An Analytical Model to Predict Condensate Retention on Horizontal Integral-Fin Tubes

1985 ◽  
Vol 107 (2) ◽  
pp. 361-368 ◽  
Author(s):  
T. M. Rudy ◽  
R. L. Webb
Keyword(s):  
Analytical Model ◽  
Test Data ◽  
Liquid Retention ◽  
Fluid Properties ◽  
Fin Tube ◽  
Fin Tubes

In this paper, the authors develop a general analytical model to predict the amount of surface that is flooded during condensation on a horizontal, integral-fin tube. The model is based on capillary equations that predict the amount of liquid rise on a vertical u-shaped channel. The space between adjacent integral fins forms such a channel. The authors compare the model to test data taken during condensation on three integral-fin tubes (748-to-1378 fpm) and a range of fluid properties. The analytical model predicts the amount of liquid retention on a horizontal, integral-fin tube within ± 10 percent over most of the data. The analysis is performed for the case of negligible vapor shear.

Improvement of analytical model using uncertain test data

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 489-495
Author(s):  
Abdelkrim Cherki ◽  
Bertrand Lallemand ◽  
Thierry Tison ◽  
Pascal Level
Keyword(s):  
Analytical Model ◽  
Test Data

A New Transient Thermal Model for Predicting Cooling Temperature and Cooldown Time of a Subsea Pipe-in-Pipe Flowline System Transporting Waxy Hydrocarbons

2021 ◽  
Author(s):  
Keshawa Shukla
Keyword(s):  
Analytical Model ◽  
Production System ◽  
Thermal Model ◽  
Hydrate Formation ◽  
Pipe Production ◽  
Fluid Temperature ◽  
Waxy Crude Oil ◽  
Cooling Temperature ◽  
Fluid Properties ◽  
Transient Thermal

Abstract The proper understanding of cooling temperature and cooldown time for the operation of a subsea system producing hydrocarbons from the reservoir to the host facility is one of the important flow assurance issues for managing heat retention in the production system due to solids formation and their deposition. In this paper, an analytical transient thermal model is developed for determining the cooling temperature and cooldown time for shut-in operations of a subsea pipe-in-pipe production system, transporting waxy crude oil from the reservoir to the host facility. Here, the cooldown time is defined as the time when the fluid temperature approaches the wax appearance temperature before reaching the hydrate formation temperature during any shut-in operations. The analytical model builds upon an inhomogeneous transient method incorporating an internal temperature gradient. The model results are benchmarked against the commercial OLGA simulation results for a few selected deepwater pipe-in-pipe flowline configuration. The model predictions resemble well with OLGA results over a range of conditions. The analytical model could optimize dry insulation and cooldown time requirements efficiently for the assumed PIP flowline configurations and fluid properties under any subsea environments.

A new analytical model for reliability analysis of a launch vehicle system with limited test data

2018 ◽  
Vol 233 (9) ◽  
pp. 3482-3495
Author(s):  
V Murugesan ◽  
Sreejith Plappillimadam ◽  
VJ Saji ◽  
SS Maruthi ◽  
AK Anilkumar
Keyword(s):  
Reliability Analysis ◽  
Analytical Model ◽  
Test Data ◽  
Weighting Factor ◽  
Design Parameters ◽  
Launch Vehicles ◽  
Minimum Number ◽  
First Time ◽  
Propellant Rocket

Reliability is one of the critical design parameters for the launch vehicles and its systems. When the systems are ready to fly the first time, only limited test data are available and accordingly reliability assessed will be very low. However, in most cases, the new systems are derived and developed using the knowledge and experience gained from the heritage systems to meet the fresh challenges. Hence, the reliability assessed with the minimum number of tests done on the new system does not truly reflect the inherent reliability of the system. In this paper, an approach and a new analytical model are developed for the reliability assessment of systems with limited test data, giving an accurate weighting for the tests and flight experiences with similar systems. The method gives a systematic procedure for arriving at the weighting factor for test data of the pedigree system, with due consideration of the similarities between the systems and various factors influencing system reliability. The method is illustrated with a case study of a newly developed liquid propellant rocket system. The model is validated using the available test and flight data of two propulsion systems with adequate flight experience. The analytical model is generic in nature and can be applied to reliability analysis of any system, which has considerable similarities with a pedigree system.

