Chilled Water With Cooling Towers

This example is of a Chilled Water system with Water Cooled Chillers and Cooling Towers. The Water Cooled Chiller rejects its heat through the Condenser circuit to a system of Cooling Towers. The diagrammatic may be used to schematically illustrate the mechanical operation of this class of data center for models 1 and 2, with the cabinets in open hot and cold aisles, for 21°C return air temperature set point.

The power topology represents a system with an MV/LV Transformer that feeds the IT LV Switchgear which in turn distributes power to the IT equipment through the UPS, PDU and cabling nodes. The mechanical plant is powered through separate LV switchboards in the LV Room and Mech Room. 

The data hall space is cooled by CRAC units fitted with fixed speed drives. Heat from the data hall is rejected into the chilled water system through the CRAC unit cooling coils, and distributed to the Chiller by virtue of the variable speed secondary pumps and constant speed primary pumps, hereafter referred to as the CHW Pumps. The water cooled Chiller is located internally within the mechanical plant room and the condenser circuit is supported by dedicated condenser water pumps, hereafter referred to as the CW Pumps. Both systems of pumps are housed within a dedicated mechanical plant room. Heat from the circuit is rejected to atmosphere through the system of Cooling towers.

In this class of facility (Tier III) the power infrastructure is designed with a minimum resilience of 2N. The UPS topology consist of dual (N+1) systems. 

A summary of the operating temperatures within the Data Center represented by this model is presented in the list below.

  • Target IT Inlet Temperature: 24oC (max)
  • Air Supply: 21oC Supply / 27oC return
  • Hot/Cold aisle configuration
  • Non airflow contained
  • 15oC CHW Supply
  • 21oC CHW return
  • Full load approach of 5oC

 

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