I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned that
a) it's hard to find specs for radiator performance, and b) a mechanic says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

How many Btu/h can an auto radiator move from 150 F air to 140 F water,
using its electric fan, with no wind? An engine that makes 200 HP at 25%
efficiency (unlikely with no motion :-) would burn 800 HP of gas. If 25%
of the heat leaves from 200 F water to 100 F air via the radiator, the air-
water thermal conductance is 0.25x800x746x3.41/(200-100) = 5100 Btu/h-F,
good compared to a 2'x2' all-copper $200 MagicAire 2347 duct heat exchanger
that moves 45K Btu/h from 125 F water to 1400 cfm of 68 F air with a 0.1
"H20 pressure drop.

Antifreeze would be expensive for a 1000 gallon heat storage tank, and
an antifreeze heat exchange loop would add to the cost and lower efficiency.
How much antifreeze do we need just to prevent corrosion? Is there some
corrosion inhibitor we can use at a low concentration?

Nick

wrote in message
...
I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned
that
a) it's hard to find specs for radiator performance, and b) a mechanic
says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

How many Btu/h can an auto radiator move from 150 F air to 140 F water,
using its electric fan, with no wind? An engine that makes 200 HP at 25%
efficiency (unlikely with no motion :-) would burn 800 HP of gas. If 25%
of the heat leaves from 200 F water to 100 F air via the radiator, the
air-
water thermal conductance is 0.25x800x746x3.41/(200-100) = 5100 Btu/h-F,
good compared to a 2'x2' all-copper $200 MagicAire 2347 duct heat
exchanger
that moves 45K Btu/h from 125 F water to 1400 cfm of 68 F air with a 0.1
"H20 pressure drop.

Antifreeze would be expensive for a 1000 gallon heat storage tank, and
an antifreeze heat exchange loop would add to the cost and lower
efficiency.
How much antifreeze do we need just to prevent corrosion? Is there some
corrosion inhibitor we can use at a low concentration?

Nick


Why use Aluminium? I wouldn't have thought it would be hard to find an old
copper one which will.
A. Be a little more efficient
B. Won't have the corrosion problems Aluminium may have.
As you wont be running it under pressure even a leaky one should be easy
enough to patch up.

As for Aluminium corroding, if it's the only metal in the system I don't
think you will have a problem. If I was making something like this (and
someday I'd like to) and using second hand stuff I think I'd suck it and see
what happened.
Stuart

On Aug 24, 7:12 pm, "stu" wrote:
wrote in message

...



I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned
that
a) it's hard to find specs for radiator performance, and b) a mechanic
says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

How many Btu/h can an auto radiator move from 150 F air to 140 F water,
using its electric fan, with no wind? An engine that makes 200 HP at 25%
efficiency (unlikely with no motion :-) would burn 800 HP of gas. If 25%
of the heat leaves from 200 F water to 100 F air via the radiator, the
air-
water thermal conductance is 0.25x800x746x3.41/(200-100) = 5100 Btu/h-F,
good compared to a 2'x2' all-copper $200 MagicAire 2347 duct heat
exchanger
that moves 45K Btu/h from 125 F water to 1400 cfm of 68 F air with a 0.1
"H20 pressure drop.

Antifreeze would be expensive for a 1000 gallon heat storage tank, and
an antifreeze heat exchange loop would add to the cost and lower
efficiency.
How much antifreeze do we need just to prevent corrosion? Is there some
corrosion inhibitor we can use at a low concentration?

Nick

Why use Aluminium? I wouldn't have thought it would be hard to find an old
copper one which will.
A. Be a little more efficient
B. Won't have the corrosion problems Aluminium may have.
As you wont be running it under pressure even a leaky one should be easy
enough to patch up.

As for Aluminium corroding, if it's the only metal in the system I don't
think you will have a problem. If I was making something like this (and
someday I'd like to) and using second hand stuff I think I'd suck it and see
what happened.
Stuart

Be patient Nick, George will answer all.

