2.1.3. Experimental Procedure

Freshly harvested maize from a local farm was used to evaluate the performance of the dryer. The initial and final moisture contents of the sample was determined using a pre-calibrated John Deere (JD) moisture meter manufactured by AgraTronix™ (Moisture Check Plus™), (SW08120, Moline, IL, USA). Temperature distribution in the dryer was monitored by temperature sensors positioned in the dryer, as shown in Figure 2. From the base of the drying bin, temperature sensors were placed at 15 cm, 30 cm, and 45 cm representing Level 1 (L1), L2, and L3, respectively. At each level (L1, L2, and L3) in the drying chamber, three different sensors were distributed radially at every level. With the use of an anemometer thermo-anemometer (Extech, Melrose, MA, USA) at the suction end of the blower, the airflow rate during the experiment was measured to be 10 m3/s.

**Figure 2.** Longitudinal cross-section showing points of data collection.

In the process of monitoring moisture loss in the drying bin, a sampling rod was used to take maize samples from the inner and outer sections of the drying bin, at each of the drying levels as shown in Figure 3, and 70 g was taken from the sample lot for analyses. Samples were taken at all levels; L1, L2, and L3, at three different points, P1, P2, and P3. Furthermore, samples were taken from both inner and outer sections to check for moisture reduction in maize at every given point. Representative moisture content and temperature data were analyzed based on the average of the data taken at various points at each level.

**Figure 3.** The transversal section of the drying chamber showing sampling points for moisture determination.

#### 2.1.4. Dryer Performance Indices

Dryer performance indices such as drying rate, moisture extraction rate, and drying efficiency were considered for the performance assessment of the crossflow column dryer. Equations (1)–(3) show the expressions that were used to determine the performance indices.

#### Drying Rate, DR

The drying rate, DR, was determined using Equation (1).

$$DR = \frac{M\_{i-}M\_d}{t}.\tag{1}$$

where *Mi* = initial moisture content (% w.b.), *Md* = final moisture content (% w.b.), and *t* = drying time (h).

#### Moisture Extraction Rate, MER

Moisture extraction rate was determined using Equation (2).

$$M\_{ER} = \left(\mathcal{W}\_{\dot{l}} \times \left(\frac{M\_{\dot{l}} - M\_d}{100 - M\_d}\right)\right) / t \tag{2}$$

where *MER* = moisture extraction rate (kg/hr), *Wi* = initial mass of grain dried (kg), *Mi* = initial moisture content (% w.b.) and *Md* = final moisture content (% w.b.) and *t* = drying time (h).
