- Email: [email protected]
Simulation of wave energy converter with designed pendulor-slope combination
Available online at www.sciencedirect.com Available online at www.sciencedirect.com
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Energyonline Procedia 00 (2018) 000–000 Available onlineatat www.sciencedirect.com Available www.sciencedirect.com Energy Procedia 00 (2018) 000–000
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www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Energy (2019) 000–000 733–737 EnergyProcedia Procedia158 00 (2017) www.elsevier.com/locate/procedia
10th International Conference on Applied Energy (ICAE2018), 22-25 August 2018, Hong Kong, 10th International Conference on Applied Energy China(ICAE2018), 22-25 August 2018, Hong Kong, China
Simulation of wave energy converter with designed pendulor-slope SimulationThe of 15th wave energy Symposium converteronwith International Districtdesigned Heating andpendulor-slope Cooling combination combination Assessing the heat demand-outdoor a, c, the feasibilitya of using Zhanhong Wana, c, *, Honghao Zhenga, Ke Sunbb, Dahai Zhangaa, Zhongzhi Yaoaa, Tianyu Zhanhong Wan function *, Honghaofor Zheng , Ke Suna , Dahai Zhang , Zhongzhi Yaoforecast , Tianyu temperature a long-term district heat demand Song a Song *, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre
OceanaCollege, Zhejianga University, Zhoushan b 316021, China c c b a The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science Technology, Wuhan 430081, China Ocean College, Zhejiang University, Zhoushan 316021,and China c b State Key Satellite OceanWuhan Environment Dynamics, Hangzhou 310012, China The State Key Laboratory of Laboratory Refractoriesofand Metallurgy, University of Science and Technology, Wuhan 430081, China a IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal c Stateb Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou 310012, China Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France
a,b,c
I. Andrić
a
Abstract Abstract Nowadays the global demand for energy is growing rapidly in China, which will be the world's largest country of energy Nowadays for energy is growing rapidly China, which will be renewable the world'swave largest country of energy consumption, is thus demand highly urgent to conduct the research andindevelopment of efficient energy equipment, e.g. Abstract theit global consumption, it is thus highly to conduct the to research and development of efficient renewable waveconditions energy equipment, e.g. wave energy converter (WEC).urgent So, this paper aims numerically develop a new WEC suitable for wave in Zhoushan wave energy converter (WEC). So, this paper aims to numerically develop a new WEC suitable for wave conditions in Zhoushan sea area. The specific research contents include the following aspects: (1) theoretic design by using the floating pendulum District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing to the sea area.the Thewave specific research contents include the These following aspects: (1) high theoretic design using floating pendulum to capture energy; (2) Computational Fluid Dynamics (CFD) simulation which is by based on 3-Dimensional unsteady greenhouse gas emissions from the building sector. systems require investments which arethe returned through the heat capture theAverage wave (2)climate Computational Fluid (CFD) simulation is basedofinon 3-Dimensional unsteady Reynolds Navier-Storkes (RANS) equations to analyzerenovation the hydrodynamic performance floating pendulor sales. Due to theenergy; changed conditions and Dynamics building policies,which heat demand the future couldcapturing decrease, Reynolds Average Navier-Storkes (RANS) equations to analyze the hydrodynamic performance of floating pendulor capturing wave energy. The initial design has been optimized to find the parameters of swing device floating in different output loads of prolonging the investment return period. wave energy. The designis has been optimized find the parameters of swing device temperature floating different of energy capture, and to recognize the conditions of thetodevice for subsequent energy systemindesign. The main scope ofinitial this paper to assess the feasibility of using the heat demand –conversion outdoor function output for heatloads demand energy capture, and to recognize the conditions of the device for subsequent energy conversion system design. forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 Copyright ©that 2018 Elsevier Ltd. All rights reserved. buildings vary in both construction period (low, medium, high) and three district © 2019 The Authors. Published by Elsevier Ltd. and typology. Three weather scenarios th International Conference on Applied Copyright © 2018 Elsevier Ltd. Allresponsibility rights reserved. Selection and peer-review under of the scientific committee of thethe10error, renovation scenarios were developed (shallow, intermediate, deep). To estimate obtained heat demand values were This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) th