Numerical Investigation of Heat Loss in Nano-Fumed Silica Reinforced Styrene Acrylonitrile Hydrophobic Thermo-Sheath for Heat Inhibition in Hydronic Boiler

Three dimensional chain-like spherical nanoparticles of nano-fumed silica (NFS) were successfully incorporated in poly styrene acrylonitrile (SAN) matrix through simple spray coating technique. Morphological and topographical analyses revealed well dispersed domains of irregularly patterned clustered NFS microneedles in SAN matrix, followed by hydrophobicization with water contact angle of 115.2°. Incorporation of NFS in SAN matrix reduced the thermal conductivity by 53% with utmost loading of 40 wt% NFS mathematically computed by percolation model and also imparted the visible light translucency to the composite. SAN/NFS polymer-filler solution with workable viscosity of 140 cp was spray coated on horizontal plain copper pipe in order to obtain thermo-sheath with low thermal conductivity (0.07 Wm^–1K^–1), visible light translucency and hydrophobicity. Heat loss through horizontal plain and thermo-sheath insulated copper pipe was experimentally and numerically investigated by a combination of conduction, convection and radiation components. The results showed that insulated pipe dramatically reduced the heat loss by 47% with insulation thickness of 1.5 mm compared to the plain pipe. The present study systematically demonstrates the feasibility of NFS reinforced SAN thermo-sheath as an effective and economic thermal insulation for heat inhibition in dissemination pipes of hydronic boilers for efficient thermal management and energy utilisation.