Experimental Study of a Mixed Solar Dryer: Application to Drying Okra

Dianda Boureima; Ouédraogo Germain Wende Pouiré; Aoué Safiatou; Kam Sié; Bathiébo Dieudonné Joseph

doi:doi:10.11648/j.sr.20251305.11

Research Article |

| Peer-Reviewed

Experimental Study of a Mixed Solar Dryer: Application to Drying Okra

Dianda Boureima^*

, Ouédraogo Germain Wende Pouiré

, Aoué Safiatou

, Kam Sié

, Bathiébo Dieudonné Joseph

Published in Science Research (Volume 13, Issue 5)

Received: 16 July 2025 Accepted: 20 August 2025 Published: 11 September 2025

Views: Downloads:

Download PDF

Share This Article

Twitter
Linked In
Facebook

Abstract

Large-scale agricultural production generally occurs during specific periods of the year. This results in the unavailability of products outside of their production periods. Due to their high water content, most agri-food products deteriorate very quickly under the effect of heat, hence the need to develop preservation techniques. Preservation techniques for fresh produce require energy. Burkina Faso is a country with strong solar potential, which is why solar dryers are the most developed technologies for preserving agri-food products. However, the quality of the dried product depends on the quality of the dryer. Our work focuses on the construction of a mixed solar dryer for drying agricultural products. The flat-plate collector is equipped with baffles that allow for greater heat exchange between the air and the hot parts (absorber and baffles) of the collector. The drying chamber is fitted with double-sloped glazing on the roof. An experimental study of hygrothermal parameters, such as air temperature at the racks, product temperature, product water content, and relative humidity inside the drying chamber, was conducted to determine the dryer's performance. We also determined the effective diffusion coefficient and efficiency. The evolution of solar irradiation was monitored during drying operations. Experiments show that the temperature inside the dryer can reach 80°C to 100°C. The effective diffusion coefficient is approximately 1.89.10^-7 m²/s, and the dryer's efficiency is 28.56%.

Published in	Science Research (Volume 13, Issue 5)
DOI	10.11648/j.sr.20251305.11
Page(s)	128-135
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Mixed Solar Dryer, Okra, Drying Kinetics, Temperature, Efficiency

1. Introduction

Burkina Faso is a country with a pre-Sahelian climate, with a rainy season lasting approximately four months and a dry season lasting eight months. Agricultural production, being generally seasonal, influences its availability and cost during the dry season. Thus, the preservation of products with high moisture content is a problem that must be resolved to make these products available during the dry season. Open-air drying has been a preservation method for years, but it has drawbacks in terms of the quality of the dried product and a relatively long drying time (a few days). This problem can be addressed by proposing a solar dryer that uses solar radiation to generate the energy needed for drying. Thanks to the strong sunshine our country enjoys, solar dryers have been developed. These dryers are of several types and are classified according to the way in which solar radiation reaches the product. In the literature, several authors, such as Diemuodeke E et al., Eke Ben et al., Atul Sharma et al., Bayopo S et al. and Tefera A et al, have carried out studies on the performance of different forms of solar dryers where the products are exposed to solar radiation

[1-5]

. The results show that they have quite poor performance. Other authors such as Dianda Boureima et al., Thierry Sikoudouin et al., Esakkimuthu et al., V. Shanmugam et al., S. Shanmugam et al., and P. N. Sarsavadia et al., have presented studies on indirect solar dryers where the products are not directly exposed to radiation

[6-11]

. However, indirect dryers have reduced performance on days of low sunshine. To increase solar irradiation on the dryers, researchers have combined the indirect dryer with the direct dryer. Researchers have developed and conducted studies on several types of indirect dryers. F. K. Forson et al. developed a satisfactory numerical model to predict the performance of a mixed solar dryer

[12]

. Bukola O. Bolaji et al. In their study, they obtained a drying speed and collector efficiency of 0.62 kg/h and 57.5% respectively

[13]

