Preliminarily Study of Extracting Water from Air Utilizing Ship's Waste Heat from Cylinder Jacket Cooling Water

Feasibility of extracting water from air on ship's environment was evaluated on a general cargo ship navigating between Dalian and Hamburg at May. Firstly, analysis of the energy equilibrium among the heat evaluated from fuel consumption rate and that distributed to different parts of the main engine system was carried out, an experimental unit employing the waste heat of the cylinder jacket water was then set up on the afterdeck nearby central air conditioning room. Two adsorption towers with the same size and capacity were design in consideration of the heat and mass transfer characteristic of the water vapor within the adsorbent bed of the silica gel and that of the composite compounded with calcium chlorate. Daily amount of water produced from the extracting unit and that from desalination plant were compared in terms of the main indices prescribed by the National Standard for Drinking Water. Results show that the waste heat of the cylinder jacket cooling water under normal working condition is enough to meet the need of the heat powering the extracting unit, silica gel with pores larger than mesopore is a better adsorbent in marine environment, the composite has a better performance in water vapor adsorption, but performance in both silica gel and the composite will be weakened on board. Results also reveals that the indices of water from the extracting unit and the desalination plant are all within the permissible range prescribed by the national standard. Conclusions are drawn that the monolith of the adsorbent and the flexible connection should be used to dampen the influence from the vibration and bumping of the ship.