Re: Performance and fans

Balamurugan J. (JB@rect.ernet.in)
Mon, 28 Apr 1997 10:51:51 IST+530

>
> In terms of wear and tear as well as efficiency, the electric fan is
> superior. As any one is familiar with racing, reducing rotational mass
> is the equivelent of taking off two times the weight (at least) of
> stationary mass. (IE: ten pounds off each tire = 80 pounds inside car).
>
>
> In the case of unsprung weight (tires) the benifits are even greater as
> the suspension is allowed to work faster, by reducing the weight
> reacting to the forces acting on the tire.
>
> This is same scenario can also be applied to the engines ability to
> rev. With less rotational mass to accerlerate, the engine is allowed
> to rev quicker. Lightened flywheels are the usual way to achieve this.
> The electro-magnetic assemlies, which are quite heavy, are constantly
> having to be accelerated and decelerated with the revs of the motor,
> this is wasted energy.
>
I agree

> The electric fan uses no energy when not in use, is stationary mass
> when idle (very light in comparison), and very efficient when
> considering the efficiency of the combustion engine.
>
But it has to be remembered that the electric energy used by the fan
ultimately comes from the same internal combustion engine, with the
power derived through the same belt, and hence the overall energy
efficiency cannot be higher.

The real plus points of the electric fan are

low dead weight;
operation only when needed;
non dependence on vehicle speed for cooling efficiency;
Low wear and tear on pump bearing ( due to elimination of this mass
from the shaft ).

jb
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