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Joep Hogenhout
17-03-2004, 03:22 PM
Dear refrigeengineers,

A question.

I'm in lasershow business and when I have outdoor party's I use 1 or 2 1000 liter water containers to cool the lasersystem.

When I use 1 1000 liter container that water is in about 1 till 2 hour 30\40 degrees celsius when I drive the laser with DC 30A secondary current. The laser needs water with a maximum temperature of 30 degrees celsius, and 8.5 liters/min or 2.2 gal/min

Is there a way to cool the water down to about 10 degrees stable? Please keep in mind that the laser must be able to run the whole night.

If it is possible to cool down such containers, maybe it's also possible to look for a smaller solution as the 1 by 1 meter 1000 liter containers, because then I not need such big vehicle to move the containers. The cooling device must cool alot quicker when I use a smaller container instead of a 1000 liter one.

Thanks

chemi-cool
17-03-2004, 05:39 PM
hi joep,

the laser machines I know are for cutting,
each one comes with a small chiller to keep the water cool without a reservoir.

I think it will be easier for you to carry a small chiller instead of a 1000 litre tank the water ca go down to 23C, under that temperature you might get condensation and you dont want it.

so if you tell me in what temp. the water are coming out.
I can tell you the size that you need.

this way you will not need any container.

chemi

Peter_1
17-03-2004, 06:57 PM
Originally posted by Joep Hogenhout
When I use 1 1000 liter container that water is in about 1 till 2 hour 30\40 degrees celsius when I drive the laser with DC 30A secondary current. The laser needs water with a maximum temperature of 30 degrees celsius, and 8.5 liters/min or 2.2 gal/min

Is there a way to cool the water down to about 10 degrees stable? Please keep in mind that the laser must be able to run the whole night.

Worst situation, 1000 liter was heated in hour from 10 to 40C.
So you need a cooler of 1000 x 30 x 1,16 = 34 kW.
MOost positive situation : 1000 l in 2 hour from 15 to 30C =
1000 *0.5 x 15 x 1.16 = +/- 8 kW.

So your figures should be more precise to calculate your machine.

I should go for this configuration for a Rhoss (relative cheap and good quality, everything build into it, pump, buffer, made to install outside..) of +/- 15 kW.

You can also consider to install 2 independent machines so that you will have a safer setup. If one fails, then you always have the other one as a backup.

You will need +/- 20 to 25 l/kW so 500 l should be sufficient.

chemi-cool
17-03-2004, 08:12 PM
peter,

he just wants to cool the laser head and you give him too much,
mixing valves and thermostates.

why not a chiller as you advised about 20KW and connect it straight to the laser?

MTK also make that kind of small chillers.

chemi

Peter_1
17-03-2004, 10:02 PM
Originally posted by chemi-cool
he just wants to cool the laser head and you give him too much, mixing valves and thermostates.
Why not a chiller as you advised about 20KW and connect it straight to the laser?



Agree Chemi, will edit my previous post.

chemi-cool
18-03-2004, 05:52 AM
good idea marc,


since lasers work at nights and the ambients fall down any way,

to be safe, I would add a chiller as backup.


chemi

Peter_1
18-03-2004, 06:52 AM
Hmmm,...Holland same weather as here.
If you need water of 10C, then at least ambient of 5C. Get never that cold, except for some months during winter.

DaBit
18-03-2004, 09:48 AM
Mr. Hogenhout, I see you live in The Netherlands. I cannot help you, but I know a company/person who is very capable of helping you with this problem. You know, one of those belonging to the top 5% of their trade. If you need contact information, send me a private message or an E-mail.

Joep Hogenhout
18-03-2004, 02:01 PM
I would like the cheapest solution, because I've invested a lot of money in the laserdevices.

I like to make it myself, that's no problem.

Maybe I can make a bigger heat exchanger then on: http://www.icecoldcomputing.com/text/show_page.php?id=23

With a phase change setup from a big refrigerator.

Can I change the cooling part in the refrigerator with the self made heat exchanger without problems?

Peter_1
18-03-2004, 04:22 PM
Originally posted by Joep Hogenhout
I would like the cheapest solution, because I've invested a lot of money in the laserdevices.
Cheapest or best? Think the chiller will cost a fraction of your lasers.
You have to make the choice: don't do anything or install a DIY cooler like you described and destroy your lasers or do it the way it has to be done, with other words,... like a pro.


I like to make it myself, that's no problem.

Maybe I can make a bigger heat exchanger then on: http://www.icecoldcomputing.com/text/show_page.php?id=23

With a phase change setup from a big refrigerator.



