Joining of the dissimilar materials is necessary and important from a manufacturing viewpoint. Therefore, the authors have developed a new laser direct joining method between metals and plastics. In this research, such joining was applied to join Si 3 N 4 ceramic and PET engineering plastic, although the metal was replaced by the ceramic. The shear strength of the joints was 3100 N, which was strong enough to elongate PET plates of 2 mm thickness and 30 mm width. It was confirmed that this laser joining process was effective to directly produce a strong dissimilar material joint of a ceramic and an engineering plastic.

The P-type perovskite oxides La 1-x Sr x CoO 3 are a promising group of complex oxide thermoelectric (TE) materials because of its a higher Seebeck coefficient. In this paper, the La 0.95 Sr 0.05 CoO 3 thin film was prepared by spin coating. A custom-made MEMS (micro-electromechanical system) based device was used to measure the voltage output and Seebeck coefficient of the thin film. The measured Seebeck coefficient of the thin film was 350 μV/K.

Thermal management of high power electronics is becoming a critical issue as the power density of semiconductors increasing. The flat heat pipe (FHP) is widely used in the electronic cooling because it is possible to interface with flat electronics packages without additional conductive and interface resistances. The heat flux of the next generation electronics may exceed 100 W/cm 2 , which is significantly beyond the cooling capabilities of commercially available FHP today. A novel micro scale hybrid wick was developed in this study to improve the effective thermal conductivity and working heat flux of FHP. The hybrid wick consists of multilayer of sintered copper woven meshes to promote the capillary pressure and microchannels underneath to reduce the flow resistance. The analysis indicates that the effective thermal conductivity and the capillary limit of flat heat pipe (FHPs) with this novel micro scale hybrid wicking structure can be significantly enhanced as compared to the reported FHPs. In this paper, the design of this innovative micro scale hybrid wick is illustrated. The fabrication and charging processes are also outlined. The preliminary experimental results show that the effective thermal conductivity can approach 12,270 W/(m·K), which is more than 30 times better than pure copper at approximate 91.3 W input heat.

This study concerns the geometric design of a cylindrical micropin-fin heat sink with multiple row configurations. The objective is to maximize the rate of heat transfer from the solid to the fluid subject to total fin volume and manufacturing constraints. A heat sink with dimensions of 1 mm × 0.6 mm × 1 mm is used for the computational analysis. An automated gradient-based optimization algorithm, which effectively handles an objective function obtained from a computational fluid dynamics simulation is implemented. The optimal design is obtained as results of balance of conductive heat transfer along the pin-fins with laminar forced convection. In the first case, the fins are arranged in two rows of pin-fins with different geometric sizes (diameter, height, and spacing between the fins). The optimal configurations obtained as a function of thermal conductivity ratio and Reynolds number are found to be in good agreement with those obtained from theory and numerical optimization. In the second case, the fins are arranged in rows of three, the effect of thermal conductivity and Reynolds number on the optimal configuration and the maximized heat transfer rate from the arrays of cylinders is reported.

Several polymeric thermal energy storage composites of high density polyethylene and polypropylene with two commercial paraffin waxes (PCM) P27 and P31 were prepared. The compounds were further reinforced with carbon fibers and carbon nanotubes to improve their thermal conductivity and heat transfer efficiency. The impact penetration behavior, service temperature and solvent resistance of the composites were improved by the addition of SEBS. DSC, optical microscopy, SEM, impact penetration and time–temperature history studies of the materials were done to determine the structure and thermal properties of these composites. The paraffins provide energy storage effect by solid–liquid phase change. The polymers encapsulate the paraffins so that the fluid motion of the PCMs is reduced during an application. The composites prepared were used for the construction of a small prototype swimming pool (laboratory scale). The time–temperature history of the composites, water in the container with and without energy storage materials and the environment was recorded. It was found that the composites significantly prolonged the cooling down time for water in the PCM pool. The difference between the cooling down temperature of water in a container with and without PCM composite was almost 4 hours. Moreover a computer program in C++ was written to solve the heat flow equations for the calculation of theoretical temperature–time curves.

Improved understanding of coal gasification chemical kinetics is needed to increase thermodynamic efficiency and to reduce undesirable CO 2 emissions. This work describes an optically-accessible entrained-flow coal gasifier designed and built to allow measurements of the major species at various stages of the chemical reactions. The 2-meter tall gasifier consists of five subsystems: the optical diagnostics, steam generator, coal feeder, external heaters, and gas sampling and analysis. A stoichiometric H 2 -O 2 flame generates superheated steam, the gasifying agent, which reacts with pulverized coal fed from a variable feed-rate pressurized powder feeder. To sustain the endothermic coal gasification reaction, radiant heaters provide 15 kW of external heating. Diagnostics to determine the major species concentrations consist of tunable diode laser absorption spectroscopy (TDLAS) measurements within the reactor vessel assembly and analysis of dry product gases using a gas chromatograph.

This paper reports the temperature and irradiance dependence of dye-sensitized solar cells (DSSCs) with acetonitrile-based electrolytes. The prototyped DSSCs had nanocrystalline titanium dioxide photoanodes and platinum thin film cathode. The photoanodes were sensitized with N-749 dye. The current-voltage characteristics of the DSSCs were measured at temperatures from 5 to 50 °C and under 500, 1000, and 1500 W m −2 irradiance. The open circuit voltage, V OC , decreased linearly with increasing temperature and had positive, logarithmic relation with irradiance. At temperatures lower than 15 °C, short circuit current density, J SC , was limited by the diffusion of I 3 − in the electrolyte and increased with increasing temperature. At higher temperatures the recombination of electrons injected into the TiO 2 conduction band was dominant over diffusion and J SC decreased with increasing temperature. Moreover, J SC increaed linearly with increasing irradiance. The DSSC photoconversion efficiency did not vary appreciably at temperatures lower than 15 °C but decreased with increasing temperature. Finally, the efficiency increased with increasing irradiance.