Thermal efficiency of green-synthesized SiO2 nanoparticle-doped coolants applied in internal combustion engines

Abstract

The present study investigates the theoretical and experimental potential of SiO2 nanoparticles to enhance heat transfer in cooling water systems. In contrast to the conventional methods outlined in the extant literature, the SiO2 nanoparticles were synthesized using a green approach, employing rice husks as the starting material. The resulting SiO2 nanoparticles exhibited an average diameter of 20-35 nm. The study then proceeded to evaluate the effects of varying concentrations of SiO2 (0.2%, 0.4% and 0.55%) on heat transfer in engine cooling water under two distinct engine loads (7 kW and 8.5 kW). The highest heat transfer enhancement was recorded at 64.3% for the 7 kW engine load and 67.5% for the 8.5 kW engine load, with an additive of 0.55% SiO2. A study was conducted to ascertain the stability of cooling water to which nanoparticles had been added. The results indicated that a homogeneous and non-settling mixture was obtained for a considerable duration. A preliminary economic evaluation was conducted to ascertain the feasibility of synthesizing SiO2 using green methods. The study found that simple payback times were calculated below one year for all the SiO2 ratios. The performance effects of the additive, which is naturally produced, economically and environmentally friendly, were evaluated technically and economically.