This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision | ||
hi:cooling:cooling:blmrackcooling [2023/02/01 13:40] p.boutachkov |
hi:cooling:cooling:blmrackcooling [2023/02/01 21:10] (current) p.boutachkov |
||
---|---|---|---|
Line 21: | Line 21: | ||
{{: | {{: | ||
- | * All electronics off, AC set to 25 C. Temperature in the rack __28.3 C__. The switch and ~RPi are heating the rack. | + | * All electronics off, AC set to 25 C. Temperature in the rack __28.3 C__. The switch and RPi are heating the rack. |
* Switched on the NIM Crate. Now one can see the AC turning ON and OFF. | * Switched on the NIM Crate. Now one can see the AC turning ON and OFF. | ||
- | [img(50%+, | + | |
+ | {{: | ||
The period of oscillation changes. It is most likely related to outside temperature. | The period of oscillation changes. It is most likely related to outside temperature. | ||
- | * Switched the Tek ~MSO44 scope. The temperature in the rack is __28.3 C__ but there are no more oscillation. Seems the AC is ON all the time | + | * Switched the Tek MSO44 scope. The temperature in the rack is __28.3 C__ but there are no more oscillation. Seems the AC is ON all the time |
* Switched the CAEN HV, no HV ON. The temperature in the rack is __31 C__ | * Switched the CAEN HV, no HV ON. The temperature in the rack is __31 C__ | ||
* Switched the DAQ electronics ON. The temperature in the rack got up to __ 34.5 C __. During the night it went down to __ 33.6 C__ | * Switched the DAQ electronics ON. The temperature in the rack got up to __ 34.5 C __. During the night it went down to __ 33.6 C__ | ||
* Added a triangle shape " | * Added a triangle shape " | ||
- | [img(30%+, | + | |
+ | {{: | ||
* Removed the paper " | * Removed the paper " | ||
* Removed the HV main frame, the temperature dropped from __31 C__ to __26 C __ | * Removed the HV main frame, the temperature dropped from __31 C__ to __26 C __ | ||
- | [img(30%+, | + | |
+ | {{: | ||
* Installed the HV under the scope, above the DAQ. Turned it on. The temperature stabilized at __31.5 C __. | * Installed the HV under the scope, above the DAQ. Turned it on. The temperature stabilized at __31.5 C __. | ||
* There is a possibility to measure the HVCardsTemperature. The temperature is __ 30 C__ | * There is a possibility to measure the HVCardsTemperature. The temperature is __ 30 C__ | ||
- | [img(30%+, | + | |
+ | {{: | ||
* Installed the HV under the DAQ in place of the NIM bin. The temperature stabilized at __ 29.5 C__. The HV card temperature is __ 29 C__. | * Installed the HV under the DAQ in place of the NIM bin. The temperature stabilized at __ 29.5 C__. The HV card temperature is __ 29 C__. | ||
- | [img(30%+, | + | |
+ | {{: | ||
* Installed the NIM bin above the HV and the DAQ above the NIM bin. everything is on now. The temperature stabilized at __ 29.1 C __. | * Installed the NIM bin above the HV and the DAQ above the NIM bin. everything is on now. The temperature stabilized at __ 29.1 C __. | ||
- | [img(30%+, | + | |
+ | {{: | ||
* Open the front and back door. The temperature now is __ 24 C __. The HV card temperature is 29 C. As this does not change I am not sure if the HV card reading is reliable. | * Open the front and back door. The temperature now is __ 24 C __. The HV card temperature is 29 C. As this does not change I am not sure if the HV card reading is reliable. | ||
* Christian set the AC set point to __ 23 C__, hysteresis to __ +3 C__. The temperature is now __ 27 C __. The second sensor above the DAQ shows __ 27 C__ too. | * Christian set the AC set point to __ 23 C__, hysteresis to __ +3 C__. The temperature is now __ 27 C __. The second sensor above the DAQ shows __ 27 C__ too. | ||
* Used the CAEN Java tool. The fan speed was set to Med. The HV card temperature was __ 28 C__ for the 24 Ch card and __ 27 C __ for the 12 Ch cards. | * Used the CAEN Java tool. The fan speed was set to Med. The HV card temperature was __ 28 C__ for the 24 Ch card and __ 27 C __ for the 12 Ch cards. | ||
