06.08.2013 Views

Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

( D3<br />

− D2)<br />

1<br />

fea = =<br />

Eq. (3)<br />

FCa FCa<br />

while the fuel efficiency computed using in<strong>for</strong>mation obtained from the vehicle databus would have<br />

been:<br />

( D3<br />

− D2)<br />

1<br />

feb = =<br />

Eq. (4)<br />

FCb FCb<br />

Replacing Eq. (2) into (4) and defining q = 1/p then:<br />

1<br />

feb = =<br />

FCa × p<br />

q<br />

FCa<br />

Eq. (5)<br />

Consider now truck T’ which is identical to truck T (i.e., it has the same databus configuration and<br />

electronics as well as the same on-board sensors) but it has a different tire configuration. Assume<br />

also that T’ made the same trip, t, as T did. Fig. 64 shows the fuel consumption per unit of distance<br />

traveled <strong>for</strong> truck T’. Since both vehicles have the same databus and electronics, it can be assumed<br />

that the fuel consumption computed using in<strong>for</strong>mation collected from the databus of truck T’ would<br />

be larger that the actual fuel consumption by a factor of p. Using the same logic as in the case of<br />

truck T, it is possible to determine the actual fuel efficiency <strong>for</strong> truck T <strong>for</strong> in trip t23 as shown in Eq.<br />

(6):<br />

( D3<br />

− D2)<br />

1<br />

fea '=<br />

=<br />

Eq. (6)<br />

FCa'<br />

FCa'<br />

and the fuel efficiency computed using the in<strong>for</strong>mation from the databus as:<br />

1 q<br />

feb '=<br />

=<br />

Eq. (7)<br />

FCa'×<br />

p FCa'<br />

Suppose now that in order to compare the effect of a given characteristic (e.g., type of tires) on the<br />

fuel efficiency reported by T and T’, the percentage difference in fuel efficiency between trucks T and<br />

T’ is computed. Using the actual fuel efficiencies (i.e., fuel efficiencies calculated with no errors)<br />

this percentage difference would be:<br />

q q<br />

( − )<br />

( fea'−<br />

fea)<br />

100 '<br />

⎛ FCa ⎞<br />

DFEt = × = FCa FCa × 100 = ⎜ −1⎟<br />

× 100 Eq. (8)<br />

fea<br />

q<br />

⎝ FCa'<br />

⎠<br />

FCa<br />

which was obtained with the help of Eqs. (3) and (6). If this percentage difference in fuel efficiencies<br />

is computed using the erroneous (i.e., overestimated) databus fuel consumption then:<br />

77

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!