Waste Heat Recovery System Receives Powertrain Innovation of the Year Award
18 November 2008
|Cutaway diagram of the heat2power system mounted on an engine. Click to enlarge.|
The Paris, France-based developer of a waste heat recovery (WHR) system, heat2power, won the Powertrain Innovation of the Year Award at the Professional Motorsport World Expo in Cologne (11-13 November) with its Thermal Energy Recovery System (TERS). heat2power says that its WHR system can provide fuel savings of 15-35% under all driving conditions at a cost of approximately 30% more than a comparable turbocharged gasoline engine.
The heat2power system uses one or more cylinders for the regeneration of waste heat. These cylinders can be in replacement of the combustion cylinders inside an existing engine or as an add-on module that is connected to the engine by means of a gear set or a belt drive. It is also possible to have no mechanical linkage between the combustion engine and the WHR unit in case the power from the regeneration unit is taken off electrically.
|System layout of a heat2power add-in configuration and power flows. Click to enlarge.|
The heat2power system, like other thermodynamic cycles, intakes and compresses a gas, heats it and allows it to it expand. The difference between an ICE and the heat2power system is that the heat input is not by a combustion inside the cylinder but by heat exchange external to the cylinder.
The regeneration device comprises:
One or more piston, cylinder and rod groups, with 4 valves per cylinder, driven by standard camshafts;
One gas-gas heat exchanger; and
One dedicated boosting turbocharger.
|Specific fuel consumption for conventional engine (left) and engine with heat2power (right). Click to enlarge.|
After the expansion stroke, the air is released at low temperatures (250-300° C instead of 600-950°C). The heat exchanger in the exhaust is placed after the catalyst (gasoline vehicles) or after the particle filter (diesel vehicles), allowing the exhaust aftertreatment system to be unaffected. heat2power recommends application of thermal insulation of the exhaust manifold and the first part of the exhaust and catalyst/DPF so that a maximum amount of heat is available for the regeneration process.
The system is compatible with all fuel types (e.g., diesel, gasoline, ethanol, CNG, LPG, etc.) and complementary with hybrid electric powertrain concepts.
heat2power is seeking partners for prototyping and testing of its devices.
Damn those cheese eating surrender monkeys ;-)
Posted by: DS | 18 November 2008 at 01:26 PM
If this works out, it is phenomenal! 15-30% for a more expensive engine.
Imagine an I4 engine with 3 ICE cylinders and one heat cylinder.
It would also work well with hybridization - hybridization for the city work and heat recovery for the rural sections!
Vive la France!
Posted by: mahonj | 18 November 2008 at 04:09 PM
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.
Posted by: HarveyD | 18 November 2008 at 05:31 PM
I'm struggling with how this one works...
Am I simply seeing double expansion via non firing cylinders? If I am, I'm going to be pissed because I had the same idea 5 years ago and figured it would never work because it wouldn't extract enough power.
Perhaps the second loop is sealed and has some sort of liquid with a low boiling point? Please tell me that's the case and its not just friggin air...
Posted by: GreenPlease | 18 November 2008 at 05:40 PM
From what it says and it's rather vague, it is an open cycle air power Stirling engine that runs on exhaust heat.
Posted by: Brn | 18 November 2008 at 05:57 PM
Hmmm. What does the 'dedicated boosting turbocharger' do? More detail would be nice. This is apparently a Stirling cycle heat engine running off exhaust heat, but then a turbocharger runs off exhaust heat as well, so now you have two devices extracting heat from the exhaust. Wouldn't the turbocharger steal energy from Stirling engine?
Posted by: Nick | 18 November 2008 at 07:20 PM
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.
Posted by: Treehugger | 18 November 2008 at 07:24 PM
"From what it says and it's rather vague, it is an open cycle air power Stirling engine that runs on exhaust heat."
I believe an open cycle Stirling is called Ericsson cycle.
Proe Power Systems
Posted by: DS | 18 November 2008 at 07:44 PM
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.
Posted by: Roger Pham | 18 November 2008 at 08:33 PM
Can somebody tel me what is difference as compare to multi extension stem engine?
Are they forget 200 year old classic steam multi expander?
That a very simplistic implementation of steam multi expender.
The expander piston used to do that work should have bigger diameter to better utilized the available exhaust pressure. The system should have two expander not just one, so total of 5 cylinder.
It jut me or I see flow in the design. If you utilize 3 cylinder one expansion cycle is lost.
If I will build engine base on that idea I will closely follow the the old steam engine design. It will have 3 cylinder with only one with ICE function and the other two will be expander. Each of the cylinder will have different diameter progressively increase (combustion cylinder will have the smallest diameter).
Posted by: mki | 18 November 2008 at 09:23 PM
"Damn those cheese eating surrender monkeys ;-)"
But I'm not a racist.
Posted by: | 18 November 2008 at 11:47 PM
Even prototype not available!!! Who could give them award without working prototype? I myself can create lot of theories including "perpetum mobile".
Posted by: Darius | 19 November 2008 at 12:11 AM
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...
Posted by: informationquelle | 19 November 2008 at 01:53 AM
An engine running 3 ICE cylinders and 1 exhaust heat cylinder is going to be as rough as a dog.
My vote still goes to organic rankine cycle for the 21st century.
Posted by: clett | 19 November 2008 at 03:09 AM
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.
Posted by: Engineer-Poet | 21 November 2008 at 06:37 AM
Make that "ratio of specific heats of combustion gases decreases".
Posted by: Engineer-Poet | 21 November 2008 at 06:38 AM
>> 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.
Posted by: Roger Pham | 22 November 2008 at 12:47 PM
By your answer you clearly don't understand the second law. 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. I challenge anyone to show the second law estimations for these systems. More often than not the results for these devices fall way short of the predictions because the second law is ignored. When a real working prototype is produced and the results are repeatable we can say how well it works.
If you turn the problem around you would be better served to improve the efficiency of the engine.
Posted by: informationquelle | 23 November 2008 at 12:18 PM
First, remove the beam that is in your own eye....Both true and totally irrelevant. The temperature of ICE exhaust gas is quite high at full load. The gas may have no energy available through further expansion, but the heat is still sufficient to drive a heat engine.
Even after you've gone to a Miller or Atkinson cycle, you've still got hot exhaust gas; the air charge has γ of about 1.4, but the combustion products have γ around 1.27 and are not going to cool by the same ratio as the charge is heated by compression. Some of this energy is not available at all (entropy increase in combustion, latent heat of water vapor), but the sensible heat of the fully expanded exhaust gas can heat another working fluid to power a heat engine.
This energy is free. The only consideration is the weight and expense of the machine to capture it.
Posted by: Engineer-Poet | 04 December 2008 at 07:49 AM
I am very happy to see reasonable comment from Mr Poet : "This energy is free. The only consideration is the weight and expense of the machine to capture it"
All I can tell you is that Heat2power cycle efficiency and also the global efficiency are very good, compared to the available technologies (Rankine cycle or ORC for example).
The automotive industry which evaluated the technology accords to estimate a very low cost and very high power to mass density.
A prototype of this technology will be on the dyno begining of february. The pilot customers will be able to share Heat2power performance results during early 2009.
Posted by: Fred | 09 December 2008 at 03:10 AM