Jpn. Soc. Atom. Env. 52(1): (2017)

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1 * 1 1 1, 2 1 Development of a Numerical Model for Predicting the Atmospheric Dispersion of Hydrogen-Sulfide Emitted from Geothermal Power Plants Hiroki Ono 1 *, Hiroshi Takimoto 1, Ayumu Sato 1, Takenobu Michioka 1, 2, Koichi Sada 1 1Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba , Japan 2Kindai University, 341 Kowakae, Higashi-Osaka-shi, Osaka , Japan *Corresponding author: ( ) h-ono@criepi.denken.or.p A numerical model for the environmental impact assessment of geothermal power plants was developed. The model was based on the Large Eddy Simulation (LES) that accurately takes into account the effects of plume rise, surrounding buildings and geophysical features. A new grid generation program for the LES was also included in the model. We carried out wind tunnel experiments to validate our numerical model. Based on the validation results, our numerical model represented the characteristics of the surface concentration obtained by the wind tunnel experiments. We concluded that our numerical model was applicable for the environmental impact assessment of geothermal power plants as an alternative to wind tunnel experiments. Key words : geothermal power plant, environmental impact assessment, large eddy simulation, complex terrain, atmospheric dispersion (Computational Fluid Dynamics CFD) 2. 1 (Large Eddy Simulation, LES)

20 J. Jpn. Soc. Atmos. Environ. Vol. 52 No. 1 2017 Fig. 1Computational region of the wind tunnel.

2 20 J. Jpn. Soc. Atmos. Environ. Vol. 52 No Fig. 1Computational region of the wind tunnel. LES kε (Tominaga and Stathopoulos, 2010) ( ) LES4 U x = 0 (1) Ui UU i 1 P Ui U τi + =- + ν t x ρ xi x + x x - i x +gi -β T- T (2) UC { 1 ( )} 0 γ C C Γ t + x = x x - x (3) UT T T α t + x = x x - x (4) U i i PCT ν Γ α gβ T 0 Eq. 23Eqs. 3, 42 Smagorinsky 1 1 U i U τi - τkkδi =- 2 νsgs Si, Si = x x (5) i SGS q ( ) 2 gi β T νsgs = Cs Δ 2Si Si + (6) Pr x ν C γ =- (7) x SGS Sc SGS SGS Pr SGS ν T q =- (8) x i Δ min(κy/c s, fv 1/3 ),f1exp(y /26) (9) Sc SGS SGSPr SGS SGS κ Vy 0.41 κy/c S fv 1/3 Eq. 6C s Smagorinsky 0.13Eq. 6 ν SGS 0 CFD OpenFOAM (ver. 2.3) filtered-linear TVD CrankNicolson PISO (Ono et al., 2015) (1/500) 2. 2 LES 10 m3 Fig. 13 z* (Fig. 2)

3 Cooling towers and other buildings represented in the computational region.

3 大気環境学会誌第 52 巻第 1 号 Fig. 2 Internal mesh aligning geophysical features. Fig. 3 Cooling towers and other buildings represented in the computational region. LES に有効であることが示されている (Ono et al., 2016) 電所構内の建屋を再現した (Fig. 3) 冷却塔や建屋の形状さらに上記プログラムで生成した 3 次元空間メッシュをデータは STL 形式 (Standard Triangulated Language) をサベースとして OpenFOAM に付属している計算格子生成ポートしており一般的な 3D-CAD ソフトなどから出力可ユーティリティである snappyhexmesh を用いて冷却塔や発能である

22 J. Jpn. Soc. Atmos. Environ. Vol. 52 No. 1 2017 Fig. 4A slope section to connect smoothly with the geophysical features in the wind-tunnel. 1 200 m2.5 m 1/500 5 mm 62.5 cm1.

4 22 J. Jpn. Soc. Atmos. Environ. Vol. 52 No Fig. 4A slope section to connect smoothly with the geophysical features in the wind-tunnel m2.5 m 1/500 5 mm 62.5 cm1.25 mm m (40 mm) 720 m10 m (20 mm) 10 m (20 mm) 2.5 m (5 mm) m (40 mm) (1979) Takimoto et al. (2015) PasquillGifford (Turner, 1970) D Briggs (Briggs, 1984) 1/ km1.5 km1.4 km 2 m 1 km 1 m (Fig. 4) 3. 2 AB2 2A (Fig. 5)W EW B WSWENE (Fig. 6)A

5212017 23 Fig. 5Geophysical features in the site A. Fig. 6Geophysical features in the site B. Table 1Specifications of the cooling towers. Table 1 A 21.2 mb 23.25 m 3.