. López-Vidaña Erick César et al., developed and evaluated a mixed passive solar dryer. The efficiency of the dryer is estimated at approximately 10.66%

[14]

. Ahmed Djebli et al., presented the results of an experimental and thermodynamic study of tomato drying in a mixed dryer. Gibbs free energy values indicate that solar drying of tomatoes is a spontaneous natural process

[15]

Ikechukwu Celestine Ugwuoke et al. developed and tested a mixed solar dryer for drying several agri-food products. They found that the dryer allowed rapid drying of their products

[16]

. Chandrakumar B Pardhi et al., after developing a mixed solar dryer, carried out tests on it. The results show that the drying rate, collector efficiency and percentage of moisture removed (on a dry basis) for grape drying were 0.38 kg/h, 67.5% and 85.4% respectively

[17]

. All these studies have shown the interest of mixed solar dryers. In most of these works, the part exposed to the sun is on a single slope.

Our work consists of carrying out and experimentally studying the performance of a mixed dryer whose direct sun exposure surface is double slope and the flat collector equipped with baffles. The work consisted of determining the temperatures of the different parts of the dryer, determining the drying kinetics of dried okra in the dryer, evaluating the diffusion coefficient of water in the product and the yield.

2. Materials and Methods

2.1. Materials

2.1.1. The Flat-plate

It consists of a 2 mm thick galvanized sheet metal absorber painted matte black, topped with rectangular obstacles (baffles). The entire assembly is covered with a 5 mm thick clear glass pane. The side and bottom surfaces are thermally insulated with polystyrene. Air circulates between the glass and the absorber to be heated and then flows into the drying chamber. The collector is inclined at an angle of 15° to the horizontal plane and permanently oriented towards the south.

Download: Download full-size image

Figure 1. flat panel sensor (equipped with baffle).

2.1.2. The Drying Chamber

The drying chamber is a trapezoidal box. The walls are made of aluminum-zinc sheet metal and insulated with polystyrene and then redwood plywood. The entire structure is clad in aluminum-zinc sheet metal to resist humidity. The upper part is glazed to allow sunlight to penetrate the chamber. The entire structure is topped with a chimney that facilitates the evacuation of humid drying air. The drying chamber contains four galvanized wire racks where the products to be dried are displayed. The racks are numbered from bottom to top, from 1 to 4.

Download: Download full-size image

Figure 2. Schematic of the drying chamber.

2.1.3. The Mixed Solar Dryer

The two units, namely the baffle plate collector and the drying cage, are connected to form the combined solar dryer.

Download: Download full-size image

Figure 3. Mixed solar dryer.

2.1.4. Measuring Devices

The various temperatures were measured using K-type thermocouples connected to a GRAPHTEC Midi LOGGER GL 220 data logger. The data logger has a measurement error of ±0.05% of the measured value and is used for temperatures ranging from -100°C to 1370°C.

Solar irradiation was measured using a solarimeter. It has a sensitivity of 72 mV/1000 W.m^-2. A hygrometer was used to measure the relative humidity (RH) in the drying chamber. This device has a measurement range of 0 to 100% humidity with a resolution of 0.1% RH and a measurement error of ±3% for a range of 20% to 80% and ±5% for values below 20% RH and above 80% RH.

Download: Download full-size image

Figure 4. Measuring devices (a: GL220 datalogger, b: thermocouples, c: solarimeter, d: hygrometer).

2.2. Methods

2.2.1. Experimental Protocol

The fresh okra used for drying was washed, drained, and cut into cylindrical shapes. It was then weighed and placed on the drying racks. The sensor and drying chamber were first cleaned.

Thermocouples were placed in the drying chamber (at the inlet, on the racks, and on the products) and in the ambient air. A hygrometer was placed in the drying chamber to monitor the relative humidity of the drying air. A solarimeter recorded the solar irradiation reaching the site. The okra was regularly weighed until a nearly constant mass was obtained, at which point drying was stopped.

