Abstract
Natural ester oils are the current target of many industries and electrical utilities as electrically insulating fluids to replace the conventional mineral oils. However, as previously investigated, most natural ester oils are based on edible products, causing a negative impact on the food crisis. Accordingly, nonedible green nanofluids based on cottonseed oil have been targeted in the present study. Additive graphene nanoparticles (0.0015 wt%, 0.003 wt%, 0.006 wt%, and 0.01 wt%) along with surfactant sodium dodecylbenzene sulfonate (SDBS) were used (1:1) due to their promising impact on dielectric and thermal properties. Experimental methods introduced were including characterization of graphene and preparation of dielectric nanofluids (DNFs). The main concern for any nanofluid to be usable in transformer applications is its long-term stability. The effect of various ultrasonication periods (10, 20, 30 and 60-minute) on short-term stability of nanofluids was preliminary investigated by visual inspection, highest short-term stability was obtained at 30-min and 60-min. Considering short-term stability results, the two most stable samples were investigated and compared for long-term stability through ultraviolet-visible (UV-Vis) spectroscopy to find the suitable ultrasonication time. In addition, dielectric and thermal properties of these samples were investigated and compared. Physical mechanisms were discussed for the obtained enhancements considering the effect of ultrasonication period on the number of dispersed nanoparticle sheets per unit volume and the corresponding effect on dielectric and thermal properties.
Highlights
Dielectric nanofluids (DNFs) have gained a great interest for the application with power transformers
Natural ester oils have the advantages of better biodegradability and higher flash and fire points compared to mineral oils
This study aims to develop cottonseed oil (CSO) based DNFs with long-term stability using a combination of graphene and sodium dodecylbenzene sulfonate (SDBS) with optimized ultrasonication period
Summary
Dielectric nanofluids (DNFs) have gained a great interest for the application with power transformers. These types of fluids are based on mineral oils. Ester oils can be natural ester oils or synthetic ones. Natural ester oils have the advantages of better biodegradability and higher flash and fire points compared to mineral oils. Natural ester oils proved to decrease the transformer aging and its loss of life [5], [6]. The only drawback of natural ester oils is their high viscosity which negatively impacts the oil flow within the transformer and the subsequent heat transfer to the surrounding
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have