Besides the fact that it is my company
and that we try to get into F1, I also wish to raise the awareness of the potential of WHR in general. It is still generally just not well understood yet what can be done with waste power flows and how much this can influence fuel economy. That is why I put a benchmark page with lots of information on other concepts as well. In total I identified more than 40 technologies to regenerate waste heat and there are quite some diffences between them. That is in terms of efficiency, cost, specific power, complexity, environmental impact, safety and so on.
The term TERS did not exist before my article and I wanted to put some term in place that is easy to pronounce which is not the case with WHR. As KERS is already a common term, TERS was the most logical to pick.
I truely believe that there is a big future for TERS, both in racing and in road applications and powergeneration. BMW has already presented the Turbosteamer concept and a good article about it has just appeared in MTZ (Motor Technisches Zeitschrift) of July 2008. It shows the distribution of waste heat flows between exhaust and cooling system for a gasoline engine on a 3-series and also the amount of added power generated by the TERS. It is the order of 12 to 15% over the major part of the RPM and torque range which in my opinion is a very good performance.
Of all the technologies for fuel economy that I have looked into I believe that TERS, downsizing (turbocharging), variable compression ratio and overexpansion (Gomecsys for example) are the most effective ones, and combinations are of course possible. For part load the VCR and downsizing are very good. For "only full load" or "binary driving style" as in F1 the VCR brings nothing though. Overexpansion does however and I see a good potential for a combination of this with TERS as there will always be lots of power available in the exhaust. As or turbocharging we all know it is going to bring a few percent fuel economy and we will quite probably see this coming back to F1.
Increasing the speed of combustion is in my opinion also something that can help improving fuel economy as less fuel would be wasted by blowing it away through the exhaust. (remember why we put catalyst converters in the exhaust?). Hydrogen addition to improve combustion (also in lean mixtures for part load applications) has been worked on in the past and positive results have been shown by Prof Eran Sher of Ben Gurion University and by Prof Radu Chiriac of University of Bucurest. Only small amounts of Hydrogen are actually needed to improve fuel economy and the effect relies on the higher flame speed of hydrogen (8 times as fast as gasoline) to bring the full chamber of gasoline to combustion. The results I have seen are for RPM ranges corresponding to road vehicles so I guess that the effect will be even more beneficial on high-revving Formula 1 engines.
Then there is organometallic combustion that seems to improve fuel economy by increased flamespeed. I don't know what the effect of the added metals in the fuel are on the environment but the idea to integrate a combustion catalyst in the fuel itself does not sound odd. I have however quite little scientific information about this that I can share with you. Please forgive me.
Another method to improve efficiency I have read about is copper coating (Journal of applied sciences 7, 2007, pages 1633 and on) but the test basically were done at low RPM (around 1600 RPM) so I cannot estimate the effect at high RPM. I suggest you Google for "Krishnamoorthy and Chandrasekaran copper" to find the paper.
Apart from regenerating the waste heat you can also try to reduce it to the max. "Adiabatic engines" are what you optimally would like to have. It seems that the Shell people applied this approach in the Fuel economy record of 376.59 MPG in 1973 with a modified Opel. This was listed in the Guiness book of records at the time and I can recommend reading "Fuel Economy of the Gasoline Engine" (ISBN 0-470-99132-1) that was published by John Wiley & Sons, New York, in 1977 (written by the same Shell people). Material and lubricant properties in general keep you from applying the adiabatic principle because of too high temperatures. But times are changing and materials get better and better...
There are a few main rules to retain when you want to achieve fuel economy:
- For good thermodynamic efficiency you need high compression ratio.
- Have all the fuel burn exactly when you want it (that is what Diesotto-HCCI is doing).
- Know where the heat losses are and work on reducing them or on regenerating them (huge potential)
- Minimize mechanical losses (=friction); F1 is already quite good in this.
- Minimize oil churning losses (dry sump)
- Optimize engine internal aerodynamics
be educated and creative.