Computational Fluid Dynamics (hereafter, CFD) is one of the most useful techniques to predict the airflow distribution in air-conditioned and ventilated rooms. The previous studies show that the prescribed velocity method (hereafter, P. V. method) is effective to simulate complicated airflow from an air diffuser in CFD. However, the velocity distribution in the vicinity of the air diffuser as boundary conditions of coarse gird CFD using P. V. method can be affected by the airflow rate, the connecting conditions of the diffuser and supply air duct, and the buoyancy effect due to the temperature distribution. In this paper, the development of the versatile airflow data for P. V. method and the method for its application are discussed. In the first study, the unstructured fine elements CFD simulations under isothermal condition are carried out and the obtained airflow distributions of the system ceiling air diffuser are compared. The relationship between the airflow rate and the velocity near the diffuser, the influence of connecting conditions of the diffuser and air duct are confirmed by the comparison of CFD results. In the second study, the influence of the buoyancy near the diffuser is compared to the inertial force of discharged air on the basis of local Archimedes number obtained by the unstructured CFD simulations under non-isothermal condition.

The previous studies show that the prescribed velocity method (hereafter, P. V. method) is effective to simulate complicated airflow from an air diffuser in CFD. However P.V. method is not applied to system ceiling air diffusers which are popular in office buildings. In this paper, the unstructured fine mesh CFD is conducted to obtain the airflow data of four types of system ceiling diffuser. Then the airflow data is applied in the structured coarse mesh CFD and the short circuit rate and the normalized concentration of occupied zone are examined as ventilation effectiveness. The relationship between shape of diffuser and ventilation effectiveness is discussed on the basis of CFD results.

In order to save energy consumption for air-conditioning of buildings throughout those lifecycle, thermal performance of insulation materials applied in buildings should be kept in required value. On the other hand, there are many factors of ageing of insulation materials such as ambient temperature, vibration and moisture etc. In the previous paper, main factors of thermal performance change were discussed and several experimental results were shown. This paper examines the influences of moisture on thermal performance of various insulations based on three kinds of experiment. In first experiment, the relationship between equilibrium moisture content and thermal conductivity of fiber insulations is obtained. Second experiment is on the influence of gaseous moisture on fiber insulations and the results show that the dimension change of fiber insulations is small even in very humid condition. Third experiment is on the reversibility of thermal conductivity after the internal dew condensation process and the dry process, and the results show that many insulation materials have reversibility except for several plastic insulation foams.

Thermal performance of insulation materials decreases with the passage of time. Such ageing of insulations should be considered in the design stage of buildings to keep insulation performance within the required one throughout the lifecycle of buildings. Firstly this paper focused various factors that affect performances of insulations. The main factors for fiber insulations are moisture vibration and microbe. The main factor for plastic insulation foams is ambient temperature that accelerates the diffusion of blowing agent. Secondly real performances of sold new insulations and scraped old ones were measured and compared the required value by Japanese standard. Performances of some insulations were lower than standard values and performance change was detected. Finally this paper discussed the influence of vibration on performance for fiber insulations based on the experimental data. The changes of insulation depth and thermal resistances were observed after the vibration test.

CFD技術を用いた室内の流れ場・温度場や汚染質拡散場の不均一分布予測は、パーソナルコンピュータの高性能化・高速化と汎用的な熱流体解析ソフトの普及によって実務での使用が一般的となっている。1990年代初頭より汎用CFDソフトウェアを用いた室内環境解析の事例報告が顕著となり、近年では複雑な幾何形状を対象とした解析はほぼ市販の汎用CFDソフトウェアによって実施されているといっても過言ではない状況である。本報では、室内環境設計や空気調和設備設計の実務において採用の事例がある各種の汎用CFDソフトウェアの特徴を整理すると共に、平均流や乱流統計量に関して詳細な実験データの存在する2次元居室モデルを対象としてベンチマークテストを実施した結果を紹介し、室内環境設計の実務に汎用CFDソフトウェアを使用する際の注意事項を整理する。

The insulation materials are used to improve thermal performance of buildings and their performance should be kept in required value during building life time, however long term change of thermal conductivity is observed for most of insulation materials. It is well known that the thermal conductivity of insulation foams increases with time due to the emission of the blowing agents from the insulation foams and the transfer of the air into them. In this paper, the aging of thermal conductivity in various insulation foams is discussed with measured data and numerical analysis. Two kinds of accelerated test are conducted and the aging characteristics of various foams are examined. The estimation equations of thermal conductivity change of insulation foams are shown and applied to the measured materials. The effective diffusion coefficient of the blowing agents is obtained by comparing the simulation results and the measured value.

