Design and development of adsorption desalination system

Abstract

Waste heat driven adsorption desalination systems offer great potential in solving the shortage of fresh water. This report presents the design and development of the new two-bed adsorption desalination system as well as the design of the four-bed non-regenerative adsorption desalination system.

The two-bed adsorption desalination system is designed based on the 300-W design capacity. The temperature difference of the hot/cool water inlets and outlets are assumed to maintain at 5℃ at steady state conditions to facilitate the designing of the adsorption system. For the automatic controls of various valves, a logic controller is used. The programming languages of the controller, structured text and ladder logic, are also explained in details. Then, the experimental investigation are discussed. The initial trial runs (200 s, 400 s and 600 s preheating) and its preliminary results show that 600s/1000s cycle time gives the lowest evaporator temperature of 17℃. And the variation of preheating time does not impact on the water production rate.

Finally, the design calculations of the heat exchangers for the four-bed adsorption desalination are shown in details. The designs are based on 12-kW and 8-kW cooling capacities for the two evaporators. Two methods in determining the length of heat exchanger are employed in the design calculations, namely using copper pipe’s heat transfer coefficient and using overall heat transfer coefficient. The various components are then 3D modelled using Solidworks.