Energy Saving of Evaporative Coolers using Permanent Magnet Brushless Motor Drive Technology

Abstract

Evaporative coolers due to their low cost are used in most of the hot and dry regions of Iran and other countries, and are considered as one of the major consumers of electrical power. Conventional evaporative coolers use single-phase induction motors (SPIMs) connected directly to the power grid. But the benefits of these motors are very low, and their replacement with high efficient electrical motors is considered by various governing organization. In this paper, the details of using the brushless motor in the application of evaporative cooler are presented and the requirements and standards for designing the brushless motor-drive are stated. A 1/2 hp brushless motor-drive are designed and built and it is tested by a dynamometer equipment. Moreover, a 5000 m3/h evaporative cooler equipped with this brushless motor-drive is tested under the airflow rate experiment. The results obtained in both tests are compared with the test results of a typical SPIM. The results verify an increase of at least 60% for energy efficiency compared to evaporative coolers based on SPIM. Also, the economic considerations of brushless motors and other technical considerations are discussed.