The diffusion of the blowing agents in the building insulation foams and the transfer of the air into the insulation foams cause the decrease of the thermal insulation performance. In order to evaluate the protection effectiveness of global warming for the long term, it is important to estimate the aging of the thermal conductivity in the building insulation foams. In this paper, the aging of thermal conductivity in building insulation foams using fluorocarbons or hydrocarbons as the blowing agents was discussed with measured data and numerical analysis. The equations to estimate the thermal conductivity in insulation foams were expressed and the measured data of the thermal conductivity in polyurethane foam and polystyrene foam were represented. The several numerical simulations using these equations were conducted. The calculated thermal conductivity was compared to the measured value and the calculated results showed the good agreement with the measured data. The decay of the partial pressure of the blowing agents was calculated with numerical simulation and the thermal conductivity in the insulation foams increased because the partial pressure within the insulation foams was decreased and the total pressure became the atmospheric pressure.

Problems in indoor air quality (IAQ) are considered to cause "Sick House Syndrome" in Japan. As such, the building standard was revised to improve IAQ in rooms in Japan in 2003. It is also very important to ventilate indoor spaces efficiently to reduce energy and CO_2 consumption. Ventilation efficiency indexes have been proposed as a means to evaluate the efficiency of ventilation systems and these indexes have been taken into account in ventilation design. This paper proposes the effective ventilated volume as a ventilation efficiency index and gives a definition for the equation of the effective ventilated volume based on the volume integral with a weighting function. The meaning of the effective ventilated volume depends on the selected weighting function, therefore different forms of the weighting function are examined. Three functions are chosen to express the effective ventilated volume for a volume in a well-ventilated zone compared to that in a perfect mixing condition. The weighting functions are described with the local age of air, and the volume of the zone is either neglected or reduced in evaluating the effective ventilated volume when the local age of air is larger than the nominal time constant, i.e. the age of air under the perfect mixing condition. 2-D case studies on the effective ventilated volume based on computation fluid dynamics (CFD) are demonstrated.

低温送風空調方式を適用した室内の温熱・空気環境の検討は、これまで実験や実測により多く行われているが、CFD解析による詳細な検討例は少ない。これは複雑な吹出口からの気流性状をCFD解析で再現するには膨大な計算時間が必要となることなどが理由として挙げられる。本研究では、高拡散型吹出口を対象にCFD解析におけるモデリングを検討する。まず、高拡散型吹出口を設置した実験室において非等温実験を行い、室内の気流・温度分布を測定する。次に、非構造格子系CFD解析(等温場)により吹出気流データを作成し、このデータを用いたP.V.法によりCFD解析を行い、比較的粗いメッシュ分割のCFD解析においても実験結果を再現できることを示す。

The amount of fluorocarbons involved in building insulation foams as blowing agents is discussed with numerical analysis and measured data in this paper. The diffusion process of fluorocarbons in insulation foams can be expressed as a simple one dimensional diffusion equation. Effective diffusivity and initial concentration of CFCs and HCFCs are necessary to calculate the decrease of concentration with the analytical solution of the diffusion equation. The initial concentration can be obtained from the information of manufactures. In order to study the effective diffusivity, the calculated concentration of CFCs and HCFCs is compared to the measured data. Many samples were collected in various areas in Japan and their CFCs and HCFCs concentrations were measured by the gas chromatography method. The emission rate of CFCs and HCFCs was estimated by the analytical solutions with the effective diffusivity and initial concentration and the database of remained volume for various ages and areas is obtained in this paper. The total amount of CFCs and HCFCs can be estimated with this database and another database of the building insulation stock that will be discussed in Part 2.

