Effects of Gas Composition Just before Fuel Pulses on Power Generation Characteristics at Different Fuel Supply Frequency in Pulse Jet-Rechargeable Direct Carbon Fuel Cells

Abstract

Pulse Jet - Rechargeable Direct Carbon Fuel Cells (PJ-RDCFCs), in which small amounts of liquid hydrocarbon are supplied by pulse jet, were found to show different power generation characteristics depending on the time interval between fuel pulses (T int). For the T int range studied here (1 to 210 sec), both the maximum terminal voltage during a single cycle and the increase rate just after a fuel pulse can be controlled by T int, and this T int determines the fuel utilization and partial pressure of H2O and CO2. Thus, the gas composition just before a fuel pulse determines the degree of reforming reaction and chemical species contributing to the electrochemical reaction, which affects the power generation characteristics. Power generation at extremely short T int (1 sec) revealed that during pulse jetting, the terminal voltage was stable. Its average power density was 445 mW/cm2, which is high for electrolyte-supported SOFCs that use liquid hydrocarbon.

Novel Electrode Evaluation Method for Pulse Jet Solid Oxide Fuel Cells using Liquid Hydrocarbon Fuels

“…Previously, we estimated the relationship between U fuel and the reactions in each cycle from electrochemical measurements in the PJ-SOFCs. 40,41 When U fuel is set at a sufficiently small value, PJ-SOFC power generation involves the thermal decomposition of both isooctane and hydrocarbon (Eqs. 3 and 4), which have high partial pressures, and the direct electrochemical reaction of hydrocarbon fuel (Eq.…”

“…The relationship between U fuel and the reactions in the PJ-SOFC are described above. 40,41 In the present study, U fuel,end was fixed at 60%. Therefore, Eqs.…”

“…Against this background, we previously proposed a new SOFC that directly utilizes hydrocarbons. [40][41][42] In this cell, called a pulse jet SOFC (PJ-SOFC), a liquid-fuel injector used in gasoline engines is placed below the fuel electrode, which is directly supplied with liquid hydrocarbon fuel (see Fig. 1).…”

Poisoning Effect of Sulfur Compounds in Pulse Jet-Rechargeable Direct Carbon Fuel Cells

“…Isooctane was used as the fuel in this study because power generation characteristics have been reported for PJ-RDCFCs using isooctane as the gasoline model as fuel (15,16).…”

“…Gas composition in the anode changes because thermochemical reactions and electrochemical reactions occur between pulses, and thus the chemical species that contribute significantly to the electrochemical reactions in PJ-RDCFCs react selectively. Consequently, the type of chemical species that react can be selected by controlling the fuel supply frequency (16). Though the amount of deposited carbon on the anode increases due to sulfur, there is a possibility that carbon deposition can be controlled by adjusting the operating conditions in which carbon is more contributive to the electrochemical reactions.…”