Study on Performance of Environmentally Benign and High Efficiency Plasma MHD Generator under Continuous Operation

发展环保、高效的电厂对减少二氧化碳排放、节约能源具有重要意义。本文以等离子体MHD发生器为研究对象，研究了圆盘MHD发生器的超音速闭环性能。闭环是MHD电厂的主要系统，惰性气体在闭环内循环。本实验以氩气为工质。实验结果总结如下：高温（> ~ 1900K）氩气循环时间为2.4 h。对氩气的热损益进行了研究，发现虽然回热器的能量效率较高，但在扩散器和排气管处的热损失较大。热损失大的原因是扩散器和排气管道的水冷却。同时提出了提高换热系数的方法。在换热系数增大4倍的假设下计算的氩气温度和热损失与实验结果吻合较好。讨论了回路内的压力比，结果表明，喷嘴喉道上游的总压力由总温度和质量流量决定。另一方面，下游的总压力由回路中的总质量和上游的总压力决定。进行了发电，观察到负载电阻与霍尔电压之间有很好的相关性。然而，输出功率仍然很小。

The development of environmentally benign and highly efficient power plant is important to reduce CO2 emission and to save energy resources. The present research was focused on a plasma MHD generator, and performances of the supersonic closed loop with the disk MHD generator were investigated. The closed loop is a major system in the MHD power plant, and noble gas circulates inside the closed loop. In the present experiment, argon was used as working fluid. Experimental results are summarized as follows.The high temperature (>1900K) argon circulation was carried out successfully during 2.4 hours. The heat gain and loss of argon was investigated, and a large heat loss was found at the diffuser and the exhausting duct although an energy efficiency of recuperator was high. The large heat loss was ascribed to water cooling at the diffuser and the exhausting duct. At the same time, the enhancement of heat transfer coefficient was suggested. The argon temperature and the heat loss calculated under an assumption of four times larger heat transfer coefficient have shown a good agreement with experimental ones. The pressure ratio inside the loop was discussed, and the result has indicated that the total pressure at the upstream of nozzle throat is decided by the total temperature and the mass flow. On the other hand, the total pressure at the downstream is determined by the total mass in the loop and the total pressure at the upstream. The power generation was carried out, and a good correlation between the load resistance and the Hall voltage was observed. However, the power output remained very small.