The cooling unit

In this article I am going to speak to you about the part hardware of the cooling system. To have a good yield on cooling it is essential to have good component otherwise this one can fall …

1. General operation

The goal is to have a simple system to operate on a daily basis and to maintain. For this I use a tray in which there is a liquid cooled with Peltier modules through a waterblock. In this liquid, dip copper coils in which the various drinks will circulate, as in a beer printer.

2. Presentation of the different components

2.1 The DS18B20 temperature sensors and operation of the 1-wire bus

"The 1-Wire bus is a bus designed by Dallas Semiconductor.The voltage level used on this bus is 3V or + 5V.This bus supports a series, parallel or star topology. And works according to the master / slave principle.



Generally used for temperature measurements, there is a full range of compatible components.Each component has a unique physical address, engraved in the chip during manufacture. This is one of the reasons for Dallas's reluctance to allow the creation of 1-wire slave other than the ones it produces: mastering the identification of bus slaves. "
http://www.planete-domotique.com/blog/2009/06/20/le-bus-1-wire/

The temperature sensors used for the regulation of the cold part are DS18B20.

2.2 The Peltier module

"The Peltier effect is a thermoelectric effect consisting of a physical phenomenon of heat displacement in the presence of an electric current. The effect occurs in conductive materials of different natures linked by junctions (contacts). One of the junctions then cools slightly, while the other heats up. This effect was discovered in 1834 by physicist Jean-Charles Peltier."

https://fr.wikipedia.org/wiki/Effet_Peltier

The advantage of these modules is that they are very cumbersome (3mm thick 40X40mm) and easy to use. But it is necessary to cool them properly so that the operation is good and so that the service life is long.

2.3 Waterblock

Water cooling system. Widely used in computers to cool the processor or the graphics card, it has the advantage of a better dissipation capacity than aircooling. In my case I will use one to cool the hot face of the Peltier modules and another to recover by conduction the cold generated by the other side of the Peltier modules.

2.4 Thermal pad

It is positioned between the Peltier module and the waterblock. Is the lens the same as the thermal lug: to ensure good thermal conduction. This one is better with a thermal pad than with the thermal paw. It also has the advantage of not being tacky and having a longer life.

2.5 Ventilated radiator

This is an important element, it allows the evacuation of the heat generated by the Peltier modules. Without radiator the cold generator could not work.

2.6 Circulators

As you have seen the system is composed of a cold circuit and a hot circuit to evacuate the heat. For this I use two pumps that I used before for drinks.I plan to replace them with circulators to have a higher flow and reduce noise.

2.7 12v power supply

It is essential to use a good power to operate the peltier modules correctly is able to connect enough to cool well.

For the choice of the power supply three criteria come into account:

• The price
• The need for power
• The congestion
• Reliability / security

At the moment I am using a computer power supply with an intensity of 20A for the current of 12V. But I plan to use between 3 and 4 peltier modules. For now my diet is not enough power supply. I am looking to find another food at a reasonable price.

2.8 The alcohol antifreeze

It is necessary to have an antifreeze because in case of malfunction, the ice is formed, it can break some elements such as waterblock or pipes.

To calculate the temperature of gel according to the rate of alcohol I use this web site :

http://www.spiritueuxmagazine.com/2014/07/comment-calculer-la-temperature.html

= - ((concentration of the daughter solution / 2) +3)

For the dilution I use the formula indicated on this site :

http://www.fairesagnole.eu/homedistiller_fr/dilute.htm

= Volume of stock solution X ((Concentration of stock solution / concentration of daughter solution) - 1)