Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Citation - WoS: 3
    Citation - Scopus: 2
    Effects of Interphase Boundaries in Ginzburg-Landau One-Dimensional Model of Two-Phase States in Clamped Systems
    (American Institute of Physics, 2021) Levanyuk, Arkady P.; Minyukov, Sergey A.; Mısırlıoğlu, İbrahim Burç; Okatan, Mahmut Barış
    Previous Landau-type models of two-phase state formation in clamped systems whose material exhibits first-order phase transitions in free state neglects the existence of interphase boundaries. Here, we take them into account in the framework of a Ginzburg-Landau one-dimensional model to study the dependence of characteristics of the two-phase state on system size. Unlike earlier works, we find that the transition to the two-phase state from both the symmetrical and nonsymmetrical phases is not continuous but abrupt. For a one-dimensional system with length L studied in this work, we show that the formation of two-phase state begins with a region whose size is proportional to root L. The latent heat of the transition is also proportional to root L -> infinity, recovering the earlier result for infinite systems. The temperature width of the two-phase region decreases with decreasing of L, but we are unable to answer the question about the critical length for two-phase state formation because the approximation used in analytical calculations is valid for sufficiently large L. A region of small values of L was studied partially to reveal the limits of validity of the analytical calculations. The main physical results are also obtainable within a simple approximation that considers the energy of interphase boundary as a fixed value, neglecting its temperature dependence and the thickness of the boundary. A more involved but consistent treatment provides the same results within the accepted approximation and sheds light on the reason of validity of the simplified approach.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 17
    Experimental Investigation on Heat Transfer and Air Flow Behavior of Latent Heat Storage Unit in a Facade Integrated Ventilation System
    (Elsevier Ltd, 2021) Pekdogan,T.; Tokuç,A.; Ezan,M.A.; Başaran,T.
    All-air central HVAC systems are widely applied to provide fresh and conditioned air, which is very important for users to lead healthy and productive lives. Decentralized systems are another mechanical solution to ensure indoor air quality and thermal comfort with a heat recovery ventilation system integrated into the building wall. These commercially available systems store sensible energy in the heat exchanger. In this study, an experimental real-size staggered tube bundled prototype with phase change material (PCM), which stores latent thermal energy, was proposed/designed and full-scale experiments were carried out in laboratory conditions. The experimental setup includes two spaces that simulate indoor and outdoor conditions that are separated by an insulated aerated concrete wall. In the prototype, two ducts embedded in the wall contain staggered tube bundles filled with PCM, which are positioned perpendicular to the airflow to recover heat for supply and exhaust ventilation modes. The thermal performance of this prototype is investigated for different operating times, namely, 15, 20, and 30 min. The average air energy change of the latent heat recovery ventilation system values is between 20 and 35 kJ approximately for the operating times. The supply mode efficiency result is an average of 50% and exhaust mode efficiency is 25%. © 2021 Elsevier Ltd