Randall wrote:
>> Does
>> anyone have suggestions on replacement radiators for a TR4A?
>>
>
> According to my radiator man, aluminum radiators aren't any more efficient
> than copper, and possibly even less so. That makes sense to me, since
> aluminum is both a poorer conductor of heat, and weaker than copper (hence
> needs to be thicker for the same strength). The main advantage of aluminum
> is cost.
>
>
I suspect that some of the cost advantage is lost in the additional
sectional thicknesses required for aluminum. Copper radiators can be
made in rather thin sections, and work better that way, just so long as
they are designed in such a way that the thin sections don't work-harden
and crack. (I recall seeing a design from a now-defunct company that
made the core runners socket into rubberized receivers in the header and
footer tanks, and that struck me as a good way to isolate the core from
vibration and heat-cycle stresses.)
There are two major considerations for material selection when it comes
to heat exchange (apart from structural considerations). The first is
the coefficient for heat transfer off the surface, and, second, the
coefficient for heat transfer through the material. Off the surface,
rusty cast iron is probably the best, but not so good through the
material (this makes sense, given that the amount of surface area per
square inch would be very high). Heat transfer through aluminum is very
high on the list, if not the best of commonly available materials, but
not very good off the surface (about one-quarter the value for rusty
cast-iron and poorer than copper). That's probably why aluminum radiator
cores seem to have an awful lot of fin area as compared to copper-cored
radiators with similar heat rejection properties.
Nevertheless, many heavy-duty diesel applications are going to aluminum
radiators, because the major radiator manufacturers are claiming higher
efficiencies because of improvements in fin-to-runner welding. M'self,
I think they consume a bit more power getting air through them, but, the
heat rejection tests I've seen show them to be comparable to older
copper radiators.
Cheers.
--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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