Browsing by Author "Corumlu V."

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    Evaluation of Heat Transfer Mechanisms in Heat Pipe Charged with Nanofluid
    (Springer Verlag, 2019) Corumlu V.; Ozsoy A.; Ozturk M.
    The nanofluid is a colloidal solid–liquid mixture obtained by the dispersing nanoparticles with a high heat transfer coefficient in the base fluid. In general, metal, metal oxide, ceramic and magnetic nanoparticles are used in nanofluids. The nanoparticles suspended in the base fluid of heat pipes effectively increased the heat transfer rate and thermal conductivity properties of the base fluid. The nanofluids have been found to be acting much better for some problems such as sedimentation, erosion, clogging and pressure drop compared to common slurries. The energy transfer is carried out by two-phase heat transfer mechanism in heat pipes. There are many parameters and factors that have an effect in the boiling heat transfer coefficient. It is not easy to understand the positive and negative changes caused by nanofluids in this complex heat transfer mechanism. The surface geometry is a significant indicator on the boiling heat transfer mechanism. Investigation into nanofluid effects besides the surface geometry is very important in the experimental studies. In addition, it is known that nanofluids change the properties of the heater surface, apart from the thermophysical properties. The synthesis methods of nanofluids are presented in this article. Then, the physical and chemical mechanisms determining the long-term stability of nanofluids are explained in detail. Finally, some useful information about the use of nanofluids in heat pipes and pool boiling of nanofluids is given. The presented study also describes the pool boiling mechanism of nanofluids to understand the positive effects of nanofluids on the heat pipes heat transfer mechanism. © 2019, King Fahd University of Petroleum & Minerals.
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    Thermodynamic Performance Evaluation of Concentrating Solar Collector with Supercritical Carbon Dioxide (sCO2) Base Nanofluids
    (Springer, 2020) Corumlu V.; Uzun R.O.; Ozturk M.
    The use of supercritical carbon dioxide as a working fluid is an important alternative to enable the use of parabolic collectors in the high-temperature applications field. In the present paper, the effects of carbon black nanoparticles dispersed in supercritical carbon dioxide (sCO2) base fluid on the energetic and exergetic performance of parabolic trough collectors are theoretically investigated. Thermal modeling and performance analyses are performed through the developed model in the Engineering Equation Solver software. To present operating conditions of the system, all working fluids are tested under a pressure of 80 bar at a mass flow rate of 1.1 kg/s. In these analyses, the fluid inlet temperature, ambient temperature, and nanofluid concentration are determined as the variable indicators. Up to approximately working fluid inlet temperature of 705 K, the exergy efficiencies of the concentrating collectors using the sCO2 nanofluids are higher than that of the concentrating collector using the sCO2 base fluid. Additionally, the exergy efficiency increases in the systems using nanofluids with 2% and 4% concentration ratio are between 0.34–6.96% and 0.49–11.44%, respectively, according to the system using base fluid. Besides, at the working fluid inlet temperature values greater than 705 K, the exergy efficiency of the collector of using the sCO2 working fluid is found higher than the collectors using the nanofluids. However, at the same working fluid inlet temperatures, the fluid outlet temperatures of the collectors with the sCO2 nanofluids are higher than the system with sCO2 working fluid. © 2020, King Fahd University of Petroleum & Minerals.
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    Performance analysis of a novel solar energy-based combined plant for alternative fuels production
    (John Wiley and Sons Ltd, 2021) Corumlu V.; Ozturk M.
    This paper proposes the design of a new solar power-based multigeneration system for generating hydrogen, ammonia, methane, and other beneficial outputs. This combined plant consists of the solar plant, Rankine cycle, organic Rankine cycle, single-effect absorption with ejector, carbon dioxide capture, hydrogen, ammonia, methane, drying, hot, and freshwater generation plants. The overall plant is investigated utilizing the Engineering Equation Solver software. The energy and exergy efficiencies of the integrated plant are computed as 0.6689 and 0.6227. In addition, the largest exergy destructions in the system are 6924 and 4037 kW, which occur at the Rankine cycle and solar power cycle, respectively. Moreover, the thermodynamic performance of the combined plant is investigated through parametric works and the impacts of plant working conditions on the plant efficiencies are evaluated. © 2021 John Wiley & Sons Ltd.