https://orcid.org/0000-0002-1915-2800
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ABSTRACT
This research study presents the experimental analysis of an indirect mode solar dryer with paraffin wax as a thermal energy storage material for drying wheat seeds. An equal amount of 1000 grams of wheat seeds with an initial moisture content of 20.2% (wb) were put in the lower tray, upper tray of solar dryer, and at the open sun. The recommended moisture content of dried wheat seeds was obtained as 12.8% (wb) in the lower tray in 6 hours of drying, while 13.3% (wb) in the upper tray and 14.4% (wb) in the open sun drying were obtained at the same drying time. The drying rate of the lower tray is 5.38% and 20.34% higher than that of the upper tray and open sun drying after the first hour of drying. The average value of effective moisture diffusivity for the lower tray was 1.05684 × 10−8 m2/s which was 4.31% and 22.93% greater than that for the upper tray and open sun drying, respectively. The average values of collector efficiency and drying efficiency were obtained as 55.25% and 5.42%, respectively with maximum values as 70.76% and 15.83%, respectively. The two-term model shows the best kinetic behavior for drying wheat seeds in indirect mode solar dryer. For quality of dried wheat seeds, total plate count values were obtained which shows that the growth of bacteria and fungus is very much less in wheat seed dried in solar dryer as compared to fresh wheat seeds and dried in open sun drying.
Nomenclature
| Ac | = | Solar collector’s cross-sectional area (m2) |
| x, y, z, n | = | Drying coefficients |
| At | = | Area under solar irradiation (m2) |
| Ap | = | Exposed surface area of product (m2) |
| cpa | = | Sp. heat of air (Joule/kilogramme-Kalvin) |
| Deff | = | Effective moisture diffusivity (m2/s) |
| E | = | Total energy used for drying |
| f | = | Dilution factor |
| I | = | Total solar insolation (W/m2) |
| h, g, p, R | = | Drying constants (/hr) |
| L | = | Latent heat of vaporization (J/kg) |
| m | = | Mass of air (kg) |
| Me | = | Equilibrium moisture content (wb) |
| Mi | = | Initial moisture content (wb) |
| ma | = | Mass flow rate of inlet air (kg/s) |
| ml | = | Mass of water removed (kg) |
| MRexp,i | = | experimental moisture ratio of ith observation |
| MRpre,i | = | predicted moisture ratio of ith observation |
| Mt | = | Moisture content at time “t” (wb) |
| N | = | Number of observations |
| Nc | = | Number of colonies |
| Q | = | Hear transfer (Watt) |
| r | = | Product’s half-thickness (m) |
| t | = | Drying time (hours) |
| Tfi | = | Air inlet temperature (°C) |
| Tfo | = | Air outlet temperature (°C) |
| v | = | Velocity of air (m/s) |
| Vp | = | Volume of culture plate |
| V | = | Volume of product being dried (m3) |
Greek symbols
| η | = | Efficiency (%) |
| ρ | = | Air density (kg/m3) |
Abbreviation
| DR | = | Drying rate |
| IST | = | Indian standard time |
| MR | = | Moisture ratio |
| MC | = | Moisture content |
| TPC | = | Total plate count |
Disclosure statement
No potential conflict of interest was reported by the author(s).
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2022.2118907