Until then, consider the following. The radiator is based on the
constant flow of the water pump and the thermostat, which opens and
closes on a regular basis. If one were to take the engine, measure the
block and head temperatures, as well as the radiator fluid
temperatures, one would find the relationship between all of them.
Now, we know that a automobile engine with a failed thermostat will
malfunction in some way. If the thermostat is stuck open, the engine
will never ever warm up, thus giving us an indication that a typical
auto radiator is over designed for the application with a wide open
flow. If stuck closed, it will overheat.

Another similar way would be to take say, 200 degree water heated at
an even rate and flow it through the radiator and measure the
difference between the inlet and outlet at a given flow of fluid and
air through the radiator. I would suspect that you will need a much
lower flow than you expect to extract a given BTU without flow
regulation.

Feel free to take all of that out of context in any way you see fit.

wrote:
I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned that
a) it's hard to find specs for radiator performance, and b) a mechanic says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

How many Btu/h can an auto radiator move from 150 F air to 140 F water,
using its electric fan, with no wind? ...

For some detailed answers you might look at

Parametric studies on automotive radiators
Applied Thermal Engineering, Volume 27, Issues 11-12, August 2007, Pages
2033-2043
C. Oliet, A. Oliva, J. Castro and C.D. Pérez-Segarra

My gut feeling is performance won't be very good w/ only a 10F
temperature differential. In round numbers, an automotive radiator
operates on roughly a 100F difference or greater and except at idle, has
a pretty high airflow rate. Somebody else noted already they're well
over-designed for the minimum capacity in order to account for idling in
traffic on hot days w/ full A/C load, etc., but still the temperature
differences are around 200F for coolant and 100F for air temperatures
for the most part. Coolant flow rates are pretty high, as well.

dpb wrote:

wrote:

I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned that
a) it's hard to find specs for radiator performance, and b) a mechanic says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

An old all-copper car radiator might not corrode, but it might not have an
electric fan, and it might be hard to find one, and a replacement if needed.

How many Btu/h can an auto radiator move from 150 F air to 140 F water,
using its electric fan, with no wind? ...

For some detailed answers you might look at

Parametric studies on automotive radiators
Applied Thermal Engineering, Volume 27, Issues 11-12, August 2007, Pages
2033-2043 C. Oliet, A. Oliva, J. Castro and C.D. Pérez-Segarra

Aha. Thanks. Now where did I put the August issue...

My gut feeling is performance won't be very good w/ only a 10F
temperature differential.

I'd like to get 800 Btu/h-F, like a MagicAire 2347.

In round numbers, an automotive radiator operates on roughly a 100F
difference or greater and except at idle, has a pretty high airflow rate.

I'm wondering how it will do without wind, just its own fan.

Somebody else noted already they're well over-designed for the minimum
capacity in order to account for idling in traffic on hot days w/ full
A/C load, etc.,

At idle, it might have to dissipate 25% of 1 gph, about 30.5K Btu/h...

suppose ibut still the temperature differences are around 200F for coolant
and 100F for air temperatures for the most part.

G = 30.5K/(200-100) = 305 Btu/h-F?

Coolant flow rates are pretty high, as well.

If the thermostat's open.

Nick

wrote:
dpb wrote:

wrote:

I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned that
a) it's hard to find specs for radiator performance, and b) a mechanic says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

An old all-copper car radiator might not corrode, but it might not have an
electric fan, and it might be hard to find one, and a replacement if needed.

How many Btu/h can an auto radiator move from 150 F air to 140 F water,
using its electric fan, with no wind? ...
For some detailed answers you might look at

Parametric studies on automotive radiators
Applied Thermal Engineering, Volume 27, Issues 11-12, August 2007, Pages
2033-2043 C. Oliet, A. Oliva, J. Castro and C.D. Pérez-Segarra

Aha. Thanks. Now where did I put the August issue...

My gut feeling is performance won't be very good w/ only a 10F
temperature differential.

