Impact of Fusion Temperature on Hydrothermal Features of Flow within an Annulus Loaded with Nanoencapsulated Phase Change Materials (NEPCMs) during Natural Convection Process
Seyyed Masoud Seyyedi, M. Hashemi‐Tilehnoee, Mohsen Sharifpur
Abstract
A new type of nanofluids is nanoencapsulated phase change materials (NEPCMs), where nanoparticles are made of a shell and a core. In the current study, characteristics of free convection flow, entropy generation, and heat transfer of NEPCMs in an enclosure are investigated. The enclosure is an annulus between concentric horizontal circular and square cylinders with a porous medium. The governing equations (i.e., continuity, energy, and momentum) are written in the nondimensional form and then numerically solved by the control volume finite element method (CVFEM). The results of the validation are in good agreement with those of the literature. The effects of decision variables on the entropy generation number and the average Nusselt number are investigated. The outcomes discovered that there is a maximum for <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:msub> <a:mrow> <a:mtext>Nu</a:mtext> </a:mrow> <a:mrow> <a:mtext>ave</a:mtext> </a:mrow> </a:msub> </a:math> and a minimum for <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:msub> <c:mrow> <c:mi>N</c:mi> </c:mrow> <c:mrow> <c:mtext>gen</c:mtext> </c:mrow> </c:msub> </c:math> at <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:msub> <e:mrow> <e:mi>θ</e:mi> </e:mrow> <e:mrow> <e:mi>f</e:mi> </e:mrow> </e:msub> <e:mo>=</e:mo> <e:mn>0.4</e:mn> </e:math> for each value of the Stefan number. Also, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M4"> <g:msub> <g:mrow> <g:mtext>Nu</g:mtext> </g:mrow> <g:mrow> <g:mtext>ave</g:mtext> </g:mrow> </g:msub> </g:math> and ECOP increase by 8.8% and 24.8%, respectively, while <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" id="M5"> <i:msub> <i:mrow> <i:mi>N</i:mi> </i:mrow> <i:mrow> <i:mtext>gen</i:mtext> </i:mrow> </i:msub> </i:math> decreases by 12.8% when <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" id="M6"> <k:mi>ϕ</k:mi> </k:math> increases from 0 (pure fluid) to 0.05 at <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" id="M7"> <m:msub> <m:mrow> <m:mi>θ</m:mi> </m:mrow> <m:mrow> <m:mi>f</m:mi> </m:mrow> </m:msub> <m:mo>=</m:mo> <m:mn>0.4</m:mn> </m:math> .