Fundamental studies on combustion and microfluidics

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1. AMMONIA AS AN ALTERNATIVE FUEL FOR GAS TURBINES     ------------------ Ammonia is readily available worldwide, and is easily liquefied at modest pressures for storage and transportation. It has a calorific value similar to methanol, but pure ammonia has poor combustion characteristics. However, it can be partially decomposed at relatively low temperatures to self-generate some hydrogen, thus eliminating this problem. The absence of carbon in the combustion of ammonia is a major step towards eliminating greenhouse gases, but nitrogen oxides (NOx) remain a critical concern. The proposed experimental facility will consist of a catalytic ammonia decomposition chamber and a combustion tube with multiple rows of holes for secondary air injection. Partially decomposed ammonia and preheated primary air will be introduced into the combustion chamber through co-axial tubes with counter-swirl, and temperatures and NOx levels will be monitored at various locations along the combustion chamber. The ultimate goal is to develop staged-combustion strategies for ultra-clean ammonia fuelled gas turbine burners. ------------------     2. MICRO-SCALE FLOWS AND HEAT TRANSFER IN CHANNELS     ------------------ Micro-scale duct flows behave very differently from their macro-scale counterparts. For gases, rarefaction causes velocity-slip and temperature-jump at the walls, resulting in lower friction and heat transfer coefficients. Furthermore, effects due to gas compressibility and viscous dissipation become important. Liquids are largely immune to compressibility and rarefaction, but may experience electro-kinetic and electro-osmotic effects due to the presence of an electrically charged region near the walls. In an electro-kinetic device, the excess charge within this region is moved with the fluid to create an electric current by the application of a pressure difference across the channel. In an electro-osmotic device, the excess charge is moved by the application of an external electric field, thereby creating a liquid pump. In the proposed research, the behavior of gas and liquid flows in rectangular and trapezoidal micro-channels will be investigated using numerical methods.