COMPARISON BETWEEN CONVENTIONAL AND LOCAL COMPUTER ROOM AIR-CONDITIONING SYSTEMS IN DATA CENTER BY CFD

摘要

The reduction of energy consumption in data centers is crucial because, recently, the energy consumption ofrnheating, ventilating, and air-conditioning (HVAC) systems has increased owing to huge amounts of datarnbeing processed by high-density information technology (IT) equipment. In general, the amount of heatrngenerated by servers and cooling capacity of computer room air conditioning (CRAC) is equal. Meanwhile,rnthe air flow rate of server is higher than that of CRAC. Under these conditions, the high-temperature air,rnsuch as the outlet air from the servers may be recirculated to the inlet of the server without being fullyrncaptured by the inlet of CRAC. Thus, the energy consumption of CRAC would become high. The advent ofrncloud service and virtualization technology has changed the operating conditions of IT equipment rapidly.rnTherefore, it is important to precisely control CRAC systems and servers based on factors such as air flowrnrate of CRAC, processing location, and server conditions.rnIn this study, the capture efficiency of CRAC (η -index) is defined as the ratio of air volume of server to thatrnof CRAC. Models for estimating indoor air flow were developed based on the thermal equilibrium in datarncenter. Two types of CRAC were assumed, namely, conventional CRAC and local CRAC. Case studies onrnseveral heat load and air flow rate of server were examined using CFD to estimate the optimal air flow raternof CRAC based on the η -index of CRAC and allowable temperature of server. Furthermore, the h value ofrnCRAC was investigated based on several processing locations and server conditions.