I want to make a pump, which gives me cold liquids at the end. But i dont want to cool the bottle where the liquid comes from. So i thought about using a Peltier Element and lay the tube over the cold site so the liquid will be cooled before dispensing.
Could that work? Do you have another suggetions how to do that? 
Thank you
That could work but it depends on how hot the liquid is, how cold you want to make it, the flow rate and the actual area that is being cooled.
Okay. i think about a standard 5v pump, so not very fast.
And it is room temperature i think so not very hot.
What would you use? Do you have other suggestions?
Yes, I'd use a Peltier
there is 2 major ways to "create" cold in commercial devices:
the main one is a gaz compressor (like in fidge and freezer) and the main purpose is to MAINTAIN a cold environment. So it usually need as a good insulation as a constant power.
the second one is Peltier element. Theorically, this module rocks. Pratically, it has a low power output (compare to gaz compressor) and so can handle little volume at the same time.
To use it, you need to put the Peltier near the hose as it will cold the liquid just before to leave the circuit. It eliminates the need of insulation (to keep aside a volume of cold water) and the module need to be powered only when withdrawal the liquid.
As an example, I used Peltier in PCR device (molecular biology) and the performance was really stunning (go to 25°C to 80°C in few minutes, then go back to 25°C) BUT the volume of liquid was really small (like a dozen of milliliters).
If you have datasheet for a specific Peltier module, get the max power output (in watt), so you can convert it in "how many degrees I can lower in how many milliliters in how many time". This is feasability and may give you a good approximation of the result.
EDIT: not the question itself, but.... to get fresh water is usually a modern man need. Take care with the material you use in contact with your liquid!
I doubt it, because you will not be able to supply enough cooling from even a very large Peltier device.
You might have to reduce the flow to a very small dribble.
Okay. So what would you suggest?
OK, but I think it's too loud and too much effort for me.
Yes, I thought I could lay the pipe in an S-shape around the element so that it has a longer time on the element.
You can buy liquid coolers like they use for cooling big microprocessors.
Save you some time with the mechanical set-up
Yes, I have thought about that, but I think it would be much more expensive than doing it myself with a tube over a peltier element.
Of course and it will be more fun to do it yourself
Hi,
First question;
What temperature do you want to cool too?
Second question;
What is the liquid?
Thanks.. Tom.. 
Peltier fluid cooling at DuckDuckGo
It has been 45+ years since I took thermodynamics, but I'll sum up what several have stated: the volume of liquid inside the tube that is in direct contact with the cold-size will be the maximum volume that you may dispense at a single time (quickly.) If you are thinking about using neoprene (human safe) tubing, then you have to deal with a large delta-t to cool the liquid inside the tubing.
You could resort to residential copper water pipe or copper tubing used for supplying water to kitchen appliances, but you are going to need a very good thermal conducting surface for the tubing to mate with the cold-side of the peltier.
Some youtube stuff:
Peltier fluid cooling at DuckDuckGo
Personally, I'd buy one of the mini-refrigerators just big enough for a six-pack and put my fluid tank in that enclosure.
When 'in doubt', always assume beer 
I would forget about a tube over a Peltier, for decent heat transfer you will need to have a small tank in intimate contact with the complete peltier device.
You will need a heatsink on the hot side of the peltier, with a fan if needed.
You will not only need to monitor the fluid temperature, but the two peltier surface temperatures to avoid destroying the peltier device.
Your fluid volume rate will also influence how cool you get your fluid.
Tom...
A more complicated method, run the tube for the fluid inside of a slightly larger tube through which you are circulating another cooled fluid (water) that is recirculating from a tank that is cooled by the peltier. The two concentric tubes can be coiled to give a longer tube and therefore a larger surface area. Basic idea is a heat exchanger.
< edit >
Simpler would be just to coil the fluid tube inside the tank.
About < 10°C
Most of the time it will be used for alcohol, I think. ^^
Do you think this is really necessary?
I know, there i will use a old cpu cooler with a little fan.
Yeah i know...
That would also be an option. But then I would have to cool a tank all the time... in the other solution I only have to switch on the cooling when there is liquid being dispensed. Or do I have other advantages in your idea?