2.2.2. Theoretical Approach

The water content at each time was determined by equation (1):

X (t) = \frac{m (t) - m_{s}}{m_{s}}

(1)

With:

X (t) :

the water content at time t;

m (t) :

the mass at time t;

m_{s} :

dry mass

The overall efficiency of the dryer is calculated from equation (2):

(2)

With:

M_v: mass of water evaporated during the total drying time in kg;

L_v: latent heat of vaporization in J/kg;

G_n: average daily solar radiation on the dryer surface in W/m²;

A: area of the absorber exposed to solar radiation in m²;

t_s: drying time in s.

The diffusion coefficient Deff (m².s^-1) is determined by equation (3):

(3)

With:

X*: reduced water content;

r: product radius (m);

α₀: Bessel function of order 0;

t: time (s);

D_eff: diffusion coefficient (m².s^-1)

3. Results

We conducted trials of the okra drying process using our mixed solar dryer to determine its performance. The trials were conducted during September 2023, and the results are presented as follows.

3.1. Irradiation Solaire

Download: Download full-size image

Figure 5. Evolution of solar irradiation.

Observation of the solar irradiation curve reveals a general bell-shaped trend. However, fluctuations are notable, mainly due to cloudy periods, resulting in sudden drops in sunshine. These observations highlight the impact of variable weather conditions. The maximum solar irradiation is recorded at around 12h22min and is worth 1018 W/m². This value indicates a very sunny day.

3.2. Relative Humidity of the Air

Download: Download full-size image

Figure 6. Relative humidity and temperature of drying air.

It can be seen that during the two days of drying, the relative humidity has an opposite evolution to that of the temperature. In other words, when the air temperature in the rack room increases, the relative humidity decreases, and vice versa. The maximum values reached by the air are approximately 60°C and 70°C. These maximum temperature values correspond to minimum values of relative humidity which are approximately 35% and 20%. The increase in temperature promotes the evaporation of the moisture present in the air and vice versa. The air thus becomes capable of containing a greater quantity of water vapor, in this case that of the products to be dried. On the other hand, when the temperature inside the room decreases, this reduces the capacity of the air to contain water vapor, which leads to an increase in the relative humidity of the air inside the rack room. A previous study in another indirect solar dryer gives a similar result

[18]

3.3. Product and Drying Air Temperatures

Figures 7 and 8 show the changes in the temperatures of the drying air around racks 1 and 4 as well as the temperatures of the products placed on these racks.

Download: Download full-size image

Figure 7. Changes in the temperatures of the drying air and the product on the rack1.

Download: Download full-size image

Figure 8. Changes in the temperatures of the drying air and the product on rack 4.

These curves represent the values measured during the two drying days. We first note that the drying air temperatures around rack 4 are higher than those around rack 1. This is explained by the fact that rack 4 is located under the greenhouse placed above the dryer. The air temperatures around rack 1 and rack 4 reached maximum values of 60°C and 80°C respectively on the first day and maximum values of 70°C and 100°C on the second day. These high temperatures are directly influenced by the good sunshine on these days. In each of these figures, we see a change in the product temperature similar to that of the drying air temperature. The product temperature increases with that of the drying air and tends towards the latter. This is explained by the fact that hot air serves to evaporate the water from the product and at the same time increase the temperature of the product. Such a result has also been presented in the literature

[19, 20]

3.4. Drying Kinetics

Download: Download full-size image

Figure 9. Okra drying kinetics.

Figure 9 shows that the drying of the products placed on rack 4 is a little faster compared to that of rack 1. This is explained by the high temperature of the drying air around rack 4. We also observe overall a single drying phase, namely the decay phase. There is first a rapid decrease until the end of the first day of drying (15: 46), then a slow decrease for the rest of the drying. At the beginning of the process, when the okra is still relatively wet, the moisture is more concentrated on the surface of the products, which promotes rapid evaporation. However, as drying progresses and the amount of moisture on the surface of the products decreases, evaporation becomes increasingly slow. The majority of authors in the literature reach the same result for agri-food products

[18, 21-25]

. The drying time was 11 hours.

