HIGH EFFICIENCY MHD POWER GENERATION WITHOUT USING ALKALIMETAL

利用闭合循环磁流体动力（MHD）发电的概念可以实现高效发电。我们一直建议使用氙气作为种子材料，而不是碱金属，这会对环境产生不良影响，并降低系统的可靠性。到目前为止，由于发电机设计和运行条件的优化，虽然氦/氙工作气体可以提供与传统碱金属种子一样高的发电机性能，但为了实现高性能，保持等离子体在稳定的条件下是很重要的。其次，我们利用二维数值模拟的方法研究了等离子体稳定性与发电机性能的关系。氦/氙等离子体具有固有的不稳定性和不均匀性。这种不稳定性导致气体速度急剧下降和气体压力升高，从而导致发电机性能显著下降。然而，如果我们选择发电机的设计和运行条件，即使等离子体不稳定和不均匀，也不会产生这种不利影响，那么使用碱金属种子获得的稳定等离子体的性能就能成功地恢复到高值。该科研项目取得的上述成果已在国内外多个学术会议上发表。我们收到了令人鼓舞的讨论和评论，作为封闭循环MHD的新动向。建议继续进行氦/氙工质概念的实验论证。我们确实有一个计划来推进这个建议。

High efficiency electrical power generation can be possible by using the concept of closed cycle magnetohydrodynamic (MHD) electrical power generation. We have been proposing to use xenon as seed material Instead of alkali metal, which gives rise to bad environmental influence and to reduction of system reliability. So far, as a result of optimization of generator design and operating conditions) although helium/xenon working gas can provide significantly high generator performance as is obtained with conventional alkali metal seed, it is important to keep plasma in a stable condition in order to achieve high performance. Next, we have been studying the relation of plasma stability and generator performance by means of 2-dimansional numerical simulation. It has been clarified that helium/xenon plasma is inherently unstable and non-uniform. This instability produces strong decrease in gas velocity and increase in gas pressure, which result in significant degradation of generator performance. However, if we choose generator design and operating conditions so as to prevent from such unfavorable effects even if the plasma is unstable and non-uniform, performance successfully recovers to high value as obtained with stable plasma using alkali metal seed.Above results obtained by this scientific project have been presented many international and domestic conferences and symposiums. We receive encouraging discussions and comments as new movement in closed cycle MHD.We also are suggested to continue to perform experimental demonstration of the present concept of helium/xenon working medium. We do have a plan to move on along this suggestion.