This paper presents the results of an experimentally validated Computational Fluid Dynamics (CFD) model for a data center with fully implemented fan curves on both the servers and the Computer Room Air Conditioner (CRAC). Open and contained cold aisle systems are considered experimentally and numerically. This work is divided into open (uncontained) cold aisle system calibration and validation, and fully contained cold aisle system calibration and leakage characterization. In the open system, the CRAC unit is calibrated using the manufacturer fan curve. Tiles flow measurements are used to calibrate the floor leakage. The fan curves of the load banks are generated experimentally. A full physics based model of the system is validated with two different CRAC fan speeds. The results showed a very good agreement with the tile flow measurements, with an approximate average error of 5%, indicating that the average model prediction of the tile flow is five percent lower that the measured values. In the fully contained cold aisle system, a detailed containment CFD model based on experimental measurements is developed. The model is validated by comparing the flow rate through the perforated floor tiles with the experimental measurements. The CFD results are in a good agreement with the experimental data. The average error is about 6.7%. Temperature measurements are used to calibrate other sources of containment and racks leaks including mounting rails and clearance between racks. The temperature measurements and the CFD results agree well with average error less than 2%. Detailed and equivalent modeling methods for the floor and containment system are investigated. It is found that the simple equivalent models are able to predict the flow rates however they did not succeed in providing detailed fluid flow information. While the detailed models succeeded in explaining the physical phenomena and predicting the flow rates with noticeable tradeoffs regarding the computational time. Important conclusions can be drawn from this study. In order to accurately model the containment system, both the CRAC and the load banks fan curves should be simulated in the numerical model. Unavoidable racks and containment leaks could cause inlet temperature increase even if the cold aisle is overprovisioned with cold air. It is also noted that heat conduction through the floor tiles causes a slight increase the inlet temperature of the cold aisles. Finally, it is noteworthy that using detailed modeling is necessary to understand the details of the thermal systems, however simpler and faster to compute equivalent models can be used in extended optimization studies that show relative rankings of different designs.

The use of air containment systems has been a growing trend in the data center industry and is an important energy saving strategy for data center optimization. Cold Aisle Containment (CAC) is one of the most effective passive cooling solutions for high density heat load applications. Cold Aisle Containment provides a physical separation between the cold air and the hot exhaust air by enclosing the cold aisle, preventing hot air recirculation and cold air bypass. This separation provides uniform inlet air temperatures to the servers, which can further contribute to overall data center efficiency. This paper includes the thermal test data for a data center lab with and without a CAC set up. The paper quantifies the thermal impact of implementing a CAC system over an open Hot Aisle/Cold Aisle (HA/CA) arrangement for three different cabinet heat load conditions at two different CRAC (Computer Room Air Conditioner) return air set point conditions. It studies the advantages of CAC over standard HA/CA arrangement. A case study has been presented showing a cooling energy savings of 22% with the use of a CAC system over a standard HA/CA arrangement.

Access networks provide the last mile of connectivity to telecommunications customers throughout the world. Voice, data, and video services through fiber, copper, and wireless media are all delivered to the end user by the access portion of the network. In an access network, thermal management of active electronics and optical devices is critical to network reliability and performance. In these networks, outside plant telecom enclosures provide environmental protection for both active electronics and optical devices. These enclosures must incorporate cooling systems that support thermal requirements of the electronic and optical components. And, with ever-increasing sensitivity to environmental impacts, the enclosures and cooling systems must have minimal aesthetic and acoustic impact to their surroundings. Additionally, the enclosures must be developed with high sensitivity to cost as they are typically deployed in large number throughout a telecom service area. A number of thermal technologies are employed for thermal control of these enclosures. These includes air conditioning, heat exchangers, thermoelectric coolers, direct air filtering, and double-walled construction. In this paper, the double-walled construction technique and its impact on thermal performance will be discussed in detail.

Telecommunication shelters form an important component at different levels of the wireless access network. They are commonly used as transmission hubs and base transceiver stations. The telecom shelter protects wireless transmitters and receiver electronics in the wireless network. They are stand-alone, modular structures that are supported with their own electrical and HVAC systems. Based on their locations they are designed to work over a wide range of environmental conditions with temperatures ranging from −40°C to 55°C and may be exposed to high humidity, and saline and corrosive environments. Cooling/heating systems typically consume 30% of the energy required to operate a wireless cell site. There is, therefore, an impetus to embark on initiatives to reduce this percentage as part of an effort to both save money, and to reduce the carbon footprint. In this paper various thermal design options to cut down on cooling/heating energy loads for these shelters are discussed. The effect of substituting active cooling/heating equipments used in shelter with a hybrid one. The hybrid cooling system consists of both the air conditioner and a blower. CFD analysis is performed to compare these designs and come up with a robust design solution. The best cooling methodology showed an energy saving of 40% with minimal impact on design temperature.

Access networks provide the last mile of connectivity to telecommunication customers throughout the world. Voice, data, and video services through fiber, copper and wireless media are all delivered to the end user by the access portion of the network. In an access network, thermal management of active electronics and optical devices are critical to network reliability and performance. The outside plant telecom enclosures provide environmental protection for both active electronics and optical devices. These enclosures must incorporate cooling systems that support thermal requirements of the electronic and optical components. In addition to the heat load from the electronics there is also solar loading on the cabinet, which needs to be taken into account when designing a cooling system.In order to reduce the solar loading, a double walled cabinet was shown to be an effective method. In this method, air is forced between the telecommunication cabinet and the outside wall. Although the air gap is effective in reducing the solar load, its thickness was found to be insignificant [1]. Thus to reduce the cabinet dimensions, double walled cabinets with smaller air gap are recommended. However, this may impact the energy consumption of the fan and may pose acoustic problems. Hence, a study was carried out for different fan configurations and the effect it had on cabinet temperature and energy consumed by the fans were studied. From the study it was found out that there was significant change in energy consumed by fans when their location is changed.