I'd like to get 800 Btu/h-F, like a MagicAire 2347.

In round numbers, an automotive radiator operates on roughly a 100F
difference or greater and except at idle, has a pretty high airflow rate.

I'm wondering how it will do without wind, just its own fan.

Well, as noted, they are designed for that as the next comment noted,
but still have about a 200F differential instead of your proposed 10F.

Somebody else noted already they're well over-designed for the minimum
capacity in order to account for idling in traffic on hot days w/ full
A/C load, etc.,

At idle, it might have to dissipate 25% of 1 gph, about 30.5K Btu/h...

suppose ibut still the temperature differences are around 200F for coolant
and 100F for air temperatures for the most part.

G = 30.5K/(200-100) = 305 Btu/h-F?

Coolant flow rates are pretty high, as well.

If the thermostat's open.

And if it ain't, it ain't doin' nuttin' useful...

--

On 24 Aug 2007 13:46:41 -0400, wrote:

I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator to heat water with hot sunspace air, but I'm concerned that
a) it's hard to find specs for radiator performance, and b) a mechanic says
an aluminum core radiator might crud up with corrosion in less than a year
with oxygenated water and no antifreeze.

Radiator performance is readily available from the manufacturers, if not in their
catalogs then from an inquiry. Have you looked at, say, Modine's website.

Antifreeze would be expensive for a 1000 gallon heat storage tank, and
an antifreeze heat exchange loop would add to the cost and lower efficiency.
How much antifreeze do we need just to prevent corrosion? Is there some
corrosion inhibitor we can use at a low concentration?

Coolant anti-corrosion/passivation chemical packages are available separate from
antifreeze. These are used to maintain the anti-corrosion protection in large volume
coolant systems where one wouldn't change many gallons of antifreeze just because the
protection package is depleted. Stationary diesels, locomotive engines, things like
that.

Additionally, the aluminum can be completely protected from corrosion by fresh water
using cathodic protection. There are many thousands of RV water heaters out there
with aluminum tanks that handle all sorts of tap water without corrosion. The reason
is the magnesium anode screwed into the tank. I would think that an RV replacement
anode could easily be fitted to an aluminum radiator.

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com -- best little blog on the net!
Tellico Plains, Occupied TN
I'm going crazy. Wanna come along?

daestrom wrote:

A general rule to reduce corrosion is to use water that has a low electrical
conductivity and not connect dissimilar metals. So if you use an Al
radiator, you might consider using short sections of hose to connect it to
copper piping. This helps minimize forming a galvanic cell that will
corrode the metal with a more negative potential.

We can do that, but mechanics say an electrically-isolated aluminum radiator
with rubber hoses and insulating brackets can still corrode (oxidize?) soon,
with nothing but water inside. My old boy scout canteen ended up heavily
pitted with white crud on the inside. I think this was oxidation vs mineral
deposits or galvanic corrosion, since there were no other metals involved.

Neon John wrote:

Coolant anti-corrosion/passivation chemical packages are available separate
from antifreeze. These are used to maintain the anti-corrosion protection
in large volume coolant systems where one wouldn't change many gallons of
antifreeze just because the protection package is depleted. Stationary
diesels, locomotive engines, things like that.

So far, I've only found Gunk anti-rust and water pump lube for car radiators,
$2 for 11 oz to protect 5 gallons or so, ie about $400 for 1000 gallons, and
a KPR VCI powder that costs about $20/lb and needs 0.25% concentration, ie
about $400 for 1000 gal. The tank will have a pressurized single-wall copper
pipe coil inside to make hot water for showers, so it would be nice to avoid
toxic tank water.

Additionally, the aluminum can be completely protected from corrosion by
fresh water using cathodic protection. There are many thousands of RV water
heaters out there with aluminum tanks that handle all sorts of tap water
without corrosion. The reason is the magnesium anode screwed into the tank.
I would think that an RV replacement anode could easily be fitted to
an aluminum radiator.

