Investigate a hybrid open-Rankine cycle small-scale axial nitrogen expander by a camber line control point parameterization optimization technique
Investigate a hybrid open-Rankine cycle small-scale axial nitrogen expander by a camber line control point parameterization optimization technique
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DOI：
10.1016/j.applthermaleng.2017.08.083
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发表时间：
2017-12
影响因子：
6.4
通讯作者：
Khalil M. Khalil-Khalil-M.-Khalil-30807062;S. Mahmoud;R. AL-Dadah;A. B. Ennil
中科院分区：
文献类型：
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作者：
Khalil M. Khalil-Khalil-M.-Khalil-30807062;S. Mahmoud;R. AL-Dadah;A. B. Ennil
在过去的几十年里，太阳能和风能等低品位热源提高了先进可再生技术的效率，如联合朗肯循环，显著减少了二氧化碳排放。为了解决这种可再生能源的间歇性问题，已经使用了储能技术来平衡电力需求和平稳能源生产。本文利用工程方程解算器(EES)软件对混合开式朗肯循环进行了详细的热力学分析，以考察液氮储能系统的循环性能。在这种循环结构中，传统的闭环朗肯循环(顶循环)与直接开式朗肯循环(筑底循环)相结合，形成了一个更有效的系统，可以解决可再生能源不连续的问题。在直接开朗肯循环中，小型膨胀机是提高循环性能的主要部件，因此，需要对该小型膨胀机进行优化，以实现最高效率，以实现高系统性能水平。在这项工作中，利用一维初步设计和CFD三维Ansys设计探索以及一种新的弯曲线控制点参数化技术，对一台小型氮气轴流膨胀机进行了优化和建模，并将其纳入开式朗肯混合循环。实践证明，该优化设计方法可以将汽轮机效率从72%提高到76.3%，输出功率从2076 W提高到2597.6 W。采用控制点方法的优化方法还可以使循环热效率比基线设计提高3.38%。这些结果表明，对于小流量、低转速的小型膨胀机，采用叶片弯曲线控制点的参数化技术进行全模拟优化是有潜力的。
During the last few decades, low-grade heat sources such as solar energy and wind energy have enhanced the efficiency of advanced renewable technologies such as the combined Rankine cycle, with a significant reduction in CO2emissions. To address the problem of the intermittent nature of such renewable sources, energy storage technologies have been used to balance the power demand and smooth out energy production. In this study, a detailed thermodynamic analysis of a hybrid open Rankine cycle was conducted by using engineering equation solver (EES) software in order to investigate the performance of such a cycle using a liquid nitrogen energy storage system. In this cycle configuration, the conventional closed loop Rankine cycle (topping cycle) is combined with a direct open Rankine cycle (bottoming cycle) for a more efficient system which can solve the problem of discontinuous renewable sources. In the direct open-Rankine cycle, the small expander is the main component that can improve the cycle’s performance and as a result, this small expander needs to be optimized for maximum efficiency to achieve high system performance levels. In this work a small-scale nitrogen axial expander has been optimized and modeled to be incorporated into a hybrid open-Rankine cycle, using a one-dimensional preliminary design and CFD three-dimensional ANSYS design exploration and a novel camber line control point parametrization technique, which is outlined in detail. The design optimization approach has been proven as an effective tool that could enhance turbine efficiency from 72% to 76.3% and output power from 2076 W to 2597.6 W. The optimized turbine using the control points’ approach could also improve the cycle’s thermal efficiency by 3.38% compared with the baseline design. Such results underline the potential of full simulation optimization by using a blade camber line control point’s parametrization technique for a small-scale expander with low flow rate and rotational speed.