Browsing by Author "Mercan, M"

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    EFFECTS OF ENVIRONMENTALLY FRIENDLY FLUIDIZED BED DRYING ON THE QUALITY OF Viburnum opulus
    Bölek, S; Mercan, M; Vursavas, M; Arslan, D; Yurddas, A
    Owing to their high antioxidant activity, fiber, vitamin and mineral content, dried fruits are healthy and nutritious snacks. However, some quality characteristics of fruits are adversely affected by drying. Therefore, drying temperature is very important to obtain healthy and nutritious dried products. Recently, fluidized bed drying technology has been spread all over the world as it is an efficient and environmentally friendly technique. This study investigated the effects of fluidized bed drying, which is a thermodynamic equilibrium drying technique, on quality characteristics of Viburnum opulus. For this aim, the V. opulus fruits were dried at 60 degrees C, 70 degrees C and 80 degrees C with an air flow rate of around 60 m(3)/h for 5 h, 4 h and 3 h respectively. The moisture contents of V. opulus fruits were reduced by half (for medium-high temperature cases) after 90 min of drying process. Thanks to environmentally friendly fluidized bed drying system, V. opulus fruits moved on the bed during drying. As the fruits did not stay in the same place, heat and mass transfer increased and uniform drying was achieved. Color, rehydration capacity, shrinking ratio, antioxidant activity, pH and sensory analysis were conducted to compare the sensory, chemical and physical properties of dried V. opulus fruits. The drying temperature affected the quality characteristics of V. opulus fruits significantly (p<0.05). The V. opulus fruits dried at 60 degrees C has the highest rehydration capacity and they were the most appreciated samples with regards of appearance, flavor and overall impression among the dried fruits (p<0.05).
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    Chronic pain after Lichtenstein and preperitoneal (posterior) hernia repair
    Erhan, Y; Erhan, E; Aydede, H; Mercan, M; Tok, D
    Background: Hernia repair is one of the most common surgical procedures, and some patients suffer from chronic pain after hernia surgery. The aim of the present study was to evaluate chronic post-herniorrhaphy pain in men who underwent Lichtenstein mesh repair or preperitoneal (posterior) repair. Methods: Our study included 94 male inpatients. Two surgeons experienced in both Lichtenstein and preperitoneal hernia repair performed the procedures. We controlled postoperative pain with systemic analgesic therapy. We evaluated the patients over the subsequent 12 months, using a questionnaire to focus on chronic pain and its limitations to their quality of life. Results: The overall incidence of chronic pain at 2 months was 5%. About 6% of patients who underwent Lichtenstein repair (n =70) and 4% of patients who underwent preperitoneal repair (n =24) experienced chronic pain. All patients with chronic pain rated their pain as slight or moderate. Their pain was present occasionally and was related to physical stress. None of the patients were unable to work. After 12 months of follow-up, the overall incidence of chronic pain decreased to 3%, with 3 patients in Lichtenstein group reporting chronic pain with slight limitations in sports and social activities. Conclusion: The incidence rates of chronic pain after Lichtenstein and preperitoneal repair were 6% and 4%, respectively. Inpatient status might have resulted in low incidences with both approaches.
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    Numerical analysis of evacuated tube solar collectors using nanofluids
    Mercan, M; Yurddas, A
    In this study, numerical analysis of water and water based nanofluids in ETSCs were made by using CFD. Validation of the study was made by comparing an experimental and two different numerical results. Thanks to the analyzes, the effects of water based Al2O3-H2O and CuO-H2O nanofluids compared to water on heat transfer for different volume fractions of nanoparticle, different collector angles, different mass flow rates and different numbers of evacuated tubes were examined. According to these parameters, the thermal and hydraulic statuses of the collector were examined by using the Boussinesq approximation and the tank outlet temperatures were determined. It has been determined that the use of nanofluid in ETSC systems has improved heat transfer and the best improvement was obtained with CuO-H2O nanofluid.