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Based on the features of large heating power per unit volume and small cooling surface area, the thermal management is one of the key technologies and plays a significant role for the pulsed inductor. A mathematical model that describes the heat transfer and thermal accumulation processes with the operating condition of periodic pulse loading for the pulsed inductor has been developed and validated in this paper, and the model results show a fine accuracy as compared with the test data. In addition, a computer code has been implemented to simulate the thermal accumulation and performance of natural cooling with different operating conditions (as the various of pulse voltage, pulse spacing, and pulse duration). The results show that the pulse voltage, pulse spacing, and pulse duration are the focus factors to the thermal accumulation for the pulsed inductor, and the effect of the natural cooling by surface area of the inductor is poor under the periodic pulse loading. [ABSTRACT FROM PUBLISHER]

This paper proposes a conceptual design strategy for an optimal cooling system, typically used in several microelectronic devices. The methodology was implemented using the entropy generation minimization (EGM) criterion, powered by the cuckoo search (CS) algorithm. EGM-CS methodology was addressed to design rectangular microchannel heat sinks, utilizing high thermal conductive graphite as build material and a water-based colloid as coolant. This strategy was implemented under different hydrodynamic conditions, where it showed strong capability to achieve optimal designs with flowing nanofluids in either laminar or turbulent regimes. In addition, two types of nanoparticles were considered, i.e., Al and TiO2, with several values of volume fraction, as a passive mechanism for enhancing overall system performance. It was corroborated that all considered flowing colloids in laminar regime improve the thermal efficiency of the system. Moreover, an additional enhancement of this performance was observed with smaller nanoparticle concentrations (e.g., 0.01 wt/wt%), which also reduces the side effects due to nanoclustering. Furthermore, fluids with titanium dioxide nanoparticles showed slightly better thermal performance enhancement compared to aluminum particles. [ABSTRACT FROM AUTHOR]

Optimal scheduling and robust sequence control of a central chiller system with thermal energy storage may not be a straightforward solution to reduce building cooling load demand (CLD) due to unpredictable thermal comfort requirements and the stochastic nature of occupancy-dependent CLD. One potential way to address this challenge is to design and develop an energy management strategy (EMS) for a zone-variable air volume unit. This paper proposes an EMS to reduce CLD by deciding the zone reference setpoint temperature based on fuzzy logic strategy (FLS) and zone thermal models. The objective is to reduce zone CLD while maintaining zone temperature and zone thermal comfort margin within the threshold limits. In this context, first, we modeled the zone thermal behavior using an artificial neural network (ANN) approach to predict zone temperature for next time slot, modeled the zone cooling energy behavior using a regression approach to predict zone CLD for the next time slot, and estimated the zone occupancy status using noise data. Second, we implemented zone thermal feedback model and comfort margin based on zone thermal conditions and predicted mean vote index, respectively. Finally, we implemented an EMS that includes both demand supply strategy and cooling load demand reduction strategy based on one time-slot ahead prediction. The novelty of the proposed EMS lies within the zone CLD reduction using FLS, predicting zone thermal behaviors using an ANN and a regression approach, estimating zone occupancy using noise data, and maintaining zone thermal comfort margin within the threshold limits. Historical data from a commercial building in Singapore are used to demonstrate the effectiveness of the proposed EMS. [ABSTRACT FROM AUTHOR]

Aisle containment separates hot and cold aisles in air-cooled data centers to prevent hot air recirculation into cold aisle and decrease temperature nonuniformity among the servers. Uniform server inlet temperatures allow the cooling system to operate more efficiently at a higher evaporator temperature. Lower cooling power consumption can be achieved by optimizing the combined power consumption of the chillers and the computer room air handlers (CRAHs) fans. CRAH bypass (BP) is proposed, in which additional fans at the tiles induce a fraction of tile flow from the room into the plenum through low-resistance ports or leakage paths, thus decreasing the airflow passing through the high pressure resistance of the CRAH heat exchangers and filters and associated fan power usage. A further advantage of the proposed induced CRAH BP is the elimination of leakage as a result of reversing the room-plenum pressure difference. However, in order to keep the enclosed-aisle temperature below acceptable limits (typically ≤27 °C), the chiller needs to operate at a lower, less efficient temperature. This paper presents the experimental verification of a flow network model (FNM) in a data center test cell demonstrating the proposed induced CRAH BP concept. Exercise of the verified FNM in conjunction with a thermodynamic model of the cooling infrastructure (TDM) confirms that there is an optimum BP fraction that minimizes the combined chiller and CRAH fan power consumption. [ABSTRACT FROM AUTHOR]

