ELISA ENGLISH's Blog 英語園地

*Translated by Elisa on 5/19/08 - 版權所有*

太陽能煙囪是一種熱驅動式發電系統，利用可透光的外罩吸收太陽熱幅射加熱空氣，熱空氣受浮力作用與煙囪效應而加速上升，再藉由煙囪底部的風力渦輪產生電力，

Solar chimney is a thermal power generation system.  Hot air for the solar chimney is produced by absorbing solar irradiance through a translucent collector, and accelerates upwards by the buoyancy force and the stack effect, generating electricity through a wind turbine in the base of the chimney.     

目前現有的大型太陽能煙囪發電系統，在煙囪高度為1公里的尺度下，最高效率約只有百分之一，因此需要相當廣大的集熱面來達到所需求的發電量，但由於系統架構簡單與運作成本低廉，每單位千瓦發電成本仍低於其它太陽能發電系統。

Currently, the existing large-scale solar chimney power plants only have an energy conversion efficiency of 1% at their highest at the scale of 1km chimney height, and require an enormous absorber plate to generate the capacity required to meet the energy demand.  However, due to the simple system structure and cheap operating cost, its electricity generation cost per kilowatt hour is still lower than that of other solar power generation systems.   

本文目的在探討太陽能煙囪幾何外型對發電效率之影響，包含管內流道們的變化、外罩間隙與半徑比例等相關參數，雖然高度差是造成煙囪效應的主要因素，但煙囪高度直接影響到發電成本，因此在有限的高度內提升發電效率，即增加流體熱能對動能的轉換效率，是本研究的重點。

The purpose of this study is to discuss the impact of solar chimney geometric shapes to energy conversion efficiency.  This includes relevant parameters such as changes of flow areas with changes of chimney heights, sealants of the collectors and proportions of radius.  Although the difference in height is the major cause of chimney (stack) effect, the height of chimney directly impacts the cost of power generation. Thus, enhancing power generation efficiency within a limited height will increase the conversion efficiency to kinetic energy of the fluid.  This is the focal point of this research.

透過一種漸擴式的管型，可改變煙囪管內的壓力分佈，在喉部產生更快的流速，隨著流量的提升，使出口流體平均溫度下降，而得到更大的質流率，有利風力渦輪的運作，透過縮小尺度實驗模型驗證的結果，使用漸擴管在轉換效率上為直管的4~5倍，並且模擬在100m煙囪高度的尺度下，即可達到1%以上的效率。

Through a divergent nozzle, we can change the distribution of pressure inside a chimney, generate a faster fluid speed at the nozzle throat, lower the average temperature of the fluid at the outlet and obtain the highest flow rate along with the increase of mass flow.  This will help the operation of wind turbine.  The reduced-scale model experiment proves that the (energy) conversion efficiency of a divergent nozzle is four to five times that of a vertical pipe and will reach above 1% efficiency under the simulation of a scale of 100m chimney height. 

** Partial document posted.  The rest of the document is password protected to protect the person who asked me to translate her thesis**