Ngunzi Veronica K, Kanali Christopher L, Kituu Gareth M, Ronoh Erick K
Department of Agricultural and Biosystems Engineering, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.
Heliyon. 2024 Dec 4;10(24):e40875. doi: 10.1016/j.heliyon.2024.e40875. eCollection 2024 Dec 30.
Fuelwood is the primary source of heat energy for tea processing, but its availability is declining due to population growth and logging restrictions. This study aimed to optimize the economics of biomass fuel mixtures for tea processing boilers by integrating macadamia nutshells as a supplementary fuelwood. The objective was to develop a cost-effective fuel mix strategy using Response Surface Methodology (RSM) and MATLAB simulations. The methodology involved proximate and ultimate analyses to assess the energy potential of fuelwood and macadamia nutshells. Various scenarios of moisture content and wood availability were simulated to determine the necessary quantities of macadamia nutshells to address fuelwood shortages. RSM was then applied to optimize the fuel mix by minimizing costs while maximizing energy efficiency. Key findings revealed that macadamia nutshells have a higher bulk density (680-745 kg/m³) and lower moisture content (7.86-10 %) than eucalyptus wood (322-358 kg/m³, 15-50 % moisture content). Additionally, macadamia nutshells have a superior calorific value (21,296.56 kJ/kg) compared to eucalyptus (18,765.24 kJ/kg), though they are more expensive (USD 0.10/m³ vs. USD 0.04/m³). The regression analysis showed that moisture content significantly increased fuel costs (18 % per unit increase), while wood availability reduced costs by 17 % per unit increase. The quadratic model (R = 0.9995) confirmed these interactions. The study supports the use of macadamia nutshells as a viable alternative or supplementary fuel source, enhancing the sustainability of tea processing operations.
薪柴是茶叶加工热能的主要来源，但由于人口增长和伐木限制，其供应量正在下降。本研究旨在通过将澳洲坚果壳作为补充薪柴，优化茶叶加工锅炉生物质燃料混合物的经济性。目标是使用响应面法（RSM）和MATLAB模拟制定具有成本效益的燃料混合策略。该方法包括进行近似分析和元素分析，以评估薪柴和澳洲坚果壳的能源潜力。模拟了各种含水量和木材供应量的情景，以确定弥补薪柴短缺所需的澳洲坚果壳数量。然后应用响应面法通过最小化成本同时最大化能源效率来优化燃料混合物。主要研究结果表明，澳洲坚果壳的堆积密度（680 - 745千克/立方米）高于桉木（322 - 358千克/立方米），含水量（7.86 - 10%）低于桉木（15 - 50%）。此外，澳洲坚果壳的热值（21,296.56千焦/千克）高于桉木（18,765.24千焦/千克），尽管其价格更高（0.10美元/立方米对0.04美元/立方米）。回归分析表明，含水量显著增加燃料成本（每单位增加18%），而木材供应量每单位增加可降低成本17%。二次模型（R = 0.9995）证实了这些相互作用。该研究支持将澳洲坚果壳作为一种可行的替代或补充燃料来源，提高茶叶加工运营的可持续性。
