Design and Testing of a Natural Convection Solar Tunnel Dryer for Mango

Simate, Isaac N.; Cherotich, Sam

doi:10.1155/2017/4525141

Cited by 14 publications

(11 citation statements)

References 21 publications

(27 reference statements)

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“…Pick-up efficiency recorded for both dryers were very low (8.1% and 0.4%) compared to the findings of Isaac and Sam (35%), [15]. This shows that the ability of the heated air in dryers to absorb moisture is underutilized.…”

Section: Resultsmentioning

confidence: 53%

Comparative Studies of Two Developed On-farm Solar Dryers for Vegetables

Okaiyeto¹,

Unguwanrimi²,

Ogijo³

et al. 2020

JERR

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This research work was carried out to provide local farmers with on-farm solar dryers to minimize post-harvest losses of vegetables. Two dryers (Mixed mode and Indirect mode on-farm solar dryers) were constructed using locally available materials. The dryers basically consist of a blower, a collector area and a drying chamber. Aluminum sheet is placed inside the collector which serves as the absorbing material. An electrical axial fan was placed before the air duct to supply air responsible for forcing heated air to blow over the vegetables to be dried. Incorporated in the drying chamber are trays which provide a platform where the products to be dried were spread evenly. Transparent polythene material of 0.2 mm thickness with wooden frame was used as cover for the dryers. The dryers were evaluated to determine drying time and performance efficiencies, using Baobab leaves, Tomato and Okra slices as test crops. Collected data were analyzed using Statistical Analysis Software (SAS). The effects of variation of the independent factors were verified using Analysis of variance (ANOVA) at 1% and 5% levels of significant. Mean separation was carried out on significant factors using Duncan Multiple Range Test (DMRT). The results obtained showed the performance of the developed dryers, which indicates that drying time of mixed mode on-farm solar dryer stood at 56 hrs and 46 hrs while that of the indirect mode dryer was 76.67 hrs and 57 hrs and that of open sun drying was 154 hrs and 127 hrs for tomato and okra slices respectively. Results obtained showed that average system drying, energy collection and pick up efficiencies for the three test crops were 16.35%, 21.1% and 8.05% for mixed mode dryer respectively and 28.63%, 45.3% and 0.3% for indirect mode dryer, respectively. From the results obtained the mixed mode dryer dried all the products faster while indirect mode has superior energy efficiencies.

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Section: Resultsmentioning

confidence: 53%

Comparative Studies of Two Developed On-farm Solar Dryers for Vegetables

Okaiyeto¹,

Unguwanrimi²,

Ogijo³

et al. 2020

JERR

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“…The chimney unit was perpendicular to the drying unit. The STD is described in detail by (Cherotich and Simate, 2016) and (Simate and Cherotich, 2017). As seen from Figure 1, a multi-channel data logger (Campbell Scientific, Model CR1000) was connected to the STD to record air temperatures, relative humidity and solar radiation during the drying period.…”

Section: Energy and Environment Researchmentioning

confidence: 99%

“…Classification of solar dryers is through the solar energy collection method and transferring it to the product as indirect, direct and mixed-type. Solar dryers however require vigilant design and experimentation to determine the drying time, solar radiation, and attainable air conditions (temperature, relative humidity and airspeed) for uniformity when drying so that a high quality product is obtained (Simate and Cherotich, 2017). Solar dryers can be cost effective because relatively unskilled village artisans can construct, operate and maintain the dryers at minimum cost and cheap and locally available materials can be used for the construction (Simate, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Solar dryers can be cost effective because relatively unskilled village artisans can construct, operate and maintain the dryers at minimum cost and cheap and locally available materials can be used for the construction (Simate, 2003). The natural convection solar tunnel fruit dryer ( Figure 2) used in this study was fabricated from locally available materials by Simate and Cherotich, (2017) which was used to develop an appropriate thin layer drying model for mango. Thin layer drying equations are utilized for the estimation of drying times of several products and also to generalize drying curves (Sahari and Driscoll, 2013).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thin Layer Drying and Modelling of Poultry Litter Briquettes

