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Convective Heat Transfer in Heat Exchangers Using Nanofluids: A Review

Reddy Goda Sreenivasulu, Kalaivanan Ramasamy, Kumar Rampelli Uday, Krishna Varma K. P. V.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 3

193--201

EN

Enhancing the Convective heat transfer in the carrier fluids, by augmenting the thermal conductivity in fluids, with nano particles is one of the passive techniques. Enhancement in the thermal conductivity in the carrier fluids can be achieved by suspending particles of nano-size into the base fluids, such colloidal suspensions are called as nanofluids. Nanofluids are proven fluids which improve the convective transfer of heat in the base fluids in the heat exchangers. But still, there are lot of challenges that are existing in understanding the mechanisms of enhancement of convective heat transfer for large scale applications. In this work, an attempt is made to summarize recent advancements on augmentation of convective heat transfer in heat exchangers in turbulent flows using various nanofluids and present various setbacks for the development of nanofluids for critical applications.

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Artificial Neural Network Technique for Estimating the Thermo-Physical Properties of Water-Alumina Nanofluid

Ravi Babu Sajja, Krishna Varma K. P. V., Mohan Kunapuli Siva Satya

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 2

97--106

EN

With its superior thermo-physical characteristics to the carrier fluid, nanofluid is the most impactful heat transfer fluid. Thermal conductivity, density, viscosity, specific heat, coefficient of volumetric expansion, and other thermo-physical parameters play an important part in the thermal management of any heat transfer application. This thermal management governs the service life of an equipment or apparatus, which dissipates heat during its operation. If the equipment is well-managed thermally, then its service life will be extended. Otherwise the equipment stops functioning due to excess heat. Thermo-physical properties of nanofluid vary with the change in the concentration of nanoparticles. Estimation of the properties with the varying concentrations of the nanoparticles is time consuming and is economically not viable. There were many empirical models available in the literature for determining the thermo-physical properties of nanofluids. However, each model provides different values of thermo-physical properties and choosing the best model among the models available is a complex task. In this regard, to avoid the complication in choosing the best model, and in order to envisage the thermo-physical properties of the nanofluid, the Artificial Neural Network (ANN) technique was used. This technique is widely used among the researchers for various applications. The ANN approach was utilized in this work to estimate viscosity and thermal conductivity of water-based Al2O3 nanofluid for volume fractions between 0.01% and 0.1%. For thermal conductivity, mean square error (MSE) was observed as 4.504e-09 and for viscosity, it was observed as 6.4742e-09. Training times were 5 seconds and 4 seconds for thermal conductivity and viscosity datasets, respectively.

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Comparative Analysis of Effect of Wind Loads with Variation in Altitude and Angle of Inclination of Wind Direction on Solar Panels

Surendra Reddy P., Swapna K., Kiran Kumar G., Krishna Varma K. P. V.

Ecological Engineering & Environmental Technology

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2021

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Vol. 22, iss. 6

61--68

EN

Solar panels are used in wide range of applications like power generation, automobiles, electronic devices etc. They are trending devices which develop power from abundantly available solar energy. In spite of this advantage, they are affected by wind loads, which result in wind induced loading. Determining this is very essential because, the drag and lift forces applied on the solar panels due to the wind loads play a crucial role in the accomplishment of performance in the solar panels. In this work, an attempt was made to carry out a comparative analysis of the effect caused by the wind forces on different array sizes, altitudes, orientation of the solar panels at different wind speeds (5 m/s, 25 m/s) and at different inclination angles the wind (0°, 45°, 135° and 180°. The ultimate objective of this work was to analyze the effect caused by wind forces based on these combinations of the parameters. Different shapes of solar panels like rectangular and hexagonal shaped were analyzed for normal and optimized conditions. Moreover, wind load analysis was carried out for different altitudes like on the ground and on the roof top. The outcomes depict that the wind forces on front region of the conventional solar panels is higher when compared to the optimized solar panel.