3.5. Effective Diffusion Coefficient of Okra

The representation ln(X*) =f(t) allows us to obtain a straight line, and from this line we deduce the effective diffusion coefficient. Its determined value is 1.89.10-7 m²/s.

This value is higher than those obtained by some authors during okra drying

[23, 25-28]

. This could be due to the high temperature of the drying air.

3.6. Efficiency

The efficiency of the dryer calculated using equation (3) is 28.56%. This means that 28.56% of the incident solar energy is used for drying the products through our mixed solar dryer. Lakshmi et al obtained an efficiency of 12% with their mixed solar dryer

[29]

. López-Vidaña Erick César et al, obtained an efficiency of 10.66%

[14]

. Arslan Afzal et al., in their study concluded that their dryer has an efficiency of 33%

[24]

. Considering the efficiencies in the literature we can say that our dryer has a good efficiency.

4. Conclusion

The study of the mixed solar dryer with a double-sloped glass top showed very high temperatures in the drying cage. These temperatures can allow the drying of other products requiring sufficient heat. The temperature of the okra subjected to drying reaches temperatures of approximately 80°C with an effective diffusion coefficient of 1.89.10-7 m²/s. The estimated efficiency is 28.56%. However, regulation of the drying air temperature is necessary for some products whose drying temperatures are of the order of 50°C or less.

Abbreviations

$X (t)$	Water Content at Time t(s)
$m (t)$	Mass at Time t(s)
$m_{s}$	Dry Mass (kg)
$η_{s}$	Overall Efficiency of the Dryer
M_v	Mass of Water Evaporated During the Total Drying Time (kg)
L_v	Latent Heat of Vaporization in (j/kg)
G_n	Average Daily Solar Radiation on the Dryer Surface (w/m²)
A	Area of the Absorber Exposed to solar Radiation (m²)
t_s	Drying Time (s)
Deff	Diffusion Coefficient (m².s^-1)
X*	Reduced Water Content
r	Product Radius (m)
α₀	Bessel Function of Order 0
t	Time (s)

