IOSR Journal Of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 13, Issue 2 Ser. IV (Mar. – Apr. 2021), PP 43-47 www.Iosrjournals.Org DOI: 10.9790/4861-1302044347 www.iosrjournals.org 43 | Page Effect of Thickness on the Thermal Conductivities of Three Different Bulk Wood Products of Celtis Family 1 ADEKOYA Mathew Adefusika, 2 AKINBOYEWA Lawrence Olakunle, 3 FAREMI Abass Akande and 4 OYELEYE Oyenike Tosin 1 Department of Physics, Edo State University Uzairue, Edo State, Nigeria 2 Department of Physics, The Federal University of Technology, Akure, Ondo State, Nigeria 3 Department of Physics, Federal University Oye-Ekiti, Nigeria 4 Department of Forestry and Wood Technology, The Federal University of Technology, Akure, Ondo State, Nigeria Abstract The study investigated the effect of thickness on the thermal properties of three different bulk wood products of celtis family: celtis zenkeri, celtis philipensis and celtis mildreadii. Using the modified double lee’s disc apparatus incorporated with automatic data logger. The thermal conductivity of the samples obtained increase as the thickness increases. The result shows that celtis phillipensis records the highest thermal conductivity values of 0.3968Wm -1 K -`1 . The values of the thermal conductivity and thickness obtained for the samples fall within the range of (0.3337 – 0.3968) Wm -1 K -1 and (6.79 -6.88) mm respectively. This range fall within the thermal conductivity values of common insulator material used in solar collector. The particle sizes for the specific wood samples exhibit low thermal conductivity could be comparable with materials used as industrial insulators. Hence, the selected wood materials could be useful for applications in industrial insulating devices, if properly harnessed into particle sizes. Key words: Thermal conductivity, wood materials, solar devices and automatic data logger. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 10-04-2021 Date of Acceptance: 26-04-2021 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Wood is a fibrous material that cannot be over emphasized due to usefulness in our environment. In fact, wood is a raw material used for wood-based panels, pulp and paper. Wood is still an important fuel in most of the world. Moreover, wood is available in various colours and grain sizes. It is strong in relation to its weight, its insulating to heat and electricity. People have come to understand that it has so many uses and is essential for human life. The use of wooden materials for numerous purposes cannot be over emphasized. A lot of researched have been carried out on the thermal properties of bulk and particle sizes of some selected wood products for solar device applications (Oluyamo et al., 2017; Oluyamo and Adekoya, 2015; Oluyama and Bello, 2014). Thermal insulating material is an essential factor found very useful in energy storage system to minimize heat losses from the system. The selection of thermal insulating material to be consider base on the following properties such as thermal conductivity, thermal resistivity and specific heat capacity. Thermal conductivity is the amount of energy conducted through a material of unit area, and unit thickness in unit time when the difference in temperature between the faces causing heat flow is unit temperature difference. This suggest that the thermal conductivity is an essential attribute when discussed energy conserving building products. This is due to the fact that wood has exceptional heat insulation properties. (korkut et al., 2013: Oluyamo et al., 2012). Materials of high thermal conductivity are widely used in heat sink applications, whereas materials of low thermal conductivity are used as thermal insulation (Oluyamo and Adekoya, 2015). Thermal conductivity of the wood (a property of material) can be affected by the structure of the material sizes, moisture content, density, presence of defect, temperature, pressure, thickness and other factors (Ayugi et al., 2011; Oluyamo et al., 2017). Wood samples show low thermal conductivity (high insulating properties) could be used as thermal insulator compared with the major insulating material correctly being used for insulators include fibres, glass, polyurethanes, polystyrene and insulating cement. The uses of these materials have been limited because they are expensive. Furthermore, there are many local materials available for consideration as thermal insulators includes: sawdust, charcoal dust, sugarcane and fibres (Ayugi et al., 2011). However, little or no knowledge on the effect of thickness on the thermal properties have been established. The thickness played an essential part when considering the thermal properties of wooden products. Therefore, this study focuses on the effect of thickness on the thermal properties of three different bulk wood products of celtis family.