Car radiator gives poor heat exchange

[Mr Sippy]

I used to run water through my condenser from tap to waste. Used 25-30 gal water per run. The water came out at a fast trickle around 130-140F

Recently I was given fan/radiator from '05 Chevy Malibu. Coupled with a pump and reservoir I thought it would make for good recirculating cooling not dissimilar from what I see others have put together.

First I set it up like it was in the car; fan pulling air through the radiator. Coolant output temps got hot pretty quick and I shut down. Then reversed the fan to push air and put a little separation between fan and radiator. Not much difference.

Some particulars: 5500 watt element at 100% in a well insulated boiler. The pump is returning approx 6 qts/min. The 2 speed fan (2 motors) is powerful. In the car it was on a 25A circuit. Putting my hand in front I'd guess over 300 cfm. That's using a 150 cfm fart fan as a reference. The coolant out temps rose to about 150F in 13 minutes before I shut down. I didn't get the sense it would level off. The temp differential between in and out was steady. The temps were monitored with rtd sensors.

So I guess I am wondering: For those using similar setups; do yours run that hot? Do they plateau eventually? Water and air flow seem to move plenty good. Unless I'm missing something a car radiator just doesn't seem adequate for 5000+ watts of power. Thanks

[HDNB]

i just installed a 3 core aluminium rad with a dual fan (ebay, 175 bucks) for a gen 2 camaro as an intercooler to pre-cool the water return to recirc tank. 500w 12v LED driver power supply (amazon 50 bucks) to drive the dual fans.
it works friggin awesome.
i don't have hard data, but it takes hot water and makes it slightly warm at 15*C ambient.
it's 20 below here now and the water comes back cold now.

i just bought a new IR t-meter so i can get some actual numbers on the next run maybe sunday or monday

[Fart Vader]

it's 20 below here now and the water comes back cold now.

Jesus man, 20 below! WTF, Frozen North is an understatement. It's only zero C in my part of town.

[Mr Sippy]

Well, there's car radiators and then there's car radiators. Point taken.

Maybe from the folks using junker radiators...?

[HDNB]

it's 20 below here now and the water comes back cold now.

Jesus man, 20 below! WTF, Frozen North is an understatement. It's only zero C in my part of town.

you in a differnt part of town. warmed up to -15 currently but yeah it was -23 when i was stillin' night before last.

[hpby98]

I run five 5-foot lengths of baseboard heater with fans, and it helps knock down my 4400 watt runs

I run a much smaller 1.5 x 1.5 foot rad with a couple 12v fans when I reflux and it matches with my 1100 watt input

[Mr Sippy]

I run a much smaller 1.5 x 1.5 foot rad with a couple 12v fans when I reflux and it matches with my 1100 watt input

That's pretty close to my size. And clearly now, I believe, undersized. Thanks!

i just installed a 3 core aluminium rad with a dual fan (ebay, 175 bucks) for a gen 2 camaro as an intercooler to pre-cool the water return to recirc tank.

How big is the recirc tank? Big enough to buffer temp change? My tank has no capacity, really only keeps air out of the system. How did you come to choose that particular radiator? Maybe a few specifics on your setup. I wouldn't choke on spending $175. Especially if it works. Thanks.

[hpby98]

it's 20 below here now and the water comes back cold now.

Jesus man, 20 below! WTF, Frozen North is an understatement. It's only zero C in my part of town.

Yep, I ran mine in the cold and stopped pumping coolant between strips while it was -25 out. Froze in minutes...

[HDNB]

How big is the recirc tank? Big enough to buffer temp change? My tank has no capacity, really only keeps air out of the system. How did you come to choose that particular radiator? Maybe a few specifics on your setup. I wouldn't choke on spending $175. Especially if it works. Thanks.

really big. it gets hot without the rad, but not at all with it. i chose 3 core aluminum because two core doesn't work worth shit in a car, but 3 core will cool a 350 on a smokin hot day no problem. plus i own a gen 2 camaro so spare parts is good and gen 2 is really popular so parts are cheap as guts.

i have 3/4 inch feeding 1/2 inch irrigation on the deflag and PC and then they are teed back together after the condesors into a 3/4 inch hot water garden hose out to the radiator, then outta the rad back to the tank. the system is pumped by a constabt pressure 60PSI "bump pump" that is designed to hold a constant 60psi , bumping up the pressure on a well pressure tank system.