How long would it last? I gather it needn't be "fitted," just touching
the water and electrically connected to the aluminum. The 170 F tank water
won't change, so it won't have new minerals. It can absorb fresh oxygen,
esp since the radiator will drain down every day for freeze protection.
But it can't hold much oxygen, since it is hot. Then again, the corrosion
rate probably increases with temperature. The Farwest site mentions a 500
Wh/lb capacity for Mg rods used in pipelines, ie so many coulombs. How can
we turn that into a lifetime in a water heater with fresh O2 but no new
minerals? I've read that the oxide layer slows the corrosion rate, in air.

Nick

wrote

So far, I've only found Gunk anti-rust and water pump lube for car
radiators, $2 for 11 oz to protect 5 gallons or so, ie about $400 for
1000 gallons, and a KPR VCI powder that costs about $20/lb and
needs 0.25% concentration, ie about $400 for 1000 gal.

Nick, here's what I've been using in the heat storage system I built from your
suggestion of using old fuel oil tanks, some years ago. 2 parts to it, a rust
inhibitor, which costs about $15 a gallon and treats 300 gallons and an oxygen
scavenger, at about the same price per gallon. They have a chemical engineer
available, who may be able to answer any questions.

http://dwdavies.com/water_treatment/boilerkleen400.htm

and Stop-Rust #200 oxygen scavenger which is the very last item on the page.

http://dwdavies.com/water%5Ftreatment/

Hope you find this helpful.

Steve Young

On Sat, 25 Aug 2007 11:49:16 -0400, Neon John wrote:

..,.the aluminum can be completely protected from corrosion by fresh water
using cathodic protection. ...the magnesium anode screwed into the tank...

Aren't there also some active systems that do the same thing using electric
power instead of relying on cathodic action to provide the low voltage
differential? Of course they would stop working when the power went out, but
hopefully the amount of damage caused during the short power failure would not
amount to much.


Robert Scott
Ypsilanti, Michigan

Steve Young bowtieATbrightdslDOTnet wrote:

Nick, here's what I've been using in the heat storage system I built from your
suggestion of using old fuel oil tanks, some years ago. 2 parts to it, a rust
inhibitor, which costs about $15 a gallon and treats 300 gallons and an oxygen
scavenger, at about the same price per gallon...

http://dwdavies.com/water%5Ftreatment/

Hope you find this helpful.

Thanks. It was.

After talking with Modine and Farwest and Galvotec

http://www.farwestcorrosion.com/fwst...minco01.htm=20
http://www.galvotec.com/products.htm

this seems very empirical. A Galvotec engineer said they use about 5 mA/ft^2
(a lot) to protect steel in seawater, vs 2 in freshwater. They use more if
the water is flowing fast, as daestrom implied. The engineer didn't have
a value for aluminum.

The current can come from a sacrificial anode "battery" or a DC power supply.
The Farwest site has graphs to predict the lifetime of a pipeline-protection
anode as a function of soil conductivity. This seems to be a simple energy
calc. One of their products is 17 lb of magnesium inside conductive coke
inside bentonite clay inside a cotton bag, which disappears over time. This
can provide 1 amp for 1 year, ie about 1.7Vx1Ax8760h/17lb = 876 Wh/lb...

Galvotec said an anode wouldn't help much in this case (although there's
a 1996 patent for a radiator cap attached to a magnesium anode.) Modine
tried this unsuccessfully. Like chrome plating, it can protect the outside
of a tube, or the inside of a tank with a simple geometry, but it only
protects a few diameters into a tube. This seems to be a matter of water
conductivity and geometry. It might work if the deep insides of the radiator
tubes were directly connected to the anode and the parts closer to the water
hoses were connected via resistors with increasing values :-)

As to oxidation, an oil layer or oxygen getter may be useless if the radiator
is exposed to oxygen every day when it drains down to avoid freezing. STSS
EPDM-lined tank manufacturer Sven Tjernagel said "Don't use oil. That will
destroy the liner." He says just keep the water slightly alkaline. Modine says
their radiators should do fine if dielectrically isolated from other metals,
eg a bronze pump and a pressurized copper pipe DHW coil. The 12V radiator fan
could have an isolated DC supply. They say put a pan under the radiator and
make it inspectable and replaceable, in case it ever leaks.

