Demand Controlled Economizer Cycles: A Direct Digital Control Scheme for Heating, Ventilating, and Air Conditioning Systems

摘要

An improved economizer control was developed which based the control decision on the measured demand for hot and cold air. The control system was activated in January of 1984 and was operated through February, March, and April. Data taken during these months showed the experimental control system reduced the coil operating costs by over 20% during February and March, and reduced costs by over 30% during April. A computer simulation of this system predicted an annual savings of 22%, or approximately $2200 for the HVAC system being studied. The payback period for the demand controlled economizer ranged from 6 months (if added to an existing DDC system) to 2 years (if installed as a stand-alone system). In addition to studying the performance of the experimental control system, the instrumentation installed as part of this experiment allowed the entire HVAC system to be studied. Temperature sensors, coil stratification, and perimeter heating systems are among the topics discussed in this thesis.