Automated Fault Detection and Diagnostics for Vapor Compression Cooling Equipment

Automated fault detection and diagnostic (FDD) systems have the potential to reduce equipment downtime, service costs, and utility costs. However, very few commercial products exist and the ones that do exist are very specialized. This may be surprising to some, considering that FDD is very well developed for other applications such as for nuclear power plants, aircraft, chemical process plants, and to a lesser extent automobiles. However, the benefits of FDD for HVAC&R systems are lower than for critical applications such as nuclear power plants or aircraft or for production facilities such as chemical process plants. For any application, the benefits of FDD can be divided into two general categories: improved safety and reduced cost to operate. For the nuclear power or aircraft industries, safety is an overriding consideration and expensive sensors and electronics can be used within FDD systems to achieve this goal. In a chemical process plant, the output of the plant is a product and equipment failures and inefficiencies can have a significant impact on the product costs. In this case, automated FDD systems can go along way towards reducing downtime and improving production efficiencies. FDD systems are generally not necessary to ensure safety in HVAC&R applications. Therefore, the benefits must be derived from reduced operating costs. FDD applied to an HVAC system that serves a commercial building could reduce operating costs by lowering service and utility costs, and improving business productivity through reduced equipment downtime and better overall comfort. One of the primary obstacles to the development of FDD systems for HVAC&R systems has been the lack of data to quantify these potential cost savings benefits. However, in comparison to chemical process plants, the cost savings are undoubtedly a smaller portion of the costs of operating the businesses that they serve. This means that FDD systems for non-critical HVAC&R applications must have lower installed costs to achieve the same cost-to-benefit ratio. Clearly, achieving low installed costs is a critical factor in enabling the deployment of FDD systems in HVAC&R applications. Interest in FDD has grown as the costs of sensors and control hardware have gone down. In addition, there has been an emergence in the use of information technology within the HVAC&R industry for scheduling, parts tracking, billing, personnel management, etc. This has provided an infrastructure and higher expectation for the use of quantifiable information for better decision making. Finally, the structure of the industry that …