Damn those cheese eating surrender monkeys ;-)

Since the energy ouput of an average ICE installed in a vehicle represents only about 18.2% of the energy of the fuel (gas) used, it would be logical to improve the current ICE efficiency 2 or 3 folds by reducing the 62.4% of the energy currently lost as close to zero as possible.

Only about 12.6% of the input energy goes to the wheels.

1) stop and start could reduce most of the 17.2 % energy losses in idling.

2) Turbo chargers + VVT + DFI + ISG, could increase ICE basis average efficiency from 18.2% to 32% (=/- 5%).

3) The ICE other losses, i.e. 32% (+/- 5%) remains to be recouperated.

If using some of the energy lost in exhaust heat could increase the ICE efficiency by another 15%, this could, with (2) above, raise ICE efficiency from 30-32% to about 45%. Energy to the wheels could go from 12.6% to something close to 40% and fuel consumption could be reduced.

Every 5%, 10%, 15% should not be overlooked for those who will delay going electric for decades.

From what it says and it's rather vague, it is an open cycle air power Stirling engine that runs on exhaust heat.

It is not easy to recover waste heat from the exhaust system, they say how they compress in the aiar before feeding the exchanger. The problem is thay it adds a significant complexity to the engine (still is simpler than adding a steam engine) for a relativily limited improvement in efficiency, not sure that the 15% is enough and you can get this using an Atkison or super Atkinson design and it will be simpler than that.

Exhaust heat of ICE is too low for Brayton or Ericksson cycle engines to get any kind of power or efficiency out of it. For adequate efficiency and power, the temp of heat source must be around 1500 degrees Kelvin to make it worthwhile (practical in the real world). That's why BMW and Honda have made prototypes of autos having Rankine-cycle steam engine waste heat recuperation, instead of going the compressed-air route.

However, the "Cyclone Power" waste heat recuperation engine (modified Rankine, or Schoell cycle) can generate as much as 3000 psi of steam pressure at 647 degrees Kelvin, in a very compact size, making it ideal for exhaust heat recuperation of large Diesel engines in trucks, stationary genset, or marine Diesel engines.

For private autos, just stick in it a Cyclone Power engine that does not even require a transmission, for ultra simplicity, to achieve ~34-36% thermal efficiency overall, from tank to wheel. This is twice the efficiency of a typical non-hybrid ICE cars at 18% efficiency, and comparable with the HEV Prius at 35-37% tank-to-wheel efficiency.

"Damn those cheese eating surrender monkeys ;-)"

But I'm not a racist.

Does anyone know anything about the second law of thermodynamics? It is amusing that so many people overlook the fact that heat engines are limited in efficiency by fundamental physics...

informationquelle:  Yes, some of us have debunked schemes based on detailed criticisms using the 2nd Law.

This isn't one of them.  It's well-known that the exhaust of internal combustion engines carries heat at rather high temperature*.  This heat is more than sufficient to run a heat engine; this has been the subject of research since the 1970's oil price shocks.  If someone can make an Erricson-cycle add-on which can be built into conventional engine blocks, they may well have a winner.

One other twist:  any such system is going to have a fair amount of compressed-air plumbing to and from the heat exchanger.  This represents a store of energy which might be used for stop-start operation.

* The heat of combustion cannot be fully harnessed by expansion because the ratio of specific heats of combustion gases increases, and the temperature falls less during expansion than it rises during compression.

>> It's well-known that the exhaust of internal combustion engines carries heat at rather high temperature*. This heat is more than sufficient to run a heat engine; this has been the subject of research since the 1970's oil price shocks. If someone can make an Erricson-cycle add-on which can be built into conventional engine blocks, they may well have a winner.

Ericsson-cycle engine has inferior power density and has not been practical in comparison to Otto, Brayton, or Diesel cycle. In other words, the Ericsson-cycle engine will be far too bulky for the power output desired. A gasoline automobile engine can produce high exhaust temp at ~800 Celsius at high load due to lower expansion ratio, but, at low-load typical at highway cruise for a car, the higher expansion ratio due to lower manifold pressure will cause a much lower exhaust gas temperature. Atkinson-cycle engine and Diesel engine produce cooler exhaust than gasoline engines even at high loads thus making exhaust heat recycling even less practical.

A serial hybrid setup, either electric or hydraulic, powered by a free piston HCCI engine would obviate the need for exhaust heat recycling. The very high compression ratio of the free piston engine (hence high expansion ratio) and the low friction, can raise engine efficiency to above 50% without any complicated add-on devices, while producing cool exhaust.

Alternatively, a Cyclone Power engine (Schoell cycle) external combustion has such an efficient built-in heat recycling system that produces cool exhaust at 120-200 Celsius.

By your answer you clearly don't understand the second law.

First, remove the beam that is in your own eye....

Availability destruction in IC engines is often very high. The portion of available energy in the exhaust is not as great as simplistic 1st law energy conservation sums predict.

If you turn the problem around you would be better served to improve the efficiency of the engine.

This energy is free.  The only consideration is the weight and expense of the machine to capture it.