Abstract
The present work aims to study the effect of nano-particles volume fraction of nano-fluid on the heat transfer during pool boiling with different values of heat flux. The concentration ratios by volume in demineralized water are taken as 0.02 %, 0.20 %, 0.40 %, 0.60, and 0.80 % for Al2O3 nano-particles and 0.02 %, 0.06 %, and 0.20 % for CuO nano-particles. Heat transfer coefficients for pool boiling were established experimentally for different values of volume fraction and heat flux. The heating element is made from an aluminum alloy (AL 6061) with a circular smooth surface of 100 mm diameter and 10 mm thickness. The nano-particles porous layer that builds up during boiling is observed by a scanning electron microscope of the heated surface before and after the boiling. The results demonstrate that the heat transfer rate depends on the concentration ratios and heat flux. Using nano-particles decreases the pool boiling heat transfer in comparison with demineralized water. Due to the deposition of nano-particles on the heated surface, lower heat transfer is obtained for a lower bubble departure compared with demineralized water for the small wall superheat.
Highlights
Ahmad et al [1] investigated the surface characteristic effect and electrostatic field on the rate of heat transfer and their critical heat flux for pool boiling of R-123 at 1 bar with saturation condition
Nazari and Saedodin [12] studied experimentally the nano-fluid pool boiling on the aluminium surface at different volume fractions which are 0.002, 0.01, 0.05 and 0.1 vol.%, the results showed that by adding the nano-particles, the critical heat flux increase at a certain concentrations
After pool boiling in Al2O3 nanofluid, a qualitative observation of the heated surface was noticed where the heating surface was prepared for SEM
Summary
Ahmad et al [1] investigated the surface characteristic effect and electrostatic field on the rate of heat transfer and their critical heat flux for pool boiling of R-123 at 1 bar with saturation condition. Ribatski and Thome [4] presented an experimental analysis of heat transfer through pool boiling of R134a on different tubes for a wide range of high heat flux from 20 to 70 kW/m2 and three different saturation temperatures of 5, 10, and 20 °C. Their results showed that the effect of saturation temperature has no significant effect on the heat transfer coefficient except for Turbo-CSL while for increasing the heat flux, a slight noticeable decrease in heat transfer coefficient or an almost constant value are observed. An overview has been presented by Kavitha et al [5] for some developments in nano-fluids such as the preparation methods, the evaluation methods for their
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