TY - JOUR
TI - Numerical study on heat transfer characteristics of nanofluid based natural circulation loop
AU - Bejjam Ramesh Babu
AU - K Kiran Kumar
JN - Thermal Science
PY - 2018
VL - 22
IS - 2
SP - 885
EP - 897
PT - Article
AB - In this paper the steady-state analysis has been carried out on single phase  natural circulation loop with water and water based Al2O3 (Al2O3/water)  nanofluid at 1%, 3%, 5% and 6% particle volume concentrations. For this  study, a three-dimensional geometry of natural circulation loop is developed  and simulated by using the software, ANSYS (FLUENT) 14.5. Based on the Stokes  number, mixture model is adopted to simulate the nanofluid based natural  circulation loop. For the simulations, the imposed thermal boundary  conditions are: constant heat input over the range of 200-1000W with step  size of 200W at the heat source and isothermal wall temperature of 293K at  the heat sink. Adiabatic boundary condition is imposed to the riser and  downcomer. The heat transfer characteristics and fluid flow behaviour of the  loop fluid in natural circulation loop for different heat inputs and particle  concentrations are presented. The result shows that the mass flow rate of  loop fluid in natural circulation loop is enhanced by 26% and effectiveness  of the natural circulation loop is improved by 15% with Al2O3/water nanofluid  when compared with water. All the simulation results are validated with the  open literature in terms of Reynolds number and modified Grashof number.  These comparisons confidently say that the present 3-D numerical model could  be useful to estimate the performance of natural circulation loop.