International Conference on Applied Selection and peer-review responsibility of the scientific committee of the 10 Energy (ICAE2018). compared with results fromunder a dynamic heat demand model, and validated byConference the authors. Peer-review under responsibility of the scientific committee ofpreviously ICAE2018developed – The 10th International on Applied Energy. Energy (ICAE2018). The results showed that when only weather change is considered, the margin of error could be acceptable for some applications Keywords: performance; wave energy converter; pendulor; CFD considered). However, after introducing renovation (the errorHydrodynamic in annual demand was lower than 20% for allfloating weather scenarios Keywords: Hydrodynamic performance; wave energy converter; floating pendulor; CFD
scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the 1.decrease Introduction in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and 1.renovation Introduction scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the As onescenarios). importantThe new energy for future all to over the world [1-3],parameters wave energy canscenarios be built considered, up over long coupled values suggested couldusage be used modify the function for the and As one new for future usageover all 100 over kW/m the world energy can be per builtmeter up over long improve theimportant accuracy heatenergy demand estimations. oceanic distances to of energy densities averaging (the [1-3], typicalwave measure is power width of
oceanic distances to energy densities averaging over 100 kW/m (the typical measure is power per meter width of © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +86-27-68862989; fax: +0-000-000-0000 .
address:author. [email protected] (Z. H. Wan); [email protected] (K. Sun) * E-mail Corresponding Tel.: +86-27-68862989; fax: +0-000-000-0000 . Keywords: Heat demand; Forecast; Climate change E-mail address: [email protected] (Z. H. Wan); [email protected] (K. Sun) 1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility the scientific 1876-6102 Copyright © 2018 Elsevier Ltd. All of rights reserved. committee of the 10th International Conference on Applied Energy (ICAE2018). Selection and peer-review under responsibility of the scientific committee of the 10th International Conference on Applied Energy (ICAE2018). 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. 1876-6102 © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of ICAE2018 – The 10th International Conference on Applied Energy. 10.1016/j.egypro.2019.01.196
734 2
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
wave front). The exploitable range limit could probably reach to 10–25% of the global resource, thus oceanic wave energy is a high potential energy contributor to mankind energy demands [4-7]. Therefore, the study of wave power generation is of significant prospects to improve China's environmental conditions and to promote social and economic development [8]. During the "Tenth Five-Year" period, China has paid attention to the wave of energy technology research and development. In the early stage, for instance, Guangzhou Institute of Energy has developed a number of low-power wave utilization device for the beacon power supply. Considering China’s sea conditions with uneven distribution, this paper aims to adopt numerical methods to develop and study a new WEC with combined Pendulor-Slope (realistic demonstration in Figure 1), which is suitable for wave conditions in Zhoushan sea area near one Zhejiang University campus [9]. In our study, the RANS method and VOF surface tracking method will be used to simulate the interaction between the wave and the combined Pendulor-Slope structure.
Fig. 1. A device system model of Type D with floating pendulor and a slope
Fig. 2 A cross-section of the computation mesh from the front view
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
735 3
2. Numerical Method The following paragraph describes the main frames and theoretic points of the simulation methods adopted in current work, and will analyze these computational techniques applied to present CFD model [10, 11]. The grid is generated using the automatic meshing function in STAR-CCM+ [12], resulting in a total of about 2 million cells of the computational grid with Trimmed Cells and Prism Layer Cells, as shown in Figure 2. The cutting body grid is used to produce high quality grids for complex grid generation problems. The free surface grid parameters are set according to the ship's CFD application guidelines for the International Towing Pool Meeting—ITTC [13]. The turbulent fluid model chosen in current work is a common k–ε model, which is being extensively adopted for engineering, environmental and industrial applications [12, 14]. For numerical scheme, the “Volume of Fluid” (VOF) method was utilized to simulate the free surface position and models, either with a flat/regular wave [15]. Figure 3 demonstrates the way the free surface was expressed in this CFD model by showing the profile of the water volume fraction on the hull.
