Seyfi Şevik

Determination of drying kinetics and quality parameters of grape pomace dried with a heat pump dryer

Pomace of Hamburg Muscat was dried at temperature of drying air 45 °C and different air velocity (1.5, 2.0 and 2.5 m/s) in open-loop heat pump (HP) and laboratory-type closed-loop dryer (as a control). In the HP dryer, it was concluded that drying air velocity was slightly effective on drying time however there is no significant effect on the power consumption of the change in the drying air velocity at the same temperature. When comparing the energy consumption of the HP dryer and convective dryer, the energy consumption was reduced by up to 51%. In HP drying, the increase of air velocity from 1.5 m/s to 2.5 m/s caused a reduction in drying time by 69%. It was observed that part of the bioactive properties was lost in pomace samples but there were fewer losses in all bioactive properties than the others except the total anthocyanin at 2 m/s.

Drying of grape pomace with a double pass solar collector

ABSTRACT This study aims to analyze the performance of a novel design of the double pass solar air collector (DPSAC)-assisted drying system and investigate the drying kinetics of grape pomace which is an agricultural by-product. The samples were dried to a moisture content of 0.01 g water/g dry matter between 100 and 250 min depending on the weather conditions. The average thermal efficiencies of DPSAC were calculated as 79.77, 79.85, and 69.46%. Average values of the coefficient of performance of DPSAC were determined as 5.32, 5.13, and 4.32. The highest specific moisture extraction rate value was achieved as 617.18 g water/kWh. Whereas the mass transfer coefficient (hm) values ranged from 9.15E−11 to 1.04E−7 m/s, the effective moisture diffusivity (De) values were obtained between 3.04E−13 and 1.02E−10 m2/s. The qualitative analysis showed that the drying using DPSAC may be an alternative for drying applications in terms of short drying time and energy usage. Nevertheless, these results clearly suggest a complex and effective interplay between thermal performance and drying kinetics.