Model-Based Diagnostics for Air Handling Units

Introduction In most large air-conditioned buildings, air-handling units account for a significant portion of total building energy consumption and have a major impact on comfort conditions and maintenance costs. The devices within an air-handling unit either use energy directly in the case of fans, or indirectly, in the case of heat exchangers, which impose loads on the chiller and boiler plant. Air-handling units can comprise a myriad of subsystems (fans, heat exchangers, humidifiers, mixing dampers, heat recovery units, filters, control valves, actuators, sensors, etc.) all of which are prone to developing faults. Sensor information from the various air-handling unit subsystems is typically available on a single network through an energy management and control system (EMCS). In practice, little analysis of the information on the EMCS network is carried out and the full potential of the hardware is therefore not realized. Significant potential exists for making better use of this information for data analysis and fault diagnosis in order to improve operations, save energy, and assure comfort conditions.

[1]  J.J. Gertler,et al.  Survey of model-based failure detection and isolation in complex plants , 1988, IEEE Control Systems Magazine.

[2]  R. Isermann,et al.  Model base fault detection and diagnosis methods , 1995, Proceedings of 1995 American Control Conference - ACC'95.

[3]  T. I. Salsbury.  A Temperature Controller for VAV Air-Handling Units Based on Simplified Physical Models , 1998 .

[4]  David Clark,et al.  HVACSIM+ building systems and equip-ment simulation program reference manual , 1985 .

[5]  Paul M. Frank,et al.  Fault diagnosis in dynamic systems: theory and application , 1989 .

[6]  David E. Claridge,et al.  Improving building energy system performance by continuous commissioning , 1997, IECEC-97 Proceedings of the Thirty-Second Intersociety Energy Conversion Engineering Conference (Cat. No.97CH6203).

[7]  Philip Haves,et al.  Condition monitoring in HVAC subsystems using first principles models , 1996 .

[8]  A. S. Glass,et al.  Preliminary evaluation of a qualitative model-based fault detector for a central air-handling unit , 1994, 1994 Proceedings of IEEE International Conference on Control and Applications.