[TR] TR4A Radiator

[Michael Porter]

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....