[Mr Sippy]

Thanks HDNB. Nice setup

Considering that and hpby98's 25 feet of hydronics to help knock down 4400 watt; a big reservoir is a necessary part of a closed cooling system- at least with a car radiator. My boiler is well insulated and that doesn't help. At 450 sq in kinda figured the radiator was 'light' but hoped the fan would make a difference. Back to the drawing board.

Cheers.

[HDNB]

at start p this AM, the water is at 18*C the ambient air temp outside is -3*C. the radiator strips off 9*C, returning at 9*C.

i'll report back in a while once the heat differential is bigger. see how it does.

[DetroitDIY]

I'm running a 3 core I junk picked from some industrial refrigeration trash, with a powerful house fan blowing onto it about 10" away. No shroud from fan to radiator yet. 1/2" lines to a from it. 1300 gph sump pump. 40 gallon reservoir. 5.5 kW system, but mostly running about 2 - 2.5 kW.

Delta T from radiator is about 6.5 F at 2 kW, 9-10 F at 3 kW.

This works pretty well for 11-13 gallon runs on my 4" flute that last somewhere in the range of 5 hours. I do a run a trickle of garden hose water to it and drain the same from the reservoir about 3 hrs into a run to hold the T steady. Reservoir temps are 70 - 75 once the system (and the 400 sq. ft. shop I'm in) heats up.

I did a decent job cleaning the caked on grim off the fins when I first received it. Straightened some fins, but have bent others in the process of setting it up. Hoping that once I fix that and properly shroud it, I won't need any garden hose in the winter.

[hpby98]

Thanks HDNB. Nice setup

Considering that and hpby98's 25 feet of hydronics to help knock down 4400 watt; a big reservoir is a necessary part of a closed cooling system- at least with a car radiator. My boiler is well insulated and that doesn't help. At 450 sq in kinda figured the radiator was 'light' but hoped the fan would make a difference. Back to the drawing board.

Cheers.

They are stacked vertically, which allows fans to blow across them all

Helps keep the water below 50°C though.

[HDNB]

The exit water is 106f and post- radiator the temp is 83f

My fans are mounted directly to the radiator. I think if you'r fans are blowing from feet away are doing little if anything.

mebbe try sucking air through it like on a car.

[Mr Sippy]

Delta T from radiator is about 6.5 F at 2 kW, 9-10 F at 3 kW.

The exit water is 106f and post- radiator the temp is 83f

My deltaT is also about 20-23F at 5000+W. Even when output temps creep up to red line, the deltaT stays steady. Only tried to cool a strip (full power) so far.

Thanks for the replies. I think your setups (and mine) remove heat at a similar order of magnitude. I can see now that cooling (the condensing water) thru a typical size radiator also requires sufficient heat storage via reservoir. Now I wonder how much reserve water it takes to void the need for active cooling.

Maybe time to mess around with those Q=MCDeltaT equations

Cheers

edit: HDNB- I had the fans oriented both ways. Made no difference

[HDNB]

mine picked up a few more degrees cooling when the output temperature went up.

if you have limited water try choking back the water output on the still to 130 exit temp. That way the the heat strip will be bigger, leaving the reservoir cooler longer. (i think)

[DetroitDIY]

mine picked up a few more degrees cooling when the output temperature went up.

Right, the greater the temperature difference of your cooling water to the air cooling it, the more effective it should be... but your average temp will be running hotter. So it may just depend on how hot you're OK running your coolant water at, and striving to run about that temp, or a bit lower.

[Bearpig]

I'm curious as to what some of you are paying for a cubic meter of water (1000 liters)?
Around here it's around $1.50/cubic meter if it doesn't include sewage fees (around $4 if it does, but I have my own septic tank).
Last time a 12gal run with a 5000w propane burner and tap water just trickling through a copper liebig condenser I used around 200-250l of water, so around 37 cents of water.

