Title: Modeling the Effect of Thermal Treatment on Hardness of Medium Cashew Nut Shells
Authors: Jimeshio, Joseph Gberindyer, Ekemube Raymond Alex, Nyamkyume Felix Terkula, Paul, Anaticha Miracle
Volume: 10
Issue: 9
Pages: 105-114
Publication Date: 2026/09/28
Abstract:
Thermal processing has become an important pathway for mechanical modification of agricultural by-products for value addition and sustainable utilization. Cashew nut shell, an abundant lignocellulosic residue in Nigeria, possesses engineering properties that can be modified through controlled thermal treatment. This study investigated the resulting impact of temperature and time interactions on the hardness of medium cashew nut shell accessions and established an empirical model using the Buckingham Pi theorem. Medium cashew nut shells sourced from the Cocoa Research Institute of Nigeria (CRIN) were subjected to thermal treated at 200, 250, and 300°C for 30, 60, and 90 mins. The hardness and compressive strength were determined using a universal testing machine (UTM), while the physical and thermal properties including density; moisture content, thermal conductivity, and specific heat capacity were determined using standard engineering methods. Dimensional analysis was used to establish dimensionless ?-terms, which formed the prediction equation for hardness: H=?(??K/T?). The generalized reduced gradient (GRG) nonlinear Excel solver was used to estimate the model constant (?) in order to minimize the sum of squared errors. The model's predictive capacity was confirmed by validation, with a low RMSE of 0.86 and a high RPD of 28.6, indicating an excellent predictive capacity. The outcome showed that shell hardness is significantly changed by thermal treatment, and the devised model successfully accounts for these changes. This technique has potential for improving thermal processing in agro-industrial applications such as cashew shell valuation.