Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2023/r/gumushane/12811
  Energy, exergy analysis and optimization of insulation thickness on buildings in a low-temperature district heating system

  Terhan, Meryem; Abak, Sena Saliha

  In the study, energy and exergy analysis of the buildings on a campus in Turkey are conducted by using actual operating data and taking measurements in the district heating system as a case study. The energy and exergy demands, losses that stem from all buildings are calculated according to average daily outdoor temperature data. Due to the high heat losses in the buildings, determining the optimal insulation thickness for the exterior wall should be investigated. Therefore, optimal insulation thicknesses, energy savings, fuel consumptions and payback periods of the insulation material on the exterior wall of the building are examined by using Life Cycle Assessment and P1–P2 method for natural gas. Optimal insulation thicknesses are calculated for different insulation materials such as XPS, glass wool, rock wool and EPS for the climatic regions (HDD=800–4250°C days). According to average exergy losses from the building components per unit area, the average total exergy loss is calculated as 2.39×10-2 kW/m2.year and 1.42×10-3 kW/m2 (5.92%) of this loss stems from the exterior walls, 1.93×10-3 kW/m2 (8.07%) from the floors, 7.37×10-4 kW/m2 (3.08%) from the roofs, 1.58×10-2 kW/m2 (65.99%) from the windows and doors, 4.04×10-3 kW/m2 (16.92%) from the ventilation with infiltration. Energy requirement values of the building are found between 2.68–25.70 kWh/m3 towards from the warmest to the coldest climatic region for the uninsulated wall. In the un-insulated state, fuel consumption varies between 1.93-18.48 m3/m2 from the warmest to the coldest region. The optimal insulation thickness values of the building’s exterior wall are calculated as between 2.3–10.0 cm according to different climatic regions. In-state of exterior wall insulation of 3 cm, fuel consumption decreases by 46.63%–53.46% compared to different insulation materials and climatic regions compared to the un-insulated state

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• MakaleAçık Erişim2021/r/gumushane/14835
  PREDICTION SULPHURIC ACID AND WATER VAPOUR DEW POINT TEMPERATURES OF FLUE GASES AND COMBUSTION ANALYSIS FOR SOLID FUELS IN TURKEY

  Terhan, Meryem

  In the study, the combustion analysis is examined for the solid fuels in Turkey. The principal aim of the analysis is determined the limits and obstacles in the design heat exchanger to avoid the corrosion risk on the heat exchanger surfaces in the latent heat recovery applications from waste flue gas. To do this, in which regions of the heat exchanger the flue gas temperature reached to the sulphuric acid and water vapour dew point temperatures are required to predict. In order to predict the condensing zone, an air preheater for the coal-fired boiler in a heating system is designed using finite difference method. Designed the air preheater is consists of the counter-cross flow, U-shaped stainless steel tube bundle. The tube is discredited 200 cells to one-dimensional during the flow. The heat transfer rates, the flue gas and air inlet and outlet temperatures, surface temperatures of the tube wall, the mole fractions of water and sulphuric acid vapour, the other non-condensing gases in the flue gas are calculated in each discrete cell. According to the results of the study, while the dew point temperature of the water vapour changes over the range 30-40 °C, the acid dew point temperature waves to 125 °C from 140 °C for the coal types mined in Turkey.

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• Derleme MakaleAçık Erişim2018/r/gumushane/10289
  A REVIEW OF FLOW BOILING IN MINI AND MICROCHANNEL FOR ENHANCED GEOMETRIES

  Çebi, Alican; Celen, Ali; Donmez, Aydin Haci; Karakoyun, Yakup; Celen, Pinar; Cellek, Mehmet Salih; Dalkiliç, Ahmet Selim; Taner, Tolga; Wongwises, Somchai

  Flow boiling researches in enhanced geometries practiced recently have been summarized in this review. Classical approximations in macroscale flows have not applied to the flows with small hydraulic diameters, so, this subject has been paid attention by the researchers. Application areas of these structures are increasing continuously due to cooling need in small confined spaces. The related studies have been reviewed in a chronological manner and their parameters have been given in a table in order for the researchers to observe the scientific duration regarding the progresses on this subject. Almost all papers on this subject have been produced after 2000, therefore, this subject is considered as an actual one to improve and worth to study in the literature. This study can not only be evaluated as the beginning argument for the researchers involved in flow boiling process in mini and microchannel, but it also consists of new works on the investigated subject.

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