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This paper looks at hydraulic modeling as a tool to optimize energy savings from part-load pumping strategies, taking advantage of the fact that redundant pumps and other equipment are typically installed in data centers. The commercially available hydraulic analysis package used for analysis is capable of solving for balanced flows and pressures throughout the system, and includes detailed models of all pumps, heat exchangers, valves, pipes and fittings. It allows individual pipelines to be easily shut off, simulating failure modes, and also allows pump speeds to be reduced, allowing for simulation of VFD operation. The procedures and results are demonstrated for a theoretical data center with a 5.5 MWIT Load and 12°F (6.6°C) water-side delta t. Pumping energy savings of over 30% were obtained by making optimal use of redundant equipment. On the other hand, pumping penalties of up to 20% were also noted through careless selection and use of redundant pumps. [ABSTRACT FROM AUTHOR]

This paper looks at hydraulic modeling as a tool to examine failure modes of a central plant chilled-water system. The program is capable of solving for balanced flows and pressures throughout the system and includes detailed models of all pumps, heat exchangers, valves, pipes, and fittings. It allows individual pipelines to be easily shut off, simulating failure modes, and also allows redundant pumps and chillers to be turned on in response to failures. The procedures and results are demonstrated for a theoretical data center with a 5 MW IT load and 12°F (6.6°C) water-side delta t. The results are visualized by creating 2-D plots of the control valve pressure drops in the distribution grid. [ABSTRACT FROM AUTHOR]

The decision to activate an air-side economizer is typically based on a comparison of the outdoor and return air enthalpy of the two airstreams; the stream utilized is the one with the lowest enthalpy. For data centers that comply with the high supply air conditions recommended in ASHRAE's Thermal Guidelines for Data Processing Environments (ASHRAE 2004a); however, conditioning the return air typically only requires sensible cooling. If the outdoor air with low enthalpy but high dew point is utilized, a dehumidification process is needed in addition to a sensible cooling process. This dehumidification process (desiccant or otherwise) will have a COP different from sensible cooling, which will affect the range of psychrometric conditions suitable for economizer use. The purpose of this paper is to look at the efficiency of the dehumidification process (mechanical refrigeration vs. desiccant) needed to utilize this high dew point outdoor air to allow for air-side economizer operation. [ABSTRACT FROM AUTHOR]