noisette123
28-02-2013, 06:17 PM
Hello All,
I have a question regarding the possible modification of a new chest freezer in order to bring the operating temperature down from -20 to -40C. Is this possible with minimal hardware changes? Here is an answer that i received from Michael St-Pierre from mytekcontrols.com.
Hello Jean-Francois,
If your electronic device that needs to be tested is relatively small, as in low heat producing, it probably would be possible to use a standard refrigerator/freezer with a modified charge. A small dedicated chest freezer would be the best candidate, but it must be fairly new, having POE or PVE type oil in the compressor.
Changing to something like R507 for the refrigerant, and bypassing the original thermostat for lower temperature operation should get you where you want to be. Some other tricks like being sure to wrap or solder bond the cap tube to the returning suction line will insure that the R507 gets fully condensed before being expanded in the freezer's evaporator.
If you start off with the dedicated chest freezer as your basis, the cap tube will likely be close to what is needed. However I can not guarantee that this is true. Many of the guys on the Xtreme Systems forum create systems like this all the time for this temperature range. You might want to join the forum, and then post your proposed project in the phase change cooling section in order to get some good feedback and help with things such as cap tube sizing.
Good luck
Is this project feasible? And if so, what problems should i expect ?
Cheers for your technical insights,
Jean-Francois
I have a question regarding the possible modification of a new chest freezer in order to bring the operating temperature down from -20 to -40C. Is this possible with minimal hardware changes? Here is an answer that i received from Michael St-Pierre from mytekcontrols.com.
Hello Jean-Francois,
If your electronic device that needs to be tested is relatively small, as in low heat producing, it probably would be possible to use a standard refrigerator/freezer with a modified charge. A small dedicated chest freezer would be the best candidate, but it must be fairly new, having POE or PVE type oil in the compressor.
Changing to something like R507 for the refrigerant, and bypassing the original thermostat for lower temperature operation should get you where you want to be. Some other tricks like being sure to wrap or solder bond the cap tube to the returning suction line will insure that the R507 gets fully condensed before being expanded in the freezer's evaporator.
If you start off with the dedicated chest freezer as your basis, the cap tube will likely be close to what is needed. However I can not guarantee that this is true. Many of the guys on the Xtreme Systems forum create systems like this all the time for this temperature range. You might want to join the forum, and then post your proposed project in the phase change cooling section in order to get some good feedback and help with things such as cap tube sizing.
Good luck
Is this project feasible? And if so, what problems should i expect ?
Cheers for your technical insights,
Jean-Francois