Plakalı eşanjörlerde kullanılan metalik komponentlerin değişken dinamik yükler altında yorulma ...

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" Plakalı eşanjörlerde kullanılan metalik komponentlerin değişken dinamik yükler altında yorulma davranışının incelenmesi "
Hayta, Yiğit Kandemir, Sinan

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112269
Doc. No	:	TLpq2524176151
Main Entry	:	Hayta, Yiğit
	:	Kandemir, Sinan
Title & Author	:	Plakalı eşanjörlerde kullanılan metalik komponentlerin değişken dinamik yükler altında yorulma davranışının incelenmesi\ Hayta, YiğitKandemir, Sinan
College	:	Izmir Institute of Technology (Turkey)
Date	:	2020
student score	:	2020
Degree	:	Master's
Page No	:	106
Abstract	:	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).
Subject	:	Boilers
	:	Energy efficiency
	:	Heat exchangers
	:	Heat transfer
	:	Heating
	:	Metal fatigue