Browsing by Author "Ndiritu, Hiram"

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  • Publication
    Publication
    Optimization of the Performance of Hybrid Solar Biomass Dryer for Drying Maize Using ANSYS Workbench
    (Journal of Energy Research and Reviews, 2020-02-03) Aukah, Jackis; Muvengei, Mutuku; Ndiritu, Hiram; Onyango, Calvin
    In this paper ANSYS workbench was used to optimize the performance of hybrid solar biomass dryer for drying shelled maize in order to find the optimal operating input variables when the air temperature within the drying chamber set within the permissible range at reasonably high flow velocity. Hybrid Solar dryer with biomass as a source of fuel for auxiliary heating during absence or low solar insolation is a feasible option for small scale maize farmers [1]. At times high temperatures are induced in this dryer which may result in grain fissures and breakage during milling, thus reducing the grain quality. Optimization results indicate that in order to keep the air temperature within drying chamber to permissible range [2], the air velocity at collector inlet and biomass heat exchanger outlet should be improved to 3 m/s and 2.8 m/s respectively while the capacity of the biomass heat exchanger should also be enhanced to provide hot air at 85°C. It be concluded from the study that HSBD is suitable for drying maize as well as other agricultural products since continuous interrupted drying can be achieved. The capability of the dryer to maintain uniform temperature and air flow within the drying chamber enable high quality dried products within a short duration.
  • Publication
    Publication
    Prediction of Airflow and Temperature Distribution in Hybrid Solar-Biomass Dryer using Computational Fluid Dynamics
    (JOURNAL OF SUSTAINABLE RESEARCH IN ENGINEERING, 2018-09-15) Aukah, Jackis; Muvengei, Mutuku; Ndiritu, Hiram; Onyango, Calvin
    Hybrid solar-biomass dryers present a viable option for drying maize since continuous drying can be achieved. However,non-uniform drying of the product may occur in the drying chamber due to poor airflow distribution. Several studies have beenreported on modeling of solar dryers for drying of agricultural products but most researchers use one dimensional models basedon thermal analysis to simulate the drying process but this approach can only describe the flow variable in one defined directionalong the domain and therefore, cannot effectively reveal information on air flow patterns which is considered crucial foroptimization process. Three dimensional approach that provides a more realistic simulation of the drying process is necessary foroptimization of the performance of the dryer. The aim of this study was to develop a mathematical model for predicting thetemperature and air velocity distribution in hybrid solar biomass dryer. The model consists of the full set of partial differentialequations that describe the conservation of mass, momentum and heat inside the dryer. The standard model was used to describeturbulence in addition to the governing conservation equations. Simulation was done using ANSYS CFX which is a general purposeComputational Fluid Dynamics (CFD) package. The simulated airflow pattern and temperature distribution on the horizontal andvertical planes in the drying chamber was analyzed and the result revealed spatial homogeneity of drying air condition. The modelwas validated experimentally and the results showed a reasonable agreement between the experimental and simulated results witha small variation of about 0.7 0 C. This indicate that the model prediction was reasonably accurate.