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- MakaleAçık Erişim2025Scopus SJRQ2Investigation of the effect of the metallographic properties of vertical and horizontal cylinders made of ferrochrome with different contents on heat transfer by natural convection
Kahraman, Gökhan; Taşgın, Yahya
In this study, ferrochrome materials containing elements with different content ratios were manufactured into six-cylinder specimens, 13 mm in diameter and 16 mm in length, and heated in a furnace up to 500 °C. The heated cylinders were removed and left to cool in vertical and horizontal positions in a 16 °C environment. The temperatures were recorded using thermal cameras at certain intervals while the materials cooled down. The six specimens, whose metallographic differences were identified using SEM and XRD analysis devices, were placed vertically and horizontally, and their heat transfer by natural conviction was noted. In the calculations, each specimen’s Nusselt and Rayleigh numbers were identified based on time and then compared. The fastest cooling among the specimens occurred in the ferrochromium material with 55.93% Cr, 31.11% Fe, 11.56% C, 0.48% Si, 0.83% O, and 0.09% Al compound ratios, both in vertical and horizontal positions. Additionally, since the Nusselt number of the horizontal cylinders remained below one based on their position, their natural convection flows were not initiated. The cooling in the horizontal cylinders occurred via conduction.
- MakaleYalnız künye2024Scopus SJRQ2Evaluating the metallographic properties and performance of heat transfer by natural convection of graphene-coated glass used for heating
Kahraman, Gökhan; Taşgın, Yahya
In this study, a decorative electric heater was manufactured to reduce carbon emissions related to residential and office heating, and this heater was metallographically evaluated. In addition, the heating performance of the manufactured plate was investigated by examining its heat transfer capacity by natural convection. For this purpose, the surface of the tempered glass plate was coated with graphene by spraying to improve its electrical and heat conduction properties. Copper strips were attached to both sides of the plate to allow for an electric current. The plate was connected to mains electricity, and its change in surface temperature over time was measured. Using the measured temperature values, the heat transfer rate by natural convection on the plate surface was calculated. As a result of the calculations, it was determined that the graphene-coated tempered glass plate reached a heating performance of 40 watts after 2400 s of electrical energy supply. This value can be increased by increasing the heat transfer surface area. This study, taking advantage of the excellent thermophysical properties of graphene, will contribute to other studies conducted in this field.
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