Can I change the cooling part in the refrigerator with the self made heat exchanger without problems?
Which self made exchanger?
No, you can't.
Seems that with this suggestion you don't have a clue how those systems work.

Joep Hogenhout
18-03-2004, 04:42 PM
Yes indeed, I don't know how it exacly works.

I can run a whole night, but then I must turn the laser on and off every time I've performed a show.

This is only an option but I not want to spend a lot of money to it.

I want to make a system that I can use @ the water out of my power supply. From there comes out the warm water.

That has to be cooled.

I love to make things by myself, but I haven't got any experience with this sort of cooling stuff

DaBit
18-03-2004, 05:18 PM
Originally posted by Joep Hogenhout
I would like the cheapest solution, because I've invested a lot of money in the laserdevices.

Isn't that a good reason to use a decent cooling device?


I like to make it myself, that's no problem.

That is harder than you think...


Maybe I can make a bigger heat exchanger then on: http://www.icecoldcomputing.com/text/show_page.php?id=23

With a phase change setup from a big refrigerator.

A 'big refrigerator' does about 300W at best (to keep it simple). Compare this to the amount of power you feed into your laser power supply. The heat must go somewhere, and 99% ends up into the cooling water.


Can I change the cooling part in the refrigerator with the self made heat exchanger without problems?

Sure, if you scale up everything 1000x, it would maybe work. Maybe not.

Start by telling us how much heat you need to get rid of.

If you intend to go the DIY route, I would suggest to add one or more car radiators with large fans on them. This would make a difference, but I don't know how much. On the other hand, it's cheap to try.
Maybe adding a car

frank
18-03-2004, 08:14 PM
What sort of car Da Bit????? :D :D

frank
18-03-2004, 09:00 PM
Hi Joep

As the guys have said, yes it is possible to achieve cooling to your equipment without having to lug 2 x 1000 litre tubs of water around but everything has a price. The tubs of water act as a passive heat sink so as your lasers heat up the excess heat energy is transfered to the water (or heat sink) and is dissapated, which allows your lasers to keep on working.

From what you say, it looks like the 1000litre or 1000kg of water rises in temperature about 10deg C per hour. This equates to about 12kw of heat load. You can of course buy refrigeration equipment which will handle this load but are you prepared to invest? Only you know the answer. We of course can offer (collectively) the best solution to your dilema but you need to advise us which way to go. Balls in your court mate - as they say! :)

shogun7
19-03-2004, 01:26 AM
This may be of some value to you!
http://teryx.bobdbob.com/~protius/lasercooling/
Roger

DaBit
19-03-2004, 09:18 AM
Originally posted by frank
What sort of car Da Bit????? :D :D

Uh, oops :)

But to elaborate on the car radiator idea: Just use what you can get for free/cheap. It is probably not good enough to keep the water temperature below the 30 degrees on every circumstance, but it could work.

And why does the topic starter want 10C water? It seems to me that 20C or 25C water would be sufficient too.



This may be of some value to you!
http://teryx.bobdbob.com/~protius/lasercooling/
Roger


That's about cooling a small (100mW or so) argon-ion laser head. I expect the topic starter to use more colorful kryton-ion laser tubes.

Peter_1
19-03-2004, 09:26 AM
14 kW chiller will cost +/- 2.000 Euro.

Or make a small adiabatic cooler wit he the car radiators from Dabit and spray some of the water you use for your circuit in the radiator with fuel nozzles (For example Danfoss) they use in ordinary fuel burners.

I did this to cool down some years ago a huge space where a friend of mine had +/- 10.000 rabbits were inside and due to the heat of that summer, one after the other got a heard attack (the rabbits :)).

Joep Hogenhout
19-03-2004, 12:42 PM
It's a 6 watt argon laser I use.

The temperature of the water that goes in the tube may not exceed the 30oC (86oF).

But I better can keep the water about the 10 till 15 degrees just for safety. 20 is also possible. but that is a little bit to high tolerance.

DaBit
19-03-2004, 02:14 PM
If I recall correctly, a 6W Ar-ion laser tube needs about 280VDC @ 35 amps max.

Thus, power input is about 10kW max (of which 6W is light output).

At 30 amps and ~260VDC it's about 7.8kW.

power supply produces another ~2kW, if it is also watercooled.

Thus, 12kW cooling load is a good guess.

At 8.5 liters/min coolant flow, which is 0.142 l/sec, the exit temperature of the water would be 12000 / (0.142*4200) = ~20C warmer than the inlet.

If we have a 20C ambient (not unusual in The Netherlands in the summer at night), and use 25C water at the inlet, we have 45C water at the inlet of the car radiators. At this inlet temperature and with decent airflow they can reject quite a lot of heat.

