Nano-technology has become recognized as one of the essential technologies in the 21st century. The nanofluids terminology, which describes fluid combined nanoparticles, was introduced by Choi of the Argonne National Laboratory in the U.S. Department of Energy. The carbon particles with metal lattice or graphite structures generally exhibit thermal conductivities those are hundreds of times greater than pure fluids. Especially due to their outstanding electric and thermal conductivities, carbon nanotubes have become an important entity in the scientific field.
Therefore, in this study, for increasing the efficiency of solar collector and heat exchanger, the thermal conductivity and viscosity of nanofluids were measured. Nanofluids were manufactured by ultra-sonic dispersing Oxidized Multi-walled Carbon Nanotubes in base fluids at the rates of 0.0005 ∼ 0.1 vol%. We used distilled water, ethanol and mixed water-ethanol as base fluids. The thermal conductivity and viscosity of nanofluids were measured at the low temperature(10℃), the room temperature(25℃) and the high temperature(70℃).

2. Characteristics of Thermoacoustic Laser

Thermoacoustics is a field that involves the study of both acoustics and thermodynamics. In other words it os known as the study that involves sound waves and the conversion of one form of energy into another. When a sound wave travels through a gas, it creates pressure and velocity oscillations within the gas it travels. These oscillations will produce a "thermoacoustic" effect. The engines which produce a "Thermoacoustic" effects are known as thermoacoustic enginge. Thermoacoustic engines find their use in various fields like medicine, thermodynamics, fluid mechanics and material sciences and so on. For example, ultrasound is used to shatter kidney stone. Shock waves are used in mining and material processing. They are also used in cleaning and sterilizing surfaces and medical instruments by sanitizing liquids. Recent developments in thermoacoustic engines like using solar energy or waste heat to run them makes it promising and economically sound for generating large quantities of acoustic energy. These engines have been looked at with increased interest in recent years due to useful applications like converting thermal energy into acoustic energy thermoacoustic energy and acoustic energy on to refrigeration.
In this study, to find out the characteristics of thermoacoustic laser, we experimented thermoacoustic laser oscillated at various shapes of resonance tube, stack, power.