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French start-up Heat2power has been making a little noise in the Hexagone thanks to a new technology that increases fuel mileage using heat energy otherwise dissipated via the exhaust pipe. There are others that use a similar system, but the company claims that their device captures even more energy. The basics include installing an additional cylinder linked to the crankshaft with a clutch that is powered by exhaust heat. The exhaust gases circulate inside a heat exchanger linked to a closed-circuit filled with compressed air. Hot air enters the additional cylinder. Once it has moved the piston, the air goes to an intercooler and returns to the heating unit forming a closed circuit. The system is compatible with any ICE engine, the company claims. Their numbers also say the device reduces up to fuel consumption 20 percent in urban driving and 35 percent on the highway. The company claims that the additional cost for a car is only 300-400 euros.

[Source: Heat2power]

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    • 1 Second Ago
      • 5 Years Ago
      If it takes all that heat out of the exhaust, how do you keep the catalytic converter lit?
        • 5 Years Ago
        Downstream fuel injection and ignition. afterburners for your car.
        • 5 Years Ago
        A few decades perhaps. Not a few years.
      • 5 Years Ago
      Honda considered doing something similar to this using a Rankine Cycle


      Of course consider that this would be useless when a Hybrid is running on battery only with the engine shut off. I am sure they've determined it simply is not worth the extra cost to implement these features or else they would have already done it.

      This design presented here appears to be based upon the Carnot Cycle.
      • 5 Years Ago
      If their claims are true, that is a significant breakthrough. The Europeans are pretty resourceful. Why aren't any of these new technologies coming from the US? I guess it's mostly because we care far more about huge horsepower than automotive efficiency.
      • 5 Years Ago
      Have they built one of these, or is it just a CAD rendering?

      I suspect they will find that the efficiency gain is smaller and the cost is larger than those stated in the article.

      BTW - There is no new technology here - this is an external combustion engine, a clutch and a control system.

      • 5 Years Ago
      Heat could be turned directly into electricity.

      • 5 Years Ago

      Does this recycle power to only one cylinder, or can it turbo/supercharge all the cylinders? Does it gain efficiency by heating (and fully vaporizing) the fuel?
      • 5 Years Ago
      I guess you have read the contents of the heat2power website but you may have missed the diagram that shows that the heat exchanger is positioned after the catalyst converter. In such manner the heat2power does not intervene with the exhaust gas aftertreatment system and it also benefits from the exothermal reactions that take place in the catalyst. Meanwhile the system gives a marginal extra backpressure to the engine so that its tuning doesn't require extra attention on this aspect. This is specially interesting for racing engines that can loose a lot of power if backpressure is added.

      The image is a CAD drawing. The real thing looks slightly different now.

      There are alternatives in the US. You may have not found the link on the heat2power website to the DEER conferences where you can find presentations about Organic Rankine Cycles and Thermoelectrics projects at John Deere, Caterpillar and Cummins. There is also the Cyclone engine that claims to run on waste heat.

      Well known alternatives to the heat2power concept are BMW's Turbosteamer, Honda's Rankine WHR and Toyota's Stirling WHR. At heat2power we have worked on a simple and low cost system so that adoption in an industrial environment is as easy as possible, while offering high power density, good regeneration efficiency, no use of additional liquids on the vehicle, ease of maintenance, low cost and good controlability to the end customer. We have therefor decided to make it run on air.

      We expect a heat2power unit as an add-on to cost around 450€ in series production version. The fuel economy obtained would indeed make it profitable in a short time. The heat2power technology would thus be worth the extra cost. And it is not a few decades away, believe me.

      Feel free to surf around on the heat2power website again to find the answers to the questions that may remain. And you can always contact us directly for more information.

      With best regards from Paris

      Randolph Toom
      Managing director of heat2power