Simulation of the Solar Powered Humidification-Dehumidification Distillation Unit Performance Working Under Iraqi Conditions Using TRNSYS

Abstract

The problem of drinking water scarcity represents a significant threat for Middle East countries particularly in the desert regions of Iraq. Thus, there is still a need to study and investigate the techniques and methods of water desalination to be available for fresh water supply. Simulation model of the distillation unit based on the humidification – dehumidification processes (HDH) was developed using TRNSYS 16 software. A yearly performance of the HDH unit was done based on step of one hour under the conditions of Baghdad, Iraq, 33.3 ° N latitude, 44.14° N longitude and elevation of 34 m. Meteonorm V7.3 software was used to obtain the weather data for Baghdad city. The key variable of this work is the variation of the salty water flow rate through the parabolic trough collector. The effect of salty water flow rate on the fresh water productivity, properties of the air entering and leaving the humidifier and dehumidifier in addition to the temperature of the water leaving the collector were studied. The salty water flow rate considered in this study was 50, 55, 60 and 75 lit/hr. All the input variables have been studied experimentally in earlier work. The results showed that, increasing the water flow rate through the collector improves the HDH unit performance, the water production increases insignificantly when the water flow rate increases more than 60 lit/hr. The best volume flow rate of water through the collector around the year was 60 lit/hr, that gives a yearly productivity of fresh water 17650 lit/year which is equal to about 2011 lit/m2.year. At a given salty water flow rate, the maximum productivity of fresh water is in conjugated with the lowest outer relative humidity.