"A risk assessment of the Piql Services" by FFI

Appendix C Storage Room Calculations

C.1 Temperature Increase in Storage Room

Calculations by Odd Busmundrud, FFI

Temperature change in a system can be calculated from the energy flow and heat capacity. dT/dt=(energy input minus energy loss)/(heat capacity), where dT/dt is temperature change per time.

In the case of the storage room, the energy input is the electrical power supplied to the room. (Supposing there is no other energy source, like external heating)

The energy loss is thermal energy transported out of the room by air flow, and by conduction through walls, ceiling and floor.

Energy input

Each robot has an average power consumption of 78 W.

The charger has a power consumption of 1840 W during charging. The charging of two 12 V 105 Ah batteries would take approximately 3 hours, supposing 50% efficiency.

The total average power consumption of one robot (including charging) can be calculated to be approximately 150 W.

In addition there are probably other energy sources like lightning and data equipment. There is not sufficient information on this. However, suppose there are ten 60W light bulbs in the room, this would add another 600 W.

Also, if there is one data server and other data equipment, an educated guess is that this could add another 500W.

The total energy input to the room, with two robots, would then be approximately 1400.

With no lightning, this would be reduced to 800 W.

With all data equipment outside the room, the power input would be further reduced to 300 W.

The total energy input could then be estimated to be between 300 and 1400 W.

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FFI-RAPPORT 16/00707