**2.1 Experimental equipment**

This study focuses on the energy conservative plasma fuel converters with waste heat recycling; a photo and a schematic diagram of the experimental equipment of the system are shown in Fig. 1 and Fig. 2, respectively. The reaction chamber was comprised of three subsystems: the fuel and gas supply system, the arc generation system, and the reformate gas sampling and analyzing system. The fuel and gas supply system was comprised a fuel nozzle and a flow meter. For the arc generation system, a car ignition system was used with a signal generator and an induction coil to generate arc. Converting car ignition system into a small high voltage DC power supply is practical, as it enabled the system to be directly equipped on-board, and the use of the existing equipment reduced the required space and cost of power supply. The anode of the sparking electrode was constructed by removing the earth electrode of spark plug, while the cathode was the reaction chamber itself. The specifications of the arc generating system are shown in Table 1 (a).

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The reformate gas sampling system of this experiment was designed to collect products from reforming reactions. A portion of the products was distributed to vehicle exhaust emission analyzer (Horiba MEXA-554JA) via pump to monitor the concentrations of the gas product. Another portion of the product was collected in the gas bags and directed into gas chromatography (Agilent 6850GC) for analysis. The reaction chamber was made of stainless steel, and could be further classified into the plasma reaction zone, the middle chamber, the catalyst section, the gas collecting chamber, and the fuel nozzle, as shown in Fig. 3. The internal surface of the reaction chamber was the ground electrode and the arc could be stretched freely with the intake flow. That is, the arcing system and the ground electrode were designed so as to enhance the uniform distribution of the discharge energy in the plasma reaction region. The main function of the catalyst section was to enhance the reforming reactions. The gas collection chamber was designed to thoroughly mix the

The commercialized catalysts were used for reforming, and the specifications of which are shown in Table 1 (b). This commercialized catalyst was chosen for its low cost, availability, small pressure drops, and great mechanical strength; in addition, the catalyst has a metal

The energy conservation measures of this study could be classified into waste heat recycling and heat insulation. For the heat recycling method, a stainless steel cover was added to form an air jacket on the catalyst outer wall, to direct the hot reformate gas back into the air jacket for heat recovery. For the heat insulation method, the outer surface of the reaction chamber was covered with glass fiber. The reaction temperature of the catalysts at the front, middle, and rear sections were measured via three K-type thermocouples. The average temperatures

Fig. 2. A schematic diagram of the experimental set-up

substrate, and therefore has an advantage of rapid cold-start.

reformate gas for sampling.


Table 1. The specifications for the plasma converter and the catalyst

Fig. 1. Photo of the experimental equipment

(a) Plasma power supply unit

Voltage (V) 12 4000 Current (A) 3.0 0.004 Power (W) 36 16 Arc frequency (Hz) 200 Variable

(b) Catalytic converter D × L (mm2) Φ46.2\*50.0 Pt/Rh ratio 5/1

Catalyst loading (g/ft3) 50 Cell density (Cell/in2) 100

Table 1. The specifications for the plasma converter and the catalyst

Fig. 1. Photo of the experimental equipment

Primary side Secondary side

Fig. 2. A schematic diagram of the experimental set-up

The reformate gas sampling system of this experiment was designed to collect products from reforming reactions. A portion of the products was distributed to vehicle exhaust emission analyzer (Horiba MEXA-554JA) via pump to monitor the concentrations of the gas product. Another portion of the product was collected in the gas bags and directed into gas chromatography (Agilent 6850GC) for analysis. The reaction chamber was made of stainless steel, and could be further classified into the plasma reaction zone, the middle chamber, the catalyst section, the gas collecting chamber, and the fuel nozzle, as shown in Fig. 3. The internal surface of the reaction chamber was the ground electrode and the arc could be stretched freely with the intake flow. That is, the arcing system and the ground electrode were designed so as to enhance the uniform distribution of the discharge energy in the plasma reaction region. The main function of the catalyst section was to enhance the reforming reactions. The gas collection chamber was designed to thoroughly mix the reformate gas for sampling.

The commercialized catalysts were used for reforming, and the specifications of which are shown in Table 1 (b). This commercialized catalyst was chosen for its low cost, availability, small pressure drops, and great mechanical strength; in addition, the catalyst has a metal substrate, and therefore has an advantage of rapid cold-start.

The energy conservation measures of this study could be classified into waste heat recycling and heat insulation. For the heat recycling method, a stainless steel cover was added to form an air jacket on the catalyst outer wall, to direct the hot reformate gas back into the air jacket for heat recovery. For the heat insulation method, the outer surface of the reaction chamber was covered with glass fiber. The reaction temperature of the catalysts at the front, middle, and rear sections were measured via three K-type thermocouples. The average temperatures

Waste Heat Recycling for Fuel Reforming 363

Fig. 5. The variation of the reformate gas yields produced by methane under various

energy, and was also advantageous in minimizing the size of the converter.

temperatures and lower O2/CH4 ratios gave better H2 and CO yields. However, the appeal of this system was its portability, and thus external energy supply was not an option. Therefore, heat released during the oxidation reforming process was used to provide the high temperature required for the reactions. This approach reduced the need for external

Fig. 4. A relationship chart of reforming mechanisms

O2/CH4 ratios at different reforming temperatures

Fig. 3. The configuration of the reactor

at the three points were used to define the actual temperature of the reformate gas. This temperature was also used to correspond with the theoretical calculation to verify the trend of the experimental results.
