Solar Energy Based Desalination System Using Humidification- Dehumidification Process

Abstract

Solar desalination is one of the most promising techniques used in the production of fresh water for many decades. The technique has evolved with a number of innovations in recent years with which it can compete with water technology market as well. A combination of solar desalination and paddy grass humidifier represents a distinguished technique in solar desalination process. The current research work is aimed at addressing water scarcity problems faced across the globe. This thesis attempts to incorporate Humidification-Dehumidification Desalination Technique (HDHT) using artificial and bio-based packing materials. A detailed thermodynamic analysis was conducted for Paddy Grass Humidification Dehumidification Desalination System (PHDD) in current study through mathematical and experimental methods. In order to produce the maximum amount of fresh water, two configurations were developed and analyzed under weather conditions prevalently observed in the southern states of India. First, the experiments were carried out with artificial packing material (Polypropylene) with and without baffle plates. Next, bio-based packing material (Paddy grass) was used in the second set of configuration with and without baffle plates. The study found that 0.39, 0.46, and 0.73 kg/h of fresh water was produced respectively for without, artificial and bio-based packing materials. The rate of fresh water production got increased to 17% and 46% respectively for artificial and bio-based materials. There was an increase observed in Gain Output Ratio (GOR) as well, in the range of 0.28, 0.40, and 0.65 for without, artificial, and bio-based packing materials. GOR got increased up to 30% and 56% when using artificial and bio-based packing materials respectively. When the inlet temperature of cooling water, to the dehumidifier, was reduced from 40ºC to 20 ºC, it increased the production of distilled water significantly. The performance of PHDD system was evaluated through various physical parameters such as solar collector area, reservoir water tank volume and the temperature of water reservoir. The author conducted cost benefit analysis of the system against other desalination methods. In this analysis, the amount of potable water produced, the amount of energy consumed and iv the cost incurred upon components were compared. The results revealed that irrespective of paddy grass area, the volume of the storage water tank, below and above 40 L, is not considered to be optimal. The cost analysis conducted for the present work proved that the system can function at low maintenance cost in comparison with other similar studies and the price of the yield is approximately 19$/m3. The solar collector area exerts a significant influence upon the augmentation of water yield. The optimal ratio of water reservoir to collector area was 13 L/m3. The present study infers from the experimentation procedure that the bio-based paddy grass packing material is highly advantageous for small-scale fresh water production in remote regions.