Showing papers by "Annamalai Mani published in 2016"

Crystal growth, perfection, linear and nonlinear optical, photoconductivity, dielectric, thermal and laser damage threshold properties of 4-methylimidazolium picrate: an interesting organic crystal for photonic and optoelectronic devices

Abstract: The 4-methylimidazolium picrate has been synthesized and characterized successfully. Single and powder x-ray diffraction studies were conducted which confirmed the crystal structure, and the value of the strain was calculated. The crystal perfection was determined by a HRXR diffractometer. The transmission spectrum exhibited a better transmittance of the crystal in the entire visible region with a lower cut-off wavelength of 209 nm. The linear absorption value was calculated by the optical limiting method. A birefringence study was also carried out. Second and third order nonlinear optical properties of the crystal were found by second harmonic generation and the z-scan technique. The crystals were also characterized by dielectric measurement and a photoconductivity analyzer to determine the dielectric property and the optical conductivity of the crystal. The laser damage threshold activity of the grown crystal was studied by a Q-switched Nd:YAG laser beam. Thermal studies established that the compound did not undergo a phase transition and was stable up to 240 °C.

Experimental And Numerical Investigations of Ejector Jet Refrigeration System With Primary Stream Swirl

Abstract: Among the various heat powered refrigeration systems, vapour jet refrigeration system (VJRS) is attractive because of its simple and rugged nature. Ejector is a key component in VJRS and the performance of the whole system depends on the effective performance of the ejector, which in-turn could be improved by proper mixing of primary and secondary streams. This paper focuses on numerical and experimental studies of air ejector to analyse the influence of swirl on the performance of the system. Three-dimensional numerical analysis has been carried out for the ejector with and with no-swirl and the same has been verified with experimental studies using flow visualisation technique, particle image velocimetry (PIV). Swirl is generated in the primary stream by incorporating fixed vane swirler of camber angle of 10°, just upstream of the convergent portion of the primary nozzle which is a convergentdivergent (CD) nozzle. Velocity vectors obtained from PIV and CFD were compared and found that the results fall within an acceptable range. Studies have been carried out for an ejector under various primary stream pressures, with secondary and discharge pressure being open to atmosphere. By incorporating swirler of Type-2, in the primary nozzle, it has been observed that, swirl induced is low to have a significant improvement in entrainment ratio (around 2%) of ejector whereas swirler of Type-1 resulted in 5% improvement in performance compared to ejector with no-swirl.