Task: In the last few summers were hot leading to higher temperatures at the ESR roof, which led to temperatures in the BLM electronic rack above 35 C. Temperatures close to 40 C may lead to electronics Failure. For instance all CAEN products are rated to operate up to 40 C .
There is a air-condition unit installed on the top of the electronics rack. The unit model number is: TEXA ~DEK15BT0B, manual C17000199 describes the thermostat. The manufacturer recommends to set it to 30 C. If the temperature goes 2 K above the set point the unit will be engaged. One user is expected to set the temperature, hysteresis and if the evaporator fan should be always on/off/auto.
In the experiments described bellow the following tasks were accomplished:
A RPi with a temperature sensor is used to monitor the temperature in the rack bellow the NIM crate positioned at the bottom. Here is the starting configuration:
The period of oscillation changes. It is most likely related to outside temperature.
I have measured the temperature above the DAQ too. Here is a photo of the second sensor read via an Arduino.
The temperature was the same for both sensors. Hence there is sufficient air mixing.
When increased the fan speed to High the temperature of the 24 ch card dropped to 27 C . Note that the temperature is available via the ssh tool too.
Moved the second sensor outside of the rack. It is now measuring the hall temperature.
The outside temperature is 23 C.
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.
Based on the estimate we need of order of 1600-1700 W cooling power. So lets use 1750 W for the search. 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.
Therefore a DEK20 is the minimum suitable choice for the rack cooling. A DEK30 is to be considered if additional BLM will be operated from the same rack.