EPRI: Collaborative Research: autoFlutter: Efficient, Waterless Power Plant Cooling

1357813 Glezer鉴于有限的水供应和成本，以及监管限制和环境问题，发电厂冷却系统中使用的水的消耗和提取速度已经变得难以维持。 然而，当前常规冷凝器系统的干空气冷却的有效性受到冷却空气的高热阻和差的空气热容量的阻碍。 显然，为了能够显著降低用于发电的水消耗，必须显著增强冷凝蒸汽与空气侧介质之间的传热。 早期改善空气侧传热的尝试集中在增加表面特征（凹坑等）上。在冷却鳍片上进行了一些改进，但效果有限，而且风扇功率显著增加。 该方案克服了空气侧热传输的限制，利用冷却空气流和微型之间的相互作用，颤振簧片（AFR）诱导冷凝器翅片表面附近的小尺度涡运动的形成和平流。 这种方法的一个独特之处在于，簧片颤振是通过利用来自嵌入式冷却气流的机械能以极低的压力损失损失产生的。 这些低成本的薄簧片可以针对冷凝器的不同区域进行定制，并且可以与冷凝器的外部表面一体地制造，或者作为现有冷凝器的改型组件的下降。簧片组件易于安装和维护，无需对工厂级基础设施进行改造。 初步的传热增强和压降分析以及冷凝器设计和发电厂模拟表明，与湿式冷却相比，使用AFR技术的风冷冷凝器可以提高工厂效率，同时显着降低水消耗。 该研究计划将专注于推动热电厂冷凝器技术的进步，以克服目前干燥空气冷却的限制，从而大大减少蒸发冷却的用水量。 本方法克服了空气侧热传输的限制，通过利用冷却空气流和微型，不稳定的颤振簧片（AFR）之间的相互作用，诱导冷凝器翅片附近的小尺度涡运动的形成和平流。 这种方法的一个独特之处在于，簧片颤振是通过利用来自嵌入式冷却气流的机械能以极低的压力损失损失产生的。 该计划包括综合实验/建模/数值研究，将重点放在实施，设计和优化AFR使用所需的基础知识，并证明其在改善电厂配置和操作条件下冷凝器翅片空气侧通道传热特性方面的功效。 格鲁吉亚理工学院的研究将集中在对AFR增强的传热特性的实验研究上，沿着AFR技术所能实现的新型冷凝器配置的建模、设计和测试。 约翰霍普金斯大学将专注于小规模传热和性能评估的CFD研究和优化AFR增强冷凝器配置。 最近在格鲁吉亚理工学院的空气冷却加热管道中证明了AFR的小尺度传热增强，具有显著的传热增强。 这些低成本的薄簧片可以针对冷凝器的不同区域进行定制，并且可以与冷凝器的外部表面一体地制造，或者作为现有冷凝器的改型组件的下降。簧片组件易于安装和维护，无需对工厂级基础设施进行改造。

1357813GlezerThe rate of consumption and withdrawal of water for use in power plant cooling systems has become untenable in light of limited water supply and cost, as well as regulatory restrictions, and environmental concerns. However, the effectiveness of dry air cooling of current, conventional condenser systems has been hindered by the high thermal resistance and poor air thermal capacity of the cooling air. It is clear that in order to enable an appreciable decrease in water consumption for power generation, the heat transfer between the condensing steam and the air-side medium must be significantly enhanced. Earlier attempts to improve the air-side heat transfer focused on the addition of surface features (dimples, etc.) on the cooling fins with limited success and significant increase in fan power. The proposed program overcomes the limits of air-side heat transport by exploiting interactions between the cooling air flow and miniature, autonomously-fluttering reeds (AFRs) to induce the formation and advection of small-scale vortical motions near the condenser fin surfaces. A unique aspect of this approach is that reed flutter is generated by harnessing mechanical energy from the embedding cooling air flow at exceedingly low penalty in pressure losses. These low-cost thin reeds can be tailored for different regions of the condenser and fabricated either integral to the external condenser surfaces or as drop in retrofit assemblies for existing condensers. The reed assemblies are easy to install and maintain without plant level infrastructure modifications. Preliminary heat transfer enhancement and pressure drop analyses coupled with condenser designs and power plant simulations have shown that air-cooled condensers using AFR technology can increase plant efficiency while significantly reducing water consumption compared to wet cooling. The research program will focus on enabling advances in thermoelectric power plant condenser technology to overcome current limits of cooling by dry air and thereby significantly reduce water usage for evaporative cooling. The present approach overcomes the limits of air-side heat transport by exploiting interactions between the cooling air flow and miniature, autonomously-fluttering reeds (AFRs) to induce the formation and advection of small-scale vortical motions near the condenser fins. A unique aspect of this approach is that reed flutter is generated by harnessing mechanical energy from the embedding cooling air flow at exceedingly low penalty in pressure losses. The program encompasses integrated experimental/modeling/numerical investigations that will focus on the fundamental knowledge needed to implement, design, and optimize the use of the AFRs, and demonstrate their efficacy in improving the heat transfer characteristics of finned air-side passages of condensers in power plant configurations and operating conditions. The research at Georgia Tech will focus on experimental investigations of the heat transfer characteristics enhanced by the AFRs along with the modeling, design, and testing of novel condenser configurations enabled by the AFR technology. Johns Hopkins University will focus on CFD investigations of small-scale heat transfer and performance evaluation and optimization of AFR-enhanced condenser configurations. Small-scale heat transfer enhancement by AFRs was recently demonstrated in air-cooled heated ducts at Georgia Tech with significant heat transfer enhancement. These low-cost thin reeds can be tailored for different regions of the condenser and fabricated either integral to the external condenser surfaces or as drop in retrofit assemblies for existing condensers. The reed assemblies are easy to install and maintain without plant level infrastructure modifications.