Thermo-Mechanical Deformation in Heat Sink Seal Rings

2005 ◽  
Author(s):  
Lyndon Scott Stephens ◽  
Matthew A. Hayden
Keyword(s):  
Heat Exchanger ◽  
Heat Sink ◽  
Thermal Deformation ◽  
Point Contact ◽  
Mechanical Deformation ◽  
Outer Diameter ◽  
Seal Ring ◽  
Contact Pattern ◽  
Mechanical Seals ◽  
Interface Contact

Heat sink mechanical seals use a heat exchanger built directly into the stationary seal ring to control the temperature at the seal interface. This paper presents the latest analytical and experimental results showing the thermal deformation of the heat sink seal at the sealing interface. The results show that the virgin interface contact pattern (before wear) is non-conformally convex with point contact towards the outer diameter. These results are discussed in relation to positive and negative coning that is found in conventional seal rings.

Analysis of Mechanical Seal Behavior During Transient Operation

1998 ◽  
Vol 120 (2) ◽  
pp. 191-197 ◽  
Author(s):  
S. R. Harp ◽  
R. F. Salant
Keyword(s):  
Thermal Deformation ◽  
Transient Behavior ◽  
Mechanical Deformation ◽  
Contact Forces ◽  
Squeeze Film ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Pressure Distributions ◽  
Deformation Mechanics ◽  
Gas Seals

A mathematical model that predicts the transient behavior of gas or liquid lubricated hydrostatic mechanical seals has been developed. The analysis includes an evaluation of the fluid, contact, and deformation mechanics of a mechanical seal subject to constant or varying rotational speed and sealed pressure. Squeeze film effects are included. For gas seals, slip at the walls is also taken into account. Results include predictions of film thickness distributions, contact forces, leakage rates, pressure distributions, heat generation rates, thermal deformation, and mechanical deformation.

scholarly journals Fatigue Variability of Alloy 625 Thin-Tube Brazed Specimens

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1162
Author(s):  
Seulbi Lee ◽  
Hanjong Kim ◽  
Seonghun Park ◽  
Yoon Suk Choi
Keyword(s):  
Fatigue Life ◽  
Heat Exchanger ◽  
Room Temperature ◽  
Metal Layer ◽  
Outer Diameter ◽  
Multiple Crack ◽  
Joint Failure ◽  
Alloy 625 ◽  
Thin Tube ◽  
Brazed Joint

As an advanced heat exchanger for aero-turbine applications, a tubular-type heat exchanger was developed. To ensure the optimum performance of the heat exchanger, it is necessary to assess the structural integrity of the tubes, considering the assembly processes such as brazing. In this study, fatigue tests at room temperature and 1000 K were performed for 0.135 mm-thick alloy 625 tubes (outer diameter of 1.5 mm), which were brazed to the grip of the fatigue specimen. The variability in fatigue life was investigated by analyzing the locations of the fatigue failure, fracture surfaces, and microstructures of the brazed joint and tube. At room temperature, the specimens failed near the brazed joint for high σmax values, while both brazed joint failure and tube side failure were observed for low σmax values. The largest variability in fatigue life under the same test conditions was found when one specimen failed in the brazed joint, while the other specimen failed in the middle of the tube. The specimen with brazed joint failure showed multiple crack initiations circumferentially near the surface of the filler metal layer and growth of cracks in the tube, resulting in a short fatigue life. At 1000 K, all the specimens exhibited failure in the middle of the tube. In this case, the short-life specimen showed crack initiation and growth along the grains with large through thickness in addition to multiple crack initiations at the carbides inside the tube. The results suggest that the variability in the fatigue life of the alloy 625 thin-tube brazed specimen is affected by the presence of the brazed joint, as well as the spatial distribution of the grain size and carbides.

Prediction and Performance of Compact Latent Heat Recovery Heat Exchanger With Small Diameter Tubes

2007 ◽  
Author(s):  
Masahiro Osakabe
Keyword(s):  
Heat Exchanger ◽  
Power System ◽  
Latent Heat ◽  
Heat Recovery ◽  
Small Diameter ◽  
Cooling Water ◽  
Prediction Method ◽  
Outer Diameter ◽  
Exhaust Gas ◽  
And Performance

The most part of energy losses in power system such as fuel cells is due to the heat released by the exhaust gas to atmosphere. The exhaust gas consists of non-condensable gas and steam with sensible and latent heat. As a lot of latent heat is included in the exhaust gas, its recovery is very important to improve the power system efficiency. Based on the previous basic studies, a thermal hydraulic prediction method for latent heat recovery exchangers was proposed. For the condensation of steam on heat transfer tubes, the modified Sherwood number taking account of the mass absorption effect on the wall was used. Two kinds of compact heat exchanger with staggered banks of bare tubes of 10.5 or 4mm in outer diameter was designed with the prediction method. The more compactness was obtained with the smaller tubes at a designed heat recovery. The thermal hydraulic behavior in the compact heat exchangers was experimentally studied with air-steam mixture gas. In the parametric experiments varying the steam mass concentration, the temperature distributions of cooling water and mixture gas were measured. The experimental results agreed well with the prediction proposed in this study and the more compactness with the smaller tubes was proved.