In the previous papers, the P. V. Method (Prescribed Velocity Method : P. V. Nielsen et al. : 1980) was applied to the coarse grid CFD simulations with the isothermal and non-isothermal airflow data obtained by the experiments. The simulated results showed good agreement with the experimental ones. If the effect of the buoyancy is smaller than that of the kinetic energy around the ceiling air diffuser, the airflow data obtained under isothermal condition can give the boundary condition for the coarse grid non-isothermal CFD using the simplified modeling method. The possibility of the application of the isothermal airflow data to the non-isothermal CFD simulation was examined in this paper. The eftect of the buoyancy in the vicinity of the ceiling air diffuser was compared to that of the kinetic energy by calculating local Archimedes number. When the virtual box around the air diffuser was small, the local Archimedes number at the box surface were much lower than 0.1 and the buoyancy effect was not significant. The CFD simulation using the P. V. method with the small virtual box based on the isothermal airflow data was carried out and compared to the experiment. The CFD can reproduce the distributions of the airflow and temperature obtained by the experiment. Therefore it was concluded in this paper that the isothermal airflow data can be applied to the non-isothermal CFD simulation under the certain conditions.

In the previous paper, measurements were carried out in a test room in which a complex ceiling air diffuser was installed, and coarse arid CFD was conducted using the Box method (P. V. Nielsen et al.; 1978, 1992) and the Prescribed Velocity Method (P. V. Nielsen et al; 1980) based on the boundary airflow data obtained by the experiment. The results of the CFD using these methods showed good agreement with the measured value. In this paper, CFD simulation using the unstructured fine elements system was applied to obtained airflow data around a air diffuser as boundary conditions of coarse grid CFD. The unstructured CFD simulation reproduced the measured airflow distribution in the room and gave the boundary conditions for complex air diffuser with much less effort than by the experiment. It was also confirmed that coarse grid CFD using P. V Method with boundary airflow data obtained by the unstructured CFD gave good results.

屋内アイスアリーナにおける換気設備は主として観客を対象として計画されている。しかし実際には競技者のほうが空気汚染に対して敏感であることが確認されている。本研究では、屋内アイスアリーナ内の空気汚染源のひとつとして考えられる整氷車からの排ガスに着目し、排ガス内に含まれる汚染物質を測定し、またアイスリンク面上や観客席の空気質について調査する。さらに数値流体解析により屋内アイスアリーナ内の空気質を改善する方法について検討する。

In the previous paper, Part 1, the full scale experiment of airflow distribution in a room was carried out under isothermal condition. With the airflow data obtained by the measurement, the BOX method and the P. V. method (the prescribed velocity method) were applied to the CFD simulation. The simulated results showed good agreement with the experimental ones not only around the diffuser but also the other part of the room. This paper presents the full scale experiment and the application of the coarse grid CFD simulation using the P. V. method under non-isothermal condition. In the full scale experiments, the detail of the airflow and temperature distributions around a complex air diffuser installed at the ceiling were obtained. The coarse grid CFD simulation with the P. V. method based on the airflow distribution around the diffuser obtained by the measurement was carried out. The results of this simulation reproduced the complex airflow distributions that were observed in the measurements, such as the attached air jet horizontally along the ceiling, the vertical downward free jet and the induced flow near the diffuser. The simulated temperature distributions of the room air and the wall surfaces also agreed with thc measured ones.

Computational Fluid Dynamics (CFD) is one of the most useful techniques to predict the air distribution in air-conditioned and ventilated rooms. The supply airflow such as free jet, wall jet and combined flow of these jets has a great influence on the air distribution in rooms. Most of supply air diffusers have complex geometry, however, the shape of diffuser is usually oversimplified in CFD with coarse grids system. The results of such simulation may give incorrect prediction due to the poor modeling of diffusers. Even if the complex geometry of air diffuser can be described in detail, huge computer capacity and very long calculation time were required. In this paper, several modeling methods to simplify the boundary condition around air diffusers, such as BOX Method (P.V. Nielsen; 1976,1992) and P.V. Method (Prescribed Velocity Method, P.V. Nielsen et al.; 1980), are compared. These modelings require the distribution of air velocity, turbulence properties, temperature and concentrations around the diffuser beforehand. These data as the boundary condition for CFD with coarse grids can be obtained from the experimental measurement or the unstructured CFD simulation with fine meshes. In this paper, the full scale experiment was carried out at isothermal condition, and the airflow data around complex air diffuser installed at ceiling was obtained. With the basis of the flow data around the diffuser by the measurement, BOX Method and P.V. Method were applied to the air diffuser. The results of coarse grids CFD showed the good agreement not only around diffusers but in other part of rooms with the measurement.

