Page 181 - Automotive Engineering Powertrain Chassis System and Vehicle Body

Hybrid vehicle design CHAPTER 7.1

Fig. 7.1-9 Audi Quattro hybrid: (a) package; (b) speed/torque map; (c) simulated performance test; (d) estimated future performance.

While the vehicle will operate at zero emissions in the speeds. Typically 30–50 kW is required for passenger
above mode of operation, if the journey length is greater vehicles operating at motorway speeds.
than the range, the gas turbine engine must be operated It is currently not possible to store sufficient energy in
to allow the batteries to be recharged. Again, ‘advanced’ a battery or any other accumulator such as a flywheel to
lead–acid batteries are required to allow the full power of give anywhere near an acceptable range at such a dis-
the gas turbine to be absorbed, hence preventing it from charge rate. The gas turbine must hence operate con-
operating in a part load condition. Although the vehicle tinuously although not necessarily at constant power.
will not be ZEV in this mode, the composite emissions Generally, the power output of the gas turbine will be
will still meet the ultra-low emission vehicle (ULEV) matched to the vehicle power demand although some
requirements due to the inherent low emission charac- form of smoothing of the power demand will be needed
teristics of the gas turbine engine. Combustion in the gas to avoid rapid cycling of the gas turbine engine. Any
turbine is steady state as compared to the intermittent excess power generated or power deficit will be handled
combustion in IC engines and is always lean burn. The by absorbing this or taking this from the battery. Since
potential for further reduction of small gas turbine the power demand is high and continuous, the engine
emissions is also very good and has been demonstrated in must be able to produce such power continuously. If an
much larger machines in the industrial sector. In highway IC engine generator set was to be used instead of the gas
usage, operation requires a much greater rate of energy turbine and high speed generator, the resulting machin-
consumption due to the increased average vehicle ery would be too voluminous and heavy for the series

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