P /W
Fig. 3. Simulation model and free surface representation of the “Volume of Fluid” (VOF) method
Fig. 4. Maximum instantaneous power output versus grid number (left Fig.: full scale; right one: enlarged view)
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Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
3. Results and discussion In this paper, the instantaneous power can represent the accuracy of the grid in the case of equal work time, and the instantaneous power value is a higher order function of the angular velocity. Therefore, the maximum instantaneous power is used to measure the accuracy of the modeling. As shown in Figure 4, it can be seen that the increase in the maximum power value of the grid is less than 0.5%. When the hydraulic cylinder is compressed, the pressure of the liquid in the cavity is constant. Therefore, the output power of the device under different constant load torque is studied in this paper. Take a constant moment 352kN.m for example, the specific simulation condition and results are: work time of maximum power is 2.1s; output power is around 44kW and output energy is 65.8 kJ. The instantaneous power curves are shown in Figure 5, which demonstrates the whole working process.
Fig. 5 Power curve at constant moment torque 352kN.m
4. Conclusion Based on the development of wave energy under the sea conditions near Zhoushan, China, this paper develops series of novel nearshore wave power generation devices with floating pendulum, and studies their hydrodynamic performance of wave energy capture. Numerical investigations are performed according to the designs. In the CFD study, RANS and DFBI models are adopted, and series of load performances are analyzed. For constant load torque conditions, there exists a maximum torque value above which the wave cannot drive the pendulum. Compared with the traditional WEC, floating pendulum-slope combined WEC has obvious advantages for nearshore sea conditions, including the designed Zhoushan sea areas. Acknowledgements The Support by the National Natural Science Foundation of China(Nos. 11572283, 11602179), National Key Research & Development Plan of China (No. 2016YFC1401603), Public Science and Technology Research Funds Projects of Ocean (No. 20110518-5) are all gratefully acknowledged.
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
737 5
References
[1] Kofoed JP, Frigaard P, Friis-Madsen E, Sørensen HC. Prototype testing of the wave energy converter wave dragon. Renewable Energy 2006;31:181-9. [2] Leybourne M, Batten WMJ, Bahaj AS, Minns N, O'Nians J. Preliminary design of the OWEL wave energy converter pre-commercial demonstrator. Renewable Energy 2014;61:51-6. [3] Budar K, Falnes J. A resonant point absorber of ocean-wave power. Nature. 1975;256:478-9. [4] Barstow S, Mørk G, Mollison D, Cruz J. The Wave Energy Resource. In: Cruz J., editor. Ocean Wave Energy: Current Status and Future Prespectives. Berlin, Heidelberg: Springer Berlin Heidelberg; 2008. p. 93-132. [5] Cruz J. Ocean wave energy: current status and future prespectives: Springer Science & Business Media; 2007. [6] Falcão AFdO. Modelling and control of oscillating-body wave energy converters with hydraulic power take-off and gas accumulator. Ocean Eng 2007;34:2021-32. [7] Fernandez H, Iglesias G, Carballo R, Castro A, Fraguela JA, Taveira-Pinto F, et al. The new wave energy converter WaveCat: Concept and laboratory tests. Marine Structures. 2012;29:58-70. [8] Wang CK, Lu DC, etc. Rural wave energy distribution in China. People's Republic of China: Department of Science and Technology, State Oceanic Administration; 1989. [9] Wan Z, Zheng H. A pendulor wave energy converter: ZL201420525951.6. 2014. [10] De Marco A, Mancini S, Miranda S, Scognamiglio R, Vitiello L. Experimental and numerical hydrodynamic analysis of a stepped planing hull. Appl Ocean Res 2017;64:135-54. [11] Sun K, Lu L, Jiang H. A numerical study of bend-induced particle deposition in and behind duct bends. Build Environ. 2012;52:77-87. [12] CD-Adapco. User guide STAR-CCM+ Version 10.0.6. 2016. [13] International Towing Tank Conference--ITTC. Practical guidelines for ship CFD applications. In: Proceedings of the 26th ITTC. 2011. [14] Demirel YK, Turan O, Incecik A. Predicting the effect of biofouling on ship resistance using CFD. Appl Ocean Res 2017;62:100-18. [15] López I, Pereiras B, Castro F, Iglesias G. Optimisation of turbine-induced damping for an OWC wave energy converter using a RANS–VOF numerical model. Appl Energy 2014;127:105-14.
ScienceDirect ScienceDirect
Energyonline Procedia 00 (2018) 000–000 Available onlineatat www.sciencedirect.com Available www.sciencedirect.com Energy Procedia 00 (2018) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Energy (2019) 000–000 733–737 EnergyProcedia Procedia158 00 (2017) www.elsevier.com/locate/procedia
10th International Conference on Applied Energy (ICAE2018), 22-25 August 2018, Hong Kong, 10th International Conference on Applied Energy China(ICAE2018), 22-25 August 2018, Hong Kong, China
Simulation of wave energy converter with designed pendulor-slope SimulationThe of 15th wave energy Symposium converteronwith International Districtdesigned Heating andpendulor-slope Cooling combination combination Assessing the heat demand-outdoor a, c, the feasibilitya of using Zhanhong Wana, c, *, Honghao Zhenga, Ke Sunbb, Dahai Zhangaa, Zhongzhi Yaoaa, Tianyu Zhanhong Wan function *, Honghaofor Zheng , Ke Suna , Dahai Zhang , Zhongzhi Yaoforecast , Tianyu temperature a long-term district heat demand Song a Song *, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre
OceanaCollege, Zhejianga University, Zhoushan b 316021, China c c b a The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science Technology, Wuhan 430081, China Ocean College, Zhejiang University, Zhoushan 316021,and China c b State Key Satellite OceanWuhan Environment Dynamics, Hangzhou 310012, China The State Key Laboratory of Laboratory Refractoriesofand Metallurgy, University of Science and Technology, Wuhan 430081, China a IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal c Stateb Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou 310012, China Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France
a,b,c
I. Andrić
a
Abstract Abstract Nowadays the global demand for energy is growing rapidly in China, which will be the world's largest country of energy Nowadays for energy is growing rapidly China, which will be renewable the world'swave largest country of energy consumption, is thus demand highly urgent to conduct the research andindevelopment of efficient energy equipment, e.g. Abstract theit global consumption, it is thus highly to conduct the to research and development of efficient renewable waveconditions energy equipment, e.g. wave energy converter (WEC).urgent So, this paper aims numerically develop a new WEC suitable for wave in Zhoushan wave energy converter (WEC). So, this paper aims to numerically develop a new WEC suitable for wave conditions in Zhoushan sea area. The specific research contents include the following aspects: (1) theoretic design by using the floating pendulum District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing to the sea area.the Thewave specific research contents include the These following aspects: (1) high theoretic design using floating pendulum to capture energy; (2) Computational Fluid Dynamics (CFD) simulation which is by based on 3-Dimensional unsteady greenhouse gas emissions from the building sector. systems require investments which arethe returned through the heat capture theAverage wave (2)climate Computational Fluid (CFD) simulation is basedofinon 3-Dimensional unsteady Reynolds Navier-Storkes (RANS) equations to analyzerenovation the hydrodynamic performance floating pendulor sales. Due to theenergy; changed conditions and Dynamics building policies,which heat demand the future couldcapturing decrease, Reynolds Average Navier-Storkes (RANS) equations to analyze the hydrodynamic performance of floating pendulor capturing wave energy. The initial design has been optimized to find the parameters of swing device floating in different output loads of prolonging the investment return period. wave energy. The designis has been optimized find the parameters of swing device temperature floating different of energy capture, and to recognize the conditions of thetodevice for subsequent energy systemindesign. The main scope ofinitial this paper to assess the feasibility of using the heat demand –conversion outdoor function output for heatloads demand energy capture, and to recognize the conditions of the device for subsequent energy conversion system design. forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 Copyright ©that 2018 Elsevier Ltd. All rights reserved. buildings vary in both construction period (low, medium, high) and three district © 2019 The Authors. Published by Elsevier Ltd. and typology. Three weather scenarios th International Conference on Applied Copyright © 2018 Elsevier Ltd. Allresponsibility rights reserved. Selection and peer-review under of the scientific committee of thethe10error, renovation scenarios were developed (shallow, intermediate, deep). To estimate obtained heat demand values were This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) th International Conference on Applied Selection and peer-review responsibility of the scientific committee of the 10 Energy (ICAE2018). compared with results fromunder a dynamic heat demand model, and validated byConference the authors. Peer-review under responsibility of the scientific committee ofpreviously ICAE2018developed – The 10th International on Applied Energy. Energy (ICAE2018). The results showed that when only weather change is considered, the margin of error could be acceptable for some applications Keywords: performance; wave energy converter; pendulor; CFD considered). However, after introducing renovation (the errorHydrodynamic in annual demand was lower than 20% for allfloating weather scenarios Keywords: Hydrodynamic performance; wave energy converter; floating pendulor; CFD
scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the 1.decrease Introduction in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and 1.renovation Introduction scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the As onescenarios). importantThe new energy for future all to over the world [1-3],parameters wave energy canscenarios be built considered, up over long coupled values suggested couldusage be used modify the function for the and As one new for future usageover all 100 over kW/m the world energy can be per builtmeter up over long improve theimportant accuracy heatenergy demand estimations. oceanic distances to of energy densities averaging (the [1-3], typicalwave measure is power width of
oceanic distances to energy densities averaging over 100 kW/m (the typical measure is power per meter width of © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. Tel.: +86-27-68862989; fax: +0-000-000-0000 .
