Environmental Engineering Reference
In-Depth Information
40.0
35.0
SUV
Mid-size car
Micro car
30.0
25.0
20.0
15.0
10.0
5.0
0.0
80
100
120
140
160
180
200
220
velocity [km*h ]
-1
Fig. 7.2
Fuel consumption depending on velocity
7.1.3 Rolling Resistance
The rolling resistance of tires impacts the total fuel consumption in passenger cars
by approximately 10-15%. Modern commercial vehicles automatically monitor
the pressure in the tires. Smooth running tires and light running oils decrease
rolling resistance and lead to lower fuel consumption and exhaust gas emissions.
The rolling friction of the tires is affected by the applied construction, the used
material and the internal pressure. At 20 km h
-1
(12.4 mi hr
-1
), rolling resistance
is nearly 100% of the external resistance acting on the car and still makes up 60%
of the external resistance at 50 km h
-1
(31.1 mi hr
-1
). The fuel saving rates are
smaller but also similar in heavy commercial vehicles [
4
].
7.2 Aerodynamics of Airplanes
The aerodynamics of airplanes depends on the interaction of moving air with the
surface of the aircraft [
5
]. The main resistance factors are:
• Fuselage: 0.02-0.05;
• Engine and nacelle: 0.10-0.15;
• Tail unit with horizontal and vertical stabilizers: 0.01-0.02;
• Wing and connecting parts: 0.2-0.3; and
• Winglet: 0.01.
Improved aerodynamics reduces fuel consumption and thus also CO
2
,NO,NO
2
and particle emissions. The aerodynamic drag depends on the quality of the sur-
face, similar to vehicles and ships.
The main ways to reduce the fuel consumption of airplanes are laminar wings,
laminar fins, laminar nacelles, smooth surfaces, riblet skins, wingtips, and variable
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