Preparation, stabilization, and thermal characterization of CuO/water nanofluids applicable to domestic solar water heater

Abstract

In this contribution, an experimental investigation has been carried out to analyze the stability and light absorbance characteristics of CuO/water nanofluids applicable to domestic solar water heaters. Nanofluids are prepared at 0.01–0.05 wt% by dispersing dry CuO nanopowder in water in presence of Gum Acacia (GA) stabilizer via ultrasonic agitation. The stability of the nanofluids is examined through gravity sedimentation. The samples are exposed to natural sunlight as well as LED light to examine their light absorbance potential by virtue of temperature rise. The light absorbance potential of nanofluids as compared to water is expressed as Temperature Variation Ratio (TVR). The nanofluids remain stable for six months. The sedimentation is more in higher concentration relative to their dilute counterparts. The absorbance capacities of the nanofluids augment with the nanoparticle addition to base fluid. However, 0.01 and 0.05 wt% samples show relatively lower absorbance due to a higher sedimentation rate. Maximum absorbance is observed with 0.03 wt% which shows a maximum temperature rise up to 60 °C under sunlight and 56 °C under LED light. Whereas, water shows a maximum increase up to 52 °C under sunlight and 48 °C under LED. The TVR shows the highest values of 2.3 and 1.86 with 0.03 wt% sample when kept under sunlight and LED lights respectively. Hence, nanofluids are recommended as working fluids in solar water heating applications.