綠色推進-氧化亞氮/丙烷單基與雙基燃料推進器

Abstract

有鑑於環保意識的逐漸抬頭，使用無毒燃料的綠色推進是目前運載火箭及衛星推進器重要的發展方向之一，本實驗預計使用氧化亞氮(Nitrous Oxide, N2O，俗稱笑氣)作為單基推進器的燃料，同時可作為雙基推進器中的氧化劑，開發氧化亞氮單基燃料推進器與氧化亞氮/丙烷雙基燃料推進器。 氧化亞氮的觸媒催化分解放熱反應經過不同流量的測試，發現若是流量太低，溫度只集中於觸媒床前端；若是流量較高，往後帶的熱量會造成觸媒床溫度過高，但同時前端的溫度會開始下降，甚至低於反應溫度的門檻而停止反應，導致最後可能會連帶影響後端的溫度表現，因此在起始的反應僅能選擇一定範圍內的流量。在同流量的條件下，若觸媒腔體壓力比較大，溫度表現則比較低，表示壓力越高所能操作的流量越高。 由於溫度表現不均勻，導致無法達到好的反應表現，目前單基推進器在流量ṁ = 0.35 g/s的條件下，有比較好的Isp值62.4 s，而相對之推力值則為23.2 gf。在初步的雙基推進器測試中，推力值達到0.91 kgf，平均Isp值為100.7 s。

The development of space propulsion system using non-toxic propellant, “green propulsion”, is a new trend due to the fact that it is environmentally friendly. In this study, nitrous oxide (N2O) was not only used as a monopropellant but also served as the oxidizer burned with propane in a bi-propellant thruster. A catalyst bed composed of (Ruthenium, Ru) was used to facilitate the decomposition of N2O and the decomposition effectiveness was found to be affected by the flow rate of N2O. Our results showed that as the flow rate was low, most of the decomposition occurred in the front section of the catalyst bed. On the other hand, if the flow rate was too high, decomposition deteriorated quickly in the front section of the catalyst bed, and the temperature could rise quickly in the downstream of the catalyst bed, possibly beyond a critical value of 1200°C that the catalyst could afford. Therefore, an appropriate flow rate is a key to achieve the optimum decomposition of N2O and thus the maximum thrust. It was also observed that higher chamber pressure led to lower temperature performance, that is, the higher the chamber pressure is, the higher the flow rate can be operated and possibly the higher thrust could be achieved. In our studies, monopropellant thruster achieved a specific impulse of 62.4 s and a thrust of 23.2 gf with a flow rate of 0.35 g/s. For the bi-propellant thruster, a thrust of 0.91 kgf and a specific impulse of 100.7 were achieved.