Davies Chief Chemist Pat Fogerty recommends 0.5-2% of their "ACI 100" Al
corrosion inhibitor, listed in the "industrial" part of their web page.
A 5 gallon pail (0.5%) costs $41.80 + shipping and should last forever.

It's 42% sodium silicate, which may be essentially non-toxic when diluted.
It has a "2 mg/m^3" OSHA TLV (Threshold Limit Value) for human toxicity,
which seems to be a limit for the undiluted solution in a fog, vs a tank.
I wonder if it's still legal to preserve raw eggs in an undiluted solution.
Pat Fogerty says the MSDS says [the undiluted solution?] is non-toxic to
fish and has a "2,0,0" toxicity/flammability/corrosiveness safety rating...

Section P2902.5.2 of the 2006 ICC residential code for 1 and 2 family
dwellings says

Heat exchangers using an essentially toxic transfer fluid shall be
separated from the potable water by double-wall construction [unlike our
copper pipe coil.] An air gap open to the atmosphere shall be provided
between the two walls [which raises the cost and kills efficiency--
where's the GFX air gap?]

Section R202 defines an essentially toxic transfer fluid as

Soil, water, or graywater and fluids having a Gosselin rating of 2 or
more, including ethylene glycol, hydrocarbon oils, ammonia refrigerants
and hydrazine. [The scale runs from 2 (mildly-toxic, meaning 50% of 70 kg
humans would die if they drank 1 quart of it) to 6 (a few drops...)]

http://chem.sis.nlm.nih.gov/chemidpl...#_ToxicityData

If the "2" ACI rating is a Gosselin number for the undiluted solution,
the worst-case toxic dose would be 1 pint, and diluting to 1% makes
the toxic dose 100 pints, well over 1 quart, so it would be fine
with a single wall heat exchanger.

Nick

Is there some
corrosion inhibitor we can use at a low concentration?


purge the system of Oxygen with Nitrogen, then seal it?


if not, then go google on, and patent-search on, "deaerating feed
tanks". You probably don't have bleed steam on hand to run it with,
though.

On Aug 24, 1:46 pm, wrote:
I'm thinking about using a recent Taurus auto radiator or a Ford or GMC
pickup radiator


Is that because, as a mass-produced item, they're fairly cheap?

Maybe you're better off swapping a new radiator in, every XX years,
then installing another layer of complication.

Sell the old radiator to some junkyard. Scrap metal is worth a lot of
money nowadays.

Carbonates (CaCO3, Mg2CO3, et.al.) are not so bad.


The carbonates combine with the oxygen to form carbonic acid. At
your typical 900 F steam operation, it is a SEVERE headache. This is
why steam plants use active dearation to acheive 7 parts per billion
oxygen in the feedwater.

Yes. Active service naval ships use cathodic protection with zinc anodes
that have to be replaced every year or two.

I'm in active service in the Dept of the Navy as a shipriding Marine
Engineer. I live in a world where we pay a lot of attention to the
things that really could end up being showstoppers or inspection-
passing obstacles; and usually don't have any time left for the
theoretical niceties. I'm not qualified to discuss the theoretical
utility of active cathodic-protection systems; I can report that I've
never seen a Chief Engineer direct an underling to pay attention to
the cathodic protection system.

Magnetic Silencing seems to fall into the same category. I guess that
will change the first time the Iranians use a torpedo against us.

a single sailor can pull one up and replace it

change "sailor" to "mariner", if you're referring to a SS, an M/V, a
USNS, or one of the command ships (USS Mount Whitney, USS Blue Ridge).

The Ready Reserve ("mothball") Fleet is in the custody of the
Maritime Administration. Red & white stripes on the stack. Many were
activated for the recent show in Iraq.