134 • 48. INTERNATIONAL HVAC&R CONGRESS AND EXHIBITION U ovoj studiji je razvijen numerički višezonalni model primenom TRNSYS za simulaciju termičkog ponašanja objekta. Program TRNFLOW se koristi za predstavljanje vazdušne struje unutar vertikalnih zidova i kroz ormane. Eksperimentalna merenja dobijena za različite parametre (rasipanje snage, brzina vadzušne struje) upoređena su sa numeričkim rezultatima kako bi se ispitao (validirao) ovaj model. Ključne reči: slobodno hlađenje, grejanje,

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... a, simulacija A data center is an installation that contains telecommunication equipment like servers and computers. This equipment operates with a high power density and requires important energy supplying. Most of this energy is converted into heat and dissipated in the interior volume. Therefore, the use of a cooling system becomes very essential in this case. The air conditioning system is generally used in restricted ranges of temperatures and humidity leading to very high energy consumption. The reduction of this energy consumption constitutes a challenge which should be raised. The experimental study is carried out on a small building with 42 m 3 of internal volume. Four telecom racks are installed inside the building. Racks are equipped with heating elements in order to simulate real telecom equipment. This allows controlling the power dissipation very precisely. The cooling system adopted in the building is represented by a double air circulation (counter flow) within three of the four vertical walls. The two air flows are separated by a metallic folded sheet to increase heat exchange. Fresh air coming from outside constitutes the external airflow. The internal airflow, in closed loop, allows evacuating the power dissipated by the racks. The front side of the racks faces the cold air supply, and the back side faces the exhaust hot air. Therefore, the hot/cold aisle configuration is adopted inside the building. This concept of air conditioning is an indirect free-cooling system. The equipment is cooled by using external air climatic conditions. In order to evaluate the efficiency of the installation, 50 thermocouples are set up to measure temperatures in different positions. Climatic conditions, internal heat dissipation and airflow are also measured. In the present study, a numerical multi-zone model is developed using TRNSYS to simulate the thermal behavior of a building. The TRNFLOW program is used to represent the airflow within the vertical walls and through the racks. The experimental measurements obtained for different parameters (power dissipation, airflow rates) are compared to numerical results in order to validate the model.