A 100pk car engine under full load also dumps ~25kW of heat into the coolant which is rejected by the car radiator, though at a much higher temperature.

A very rough guesstimate: with 4-6 car radiators (from 100pk cars :) ) and adequate airflow you should be able to keep your liquid cool enough.

How would I build such a system? I'd make a box of flightcase wood, mount the car radiators on the sides of the box, and use a few powerful fans sucking air through the radiators mounted in the remaining sides of the box. The water pump can be inside the box as well.

I don't see why you would want water cooler than 20C. The purpose of the water cooling is to prevent the laser from overheating, and I don't see how cooler water would prolong the tube life. Even worse: too cold water causes condensation/sweating which can't be good for the tube.
Your optics are the weakest points in such a laser.

chemi-cool
19-03-2004, 02:48 PM
hi dabit,

earier on this thread I have warned joep about condensation. its fatal for lasers.

I maintain a foctory that uses big lasers for cutting metals.

you do not need a big chiller, and if you use a dry cooler, it can all be on a trailer and the chiller can only used as a backup.

chemi

Joep Hogenhout
19-03-2004, 04:48 PM
But DaBit,

Can't I use the heat exchanger that you've build on your website in combination with a cooling installation of a big refrigerator?

Then I can fill the heat exchanger spiral with coolant that also is in the refrigerator system. The water out of the power supply I can point through the evaporator housing.


I mostly run the laser on a standard water outlet in discotheques, there is the temperature also about 10 degrees. I've never had any troubles with condensation.

And when, the tube and optics can handle it, because the optics are protected with an airtight cover over the brewsters.

Only the powersupply could be damaged by it, because the transistors from the passbank become wet.

frank
19-03-2004, 06:04 PM
Thus, 12kW cooling load is a good guess.

A good guess! the calculation brought it out at 11.63888kw so I rounded it up to 12kw ;)

Joep Hogenhout
19-03-2004, 08:10 PM
Nice picture frank ;)

DaBit
19-03-2004, 10:37 PM
Originally posted by Joep Hogenhout
[B]But DaBit,

Can't I use the heat exchanger that you've build on your website in combination with a cooling installation of a big refrigerator?

Sure, if you exchange the 'big refrigerator' with a unit which is many times more powerful (let's say about 3 A/C outdoor units as seen on shops and office buildings), and my heat exchanger on steroids.


Then I can fill the heat exchanger spiral with coolant that also is in the refrigerator system. The water out of the power supply I can point through the evaporator housing.

The basic idea is OK :)
If you want a more thorough understanding of how a refrigeration system works, I suggest www.refrigerationbasics.com


Only the powersupply could be damaged by it, because the transistors from the passbank become wet.

At 10C the risk is not so high due to the temperature difference between the silicon and heatsink. But it's critical, especially in damp discotheques (I've been doing drive-in for years).

Anyway, you really seem inclined to go the DIY-route. If I can do so, so can you. It's just a larger scale.

Make sure that you understand how refrigeration works. That will help.

BTW: I sent you a PM about the guy I was talking about.

RogGoetsch
20-03-2004, 07:11 AM
Designed a laser cooling system a few years ago. Laser was for cutting. Laser manual provided water temp & flow rate specifications. Installed a cooling tower and a three-way valve to prevent temperature from dropping too low at low ambients.

Laser was aimed using small mirrors, computer controlled, each with a heat sink on the back with a channel bored for coolant circulation. Water temp had to stay above dew point to prevent condensation on the mirrors.

Saved the customer a bit of money, using an open-loop cooling tower, but due to the water treatment hassles, he bought a chiller with his next laser.

Rog

Sridhar1312
19-04-2009, 07:43 AM
you can have tank &coil with condensing unit attached to cool the water which will work out simple r and simple

MIT
19-04-2009, 09:28 AM
you can have tank &coil with condensing unit attached to cool the water which will work out simple r and simple


i think this will work we have tried like this set up in a shampoo manufacturing. although you really need to invest on the equipment

Peter_1
19-04-2009, 09:33 AM
This thread is standing up out of his grave :D

Magoo
20-04-2009, 11:25 PM
Well said Pete 1, like a pheonix rising out of the ashes 5 years later. The original poster has probably retired by now. Short of reading all posts, did any suggest throwing some ice in the tank, would be quick and cheap ?.

MIT
21-04-2009, 01:27 AM
hahaha sorry i'm new hir i didn't notice it was dated 2004 i just reply on the last quote which is 2009. really sorry :confused: