Please use the "Contact" page of the menu, we will remove the document as soon as possible (please allow us at least one week to act. Thank you.)

Solar Energy, Volume 80, Issue 11, November 2006, Pages 1417-1423

Theodor W. von Backström, Thomas P. Fluri

Main features of a solar chimney power plant are a circular greenhouse type collector and a tall chimney at its centre. Air flowing radially inwards under the collector roof heats up and enters the chimney after passing through a turbo-generator.

The objective of the study was to investigate analytically the validity and applicability of the assumption that, for maximum fluid power, the optimum ratio of turbine pressure drop to pressure potential (available system pressure difference) is 2/3. An initial power law model assumes that pressure potential is proportional to volume flow to the power m, where m is typically a negative number between 0 and −1, and that the system pressure drop is proportional to the power n, where typically n = 2. The analysis shows that the optimum turbine pressure drop as fraction of the pressure potential is (n − m)/(n + 1), which is equal to 2/3 only when m = 0, implying a constant pressure potential, independent of flow rate. Consideration of a basic collector model proposed by Schlaich leads to the conclusion that the value of m is equal to the negative of the collector floor-to-exit efficiency. A more comprehensive optimization scheme, incorporating the basic collector model of Schlaich in the analysis, shows that the power law approach is sound and conservative.

It is shown that the constant pressure potential assumption (m = 0) may lead to appreciable underestimation of the performance of a solar chimney power plant, when compared to the analyses presented in the paper. More important is that both these analyses predict that maximum fluid power is available at much lower flow rate and much higher turbine pressure drop than predicted by the constant pressure potential assumption. Thus, the constant pressure potential assumption may lead to overestimating the size of the flow passages in the plant, and designing a turbine with inadequate stall margin and excessive runaway speed margin. The derived equations may be useful in the initial estimation of plant performance, in plant performance analysis and in control algorithm design. The analyses may also serve to set up test cases for more comprehensive plant models.

Article Outline

Nomenclature

1. Introduction

2. Power law model

2.1. Maximum fluid power condition

3. Value of m for simple solar collector model

3.1. Power law vs. constant pressure potential model

4. Effect of variable collector efficiency

5. Conclusions

References

Solar Energy, Volume 80, Issue 5, May 2006, Pages 535-544

J.P. Pretorius, D.G. Kröger

This paper evaluates the influence of a recently developed convective heat transfer equation, more accurate turbine inlet loss coefficient, quality collector roof glass and various types of soil on the performance of a large scale solar chimney power plant. Results indicate that the new heat transfer equation reduces plant power output considerably. The effect of a more accurate turbine inlet loss coefficient is insignificant, while utilizing better quality glass enhances plant power production. Models employing Limestone and Sandstone soil produce virtually similar results to a Granite-based model. The plant collector height is found to differ from previously obtained optimal values.

Article Outline

Nomenclature

1. Introduction

2. Convective heat transfer equation

2.1. Convection to ambient

2.2. Convection from roof to collector air

2.3. Convection from ground to collector air

2.4. Simulation and results

3. Turbine inlet loss coefficient

3.1. Simulation and results

4. Collector roof glass quality

4.1. Simulation and results

5. Various ground types

5.1. Simulation and results

6. Optimizing the collector roof shape and inlet height

6.1. Simulation and results

7. Conclusion

Appendix A

References

Fuel, Volume 85, Issues 17-18, December 2006, Pages 2561-2566

Frederick N. Onyango, Reccab M. Ochieng

Solar chimney electric power generation is one of the concepts in renewable energy technology (RET) application. The power station is based simply on the principle that warm air rises. Air underneath a glass ceiling is heated by solar radiation and rises through a chimney. The warm air which has just risen is replaced by air from the edge of the glass ceiling which flows inward, and will then itself begin to heat up. In this way the Sun’s heat radiation is converted into kinetic energy of constantly rising air to drive turbine built into the chimney. The turbine then converts the wind power by means of a generator into electrical energy. We have considered the appropriateness of a solar chimney to rural villages and highlight some features of such a power generating plant. The calculations carried out show that the power that can be generated by a solar chimney of specific dimension exhibit a minimum threshold value of τ = 2.9, the temperature ratio of the difference between the collector surface temperature and the temperature at the turbine (Ts–TH) to the difference between the air mass temperature under the roof and the collector surface temperature (Tm–Ts). Our calculations show that for τ = 2.9, an appreciable electric power ( 103 W) can be generated by a sturdy and physically viable solar chimney whose dimension has been determined to be L = 150 m, H = R = 1.5 m. Thus the minimum dimension of a practical solar chimney electric power station would serve approximately fifty (50) households in a typical rural setting.

Article Outline

Nomenclature

1. Introduction

2. Solar chimney

3. Theory

4. Discussion

5. Conclusion

References

Renewable Energy, Volume 31, Issue 12, October 2006, Pages 1873-1891

F. Denantes, E. Bilgen

An efficiency model at design performance for counter-rotating turbines is developed and validated. Based on the efficiency equations, an off-design performance model for counter-rotating turbines is developed. Combined with a thermodynamic model for a solar chimney system and a solar radiation model, annual energy output of solar chimney systems is determined. Two counter-rotating turbines, one with inlet guide vanes, the other without, are compared to a single-runner system. The design and off-design performances are weighed against in three different solar chimney plant sizes. It is shown that the counter-rotating turbines without guide vanes have lower design efficiency and a higher off-design performance than a single-runner turbine. Based on the output torque versus power for various turbine layouts, advantageous operational conditions of counter-rotating turbines are demonstrated.

Article Outline

Nomenclature

1. Introduction

2. Counter-rotating turbines

2.1. Mathematical model

2.2. Profile loss model

2.2.1. Constant profile loss model

2.2.2. Profile loss model by Lewis

2.2.3. Profile loss model using lift/drag ratio

2.3. Validation and comparison of the loss models

2.3.1. Single-runner turbine

2.3.2. Counter-rotating turbine

2.3.3. Comparison of the three profile loss models

2.4. Design performance model

3. Solar chimney model

3.1. Thermodynamics

4. Solar radiation

5. Results and discussion

5.1. Scenarios

5.2. Mechanical considerations

5.3. Torque comparison with SRT, CRT, and CRTa turbines

5.4. Nominal turbine efficiency

5.5. Off-design performance

5.6. Efficiency

5.7. Annual energy output

6. Conclusions

Acknowledgements

References

Solar Energy, Volume 80, Issue 7, July 2006, Pages 804-811

Solar chimneys are defined as low temperature solar thermal power plants, which use the atmospheric air as a working fluid, where only one part of the thermodynamic cycle within the plant is utilized. The available work potential that atmospheric air acquires while passing through the collector has been determined and analyzed. The dependence of the work potential on the air flowing into the air collector from the heat gained inside the collector, air humidity and atmospheric pressure as a function of elevation are determined. Various collector types using dry and humid air have been analyzed. The influence of various chimney heights on the air work potential are established. The possibly higher utilization factors of the available hot air work potential without the use of high solid chimneys are discussed. It has been shown that the vortex motion flowing downstream of the turbine can be maintained under pressure and can possibly take over the role of the solid structure chimney. Thus, a part of the available energy potential acquired in the collector would be used to maintain the vortex flow in the air column above the ground-level turbine. Basic conditions for the maintenance of such a vortex flow are described and compared to the tornado phenomenon.

Article Outline

Nomenclature

1. Introduction

2. Available energy of the collector air

3. Height potential in the standard atmosphere

4. The role of the solid chimney

5. The impact of humidity on the height potential

6. The possibility of ground-level concentration of the height potential

7. Conclusion

Acknowledgements

References

.

2006

集热棚对太阳能烟囱发电系统效率的影响

【作者】 毛宏举； 李戬洪；

【Author】 MAO Hong-ju 1,2, LI Jian-hong 1

(1. Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China;

2. Graduate School of the Chinese Academy of Science, Beijing 100039, China)

【机构】 中国科学院广州能源研究所； 中国科学院广州能源研究所 广东广州510640 中国科学院研究生院； 北京100038； 广东广州510640；

【摘要】 采用计算流体动力学(CFD)方法对太阳能烟囱发电装置进行数值模拟,得到装置内部的温度场、速度场、压力场等分布情况。对集热棚的各种几何和物理参数进行研究和分析。结果表明,集热棚直径、太阳辐照强度、覆盖材料的透明度等诸多参数对系统效率有直接而重要的影响。 更多还原

【关键词】 太阳能烟囱； 计算流体动力学； 系统效率； 影响因素；

【Key words】 solar chimney； CFD； system efficiency； influence factor；

【文献出处】 可再生能源, Renewable Energy, 编辑部邮箱 , 2006年06期

xxxxxxxxxxxxxxxxxxxxx

2006

太阳能热气流电站系统的研究进展

【作者】 黄素逸；

【Author】 HUANG Su-yi (School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China)

【机构】 华中科技大学 能源与动力工程学院 湖北武汉 430074；

【摘要】 太阳能热气流电站系统是一种将太阳能转换为电能的装置,近年来对太阳能热气流电站系统的研究非常活跃。简要概括了关于太阳能热气流电站系统的国内外研究现状,总结了太阳能热气流发电系统的优势,介绍了其商用电站的建设进展,分析了在我国建设太阳能热气流电站的可行性。 更多还原

【关键词】 太阳能热气流电站； 集热棚； 透平； 烟囱； 蓄热层；

【Key words】 solar chimney power plant； collector； turbine； chimney； storage；

【基金】 教育部重点基金资助专案(104127)。

【文献出处】 东莞理工学院学报, Journal of Dongguan University of Technology, 编辑部邮箱 , 2006年04期

xxxxxxxxxxxxxxxxxxxxx

2006

太阳能热气流电站透平布置位置研究

【作者】 明廷臻； 刘伟； 高敏； 许国良； 潘垣；

【Author】 MING Ting-zhen 1, LIU Wei 1, GAO Min 2, XU Guo-liang 1, PAN Huan 1

(1. Huazhong University of Science and Technology, Wuhan 430074, China;

2. Tianjin Datang International Panshan Power Generation Company Limited, Tianjin 301900, China)

【机构】 华中科技大学； 天津大唐国际盘山发电有限责任公司； 华中科技大学 湖北武汉430074； 湖北武汉430074； 天津蓟县301900；

【摘要】 基于相对压力概念,建立了太阳能热气流电站系统的新数学模型,并通过数值模拟得到系统内的相对压力分布。根据系统相对压力的分布特点确定了透平布置的最佳位置:在烟囱的底部区域,相对压力最小,压力梯度最大,最适于布置透平;在技术容许的情况下,为实现能量转换效率最高,不宜采用能量梯级利用方案。 更多还原

【关键词】 太阳能热气流电站； 相对压力； 透平；

【Key words】 solar chimney power plant systems； relative static pressure； turbine；

【基金】 教育部重点基金资助项目(104127); 国家重点基础研究发展规划项目(G2000026303)

【文献出处】 可再生能源, Renewable Energy, 编辑部邮箱 , 2006年05期

xxxxxxxxxxxxxxxxxxxxx

2006

烟囱性状对太阳能烟囱发电系统效率的影响

【作者】 毛宏举； 李戬洪；

【Author】 MAO Hong-ju 1,2, LI Jian-hong 1

(1. Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China;

2. Graduate School of the Chinese Academy of Science, Beijing 100039, China)

【机构】 中国科学院广州能源研究所； 中国科学院广州能源研究所 广东广州510640； 中国科学院研究生院； 北京100038； 广东广州510640；

【摘要】 采用计算流体动力学(CFD)方法分析了烟囱对太阳能烟囱发电系统效率的影响。通过对烟囱高度、烟囱形状、烟囱内表面粗糙度和温度对系统的影响分析表明:在其它条件不变的情况下,烟囱高度和直径对系统效率影响最为显著,其次是形状,最后是烟囱内表面粗糙度和温度。 更多还原

【关键词】 太阳能烟囱； 计算流体动力学(CFD)； 系统效率； 影响因素；

【Key words】 solar chimney； CFD； system efficiency； influence factor；

【文献出处】 可再生能源, Renewable Energy, 编辑部邮箱 , 2006年05期

Xxxxxxxxxxxxxxxxxxxxx

2006

太阳能热气流电站系统研究

【Author】 MING Ting-Zhen LIU Wei XU Guo-Liang FAN Ai-Wu

(School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China)

【机构】 华中科技大学能源与动力工程学院； 华中科技大学能源与动力工程学院 武汉 430074； 武汉 430074；

【摘要】 由于现有模型不足以准确描述太阳能热气流发电系统的物理机制,本文提出一个更完善的数学模型去分析太阳能热气流电站系统的相对压力分布和系统抽力．模型中考虑了太阳辐射和系统尺寸参数对系统相对压力和系统抽力的影响。以西班牙试验电站为例进行数值模拟,探索系统尺寸参数和太阳辐射对系统相对压力和系统抽力的影响。数值计算结果与理论分析具有良好的一致性． 更多还原

【关键词】 太阳能热气流电站； 相对压力； 抽力； 数值模拟；

【Key words】 solar chimney power plant system； relative static pressure； driving force； numerical simulation；

【基金】 教育部重点基金资助项目(No．104127)

【文献出处】 工程热物理学报, Journal of Engineering Thermophysics, 编辑部邮箱 , 2006年03期