Browsing by Author "Celik, Hasan"

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Numerical Simulation of Different Ventilation Systems in an Airplane Cabin
(2022-12-26) Özerdem, Barış; Bilir, Levent; Celik, Hasan
Airplanes are the most popular way of transportation worldwide, especially for long haul. It facilitates the growth of global trade as well, besides promoting tourism and other employment developments. Passenger comfort and hygiene inside an airplane cabin became main concern for aircraft manufacturers. The possibility for a potential spread of infectious virus or bacteria even maximized this concern. Therefore, supplying sterile and particle-free air inside the aircraft cabin became extremely crucial more than ever. In order to ensure comfort and hygiene, regardless of the environment conditions inside the aircraft cabin, paved the way for researchers to focus on this topic, recently. It is obvious that, an important precaution for the spread of micro-organisms can be selecting an adequate air ventilation system inside the airplane cabin. In this study, a part of an airplane passenger cabin is modelled for four different scenarios. The streamlines of air, which is sent to the cabin from air ducts, are obtained and air flow path is observed for the investigated cases. The results of the numerical simulations are presented as the outcomes of this study. It is observed that the air mixing between different seat rows occur slightly only for sidewall supply and bottom return mixing ventilation and displacement ventilation systems, whereas the air mixing for the same seat row is seen for all ventilation systems. In conclusion, sidewall supply and bottom return mixing ventilation system is found the most appropriate one, even though it causes air recirculation at the same row seats.
Citation - WoS: 44
Citation - Scopus: 47
Recent Studies on 3d Lattice Metal Frame Technique for Enhancement of Heat Transfer: Discovering Trends and Reasons
(Pergamon-Elsevier Science Ltd, 2022-10) Caket, Ahmet Guray; Wang, Chunyang; Nugroho, Marvel Alif; Celik, Hasan; Mobedi, Moghtada
A Lattice Metal Frame (LMF) has advantages such as easy design of topology and shape of structure, and consequently easy controlling of pressure drop and heat transfer. The aim of this study is to review the reported studies on heat and fluid flow in 3D LMFs in different heat transfer areas and to categorize the reported studies focused on the forced convection heat transfer enhancement. The categorization is done based on the studied domain, structure topography, analysis approaches, solid and fluid materials, solution method and the selection of reference temperature and characteristic length for definition of dimensionless numbers such as Reynolds and Nusselt numbers. It is found that for enhancement of heat transfer in channels with cubic, tetrahedral, kagome, wire woven and octet struts were received the highest attentions among different structure. Furthermore, in this study, the values of friction factor, Nusselt number and efficiency index of the studies on single layer LMF defined channel height as characteristic length are also compared and discussed. It is found that X type structure with OA flow arrangement has the highest friction factor as well as Nusselt number while X type with OB flow arrangement has the highest efficiency index (thermos-hydraulic performance). It is suggested to separate the solution approaches into two groups as single layer (such as fin approach) and multilayer (such as volume average) approaches. Unification of characteristic length and reference temperature difference used by researchers will accelerate studies in this field.
Citation - WoS: 12
Citation - Scopus: 12
Thermal Analysis of Solid/Liquid Phase Change in a Cavity With One Wall at Periodic Temperature
(Mdpi, 2021-09-19) Tomita, Shogo; Celik, Hasan; Mobedi, Moghtada
In this study, heat transfer in a square cavity filled with a Phase Change Material (PCM) under a sinusoidal wall temperature during solidification and melting is analyzed. All surfaces of the cavity are insulated except one surface, which is under the sinusoidal temperature change. The governing equations and boundary conditions are made dimensionless to reduce the number of governing parameters into two as dimensionless frequency and Stefan number. The governing equations were solved numerically by using Finite Volume Method for a wide range of Stefan number (0.1 < Ste < 1.0) and dimensionless frequency (0.23 < omega* < 2.04). Based on the obtained results, a chart in terms of Stefan number and dimensionless frequency is obtained to divide the heat transfer process in the cavity into three regions as uncompleted, completed, and overheated phase-change processes. For the uncompleted process, some parts of the cavity are inactive, and no phase change occurs in those parts of the cavity during the melting and freezing process. For the overheated phase change, the temperature of the cavity highly increases (or decreases), causing the sensible heat storage to compete with latent thermal storage. In the completed process, almost all thermal storage is done by the utilization of latent heat. The suggested graph helps thermal designers to avoid wrong designs and predict the type of thermal storage (sensible or latent) in the cavity without doing any computations.