電漿重組產氫之電極設計與參數影響研究

Abstract

本文針對柴油燃料於小型電漿重組器的氫氣產出特性進行研究。研究方法以火花放電方式產生電弧，使碳氫燃料與含氧氣體混合物離子化之後，產生部分氧化及重組效應以產出富氫氣體。實驗參數為氧氣/柴油莫耳數比、重組器腔體流道形狀參數、輸入功率、電弧頻率等。 整個系統包括燃料氣體供應系統、參數控制系統、電漿系統、產物分析系統。其中電弧產生系統係由10KW直流電源供應器，其配合(5KHz~50KHz)頻率轉換器、升壓變壓器來完成高頻且高壓低電流輸出；反應器本體則是自行設計。產物分析系統，主要是利用氣相層析儀 (Gas Chromatography，GC) 來進行即時出口端氣體的即時定量分析工作。 由實驗結果得知重組器電漿及油氣分布重合度影響氫氣產出效率極大，利用流場數值模擬優化重組器構型，並透過調整O/C比來提高氫氣產出效率，在相同的燃料進料率下，適當的O/C 比會有較高的氫氣產出濃度。隨著燃料進料率的增加，氫氣的產出濃度會降低。電極表面之積碳會隨系統操作時間增長而增厚，進而使得轉化效率與氫氣產出濃度降低。此外，進料採用渦流方式，可提高氫氣產出濃度與莫耳流率。氣體於反應通道內駐留時間越長，氫氣產出濃度越高。本研究於最佳之參數設定下，氫氣產出濃度最高可達17 Vol%。

In this study, a small plasma diesel reformer was constructed to investigate the effects of design parameters on the performance of this apparatus. The methodology is to use a high voltage electric arc generator to ionize the hydrocarbon fuel and air mixture. The ionized gas is transformed into hydrogen-rich gas. The major parameters studied were O/C ratio, diesel flow rate, arc frequency, and reaction chamber diameter.

The system equipment included a fuel and air supply system, a plasma diesel reformer, an electric arc control system and a data acquisition system. One 10KW DC power supply with inverter and transformer was used to provide a high-voltage, low-current electric arc. The composition of the product gases from the reformer was measured by gas chromatography.

The results showed that higher production rate of hydrogen were obtained with a good plasma-fuel mixing. Numerical simulation for reaction chamber design and proper O/C ratio input were used to optimize hydrogen production rate. It also showed that carbon deposit grew on the electrodes with increased operation time. As the deposit grew, the hydrogen production and rate of fuel conversion decreased. As a solution, adopting mixture feeding swirl will improve hydrogen production and fuel conversion. As a whole, the best hydrogen concentration and production rate was 17Vol%.