Author Contributions

Dianda Boureima: Conceptualization, Validation

Ouédraogo Germain Wende Pouiré: Methodology

Aoué Safiatou: Data curation, Funding acquisition

Kam Sié: Validation

Bathiébo Dieudonné Joseph: Validation

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Diemuodeke E. OGHENERUONA, Momoh O. L. YUSUF. Design and Fabrication of a direct natural convection solar dryer for tapioca”, Leonardo Electronic Journal of Practices and Technologies, 2011, (18).
[2]	Eke, Ben Akachukwu. Development of small scale direct mode natural convection solar dryer for tomato, okra and carrot, International Journal of Engineering and Technology, 2013, 3 (2).
[3]	Atul Sharma, C. R. Chen, Nguyen Vu Lan. Solar-energy drying systems: A review”, Renewable and Sustainable Energy Reviews, 2009, (13), https://doi.org/10.1016/j.rser.2008.08.015
[4]	Bayopo, S. O. and Alonge, O. I. Development and Quality Analysis of a direct solar dryer for fish. Food and Nutrition Sciences, 2018, (9), https://doi.org/10.4236/fns.2018.95037
[5]	Tefera A, Endalew W and Fikiru B. Evaluation and demonstration of direct solar potato dryer. Livestock Research for Rural Development, 2013, 25(12).
[6]	DIANDA Boureima, OUEDRAOGO Emmanuel, BADO Nébon, TRAORE Abdoul Fataho, NANA Gilbert, KY S. M Thierry, BATHIEBO Dieudonné Joseph. Numerical study of papaya drying in a solar dryer, JCBPS; Section C;), 2024, 14(3), https://doi.org/10.24214/jcbps.C.14.3.21223
[7]	Thierry Sikoudouin Maurice KY, Damus Abdoul Aziz Traoré, Bienvenu Magloire Pakouzou, Boureima Dianda, Emmanuel Ouedraogo et Dieudonné Joseph Bathiébo. Expermiental study of an indirect solar dryer using a new collector system: Application to Mango and Ginger Drying, Contemporary Engenering science, 2021, 14(1). https://doi.org/10.12988/ces.2021.91680
[8]	S. Esakkimuthu, Abdel Hakim Hassabou, C. Palaniappan, Markus Spinnler, Jurgen Blumenberg, R. Velraj. Experimental investigation on phase change material based thermal storage system for solar air heating applications. Solar Energy, 2013, (88). https://doi.org/10.1016/j.solener.2012.11.006
[9]	V. Shanmugam, E. Natarajan. Experimental study of regenerative desiccant integrated solar dryer with and without reflective mirror. Applied Thermal Engineering, 2007, 27(8-9). https://doi.org/10.1016/j.applthermaleng.2006.09.018
[10]	S. Shanmugam, P. Kumar AR., Veerappan. Modeling and Experimental Studies on Oscillating Inclined-Bed Solar Dryer. Journal of Solar Energy Engineering, 2013, (135). https://doi.org/10.1115/1.4023592
[11]	P. N. Sarsavadia. Development of a solarassisted dryer and evaluation of energy requirement for the drying of onion. Renewable Energy, 2007, (32). https://doi.org/10.1016/j.renene.2006.12.019
[12]	F. K. Forson, M. A. A. Nazha, H. Rajakaruna. Modelling and experimental studies on a mixed-mode natural convection solar crop-dryer, Solar Energy, 2007, (81). https://doi.org/10.1016/j.solener.2006.07.002
[13]	Bukola O. Bolaji and Ayoola P. Olalusi, Performance Evaluation of a Mixed-Mode Solar Dryer, AU J. T. 2008, 11(4).
[14]	López-Vidaña Erick César, César-Munguía Ana Lilia, García-Valladares Octavio, Pilatowsky Figueroa Isaac, Brito Orosco Rogelio. Thermal performance of a passive, mixed-type solar dryer for tomato slices (Solanum lycopersicum), Renewable Energy, 2019, https://doi.org/10.1016/j.renene.2019.09.018
[15]	Ahmed Djeblia, Salah Haninia, Ouassila Badaouia, Mouloud Boumahdia, A new approach to the thermodynamics study of drying tomatoes in mixed solar dryer, Solar Energy, 2019,(193). https://doi.org/10.1016/j.solener.2019.09.057
