Transonic Combustion has a system for preheated supercritical untra high pressure injection. I think they are on to something.
Not so sure about a Rotary Diesel engine. One of the most basic flaws in a Rotary engine (patented in 1925 by the way) is the surface area exposed to combustion heat, as well as sealing the combustion chamber during compression and expansion at various operating temperatures. The piston in cylinder configuration is very hard, if not impossible to beat in that respect.
Persoanlly I have felt, for a decade, that the ancient (WW1 era) Rotary aircraft engine has a place today as a compression ignition diesel, but that is another discussion altogether.
http://www.tscombustion.com/
I know argonne labs is working on a 60% efficient engine, but I doubt if 75% will ever be reached in a reciprocating engine, which is why I like the Rotary, which is NOT a reciprocating engine. Many debates here many years ago, I just feel that with modern technology, elimination of reciprocation is possible. While a Wankel type Rotary eliminates reciprocation there arre still oscillations involved, but sealing and heat loss to combustion chamber walls are, in my opinion, the killer of the Wankel.
regards
Mech