address:author. [email protected] (Z. H. Wan); [email protected] (K. Sun) * E-mail Corresponding Tel.: +86-27-68862989; fax: +0-000-000-0000 . Keywords: Heat demand; Forecast; Climate change E-mail address: [email protected] (Z. H. Wan); [email protected] (K. Sun) 1876-6102 Copyright © 2018 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility the scientific 1876-6102 Copyright © 2018 Elsevier Ltd. All of rights reserved. committee of the 10th International Conference on Applied Energy (ICAE2018). Selection and peer-review under responsibility of the scientific committee of the 10th International Conference on Applied Energy (ICAE2018). 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. 1876-6102 © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of ICAE2018 – The 10th International Conference on Applied Energy. 10.1016/j.egypro.2019.01.196
734 2
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
wave front). The exploitable range limit could probably reach to 10–25% of the global resource, thus oceanic wave energy is a high potential energy contributor to mankind energy demands [4-7]. Therefore, the study of wave power generation is of significant prospects to improve China's environmental conditions and to promote social and economic development [8]. During the "Tenth Five-Year" period, China has paid attention to the wave of energy technology research and development. In the early stage, for instance, Guangzhou Institute of Energy has developed a number of low-power wave utilization device for the beacon power supply. Considering China’s sea conditions with uneven distribution, this paper aims to adopt numerical methods to develop and study a new WEC with combined Pendulor-Slope (realistic demonstration in Figure 1), which is suitable for wave conditions in Zhoushan sea area near one Zhejiang University campus [9]. In our study, the RANS method and VOF surface tracking method will be used to simulate the interaction between the wave and the combined Pendulor-Slope structure.
Fig. 1. A device system model of Type D with floating pendulor and a slope
Fig. 2 A cross-section of the computation mesh from the front view
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
735 3
2. Numerical Method The following paragraph describes the main frames and theoretic points of the simulation methods adopted in current work, and will analyze these computational techniques applied to present CFD model [10, 11]. The grid is generated using the automatic meshing function in STAR-CCM+ [12], resulting in a total of about 2 million cells of the computational grid with Trimmed Cells and Prism Layer Cells, as shown in Figure 2. The cutting body grid is used to produce high quality grids for complex grid generation problems. The free surface grid parameters are set according to the ship's CFD application guidelines for the International Towing Pool Meeting—ITTC [13]. The turbulent fluid model chosen in current work is a common k–ε model, which is being extensively adopted for engineering, environmental and industrial applications [12, 14]. For numerical scheme, the “Volume of Fluid” (VOF) method was utilized to simulate the free surface position and models, either with a flat/regular wave [15]. Figure 3 demonstrates the way the free surface was expressed in this CFD model by showing the profile of the water volume fraction on the hull.