Heat Transfer Performance During Condensation Inside Spiralled Micro-Fin Tubes

2004 ◽  
Vol 126 (3) ◽  
pp. 321-328 ◽  
Author(s):  
Jean-Pierre M. Bukasa ◽  
Leon Liebenberg ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Geometric Parameters ◽  
Experimental Results ◽  
Outer Diameter ◽  
Transfer Performance ◽  
Fin Tube ◽  
R 134A ◽  
Fin Tubes ◽  
Spiral Angle

The effect of the spiral angle on the heat transfer performance in micro-fin tube condensers has not yet been clearly established because other geometric parameters affecting the heat transfer performance were simultaneously varied in previous studies. This paper reports on the influence of the spiral angle on the heat transfer during condensation inside spiralled micro-fin tubes having all other geometric parameters constant. Tests were conducted for condensation of R-22, R-134a, and R-407C inside a smooth (9.52 mm outer diameter) and three micro-fin tubes with approximately the same diameter, having spiral angles of 10 deg, 18 deg, and 37 deg, respectively. Experimental results indicated a heat transfer augmentation with spiral angle increase. A new semi-empirical predictive correlation was developed for practical design of spiralled micro-fin tubes. The proposed new correlation predicted the majority of experimental results of the present study within a deviation zone of ±20%.

Application of an Analytical Model for Simulating Hydraulic Systems Containing Internal Lines With Turbulent Flow

2017 ◽  
Author(s):  
David A. Hullender ◽  
Natalie N. Snyder ◽  
Jan C. Gans
Keyword(s):  
Turbulent Flow ◽  
Frequency Response ◽  
Analytical Model ◽  
Simulation Models ◽  
Hydraulic Systems ◽  
Mean Flow ◽  
Pressure Transients ◽  
Fluid Properties ◽  
The Mean ◽  
Hydraulic Fracking

It is not uncommon for simulation models for the dynamics of hydraulic systems to contain fluid lines with turbulent flow. This paper demonstrates applications of an analytical model for pressure transients in lines with turbulent flow for lines with boundary conditions defined by hydraulic components such as pumps, valves, actuators, and restrictions; the model can be simplified for cases of laminar flow. The equations for conducting simulations with time varying inputs and for calculating eigenvalues of systems in which fluid lines are internal components are formulated. For an example demonstrating application of the equations, the model is used to simulate and optimize the performance of a hydraulic fracking system which involves the pumping of large volumes of water with additives through pipes under turbulent flow conditions into rock fissures. Specifically, the model is used to generate the frequency response of the flow transients in the pipe resulting from pump flow pulsations. This frequency response is then used to compute the eigenvalues of the system. The model is then used to conduct time domain simulations to determine the potential flow amplifications into rock fissures associated with pulsing the flow from the pump at the resonant frequency of the pressure transients in the pipe. The results reveal flow amplifications into the fissures of up to 22 times depending on the pulse shape of the input flow, the Reynolds number of the mean flow, the fluid properties of the slurry, and the length and diameter of the pipe.

Application of the 3ω Hot Wire Technique for Measurement of Fluid Thermophysical Properties

2007 ◽  
Author(s):  
Brandon W. Olson ◽  
Ali Fahham
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Analytical Model ◽  
Thermophysical Properties ◽  
Fluid Motion ◽  
Hot Wire ◽  
Resistance Thermometer ◽  
Bulk Fluid ◽  
Radiation Losses ◽  
Fluid Properties

The popular 3ω method of measuring thermophysical properties of solids is adapted for the simultaneous measurement of thermal conductivity and heat capacity in both liquids and gases. This technique is experimentally simple and has a lower susceptibility to random experimental noise, bulk fluid motion, radiation losses, and non-linear effects than other transient hot wire measurement methods. The compactness of the 3ω hotwire allows it to be used with different fluids in a variety of circumstances with very little specialized experimental equipment. Both the experimental setup and theoretical model are detailed. Experimental 3ω measurements were made in a variety of common fluids (air, water, and mineral oil) using commercially drawn 10μm platinum and 5μm tungsten hot wires which serve as both heating element and resistance thermometer. Measurements taken over a range of frequencies are numerically reduced to provide both thermal conductivity and heat capacity information. Experimental measurements and the corresponding analytical model are presented in terms of impedance or thermal resistance; a more physically meaningful and intuitive basis of comparison. Fluid properties are determined by curve-fitting an analytical model to experimental data using a least-squares approach. This technique allows both thermal conductivity and heat capacity (or thermal diffusivity) to be uniquely determined from a single measurement sequence.

