Numerical analysis on flow and performance characteristics of a small-scale solar updraft tower (SUT) with horizontal ab
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Numerical analysis on flow and performance characteristics of a small‑scale solar updraft tower (SUT) with horizontal absorber plate and collector glass Ramakrishna Balijepalli1 · V. P. Chandramohan1 · K. Kirankumar1 · S. Suresh2 Received: 25 October 2019 / Accepted: 7 July 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract A numerical analysis has been performed to examine and assess the flow and performance characteristics of the solar updraft tower (SUT) power plant. A realistic domain (geometry and mesh) of the flow model was generated and simulations were run with the help of ANSYS FLUENT 16.0 CFD package. A turbulent, realizable (k–ε) and discrete ordinates radiation techniques were taken into consideration to solve the governing equation. The maximum air velocity of 3.27 m s−1 was noticed at 200 mm above the chimney base (CB). The mean velocity at CB was 1.8 m s−1. The highest air temperature of the absorber plate was 323 K, and it was at the centre of the absorber plate. The average air temperature inside the setup was 306.7 K. The power generated from the plant, chimney efficiency and overall efficiency of the SUT setup were evaluated to be 0.38 W, 0.018% and 0.005%, respectively. 24% velocity increase and 70% power output increase were noticed when solar flux increased from 650 to 1150 W m−2. Exergy analysis was performed. The results were compared with existing studies and were found to be in good agreement. Keywords Solar updraft tower · Turbulent model · Numerical · Performance characteristics · Horizontal absorber plate and glass List of symbols a Absorption (m−1) A Cross-sectional area (m2) C Coefficient C1, C2, C3 Constant for k–ε model CP Specific heat of air (J kg−1 K−1) CB Chimney base CFD Computational fluid dynamics D Diameter DO Discrete ordinates FVM Finite volume method g Acceleration due to gravity (m s−2) H Height (or) collector inlet gap (m) I Solar intensity (W m−2) * V. P. Chandramohan [email protected] 1
Department of Mechanical Engineering, National Institute of Technology Warangal, Warangal, Telangana State 506 004, India
Department of Mechanical Engineering, National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamilnadu 620 015, India
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k Turbulent kinetic energy (m2 s−2) P Power output (W) Q Volumetric flow rate of air (m3 s−1) ⃗r Position vector r Radial coordinate Ra Rayleigh number RTE Radiative transfer equation ⃗s Direction vector SUT Solar updraft tower T Temperature (K) u, v, w Velocity components (m s−1) z Axial coordinate Greek symbols α Thermal diffusivity (m2 s−1) β Coefficient of thermal expansion (K−1) ε Rate of dissipation of turbulent energy (m2 s−3) μt Turbulent viscosity (m2 s−1) ΔT Temperature difference (K) Δp Relative total pressure (Pa) υ Kinematic viscosity (m2 s−1) ρ Density (kg m−3) μ Dynamic viscosity (Pa s)
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ϕ Phase function (sr−1) dΩ′ Solid angle (sr) λ Wave length (m) η Efficiency (%) σs Scattering coefficient σ Stephen Boltzmann constant δk Turb
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