华南理工大学科研成果入选2012年度中国科学十大进展(中英文)

Experimental Investigation and Numerical Simulation of Natural
Convection Heat Transfer in Converging-Diverging Tube with Twisted Tapes


Abstract:
The natural convection heat transfer of water in a vertical converging—diverging tube(CD)with regularly spaced twisted tapes was experimentally investigated and numerically simulated,and the natural convection heat
transfer coefi cient varying with the twisted tape number was explored.Then,the results were compared with those
of smooth tubes,and the distributions of velocity and temperature,as well as the variations of heat transfer coeficient and heat flux with axial distance,were simulated with Fluent.It is found that the heat transfer coeficient remarkably increases with the number of twisted tapes and keeps unchanged when 7 twisted tapes are inserted,and that the heat transfer enhancement is independent of the type of twisted tapes.Simulated results indicate that the flow resistance increases with the number of twisted tapes and that the optimal number of regularly—spaced twisted tapes is 7.The authors also primarily analyze the mechanism of the natural convection heat transfer enhancement interrelated by the CD and the regularly—spaced twisted tapes,discuss the change of average tangential velocity with the axial distance and point out that the enhancement of heat transfer is due to the increase of tangential wall velocity.
Key words:natural convection;twisted tape;heat transfer enhancement;numerical simulation


2013年3月9日,科技部基础研究管理中心发布2012年度“中国科学十大进展”,华南理工大学国家杰出青年基金获得者吴宏滨教授和中国科学院曹镛院士研究组一项科研成果人选。该项成果利用一种倒置结构实现了能量转换效率达到9.2%的聚合物太阳电池,刷新了同行评审的科学文献报道中单结聚合物异质结太阳电池能量转换效率的世界最好水平。这一效率得到国家光伏质检中心的独立认证。该研究成果还在国际著名学术杂志<Nature Photonics}(《自然光子学》)上发表,并被该期杂志选为研究亮点。
聚合物太阳电池是指核心组成为共轭聚合物(高分子)半导体材料的一种新型的太阳电池,是一种有潜力的低成本可再生能源技术,在太阳能发电、野外便携式充电器、太阳能电动交通工具、发电式建筑外墙等方面具有广阔的应用前景。中国科学院院士、中国科学院上海技术物理研究所研究员褚君浩认为,聚合物太阳电池与无机半导体太阳电池有非常强的互补性。华南理工大学的研究表明,小面积聚合物太阳电池的实验室效率已经十分接近非晶硅太阳电池的水平,通过进一步进行大面积电池均匀性研究和提高能量转换效率以及加强长期室外稳定性的研究,有可能具有规模化生产和应用的前景,是一类值得大力发展的薄膜太阳电池。
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