Analyzing Optimal Operating Points of Air and Water-Cooled Chillers Used in an Office Building

Abstract

AbstractWith the huge development of big cities, there was an increase in the number of large buildings used for commercial and administrative purposes and, as a result, the need to use air conditioning systems with lower energy consumption and that guarantee thermal comfort. Air-water-type air conditioning systems are commonly used. In order to operate those conditioning systems, air or water-cooled chillers are used. In this work, a mathematical effectiveness model is used to represent the thermal behavior of a forced circulation cooling tower, which was incorporated into the existing chiller’s model of the simulator of Edifício Moderno, enabling the optimization of the operation of both air and water-cooled chiller. Hence, the optimal operating points of both types of chillers are compared. Two different objective functions are used in optimization problems. Simulation results show a reduction of at least 14% in the energy consumed when the air condenser is replaced with the water condenser. Moreover, manipulated variables vary less to control the operation of water-cooled chillers. The optimization problems were easily solved and can be used not only to optimize the operation of the air conditioning system but also to understand the operation of chillers.KeywordsAir-water conditioning systemsCooling towerOptimization