Yazar "Agbulut, Umit" seçeneğine göre listele

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    Öğe
    Experimental analysis of CPV/T solar dryer with nano-enhanced PCM and prediction of drying parameters using ANN and SVM algorithms
    (Pergamon-Elsevier Science Ltd, 2021) Karaagac, Mehmet Onur; Ergun, Alper; Agbulut, Umit; Gurel, Ali Etem; Ceylan, Ilhan
    In this paper, a concentrated photovoltaic-thermal solar dryer (CPV/TSD) using nano-enhanced PCM (Al2O3Paraffin wax) is experimentally studied. A comprehensive thermodynamic analysis of the system according to the first and second laws is discussed. Besides, the drying parameters (moisture content and moisture ratio) are predicted using the two machine learning algorithms (ANN and SVM) and compared the prediction success with four evaluation metrics (R2, rRMSE, MBE, and rMAE). The overall thermal energy efficiency and exergy efficiency of the CPV/TSD system are found to be 20% and 8%, respectively. Although solar radiation to the environment has decreased a lot, it has been found that the thermal energy transferred to the nano-enhanced PCM prevents the decrease in greenhouse temperature for the first 100 min. In the system, mushrooms are dried from the initial moisture content of 17.45 g water/g dry matter to the final moisture content of 0.0515 g water/g dry matter. Then the drying rate value for CPV/TSD system is calculated to be 0.436 g matter/g dry matter.min. On the other hand, even if both ANN and SVM algorithms have exhibited very satisfying results, ANN is coming to the fore in the prediction of the drying parameters considering all evaluation metrics together.
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    Öğe
    Thermodynamic analyses of a novel hybrid photovoltaic-thermal (PV/T) module assisted vapor compression refrigeration system
    (Elsevier, 2023) Yildiz, Gokhan; Gurel, Ali Etem; Ceylan, Ilhan; Ergun, Alper; Karaagac, Mehmet Onur; Agbulut, Umit
    Buildings have a respectable share of global energy consumption and it is well-known that refrigeration, heating and air conditioning systems have crucially contributed to this share. Therefore, even a small improvement in these systems has a noteworthy potential in globally saving energy. Accordingly, the performance of Photovoltaic-Thermal module-assisted vapor compression refrigeration system (PV/T-VCRS) has been handled in the present research. PV/TVCRS has been integrated with PV module, refrigeration system, and their hybrid. Additionally, different from the conventional superheating methods, superheating has been performed with a PV/T module in this work. In order to discuss the system performance, and observe the differences between conventional and modified hybrid systems, energy and exergy analyzes have been applied. In the results, the average PV module surface temperature in PV module and PV/T-VCRS is recorded to be 56.16 degrees C and 40.93 degrees C, respectively. This case leads to a direct increment in PV module electrical efficiency. Electrical efficiency, average electrical efficiency in PV module, and PV/T-VCRS are calculated to be 13.49% and 14.69%, respectively. The average COP values are found to be 5.23 for VCRS, and 5.68 for PV/T-VCRS. Total exergy destruction in VCRS and PV/TVCRS has been calculated to be 175.85 W and 443 W. On the other hand, the exergy efficiency is found to be 50.79% in VCRS and 60.73% in PV/T-VCRS. In the conclusion, it is well-noticed that hybrid PV/T-VCRS presented promising results in terms of electrical efficiency, COP, energy, and exergy analyses as compared to those of the conventional system.