTEM IN AUTOMOBILES AS AN ALTERNATIVE TO CFCS

Increased awareness of the impact of chlorofluorocarbons (CFCs) on the global environment has become the impetus in searching for alternative refrigerants and cooling methods for automotive air conditioning. Automotive air conditioning is one industry that heavily uses CFC compounds, and the leakage of CFCs from such air conditioners is substantial compared to that from stationary air conditioners. Therefore, the use of non-CFC air conditioners in automobiles is apparently becoming very important. The main objective of this paper is to study the feasibility and design of an air conditioning system for automobiles using the Open Cycle Absorption System, with LiBr-H2O as the working fluid. Also, some suggestions are given to minimize the power loss like making use of the exhaust gas to pre-heat the weak desiccant. Evaluating the COP, of the designed air conditioning system for buses is the main scope, and it is found that the COP of the system is increasing with the increase in regeneration temperature at fixed evaporator and absorber temperatures. The system components are plotted in a schematic and flow chart as well as psychometric chart showing the complete process of conditioning and dehumidifying air

Anthraquinone pigments of Barleria buxifolia Linn

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EXPERIMENTAL STUDY OF HYBRID LIQUID DESICCANT BASED VAPOR COMPRESSION COOLING SYSTEM

In the kingdom of Saudi Arabia, a vast amount of energy is used for air-conditioning and this paper describes a new approach to air conditioning. In the proposed hybrid cooling system, liquid desiccant is used to remove the latent load and the conventional vapor-compression system is used to provide sensible cooling only. In this experimental study, calcium chloride solution is used as the desiccant to dehumidify the air. Gauze-type structured packing towers are used for the dehumidification of air and also for regeneration of the weak desiccant. The designed packed bed dehumidifier and the regenerator are combined with a 5-ton capacity vapor compression system along with the heat recovery units. This paper presents results from a detailed experimental investigation of the heat and mass transfer in a structured packing dehumidifier and regenerator under a variety of operating conditions. In the present study, for the sake of comparison between hybrid and conventional cooling systems, the COP for the cooling system is defined as the heat removed from the space to be cooled divided by energy input for the cooling system. Three different modes of regeneration are considered for the hybrid cooling system and the COP values are compared with conventional vapor compression system. Results show that the ratio of the outlet-to-inlet absolute humidity reaches a steady state value of about 0.6 and the temperature of air decreased from 48 to 38o C in the dehumidifier of the hybrid system. Moreover, it is found that hybrid cooling system provides higher COP compared with conventional system