DIY aquarium chiller

Hi all

I'm thinking of a DIY chiller for my saltwater aquarium. The current commercial chillers are far too expensive and inefficient for the same compressor HP rating. Here's some pics of the aquarium chiller I'm using

http://www.sgreefclub.com/forum/uplo...1083178174.jpg

The box on the left is the titanium heat exchanger ... its so small because of the high cost of titanium. This chiller is rated at 0.5HP

http://www.sgreefclub.com/forum/uplo...1083178078.jpg

I think the actual compressor rating is abt 1/4HP. My idea is if I build a chiller with a similar compressor but oversize the titanium exchanger and change the aluminium evaporator fins to copper fins, would that make the chiller more efficient?

What are the possible negative effects of oversizing?
Why would someone use aluminium for the evaporator fins when copper is a much better heat conductor?
What are the things to look out for?

Thanks alot! :)

do your fishes know you're such a cheapskate?? I'd be worried if I was them !!!

the cost of the chiller must be considered against the value of your fish.

it's not the cost of titainum,its the fact that plate heat exchangers are very efficient

each part is carefully selected to match-don't assume they use an xx compressor because they had some kicking about.

if you start swapping things expect the efficency to drop rather than improve
besides how have you measured the efficiency to know it is inefficient??


the fins are on the condenser

this is done because of cost -yes copper is more efficient but so is gold/silver etc

cheers

richard

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Originally Posted by BarraCuda

My idea is if I build a chiller with a similar compressor but oversize the titanium exchanger and change the aluminium evaporator fins to copper fins, would that make the chiller more efficient?

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No.

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What are the possible negative effects of oversizing?
?? Fishessucked in the HE perhaps?

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Why would someone use aluminium for the evaporator fins when copper is a much better heat conductor?
What are the things to look out for?

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Don't try to re-invent the wheel.

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Thanks alot! :)

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You're welcome.

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Originally Posted by rbartlett

it's not the cost of titainum,its the fact that plate heat exchangers are very efficient

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Someone actually opened up the Ti heat exchanger and found out that its nothing more except a few twist of Ti coil which is estimated to be less than 1.5ft of length. This chiller is rated to chill 400L of saltwater to min 25degrees celsius

Basically I'm not trying to be a cheapskate here but I'm wondering what can I do to make it more efficient. Aquarium chillers are often undersized and overpriced especially the china made chillers. I found out that a matching Ti heat exchanger for the compressor cost as much as what I paid for the entire chiller!

Thats why I'm interested to know more more about chillers and what components that can be overdesigned to ensure max efficiency.

I will be grateful if you can direct me to some easy to understand articles so that I can do more self reading. Thanks! :)

New user, so bear with me.
I know of a system used to keep seawater cool in a tank containing crayfish.Above a certain temp the crayfish get too aggressive and fight.
Condensing unit is a hermitique from memory,running on 409a,has TX valve.
Evaporator is a long length of copper tube inserted into a larger diameter plastic tube and the plastic tube is filled with vegatable oil.(A bit like a tube in tube condenser).When the evap comes out of the tank the plastic tubes are sealed.The length of this evap is quite long but you dont see it because it is hidden under the rocks and sand under the bottom of the tank.System works fine and does the required task quite well.There is another tank which has a titanium tube for an evaporator placed directly in the water.

Regards

This all sound very interesting to me.
I have recently taken a lot of interest in building a saltwater aquarium from scratch.
I have not done very much research as the thought has only been on my mind for about a month now.
With my backround in airconditioning and my interest in tank building, I can envisage a new career in the pipelines for myself.
If anybody reading this thread has any knowledge of the aquarium building game then any and all recomendations will be greatly appreciated!

Hi The system may already be efficient but if you want to chill your animals cooler for less dollars and a large tank its recommended to build your own.
Powder coated copper coils for the evap work as good as titanium as long its tripple coated white on black so no surface is left uncoated.
Use a discarded 2.5hp r22 wall aircon to drive your evap. Works bl00dy well as costs very little. defintely gives big bangs for your dollar.

First off copper ions = dead fish.

So you would need an all Ss Plate heat exchanger that is nickle brazed with zero copper coming into contact with the water! Or, you could use an Ss coil.

Using a Thermal static over a cap tube will net you some more efficiency but the system will need to be rebuilt a bit to include a receiver.

As for tanking building, say good bye to the skin on your knucles, never use the cheaper silicon, and have damned good insurance.

Hi all,
Aquarium chillers, well there is several options and like everything all depends on budget $$$$. If its only a small tank 1000Lt or less best option is one off the shelf different brands you pay for what you get can recommend aqua medics titan range bit exy $$$. If over 1000lt it is better to construct yourself but stay with the norm no shortcuts changing materials etc titanium heat exchangers are the only way to go. How much you spend on a chiller depends on what you intend to keep in the aquarium as well. Its a hard business salt water aquariums require alot of work but an interesting and rewarding one.

Cheers redhot

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Originally Posted by BarraCuda

Hi all

What are the possible negative effects of oversizing?

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It is a common belief that when the evaporator coil is oversized (increase in number of tubes) the cycle efficiency is increased, this is true if the refrigerant mass flow rate also increased. becuase simply:

Q = U A DT ........... Yes the increase in surface area (A) via the increase in number of tubes accounts obviously in an improvement in Q from this equation but it is disregarded that the increase in number of tubes leads also to a decrease in refrigerant average velocity and in turn, the overall heat transfer U is affected negatively and it can negate the increase in A. Nevertheless, the increase in flow rate is followed by an increase in compressor power and increase in back and head pressures. If anybody says, ok we can increase (A) by lengthening the tubes, the answer :it is ok provided the space has a permission for that but i complete it is not significant because the excess in frontal area necessitates the increase size of fan to cover the new area (if the coil Dx) and increases the evaporator pressure drop and of course causes a negtive performance.

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Originally Posted by BarraCuda

Why would someone use aluminium for the evaporator fins when copper is a much better heat conductor?

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Yes although the replacement of AL by CU will add a credit in the coil performance but it is rarely to find copper tube-copper fins compared with copper tube-AL fins; the reasons are:

As it is known the CU conductivity is 425 but for AL 205 the enhancement in conductivity will enhance fin efficiency and out of the headache of equations and maths; the enhancement in fin efficiency will be 36 % and accordingly the U and Q will be improved by the same magnitude (36%)...this is great but the problem with the CU is the weight because it density 8900 but for aL 2700, u will say to me my application is small, it does not matter and i reply i am talking about general case and also it does matter to replace AL by CU in this application, let me explain to u by energy bill to understand shortly what i mean:

The saving in energy bill (from AL to CU) = 2000 (operating hours)*0.36 (improvement)*0.2$kW/hr * HP*0.75

in ur application u mentioned 0.25 HP, so the saving 27 $ annually :eek:though the copper cost (US$1.76/kg) is expensive more AL (US$1.54/kg). however, the using of CU is more effective in large application with caution of the weight.

Cheers:)

I must say Mohamed, you do like your sums:D

I don't know anything about fish health and copper ions but aluminium and copper in contact with sea water = electrolysis.

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Originally Posted by expat

I must say Mohamed, you do like your sums:D

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Hi Expat

I have to say yes, it is nature of Job, I am a teaching assisstant in Faculty of Engineering and currently PhD student:D

Regards:)

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