Assessment of Propulsion Units
The above-mentioned assessment criteria are applied to the following propulsions:
Otto engine in naturally aspirated version (OI)
Otto engine with exhaust-gas turbocharging (OT)
Diesel engine in naturally aspirated (DI)
Diesel engine with exhaust-gas turbocharging (DT)
Wankel engine (WE)
Gas turbine with internal combustion (GT)
Electric motor with conventional lead battery (EL)
An assessment of 10 points implies: very good, with 0 points: very unfavorable.
a) Operating Behavior
The delivery map of the different propulsions is shown in the figure. A common characteristic line is drawn in for all reciprocating internal combustion engines. This characteristic line, like the other characteristic lines, represents the typical behavior.
The electric drive turns out to be significantly superior both in permanent operation as well as during the start phase, i.e., for short-term overload. The characteristic of the two-shaft gas turbine can be used rather well for vehicle propulsion. Reciprocating engines have a satisfactory behavior only when they are connected with characteristic converters.
Without going into further detail here, the operating behavior of the various propulsion units is presented.
The torque lag of engines with exhaust-gas turbocharger in the lower speed range is explained by the (smaller) difference in points between supercharged and naturally aspirated versions. As a result of the usual employment of characteristic converters in all propulsions, the torque characteristic and start-up behavior are of limited significance.
When dealing with the control behavior and startability, the electric drive is most advantageous. The control behavior of naturally aspirated engines just slightly differs. The characteristic sluggish response of the turbocharged versions leads to their low assessment. The overall control behavior of the gas turbine when compared with today's economically feasible technology is poor. In the start phase, only the pre-chamber diesel engine and the gas turbine engine require a preheating time.