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ÖZDEMİR, MEHMED RAFET

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ÖZDEMİR

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MEHMED RAFET

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2016 - 20194
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End date: 2019 × Has files: true ×

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Now showing 1 - 4 of 4
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    EFFECT OF THE GEOMETRICAL PARAMETERS IN A DOMESTIC BURNER WITH CRESCENT FLAME CHANNELS FOR AN OPTIMAL TEMPERATURE DISTRIBUTION AND THERMAL EFFICIENCY
    (YILDIZ TECHNICAL UNIV, 2019-12-02) ÖZDEMİR, MEHMED RAFET; Sener, Ramazan; Ozdemir, Mehmed R.; Yangaz, Murat U.
    Domestic cookers are common tools of house appliances in the world and they have significant share in global energy consumption. Therefore, a small amount of improvement in efficiency would result in a huge drop in total energy and resource activity. This study aims at presenting numerically the thermal efficiency of a domestic burner with crescent-shaped flame channels by changing the distance from the cooker to the burner head and the diameter of the burner. The energy efficiency parameter was evaluated analyzing temperature distribution along the bottom surface of the cooker and unburnt HC, CO and NO emissions. Simulations have been carried out with methane as fuel for three different diameter and distance parameters. The results showed that the temperature on the surface and the emission values of unburnt CO, NO and HC decreased with increasing the cooker diameter and distance parameter.
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    PublicationOpen Access
    EXERGO-ECONOMIC ANALYSIS OF MICROCHANNELS IN SINGLE-PHASE FLOW
    (YILDIZ TECHNICAL UNIV, 2018-06-30) ÖZDEMİR, MEHMED RAFET; Ozdemir, M. R.; Sozbir, O. R.; Yilmaz, M.
    With the increase of energy demand, many researchers tried to develop scientific approaches in order to design more efficient and environmentally friendly energy systems. Exergo-economic (thermoeconomic) analysis of a system or device is an efficient tool for evaluating the system in terms of the thermodynamic and economic aspects. In this parametric study, exergo-economic analysis of rectangular copper plain microchannels under single-phase flow conditions were investigated using de-ionised water. The exergo-economic performance was evaluated based on the relative cost difference and unit cost per product exergy tools. The channel aspect ratio effect on the unit cost per product exergy and relative cost difference was examined using three microchannel test sections with the same channel hydraulic diameter (D-h = 0.56 mm) and length (L = 62 mm) but different aspect ratios beta = 0.5, 2.56 and 4.94) under single-phase flow conditions. The results showed that the exergo-economic performances of the three microchannel test sections decreased as the net heat input increased over the experimental range. Moreover, the exergo-economic performance of test section 2 (beta = 4.94) was found to be greater than the exergo-economic performances of test sections 1 and 3 (beta = 0.5 and 2.56) at fixed flow rate and fixed net heat input case.
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    PublicationOpen Access
    FLOW BOILING HEAT TRANSFER IN A RECTANGULAR COPPER MICROCHANNEL
    (YILDIZ TECHNICAL UNIV, 2016) ÖZDEMİR, MEHMED RAFET; Ozdemir, Mehmed R.; Mahmoud, Mohamed M.; Karayiannis, Tassos G.
    Flow boiling characteristics of de-ionized water were tested experimentally in a rectangular copper single microchannel of 1 mm width, 0.39 mm height and 62 mm length. De-ionized water was supplied to the microchannel at constant inlet temperature (89 degrees C) and constant inlet pressure (115 kPa). The mass flux ranged from 200 to 800 kg/m(2)s and the heat flux from 56 to 865 kW/m(2). The heat transfer rate data are presented as plots of local heat transfer coefficient versus vapour quality and distance along the channel. Flow visualization was also conducted using a high-speed, high-resolution camera. The results indicate that unstable flow boiling occurred starting at boiling incipience for all mass flux values. The local heat transfer coefficient depends on heat flux only at very low heat and mass fluxes. At high mass flux, there is no heat flux effect with little dependence on vapour quality after the entry region. The mass flux effect was more complex.