[16]	Ikechukwu Celestine Ugwuoke, Ibukun Blessing Ikechukwu, Ogbe Eric Ifianyi. Design and Development of a Mixed-Mode Domestic Solar Dryer, I. J. Engineering and Manufacturing, 2019, (3). https://doi.org/10.5815/ijem.2019.03.05
[17]	Chandrakumar B Pardhi and Jiwanlal L Bhagoria. Development and performance evaluation of mixed-mode solar dryer with forced convection, International Journal of Energy and Environmental Engineering, 2013, (4). https://doi.org/10.1186/2251-6832-4-23
[18]	Dianda Boureima, Traore Abdoul Fataho, Ouedraogo Adama, KY Sikoudouin Maurice Thierry, Ouedraogo Issaka a, Kam Sié and Bathiébo Dieudonné. Experimental Study of Papaya Drying in an Indirect Solar Dryer in Natural Convection, Current Journal of Applied Science and Technology, 2022, 41(32). https://doi.org/10.9734/cjast/2022/v41i3231817
[19]	Ramadan El Gamal, Frederik Ronsse, Jan G. Pieters. Modeling Deep-Bed Grain Drying Using COMSOL Multiphysics, excerptfrom the proceedings of the comsol conference in Rotterdam, 2013
[20]	DIANDA Boureima, KY Thierry S. M., COMPAORE Abdoulaye, GUENGANE Hassim, OUEDRAOGO Salifou and BATHIEBO D. Joseph. Modeling of tomato convective drying with comsol software, Asian Journal of Science and Technology, 2019, 10(8).
[21]	Boureima Dianda, Labayè Yves Japhet Koussoubé, Lareba Adélaïde Ouédraogo, Moctar Ousmane and Dieudonné Joseph Bathiébo. Realization and Experimental Study of a Forced Convection Solar Dryer, Asian Journal of Physical and Chemical Sciences, 2024, 12(2). https://doi.org/10.9734/ajopacs/2024/v12i2222
[22]	Dianda B, Ousmane M., Kam S., Ky T. and Bathiébo D. J. Experimental study of the kinetics and shrinkage ofntomato slices in convective drying, African journal of food science, 2015, 9(5). https://doi.org/10.5897/AJFS2015.1298
[23]	T. J. Afolabi, Thin Layer Drying Kinetics and Modelling of Okra (Abelmoschus Esculentus (L.) Moench) Slices under Natural and Forced Convective Air Drying, Food Science and Quality Management, 2014, (28).
[24]	Arslan Afzal, Tahir Iqbal, Kamran Ikram, Muhammad Naveed Anjum, Muhammad Umair, Muhammad Azam, Sajeela Akram, Fiaz Hussain, Muhammad Ameen ul Zaman, Abid Ali, Faizan Majeed. Development of a hybrid mixed-mode solar dryer for product drying, Heliyon, 2003, (9) e14144. https://doi.org/10.1016/j.heliyon.2023.e14144
[25]	Kritsna Mongkolkerd and Siva Achariyaviriya. Effective diffusion coefficient of okra during hot air drying, Interdisciplinary Research and Development in ASEAN Universities, 2013, 2(1).
[26]	Ouoba Kondia Honoré, Zougmoré François, Sam Raguilignaba, Toguyeni Aboubacar, Desmorieux Hélène. Characterization of okra convective drying, influence of maturity. Food and Nutrition Sciences, Food and Nutrition Sciences, 2014, (5). https://doi.org/10.4236/fns.2014.56069
[27]	Germain Wende Pouiré Ouedraogo, Boureima Kaboré, Sié Kam, Dieudonné Joseph Bathiébo. Determination of Physical and Chemical Properties of Okra During Convective Solar Drying. International Journal of Engineering and Advanced Technology, 2007, 7(1).
[28]	Go¨kc¸e Dadalı, Dilek Kılıc¸ Apar, and Belma O ¨ zbek. Estimation of Effective Moisture Diffusivity of Okra for Microwave Drying, Drying Technology, 2007, (25). https://doi.org/10.1080/07373930701536767
[29]	Lakshmi DVN, Muthukumar P, Layek A, Nayak PK. Drying kinetics and quality analysis of black turmeric (Curcuma caesia) drying in a mixed mode forced convection solar dryer integrated with thermal energy storage, Renewable Energy, 2018. https://doi.org/10.1016/j.renene.2017.12.053

