Fall
Semester 2008
CEE
3604

Homework #3 solution
Interpretation of Sensitivity Tests
Test 1: Decreasing the desired speed to 20 km/hr
The fuel consumption is a concave curve and a function of speed. When speed decreases
from 50 to 20 km/h, the engine consumes more fuel per km (inefficient fuel
consumption). Since we are using the same annual utilization (hrs/year) the distance
traveled (AKM) will be less and so interest and depreciation go up per 1000 km.
However other parameters remain the same as base case.
Test 2: Increasing desired speed to 100 km/h
With the increased speed, the fuel consumption would be higher than that at a speed of 50
km/h since the engine needs to generate more power to overcome air resistance and partly
resistance forces at a faster rate. However in contrast to test 1, higher speed means the
distance traveled (AKM) is higher and consequently less depreciation and interest costs
per 1000 km.
Test 3: Increase payload to 400 kg
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 Fall '08
 KATZ
 Internal combustion engine, Miles per hour, 75%, 50 km/h, 20 km/h, 100 km/h

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