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Numerical investigation of the effect of incomplete cone-shaped agitators on improving the heat transfer of tubular heat exchangers with water/zirconium oxide nanofluid
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Ali Mohadjer1   , Mohammad Hassan Nobakhti *2 , Alireza Nezamabadi1 |
1- Department of Mechanical Engineering, Arak Branch, Islamic Azad University, Arak, Iran.
2- Department of Mechanical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran. , m.nobakhti@srbiau.ac.ir |
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Abstract: (105 Views) |
| Considering the importance of improving heat transfer in heat exchangers, the effect of simultaneous use of agitators and also zirconium oxide nanoparticles on the heat transfer of tubular heat exchanger is studied numerically. For this purpose, at first, a new type of incomplete conical agitator with two parallel rows of holes is presented. Then, using the computational fluid dynamics method, heat transfer equations have been solved in the range of Reynolds numbers 4000 to 24000 and also the amount of zirconium oxide nanoparticles from 0.01% to 0.2%. In order to increase the modeling accuracy, the nanofluid has been simulated in a two-phase form. The effect of parameters such as the number of agitators, the number of holes and the volume fraction of nanoparticles on the flow field, the average Nusselt number, the friction factor and the thermal performance coefficient have been investigated. The results show that the use of perforated agitators in the flow path leads to significant changes in the flow characteristics and heat transfer. Perforated conical agitators improve heat transfer by creating recirculation and separation currents in the presence of nanofluid as a result of disrupting the thermal boundary layer and causing more disturbance in the fluid flow during the tubular heat exchanger. The agitators presented in this research can increase the thermal performance by 76% compared to the smooth pipe if the parameters are determined properly. The maximum coefficient of thermal performance is 1.76 in the case of M=1, N=1 and Re=4000. |
Article number: 5 |
| Keywords: Incomplete conical agitators, zirconium oxide nanoparticles, two-phase model, heat transfer, thermal performance coefficient. |
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Full-Text [PDF 1575 kb]
(71 Downloads)
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Type of Study: Research |
Subject:
Heat and Mass Transfer
Received: 2023/08/27 | Accepted: 2023/11/12 | Published: 2023/12/1
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