P /W
Fig. 3. Simulation model and free surface representation of the “Volume of Fluid” (VOF) method
Fig. 4. Maximum instantaneous power output versus grid number (left Fig.: full scale; right one: enlarged view)
736 4
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
3. Results and discussion In this paper, the instantaneous power can represent the accuracy of the grid in the case of equal work time, and the instantaneous power value is a higher order function of the angular velocity. Therefore, the maximum instantaneous power is used to measure the accuracy of the modeling. As shown in Figure 4, it can be seen that the increase in the maximum power value of the grid is less than 0.5%. When the hydraulic cylinder is compressed, the pressure of the liquid in the cavity is constant. Therefore, the output power of the device under different constant load torque is studied in this paper. Take a constant moment 352kN.m for example, the specific simulation condition and results are: work time of maximum power is 2.1s; output power is around 44kW and output energy is 65.8 kJ. The instantaneous power curves are shown in Figure 5, which demonstrates the whole working process.
Fig. 5 Power curve at constant moment torque 352kN.m
4. Conclusion Based on the development of wave energy under the sea conditions near Zhoushan, China, this paper develops series of novel nearshore wave power generation devices with floating pendulum, and studies their hydrodynamic performance of wave energy capture. Numerical investigations are performed according to the designs. In the CFD study, RANS and DFBI models are adopted, and series of load performances are analyzed. For constant load torque conditions, there exists a maximum torque value above which the wave cannot drive the pendulum. Compared with the traditional WEC, floating pendulum-slope combined WEC has obvious advantages for nearshore sea conditions, including the designed Zhoushan sea areas. Acknowledgements The Support by the National Natural Science Foundation of China(Nos. 11572283, 11602179), National Key Research & Development Plan of China (No. 2016YFC1401603), Public Science and Technology Research Funds Projects of Ocean (No. 20110518-5) are all gratefully acknowledged.
Zhanhong Wan et al. / Energy Procedia 158 (2019) 733–737 Author name / Energy Procedia 00 (2018) 000–000
737 5
References
[1] Kofoed JP, Frigaard P, Friis-Madsen E, Sørensen HC. Prototype testing of the wave energy converter wave dragon. Renewable Energy 2006;31:181-9. [2] Leybourne M, Batten WMJ, Bahaj AS, Minns N, O'Nians J. Preliminary design of the OWEL wave energy converter pre-commercial demonstrator. Renewable Energy 2014;61:51-6. [3] Budar K, Falnes J. A resonant point absorber of ocean-wave power. Nature. 1975;256:478-9. [4] Barstow S, Mørk G, Mollison D, Cruz J. The Wave Energy Resource. In: Cruz J., editor. Ocean Wave Energy: Current Status and Future Prespectives. Berlin, Heidelberg: Springer Berlin Heidelberg; 2008. p. 93-132. [5] Cruz J. Ocean wave energy: current status and future prespectives: Springer Science & Business Media; 2007. [6] Falcão AFdO. Modelling and control of oscillating-body wave energy converters with hydraulic power take-off and gas accumulator. Ocean Eng 2007;34:2021-32. [7] Fernandez H, Iglesias G, Carballo R, Castro A, Fraguela JA, Taveira-Pinto F, et al. The new wave energy converter WaveCat: Concept and laboratory tests. Marine Structures. 2012;29:58-70. [8] Wang CK, Lu DC, etc. Rural wave energy distribution in China. People's Republic of China: Department of Science and Technology, State Oceanic Administration; 1989. [9] Wan Z, Zheng H. A pendulor wave energy converter: ZL201420525951.6. 2014. [10] De Marco A, Mancini S, Miranda S, Scognamiglio R, Vitiello L. Experimental and numerical hydrodynamic analysis of a stepped planing hull. Appl Ocean Res 2017;64:135-54. [11] Sun K, Lu L, Jiang H. A numerical study of bend-induced particle deposition in and behind duct bends. Build Environ. 2012;52:77-87. [12] CD-Adapco. User guide STAR-CCM+ Version 10.0.6. 2016. [13] International Towing Tank Conference--ITTC. Practical guidelines for ship CFD applications. In: Proceedings of the 26th ITTC. 2011. [14] Demirel YK, Turan O, Incecik A. Predicting the effect of biofouling on ship resistance using CFD. Appl Ocean Res 2017;62:100-18. [15] López I, Pereiras B, Castro F, Iglesias G. Optimisation of turbine-induced damping for an OWC wave energy converter using a RANS–VOF numerical model. Appl Energy 2014;127:105-14.