Exergy and energy amelioration for parabolic trough collector using mono and hybrid nanofluids

Abstract

Energy and exergy efficiency amelioration of the parabolic trough has taken high interest since recent years, especially when nanofluid used as an enhancement category. This paper aimed to improve LS-2 parabolic trough model and compare the enhancement effect that occurred using different mono and hybrid nanofluids. Inserting mono nanoparticles of Al 2 O 3 , CeO 2 , CuO, and hybrid combinations of Al 2 O 3 with CeO 2 , or CuO nanoparticles in a Syltherm 800 was investigated by five different cases. The investigation was presented under total volume fraction 4% for all nanofluids and mixing fraction 50:50 for the hybrid types in order to facilitate the analysis and compare various results at the same conditions. Those cases and their comparisons were solved using MATLAB Symbolic tools under turbulent flow regime and variable inlet temperature to present wide domain behavior for the energy and exergy efficiency, Nusselt number, heat transfer coefficient, and pressure drop, whereas the analytical solution of the energy balance equation was taken from the literature and improved to cover the mentioned cases. Moreover, the results were compared with previous researches that used different thermal fluid and showed high accuracy behavior with low deviation. Therefore, the findings showed that Al 2 O 3 and CeO 2 hybrid nanofluids were more efficient than using of both Al 2 O 3 and CuO hybrid nanofluids and any mono nanofluids contain the same nanoparticles. The maximum enhancement of thermal and exergy efficiency of using Al 2 O 3 and CeO 2 hybrid nanofluids was 1.09% and 1.03%, respectively, whereas it was enhanced by 167.8% and 200.7% for the Nusselt number and heat transfer coefficient, respectively. Also, the hybrid nanofluids have higher advantage over the mono nanofluids by presenting lower pressure drop values. Finally, the assessment of efficiency variation affected by thermal properties of the nanoparticle was presented under optimum temperature equal to 575 K.

Experimental investigation of using graphene nanoplatelets and hybrid nanofluid as coolant in photovoltaic thermal systems

“…(1) Where is the base fluiddensity,φis the volume concentrations of the dispersed fluid, and is the nanoparticles' density; otherwise, the density of the hybrid nanofluid is obtained using the following alternative formula(Al-Oran et al [24]):…”

“…(5) Here,ρ denotesthe density in , Cp represents the specific heat in kJkg -1 K -1 , and φ showsthe volumetric ratio of nanoparticles in a base fluid. The subscripts f, n, and nfre spectively represent base fluid, nanoparticles, and nanofluid.The heat capacity of HyNF is obtained using the following main formula(Al-Oran et al [24]): (6) Maxwell-Garnet model is used to calculatethe nanofluids' thermal conductivity by using the following model [27]:…”

“…Also, the thermal conductivity of HyNF was represented by the following equation(Al-Oran et al [24]).…”

Thermal Conductivity of Al2O3 and CeO2 Nanoparticles and Their Hybrid Based Water Nanofluids: An Experimental Study

“…Thermal conductivity is an important thermal transport property to which the applicability of using the nanofluids is attributed as it influences the heat transfer performance. However, this property considered as a major key to enhancing the nanofluids heat transfer performance in many heat exchange systems, which are included the boiling process [4][5][6], cooling of electronic devices [7,8], solar energy [9], geothermal energy [10], etc. Hence, enhancement of the thermal conductivity of the working fluids could offer a good opportunity to increase the heat transfer rate, which, in turn, improves the thermal efficiency of the heat exchange systems.…”

Statistical estimation of hourly diffuse radiation intensity of Budapest City

“…10 Recently, solar energy is considered one of the most renewable energy resources that are utilized as an alternative to fossil fuel energy and have an apparent effect on the economic and environmental issues 11 . To determine the applicability of using any solar system in any place, solar radiation components—direct, global, and diffuse—must be assessed as a first step, which in turn has a positive effect in increasing the reliability and economic feasibilities of different solar energy applications 12‐14 . Numerous techno‐economic studies, as well as optimization studies of solar energy systems, have been presented in the literature where their analysis highly depends on the accuracy of the solar resources 15‐19 .…”