This article proposes a novel optimal sizing method for the energy station in the multienergy system (MES) integrated with data center. First, an overall framework of the energy station, data center, and multienergy loads is constructed to describe the interconnection of energy system and information system. Then, the dynamic voltage frequency scaling (DVFS) technique, the thermal inertia, and the deep coupling relationships of the electricity load, waste heat, cooling load, and workload in the data center are respectively modeled. On this basis, the optimal sizing model of the energy station is established, in which the data center can participate in the integrated demand response by the DVFS technique and thermal inertia. The capacity of energy station and the scheduling schemes of energy devices and servers are optimized simultaneously to coordinate the energy flow and information flow. Based on the quasi-steady-state assumption of thermal balance, the model is simplified to a mixed-integer quadratic program problem, and it is solved by Gurobi. Case studies based on a real-world test system in China illustrate that the integration of data center can be utilized to reduce the total cost of energy station planning in MES. [ABSTRACT FROM AUTHOR]

Magnetic-thermal-fluidic analyses were conducted to assess the cooling performance of magnetic nanofluids by comparing the performance with that of transformer oil and air using the fully coupled finite element method (FEM) considering the magnetoconvection phenomena. Magnetic nanofluids (MNFs) have been studied extensively for bio- and nanotechnology applications. In particular, some studies reported that the MNF has good characteristics for thermal management and electric insulation in experiments. With this motivation, this study focused on the cooling performance of MNFs including the experimental and numerical approaches. Until now, research on the cooling effect of MNF has focused mainly on heat propagation without any real magnetic system, in which the magnetic force plays a key role in driving fluidic flow. This flow driven by the magnetic force density was related to the magnetoconvection effect. To analyze this effect quantitatively, a coupled analysis technique should be developed using the magnetic-thermal-fluidic equations. To validate the cooling performance of MNFs numerically, the numerical results were verified by a comparison with those from the experimental tests in the air, transformer oil, and MNF. After confirming the numerical setup, some experiments were conducted with a vertical solenoid coil immersed in a MNF with different volume fractions of magnetic nanoparticles. The temperature at the inside part of the coil decreased dramatically by approximately 5^\circC in the 7 vol. % MNF compared to the transformer oil. These temperatures were also predicted well using the proposed numerical setup. [ABSTRACT FROM PUBLISHER]

High-power Stirling-type pulse tube coolers (HSPTCs) driven by oil-free linear compressors are promising candidates for cooling HTS devices for the advantages of simple configuration, low noise and stable operation. Three U-shaped two-stage pulse tube coolers driven by a 10 kW linear compressor were built and studied. The effects of flow inhomogeneity on the temperature profiles along the regenerator and on the cooling capacity were investigated experimentally. By optimizing the impedance matching and operating conditions, the first cooler can reach a base temperature of 44.2 K; the second cooler reaches a base temperature of 27.1 K and provides a cooling power of 50 W at 45.6 K with 4.8 kW of pV power; the last cold head reaches a base temperature of 13.27 K and provides a cooling power of 18.3 W at 30 K. The present results form a foundation for building a HSPTC system capable of providing a cooling power of 80 W at 30 K. [ABSTRACT FROM PUBLISHER]

The dimension of metallic current leads is optimized for minimizing the cooling load, taking into account the Ohmic heat generation of conductor part immersed in liquid nitrogen. Since HTS elements in liquid nitrogen are located well below the liquid level for thermal and electrical safety, considerable length of leads is in contact with liquid at constant temperature. In theory, the conductor size needs to be optimized for the upper part above the liquid surface, but a large cross-sectional area is favored for the lower part immersed in liquid in order to reduce the cooling load. On the other hand, this current-lead design aims at a simple metallic conductor with uniform cross-section for the entire length. It is rigorously shown that there exists a unique optimum for the total length-to-area ratio to minimize the overall cooling load, if the length fraction of liquid part is given. A new and useful design formula is derived upon the Wiedemann-Franz law for the temperature-dependent properties of conductor. [ABSTRACT FROM PUBLISHER]

Studies the performance of models constructed from metered residential central air conditioning loads. Load shape forecasting models; Comparison of the model results; Conclusions.