Steam Jet Condensation in a Pool: From Fundamental Understanding to Engineering Scale Analysis

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Chul-Hwa Song ◽  
Seok Cho ◽  
Hyung-Seok Kang
Keyword(s):  
Thermal Stratification ◽  
Hot Spot ◽  
Global Analysis ◽  
Turbulent Jet ◽  
Local Behavior ◽  
Dynamic Features ◽  
Water Pool ◽  
Thermal Mixing ◽  
Fundamental Understanding ◽  
Contact Condensation

The phenomena of direct contact condensation (DCC) of a steam jet submerged in a water pool occur because of the actuation of steam discharging devices in many industrial processes. There are practically two kinds of technical concerns to consider. The first is the thermal mixing in the water pool, and the other is the thermo-hydraulically induced mechanical loads acting on the structures of relevant systems. The two concerns are inter-related and can be well described only if the local behavior of the condensing steam jets and the resultant turbulent jet in a pool are well understood. In this paper, the DCC-related thermofluid dynamic features are discussed focusing on these two concerns. The fundamental characteristics of condensing steam jets are discussed, including the local behavior of condensing jets and the resultant turbulent jet, both of which importantly affect the macroscopic circulation in a pool. Then, a global analysis of thermal mixing in a pool from the viewpoints of the local hot spot and the thermal stratification are discussed with practical application to engineering design in mind.

Steam Jet Condensation in a Pool: From Fundamental Understanding to Engineering Scale Analysis

2010 ◽  
Author(s):  
Chul-Hwa Song
Keyword(s):  
Hot Spot ◽  
Fluid Dynamic ◽  
Global Analysis ◽  
Turbulent Jet ◽  
Local Analysis ◽  
Dynamic Features ◽  
Water Pool ◽  
Local Behaviour ◽  
Thermally Induced ◽  
Thermal Mixing

The phenomena of direct contact condensation (DCC) of steam jet submerged into a water pool occurs due to the actuation of steam discharging devices in many industrial processes and there are practically two kinds of technical concerns to consider. The one is a concern on the thermal mixing in water pool. The other concern is on thermo-hydraulically induced mechanical loads on the structures of relevant systems. Both concerns may be inter-related with each other in terms of thermally-induced hydrodynamic loads on the relevant system. There are two kinds of viewpoints in terms of DCC-induced thermal mixing in a pool: the local hot spot, which may affect the stability of condensation phenomena, and the thermal stratification, which usually exists over the whole pool region. Both aspects can be well described only if the local behaviour of condensing steam jet and the resultant turbulent jet in a pool are well understood. In this paper, the DCC-related thermo-fluid dynamic features are discussed, based mainly on our experiences of developing the relevant engineering systems over the past years. Fundamental characteristics of condensing steam jets are discussed, including the local behaviour of condensing jets and the resultant turbulent jet to importantly affect the macroscopic circulation in a pool. Then the local analysis of condensing jet behaviour and the global analysis of thermal mixing in a pool are discussed with practical application to engineering in mind.

scholarly journals Approach and Development of Effective Models for Simulation of Thermal Stratification and Mixing Induced by Steam Injection into a Large Pool of Water

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Hua Li ◽  
Walter Villanueva ◽  
Pavel Kudinov
Keyword(s):  
Thermal Stratification ◽  
Large Scale ◽  
Steam Injection ◽  
Small Time ◽  
Small Scale ◽  
Computationally Efficient ◽  
Thermal Mixing ◽  
Large Pool ◽  
Effective Models ◽  
Contact Condensation

Steam venting and condensation in a large pool of water can lead to either thermal stratification or thermal mixing. In a pressure suppression pool (PSP) of a boiling water reactor (BWR), consistent thermal mixing maximizes the capacity of the pool while the development of thermal stratification can reduce the steam condensation capacity of the pool which in turn can lead to pressure increase in the containment and thereafter the consequences can be severe. Advanced modeling and simulation of direct contact condensation in large systems remain a challenge as evident in commercial and research codes mainly due to small time-steps necessary to resolve contact condensation in long transients. In this work, effective models, namely, the effective heat source (EHS) and effective momentum source (EMS) models, are proposed to model and simulate thermal stratification and mixing during a steam injection into a large pool of water. Specifically, the EHS/EMS models are developed for steam injection through a single vertical pipe submerged in a pool under two condensation regimes: complete condensation inside the pipe and chugging. These models are computationally efficient since small scale behaviors are not resolved but their integral effect on the large scale flow structure in the pool is taken into account.

