Heat Transfer Modelling and Analysis of Volumetrically Heated Nanofluid Filled Enclosures

Abstract

Radiation-driven transport mechanisms are ubiquitous in many natural flows and industrial newlineprocesses. To mimic and to better understand these processes, recently, radiatively heated newlinenanofluid filled enclosures (NFEs) have been extensively researched. The present work is newlineessentially a determining step in quantifying and understanding the transport mechanisms newlineinvolved in such enclosures irradiated from top and bottom in laminar flow situation. In newlineparticular, attempt is made to develop detailed theoretical modelling frameworks for NFEs in newlinesurface-mixed-volumetric absorption modes. The governing conservation equations are newlinesolved numerically using finite volume approach and the temperature and flow field have newlinebeen found through implementation of SIMPLE algorithm in MATLAB. newlineFirstly, NFEs irradiated from top, with adiabatic, and isothermal (through convective) newlineboundaries have been analyzed under different nanoparticles volume fractions (and incident newlineflux values) to decipher the fundamental limits of sensible heat storage and thermal newlinedischarging capacities respectively. Results shows quotNFEsquot in volumetric absorption mode newline(i.e., at low nanoparticles volume fraction) attains higher sensible heat storage (8% - 20% newlinehigher) and thermal discharging (13% - 58% higher) capacities than in the corresponding newlinesurface absorption mode (i.e., at high nanoparticles volume fraction). Moving further, NFEs newlineirradiated from bottom have been analysed to understand the temperature and flow fields in newlinesituation ranging from quotvolumetricquot to quotmixedquot to quotsurfacequot absorption modes, including the newlineeffects of nanofluid optical depth, inclination angle of enclosure, incident flux, and boundary newlineconditions (adiabatic and isothermal). Under adiabatic boundary conditions, steady state is newlineunconditionally achieved irrespective of the incident flux magnitude (varied between 5Wm- newline2 - 50Wm-2), enclosure inclination angle (varied between 0and#730; to 60and#730;) and mode of absorption newline(surface, mixed or volumetric). However, in case of isothermal boundaries; onset of natural newlinecon