Numerical modeling of adsorption desalination and investigation evaporator pipe lenght effect on desalinated water

Adsorption desalination system employs low temperature waste heat, which is available in renewable energy sources. A three-dimensional transient model has been developed for modeling heat and mass transfer in adsorbent bed silicagel/water pair and validated by the experimental results. Evaporator is one of the main adsorption desalination parts and in this study, the effects of shell and tube evaporator pipe lenght on the performance ratio (PR) and specific daily water production (SDWP) are numerically investigated. According to modeling results, it was found that the performance ratio increases by increasing the evaporator pipe length, while aproaching 0.66. SDWP has an optimum cycle time for each evaporator pipe length, which increases with increasing the evaporator size. However, it was also found that the SDWP remains almost constant for evaporator pipe length larger than 4m. Specific daily water production increases by 11% for the pipe length increase from 2m to 4m, while it only increases by 6% when the pipe lenght increases from 4m to 8m.