Energy and exergy analyses of okra drying process in a forced convection cabinet dryer

Abstract

A forced convection automatic cabinet dryer integrated with a data logger was designed and fabricated. The okra samples were dried in the dryer at drying temperatures of 50, 60, and 70 °C and at three different load densities of 200, 300, and 400 g at a continuous air velocity of 0.7 m·s<sup>–1</sup>. Energy and exergy analyses of the drying process were performed. The obtained results showed that the energy efficiency, energy utilisation, and utilisation ratio increased from 26.59 to 68.24%, 5.47 to 114.36 W, and 0.36 to 0.71 as the temperature increased to 70 °C, respectively. The inflow, outflow, and exergy losses were in the range of 7.02 to 26.14 W, 4.43 to 14.16 W, and 2.59 to 11.98 W, respectively, while exergy efficiency varied from 49.15 to 63.47%. The findings show that exergy efficiencies decrease with an increase in the drying temperature, but increase with a lower load rate. The index of sustainability varies from 2.14 to 2.77, the value increases as the load density decreases while it decreases with a temperature increment.

Exergy and Energy Analyses of Microwave Dryer for Cantaloupe Slice and Prediction of Thermodynamic Parameters Using ANN and ANFIS Algorithms

“…Table 5 presents the mean exergetic sustainability index and varied from 1.12 to 1.63. Similar reports were reported by Okunola et al [54], Arslan and Aktas [37], and Beigi et al [40] for the exergetic sustainability index range for the drying of okra at 2.14 to 2.77, 1.07 to 1.21, and 1.05 to 1.42, respectively. As the value of the exergetic sustainability index is proportional to the exergy efficiency, the highest exergetic sustainability index values showed a slight impact on the environment, resulting in environmental imbalance and improvement of exergy efficiency.…”

Thermodynamic Evaluation of the Forced Convective Hybrid-Solar Dryer during Drying Process of Rosemary (Rosmarinus officinalis L.) Leaves

“…This increase leads to enhanced energy utilization. Similar results were found for okra drying in a compulsory convection cabinet dryer [36], mushroom slices in convective drying [37], and cassava starch drying in a tray dryer [38], in which researchers reported that the greater the input air temperature, the greater the energy consumption.…”

“…Therefore, to reduce this effect, the efficiency of exergy must be improved. Okunola, Adekanye and Idahosa [36] obtained an SI between 2.14 and 2.77. They reported that this value varies under the experimental conditions, and its value is proportional to the load density and has an inverse relationship with increasing temperature.…”

“…As shown in Figure 4, the effect of the input air velocity on exergy efficiency at low temperatures is considerably higher than at high temperatures. Yogendrasasidhar and Pydi Setty [43] reported an increase in exergy efficiency as temperatures rose from 40 to 60 • C. Okunola, Adekanye and Idahosa [36] reported that increasing the temperature to 70 • C caused energy efficiency to increase from 26.59% to 68.24%.…”

“…Yogendrasasidhar and Pydi Setty [43] reported an increase in exergy efficiency as temperatures rose from 40 to 60 °C. Okunola, Adekanye and Idahosa [36] reported that increasing the temperature to 70 °C caused energy efficiency to increase from 26.59% to 68.24%.…”