Geometrical optimization of bare tube heat exchangers for process industries

2005 ◽  
Vol 219 (2) ◽  
pp. 139-147
Author(s):  
T. Q. Ma ◽  
K. T. Ooi ◽  
T. N. Wong
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Optimization Design ◽  
Design Method ◽  
Outer Diameter ◽  
Process Industries ◽  
Performance Improvements ◽  
Geometrical Optimization ◽  
Simulation Results ◽  
Bare Tube

This paper presents simulation results on the geometrical optimization design of bare tube heat exchangers. By linking a mathematical model with an optimization alogorithm, it is possible to predict which combination of five geometrical variables would produce a given coil capacity of a heat exchanger, the minimum core volume size operating at the minimum pressure drop. A constrained multivariable direct search technique is used in which the five geometrical variables and a mixture of five explicit and implicit constraints are accommodated. Using this design method, three typical sizes of bare tube optimization cases have been studied. The simulation results predict significant performance improvements for heat exchanger design. The range of tube outer diameter in this optimization study is from 4.9 to 9.0 mm.

Optimum Design of Flat End Face Mechanical Seal Based on Coupling Analysis

2010 ◽  
Vol 37-38 ◽  
pp. 819-822 ◽  
Author(s):  
Jian Feng Zhou ◽  
Bo Qin Gu ◽  
Chun Lei Shao
Keyword(s):  
Optimum Design ◽  
Thermal Deformation ◽  
Coupling Effect ◽  
Design Method ◽  
Fluid Film ◽  
Outer Side ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Friction Heat ◽  
Bearing Force

The flat end face mechanical seals are widely used in shaft sealing at moderate rotational speed. The thermal deformation of the rotating and stationary rings initiated by friction heat of fluid film should be primarily considered in the design of mechanical seal. In consideration of the coupling effect among the thermal deformation of sealing rings, the fluid flow in the gap composed by end faces of sealing rings and the heat transfer from fluid film to sealing rings, the optimum design method for flat end face mechanical seal is established. The end faces are fabricated to form a divergent gap at the inner side of the sealing rings, and a convergent gap will occur at the outer side and a parallel gap will be obtained at where the original divergent gap is due to the thermal deformation. After optimization, the leakage rate can be reduced while the bearing force of fluid film is still large enough to keep the fluid lubrication of the end faces.

Non-Condensable Gases Effect on Heat Transfer Processes Between Condensing Steam and Boiling Water in Heat Exchanger With Multirow Horizontal Tube Bundle

2010 ◽  
Author(s):  
A. V. Morozov ◽  
O. V. Remizov ◽  
A. A. Tsyganok
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Tube Bundle ◽  
Horizontal Tube ◽  
Boiling Water ◽  
Test Facility ◽  
Primary Circuit ◽  
Outer Diameter ◽  
Steam Condensation ◽  
Experimental Heat

The experimental investigations of non-condensable gases effect on the steam condensation inside multirow horizontal tube bundle of heat exchanger under heat transfer to boiling water were carried out at the large-scale test facility in the Institute for Physics and Power Engineering (IPPE). The experiments were carried out for natural circulation conditions in primary and secondary circuits of the facility at primary circuit steam pressure of Ps1 = 0.34 MPa. The experimental heat exchanger’s tube bundle consists of 248 horizontal coiled tubes arranged in 62 rows. Each row consists of 4 stainless steel tubes of 16 mm in outer diameter, 1.5 mm in wall thickness and of 10.2 m in length. The experimental heat exchanger was equipped with more than 100 thermocouples enabling the temperatures of primary and secondary facility circuits to be controlled in both tube bundle and in the inter-tubular space. The non-condensable gases with different density — nitrogen and helium were used in the experiments. The volumetric content of gases in tube bundle amounted to ε = 0.49. The empirical correlation for the prediction of the relative heat transfer coefficient k/k0 = f (ε) for steam condensation in steam-gas mixture was obtained.

High Temperature Design and Damage Evaluation of Mod.9Cr-1Mo Steel Heat Exchanger

2011 ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Jong-Bum Kim ◽  
Jae-Hyuk Eoh ◽  
Yong-Bum Lee ◽  
Hong-Yune Park
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Fatigue Damage ◽  
Effective Length ◽  
Outer Diameter ◽  
Element Analysis ◽  
Test Loop ◽  
Creep Fatigue ◽  
Shell And Tube ◽  
Critical Locations

High temperature design and evaluation of creep-fatigue damage for sodium-sodium heat exchanger, DHX (Decay heat exchanger) in a sodium test loop have been conducted. The DHX is a shell- and tube-type heat exchanger with outer diameter of 21.7mm, thickness of 1.65mm and effective length of 1.73m. The DHX shell and tube materials were Mod.9Cr-1Mo steel. The temperatures of shell inlet and shell outlet in the DHX are 510°C and 308°C, respectively, while the temperatures of tube inlet and outlet are 254°C and 475°C, respectively. Three dimensional finite element analysis was conducted for the DHX and evaluation of creep-fatigue damage at several critical locations of the heat exchanger was carried out according to the elevated temperature design codes of the ASME Section III Subsection NH and RCC-MR. Evaluations on the integrity of the DHX and code comparisons were carried out for the critical locations of the DHX.

Analysis of Heat Transfer Enhancement in Minichannel Heat Sinks With Turbulent Flow Using H2O–Al2O3 Nanofluids

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
T. L. Bergman
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Turbulent Flow ◽  
Heat Transfer Enhancement ◽  
Thermophysical Properties ◽  
Heat Sink ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Electronic Heat ◽  
Limited Usefulness

Heat transfer enhancement associated with use of a nanofluid coolant is analyzed for small electronic heat sinks. The analysis is based on the ε-NTU heat exchanger methodology, and is used to examine enhancement associated with use of H2O–Al2O3 nanofluids in a heat sink experiencing turbulent flow. Predictive correlations are generated to ascertain the degree of enhancement based on the fluid’s thermophysical properties. The enhancement is quite small, suggesting the limited usefulness of nanofluids in this particular application.

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