Mixed air temperature reset by data-driven model for optimal economizer control

Abstract

An economizer system means that outside air is introduced to reduce energy consumption when the outdoor air is sufficient to be used for cooling, and adjusts the outdoor, ventilation, and exhaust damper to maintain the mixed air temperature set value during heating, ventilation and air conditioning control. The set values for economizer control include high and low limit that determine whether to operate economizer, and mixed air temperature. At this time, the mixed air temperature is set to a fixed value. Such a fixed set value may cause problems such as energy waste because it does not consider changes in indoor and outdoor environments. Therefore, in this study, an optimal economizer control was developed that produces the maximum economizer effect by resetting the mixed air temperature set value considering the indoor and outdoor conditions. For this, a data-driven prediction model was developed, and based on the prediction model, an optimal economizer control was developed that resetting the mixed air temperature set value. And the developed control was evaluated by TRNSYS-Matlab co-simulator, and as a result, the mixed air temperature set value was changed in real time, and energy consumption was reduced by about 20% compared to the dry-bulb temperature control.