The modeling in this study was conducted to maximize the high performance of adhesive materials. Aluminum nitride (AlN) and epoxy resin were used to model AlN in the form of a sphere and resin in a liquid state. The results are expected to be dependent on the location of the sphere in the resin. First of all, spherical AlN is regularly stacked in the basic form of 3x3. Secondly, the volume ratio of AlN was maximized at a unit volume considered of the packing factor of AlN. Air pockets with the same diameter of AIN can be substantially added inside the resin. Then, the heat transfer coefficient of the air was very low, so it was considered as a factor that could sufficiently affect the heat transfer coefficient of the adhesive material. The modeling was compared the cases with and without the air pockets. Thirdly, the modeling of the same structures showed the larger heat transfer rate when the material was changed to zinc oxide (ZnO), which has the larger heat transfer coefficient than AlN. Finally, the molecular crystal of ZnO can be implemented as a tetrapod type. The ZnO of tetrapod type had the good heat transfer rate because of the greater proportion per unit volume than the sphere.
In order to meet the environmental regulation due to global warming issues, the new energy resource such as ocean temperature between surface and deep see level or wasted heat resources from power plant have received much attentions as a renewable energy, which is not used in conventional power cycle using a water-steam phase change. Instead, organic Rankine cycle (ORC) based on a properly selected refrigerant can be used for power generation by utilizing the relatively hot source from cooling water from conventional power plants, internal combustion engines and industrial processes. To operate ORC cycle in low temperature difference, a proper selection of working fluid is very essential to design the ORC system for industrial application. However, the selection of working fluid is currently very limited due to ozone depletion by CFC as well as global warming issues by CO2 emission. Under new regulations, we should design and select appropriate refrigerants which can meet the environmental regulation for lower global warming potential (GWP) and lower ozone depletion potential (ODP). In this study, the convective heat transfer coefficients of single, binary or ternary refrigerants were studied through a pool boiling test. Also, the selected refrigerants were tested by lab scaled ORC system.