Gradient particle size anode has shown great potential in improving the electrical performance of anode-supported solid oxide fuel cells (SOFCs). In the present study, a 3-D comprehensive model is established to study the effect of various gradient particle size distribution on the cell electrical performance for the anode microstructure optimization. The effect of homogeneous particle size on the cell performance is studied first. The maximum current density of homogeneous anode SOFC is obtained for the comparison with the electrical performance of gradient anode SOFC. Then the effect of various gradient particle size distribution on the cell molar fraction and polarization losses distribution is analyzed and discussed in detail. Increasing the particle diameter gradient can effectively reduce the anodic concentration overpotential. Decreasing the particle diameter of AFL2 is beneficial to reducing the activation and ohmic overpotentials. On these bases, the comprehensive electrical performances of SOFCs with gradient particle size anode and homogeneous anode are compared to highlight the optimal gradient particle diameter distribution. In the studied cases of the present work, the gradient particle diameter of 0.7 μm, 0.4 μm and 0.1 μm at ASL, AFL1 and AFL2 (Case 3) is the optimal particle size distribution.

Higher energy densities and the potential for nearly instantaneous recharging make microscale fuel cells very attractive as power sources for portable technology in comparison with standard battery technology. Heat management is very important to the microscale fuel cells because of the generation of waste heat. Waste heat generated in polymer electrolyte membrane fuel cells includes oxygen reduction reaction in the cathode catalyst, hydrogen oxidation reaction in the anode catalyst, and Ohmic heating in the membrane. A novel microscale fuel cell design is presented here that utilizes a half-membrane electrode assembly. An ANSYS Fluent model is presented to investigate the effects of operating conditions on the heat management of this microscale fuel cell. Five inlet fuel temperatures are 22°C, 40°C, 50°C, 60°C, and 70°C. Two fuel flow rate are 0.3 mL/min and 2 mL/min. The fuel cell is simulated under natural convection and forced convection. The simulations predict thermal profiles throughout this microscale fuel cell design. The exit temperature of fuel stream, oxygen stream and nitrogen stream are obtained to determine the rate of heat removal. Simulation results show that the fuel stream dominates heat removal at room temperature. As inlet fuel temperature increases, the majority of heat removal occurs via convection with the ambient air by the exposed current collector surfaces. The top and bottom current collector removes almost the same amount of heat. The model also shows that the heat transfer through the oxygen channel and nitrogen channel is minimal over the range of inlet fuel temperatures. Increasing fuel flow rate and ambient air flow both increase the heat removal by the exposed current collector surfaces. Ultimately, these simulations can be used to determine design points for best performance and durability in a single-channel microscale fuel cell.

3D amorphous carbon-based membrane materials with continuous carbon skeleton were obtained from the fruit waste pomelo peel. The microstructure shows honeycomb in the transverse direction with pore size ranging from 50∼100 μm, while in the longitudinal direction, the inner surface of the carbon membrane shows unique structure, i.e., rollable ladders with carbon rungs twinkled intimately around the vertical stringers, which is considered to contribute to the mechanical strength of the carbon membrane. The tensile test indicates that prolonged yield stage is observed in the stress-strain curve of the membrane material, the corresponding fracture morphology showing different fracture surfaces, which confirms the alleviation of the applied load by changing the crack direction. In addition, the elastic modulus of the carbon membrane material is 140 MPa. The elongation of the yield period is considered to facilitate the structure stability of the carbon membrane material as anode material in Lithium-ion battery (LIBs).

In this work, the reusable Lab-on-a-Chip or LOC was fabricated and developed to reduce its investment cost and to ease its operations. A sandwiched acrylic set was chosen to assemble the PDMS LOC which was aimed to investigate biological samples, especially the samples from animals. Chicken and sheep blood were chosen as the samples to implement two-phase flows with different red-blood-cell shapes. The chicken blood flow represented the viscous two-phase flow with the oval shape particles while the sheep blood flow represented the inadhesive samples with the round particles. The LOC electrodes from different materials as the sputtered nickel plate, the aluminium foil, the copper plate, and the gold foil were examined. Ratios between the anticoagulant solution and the biological samples were studied to find their effects on sample velocities and to find the best image to characterize the RBC flow behaviors. Since it was hard to characterize the particle flow in the inadhesive flows, the result pictures were analyzed and presented in terms of color intensities per unit area by using a computer program called “ImageJ”. The sheep-blood-flow results were validated with the hematology results which were the hematocrits to find their relationships between the hematocrits and the RBC flows. Among different LOC electrodes, the sputtered nickel electrodes were the most suitable electrodes in this current application. We found that the suitable anticoagulant-sample ratios for chicken and sheep samples were 5:1 and 1:1 by volume, respectively. The normal-health-condition sheep with the standard hematocrits higher than 28% showed the average-different-color intensities per unit area between cathode and anode at 39.485 pixels per unit area while the lower standard hematocrit samples, the hematocrits were lower than 28%, showed the average-different-color intensities at 14.641 pixels per unit area, the lower intensity the lower hematocrit. So the LOC coupled with “ImageJ” exhibited their capabilities to investigate the sheep blood conditions, especially, this coupled technique consumed less time than the traditional hematology process.

Based on CFD commercial software and the developed program which involved multi-component flow and diffusion, mass/heat transfer, electrochemical reaction and current field calculation, the performance of planar-electrode-support solid oxide fuel cell with different porosity anodes was investigated. The distributions of species concentration, temperature, electric potential, current and current density were obtained. The results show that this SOFC cell has good performance on species diffusion, current transfer and power output when anode porosity varies between 0.3 and 0.4. This work may be of significance to further research on the anode material.

Carbon dioxide bubble removal in anode diffusion layer is a critical technique in micro direct methanol fuel cells (μDMFCs) [1, 2]. By deriving a thermal lattice-Boltzmann model, we investigate the hydrophilic, thermal and geometric effects on the two-phase flow (CO 2 bubbles in methanol-water solution) in a microchannel of a μDMFC. The dimension of the example microchannel is similar to the diffusion layer. The length is 15.9 μm while the width (or height) is 1.5 μm, which are equivalent to the averaged pore size of the porous diffusion layer. A two-dimensional, nine-velocity (D2Q9) thermal lattice-Boltzmann model (TLBM) was derived in this paper.