Numerical investigation of laminar flow of biological nanofluid in a rifled tube using two-phase mixture model: first-la
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Numerical investigation of laminar flow of biological nanofluid in a rifled tube using two‑phase mixture model: first‑law and second‑law analyses and geometry optimization Amin Shahsavar1 · Majid Jafari1 · Sara Rostami2,3 Received: 18 February 2020 / Accepted: 10 July 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The impetus of this numerical investigation is to explore the performance aspects of laminar forced convection flow of biologically synthesized water–silver nanofluid inside an internally spiral-ribbed heat exchanger tube from both the first and second laws of thermodynamics perspectives. The two-phase mixture model is used to perform the required simulations. The impacts of the volume concentration of nanoadditives (φ), Reynolds number (Re) as well as the width (W), height (H) and pitch (P) of the ribs on the hydrothermal aspects and irreversibility behavior of the nanofluid are assessed, and the results are compared with the findings of smooth tube. It was found that the use of nanofluid and the use of rifled tube instead of water and smooth tube, respectively, are suitable ways to improve system performance from both the first and second laws of thermodynamics perspectives. Moreover, it was reported that the best hydrothermal performance of the nanofluid through the rifled tube occurs at φ = 1%, Re = 2000, W = 3 mm, H = 1 mm, P = 4 mm, while the minimum total irreversibility in the flow of water–silver nanofluid inside a rifled tube occurs at φ = 1%, Re = 2000, W = 3 mm, H = 0.5 mm, P = 4 mm. Keywords Biological nanofluid · Heat transfer · Irreversibility · Internally spiral-ribbed heat exchanger tube · Rifled tube List of symbols Be Bejan number (–) cp Specific heat capacity (J kg−1 K−1) dp Nanoparticle diameter (m) Dh Hydraulic diameter of tube (m) f Friction factor (–) fdrag Drag coefficient (–) FOM Figure of merit (–) g Gravitational acceleration (m s−2) H Height of ribs (m) h Convective heat transfer coefficient (W m−2K−1) k Thermal conductivity (W m−1 K−1) L Length of tube (m) * Amin Shahsavar [email protected] * Sara Rostami 1
Department of Mechanical Engineering, Kermanshah University of Technology, Kermanshah, Iran
Laboratory of Magnetism and Magnetic Materials, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam
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Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
P Pitch of ribs (m) p Pressure (Pa) PEC Performance evaluation criterion (–) q″ Heat flux (W/m−2) Re Reynolds number (–) ′′′ Ṡ g,f Local fluid friction irreversibility rate (W m−3 K−1) ̇S′′′ Local heat transfer irreversibility rate (W m−3 K−1) g,h ′′′ Ṡ g,t Local total irreversibility rate (W m−3 K−1) Ṡ g,f Global fluid friction irreversibility rate (W K−1) Ṡ g,h Global heat transfer irreversibility rate (W K−1) Ṡ g,t Global total irreversibility rate (W K−1) T Temperature (K) V Velocity (m s−1) Vdr Drift velocity (m s−1) W Width of ribs (m) Greek letters φ Volume concentration of nanofluid (%) μ
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