Enhancement of thermal conductivity and ultrasonic properties by incorporating CdS nanoparticles to PVA nanofluids

In the present work, semiconducting cadmium sulfide (CdS) nanoparticles have been synthesized by co-precipitation method. X-ray diffraction (XRD), UV–visible (UV/Vis) absorption spectroscopy, and high-resolution transmission electron microscopy (HRTEM) have been used for the characterization of the synthesized nanoparticles. Two-step technique has been used to formulate stable polyvinyl alcohol (PVA)-based CdS nanofluids at room temperature. Thermal conductivities of nanofluids at different temperatures have been measured using Hot Disc Thermal Constants Analyzer. Significant enhancement in thermal conductivity is noted at very low nanoparticle loading. Ultrasonic velocity and ultrasonic attenuation in the prepared nanofluids have been investigated using ultrasonic interferometer and Acoustic Particle Sizer (APS-100), respectively. APS-100 has been also used for the analysis of particle size distribution (PSD) of CdS nanoparticles in the prepared nanofluids. The PSD result of APS-100 is in good agreement with that of HRTEM. The characteristic behavior of CdS nanofluid is illustrated on the basis of its ultrasonic and thermal properties. The thermal conductivity enhancement increases with the temperature and reaches up to 61.6% for 1.0 wt% particle loadings at 80 °C. Our analysis shows that CdS nanofluids have potential application for effective heat transfer management in various cooling industries.