scholarly journals Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4711
Author(s):  
Armanto P. Simanjuntak ◽  
Jae-Young Lee
Keyword(s):  
Heat Exchanger ◽  
Stress Intensity ◽  
Maximum Stress ◽  
High Stress ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Printed Circuit ◽  
Mechanical Integrity ◽  
Finite Element Analysis Simulation ◽  
Maximum Stress Intensity

Printed circuit heat exchangers (PCHEs) are often subject to high pressure and temperature difference between the hot and cold channels which may cause a mechanical integrity problem. A conventional plate heat exchanger where the channel geometries are semi-circular and etched at one side of the stacked plate is a common design in the market. However, the sharp edge tip channel may cause high stress intensity. Double-faced type PCHE appears with the promising ability to reduce the stress intensity and stress concentration factor. Finite element analysis simulation has been conducted to observe the mechanical integrity of double-etched printed circuit heat exchanger design. The application of an additional ellipse upper channel helps the stress intensity decrease in the proposed PCHE channel. Five different cases were simulated in this study. The simulation shows that the stress intensity was reduced up to 24% with the increase in additional elliptical channel radius. Besides that, the horizontal offset channels configuration was also investigated in this study. Simulation results show that the maximum stress intensity of 2.5 mm offset configuration is 9% lower compared to the maximum stress intensity of 0 mm offset. This work proposed an additional elliptical upper channel with a 2.5 mm offset configuration as an optimum design.

Structural Integrity Assessment of a Unit Cell in a Laboratory-Scale Printed Circuit Heat Exchanger for Molten Salt Reactors With Supercritical CO2 Power Cycle

2021 ◽  
Author(s):  
Shuai Che ◽  
Sheng Zhang ◽  
Adam Burak ◽  
Xiaodong Sun
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Stress Intensity ◽  
Molten Salt ◽  
Maximum Stress ◽  
Structural Integrity ◽  
Unit Cell ◽  
Laboratory Scale ◽  
Printed Circuit ◽  
Maximum Stress Intensity

Abstract The Printed Circuit Heat Exchanger (PCHE) is considered promising as an intermediate heat exchanger for Molten Salt Reactors (MSRs) due to its highly compact construction, high heat transfer effectiveness, and capability of withstanding high pressures. In this study, thermal-mechanical simulations were performed using a two-channel unit-cell model with the attempt to investigate the structural integrity of a laboratory-scale PCHE that was designed for molten salt-to-supercritical carbon dioxide heat transfer, with the temperature field obtained from Computational Fluid Dynamics (CFD) simulations. It is shown that the fillets on the semi-circular channel walls are stress concentration regions and that the stress intensity decreases quickly as the distance from the fillets increases. A quick drop in the maximum stress intensity is observed with the increase of the fillet radius. There is no significant increase in the stress intensity for locations around the zigzag sharp corners. With a lower bulk temperature and a higher stress intensity, the region close to the outlet of the PCHE hot channels is more vulnerable to potential failures than the inlet region of the hot channels. In addition, the choice of channel models has a weak impact on the maximum stress intensity around the cold channel fillets.

Elastic Thermal Stresses in Bimetallic Pipe Welds

1980 ◽  
Vol 102 (4) ◽  
pp. 430-432 ◽  
Author(s):  
R. D. Blevins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Maximum Stress ◽  
Thermal Stresses ◽  
Simple Expression ◽  
Element Analysis ◽  
Maximum Stress Intensity ◽  
Bimetallic Pipe ◽  
Uniform Change

The elastic thermal stresses in a welded transition between two pipes of the same size but different alloys are explored. A stress-free temperature is postulated and the stress due to a uniform change in temperature is characterized by the maximum stress intensity in the weld. A simple expression for predicting this maximum stress intensity is developed based on the results of finite element analysis.

Finite Element Stress Analysis of Intersection Region of Nozzle and Blind Flange

2012 ◽  
Vol 605-607 ◽  
pp. 1307-1310
Author(s):  
Jun Hua Dong ◽  
Bing Jun Gao
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Analysis ◽  
Maximum Stress ◽  
Stress Variation ◽  
Finite Element Stress Analysis ◽  
Maximum Stress Intensity ◽  
Variation Rule ◽  
Finite Element Stress

The stress analysis of the intersections region of nozzle & blind flange is implemented by means of FEA. The stress variation rule was obtained and the maximum Stress intensity is at the inside of intersections region of nozzle & blind flange. In accordance with JB4732-1995 (2005 Confirmed edition), the safety of structure was evaluated. The results show that the dimensiom given in the paper can meet the requirement for safety.

