A comprehensive investigation of carbon-black-based nanofluids: Experimental, response surface methodology, and computational fluid dynamics approaches for heat transfer applications

In the current century, the rapid growth of the global population has significantly heightened the demand for energy and escalated waste production. This study aims to develop a technology that efficiently addresses both energy demand and waste management by creating nanofluids from production waste or byproducts, assessing their effectiveness through experimental measurements and simulations. A comprehensive investigation into the thermophysical properties and heat transfer performance of carbon-black-based nanofluids is presented. Carbon-black, a byproduct of petroleum combustion, is used to formulate nanofluids due to its superior thermal conductivity. The experimental analysis involves varying the weight concentrations (0.005 %, 0.01 %, 0.02 %, and 0.03 %), temperature (35°C to 55°C in 5°C increments), and particle sizes (30 nm, 80 nm, and 200 nm) to evaluate their effects on thermal conductivity, viscosity, specific heat, and density. A correlation model is developed to predict the temperature-dependent thermophysical properties, leveraging the Response Surface Methodology (RSM) and a 3^k factorial design with center points. This model facilitates the optimization of control factors, crucial for enhancing the nanofluid's heat transfer capabilities. Additionally, Computational Fluid Dynamics (CFD) simulations incorporate these correlations to provide dynamic, temperature-dependent analyses of the nanofluids, enhancing the realism and accuracy of the simulation outcomes. The research further explores the application of carbon-black nanofluids in a microchannel heat exchanger system, assessing the heat transfer performance through experimental and simulated approaches. Initial findings indicate that the carbon-black nanofluid enhances thermal conductivity by up to 0.9 % at minimal weight concentrations and temperatures, alongside a viscosity increase of 22.8 % at a 45°C and 0.01 % weight concentration. Optimizing the operational conditions to 45°C and 0.01 % weight concentration significantly improves the heat transfer rate while reducing pumping power requirements, yielding performance indexes showing improvements of 9.05 %, 7.80 %, and 8.3 % for the respective particle sizes compared to distilled water. The study confirms that carbon-black-based nanofluids not only enhance heat transfer efficiency but also promote sustainability by valorizing a petroleum byproduct, thus contributing to energy reuse and environmental conservation in industrial applications.