·The loop is closed: the same chilled water circulates from the chillers to every CRAH coil and back. Only heat leaves the building, carried off by the air-cooled condensers.
·Chillers are air-cooled. Fans push outdoor air across the condenser coil, which rejects the loop heat to the atmosphere. There is no cooling tower, no condenser-water loop and no evaporation.
·Air-cooled rejection follows the outdoor dry-bulb temperature: hot afternoons raise condensing pressure and cut chiller capacity.
·A CRAH has no compressor. It is a filter, a cooling coil, a fan and controls: it moves heat from the air into the chilled water.
·Each CRAH branch has a water bypass. Opening it sends flow past the coil instead of through it — used for minimum loop flow, freeze protection and isolating a coil without stopping the loop.
·Supply air is ducted from overhead into the cold aisle, crosses the racks, and returns from the hot aisle to the units. There is no raised-floor plenum.
·Every kilowatt this plant uses is made on site by Bloom Energy fuel cells. There is no utility feed and no diesel generator, so losing a Bloom block is a loss of capacity — not a switch to another supplier. Cooling demand and electrical capacity are the same problem seen from two sides.