Computational Fluid Dynamics Studies on Unstable Oscillatory Direct Contact Condensation of Subsonic Steam Jets in Water Cross-Flow

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Jayachandran K. Narayanan ◽  
Arnab Roy ◽  
Parthasarathi Ghosh
Keyword(s):  
Direct Contact ◽  
Liquid Velocity ◽  
Rocket Engine ◽  
Cross Flow ◽  
Liquid Pool ◽  
Liquid Oxygen ◽  
Design Parameters ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Contact Condensation

Abstract In the last decade, researchers working on direct contact condensation (DCC) have focused their attention on studying the effect of liquid cross-flow, in contrast to the conventional stagnant liquid pool condensers. Currently, the major applications of DCC in liquid cross-flow include the sterilization process of milk and the mixing of oxygen-rich turbine drive gas with liquid oxygen (LOX) at the booster turbopump exit of a typical staged combustion cycle-based rocket engine. In this work, attempt has been made to develop and validate a two-fluid two-phase model for predicting the complex phenomena of steam injection into a cross-flow of subcooled water. A correlation for interaction length scale has been developed for DCC cases. The correlation includes the effect of all the critical operating parameters such as liquid subcooling, steam mass flux, and liquid velocity, which hitherto has not been available in the literature. The unstable nature of steam plumes has been investigated, and critical Weber numbers for predicting stable to unstable transition in a DCC cycle have been computed. The associated pressure and temperature oscillations due to unstable nature of plume have been studied. The critical design parameters for direct contact condenser such as the heat transfer coefficients and dimensionless vapor penetration lengths have been quantified and analyzed.

CFD Analysis of Direct Contact Condensation (DCC) of Subsonic Steam Jets in a Cross-Flow of Water Using a Two-Fluid Model

2018 ◽  
Author(s):  
Jayachandran K. Narayanan ◽  
Arnab Roy ◽  
Parthasarathi Ghosh
Keyword(s):  
Heat Transfer ◽  
Direct Contact ◽  
Fluid Model ◽  
Cross Flow ◽  
Liquid Oxygen ◽  
Transfer Coefficients ◽  
Flowing Liquid ◽  
High Heat Transfer ◽  
Contact Condensation ◽  
Two Fluid

Direct contact condensation occurs when a vapor comes in contact with the liquid of the same fluid and is accompanied by very high heat transfer coefficients compared to the conventional heat exchanging processes. Many researchers have investigated the direct contact condensation of steam jets in a pool of subcooled water. In the last decade, the potential of flowing liquid as an enhanced heat transfer medium in comparison with the stationary pool of liquid was explored by various researchers. Also, in some configurations of staged combustion cycle based rocket engine, the oxygen-rich gas is injected into flowing liquid oxygen to improve the heat transfer characteristics. Hence, there is a need to investigate the direct contact condensation of vapor jets in a cross flow of liquid. A two-fluid particle based multiphase formulation with thermal phase change model has been implemented in the present investigation to capture the direct contact condensation phenomena. The data obtained from numerical simulations are validated with the experimental results of Clerx et al., [1]. Further, studies on plume shapes, interfacial area and pressure amplitudes are reported.

A Physically Based, One-Dimensional Two-Fluid Model for Direct Contact Condensation of Steam Jets Submerged in Subcooled Water

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
David Heinze ◽  
Thomas Schulenberg ◽  
Lars Behnke
Keyword(s):  
Direct Contact ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Two Fluid Model ◽  
Contact Condensation ◽  
Two Fluid

A simulation model for the direct contact condensation of steam in subcooled water is presented that allows determination of major parameters of the process, such as the jet penetration length. Entrainment of water by the steam jet is modeled based on the Kelvin–Helmholtz and Rayleigh–Taylor instability theories. Primary atomization due to acceleration of interfacial waves and secondary atomization due to aerodynamic forces account for the initial size of entrained droplets. The resulting steam-water two-phase flow is simulated based on a one-dimensional two-fluid model. An interfacial area transport equation is used to track changes of the interfacial area density due to droplet entrainment and steam condensation. Interfacial heat and mass transfer rates during condensation are calculated using the two-resistance model. The resulting two-phase flow equations constitute a system of ordinary differential equations, which is solved by means of the explicit Runge–Kutta–Fehlberg algorithm. The simulation results are in good qualitative agreement with published experimental data over a wide range of pool temperatures and mass flow rates.

