Stove Chimney with Inbuilt Air Inlet

cruizer101

I am wondering is this a thing I've tried looking into it a bit but can't seem to find anything.
I've attached two images to show what I am talking about, an annular chimney which draws air in to feed the stove, these two come from journal papers, I can't find anything from manufacturers/installers.

As I understand having an external inlet is very advantageous as the stove doesn't draw the warm air from the room in thus needing it to be replaced with cold air.
Also preheating intake air improves efficiency, this is often done in industrial settings in someway, capture waste heat to preheat.
This seems like a relatively simple solution to get fresh inlet air without needing to lay other ducting.
Does anyone know of anyone who offers this as an option.
Or is there some reason it isn't offered as an option.

upupup

This is an easy and cheap setup to do yourself, as I have this and I got it accidentally but I don't use it as my stove doesn't have an air intake.
When I put in a flexi flue there was very little room to fill around it with vermiculite so I left it out as it is not essential anyway.There was a gap in the brickwork in the room with the stove into the chimney around the flue which I left open due to laziness:).This gap opens into the chimney so fresh air can be drawn in from outside by pulling it down the chimney on the outside of the flexi flue.
I realized this air could also be contaminated with CO so I blocked the hole but that air would be fine for a stove air intake.