Steam propulsion set to make a comeback

A new steam-based system that has applications in both pumping and marine propulsion is moving towards commercialisation. Described as a new kind of underwater jet engine, PDX Technology is cheap to manufacture, extremely robust, contains no moving parts and is virtually impossible to block.

Invented by Australian engineer Alan Burns before development in the UK by Pursuit Dynamics, the system uses a continuous steam feed to accelerate a jet of water providing thrust or, in the case of a pump, fluid transfer.

The use of steam propulsion technology in marine craft like speedboats is not only cheaper, but cleaner and more efficient than conventional engines and outboards.

Pursuit Dynamics also sees immediate applications for PDX technology in industrial pumping and marine propulsion, with the ability pump, macerate, aerate, heat or agitate in one unit providing enormous potential in the wastewater, pulp, and other process industries

The PDX system harnesses both the steam expansion, and the subsequent condensation implosion of the steam are used to impart momentum transfer.

Steam is injected into the water within the jet unit to create a region containing steam and water droplets moving at supersonic speeds. The steam condenses, creating an instantaneous pressure drop and subsequent shockwave as the velocity returns to the overall flow rate. Controlled air drawn into the unit by the low-pressure zone can enhance the process, increasing the efficiency of the energy transfer.

In pumping applications the highly energetic flow in the shockwave zone can macerate any fluid-based soft objects passing through it.