Fabrication and formability evaluation of thick-wall chromized and coextruded superheater tubings for advanced cycle power applications

Flanged and flued type expansion joint (thick wall expansion bellow) used as an integral part of many shell and tube heat exchanger where process conditions produce differential expansion between shell and tubes. It provides flexibility for thermal expansion and also functions as a pressure retaining part. Design of expansion joints is usually based on trial and error method in which initial geometry must be assumed, and accordingly maximum stresses and spring rate are be calculated. Inadequate selection of geometry leads to higher tubesheet and bellow thickness, which increases cost of equipment. This paper presents standardization and optimum design approach of flange and flued expansion bellow fulfilling ASME VIII-1 and TEMA standard requirement. Methodology to define expansion bellow geometry is developed, and geometry dimensions are tabulated for expansion bellow diameter from 300 to 2000 mm and thickness from 6 to 30 mm. Each defined geometry is analyzed using finite element method, and maximum von Mises stresses are calculated for bellow axial displacement from 0.5 to 1.5 mm and internal pressure from 0.1 to 6.5 MPa. Spring rate is also calculated for each defined geometry for consideration in tubesheet calculation. Accordingly, optimum design methodology is developed, tested, and compared with existing design. Results depicted that proposed standardization approach and design methodology will optimize expansion bellow and tubesheet thickness and will also save considerable time in finalization of heat exchanger design.

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MICROSTRUCTURE ANALYSIS OF MOSO BAMBOO (Phyllostachys pubescens MAZEL) SURFACE AFTER UV RADIATION

Surface Review and Letters ◽

10.1142/s0218625x19500902 ◽

2019 ◽

Vol 27 (01) ◽

pp. 1950090

Author(s):

HAIXIA YU ◽

XIN PAN ◽

WEIMING YANG ◽

WENFU ZHANG ◽

XIAOWEI ZHUANG

Keyword(s):

Uv Radiation ◽

Cell Walls ◽

Uv Light ◽

Parenchyma Cell ◽

Moso Bamboo ◽

Thick Wall ◽

Phyllostachys Pubescens ◽

Thin Wall ◽

Intercellular Spaces ◽

Parenchyma Cell Walls

Bamboo material is widely used in outdoor applications. However, they are easily degraded when exposed to sunlight, their smooth surface will gradually turn to rough, and small cracks will appear and finally develop to large cracks. The paper presents a first-time investigation on the microstructure changes in the tangential section of Moso bamboo (Phyllostachys pubescens Mazel) radiated by artificial UV light. The results showed that the cracks mainly appeared at intercellular spaces of fibers where lignin content was high, the parenchyma cell walls and neighbor pits where the cell wall was very thin and more vulnerable than the other parts. In addition, the part of raised area and pit cavity tended to absorb more UV light radiation and showed more and larger cracks than the otherwhere. Cracks at the intercellular spaces of fibers were larger and bigger than those on the parenchyma cell walls. The cracks on the pits of the parenchyma cell walls normally appeared at one pit and then extended to the several surrounding pits. Bordered pits cavity showed more and larger cracks than the pits on the thin wall cells. The simple pits on the thick wall cells and the fiber cells were unaffected by UV radiation.

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The use of a solution of the inverse heat conduction problem to monitor thermal stresses

E3S Web of Conferences ◽

10.1051/e3sconf/201910801003 ◽

2019 ◽

Vol 108 ◽

pp. 01003

Author(s):

Jan Taler ◽

Piotr Dzierwa ◽

Magdalena Jaremkiewicz ◽

Dawid Taler ◽

Karol Kaczmarski ◽

...

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Power Plants ◽

Thermal Stresses ◽

Thermal Power ◽

Temperature Fields ◽

Thick Wall ◽

Fluid Temperature ◽

Unsteady Temperature

Thick-wall components of the thermal power unit limit maximum heating and cooling rates during start-up or shut-down of the unit. A method of monitoring the thermal stresses in thick-walled components of thermal power plants is presented. The time variations of the local heat transfer coefficient on the inner surface of the pressure component are determined based on the measurement of the wall temperature at one or six points respectively for one- and three-dimensional unsteady temperature fields in the component. The temperature sensors are located close to the internal surface of the component. A technique for measuring the fastchanging fluid temperature was developed. Thermal stresses in pressure components with complicated shapes can be computed using FEM (Finite Element Method) based on experimentally estimated fluid temperature and heat transfer coefficient

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Development of Semi-Solid Die Casting Product Design and Die Design Technology for Aluminium Alloy Clamp

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.256.334 ◽

2016 ◽

Vol 256 ◽

pp. 334-339 ◽

Cited By ~ 1

Author(s):

Song Chen ◽

Fan Zhang ◽

You Feng He ◽

Da Quan Li ◽

Qiang Zhu

Keyword(s):

Product Design ◽

Die Casting ◽

Casting Process ◽

Die Design ◽

Thick Wall ◽

Thin Wall ◽

Gating System ◽

Cross Sectional ◽

Die Casting Process ◽

Semi Solid

Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity makes product design and die design, such as gating system, overflow and venting system, be different between these two die casting processes. In the present paper, taking a clamp product as an example, analyses the product optimization and die design by comparing the experimental and computational numerical simulation results. For the clamp, product structure is designed to be suitable for characters of SSM die casting process. The gating system is designed to be uniform variation of thickness, making the cross-sectional area uniformly reduce from the biscuit to the gate. This design ensures semi-solid metal slurry to fill die cavity from thick wall to thin wall. Gate position is designed at the thickest location, the gate shape of semi-solid die casting is set to be much bigger than traditional liquid casting. A good filling behaviour can be achieved by aforementioned all these design principles and it will be helpful to the intensification of pressure feeding after filling.

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