Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Evaluation of Thermal Comfort Conditions During Training in Physical Fitness Spaces(01. Izmir Institute of Technology, 2024) Avcı, Ali Berkay; Başaran, TahsinPresently, fitness centers have become extensively occupied spaces. These higher-activity-level spaces require different thermal comfort parameters than other indoor environments. Therefore, it is crucial to provide the comfort that users need during their physical exercise. Human body during exercise requires different thermal comfort conditions and higher fresh air supply rates than sedentary activities. The standards for fitness centers do not provide specialized thermal and spatial instructions for the fitness spaces. This thesis focuses on investigating the thermal and spatial conditions of exercise spaces. To determine ideal exercise space conditions, a thermal and flow analysis involving experiments and 3D simulations in a computer environment were employed. The study specifically examined spatial factors such as ceiling height, lateral and frontal distances between machines, and vent locations, along with thermal factors like inlet temperature and air velocity. A thirty-minute constant work rate exercise test at moderate intensity was conducted in a controlled climatic chamber with six participants. The experiment's conditions were replicated and verified in CFD software using the collected data. Then, computational models for various environmental and spatial scenarios for a five-person cycling class were generated. Employing the L9 orthogonal arrays method, nine spatial scenarios with three thermal operations were simulated. Optimal factor levels were determined based on thermal comfort conditions by predicted mean vote (PMV) around the thermal plumes. The findings indicated that a ceiling height of 5m, lateral and frontal distances of 1m and 0.5m between machines, and ventilation strategy with ceiling located inlets at a condition of 18°C and 0.2m•s-1 performed optimal results.Doctoral Thesis Investigations of Indoor Thermal and Air Flow Conditions in a Tobacco Warehouse(01. Izmir Institute of Technology, 2023) Gerçek, Mümine; Başaran, TahsinThis study investigates the thermal performance and indoor environment conditions of naturally and hybrid ventilated industrial buildings. Numerical analyses and experimental measurements were conducted in a tobacco warehouse in İzmir, Turkey. Parametric analyses were performed with three different approaches: i) 15 architectural design strategies are evaluated by using a sensitivity analysis. It is found that roof insulation thickness, shading projection factor, and shading angle have significant impact on heating and cooling requirements. In addition, the most influential factors on operational CO2 emissions are thickness of insulation material and conductivity of thermal insulation material. ii) Vertical and volumetric temperature gradients, crucial for stored product quality, are assessed through field measurements and CFD simulations. Ceiling-mounted radiant cooling systems reduced indoor temperatures by 3°C, while floor heating systems increased temperatures by 7°C, ensuring a consistent range of 21- 25°C by providing a range at defined indoor temperature values. Maximum loads are determined as 12.9W/m2 for cooling and 39.6W/m2 for heating. iii) The air change effectivenesses of different ventilation conditions are analysed. Four additional fans improved air exchange quality and decreased the volumetric mean age of air (AoA) from 1230 to 525 seconds. It is indicated that, while additional fans may decrease the mean AoA, maximizing the fan operation capacities is not obligatory to achieve increased air change effectiveness. Besides, the analysis of various fan operation scenarios significantly improves indoor environment conditions and energy efficiency. This thesis emphasizes the importance of design parameters in influencing indoor environmental conditions and energy consumption. The investigation of thermal air mixing and conditioning strategies underscores the need for a combined experimental and numerical approach. The findings contribute to effective solutions for warehouses storing temperature-sensitive products, ensuring optimal storage conditions and mitigating temperature variations during logistics operations.Doctoral Thesis Parametric Flow Simulation for Early Design Phase: Case Study of an Urban Regeneration Area in Izmir(Izmir Institute of Technology, 2022) Öner, Efe; Başaran, TahsinClimate change and its effects on the planning of cities require new dynamics for designing new expansion zones or neighborhood development projects. In conceptual phases, decision-makers, architects, planners, and engineers must consider extreme weather events and increased wind speeds in cities due to climate change to ensure the safety of pedestrians. Proposed building layouts, geometrical parameters, and features should be investigated in an artificial environment to satisfy wind behavior for acceptable conditions. Computational Fluid Dynamics (CFD) software provides insight into wind effects on the pedestrian level for the proposed layout of buildings and the surrounding area. This insight can boost the design process without conducting experimental wind tunnel tests. This study aims to assess the impact of building geometry (height, width, length) and building spacings in urban development projects for the safety and comfort of users in pedestrian-level wind environments with CFD simulations. The case area of this study is the first phase of an urban regeneration area in Izmir. The proposed layout is analyzed with prevailing wind speeds and directions to identify the dangerous and comfortable regions around buildings. Sub-configurations of buildings are simulated in CFD software to compare with existing wind tunnel tests for verification and validation. A design proposal with building features is evaluated with validated CFD parameters to examine the impact on pedestrian-level wind speeds. Mean speeds for corresponding comfort and safety limits of categorized human