DEVELOPMENT OF A HUMIDIFICATION DEHUMIDIFICATION (HDH) DESALINATION SYSTEM

Abstract

Fresh water is one of most precious resources on earth. At present the world is facing a crisis of fresh drinking water. Over the years many different desalination techniques have be proposed to help overcome this problem. In the recent years, bubble column humidification and dehumidification devices have been suggested as a means of effective desalination. A detailed review of the available literature was performed. Based on the literature review this work proposes a novel bubble column HDH system consisting of a stepped multistage bubble column dehumidifier and a stepped multistage bubble column humidifier, with PCM incorporation. An experimental model of this design was developed. The developed prototype was found to have a productivity of 12.44 litre/m2day. Further, a mathematical model to estimate performance of a simple bubble column HDH system was developed in MATLAB using the Effectiveness–NTU approach. The effect of varying different operating parameters on overall performance was studied in detail using this model. A brief CFD analysis on the basic bubbling phenomena was also conducted using COMSOL MULTIPHYSICS. Finally, a brief cost analysis for the system is presented. Based on the findings of this work, it is concluded that bubble column HDH systems provide a cheap and sustainable solution for the existing water crisis with decent performance. This technology may be applied at the industrial level to help countries like Pakistan survive the impending water shortage especially in areas such as Karachi and Gwadar. For future study this works proposes that these systems be used in combination with a desiccant system or as a moist air supply system for green houses, in addition to providing fresh water.