Development of a new type of seal system for use in ocean current or tidal power generation

Ocean current or tidal power is a promising renewable resource. For the generation of electricity from them, it is important to construct waterproof system with reducing mechanical energy loss. However, there is no appropriate sealing system that is completely waterproof and low friction. So, we developed a new type of seal system for using in ocean current and tidal power generation. We introduced seal lips made of a polyvinyl formal (PVF). PVF lips were attached to a rotating shaft, and a non-Newtonian, aqueous solution of 3.0wt% polyethylene glycol (PEG) with a molecular weight of 2.0 million was applied as lubrication. This sealing system was low water leakage, less than 0.05ml/h, was recorded throughout the experiment. Mean frictional torque was lower than those with a mechanical seal or an oil seal, both of which are generally used for industrial components. Furthermore, frictional torque was stable, and friction was independent of the speed of the rotating shaft.