The Impact of Installing Variable Frequency Drives for Cooling Towers in Kuwait on Energy Consumption

Abstract

The application of Variable Frequency Drive (VFD) as a water and energy efficient control scheme for the operation of cooling towers (CTs) was experimentally verified using summer and winter season field data. A major concern during CT operation is the large flow of air required for cooler water temperatures that help in improving the performance of air-conditioning systems. However, this improved performance increases fan power and water consumption in dry and hot countries, such as Kuwait, due to the self-cooling property of air that results in additional water evaporation. The technical viability of VFDs for the CTs as a water and energy efficient device and to quantify the potential savings of water and electricity were experimentally verified using summer and winter season field data. The CT fans in the selected site, originally fitted with dual speed motor, were retrofitted with VFDs. The site was adequately instrumented to assess energy and water consumption of the cooling production system while operating the CTs' fans with constant air flow alternatively either at low or high speed through the building management system (BMS), and the VFD scheme keeping the CT leaving water temperature constant. The results were in favor of selecting CT with VFD as the best option to reduce electricity and water consumption.