Abstract

A typical economizer in an air conditioning system is investigated in this paper. New operating strategies of the economizer are proposed. An economizer consists of three coupled dampers--an outdoor air, a recirculation, and a discharge damper--controlled so that the amount of outdoor air may be varied from a minimum to 100% of the supply air. Traditionally the three dampers are coupled. In a new strategy only the outdoor and recirculation dampers are coupled and the discharge damper is always fully open during operation. An additional strategy involves linearizing the damper area as a function of the control signal by means of a software algorithm. Fan energy requirements for the new strategies are compared to those for the traditional strategy. The amount of fresh air may be controlled by heating and cooling considerations or by indoor air quality considerations. Carbon dioxide (CO$\sb2$) concentration is an indication of indoor air quality. The objectives of the investigation were to determine the best strategy to minimize fan energy consumption, and to control ventilation by demand as indicated by room CO$\sb2$ concentration. (Abstract shortened by UMI.)