activities are compared to findings to identify suitable locations for these activities around buildings. Design parameters of urban layout; distance between buildings, height, and balconies on facades showed significant effects on pedestrian level wind environment. Building height among these parameters proved to be a decisive feature that should be considered in the early design stages.Doctoral Thesis Experimental and Numerical Investigation of a Heat Recovery Ventilation Unit With Phase Change Material for Building Facades(Izmir Institute of Technology, 2021) Pekdoğan, Tuğçe; Başaran, Tahsin; Tokuç, AyçaThis thesis presents a wall-integrated HRV unit design that stores latent heat thermal energy (LHTES). The system’s performance is tracked through experimental and numerical studies. The experimental tests of the unit took place in a controlled environment, where two HRV units are inside two wall-integrated ducts. The wall divides two conditioned spaces that represent indoors and outdoors. In one set of experiments, the commercially available system that stores sensible heat thermal energy (SHTES) with ceramic block. On another set of experiments, the newly designed LHTES system with the staggered tube bundle that contains phase change material (PCM). SHTES system shows the best performance in 2-minute, supply efficiency is 82% and exhaust efficiency is 67%. LHTES system shows the best performance in 20-minute and supply efficiency is 55% and exhaust efficiency is 30%. Numerical parametric studies on the HRV systems use the commercial CFD software ANSYS-FLUENT. These studies include the detailed flow and heat transfer analyses and the optimum operating times for two systems. As a result of these studies, the CFD results show good agreement with the experimental results. At the end of the thesis, the ability to increase the capacity of the HRV unit with PCM was investigated. In addition, the simulations for different climatic data were studied. According to the results, 12mm longitudinal, 12mm transverse pitch size for the ∅4.76mm tube is the most efficient system with total heat capacity of 45.77kJ. In addition, for different climates simulations, LHTES unit can be used throughout the year in Singapore.Doctoral Thesis Thermal Retrofitting on Traditional Building With Exterior Hall (sofa): Urban and Rural Houses of Muğla(Izmir Institute of Technology, 2019) Timur, Barış Ali; İpekoğlu, Başak; Başaran, TahsinSustaining functional continuity of historical buildings is a commonly acknowledged conservation strategy and thermal retrofitting interventions applied on these buildings has complemental potentials to this strategy as these interventions can be designed to increase the thermal satisfaction of occupants. The aim of this thesis is to examine the thermal behavior of a common historical building type in Anatolia, the traditional houses with exterior hall, and to determine enhancement potentials of possible thermal interventions which will not cause loss of heritage values. Method of the study consists of on-site thermal measurements and transient thermal analysis of case studies utilizing the software DesignBuilder. Case studies were selected from both urban and rural sub-settlements of Muğla City in order to detect possible effects of prevailing microclimates. With the results obtained, it was demonstrated the retrofitting interventions of thermal insulation works in roofs and floors between storeys, airtightness measures, addition of secondary glazing to window frames and the addition of closed circulation corridors provide significant improvements in thermal performance of the cases. According to simulation analyses, it was specified that these interventions would save 38.0% of the total building energy use in the urban and 49.4% in the rural subsettlements. These improvement percentages can even be increased to more than 80% when the integration of a new HVAC system such as ground-source heat pump is implemented. Consequently, it was determined the traditional houses with exterior hall have significant potentials for thermal enhancements which renders the application of thermal interventions as a capable conservation strategy.Doctoral Thesis Experimental and Numerical Analysis of Flow and Heat Transfer in Double Skin Facade Cavities(İzmir Institute of Technology, 2016) İnan, Tuğba; Başaran, TahsinIn this study, airflow and heat transfer in a double skin facade (DSF) cavity were examined numerically and experimentally under natural and forced flow conditions. An experimental setup was constructed i the laboratory environment. Experiments were performed for two different DSF's airflow modes; buffer zone and external air channel. These experiments vere conducted with and without a solarsimulator integratrd t the system. Furthermore, the effect of pressure drop elements in the cavity of DSF were analyzed experimentally. After the numerical results (CFD and nodal network) were verified with experimental measurements, dimensionless heat transfer correlations were developed for the natural and forced convections. As a result, an extensive experimental data set was obtained for different working conditions of DSF. So, the dimensionless pressure loss coefficients were calculated experimentally based on the geometric configuration of the pressure drop elements in the cavity. In natural convection, with Rayleigh numbers ranging from 8.59*109 to 1.41*1010 and the increasing tendency of the average Nusselt numbers from 142.6 to 168.8 were shown. A correlation for a cavity characteristic length of 0.116 was constructed to evaluate the heat flux. In forced convection, another dimensionless correlations weredeveloped to predict the heat transfer by using. Nusselt numbers with in the Reynolds numbers ranging from 28000 to 56000 for a DSF with an external airflow mode. These correlations could be used for different characteristic length ranged betwen 0.1 and 0.16. These correlations were used for the energy performence of DSF applications for different directions and climatic zones in Turkey and compared with the single skin facede.