Influence of Surface Reflection (Albedo) in Simulating the Sun Drying of Paddy Rice

Abstract

The sun drying of agricultural products is a complicated process involving heat transfer, mass transfer, and variable weather conditions. Surface reflection (albedo), a crop’s radiative property, plays an essential role in energy balance, and understanding its contribution can improve the thermal analysis. In this study, field experiments were conducted in the Philippines to explore the influence of surface albedo on the sun drying of paddy rice. First, we implemented energy and mass balance equations in a transient model with the surroundings using a graphical programming language in Matlab/Simulink®. Second, we identified the influence of albedo on the sun drying model by using a sensitivity analysis. Third, we investigated the relationship of paddy rice albedo and the solar zenith angle. Lastly, we integrated the albedo function into the sun drying model. The simulation outputs were validated with field experiments. A better estimation of the measured exit temperature and instantaneous mass were obtained when a variable albedo was applied. This study makes clear that introducing a variable albedo has a positive impact on model improvement. This information is important for application in solar drying technologies, so that the drying process can be better assessed.

Electronic Structure and Optical Spectra of Halide Perovskites A2BCl6 [(A = Cs; B = Se, Sn, Te, Ti, Zr) and (A = K; B = Pd, Pt, Sn)] for Photovoltaic and Optoelectronic Applications

“…The ability of a surface to send back radiation is characterized by its reflectivity R ( ω ). [ 100 ] A material's reflectivity is proportional to its metallicity; therefore, the R ( ω ) value is the largest for negative ε 1 ( ω ). R ( ω ) is a crucial coefficient for the appliance of antireflective surfaces for harvesting solar light.…”

CFD-Simulink Modeling of the Inflatable Solar Dryer for Drying Paddy Rice

“…As found in a previous study [34], the reflectance is dependent on the zenith angle (θ): The change over time of the energy stored in the product results from the radiant energy on the product, the convective heat exchange between the product and the drying air, the radiant heat exchange with the cover, the environment, and the thermal losses to the ground as well as the energy required in the unit of time to evaporate the moisture. The energy balance is presented as:…”

“…As the ISD does not have an insulation material, the influence of the ground layers i (asphalt, soil, and absorber) is considered in the model following our previous research [34], in which the sun drying practice was modeled. The energy balance of the bottom layers under the ISD is driven by heat conduction.…”