Determination of Sliced Pineapple Drying Characteristics in a Closed Loop Heat Pump Assisted Drying System

Pineapple (Ananascomosus) slices were dried with the aid of a heat pump assisted dryer (HPD). During this process, air velocity was kept constant at 1m/s, while air temperatures were changed as 37°C, 40°C and 43°C. The drying air was also circulated by using an axial fan in a closed cycle and fresh air was not allowed into the system. The drying rate and drying time were significantly influenced by drying temperature. It was observed that drying temperatures had significant effects on the drying rate and drying time. During the conduct of the study, pineapple slices were dried at 37, 40 and 43°C for 465, 360 and 290 min, respectively. The specific moisture extraction ratio (SMER) values were observed to change as drying temperatures were changed. The drying rate curves indicated that the whole drying process occurred in the falling rate period. Seven well-known thin-layer models (Lewis, Henderson &Pabis, Logarithmic, Page, Midilli & Kucuk, Weibull and Aghbashlo et al.) were employed to make a prediction about drying kinetics through nonlinear regression analysis. The Midilli & Kucuk and Aghbashlo et al. models were consistent with the experimental data. Fick\u27s second law of diffusion was used to determine the moisture diffusivity coefficient ranging from 3.78×10–9 to 6.57×10-9 m2/s the each of the above mentioned temperatures. The dependence of effective diffusivity coefficient on temperature was defined by means a fan Arrhenius type equation. The activation energy of moisture diffusion was found to be 75.24kJ/mol. Article History: Received: July 18th 2017; Received: October 27th 2017; Accepted: January 16th 2018; Available onlineHow to Cite This Article: Tunçkal, C., Coşkun, S., Doymaz, I. and Ergun, E. (2018) Determination of Sliced Pineapple Drying Characteristics in A Closed Loop Heat Pump Assisted Drying System. International Journal of Renewable Energy Development, 7(1), 35-41.https://doi.org/10.14710/ijred.7.1.35-4

EFFECT OF PRE-TREATMENT AND AIR TEMPERATURE ON DRYING KINETICS AND QUALITY OF JERUSALEM ARTICHOKE

The effect of pre-treatment and air temperature on the drying kinetics and some quality criteria of Jerusalem artichoke were investigated. The pre-treated and untreated of Jerusalem artichoke slices were dried in a cabinet dryer at temperatures of 60, 70 and 80 °C. It was found that air temperature and pre-treatment had more significant effects on drying kinetics, color and rehydration ratio. The experimental data were adjusted to seven thin-layer drying models in the representation of vegetable and fruit drying. The Midilli & Kucuk model was best fitted to measurements. The effective moisture diffusivity at each temperature was determined by Fick’s second law of diffusion, in which their value varied from 5.49×10–10 to 1.90×10-9 m2·s-1 over the mentioned temperature range. The values of the activation energy of moisture diffusion were 50.74 and 40.21 kJ·mol-1 for citric acid and control samples, respectively

Drying Kinetics and Rehydration Characteristics of Convective Hot-Air Dried White Button Mushroom Slices

The effect of pretreatment (0.5% citric acid solution) and drying air temperature (40, 50, 60, and 70°C) on drying characteristics of button mushroom slices was investigated in a cabinet dryer. The experimental results show that the drying temperature and pretreatment have significant effects on the moisture removal from mushroom. In addition, rehydration ratio of pretreated samples was higher than that of control ones. Four kinds of classical model were used to obtain moisture data and the logarithmic model was the best for representation of mushroom drying. The values of effective moisture diffusivity were found to range between 1.70×10-10 and 7.12×10-10 m2/s over the temperature range studied. The activation energy was found to be 35.04 and 37.21 kJ/mol for control and pretreated samples, respectively

Drying of green bean and okra under solar energy

In this study, sun drying characteristics of green bean and okra were investigated. Drying experiments were conducted in Iskenderun-Hatay, Turkey. The drying study showed that the times taken for drying of green bean and okra from the initial moisture contents of 89.5% and 88.7% (w.b.) to final moisture content of around 15±0.5% (w.b.) were 60 and 100 h in open sun drying, respectively. The constant rate period is absent in drying curves. The drying process took place in the falling rate period. The drying data were fitted to thirteen thin-layer drying models. The performance of these models was investigated by comparing the determination of coefficient (R2), reduced chi-square (2) and root mean square error (RMSE) between the observed and predicted moisture ratios. Estimations by Approximation of diffusion (for green bean) and Midilli et al. models (for okra) were in good agreement with the experimental data obtained

