Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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COAR Access Rights: search.filters.coarAccessRights.open accessSubject: search.filters.subject.Plate heat exchanger

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  • Master Thesis
    The Development of Forming Simulation Methodology of a Plate Type Heat Exchanger
    (01. Izmir Institute of Technology, 2023) Şimşek, İbrahim; Taşdemirci, Alper
    In this study, the production process of plate type heat exchangers was developed as a simulation methodology. Within the scope of the study, first, the parameters in the production process were determined. Then, mechanical characterization studies were planned with the AISI 316L stainless steel material used during production and the alternative AISI 304 stainless steel material, and the tests were completed with the support of the relevant stakeholders. The tests were determined according to the requirements of the simulation methodology. In this context, uniaxial tensile test, biaxial hydraulic bulge test and Split Hopkinson tensile tests were performed to obtain the necessary inputs for the mechanical characterization of the material and creating the material model. The material models established with the information obtained from the tests were validated with the modeling of the test setups in the numerical environment. The simulation methodology was developed in the LS-DYNA environment in the light of the process parameters obtained from the production and the data obtained from the mechanical characterization tests. The simulation model created with the developed methodology was verified because of comparison with the sample produced from AISI 316L stainless steel material taken from production. After the verified model was obtained, a simulation model was created with AISI 304 stainless steel. In addition, for the model formed with AISI 316L stainless steel, process parameters optimization study was carried out, and preliminary work activities related to reducing production times were carried out in numerical environment. After these modeling activities, the knowledge of the license plate was increased. In addition, effective plastic stress during the process, springback effect, residual stress values after springback, effective plastic strain, thickness distribution and thickness reduction values were obtained for the plate. By using the forming limit diagram of AISI 316L stainless steel, information about the final formability behavior was obtained.
  • Master Thesis
    Investigation of the Fatigue Behaviour of Metallic Components Used in Plate Heat Exchangers Under Variable Dynamic Loads
    (Izmir Institute of Technology, 2020) Hayta, Yiğit; Kandemir, Sinan; Kandemir, Sinan
    Plate heat exchanger (PHE) is a component that provides heat to be transferred from hot water to domestic cold water without mixing of them with a high efficiency. Over the lifetime of the PHE, cyclic pressures act on the brazing points and the plates, and this may lead to fatigue failure. The fatigue behaviours of the PHEs which are designed by using copper brazed 316L and 304L stainless steels, were investigated in this thesis by performing strain based fatigue tests to also seek the feasibility of the use of 304L stainless steel in PHE production to reduce the cost. Besides, the microstructural investigation of the brazed regions was conducted and, the tensile tests for both non-brazed and brazed steel specimens were performed in order to determine the mechanical properties of the samples. The fatigue tests were carried out with twelve specimens for each sample groups at four different load levels as displacement (strain) controlled with a stress ratio of R=0 and 5 Hz frequency. Finite Element Analysis (FEA) was performed to determine the strain distribution on the plates of PHEs during their operation to estimate the lifetime of PHEs by using the generated lifetime curves based on the fatigue tests. Consequently, it was obtained that the ultimate tensile strength and fracture strain of non-brazed steel specimens are higher than those of the brazed specimens. The Scanning Electron Microscopy (SEM) analysis shows that; copper can diffuse into 316L easier than 304L and the use of copper foil with 50 µm thickness results in more defect at brazing regions compared to 100 µm thickness. Hereunder the fatigue test results, Weibull Analysis was performed and the fatigue life curves were generated. It was found that 316L brazed joint has approximately 33 times greater fatigue life than 304L brazed joint and filler metal thickness is more likely to have a linear relationship with fatigue life. Finally, fatigue lives of each sample group were calculated based on the loads determined by FEA. The results suggest that either 316L or 304L stainless steels can be used as PHE material as both materials satisfy the lifetime requirement of 15 years which was preliminarily defined by Bosch Thermotechnology (TT).