Abstract : Nanofluids are dilute suspensions of nano-sized particles in liquids. They have attracted great interest as heat transfer fluids in recent years due to their greatly enhanced thermal characteristics. However, so far most of the early works have focused mainly on the study of their thermal conductivity. Experimental data for convection heat transfer (especially, boiling heat transfer) are very limited and controversial. In this project, systematic experiments will be carried out to formulate stable aqueous based nanofluids (TiO2-based, etc.), and to investigate their heat transfer behaviour under nucleate pool boiling conditions.

Abstract : Vacuum freeze drying is the most widely used freeze drying process for pharmaceutical, biological products, etc. The main disadvantages of this technique are the high fixed and operating costs. To overcome these limitations atmospheric pressure freeze-drying concept is postulated as an attractive alternative. A novel atmospheric freeze drying system has been developed using a vibrated bed dryer coupled with multimode heat input. Preliminary experiments have been conducted to test the setup using selected adsorbent particles mixed with previously frozen products. The aim of this experimental project is to examine and correlate the effects of vibration and equipment parameters on drying kinetics as well as quality of various heat-sensitive products. Therefore, a systematic parametric evaluation over a broad range of possible parameter values will be carried out along with simple mathematical models of the process.

Abstract : New generation pulse combustors which overcome some of the key shortcomings of the conventional cylindrical combustor such as large dimensions, low gas pressure developed, noise etc. The ignition process of a methane-air mixture in novel geometry pulse combustors will be simulated using a computational fluid dynamic model of pulse combustion. The pressure-heat release relation will be analyzed based on numerical results. A parametric study will then carried out to improve the combustion performance, including study of different fuels including hydrogen. This project will contribute to better designs of pulse combustors.

Abstract: Fuel cells are electrochemical devices that convert chemical energy of a type of fuel (typically hydrogen) into electricity and generate the by-product of heat and water. For all the various types of fuel cells, Proton Exchange Membrane (PEM) Fuel Cells has emerged as viable candidates for future power generating devices in the automotive, distributed power generation and portable electronic applications. It is essential to understand the key parameter effects on fuel cell operation in order to improve the performance.

In this study, systematic experiments will be conducted on both single and stacked PEM Fuel Cells to provide fundamental parametric experimental data and subsequently optimize their operating conditions. The student will continue to enhance the current fuel cell performance available in ME, NUS by studying the effects of pressure and humidification of the gas streams using the available electrolyzer and flow control devices, as well as fabricating new gas channel designs to investigate the effects of flow channel design on cell performance. A series of polarization curves with different will be obtaineded. The experimental data will be compared with computational results obtained elsewhere for further analysis and verification.