Fault Detection and Diagnostics for Rooftop Air Conditioners

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2 DATA SOURCES USED FOR EVALUATION AND DEMONSTRATION
2.1 Overview
There is a lot of test data available from earlier research projects performed at
Herrick laboratories for the purpose of validating FDD techniques and models for
packaged air conditioning equipment. Data taken by Breuker (1997b), Chen (2000), and
Harms (2002) were used to validate the FDD techniques presented in this report.
The earlier laboratory data sets do not include some factors that would be
experienced in the field. Examples include ambient weather conditions that appear in the
field but are typically not measured and were not considered during laboratory testing,
such as solar radiation, rain, and wind. These factors can influence the performance of the
unit through an impact on the condenser heat transfer characteristics. Also the damper
position changes the air flow rate, while the laboratory experimental data was collected
with a constant air flow rate. Since the mixing chamber is small, outdoor air and return
air are not mixed well and different damper positions also have some impact on mixing.
If not properly considered, changes in damper position could lead to classification errors.
The impacts of these factors are unknown and deserve further research in a field situation.
2.2 Previous Data Sources
2.2.1 Mark Breuker’s Data
Two types of laboratory data were collected by Breuker (1997b) under controlled
conditions for a 3-ton Carrier rooftop air conditioner with a short-tube as the expansion
device. One is normal operation data, which were used to build a normal operation model,
and the other is faulty operation data, which were collected under various simulated faults
and used to evaluate FDD performance.