THERMAL SCIENCE

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Ramesh Babu Bejjam

,

Kiran Kumar K

NUMERICAL STUDY ON HEAT TRANSFER CHARACTERISTICS OF NANOFLUID BASED NATURAL CIRCULATION LOOP

ABSTRACT
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.
KEYWORDS
heat transfer, natural circulation, nanofluid, computational fluid dynamics, mixture model
PAPER SUBMITTED: 2016-08-26
PAPER REVISED: 2017-02-18
PAPER ACCEPTED: 2017-02-22
PUBLISHED ONLINE: 2017-04-08
DOI REFERENCE: https://doi.org/10.2298/TSCI160826087B
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2018, VOLUME 22, ISSUE Issue 2, PAGES [885 - 897]
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Numerical study on heat transfer characteristics of nanofluid based natural circulation loop

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