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Research into the development of fault detection and diagnosis (FDD) methods as applied to heating, ventilating, air-conditioning, and refrigerating equipment has been ongoing for over a decade, and several papers have been published. However, studies specifically related to large chillers have been few despite the importance of such equipment. The objective of this paper is to propose and illustrate a simple model-based FDD method for medium to large chillers that uses sensors available in most cooling plants, allows tuning of specific thresholds so as to attain the desired compromise between robustness and sensitivity, and has the potential to be automated and implemented online. Lacking actual field data of chillers operated under fault-free and faulty operation, the performance of the proposed FDD method is demonstrated with data generated from tests on a laboratory chiller in the framework of an earlier research study. This proposed FDD scheme is based on five important characteristic features (that have been identified from 15 variables evaluated) that allow six process faults to be identified (although two cannot be done uniquely). Since large chillers are not prepackaged as is unitary equipment, their design and assembly allow selecting different subsystems for a stipulated maximum cooling capacity. In such a case, selection of specific variables needed for FDD will be impacted by different faults, depending on several aspects unique to the chiller installation: the type of chiller load control (thermostatic expansion valve or inlet guide vane), specific choice of the relative heat exchanger size, and the load fraction at which the chiller is usually operated. Hence, it is likely that some customization would be needed to adapt the FDD thresholds and association rules for each chiller installation. Different options and challenges relevant to practical implementation of the proposed FDD method are discussed. [ABSTRACT FROM AUTHOR]

Sustainable on-site cooling-heating-power (CHP) systems for large multibuilding projects require a simplified design and implementation approach from conventionally designed mini-utility-type CHP systems employing large volume/footprint, costly, high thermal mass heat-recovery- steam-generators, and 24/7 stationary engineers. This paper demonstrates the use of prefabricated, skid-mounted hybrid steam generators with internal headers, fully integrated with low pressure drop heat extraction coils located in the gas turbine exhaust and employing environmentally benign heat transfer fluids. The proposed thermal tracking integrated CHP gas cooling system includes close-coupled plate-and-frame heat exchangers, pumps, and self-regulating controls, interconnected via a closed, low-pressure, nonvolatile recirculation loop capable of efficient year-round heat transfer to on-demand HVAC&R building heat sinks, including absorption chillers. Available waste heat is transferred directly to a gas turbine exhaust, extraction heat exchanger, interconnected to a recirculating, closed-circuit, nonvolatile, low-pressure heat transfer fluid loop. Available waste heat is cascaded to serve multi-building space cooling, heating, and domestic hot water loads, which permits maintaining high log-mean-temperature-differentials at the subject extraction coil, significantly lowering gas turbine back-pressure, and permitting significant life-cycle cost savings. These benefits were demonstrated during a recent, comparative CHP study ofa 3.5 MW gas turbine installation at a central California university campus. [ABSTRACT FROM AUTHOR]