August 26th, 2010 | 
Author: Car Giants Seek To Increase Engine Power From Waste Heat
One might think that the steam engine is an outdated technology that had its heyday centuries ago but in fact steam is once again a hot topic with vehicle manufacturers. Indeed the next generation of hybrid cars and trucks may incorporate some form of steam power. Honda for example has just released details of a new prototype hybrid car that recharges its battery using a steam engine that exploits waste heat from the exhaust pipe.
Typical cars only convert about a quarter of the energy produced during combustion into work with the rest being lost as heat. Honda has managed to increase this efficiency by 4 to nearly 29 by using some of this lost heat to generate electricity.
Hondas heatrecovery system is based on the Rankine cycle which is also used in most steamdriven power plants. First heat from the car’s catalytic converter is used to boil water. The hightemperature steam 400500 C produced then turns an electric generator before a condenser finally cools the steam back into water.
According to Honda under normal driving conditions the steam system recovered three times as much electric power as the hybrid’s regenerative braking system. Unfortunately however the 4 improvement in overall vehicle efficiency that resulted is not high enough to warrant commercialization Honda claims.
Honda is not the only manufacturer interested in incorporating waste heat recovery into vehicle design. BMW for example is working on a steambased unit that generates additional mechanical power rather than electricity. In lab tests their socalled turbosteamer reduced fuel consumption by as much as 15.
It may be some time however before waste heat recovery reaches the mass market because typical car drivers would probably not make a big enough saving on fuel to justify the extra several thousand dollars that these systems would presumably add to the price of a vehicle.
But the situation is different for longhaul truckers who often spend over 100000 per year on fuel. Indeed several dieselengine manufacturers are testing ways of recycling lost heat with interest being driven by fuel prices and emissions reduction.
The engine maker Cummins Inc is also working on a Rankinecycle system that uses a lowboiling point organic fluid which they say performs better than other thermodynamic models such as the Stirling cycle or the gas turbine.
The Rankine cycle can convert up to 20 of the wasted heat into useful energy but dealing with the 80 that is not used poses a big challenge. Cummins Inc. plans to have a full working prototype by mid2009 and hope to make the system available to customers by 2013.
About the writer:nbsp;nbsp;Bill Bailey is freelance writer living in the east of England. Bill specialises in writing articles on finance shopping cars computers and travel.
More of Bill’s articles can be found on http://www.schnafflehound.com
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