Numerical Simulation of Thermal Stratification in the Upper Plenum of Fast Reactor

2013 ◽  
Author(s):  
Seok-Ki Choi ◽  
Tae-Ho Lee
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Thermal Stratification ◽  
Numerical Solutions ◽  
Steady State Solution ◽  
Temporal Variations ◽  
State Solution ◽  
Thermal Mixing ◽  
Commercial Code ◽  
Inlet Conditions

A numerical analysis of the thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained, and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for the steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (∼300 seconds). However, the transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A near homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates.

CFD simulation of steam jet-induced thermal mixing in subcooled water pool

2009 ◽  
Vol 239 (12) ◽  
pp. 2849-2863 ◽  
Author(s):  
Young-Tae Moon ◽  
Hee-Do Lee ◽  
Goon-Cherl Park
Keyword(s):  
Cfd Simulation ◽  
Water Pool ◽  
Thermal Mixing ◽  
Subcooled Water

Full Stochastic Fatigue Analysis for Kizomba ‘A’ FPSO-Hull Interface Design

2003 ◽  
Author(s):  
Jeong Heon Na ◽  
In Hye Lee ◽  
Woo Seung Sim ◽  
Hyun Soo Shin
Keyword(s):  
Interface Design ◽  
Hot Spot ◽  
Global Analysis ◽  
Model Analysis ◽  
Fatigue Analysis ◽  
Point Of View ◽  
Sea State ◽  
Hot Spot Stress ◽  
Tower Foundation ◽  
Long Operation

As the offshore oilfields shift into the deeper ocean of less infra, FPSOs become a popular solution. Many FPSOs operate in fields where they are expected to stay for decades without drydocking for maintenance. Currently one of the most active area of the FPSO installation is the west Africa offshore where the sea state is benign and the swell from the south is dominant and the water depth is deep. In the case of long operation in the benign site, the fatigue is rather important in the structural design point of view. This paper describes the first extensive practical application of the full stochastic fatigue analysis method to the design of the FPSO-hull interface design like topside supports, flare tower foundation, riser porches, caissons, crane pedestals, mooring foundations, helideck connections, deck penetrations and etc. Especially, topside support is highlighted in detail because of its potential inertia loading due to heavy weight and importance in fabrication stage. The full length of Kizomba ‘A’ FPSO being built in Hyundai Heavy Industries is modeled for the global analysis and the boundary conditions from the global model analysis are transferred for the local model analysis. Some discussions of screening analysis and hot spot stress calculation and roll damping evaluation are also presented.

Suppression of thermal stratification in gravity driven water pool of an advanced reactor using shrouds

2013 ◽  
Vol 58 ◽  
pp. 221-227 ◽  
Author(s):  
P.K. Verma ◽  
A.K. Nayak ◽  
Vikas Jain ◽  
P.K. Vijayan ◽  
K.K. Vaze
Keyword(s):  
Thermal Stratification ◽  
Water Pool ◽  
Gravity Driven

scholarly journals Global analysis of LARP1 translation targets reveals tunable and dynamic features of 5′ TOP motifs

2020 ◽  
Vol 117 (10) ◽  
pp. 5319-5328 ◽  
Author(s):  
Lucas Philippe ◽  
Antonia M. G. van den Elzen ◽  
Maegan J. Watson ◽  
Carson C. Thoreen
Keyword(s):  
Transcription Initiation ◽  
Rna Binding ◽  
Global Analysis ◽  
Mrna Translation ◽  
Nutrient Sensing ◽  
Regulatory Sequences ◽  
Dynamic Features ◽  
Discrete Elements ◽  
Full Spectrum ◽  
Terminal Oligopyrimidine

Terminal oligopyrimidine (TOP) motifs are sequences at the 5′ ends of mRNAs that link their translation to the mTOR Complex 1 (mTORC1) nutrient-sensing signaling pathway. They are commonly regarded as discrete elements that reside on ∼100 mRNAs that mostly encode translation factors. However, the full spectrum of TOP sequences and their prevalence throughout the transcriptome remain unclear, primarily because of uncertainty over the mechanism that detects them. Here, we globally analyzed translation targets of La-related protein 1 (LARP1), an RNA-binding protein and mTORC1 effector that has been shown to repress TOP mRNA translation in a few specific cases. We establish that LARP1 is the primary translation regulator of mRNAs with classical TOP motifs genome-wide, and also that these motifs are extreme instances of a broader continuum of regulatory sequences. We identify the features of TOP sequences that determine their potency and quantify these as a metric that accurately predicts mTORC1/LARP1 regulation called a TOPscore. Analysis of TOPscores across the transcriptomes of 16 mammalian tissues defines a constitutive “core” set of TOP mRNAs, but also identifies tissue-specific TOP mRNAs produced via alternative transcription initiation sites. These results establish the central role of LARP1 in TOP mRNA regulation on a transcriptome scale and show how it connects mTORC1 to a tunable and dynamic program of gene expression that is tailored to specific biological contexts.

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