5 Fig. 5Geophysical features in the site A. Fig. 6Geophysical features in the site B. Table 1Specifications of the cooling towers. Table 1 A 21.2 mb m 3. 3 Specification Site A Site B Number of fans 2 10 Layout of fans Straight Straight Diameter of fan 10.0 m 6.3 m Height 13.0 m 13.0 m Length of the long side 30.0 m m Exhaust wind speed 10.0 m/s 10.3 m/s Exhaust air temperature Summer K 7.4 K (against ambient air temperature) Winter K 34.2 K Table 2Experiment cases. Site Wind direction Season Wind speed A W Summer Mean Winter Mean E Summer Mean Winter Mean B WSW Summer Mean Winter Mean ENE Summer Mean 210 m A 5 m/s10 m/sb3.4 m/s10.7 m/s A2228B ENE26 (Table 2) 3. 4 Fig. 7AB

6 24 J. Jpn. Soc. Atmos. Environ. Vol. 52 No Fig. 7 ground concentrations (normalized by exhaust volume of tracer gas). B Fig. 8Normalized ground concentrations in the central axis of the plume (site: A, wind direction: W) Figs. 8, 9A 600 m W 150 m E100 m LES (Liu and Niu, 2016)E m 250 m Figs. 10, 11B WSW Fig. 9Normalized ground concentrations in the central axis of the plume (site: A, wind direction: E). 10ENE m A AB Fig. 12AW

7 Table 3FAC2 and FB of the ground concentrations in the central axis of the plume. Site Wind direction Season Wind speed FAC2 FB A W Summer Mean Winter Mean E Summer Mean Fig. 10Normalized ground concentrations in the central axis of the plume (site: B, wind direction: WSW). Winter Mean B WSW Summer Mean Winter Mean ENE Summer Mean Fig. 11Normalized ground concentrations in the central axis of the plume (site: B, wind direction: ENE). Fig. 13BWSW A B 50 m300 m Factor of two of observations (FAC2) Factor of two of observations (FAC2) n 1 if 0.5 Pi Oi FAC2 = Ni, Ni 1 if Oi W Pi W n = (10) i=1 0 else P i O i W Fractional bias (FB) Fractional bias (FB) O - P FB= (11) 0.5( O + P ) FB FB Table 3FAC2FB W 1 FAC AE FAC2 Fig. 14

26 J. Jpn. Soc. Atmos. Environ. Vol. 52 No. 1 2017 Fig. 12Surface distributions of normalized ground concentrations (site: A, wind direction: W). Fig. 13Surface distributions of normalized ground concentrations (site: B, wind direction: WSW).

8 26 J. Jpn. Soc. Atmos. Environ. Vol. 52 No Fig. 12Surface distributions of normalized ground concentrations (site: A, wind direction: W). Fig. 13Surface distributions of normalized ground concentrations (site: B, wind direction: WSW). Fig. 14Vertical profiles of normalized concentrations (site: A).

9 Table 4FAC2 and FB of ground concentration. Site Wind direction Season Wind speed FAC2 FB A W Summer Mean Winter Mean E Summer Mean Winter Mean B WSW Summer Mean Winter Mean ENE Summer Mean Fig. 14 FAC2 FB 0.3 Table 4FAC2FB W 1 2 AE FAC270 FB0.3European Cooperation in Science and Technology (COST) FAC20.54FAC20.89FB0.5 (Britter and Schatzmann, 2007)Chang and Hanna (2004) FB0.3 Fig. 15 A FAC2B 9 5. Fig. 15Comparison of the maximum ground con cen trations. CFD LES LES FAC2 10 CFD (RANS) RANSLES LES

10 28 J. Jpn. Soc. Atmos. Environ. Vol. 52 No LES 1/21/3 Briggs, G. A.: Atmospheric science and power production, United States Department of Energy, Chapter 8 (1984). Britter, R., Schatzmann, M.: Model Evaluation Guidance and Protocol Document, Cost Action 732, Quality Assurance And Improvement Of Micro-Scale Meteorological Models (2007). Chang, J. C., Hanna, S. R.: Air quality model performance evaluation, Meteorol. Atmos. Phys., 87, (2004). Liu, J., Niu, J.: CFD simulation of the wind environment around an isolated high-rise building: An evaluation of SRANS, LES and DES models, Build. Environ., 96, (2016). 12, (1979). (2015). Ono, H., Takimoto, H., Michioka, T., Sato, A.: Convection term discretization for large eddy simulations based on the finite volume method, effect of thermal stratification on the dispersion characteristics of rooftop exhaust, Part 2, J. Environ. Eng. (Trans. AIJ), 80, (2015) [in Japanese]. Ono, H., Takimoto, H., Michioka, T., Sato, A., Sada, K.: Large eddy simulation of atmospheric dispersion of cooling-tower exhaust over a simple shaped hill Validation of flow and dispersion field with different shaped grids, J. Jpn. Soc. Atmos. Environ., 51, (2016) [in Japanese]. CFD CFD (DiMCFD) (2013). Takimoto, H., Ono, H., Sato, A., Michioka, T., Sada, K.: A Wind-tunnel study of atmospheric dispersion of cooling-tower exhaust over a simple hill: Influences of plume rise and surface roughness of the terrain, J. Jpn. Soc. Atmos. Environ., 50, (2015) [in Japanese]. Tominaga, Y., Stathopoulos, T.: Numerical simulation of dispersion around an isolated cubic building: Model evaluation of RANS and LES, Build. Environ., 45, (2010). Turner, D. B.: Workbook of atmospheric dispersion estimates, Office of Air Programs Pub., AP-26, U.S. Environ-mental Protection Agency (1970)

11 * 1 1 1, (LES) LES

第６２巻　第１号　平成２４年４月／石こうを用いた木材ペレット

第６２巻　第１号　平成２４年４月／石こうを用いた木材ペレット Bulletin of Japan Association for Fire Science and Engineering Vol. 62. No. 1 (2012) Development of Two-Dimensional Simple Simulation Model and Evaluation of Discharge Ability for Water Discharge of Firefighting