Co2 cartridge questions When co2 is released from the cartridges. Is the gas get cold too or just the cartridge itself only ? And will be releasing it slowly will effect the temper drop ? Thanks you
 A: It is an imprecise question.  But then, once we know exactly what question to ask, we almost always have the answer already.  So, let me try.
First of all, the $CO_2$ inside a cartridge is compressed to the point where it is a liquid at around room temperature.  When gas is released, some of the liquid boils off.
It takes energy to convert from the liquid to the gaseous phase (heat of evaporation, or heat of vaporization).  This is by the far the biggest effect.  But watch out.  The boiling off gas is created at the temperature of the liquid.  However, boiling off the gas requires energy, which comes from the heat stored in the liquid - and the liquid will cool down.
As long as there is liquid $CO_2$ inside the cartridge the boiling off gas is created at the vapor pressure determined by the temperature of the liquid.  As the gas expands adiabatically from around 70atm (near room temperature) to 1atm, it cools due to the Joule Thomson effect.  However, this is a small effect.  While it is being used in liquefying air (Linde method) it is not great for cooling a massive tank filled with a liquid, say water.
To answer the other question: The $CO_2$ liquid inside the cartridge is in close thermal contact with the cartridge wall and hence at the same temperature.  If you drop the cartridge into the tank, the liquid $CO_2$ will equal the tank temperature after some time.
From here on we enter the realm of a poorly defined engineering problem.  For instance, if the liquid in your tank is too hot, the cartridge may not be able to contain the $CO_2$ vapor pressure and start discharging uncontrollably.
If you put the cartridge into an ice bath outside your tank, you would start with $CO_2$ gas near 0°C, and you could send that through copper tubing through your tank.
Sources: $CO_2$ thermodynamic data, 
Joule Thomson Phyics Lab, Hampson-Linde cycle