Molefe¹,

Simate²

2019

EER

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Drying is an energy consuming process influenced by humidity, air velocity and temperature and is defined as a heat conveyance process wherein the product is heated hence removing moisture. Thin layer drying equations are used to estimate drying times of products and generalizing their drying curves. In this study, mathematical modelling and prediction of drying behavior of poultry litter briquettes (PLB) was investigated through open sun drying (OSD) and solar tunnel drying for moisture content (MC) calculations. A solar tunnel dryer (STD) having a: black painted collector unit, drying unit and black painted vertical bare flat-plate chimney was used. MC results were converted to moisture ratio and fitted into 12 different thin layer drying models, using Microsoft Office Excel, which were compared according to their coefficients of determination to estimate drying curves of PLB. The most accurate model was selected based on three statistical parameters: correlation coefficient (R2), chi-squared (χ2) and Root Mean Square Error (RMSE). Solar insolation of between 220 and 1005 W/m2 resulted in air temperature of up to 64oC at the collector unit, up to 60oC at the drying unit and an ambient temperature of up to 31oC. Exposure of PLB with an average initial MC of 61% (w.b.) to these conditions resulted in a final MC in a range of 0.2-11.2% (w.b.) in 31-55 hours. PLB was dried to similar final weight from whichever drying method although OSD took longer than STD. The Logarithmic model was found to satisfactorily describe the drying curves of PLB with R2 of 9.93E-01-9.99E-01; χ2 of 1.36E-11-6.50E-14; and RMSE of 2.94E-02-1.30E-02.

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“…Solar dryers can be classified according to the method of heat transfer to the drying material as indirect through convection of hot air from a solar air heater to the material (Boulemtafes-Boukadoum & Benzaoui, 2011), direct through solar radiation on to the material (Simate & Ahrné, 2006), mixed-mode through a combination of direct radiation and hot air to the material (Simate, 1999), or through a combination of direct radiation and conduction of heat from a solid tray where the drying material is placed (Daud & Simate, 2017). Solar dryers can further be classified in terms of air flow as natural (free) convection (Berinyuy, Tangka & Weka Fotso, 2012;Adelaja & Babatope, 2013;Panwar, Kaushik & Kothari, 2016;Simate & Cherotich, 2017) or forced convection (Bennamoun, 2012). Despite the difficulties in quantitative understanding of the drying processes, such as non-linear physical processes and material transport properties that are highly dependent on moisture content and temperature, exergy analysis is effective in providing optimal solutions to drying problems (Dincer & Rosen, 2007).…”

Section: Introductionmentioning

confidence: 99%

Energy and Exergy Analysis of an Indirect-Mode Natural Convection Solar Dryer for Maize

Simate¹

2021

EER

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The energy and exergy analysis of an indirect-mode natural convection solar dryer for maize grain is presented. Two different sizes of maize grain bed depths of 0.04 m and 0.02 m translating into grain loads of 10 kg and 5 kg respectively, are used in the study to determine their effects on the collector energy and exergy efficiencies and the drying chamber exergy efficiency. Experiments were carried out using an indirect-mode laboratory solar dryer under a solar simulator with a radiation setting of 634.78 W/m2. The analysis gave average collector energy efficiencies of 33.3 % and 46.2 % for the 10 kg and 5 kg loads, respectively, which are higher than the collector exergy efficiencies of 2.4 % and 2.6 % for the 10 kg and 5 kg loads, respectively. The drying chamber exergy efficiencies are 45.2 % and 28.4 % for the 10 kg and 5 kg loads, respectively. In view of this, the 5 kg load is considered to be more efficient at extracting energy from the collector due to higher air flow resulting from its relatively thin grain bed depth of 0.02 m, but less efficient in utilising the extracted energy to evaporate moisture from the grain which has resulted in a lower drying chamber exergy efficiency. Further, the exergy loss in the drying chamber for the 5 kg load is higher than that in the 10 kg load as 72.3 % of the exergy entering the drying chamber is lost through emissions as well as destroyed through internal irreversibility compared to 57.0 % for the 10 kg load. 

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Design and Testing of a Natural Convection Solar Tunnel Dryer for Mango

Cited by 14 publications

References 21 publications

Comparative Studies of Two Developed On-farm Solar Dryers for Vegetables

Comparative Studies of Two Developed On-farm Solar Dryers for Vegetables

Thin Layer Drying and Modelling of Poultry Litter Briquettes

Energy and Exergy Analysis of an Indirect-Mode Natural Convection Solar Dryer for Maize

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