Optics and Photonics Society of Iran

Nano-fluids due to their high ability in heat transfer is widely used in the heat transfer systems. The use of nano-particles reduces the base fluid flow rate. Thermal lens spectroscopy is a powerful method in the study of nano-fluids. This method is used by one or two laser beams with different set ups. Meanwhile, in the use of two laser beams called as pump-probe technique, different arrangements of the beams can be applied. The pump beam creates a temperature gradient in the fluid and the probe beam is used for measuring the changes of the physical properties of the fluid. In this work, the thermal conductivity of a nano-fluid in presence of thermal lens producing by a pump beam using moiré deflectometry is presented. To minimize vertical convection, here the pump beam is impinging to the fluid vertically from the upper side. By measuring moiré fringes deflections around the location of the thermal lens and at places far from there, thermal conductivity of the fluid is determined