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Heat transfer study in M0’using the thermistors on the APD’s and on the boards

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Starting the electronic.Calibration of the APD’s

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Elec. offElect. on

Power cooling waterThe flow is 0.14 liter/s.

The cooling power for 0.42 (out-in) is 2.5W/channel.

inout

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in

out 0.013

Elec. off Elec. on

Regulating cooling waterThe flow is 0.22 liter/s.

The cooling power for 0.013 (out-in) is 0.12W/channel

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Power coolingFailure on the main cooling circuit

on 23/9/02Effects on the temperature

of the electronic and the APD’s

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out

in

1.29

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Boards

Apd’s0.03

1

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in

out

Regulating waterTemperature increase 0.005

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Conclusions:•Temperature of APD (Thermistor) is 0.1 above cooling waterwhen the electronic is on.•When the water of the power circuit has its temperature increase by 1.34: -Temperature of APD (Thermistor) is 0.1 above cooling water -The outgoing regulating water increases its temperature by 37% and the APD’s by 30%. -The connector of the APD (on the board ) has its temperature increased by 1.34 at maximum. (it cannot be higher than the increase of the power cooling ).

All the heat going to the regulating circuit and to the APD’s goes through that connector.

Then we deduce that the connector has a temperature less than 1.34/0.3=4.4

(above the regulating water.)

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Effects on the APD’s of power variations

in the electronic.It is due to a low voltage variation

correlated to temperature variations in the control rackin the barrack.

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board

APD thermistors

0.012

0.12

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Conclusion:

The rise of the board temperature is clearly correlatedto a rise of the low voltage power supply and of its current. The rise is 4% in temperature of the board to which corresponds 12% rise on the APD thermistors.

There is more power consumption and heat release at the bottom of the board (FPPA?)