Fault Detection and Diagnostics for Rooftop Air Conditioners

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interactions among multiple factors. From the perspective of mathematics,
transformation could result in decoupling.
3. The underlying physics for HVAC&R equipment were utilized wherever possible.
By analyzing the different faults deeply, the commonness and characteristics of
faults and decoupling features could be found. Deep understanding of the physics
of the system also contributed to development of models (virtual sensors) that can
be used to estimate some measurements that would require expensive
measurements.
4. Manufacturers’ rating data such as compressor maps, TXV maps and system
capacity rating data were used extensively, because they are not only readily
available at no cost, but also are generic and reasonably accurate.
5. The focus was on development of generic FDD methods for packaged air
conditioners. Unlike a critical FDD system which is engineered for a specific large
system, FDD for packaged equipment needs to be adaptive and generic (systemindependent)
for the same type of system, or at least for similar models from the
same product family. The application of generic FDD methods would reduce the
per-unit costs.
Both laboratory and field data were used to validate the proposed techniques as
follows:
1. Field setups were used to investigate the impact of practical factors on FDD
application.
2. Laboratory setups will be used to test overall performance of FDD methods in a
controlled environment with individual and multiple-simultaneous faults artificially
imposed at known levels.
Field data were also used to evaluate the impact of faults on system performance
and to perform initial economic assessments for FDD.