Finite Element Analysis for Nozzle With External Loads

2011 ◽  
Author(s):  
Hak-Sung Lee ◽  
Chang-Hoon Ha ◽  
Tae-Jung Park
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Pressure Vessel ◽  
Maximum Stress ◽  
Structural Integrity ◽  
Finite Element Models ◽  
Pressurized Water ◽  
Dimensional Finite Element ◽  
Maximum Stress Intensity ◽  
External Loads

Various kinds of nozzles are attached to a pressure vessel including Steam Generator (SG) in a pressurized water reactor plant. The downcomer feedwater nozzle on the upper vessel shell and the economizer feedwater nozzle in the lower vessel shell of the SG are representative nozzles which have a non axi-symmetric shape. In most cases, external loads composed with forces and moments are imposed on those nozzles during the plant operation. In order to evaluate structural integrity of junctures between the nozzles and vessels in compliance with the ASME Boiler and Pressure Vessel Code, Section III, it is essential to find the maximum stress intensity resulting from those loads. Welding Research Council (WRC) Bulletin 297 has been used to find the maximum stress intensity since it is not straightforward to calculate the stress intensity with a non axi-symmetric two dimensional finite element model. However, the compatibility of adopting WRC Bulletin 297 to nozzles which have a variety of geometries shall be considered. Moreover, the applicability of the stress intensity resulting from the bulletin should be into consideration when interested lines where stress intensity linearization is to be performed are not exactly consistent with the line defined in the Bulletin. In this study, the nozzles in cylindrical vessel shells are developed as three dimensional finite element models, which are loaded with unit forces and moments. The stress intensities from finite element models are investigated through a comparison of WRC Bulletin 297. In addition, a methodology to apply the stress intensity results from WRC 297 to different lines is proposed.

Observation of Crack Growth Behavior of Various Cracks in 4.762mm Diameter Silicon Nitride Balls under Cyclic Compressive Load

2019 ◽  
Vol 971 ◽  
pp. 101-105
Author(s):  
Takumi Toriki ◽  
Tomoya Matsui ◽  
Katsuyuki Kida
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Silicon Nitride ◽  
Intensity Factor ◽  
Maximum Stress ◽  
Compressive Load ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Maximum Stress Intensity ◽  
Maximum Stress Intensity Factor

In order to investigate the effect of pre-crack lengths on strength of silicon nitride balls under cyclic pressure loads, growth behavior of 600~700μm pre-cracks were compared to those of 200μm~300μm and 400~500μm pre-cracks. Furthermore, the change in initial threshold limit of the maximum stress intensity factor was discussed. It was found that the increasing ratio of stress intensity factor during N=0 and N=1000 distinguished the failure and non-failure, and pre-crack length had strong effect on the threshold limits of the increasing ratio.

Stress Distribution in a Rotating Spherical Shell of Arbitrary Thickness

1961 ◽  
Vol 28 (1) ◽  
pp. 127-131 ◽  
Author(s):  
M. A. Goldberg ◽  
V. L. Salerno ◽  
M. A. Sadowsky
Keyword(s):  
Exact Solution ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Spherical Shell ◽  
Maximum Stress ◽  
Elastic Spherical Shell ◽  
Arbitrary Thickness ◽  
Maximum Stress Intensity ◽  
Thickness Parameter

This paper contains an exact solution for the stress distribution in an elastic spherical shell rotating about a diametral axis. The surfaces of the shell are free of boundary tractions. The coefficients necessary to determine the stresses at any point have been calculated for eight values of a thickness parameter, α. Graphs of the maximum stress intensity as a function of α are presented.

The Role of Fluid Dynamics in Distributing Ankle Stresses in Anatomic and Injured States

2016 ◽  
Vol 37 (12) ◽  
pp. 1343-1349 ◽  
Author(s):  
Kamran S. Hamid ◽  
Aaron T. Scott ◽  
Benedict U. Nwachukwu ◽  
Kerry A. Danelson
Keyword(s):  
Finite Element ◽  
Synovial Fluid ◽  
Principal Stress ◽  
Maximum Stress ◽  
High Stress ◽  
Distal Tibia ◽  
Element Model ◽  
Maximum Principal Stress ◽  
Ankle Injuries ◽  
Element Analysis

Background: In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in maximum principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesized that synovial fluid could be a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states. Methods: As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test configurations were investigated using a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous 2 bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium–owned GHBMC model, M50 version 4.2, a model of an average-sized male (distributed by Elemance, LLC, Winston-Salem, NC). The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight, and the maximum principal stress was computed. Results: All numerical simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula, and talus reduced the maximum principal stress computed in the distal tibia at maximum load from 31.3 N/mm2 to 11.5 N/mm2. Following 1 mm lateral translation of the talus and fibula, there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated into the model. Conclusions: The findings in this study demonstrate a meaningful role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid was less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the tibia and should be accounted for in future experiments. Clinical Relevance: Synovial fluid may play a protective role in ankle injuries, thus delaying the onset of arthritis. Reactive joint effusions may also function to additionally redistribute stresses with higher volumes of viscous fluid.

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