Cite This Article

Plain Text BibTeX RIS

APA Style

Boureima, D., Pouiré, O. G. W., Safiatou, A., Sié, K., Joseph, B. D. (2025). Experimental Study of a Mixed Solar Dryer: Application to Drying Okra. Science Research, 13(5), 128-135. https://doi.org/10.11648/j.sr.20251305.11

Copy | Download

ACS Style

Boureima, D.; Pouiré, O. G. W.; Safiatou, A.; Sié, K.; Joseph, B. D. Experimental Study of a Mixed Solar Dryer: Application to Drying Okra. Sci. Res. 2025, 13(5), 128-135. doi: 10.11648/j.sr.20251305.11

Copy | Download

AMA Style

Boureima D, Pouiré OGW, Safiatou A, Sié K, Joseph BD. Experimental Study of a Mixed Solar Dryer: Application to Drying Okra. Sci Res. 2025;13(5):128-135. doi: 10.11648/j.sr.20251305.11

Copy | Download

@article{10.11648/j.sr.20251305.11,
  author = {Dianda Boureima and Ouédraogo Germain Wende Pouiré and Aoué Safiatou and Kam Sié and Bathiébo Dieudonné Joseph},
  title = {Experimental Study of a Mixed Solar Dryer: Application to Drying Okra
},
  journal = {Science Research},
  volume = {13},
  number = {5},
  pages = {128-135},
  doi = {10.11648/j.sr.20251305.11},
  url = {https://doi.org/10.11648/j.sr.20251305.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sr.20251305.11},
  abstract = {Large-scale agricultural production generally occurs during specific periods of the year. This results in the unavailability of products outside of their production periods. Due to their high water content, most agri-food products deteriorate very quickly under the effect of heat, hence the need to develop preservation techniques. Preservation techniques for fresh produce require energy. Burkina Faso is a country with strong solar potential, which is why solar dryers are the most developed technologies for preserving agri-food products. However, the quality of the dried product depends on the quality of the dryer. Our work focuses on the construction of a mixed solar dryer for drying agricultural products. The flat-plate collector is equipped with baffles that allow for greater heat exchange between the air and the hot parts (absorber and baffles) of the collector. The drying chamber is fitted with double-sloped glazing on the roof. An experimental study of hygrothermal parameters, such as air temperature at the racks, product temperature, product water content, and relative humidity inside the drying chamber, was conducted to determine the dryer's performance. We also determined the effective diffusion coefficient and efficiency. The evolution of solar irradiation was monitored during drying operations. Experiments show that the temperature inside the dryer can reach 80°C to 100°C. The effective diffusion coefficient is approximately 1.89.10-7 m2/s, and the dryer's efficiency is 28.56%.
},
 year = {2025}
}

Copy | Download

TY - JOUR
T1 - Experimental Study of a Mixed Solar Dryer: Application to Drying Okra

AU - Dianda Boureima
AU - Ouédraogo Germain Wende Pouiré
AU - Aoué Safiatou
AU - Kam Sié
AU - Bathiébo Dieudonné Joseph
Y1 - 2025/09/11
PY - 2025
N1 - https://doi.org/10.11648/j.sr.20251305.11
DO - 10.11648/j.sr.20251305.11
T2 - Science Research
JF - Science Research
JO - Science Research
SP - 128
EP - 135
PB - Science Publishing Group
SN - 2329-0927
UR - https://doi.org/10.11648/j.sr.20251305.11
AB - Large-scale agricultural production generally occurs during specific periods of the year. This results in the unavailability of products outside of their production periods. Due to their high water content, most agri-food products deteriorate very quickly under the effect of heat, hence the need to develop preservation techniques. Preservation techniques for fresh produce require energy. Burkina Faso is a country with strong solar potential, which is why solar dryers are the most developed technologies for preserving agri-food products. However, the quality of the dried product depends on the quality of the dryer. Our work focuses on the construction of a mixed solar dryer for drying agricultural products. The flat-plate collector is equipped with baffles that allow for greater heat exchange between the air and the hot parts (absorber and baffles) of the collector. The drying chamber is fitted with double-sloped glazing on the roof. An experimental study of hygrothermal parameters, such as air temperature at the racks, product temperature, product water content, and relative humidity inside the drying chamber, was conducted to determine the dryer's performance. We also determined the effective diffusion coefficient and efficiency. The evolution of solar irradiation was monitored during drying operations. Experiments show that the temperature inside the dryer can reach 80°C to 100°C. The effective diffusion coefficient is approximately 1.89.10-7 m2/s, and the dryer's efficiency is 28.56%.

