Clean Room Cooling

We need to power one full disk of modules over the next year or so (2000). The power on the disk and in the hut can be predicted using the power estimate from Prague.  A disk will have upto 132 modules, each using 7 W nominal (10 W max.) including power in tapes etc.  So we need about 924 W cooling for the disk (1320 W max.)  The water cooler unit we have now is 1.7 kW maximum electrical power, this will suffice for the 1/4 disc tests. Probably not powerful enough for a full disc, but it cannot be used anyway (needs biphase cooling, not water!).

The LV power-supplies are about 50 % efficient, so in the DAQ hut they will generate a similar heating as on the disc. We also have (or will have) 2 PC's (2 x 300 W), readout VME modules (guess 200 W total for CLOAK, SLOG, Biphase encoder, MUSTARD, Rudge receiver), a NIM crate (200 W), 2 people (2 x 100 W), bias supply (100 w). This comes to about 2.2 kW. This will be removed by an overhead cooling system which re-circulates the air in the room via a cooled radiator which has NIKHEF's cooling water flowing through it. The unit claims to handle 4 kW of heat, but this must also depend on NIKHEF's cooling water temperature, so may not be fully achieved. Still, it should cope with the 2.2 kW needed.

The DAQ hut also has an air extractor to the outside world (switch and valve control in the storage hut above the DAQ room). This may be useful, but we would have to take care not to spoil the clean-air system: we must not suck in dirty air from outside, nor pump air out causing a loss of overpressure in the clean-room.

If we do need more cooling later in the DAQ hut, it looks relatively easy to copy the one already in place, doubling the cooling power. Water-cooled racks would be too tall to fit in the rack.

N. Hessey 10/12/99.