Improvement of a Large Analytical Model Using Test Data

AIAA Journal ◽  
1983 ◽  
Vol 21 (8) ◽  
pp. 1168-1173 ◽  
Author(s):  
A. Berman ◽  
E. J. Nagy
Keyword(s):  
Analytical Model ◽  
Test Data

Design for Leakage in Flange Joints Under External Loads

2005 ◽  
Author(s):  
William J. Koves
Keyword(s):  
Internal Pressure ◽  
Analytical Model ◽  
Test Data ◽  
Pressure Vessel ◽  
Research Council ◽  
Bending Moments ◽  
Design Recommendations ◽  
Model Based ◽  
External Loads

This paper uses an analytical model based on the Pressure Vessel Research Council (PVRC) ROTT test gasket constants to compute leakage in gasketed flange joints subjected to internal pressure and external bending moments. The model results are compared with test data and design recommendations are made, consistent with the ASME/PVRC tightness based methodology.

Enhanced Condensation of Ethylene Glycol on Single Pin-Fin Tubes: Effect of Pin Geometry

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Hafiz Muhammad Ali ◽  
Adrian Briggs
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Ethylene Glycol ◽  
Heat Transfer Enhancement ◽  
Surface Area ◽  
Two Dimensional ◽  
Transfer Enhancement ◽  
Pin Fin ◽  
Fin Tube ◽  
Fin Tubes

This paper presents a fundamental study into the underlying mechanisms influencing heat transfer during condensation on enhanced surfaces. New experimental data are reported for condensation of ethylene glycol at near atmospheric pressure and low velocity on 11 different 3-dimensional pin-fin tubes tested individually. Enhancements of the vapor-side, heat-transfer coefficients were found between 3 and 5.5 when compared to a plain tube at the same vapor-side temperature difference. Heat-transfer enhancement was found to be strongly dependent on the active surface area of the tubes, i.e., on the surface area of the parts of the tube and pin surface not covered by condensate retained by surface tension. For all the tubes, vapor-side, heat-transfer enhancements were found to be approximately twice the corresponding active-area enhancements. The best performing pin-fin tube gave a heat-transfer enhancement of 5.5; 17% higher than obtained from “optimised” two-dimensional fin-tubes reported in the literature and about 24% higher than the “equivalent” two-dimensional integral-fin tube (i.e., with the same fin-root diameter, longitudinal fin spacing and thickness, and fin height). The effects of surface area and surface tension induced enhancement and retention are discussed in the light of the new data and those of previous investigations.

Effects of Crack Depth, Specimen Size, and Out-of-Plane Stress on the Fracture Toughness of Reactor Vessel Steels

1996 ◽  
Vol 118 (4) ◽  
pp. 415-423 ◽  
Author(s):  
Y.-J. Chao ◽  
P.-S. Lam
Keyword(s):  
Fracture Toughness ◽  
Analytical Model ◽  
Test Data ◽  
National Laboratory ◽  
Crack Depth ◽  
Specimen Size ◽  
Stress Criterion ◽  
Oak Ridge ◽  
Out Of Plane ◽  
Loading Parameter

Cleavage fracture toughness values for A533-B reactor pressure vessel (RPV) steel at -40°C obtained from test programs at Oak Ridge National Laboratory (ORNL) and University of Kansas (KU) are interpreted using the J-A2 analytical model. The KU test data are from smaller SENB specimens with a/w = 0.1 and 0.5. The ORNL test data are from 1) larger SENB specimens with a/w = 0.1 and 0.5, and 2) a six-point-bend cruciform specimen under either uniaxial or bi-axial loads. The analytical model is based on the critical stress criterion and takes into consideration the constraint effect using the second parameter A2 in addition to the generally accepted loading parameter J. It is demonstrated that the effects of crack depth (shallow versus deep), specimen size (small versus large), and loading type (uniaxial versus biaxial) on the fracture toughness from the test programs can be interpreted and predicted.

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