BUILDING AUTOMATION SYSTEM

Abstract

Conventional chiller control schemes are designed to maintain a constant chilled water supply temperature regardless of the cooling load and outdoor conditions. However, the work input per ton of refrigeration will be higher when compared to the evaporator supplying a higher chilled water supply temperature to meet the cooling load requirement. The higher work input is due to the low suction pressure at the corresponding temperature (refer to page 36 for further clarification). There are many ways in which one could implement energy conservation measures on a chiller during part-load situations. Raising the chilled water supply temperature while still ensuring that the comfort cooling requirements of the conditioned space are met is one possible way. The main objective of this research project is to develope and implement a chilled water reset control strategy that would to meet the thermal comfort of the conditioned space and to optimize the chiller plant's performance based on chilled water resetting using an Energy Management System (EMS). The control strategy consists of 2 chilled water reset routines; "knowledge-base" routine and "search" routine. The main feature of the control strategy is to ensure that temperature possible. The required chilled is determined in the Altogether 4 computer water shortest programs supply time were utilized in this project. Two programs were written in Turbo Basic for verification of the theoretical work. A chiller simulation program was sought from a major chiller manufacturer to confirm the potential energy savings of chilled water reset. The fourth program was for the operation of the EMS incorporating the proposed control strategy. An energy saving of 10% was realized through the implementation of the proposed chilled water reset. Other observations and findings from the results obtained were also discussed. Some recommendations for the scope of future work that could be carried out to understand chilled water reset better were also suggested.