This paper describes the simulation method of the indoor humidity and temperature distributions that is important to study the wet area in rooms. (1) Buoyancy Effect of Humidity Ratio The air density depends not only on temperature but on mass concentration such as humidity, therefore the buoyancy effect of humidity may be appeared in some spaces where the spatial distribution of humidity is very large. The treatment method of this effect into the k-ε turbulence model was discussed in this paper. (2) Near Wall Mass Transfer In order to study the airflow and humidity distributions near wall region, the two-dimensional cavity flows was simulated based on the Low-Reynolds number k-ε model.

建物外被の熱的性能を向上させる一つの方法として日射反射率の高い塗料(以後,高反射率塗料と記す)を塗布し,建物外被が受ける日射熱量を軽減する方法が考えられる.本報では模型実験および熱負荷計算により高反射率塗料の省エネルギー効果を検討した.また各種の建物に適用した場合の熱負荷軽減効果などを算定した.さらに高反射率塗料を建物外被に塗布した場合,都市部の日射吸収量が軽減し,ヒートアイランド現象が緩和される可能性についても都市の一次元熱収支モデルを用いて示した.

The previous studies show that P. V. method is effective to simulate complicated airflow from an air diffuser in CFD. However P. V. method is not applied to system ceiling air diffusers which are popular in office buildings. In this paper, the unstructured fine mesh CFD is conducted to obtain the airflow data of four types of system ceiling diffuser. Then the airflow data is applied in the structured coarse mesh CFD and the short circuit rate and the normalized concentration of occupied zone are examined as ventilation effectiveness. The relationship between shape of diffuser and ventilation effectiveness is discussed on the basis of CFD results.

Several types of ceiling air diffuser form the attached air jet along the ceiling which diffuses throughout a room. However, if the layout of supply openings and exhaust ones is not appropriate, the short circuit between them appears and ventilation/air-conditioning efficiency becomes very low. In this paper, CFD simulation method of Short Circuit is examined and effect of short circuit on indoor thermal environment and IAQ is studied.

Under floor air conditioning system (hereafter UFAC) has become popular in Japan, because it is effective to save energy for HVAC. However UFAC may cause uncomfortable drought due to unsuitable layout and/or inadequate supplied air velocity of air diffuser. In order to resolve such problems, airflow and temperature distributions should be predicted precisely. In this paper, CFD modeling of air diffuser for UFAC is studied based on measured data. The simulated indoor environment by CFD with air diffuser model is compared with the experimental results and good agreement is confirmed.

In large enclosures such as gymnasiums, it is difficult to control air temperature in the occupied zone comfortable in heating condition. There are two main reasons why air temperature in an occupied area is not increased efficiently in large enclosures. 1) A hot supplied air goes up and stays upper area due to buoyancy and it takes long time to reach lower occupied area. 2) Heat capacity of building structure disturbs to increase air temperature and cold air stays lower area. In this paper, the field measurement is presented in which the under floor return system is applied to the gymnasium to resolve these problems. Macroscopic simulation and CFD simulation are also demonstrated and the details of temperature distributions and during warming up are discussed.

1.本研究で開発するシミュレーションプログラムに必要な物性値である日射反射率と放射率に関しては以下の成果を得た。 (1)レースカーテンの日射透過率を、屋外での日射計による測定と実験室での積分球による測定により求め、両者がほぼ一致することを確認した。 (2)各種塗料の日射反射率を測定した。その結果、多くの高反射性塗料で、赤外域の反射率が通常の塗料より高いことが確認された。 (3)通気層表面の低放射膜及び各種建築材料の放射率を、恒温室でサーモトレーサを用いて測定した。 2.シミュレーションプログラムの開発に関しては以下の成果を得た。 (1)住宅熱環境シミュレーションプログラムREESTの基本形を作成した。 (2)REESTコアプログラムの仕様書を作成した。 (3)REEST用入力データとしてカタログデータの概念を導入し、住宅を類別化して数種類のカタログデータを作成した。 (4)shadewall(通気外壁・屋根の計算を行うプログラム)をREESTに組み込んだ。 (5)WindEye(窓の断熱・遮熱性の評価ツール)をREESTに組み込む方法を検討した。 (6)REESTに組み込む太陽電池のシミュレーションツールを開発した。 (7)REESTに室湿度変動の計算法を組み込むための基礎的な検討を行った。