The Effect of Corrosion by Steam at 1100–1500 F Upon the Heat Transfer Through Superheater Tube Alloys

1962 ◽  
Vol 84 (3) ◽  
pp. 289-294 ◽  
Author(s):  
H. L. Solberg ◽  
J. E. Brock ◽  
W. J. Rebello
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchangers ◽  
Superheater Tube ◽  
Austenitic Alloys ◽  
Inner Surface ◽  
In Series ◽  
High Temperature Steam ◽  
Tubular Specimens

Heat-transfer tests were made on tubular specimens of ferritic and austenitic types of superheater alloys which had been exposed to high-temperature steam for periods of 6, 12, or 18 months for the purpose of determining the effect of corrosion by steam. Specimens of scaled tubes and new tubes of the same alloy were machined externally to the same dimensions and surfaces, were mounted in similar heat exchangers, and were tested in series under such conditions that the only difference was in the scaled inner surface of the corroded tube and the bright, smooth, honed inner surface of the clean tube. The heat transfer through ferritic tubes was reduced by as much as fifteen per cent for the temperatures and exposure periods reported upon. The thin, dense scale on the austenitic alloys increased the heat transfer over that of the clean tube by as much as eight per cent, probably because of the increased roughness of the corroded surface.

Scaling Behavior of Superheater Tube Alloys in ASME High Temperature Steam Research Tests at 1100–1500 F

1962 ◽  
Vol 84 (3) ◽  
pp. 223-257 ◽  
Author(s):  
F. Eberle ◽  
C. H. Anderson
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Scaling Behavior ◽  
Effect Of Temperature ◽  
Relative Resistance ◽  
Superheater Tube ◽  
Shock Resistance ◽  
High Temperature Steam

The scales formed on seven ferritic and ten austenitic types of commercial tubing presently in use and of potential future use for superheater service were examined after 6, 12, and 18 months’ exposure to air and to flowing steam of 2000 psi at temperatures of 1100, 1200, 1350, and 1500 F. The effect of temperature and time of exposure on the adherence, thermal-shock resistance, thickness, structure, and chemical composition of the scales was investigated and the relative resistance to scaling of the various alloys evaluated.

Performance Optimization of Compact Ceramic High Temperature Heat Exchangers

2007 ◽  
Author(s):  
Q. Y. Chen ◽  
M. Zeng ◽  
D. H. Zhang ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Performance Optimization ◽  
Heat Exchangers ◽  
Radiation Heat Transfer ◽  
Surface Radiation ◽  
Radiation Heat ◽  
High Temperature Side ◽  
Temperature Heat

In the present paper, the compact ceramic high temperature heat exchangers with parallel offset strip fins and inclined strip fins (inclined angle β = 0∼70°) are investigated with CFD method. The numerical simulations are carried out for high temperature (1500°C), without and with radiation heat transfer, and the periodic boundary is used in transverse direction. The fluid of high temperature side is the standard flue gas. The material of heat exchanger is SiC. NuS-G.R(with surface and gaseous radiation heat transfer) is averagely higher than NuNo.R (without radiation heat transfer) by 7% and fS-G.R is averagely higher than fNo.R by 5%. NuS-G.R(with surface and gaseous radiation heat transfer) is averagely higher than NuS.R (with only surface radiation heat transfer) by 0.8% and fS-G.R is averagely higher than fS.R by 3%. The thermal properties have significantly influence on the heat transfer and pressure drop characteristics, respectively. The heat transfer performance of the ceramic heat exchanger with inclined fins (β = 30°) is the best.

Development of a high-temperature ceramic to metal seal

1997 ◽  
Vol 211 (2) ◽  
pp. 109-114 ◽  
Author(s):  
S B M Beck ◽  
P R Langston ◽  
B C R Ewan ◽  
P E Messer ◽  
R Smyth ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchangers ◽  
Axial Stress ◽  
Tube Sheet ◽  
Combustion Gas ◽  
Large Pressure ◽  
Metal Seal ◽  
Process Fluid ◽  
Set Up

Research is currently being conducted into the construction of high-temperature (>1000°C) tubular heat exchangers that are to operate with a large pressure differential between low-pressure combustion gas and a process fluid. High operating temperatures preclude the use of metals. Therefore it is necessary to use ceramic heat transfer components and to insulate other components to counteract the direct heat. As the high-temperature ceramic heat transfer tubes exhibit a variable thermal expansion relative to the outer metallic casing and tube sheet, it is necessary for the seals to slide. This prevents excessive axial stress being set up in the ceramic tubes, thus prolonging their life.

Transient Modeling of Advanced High Temperature Reactor (AHTR) in RELAP5/SCDAPSIM/MOD 4.0

2018 ◽  
Author(s):  
Hsun-Chia Lin ◽  
Sheng Zhang ◽  
Shanbin Shi ◽  
Xiaodong Sun ◽  
Richard Christensen
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchangers ◽  
Ambient Air ◽  
Normal Operation ◽  
Forced Circulation ◽  
Oak Ridge ◽  
Decay Heat ◽  
High Temperature Reactor ◽  
Relap5 Code

The Advanced High Temperature Reactor (AHTR) is a fluoride-salt-cooled high-temperature reactor (FHR) design concept that is currently being developed at Oak Ridge National Laboratory for efficient production of electricity with improved safety features. Transient analyses of different scenarios are critical to demonstrate the safety of the AHTR design. An AHTR reactor model has been developed using RELAP5/SCDAPSIM/MOD 4.0. Thermodynamic and transport properties of three molten fluoride salts, namely FLiBe, FLiNaK, and KF-ZrF4, have been implemented into the RELAP5 code. The AHTR RELAP5 model consists of a reactor core, an upper plenum, a lower plenum, three primary loops, and three Direct Reactor Auxiliary Cooling Systems (DRACS) loops. DRACS Heat Exchangers (DHX) and Natural Draft Heat Exchangers (NDHX) are important components of DRACS and provide coupling between the primary loops and DRACS loops, and DRACS loops and air chimneys, respectively. Single-wall fluted tube heat exchanger designs have been proposed for the DHX and the NDHX to improve heat transfer performance in the two heat exchangers, and heat transfer correlations for fluted tubes have also been implemented into the RELAP5 code. In this study, steady-state reactor normal operation and two transient scenarios are analyzed with the RELAP5 AHTR model. Based on a thermal hydraulics Phenomena Identification Ranking Table (PIRT) exercise, loss of forced circulation (LOFC) and loss of multiple DRACS loops are selected as the two transients for analysis. During transients, the decay heat is removed by the ambient air, fully relying on natural circulation/convection. The results of both transient scenarios show sufficient decay heat removal capabilities of DRACS with the proposed design.

Sign in / Sign up

Export Citation Format

Share Document