INVESTIGATION OF THERMOHYDRAULIC PERFORMANCE AND ENTROPY GENERATION IN A TUBE WITH GRAPHENE NANOPARTICLE REINFORCED NANOFLUID AND CONICAL INNER RIBS


Thesis Type: Doctorate

Institution Of The Thesis: Erciyes University, Mühendislik Fakültesi, Makina Mühendisliği, Turkey

Approval Date: 2020

Thesis Language: Turkish

Student: Orhan Keklikcioğlu

Supervisor: Veysel Özceyhan

Abstract:

In this thesis, the effects of the use of internal ribs and nanofluids, which are among the techniques used to increase the performance of heat exchangers, on the thermohydraulics performance and entropy production of a heat exchanger tube were investigated experimentally and numerically. The specifically designed helically coiled conical internal ribs were produced in two different distance ratios (P/D = 2 and 3), and have three different tube layouts: Divergent, Divergent-Convergent, Convergent. Graphene nanoparticle, which stands out with its high thermal conductivity and high stability values compared to other nanoparticles, with three different weight ratios, % 0.5, 0.75 and 1 was added in base fluid that comprises three different water-ethylene glycol mixing ratios, after created nanofluid thermophysical properties of concentrations were examined. It was determined that the experimental and numerical studies were compatible with each other for the Reynolds number varies in the range of 4000-27,000. It was acquired that the Nusselt number increased depending on both the use of internal ribs and the use of nanofluid, the friction coefficient increasesd depending on the use of internal ribs, but it did not show a radical change in the use of nanofluids. The individual performances of both passive techniques were low compared to their combined use performances, the highest thermohydraulics performance value was provided by %100 Su-GnP nanofluid-Divergent-P/D=2 conical internal rib compound configuration as 1.72 in the 6283 Reynolds number, the dimensionless entropy production number value was realized as 0.42 for the 25,451 Reynolds number, in the same configuration.