I was also wondering about this claimed lack of oil from a different perspective.
Based on the article, the video embedded within it, and the Technology section of Aquarius' website, this is a double-acting uniflow two-stroke internal combustion engine. As it is double-acting, there is combustion on both sides of the piston, so I am wondering how the piston is cooled, especially given the high power density of this device.
In conventional IC piston engines, the piston is either cooled by the oil [1], or, in the case of small two strokes having a total-loss lubrication system (the sort that the parent post is concerned with) piston cooling is aided by the flow of the incoming mixture through the crankcase. Neither method seems to be feasible here. Has there been a breakthrough in materials (ceramics, perhaps?) which allow for a piston to work at high temperatures?
One other point that just occurred to me is that if you are using a total-loss, combustible lubricant design (which is what conventional gasoline two-strokes do), then the efficiency calculation must include the energy input of the lubricant as well as the gasoline (or whatever is being used purely as a fuel), as the lubricant is also a fuel.
This looks like video jacking. The description talks about acquarius, but the video is about a completely different free piston system being developed by a research group at newcastle university.
That appears to be an earlier iteration, as (one of) the videos embedded in the article does show it to be double-acting, as does the one in the Technology section of the website [1], where it can be seen at 00:34 and 00:42.
Based on the article, the video embedded within it, and the Technology section of Aquarius' website, this is a double-acting uniflow two-stroke internal combustion engine. As it is double-acting, there is combustion on both sides of the piston, so I am wondering how the piston is cooled, especially given the high power density of this device.
In conventional IC piston engines, the piston is either cooled by the oil [1], or, in the case of small two strokes having a total-loss lubrication system (the sort that the parent post is concerned with) piston cooling is aided by the flow of the incoming mixture through the crankcase. Neither method seems to be feasible here. Has there been a breakthrough in materials (ceramics, perhaps?) which allow for a piston to work at high temperatures?
One other point that just occurred to me is that if you are using a total-loss, combustible lubricant design (which is what conventional gasoline two-strokes do), then the efficiency calculation must include the energy input of the lubricant as well as the gasoline (or whatever is being used purely as a fuel), as the lubricant is also a fuel.
[1] https://dieselnet.com/tech/combustion_piston-cool.php