Thermal analysis of a data centre cooling system under fault conditions

This paper describes the modelling and analysis of a 5 MW chilled water plant used for the cooling of a recently constructed data centre in the UK. The model was developed using the TRNSYS software with the aim of studying the impact of perturbations such as chiller failure on the water and air temperatures in the system. The model includes the chillers, hydraulic network (piping, valves and pumps) and individual water-to-air heat exchange units. The coupling between the data centre air temperature levels and the cooling plant has enabled a full assessment of the cooling system design in response to system perturbations to be carried out. The paper examines a number of scenarios involving the failure of the chillers and shows how the inherent thermal inertia of the system plus additional inertia achieved through buffer vessels allowed a suitable design to be achieved. The effective sizing of these vessels could not have been achieved with confidence without the use of transient analysis of the complex system dynamics.