Thermal Analysis of a Passive Solar Dryer for Paddy Rice Drying

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This paper presents the thermal analysis of a passive solar dryer for paddy rice drying. The dryer, which was designed with a capacity of two tonnes of paddy rice per batch, was deployed and test run in a rural agrarian community. The thermal analysis of the dryer was carried out using a computational fluid dynamic (CFD) model of the system. The system’s two-dimensional continuity, momentum, and energy equations were developed subject to suitable boundary and initial conditions. The CFD model was executed for a day for which the available experimental data was 11 MJ/day of solar irradiance, mean wind velocity of 0.0186 m/s, and mean ambient temperature of 20°C. The simulation was carried out for nine different mesh sizes ranging from extremely coarse (5378 domain elements with 378 boundary nodes) to extremely fine (56153 domain elements with 1385 boundary nodes). The simulation time for the extremely coarse mesh size was 52.32 minutes, while that for the extremely fine was 180.95 minutes. The temperature, velocity, and pressure distributions of the drying air within the drying chamber were determined for each mesh size. From these, their mean values at given times and the day were calculated. It was found that the finer mesh sizes (33134 domain elements with 1004 boundary nodes to 56153 domain elements with 1385 boundary nodes) gave the same results which agreed with experimental data. The results show that the drying process is effective in harnessing solar energy to heat the chamber with the chamber temperature reaching a maximum temperature of approximately 336 K and an average drying chamber temperature of 315.6K. Possible design improvements to the system are suggested, including the incorporation of forced air circulation and phase change material energy storage.

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111-120

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February 2026

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© 2026 Trans Tech Publications Ltd. All Rights Reserved

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[1] Ekechukwu O.V, Norton B, Design and measured performance of a solar chimney for natural circulation solar-energy dryers, Renewable Energy. 1997: 81-90. doi:10.1016/0960-1481(96) 00005-5.

DOI: 10.1016/0960-1481(96)00005-5

Google Scholar

[2] Kalogirou S.A, Solar energy engineering, Academic Press. 2014: 1-49.

Google Scholar

[3] Chavan A, Vitankar V, Mujumdar A, Thorat B, Natural convection and direct type (NCDT) solar dryers: A review, Drying Technology. 2020; 39(13): 1969-1990. https://doi.org/10.1080/ 07373937.2020.1753065

DOI: 10.1080/07373937.2020.1753065

Google Scholar

[4] Okoroigwe E.C, Eke M.N, Ugwu H.U, (2013). Design and evaluation of combined solar and biomass dryer for small and medium enterprises for developing countries, Int. J. Phys. Sci. 8(25): 1341-1349.

Google Scholar

[5] Okoroigwe C.E, Evidence C.N, Florence C.O, (2015) Comparative evaluation of the performance of an improved solar-biomass hybrid dryer, Journal of Energy in Southern Africa. 25(4): 38-51.

DOI: 10.17159/2413-3051/2015/v26i4a2092

Google Scholar

[6] Mohana Y, Mohanapriya R, Anukiruthika T, Yoha K.S, Moses J.A, Anandharamakrishnan C, Solar dryers for food applications: Concepts, designs, and recent advances, Solar Energy. 2020; 208: 321-344

DOI: 10.1016/j.solener.2020.07.098

Google Scholar

[7] Khouya A, Draoui A, (2019). Computational drying model for solar kiln with latent heat energy storage: case studies of thermal application, Renewable Energy 130: 796-831.

DOI: 10.1016/j.renene.2018.06.090

Google Scholar

[8] Bal L.M, Satya S, Naik S.N, (2010) Solar dryer with thermal energy storage systems for drying agricultural food products: a review, Renewable and Sustainable Energy Review 14: 2298-2314.

DOI: 10.1016/j.rser.2010.04.014

Google Scholar

[9] Kant K, Shukla A, Sharma A, Kumar A, Jain A, (2016) Thermal energy storage based solar drying systems: a review, Innovat. Food Sci. Emerg. Technol. 34: 86-99.

DOI: 10.1016/j.ifset.2016.01.007

Google Scholar

[10] Guler H.O, Sozen A, Tuncer A.D, Afshari F, Khanlari A, Sirin C, Gungor A, (2020) Experimental and CFD survey of indirect solar dryer modified with low-cost iron mesh, Solar Energy. 197: 371- 384.

DOI: 10.1016/j.solener.2020.01.021

Google Scholar

[11] Motahayyer M, Arabhosseini A, Samimi-Akhijahani H, (2019). Numerical analysis of thermal performance of a solar dryer and validated with experimental and thermo-graphical data, Solar Energy. 193: 692-705.

DOI: 10.1016/j.solener.2019.10.001

Google Scholar

[12] Amanlou Y, Zomorodian A, (2010) Applying CFD for designing a new fruit cabinet dryer, J. Food Eng. 101: 8-15.

DOI: 10.1016/j.jfoodeng.2010.06.001

Google Scholar

[13] Darabi H, Zomorodian A, Akbari M.H, Lorestani A.N, (2015) Design a cabinet dryer with two geometric configurations using CFD, J. Food Sci. Technol. 52: 359-366.

