Modeling and Adaptive Control of Low Capacity Chillers for HVAC Applications

An adaptive controller for single and uneven tandem scroll compressor, packaged air-cooled water chillers is described. The designed controller allows to substantially increase the energy performance of the system, as well as to achieve excellent regulation performances in process applications. The controller parameters are adapted on the basis of estimates of the plant thermal load, that are computed by using a Kalman filter. An ad hoc approach is used to define a relay control logic, which is based on a numerical optimization procedure. To support controller design, a detailed simulation environment is developed and validated on an experimental facility. Performance of the algorithm is described with both simulation and experimental data. At low part load ratio values the proposed algorithm grants a 0.6e0.7 K improvement in the regulation performance in terms of supply water temperature standard deviation and mean supply water temperature deviation. The unit energy efficiency improvement with respect to supply water temperature control varies from 7.3% to 3.0% while the experimental seasonal energy efficiency rating improvement is 9.1%.