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Enteria N.,Tohoku University | Yoshino H.,Tohoku University | Mochida A.,Tohoku University | Satake A.,Maeda corporation | And 5 more authors.
Solar Energy | Year: 2012

This paper shows the numerical investigation of the developed solar-desiccant cooling system applied in the East Asian climatic conditions with two different desiccant wheel coating materials - the Silica-Gel (SiO 2) and the Titanium Dioxide (TiO 2). The developed and validated numerical model of the system is currently used in the present study incorporating the two new materials in the desiccant wheel. The system was applied in temperate climate (Beijing and Tokyo), subtropical climate (Taipei and Hong Kong) and tropical climate (Manila and Singapore). The study showed that the specification of the solar-desiccant cooling system varies depending on the climatic conditions. It showed that the required flat plate collector area was getting larger from the temperate climate to the tropical climate. The storage tank requirement was getting bigger in the tropical climate compared to the subtropical and temperate climate. The volumetric flow rate of air was getting higher from temperate climate to tropical climate. In the comparison of the two materials, it was found that the Titanium Dioxide (TiO 2) can support lower indoor temperature and humidity ratio than the Silica-Gel (SiO 2) with the same specification of the solar thermal system and desiccant cooling system. In general, the solar-desiccant cooling system can provide the required indoor temperature and humidity ratio. However, for the hot and humid climate such as in tropical, large size of the solar thermal system is needed. In addition, higher volumetric flow of air to support the high cooling load is required. With regard to the new material, Titanium Dioxide, it is proven to be a good alternative material since it can provide lower indoor temperature and humidity ratio with higher cooling performance than the Silica-Gel. © 2012 Elsevier Ltd. Source

Maruyama Y.,Maeda corporation | Tamura T.,Tokyo Institute of Technology | Okuda Y.,Japan Building Research Institute | Ohashi M.,Japan National Institute for Land and Infrastructure Management
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2012

CFD has come to be used in the prediction of wind loads by the development of computer. Wind loads acting on buildings located in turbulent boundary layer are affected by the characteristic of approach flow strongly. Because inflow wind fluctuations affect the results of calculation with CFD, various kinds of methods to generate inflow wind fluctuations are suggested. On the other hand in wind tunnel experiment, PIV (Particle image velocimetry) technology has improved and been able to catch the high frequency turbulent fluctuations. We can acquire time-dependent-data of three-dimensional wind velocity components directly by stereo PIV. This report presents the result of LES calculation of turbulent boundary layer developed on flat floor for inflow generation using stereo PIV measurement results, and we discuss the applicability and the utility of this method. The simulated results show that the turbulent boundary layer is formed and reaches the equilibrium state at a relatively short distance from the starting point of computation. It can be thought that this method is useful for reproducing a turbulent boundary layer by LES. © 2012 Elsevier Ltd. Source

Shang F.,Tsinghua University | An X.,Tsinghua University | Mishima T.,Maeda corporation | Maekawa K.,University of Tokyo
Journal of Advanced Concrete Technology | Year: 2011

Reinforcing bar corrosion induces splitting cracks in concrete along the bar axis and leads to bond deterioration. This can adversely affect the crack spacing in an RC member and have a serious effect on its serviceability. This study looks at axial nonlinearityin corroded RC members under tension and shows that fewer transverse cracks with greater spacing occur as steel corrosion progresses. The open-slip coupled model, which takes into account the transverse action associated with longitudinal bond stress transfer in the bond transition zone, is extended to cover corroded reinforcement and is successfully used to simulate the behavior of RC members in tension. Modeling of the bond transition zoneand of the layer of corrosion products is found to be crucial to understanding residual bond performance after corrosion has occurred. Copyright © 2011 Japan Concrete Institute. Source

Enteria N.,Tohoku University | Yoshino H.,Tohoku University | Satake A.,Maeda corporation | Mochida A.,Tohoku University | And 4 more authors.
Experimental Thermal and Fluid Science | Year: 2010

The experimental evaluation of the separated and coupled rotating desiccant wheel and heat wheel is reported. The study aims to investigate the performance of the desiccant wheel and of the heat wheel both when operated separately and jointly. The performance evaluation of the desiccant wheel is based on its moisture removal capacity (MRC), moisture removal regeneration (MRR), and moisture mass balance (MMB). In addition, the study used the total energy balance (TEB), sensible coefficient of performance (COPSensible), latent coefficient of performance (COPLatent) and, total coefficient of performance (COPTotal). The performance of the heat wheel is based on its effectiveness. The COPSensible, COPLatent and, COPTotal are used in the performance evaluation of the coupled desiccant wheel and heat wheel. The general results of the study show that the MRC, MRR and MMB coupled with the TEB, COPLatent, COPSensible and COPTotal predict adequately the performance of the desiccant wheel. In addition, the coupled operation of the desiccant wheel and heat wheel, contributed to the reduction of the external thermal energy requirement for the regeneration of the desiccant wheel. This study can be applied in other researches seeking evaluation of the desiccant wheel, heat wheel, and their combined operation. Moreover, the data presented here are significant for the desiccant wheel benchmarking and for evaluation of the desiccant wheel models. © 2009 Elsevier Inc. All rights reserved. Source

Shang F.,Tsinghua University | An X.,Tsinghua University | Kawai S.,Tsinghua University | Mishima T.,Maeda corporation
Computers and Concrete | Year: 2010

The bond mechanism for reinforcing bars in concrete is equivalent to the normal contact and friction between the inclined ribs and the surrounding concrete. Based on the contact density model for the computation of shear transfer across cracks, an open-slip coupled model was developed for simulating three-dimensional bond behavior for reinforcing bars in concrete. A parameter study was performed and verified by simulating pull-out experiments of extremely different boundary conditions: short bar embedment with a huge concrete cover, extremely long bar embedment with a huge concrete cover, embedded aluminum bar and short bar embedded length with an insufficient concrete cover. The bar strain effect and splitting of the concrete cover on a local bond can be explained by finite element (FE) analysis. The analysis shows that the strain effect results from a large local slip and the splitting effect of a large opening of the interface. Finally, the sensitivity of rebar geometry was also checked by FE analysis and implies that the open-slip coupled model can be extended to the case of plain bar. Source

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