DOI: 10.1007/s13197-013-0983-1

Google Scholar

[14] Rek Z, Rudolf M, Zun I, (2012) Application of CFD Simulation in the Development of a New Generation Heating Oven, J. Mech. Eng. 58: 134-144.

DOI: 10.5545/sv-jme.2011.163

Google Scholar

[15] Misha S, Mat S, Ruslan M.H, Sopian K, Salleh E, (2013) The Prediction of Drying Uniformity in Tray Dryer System using CFD Simulation, Int. J. Mach. Learn. Comput. 3: 419-423.

DOI: 10.7763/ijmlc.2013.v3.352

Google Scholar

[16] Mirade P, (2003) Prediction of the air velocity field in modern meat dryers using unsteady computational fluid dynamics (CFD) models, 60: 41-48.[17] Mauro A, Massarotti N, Salahudeen M, Cuomo F, Costagliola C, Ambrosone L, Romano M.R, (2018). Design of a novel heating device for infusion fluids in vitrectomy, Appl. Therm. Eng. 128: 625-636.

DOI: 10.1016/j.applthermaleng.2017.08.027

Google Scholar

[18] Norton T, Tiwari B, Sun D.W, Computational fluid dynamics in the design and analysis of thermal processes: a review of recent advances, Crit. Rev. Food Sci. Nutr. 2013; 53, 251-75.

Google Scholar

[19] Tegenaw P.D, Gebrehiwot M.G, Vanierschot M, Design and CFD Modeling of a Solar Food Drier, Euro Drying. 6th European Drying Conference, 2017: 183-184.

Google Scholar

[20] Manisha L, Shivani S.P, Pallavi A.W, Radhika S.T, Saiganesh S.B, Design and Computational Fluid Dynamics (CFD) Modelling for Solar Food Dryer, 2022; GIS Jornal. 9(7): 1511-1520.

Google Scholar

[21] Meenakshi R.R, Siva R, Uma M.C, and Krishna K.R, CFD and experimental analysis of solar crop dryer with waste heat recovery system of exhaust gas from diesel engine, IOP Conf. Series: Earth and Environmental Science 2018; 164: 012010. doi:10.1088/1755-1315/164/1/ 012010.

DOI: 10.1088/1755-1315/164/1/012010

Google Scholar

[22] Iloeje O.C, Ekechukwu O.V, Ezeike G.O.I, Design, Construction and Test Run of A Two-Tonne Capacity Solar Rice Dryer With Rice-Husk-Fired Auxiliary Heater, Internal Report, International Centre For Theoretical Physics (ICTP), Trieste, Italy. 1993: 1-8.

Google Scholar

[23] Sharma, V.K, Sharma S, Ray R.A, Garg H.P, (1986) Design and performance studies of a solar dryer suitable for rural applications, Energy Conversion and Management 26(1): 111-119.

DOI: 10.1016/0196-8904(86)90040-3

Google Scholar

[24] Barnwal P, Tiwari G.N, (2008) Grape drying by using hybrid photovoltaic-thermal (PV/ T) greenhouse dryer: an experimental study, Solar Energy. 82: 11311144.

DOI: 10.1016/j.solener.2008.05.012

Google Scholar

[25] Pragnan L, Rahul K, Rajat S, Jatin P, Numerical investigation of phase change material assisted indirect solar dryer for food quality preservation, International Journal of Thermofluids 2023; 18: 100305

DOI: 10.1016/j.ijft.2023.100305

Google Scholar

[26] Petros D.T, Mekonnen G.G, Maarten V, On the comparison between Computational Fluid Dynamics (CFD) and lumped capacitance modeling for the simulation of transient heat transfer in solar dryers, Solar Energy. 2019: 1-19

DOI: 10.1016/j.solener.2019.04.024

Google Scholar

[27] Mulatu C. Gilago, Vishnuvardhan Reddy Mugi and Chandramohan VP. (2023) "Performance assessment of passive indirect solar dryer comparing without and with heat storage unit by investigating the drying kinetics of carrot",Energy Nexus, doi={https://doi.org/10.1016/j. nexus.2023.100178}

DOI: 10.1016/j.nexus.2023.100178

Google Scholar

[28] S. Abubakar, S. Umaru, M.U. Kaisan, U.A. Umar, B. Ashok and K. Nanthagopal (2018) "Development and performance comparison of mixed-mode solar crop dryers with and without thermal storage", Renewable Energy, 128:285-298 doi={https://doi.org/10.1016/j.renene. 2018.05.049}

DOI: 10.1016/j.renene.2018.05.049

Google Scholar

[29] Boonthum, Eakpoom; Sirichana, Sirichai; Namkhet, Aphainun and Teeboonma, Umphisak (2024), "Comparative Study on Performance of Passive and Active Solar Dryer", Key Engineering Materials 978: 97-103, doi={

DOI: 10.4028/p-2gfc9w

Google Scholar