Cooling performance of a hybrid refrigeration system designed for telecommunication equipment rooms

During the last several years, the power density and thermal density of telecommunication equipments have been increased. The optimum control of the PCB surface temperature is very important for obtaining high performance and operation reliability of telecommunication equipments. In this study, the cooling characteristics of telecommunication equipments were measured and analyzed as a function of the equipments' heat density. In addition, the performance, of a novel hybrid refrigeration system for telecommunication equipment rooms was measured at various operating conditions. The PCB surface temperature ranged from 35 to 60 degrees C, which was relatively higher than the air temperature due to heat trapping and improper air distribution. The hybrid refrigeration system operated in the vapor compression cooling mode at high outdoor temperatures, but in the secondary fluid cooling mode at low outdoor temperatures. The outdoor temperature for the mode switch was approximately 8.3 degrees C. The COP of the hybrid refrigeration system was significantly enhanced at low outdoor temperatures as compared with the conventional vapor compression system due to no operation of the compressor. (C) 2006 Elsevier Ltd. All rights reserved.