Drying kinetics of whole and sliced turmeric rhizomes (Curcuma longa L.) in a solar conduction dryer

Abstract

Available online xxxxKeywords: Conduction Diffusivity Drying Model Moisture Simulation Solar Turmeric A B S T R A C T Drying of turmeric was carried out in a solar conduction dryer (SCD). Drying air temperature was achieved around 39-51°C for an ambient temperature in the range of 25-28°C. Moisture content from 78.65% (wb), was reduced to 6.36% (wb) and 5.50% (wb) for solid and sliced samples respectively in 12 h effective drying time. Drying curve of sliced samples showed more uniform falling in comparison to that of whole samples. The average effective moisture diffusivity was found to be 1.852 · 10 À10 m 2 s À1 for slab samples and 1.456 · 10 À10 m 2 s À1 for solid samples. Out of four models tried for simulation, Page model was found as best fitted thin layer drying model when simulation was done for all the drying data. The overall thermal efficiency of the dryer was found to be 55%. Drying of sliced rhizomes showed better drying kinetics and effective drying time could be reduced by slicing instead of drying in whole form.

Drying Kinetics of Sliced Pineapples in a Solar Conduction Dryer

“…Loading and unloading were done by sliding the trays through the sides of the dryer. The original Solar Conduction Dryer was developed by a group of innovators known as Science for Society (S4S) and fabricated from hollow sections of stainless steel tubes (http://scienceforsociety.co.in/solar-dryer/) and was reported by Borah, Hazarika, and Khayer (2015) to have an efficiency of 55 %. …”

“…This set of experimental runs was carried out with 3-5 mm thickness of pineapple slices by loading all four drying trays at about 75 percent of tray area (Borah et al, 2015) with the remaining fraction of tray area exposed to solar radiation. Two of the drying trays were placed in the Solar Conduction Dryer (SCD) whilst the remaining two were placed on a raised platform by the side of the SCD.…”

“…With this set of experimental runs, the four drying trays were loaded at about 75 percent of their drying area (Borah et al, 2015) with each tray containing one of either 3 mm, 5 mm, 7 mm or 10 mm thickness of sliced pineapples in thin layers. These four thicknesses of sliced pineapples were dried concurrently under the same weather conditions in the four drying chambers of the SCD.…”

“…However the rate at which sample slices loaded at 50 percent drying tray area was dried was considerably faster than those loaded at 75 and 100 percent of drying tray area confirming the significance of the conduction of heat through the trays in the drying process. (Borah et al, 2015) of the actual drying tray area (0.29 m × 0.39 m) resulting in 0.10179 m 2 effective area available for drying. The overall thermal efficiencies for the three loading conditions were then calculated using equation (5).…”

Modeling drying kinetics of yellow potatoes (Solanum gonyocalix)

“…Also, Kaleta and Gornicki (2010) drying apples in cubes & slices in a laboratory type dryer with the initial moisture content ranged from 6.09 to 7.83 kg water/kg dry matter (from 85.9 to 88.7 % w.b). Borah, Hazarika & Khayer (2015) studied tumeric rhyzome samples, which were boiled for two minutes, cutted in slices of cylindrical shape (10-14 mm thickness and 50-70 mm length) and dried in a solar conduction dryer at air temperatures of 39-51 °C. The drying process of the rhizomes showed better kinetics by slicing and the effective drying time could be reduced by slicing the rhizomes instead of drying them as a whole.…”