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    Drying of grape pomace with a double pass solar collector
    (Taylor and Francis Inc., 2019) Aktaş, Mustafa; Şevik, Seyfi; Dolgun, Ekin Can; Demirci, Burhan
    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 (h m ) values ranged from 9.15E?11 to 1.04E?7 m/s, the effective moisture diffusivity (D e ) values were obtained between 3.04E?13 and 1.02E?10 m 2 /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. © 2018, © 2018 Taylor & Francis.
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    Heat pump drying of grape pomace: Performance and product quality analysis
    (Taylor and Francis Inc., 2019) Aktaş, Mustafa; Taşeri, Levent; Şevik, Seyfi; Gülcü, Mehmet; Uysal Seçkin, Gamze; Dolgun, Ekin Can
    Grape is one of the most popular fruits and various types of grape have been cultivated by more than 100 countries around the World. The wine and juice industry produces large quantities of by-product, called grape pomace (GP) as an industrial waste and it consists of skins, seeds, and stems. Various processes such as separation, pressing, drying, and milling are applied to benefit from its health effects. In this study, the seeded black GP Kalecik karası (Vitis vinifera) was dried in an assisted closed cycle heat pump dryer (HPD) designed for high-moisture products to investigate the drying behaviors of GP. The effects of drying air temperature on bioactive properties and the drying characteristics of GP, and performance of system have discussed. Experiments were carried out at two different temperatures (45 and 50°C) and air velocity of 1.0 m/s. It was seen that increasing temperature decreased the drying time, coefficient of performance of whole system (COPws), and specific energy consumption (SEC). The average values of COPws for temperatures 45°C and 50°C were calculated as 3.28 and 3.10, respectively. The drying efficiencies (DE) at drying air temperature of 45°C and 50°C ranged from 2 to 12% and from 2 to 15%, respectively. Additionally, result of analysis has indicated that using a HPD at lower temperatures increases performance of system despite of higher energy input. Bioactive properties of dried samples at drying air temperature of 45°C are better than 50°C. The results show that drying the GP at low temperature is more suitable for product quality. For this reason, heat pump may be preferred. It shows that this drying system with higher capacities in the future can be recommended as an alternative technique in terms of energy usage, drying time, and performance of system. © 2018, © 2018 Taylor & Francis Group, LLC.
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    Öğe
    Performance analysis of solar and solar-infrared dryer of mint and apple slices using energy-exergy methodology
    (Elsevier Ltd, 2019) Şevik, Seyfi; Aktaş, Mustafa; Dolgun, Ekin Can; Arslan, Erhan; Tuncer, Azim Doğuş
    In this study, double-pass solar air dryer (DPSAD) and infrared assisted double-pass solar air dryer (DPSAIRD) were designed and tested. The effects of using infrared energy have been experimentally investigated to ensure continuity in climatic conditions (cloudy, etc.) where solar energy is insufficient. Comparative experiments were carried out in the summer and autumn. Energy and exergy analysis, mass and heat transfer, performance coefficient, specific energy consumption, drying efficiency, energy efficiency and error bars have been used as criteria for evaluating thermal and structural performance of solar dryer and to see the effects of infrared energy on dried products (apple slices and mint leaves). The highest thermal efficiency of the collector was obtained as 83.56%. For DPSAIRD and DPSAD, exergy efficiency values were calculated as 49.17%, 59.07%, 59.06% and 69.35%, respectively. Energy efficiencies varied between 1.15% and 8.59% for DPSAIRD, 2.20% and 26.46% for DPSAD. Despite the low radiation values in autumn and the lower ambient temperature, it was found that the drying times are almost the same as in the summer months, thanks to the use of infrared energy. The IR lamp significantly increased energy consumption; however, in cases where the collector was insufficient, it supported both the collector and protected the products against deterioration. © 2019