Objective
To perfect a system converting heat contained in the exhaust of lorries to mechanical energy which is used on the drive shaft. In comparison with a lorry not equipped with such a system, 13% or 5 L/100 Km would be saved giving a project payback of just under 6 years.
The detailed study showed that the adoption of a rankine cycle to recover diesel lorry exhaust gas heat would only be economic on current motor designs if the price of fuel were to increase substantially.
1. Following increasing efficiency of engines between 1979 and 1983, the temperature of exhaust gases has fallen by 90 deg. C. and potential heat recovery is less than the original design indicated. The savings would amount to only 8% or 3 L/100 Km
2. The current structure of vehicles does not allow different parts of the system to be installed for either safety of aerodynamic requirements.
3. As far as heat vectors are concerned fluorinol is the safest and the most stable, but prohibitively expensive; toluene is cheap but cannot be used due to its inflammability.
4. Even if the above problems could be soveld. The system is still too expensive. Taking the 1984 diesel oil price in France, a lorry would have to travel 350 000 Km before the system paid for itself. The average distance travelled per year for most vehicles is not sufficient.
The system is made up of the following components:
a. a steam generator situated in the place of the auxiliary fuel tank.
b. a condensor placed above the driver's cabin and facing the direction of travel thereby benefiting from the forced draft. Ventilation is also guaranteed by independant fans.
c. a turbine group (30 Kw - 40 000 rpm) - speed reduction gear - regenerators - a pump, the position of which is such to modify standard lorries as little as possible. Coupling between the turbine's speed reduction gear and the crank shaft is by way of a belt drive. For a 300 hp vehicle this system could save between 4 and 5.5 L/100 Km according to how it is used. The savings correspond to a basic engine with good performance (150 gm diesel/hp/hr). Naturally if this additional power is used to increase the average speed of the vehicle then the savings would be reduced.
The investment per lorry is 50 000 FF (1981) and the system's lifetime is 750 000 Km.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
69800 St. Priest Cedex
France