WSEAS Transactions on Heat and Mass Transfer
Print ISSN: 1790-5044, E-ISSN: 2224-3461
Volume 17, 2022
Compelling Augmentation of Laminar Natural Convection from Vertical Plates to Binary Gas Mixtures Formed with Light Helium and Selected Heavier Gases
Authors: ,
Abstract: The present study addresses a remarkable behavior of certain binary gas mixtures in connection to laminar natural convection along a heated vertical plate at constant temperature. The binary gas mixtures are formed with light gas helium (He) as the primary gas and selected heavier secondary gases. The heavier secondary gases are nitrogen ($$N_2$$), oxygen ($$O_2$$), xenon (Xe), carbon dioxide ($$CO_2$$), methane ($$CH_4$$), tetrafluoromethane ($$CF_4$$) and sulfur hexafluoride ($$SF_6$$). The central objective in the work is to investigate the attributes of the set of seven He‒based binary gas mixtures in reference to heat transfer enhancement with respect to helium (He) and air. From heat convection theory, four thermophysical properties: viscosity η, density ρ, thermal conductivity λ, and isobaric heat capacity $$C_p$$ affect the thermo‒buoyant convection of fluids. It became necessary to construct a particular correlation equation consigned to the set of seven He‒based binary gas mixtures, which operate in the Prandtl number closed sub‒interval [0.1, 1]. The heat transfer rate $$Q_{mix}$$ with the seven He‒based binary gas mixtures from the vertical plate involves four thermophysical properties: density $$ρ_{mix}$$, viscosity $$η_{mix}$$, thermal conductivity $$λ_{mix}$$, and isobaric heat capacity $$C_p$$, mix that vary with the molar gas composition w. A case study is performed to elucidate the unique characteristics of the modified convective heat transport that the set of seven He‒based binary gas mixtures bring forward as compared to the convective heat transport of pure He and air. It was found that the He+SF6 binary gas mixture renders an absolute maximum heat transfer enhancement ratio that is 39 times higher than the heat transfer enhancement ratio provided by pure He and 78 times higher than air.
Search Articles
Keywords: Natural convection, vertical plate, laminar boundary layer flow, light helium is the primary gas, selected heavier gases are the secondary gases, binary gas mixtures, heat transfer enhancement ratio
Pages: 166-187
DOI: 10.37394/232012.2022.17.19