VL - 13
IS - 5
ER -

Copy | Download

Author Information

Dianda Boureima

Institute for Research in Applied Sciences and Technologies, National Center for Scientific and Technological Research, Ouagadougou, Burkina Faso

Contact Email

http://orcid.org/0009-0007-5135-0368
Ouédraogo Germain Wende Pouiré

Higher School of Engineering (HSE), Yembila Abdoulaye TOGUYENI University, Fada N’Gourma, Burkina Faso

Contact Email

http://orcid.org/0009-0003-9307-5625
Aoué Safiatou

Renewable Thermal Energy Laboratory, University Joseph KI-ZERBO, Ouagadougou, Burkina Faso

Contact Email

http://orcid.org/0009-0009-2084-9208
Kam Sié

Renewable Thermal Energy Laboratory, University Joseph KI-ZERBO, Ouagadougou, Burkina Faso

Contact Email

http://orcid.org/0000-0001-7156-7301
Bathiébo Dieudonné Joseph

Renewable Thermal Energy Laboratory, University Joseph KI-ZERBO, Ouagadougou, Burkina Faso

Contact Email

http://orcid.org/0000-0002-5060-6719

Download PDF

Submit an Article

Plain Text BibTeX RIS

APA Style

Boureima, D., Pouiré, O. G. W., Safiatou, A., Sié, K., Joseph, B. D. (2025). Experimental Study of a Mixed Solar Dryer: Application to Drying Okra. Science Research, 13(5), 128-135. https://doi.org/10.11648/j.sr.20251305.11

Copy | Download

ACS Style

Boureima, D.; Pouiré, O. G. W.; Safiatou, A.; Sié, K.; Joseph, B. D. Experimental Study of a Mixed Solar Dryer: Application to Drying Okra. Sci. Res. 2025, 13(5), 128-135. doi: 10.11648/j.sr.20251305.11

Copy | Download

AMA Style

Boureima D, Pouiré OGW, Safiatou A, Sié K, Joseph BD. Experimental Study of a Mixed Solar Dryer: Application to Drying Okra. Sci Res. 2025;13(5):128-135. doi: 10.11648/j.sr.20251305.11

Copy | Download

@article{10.11648/j.sr.20251305.11,
  author = {Dianda Boureima and Ouédraogo Germain Wende Pouiré and Aoué Safiatou and Kam Sié and Bathiébo Dieudonné Joseph},
  title = {Experimental Study of a Mixed Solar Dryer: Application to Drying Okra
},
  journal = {Science Research},
  volume = {13},
  number = {5},
  pages = {128-135},
  doi = {10.11648/j.sr.20251305.11},
  url = {https://doi.org/10.11648/j.sr.20251305.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sr.20251305.11},
  abstract = {Large-scale agricultural production generally occurs during specific periods of the year. This results in the unavailability of products outside of their production periods. Due to their high water content, most agri-food products deteriorate very quickly under the effect of heat, hence the need to develop preservation techniques. Preservation techniques for fresh produce require energy. Burkina Faso is a country with strong solar potential, which is why solar dryers are the most developed technologies for preserving agri-food products. However, the quality of the dried product depends on the quality of the dryer. Our work focuses on the construction of a mixed solar dryer for drying agricultural products. The flat-plate collector is equipped with baffles that allow for greater heat exchange between the air and the hot parts (absorber and baffles) of the collector. The drying chamber is fitted with double-sloped glazing on the roof. An experimental study of hygrothermal parameters, such as air temperature at the racks, product temperature, product water content, and relative humidity inside the drying chamber, was conducted to determine the dryer's performance. We also determined the effective diffusion coefficient and efficiency. The evolution of solar irradiation was monitored during drying operations. Experiments show that the temperature inside the dryer can reach 80°C to 100°C. The effective diffusion coefficient is approximately 1.89.10-7 m2/s, and the dryer's efficiency is 28.56%.
},
 year = {2025}
}

Copy | Download

TY - JOUR
T1 - Experimental Study of a Mixed Solar Dryer: Application to Drying Okra

VL - 13
IS - 5
ER -

Copy | Download