Hydrodynamics of the steam-water two-phase flows behind a pair of bluff cylinderical bodies inside and around the wake region

2020 ◽  
pp. 095440622097167
Author(s):  
Afrasyab Khan ◽  
Khairuddin Sanaullah ◽  
Shahzad Maqsood Khan ◽  
Andrew Ragai Henry Rigit ◽  
Atta Ullah
Keyword(s):  
Direct Contact ◽  
Industrial Processes ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Wake Region ◽  
Reynolds Stresses ◽  
Two Phase Flows ◽  
Two Phase ◽  
The Core ◽  
Contact Condensation

A significant number of natural and industrial phenomena exist, where steam-water, two-phase flows face resistance due to the cylindrical shaped bodies. It is useful to explore such flows for their direct relevance to the steam driven industrial processes having Direct Contact Condensation (DCC) as the core phenomena for heat, mass, and momentum transfer. An experimental setup has been fabricated to study the influence of twin, different sized cylinders with a gap between them on the formation of wake region as the steam-water flow past the cylinders. Hot and cold wire sensors were used to measure the fluctuations in the velocity and temperature respectively of the flow within the wake and the region surrounding wake. The diameter of the smaller cylinder was fixed as 0.5 cm and the dimensions of the larger cylinder was varied from 1, 1.5 and 2.0 cm. Values for the fluctuating velocity were measure for all the cases and based on these measurements, the turbulent normal stresses and Reynolds shear stresses were determined. The asymmetry of the wake region increases by raising the gap between the two cylinders as the wake region aligned to the smaller cylinder has been deflected larger than the wake aligned to the larger cylinder. The wake asymmetry signified the possible effect of buoyancy on the thermal and momentum diffusivities, which was emphasized here through the measured values of turbulent normal and Reynolds stresses.

An Experimental Investigation of OC-OTEC Direct-Contact Condensation and Evaporation Processes

1984 ◽  
Vol 106 (1) ◽  
pp. 120-127 ◽  
Author(s):  
R. G. Sam ◽  
B. R. Patel
Keyword(s):  
Heat Transfer ◽  
Direct Contact ◽  
Turbulent Jets ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Air Content ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy ◽  
Contact Condensation

Heat transfer data are presented for direct-contact evaporator and condenser geometries suitable for Open-Cycle Ocean Thermal Energy Conversion (OC-OTEC) applications. Falling turbulent jets and films were tested at typical operating conditions. The flash evaporator performance was relatively constant over the range of conditions tested, with efficiencies as high as 95 percent due to the breakup of the jets (or films) into sprays. The condenser performance was only affected by the jet or film Reynolds number and the steam air content. Condenser heat transfer coefficients of the order of 27 kW/m2 °C were achieved with jets which were higher than those obtained with films. An empirical correlation was developed for the condenser data after it was shown that none of the existing correlations found in the literature could correlate all of the data trends observed.

scholarly journals Temperature fields induced by direct contact condensation of steam in a cross-flow in a channel

2011 ◽  
Vol 47 (8) ◽  
pp. 981-990 ◽  
Author(s):  
N. Clerx ◽  
L. G. M. van Deurzen ◽  
A. Pecenko ◽  
R. Liew ◽  
C. W. M. van der Geld ◽  
...  
Keyword(s):  
Direct Contact ◽  
Cross Flow ◽  
Temperature Fields ◽  
Contact Condensation

Analytical Study of Flow Regimes for Direct Contact Condensation Based on Parametrical Investigation

2005 ◽  
Vol 127 (1) ◽  
pp. 20-25 ◽  
Author(s):  
Anka Petrovic
Keyword(s):  
Direct Contact ◽  
Analytical Study ◽  
Nuclear Reactor ◽  
Flow Regimes ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Jet Pumps ◽  
Different Shapes ◽  
Contact Condensation ◽  
Limited Accuracy

Various industrial devices exist where direct contact condensation (DCC) of steam in water takes place. Typical examples are the nuclear reactor coolant systems, steam driven jet pumps, and condensers. The modeling of steam condensation is crucial to obtain an appropriate design of such devices. Present models designed for DCC have shown limited agreement with experimental data. Computation of the flow regimes is performed with limited accuracy, due to initial model settings and empirical correlations, which form a main drawback in the computation of DCC related problems. This study, which is a part of a PhD study, presents an investigation of the steam-water interface for various conditions of steam and water, using the computation of balance equations and jump conditions. A simple mathematical model to predict the location of the condensation interface for four different shapes of steam plume at different heat transfer coefficients is presented which will be further developed into an advanced computational model for DCC.

Sign in / Sign up

Export Citation Format

Share Document