I'm trying to think of a way to justify buying radiators and running fans, peltiers, refrigeration, etc when water is so cheap. A $175 radiator and dual electric (I'm guessing a few hundred watt) fans running constantly would be hard to justify, I'd never make that money back on the water savings.

The first thing I did when putting together my still is instinctively start trying to figure out a way to reduce/recycle water usage and increase efficienc, because running water nonstop from the tap seemed like such a waste.. but some of these solutions seem much more expensive to run than just letting water flow from the tap (especially if you can make use of that water later to water your garden). Are people looking for radiator/peltier/etc solutions primarily doing it for the challenge and DIY engineering aspect, or am I really missing something here?

Really the only way I could run it cheaper is if I run the coolant output into a barrel which I leave out to cool overnight, then use a 10W aquarium pump to recirculate it for the next run.. then I'm using 0.1 kw/h of electricity instead of 1/4 cubic meter of water, but even then we're talking pennies of savings.

[ShineRunner]

I didn’t really spend much on mine. I used the radiator out of my truck, which spring a small leak. It only leaks under pressure, so it’s fine for this application. I used a cheap box fan that I had laying around and used a cargo strap to hold it together. I got a cheap eBay pump wired to an old cpu power supply. The most expensive thing is probably the quick connect fittings, honestly.

It knocks down 5500w with the fan on full blast. My product outlet is usually about 105-110 degrees on full power. Since I’m indoors, as the indoors temp rises, the cooling power decreases, so I occasionally have to open the window to cool it off. I run in the winter time. I reuse 3/4-1 gallon over and over.

I hate wasting water. It’s not just about the cost. But that’s me.

SR

[Bearpig]

I try not to waste water either. When I first started distilling I was freaking out at the thought of leaving the water running for 10+ hours straight, but in the end it really only adds up to a bathtub full of water.

I'm usually cooking at the cabin, so the outflow goes into a 400l wine vat, which then gets used as a hottub by me and the gf, then I use it to water my grapes

[DetroitDIY]

I didn't look at the cost, but I'm on municipal water so I'm sure mine is more than your $0.37. If/when I can ever find my water bill, I'll figure it out.

I junk picked my radiator, and it had a fan with it, but I need to get that part of it rigged up properly yet. In the meantime I'm running it off an old POS fan that I've had. Couple valves to allow bypass or not and some time is all it cost me.

I'm definitely keen on the environmental aspect, wasting water just seems a shame if you can avoid it. Plus I definitely enjoy the process of making things.

[Bearpig]

The thought of cooling by recirculating rainwater from a reservoir with a solar/battery powered aquarium pump has crossed my mind.. the amount of money it would save compared to propane/ingredient costs would be pretty insignificant but the idea appeals to me.

How many runs are you guys doing at a time?
If you run a typical hobby still all day it shouldn't use more than 400-500l of water.. which will cool back down on its own overnight.
Or is the space an issue?

[DetroitDIY]

I'll run typically an 11-12 gallon wash. I run a flute, typically one and done. And may add some feints, or may not. I heat for ~30 min at 5.5 kW, then back off to about 2 kW, and will eventually creep up to 3 - 3.5 kW over the course of 3-4 more hours. So, usually a 4-4.5 hr run, averaging maybe 3 - 3.2 kW over the 4-ish hours. I cool with 40 gallons (~150 l?) of water. I keep the reservoir temp pretty cool, generally no higher than mid 70's F. To do that, I often end up adding a trickle of cool water from the garden hose and allowing a bit of the reservoir water to drain at a similar rate. I may be able to run hotter (ran with reservoir temps up to 115 F when I was running a pot still), but just haven't done that yet with the flute.

I'm generally 1 run at a time. 8 hrs running the still is just too much for me. Space is an issue for me, but if I had a big tote for my coolant reservoir, I would definitely be all set. Or if I just let the water get hotter. Or if I improve my radiator cooling system a bit. I do not generally keep my 40 gallons of water from one run to the next. It gets a bit dirty (especially as it was flushing out the radiator core), and I like to use it as a massive rinse tub for things along the way. Just seems to get a little funky if I don't drain it. But that would definitely be an environmental improvement.