We investigated the effect of electrolyte thickness and operating temperature on the heat and mass transfer characteristics of solid oxide fuel cells. We conducted extensive numerical simulations to analyze single cell performance of a planar solid oxide fuel cell (SOFC) with electrolyte thicknesses from 80 to 100 μm and operating temperatures between 700 °C and 800 °C. The commercial computational fluid dynamics (CFD) code was utilized to simulate the transport behavior and electrochemical reactions. As expected, the maximum power density increased with decreasing electrolyte thickness, and the difference became significant when the current density increased among different electrolyte thicknesses at a fixed temperature. Thinner electrolytes are beneficial for volumetric power density due to lower ohmic loss. Moreover, the SOFC performance enhanced with increasing operating temperature, which substantially changed the reaction rate along the channel direction. This study can be used to help design SOFC stacks to achieve enhanced heat and mass transfer during operation.

The present study conducts the numerical investigation of flow characteristics and thermal performance of spiral finned-tube heat exchangers. The effects of location of perforations (90°, 120°, and 150°) on heat transfer and pressure drop are analyzed for the air-side. The commercial computational fluid dynamics code ANSYS Fluent (V.17.0) is used for simulations with the RNG k-ε model based on the Reynolds-averaged Navier–Stokes equations. The velocity field, Colburn j-factor, and friction factor are analyzed to evaluate the heat transfer and pressure drop characteristics. Because of the flow through the perforations, the boundary layers on the fin surfaces are interrupted. This results in increased flow disturbances close to the fin, and the heat transfer performance increases compared to the reference case. The pressure drop, which is one of the disadvantages of spiral finned tubes comparing to plate or circular fins, decreases with perforations on the fin. Overall, the cases with perforated fin exhibit greater performance of area goodness factor considering the relationship between the heat transfer and the pressure drop.

This paper describes the fabrication and testing of a novel angle-scanning surface plasmon resonance imaging (SPRi) instrument. The combination of two stationary mirrors and two angle-controlled mirrors provides high accuracy (up to 10⁻³°) and high-speed angular probing. This instrument minimizes the angle-dependent image artifact that arises due to beam walk, which is the biggest challenge for the use of SPRi with angular modulation (AM). In the work described in this paper, two linear stages were employed to minimize the image artifact by adjusting the location of the angle-controlled mirrors and the camera. The SPRi instrument was used to visualize coalescence during dropwise condensation. The results show that the effect of the environment’s temperature on reflectance was less than 1% when the incident angle was carefully chosen for SPRi with intensity modulation (IM). This means that condensation visualization can be carried out at ambient temperatures, without the need for a Peltier stage or a thermally controlled condensing surface. The concept of pixel neighboring was employed to assess the probability of noise and the standard error of thin film measurement. Experimental analyses during dropwise condensation show (1) the presence of a thin film with thickness of one monolayer, and (2) surface coverage of 0.71 m²/m² by the thin film in the area between the droplets. In addition, analyses showed the existence of a dry area at the part of the substrate exposed by coalescence to ambient air. The results of this work undermine the validity of the film rupture theory as the dropwise condensation mechanism. Graphic