**4. Conclusions**

This study investigated the reformation of methane for hydrogen production by an energy conservative plasma fuel converter under different operation parameters and conditions. The experimental parameters include fuel flow rate, O2/C ratio, and S/C ratio. Additionally, the operating conditions are categorized into autothermal reforming reaction and energy conserving approaches. By conducting a series of experiments, the conclusions were drawn as followed:

For methane reforming, the reforming temperature for the best hydrogen selectivity is between 600 and 700 oC. By taking energy conservation approaches, the hydrogen production and the thermal efficiency of reformer are improved. Under the best parameter setting, the total thermal efficiency can be as high as 77.77 % with the methane flow rate of 10 NL/min and the O2/C ratio of 0.8. Furthermore, the hydrogen yield can be further increased to 86.26 % by adding an appropriate amount of water vapor (S/C ratio of 0.5), and the produced hydrogen flow rate is approximate 17.25 NL/min. And in the reforming process, the O2/C ratio, the fuel flow rate, the space velocity, and the reformate gas temperature have a great influence on reforming performance. As the first plasma reforming parameter (PRP1) increases, the H2+CO concentration shows a quadratic polynomial increase accordingly; and the thermal efficiency shows a logarithmic increase with the second plasma reforming parameters (PRP2). In this study, the HSC commercialized software was used for theoretical equilibrium calculation. The experimental results are very close to the value obtained through theoretical calculation. The regression coefficient (R2) can be as high as 0.918 between the experimented and calculated H2+CO concentrations.
