Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Energy Performance Analysis and Materials Characterization of Aerogel Insulation Blankets(Izmir Institute of Technology, 2022) Alan, Selena; Gökçen Akkurt, Gülden; Akkurt, Sedatİzmir Geothermal Energy Inc. is a geothermal district heating company in İzmirTurkey that circulates hot water throughout the district via a 450 km of piping system and with the help of valves, pipes, and heat exchangers. As the distance traveled by the hot water is excessively long, heat losses are common. Rock wool is used as thermal insulation material, but the performance degraded over time because of water leakage. Instead of rock wool, aerogel insulation blanket use is evaluated in this study. Rock wool and three different aerogel insulation blankets are comparatively studied to assess their structures and thermal performances in two ways: the first is the characterization of materials by various physical and chemical analysis methods in the IZTECH-Integrated Research Center. The second way is to assemble a test setup on-site and make thermal measurements on the test setup for each aerogel insulation material, rock wool, and bare pipe. Heat loss calculations were conducted by EES software. The results are compared based on each characterization and thermal performance calculation. The thermal conductivity values of the insulation materials were calculated. Nonwetting properties were also checked to understand their hygrothermal properties. Compared with bare pipe, with the 10 mm thickness, rock wool decreases heat loss by 48-52%, and with the 10 mm thickness, the aerogel insulation blankets reduce heat loss by 57-61%. Finally, while aerogel insulation blankets have a better performance, they are more expensive than rock wool.Master Thesis An Experimental Investigation Into the Effects of High Thermal Mass on Building Performance(Izmir Institute of Technology, 2019) Karataş, Özgür; Başaran, TahsinThe focus on energy efficiency in buildings has contributed to the increased interest in vernacular architecture using locally available materials. Monotype architecture has spread across Anatolia during last century despite builders having centuries of knowledge of vernacular dwelling. Climatic conditions are specific to geographical locations, therefore the architectural solutions respecting climatic conditions are also specific. Local construction materials are in harmony with the surroundings because they have previously been part of the current environment. The main aim of this thesis is to investigate and simulate the effects of high thermal mass on the thermal environment of cave dwellings. The case study was undertaken in a cave dwelling carved out of a fairy chimney in Ürgüp, Cappadocia. Data loggers were placed in the dwelling to observe the annual temperature and relative humidity fluctuations. Measurements showed that the interior temperature fluctuated around 18°C in January and 20°C in July, and the relative humidity fluctuated around 70% in January and 65% in July. These measurements showed that the interior conditions were thermally comfortable as a result of the high thermal mass of the cave dwelling. DesignBuilder software was used to simulate the thermal behaviour of the cave dwelling. The thermal conductivity, specific heat and density of the main material, volcanic tuff rock, were measured and defined in DesignBuilder. After defining all the inputs and boundary conditions, the numerical results obtained from the DesignBuilder provided thermal outputs which agreed with the experimental results.Master Thesis Event Distortion Based Clustering Algorithm for Energy Harvesting Wireless Sensor Networks(Izmir Institute of Technology, 2017) Al-Qamaji, Ali Mudheher Raghib Kafi; Atakan, Barış; Atakan, BarışWireless Sensor Network (WSN) is a set of inexpensive densely deployed wireless sensor nodes with limited functionalities and scarcity in energies, whose observations are forwarded or relayed by intermediate nodes to the Base Station (BS). In the networks with densely deployed nodes, the observations are likely to be highly correlated in the space domain. This type of correlation is referred as spatial correlation, which produces unfavorable redundant readings causing energy wasting. In this thesis, the main task is to reduce these nodes that have redundant readings by using a clustering algorithm called Event Based Clustering (EDC) algorithm. The clustering algorithm is based on exploiting the spatial correlation that is used to cluster the sensor nodes. Exploiting spatial correlation is proposed by using Vector Quantization (VQ) with respect to the distortion constraints. Furthermore, this algorithm is applied for energy harvesting sensor nodes. Also, the inessential sensor nodes that have correlated readings are reduced for improving the Energy-Efficacy (EE) with acceptable level of event signal reconstruction distortion at the sink node. After applying the EDC algorithm, the communication model is changed from single-hop model to two-hop (clustered-network) model. Hence, a theoretical framework of distortion function, i.e., accuracy level, for both single-hop and two-hop communication models is derived. Then, single-hop and two-hop communication models are compared in terms of achieved distortion level, number of alive nodes, and energy consumption for different sizes of event area. Finally, the effects of various harvested energy level on the clustered-network is studied with respect to the same terms.Master Thesis An Investigation of Transient Thermal Behaviors of Building External Walls(Izmir Institute of Technology, 2015) Pekdoğan, Tuğçe; Başaran, TahsinHeat transfer problem of the building opaque wall surfaces are highly important for providing thermal comfort for different climatic conditions and orientations. In this study, the insulation models with external, internal and center positioned insulation materials are parametrically analyzed regarding their time dependent thermal behaviors. One-dimensional time-dependent heat conduction equation is investigated by solving via implicit finite difference method for summer and winter climatic conditions; and north, south, east and west orientations. Meteorological data for Ankara, Erzurum, İstanbul and İzmir, which are cities with different climatic conditions, are used in these calculations. The results indicate that, sandwich wall insulated type gives more convenient results regarding the heating loads for winter and cooling loads for summer, for each investigated city and directions.