Effect of hot air drying on quality characteristics and physicochemical properties of bee pollen

Abstract The aim of this study was to investigate the effect of hot air drying on quality characteristics, physicochemical properties, morphological structure and organoleptic characteristics of bee pollen, and compute the effective moisture diffusivity and activation energy during hot air drying of bee pollen. Bee pollen samples were dried at 40, 45, 50, 55 and 60 °C. Effective moisture diffusivity (Deff) values ranged from 1.38 × 10 −10 to 4.00 × 10−10 m2/s, and the activation energy (Ea) was found to be 42.96 kJ/mol. Protein, fat, total carbohydrates and vitamin C of bee pollen were affected by the drying temperature. Dried bee pollen samples had high solubility index, and had lower L* and b* values as compared with those of the fresh bee pollen. Total color difference (Δ E) was the lowest for the bee pollen dried at 40 °C. Morphological changes on dried bee pollen surfaces increased with increasing the drying temperature. Bee pollen dried at 40 °C took the highest sensory scores and retained its quality attributes better than the bee pollen samples dried at 45, 50, 55 and 60 °C. Hot air drying at 40 °C is recommended for the drying of bee pollen

Determination of Sliced Pineapple Drying Characteristics in A Closed Loop Heat Pump Assisted Drying System

Pineapple (Ananascomosus) slices were dried with the aid of a heat pump assisted dryer (HPD). During this process, air velocity was kept constant at 1m/s, while air temperatures were changed as 37°C, 40°C and 43°C. The drying air was also circulated by using an axial fan in a closed cycle and fresh air was not allowed into the system. The drying rate and drying time were significantly influenced by drying temperature. It was observed that drying temperatures had significant effects on the drying rate and drying time. During the conduct of the study, pineapple slices were dried at 37, 40 and 43°C for 465, 360 and 290 min, respectively. The specific moisture extraction ratio (SMER) values were observed to change as drying temperatures were changed. The drying rate curves indicated that the whole drying process occurred in the falling rate period. Seven well-known thin-layer models (Lewis, Henderson &Pabis, Logarithmic, Page, Midilli & Kucuk, Weibull and Aghbashlo et al.) were employed to make a prediction about drying kinetics through nonlinear regression analysis. The Midilli & Kucuk and Aghbashlo et al. models were consistent with the experimental data. Fick’s second law of diffusion was used to determine the moisture diffusivity coefficient ranging from 3.78×10–9 to 6.57×10-9  m2/s the each of the above mentioned temperatures. The dependence of effective diffusivity coefficient on temperature was defined by means a fan Arrhenius type equation. The activation energy of moisture diffusion was found to be 75.24kJ/mol.   Article History: Received: July 18th 2017; Received: October 27th 2017; Accepted: January 16th 2018; Available online How to Cite This Article: Tunçkal, C., Coşkun, S., Doymaz, I. and Ergun, E. (2018) Determination of Sliced Pineapple Drying Characteristics in A Closed Loop Heat Pump Assisted Drying System. International Journal of Renewable Energy Development, 7(1), 35-41. https://doi.org/10.14710/ijred.7.1.35-4

Modeling and Investigation of the Swelling Kinetics of Acrylamide-Sodium Acrylate Hydrogel

The acrylamide-sodium acrylate hydrogel was synthesized by free radical polymerization of the method of solution polymerization. Dynamic swelling tests were conducted at 25, 40, and 60°C temperatures, in order to investigate the swelling properties of the synthesized hydrogel. The results have shown that swelling content and swelling rate of the hydrogel increase with increasing the swelling water temperature. The diffusivity values changed from 1.81×10-7 to 2.97×10-7 m2 s−1 over the temperature range. The activation energies were found as 3.56, 3.71, and 3.86 kJ mol−1 at 25, 40, and 60°C, respectively. The experimental drying curves obtained were fitted to a three different models, namely, Peleg’s, first-order absorption kinetic, and exponential association equation models. All the models applied provided a good agreement with the experimental data with high values of the coefficient of determination (R2), the least values of the reduced chi-square (χ2), and root mean square error (RMSE). Comparing the determination of coefficient, reduced chi-square, and root mean square error values of three models, it was concluded that the exponential association equation model represents swelling characteristics better than the others