I have measured the temperature above the DAQ too. Here is a photo of the second sensor read via an Arduino. | I have measured the temperature above the DAQ too. Here is a photo of the second sensor read via an Arduino. | ||
- | [img(30%+, | + | |
+ | {{: | ||
The temperature was the same for both sensors. Hence there is sufficient air mixing. | The temperature was the same for both sensors. Hence there is sufficient air mixing. | ||
Line 53: | Line 65: | ||
Moved the second sensor outside of the rack. It is now measuring the hall temperature. | Moved the second sensor outside of the rack. It is now measuring the hall temperature. | ||
- | [img(30%+, | + | |
+ | {{: | ||
The outside temperature is __ 23 C__. | The outside temperature is __ 23 C__. | ||
- | * Leave the CAEN HV on, turn off the DAQ, scope and NIM crate. The temperature stabilized at __ 28 C __ | + | |
Observations: | Observations: | ||
- | * The maximum temperature in a close rack was reached with the paper roof on to of the HV: __ 35 C__. | + | |
- | * The minimum temperature in a close rack was __ 26 C__. Reached with the HV removed from the rack. Note that the AC set points is __25 C __. | + | * The minimum temperature in a close rack was __ 26 C__. Reached with the HV removed from the rack. Note that the AC set points is __25 C __. |
Therefore the AC has sufficient cooling power to take care of the system without the HV. The HV is the main heat load. | Therefore the AC has sufficient cooling power to take care of the system without the HV. The HV is the main heat load. | ||
Here is an estimate of the power generated from the electronics. | Here is an estimate of the power generated from the electronics. | ||
- | [img(30%+, | ||
- | These are the parameters of the [[DEK15|files/ | + | {{: |
- | [[DEK20|files/ | + | |
+ | These are the parameters of the {{ : | ||
+ | {{ : | ||
Based on the estimate we need of order of 1600-1700 W cooling power. So lets use 1750 W for the search. | Based on the estimate we need of order of 1600-1700 W cooling power. So lets use 1750 W for the search. | ||
- | A ~DEC20 | + | A DEK20 at __ 35 C __ ambient temperature should be able to cool down to __ 30 C __. This is a drop in replacement of a DEK15. It is 6 kg heavier than DEK15. |
+ | |||
+ | A DEK30 can cool bellow __ 20 C __ when operated at __ 35 C __ room temperature. But it requires more space and is 80 kg | ||
+ | |||
+ | As extreme case lest take __ 40 C __ hall temperature. The the DEK20 should stabilize the rack temperature just bellow __ 35 C __. A DEK30 unit will no have problems keeping the temperature bellow __ 20 C __ even at __ 40 C __ ambient temperature. | ||
- | A ~DEC30 can cool bellow __ 20 C __ when operated | + | Therefore a DEK20 is the minimum suitable choice for the rack cooling. |
+ | ====== Summary ====== | ||
+ | * The main source of heat is the CAEN HV. The heat output of the rest is much lower. | ||
+ | * Placing the HV frame under the scope has the largest effect on the cooling efficiency in the rack. | ||
+ | * The optimum configuration is with the CAEN HV at the bottom. Speculation: | ||
+ | * The cooling power needed to control the temperature in the rack is of order of 1700 W. I expect to add 4 more units, 2 LED drivers and 2 switching matrices. The will add of order of 40 W. Hence, I use 1750 W for the estimates | ||
+ | * A DEK15 unit operating in __ 35 C __ hall temperature will stabilize the rack temperature at around __ 40 C __. | ||
+ | * A DEK20 unit operating in __ 35 C __ hall temperature will stabilize the rack temperature at around __ 30 C __. (Note: this is a drop in replacement of DEK15, it adds 6 kg to the roof load) | ||
+ | * A DEK30 unit can keep the rack temperature bellow __ 20 C __ even in __ 35 C __ hall. | ||