Looking for an old fan assisted radiator or two to loose some heat from a piece of equipment, so if anyone is pulling any out get in touch to convert them to cash. Don't need to be cosmetically pretty but do need to work.
(I need to loose 17 Kw at 40C max at 3 atmospheres (45 psi))
Email address needs de-spamming in the obvious way.
AWEM
Breaker's yard, car radiators. Certainly qualifies on the 'not-pretty' aspect.
pretty
'not-pretty'
But I doubt they will stand 45 psi. Most rad caps are 7-10 psi so even with a 4 times safety margin are under rated
AWEM
Any neighbours got a swimming pool?
message
pretty
Sadly not, but one of them did suggest that solution this afternoon ! The heat lose will only be for about 15 minutes every month or so.
AWEM
Sounds OK.. a big tank of water. About 400l should be enough to give about a 15 degree rise, I think.
Would they stand 3 bar? I doubt it.
Could you not use an indirect heating cylinder in reverse?
Some sort of liquid thermal store sounds plausable since it is only for a short duration...
Sounds like a tiny version of a dummy load that I saw running in one of the Marconi rig rooms once: They had a very high power HF transmitter (1MW!) with a saline cooled dummy load in place of the transmit aerial. This was piped for a few hundred feed throught the building into the carpark, where there was a bank of about 4 blowers (each about half the size of a car), that would blow away the unwanted heat!
pretty
...mmm I had initially thought about that but working on a 205 litre drum of water if my maths is right it will heat it up 180 degrees C in
15 mins (!!) but I'd love to be proved wrong.17Kw for 15 mins and the temperature must not exceed 40 deg C how big a volume of water is needed if we assume 20 deg C initial temp?
AWEM
OK
SHC (Specific Heat Capacity) of water = 4183 J/kg/K
You are going to supply 17000 * 15 * 60 = 15.3 MJ
So, mass required = 15.3E6/4183/(40-20) = 183kg, so about 183 litres.
Or in real units, approx 35 gallons. Seems about right.
Cheers
Tim
Should be able to take 3 bar OK, many mains taps are well over that.
Thanks for that Tim, I got my units wrong somewhere along the line
AWEM
You say 45psi...
Problem - getting a water-to-air h/ex that handles it o Car Radiator
---- coolant side -- 15psi usage, often limited by plastic end tanks
---- ATX gearbox side -- 5-45psi, but very small in size o Car Oil Cooler
---- Mocal/Earl -- 90-100psi usage re startup in cold weather
---- problem is they are very small or expensive if large
Solution - combine water-to-air h/ex with large tank o Open tank removes the pressure
---- feed the tank with the output of the radiator
---- feed the return-line with the output of the tank o Car Radiator only sees low pressure
---- as long as the radiator can flow sufficiently
---- at low flow there is no backpressure, at high flow there is backpressure
If the radiator can not, you simply use a separate loop & pump for that.
Radiator selection... o Car
---- plastic-end-tanks or all-metal
---- single row, double row or triple row
---- clogged to hell, leaking or clean o Truck
---- 48"x48" in triple row or Tonka Toy sized if you feel like it
Cooling fans... o Trucks use 4800cfm 24V, typically 2-4 -- very large PSU required
---- they run more often due to limited vehicle speed
---- hence the much larger radiators & multi-core radiators o Cars use single 12A 12V, or twin 12-21A 12V if air-con-&-atx fitted
---- car radiator fans create airflow when vehicle is moving slowly
Don't overrate car radiators... o Car radiators do reject 40kW+ at 120mph+
---- that is not by fans, but the 120mph+ airflow over them :-) o Car radiators work on a high temp delta of 85-105oC water v 30oC air
---- your application is at lower temps with a low temp delta
A water tank inline offers... o Solves the pressure problem - by virtue of being an open tank o Provides a margin of safety - if you DO get a big leak
17kW sounds quite a lot, but it's quite low compared to HVAC rejection.Re quantity of water, realise 1m cube is quite small - yet 1,000 litres. o No idea if the sliding lid polypropylene shutter trucks will hold water o I suspect they hold about 4m cube - but may buckle under 4 tons :-)
fitted
rejection.
Dorothy,
Thank you for that comprehensive, reasoned and detailed reply - I've printed it out for investigation!
My thoughts at the moment are to possibly use a copper c/h tank as a thermal reserve, pumping the coolant through the primary coil which should have no problem with the pressure, and has the advantage of keeping the primary volume low. The primary circuit will have to be doped 20% with mono-ethyl-glycol I'm told if I find a source of the stuff (not normal anti-freeze) Then the copper cylinder bulk water can be circulated at lower pressure through a fan radiator. Trouble is it's all getting a tad complex and threatens to take up too much space, hence originally looking for a direct water to air solution.
AWEM
I'm intrigued as to what requires 17kW to dumped in 15mins but only once a month or so...
An ordinary "fast recovery" HW cylinder should be able to cope with that heat input and if you get a tank big enough you might not need to artifically cool it or if you do why not make use of it heating you DHW or augmenting the space heating in the winter. Energy is energy...
The message from "Dave Liquorice" contains these words:
That's quite a bit! 68kW but only sometimes....a thing that grabs trucks as they pass and slows them down a bit?
which
snipped-for-privacy@howhill.com
Dave,
It's an induction melting furnace, 100Kw input power, with forced liquid cooling to the melting coil and semiconductor drivers running at 83% efficiency hence 17Kw into the water. Oh and I won't be using it that often hence 'once a month'
AWEM
I would have thought so myself. Very few plumbing fixtures can't stand 3 bar (mostly thin walled copper cylinders and the like). I suspect it would work, provided care was taken to avoid the consequences of failure.
Christian.
Hi,
Your best bet might be to find a local company that refits commercial air conditioning, they might have an old working evaporator or two that you could have for a reasonable sum, maybe not much over scrap value.
These will take well over 3 bar and should have a rating plate stating the output as xx delta °C at yy kW so you can work out roughly how much kW it will dissipate for a given flow and return temp.
The connections should be at least 1/2" which will allow a flow to take away 17kW easily.
Try posting on , they should be able to give more info and some idea of costs.
cheers, Pete.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.