Natural Convection Flow of a Two-Phase Dusty Gas with Variable Thermophysical Properties

2017 ◽  
Vol 31 (3) ◽  
pp. 651-659 ◽  
Author(s):  
Naheed Begum ◽  
Sadia Siddiqa ◽  
Md. Anwar Hossain ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Natural Convection ◽  
Thermophysical Properties ◽  
Convection Flow ◽  
Dusty Gas ◽  
Natural Convection Flow ◽  
Two Phase

Numerical Solutions of Natural Convection Flow of a Dusty Nanofluid About a Vertical Wavy Truncated Cone

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Sadia Siddiqa ◽  
Naheed Begum ◽  
M. A. Hossain ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Natural Convection ◽  
Mass Transport ◽  
Numerical Solutions ◽  
Convection Flow ◽  
Governing Equations ◽  
Natural Convection Flow ◽  
Two Phase ◽  
Heat And Mass Transport ◽  
Implicit Finite Difference ◽  
Control Skin

This paper reports the numerical results for the natural convection flow of a two-phase dusty nanofluid along a vertical wavy frustum of a cone. The general governing equations are transformed into parabolic partial differential equations, which are then solved numerically with the help of implicit finite difference method. Comprehensive flow formations of carrier and dusty phases are given with the aim to predict the behavior of heat and mass transport across the heated wavy frustum of a cone. The effectiveness of utilizing the nanofluids to control skin friction and heat and mass transport is analyzed. The results clearly show that the shape of the waviness changes when nanofluid is considered. It is shown that the modified diffusivity ratio parameter, NA, extensively promotes rate of mass transfer near the vicinity of the cone, whereas heat transfer rate reduces.

Influence of Variable Thermophysical Properties on Natural Convection Flow

2017 ◽  
Vol 31 (2) ◽  
pp. 358-365 ◽  
Author(s):  
Abdullah A. A. A. Al-Rashed ◽  
Sadia Siddiqa ◽  
Naheed Begum ◽  
Md. Anwar Hossain
Keyword(s):  
Natural Convection ◽  
Thermophysical Properties ◽  
Convection Flow ◽  
Natural Convection Flow

Erratum: Influence of Variable Thermophysical Properties on Natural Convection Flow

2020 ◽  
Vol 34 (4) ◽  
pp. 870-870
Author(s):  
Abdullah A. A. A. Al-Rashed ◽  
Sadia Siddiqa ◽  
Naheed Begum ◽  
Md. Anwar Hossain
Keyword(s):  
Natural Convection ◽  
Thermophysical Properties ◽  
Convection Flow ◽  
Natural Convection Flow

Experimental Study of the Cooling Performance of the PAFS (Passive Auxiliary Feedwater System) During Transient Operation

2013 ◽  
Author(s):  
Byoung-Uhn Bae ◽  
Seok Kim ◽  
Yu-Sun Park ◽  
Kyoung-Ho Kang
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Two Phase ◽  
Cooling Performance ◽  
Start Up ◽  
Gas Effect ◽  
Effect Test

PAFS (Passive Auxiliary Feedwater System) is one of the advanced passive safety systems adopted in the APR+ (Advanced Power Reactor plus) being developed in Korea. The PAFS aims at completely replacing the conventional active auxiliary feedwater system by cooling down the steam generator’s secondary side with a natural driving force mechanism; i.e., it can remove the core decay heat by condensing steam in a passive condensation heat exchanger (PCHX) submerged inside the passive condensation cooling tank (PCCT). With an aim of validating the cooling and operational performance of the PAFS, the separate effect test facility named as PASCAL (PAFS Condensing Heat Removal Assessment Loop) has been constructed. In this study, postulated transient scenarios occurring in the PAFS were simulated to evaluate the performance of the condensation heat transfer and investigate the thermal hydraulic phenomena of the two-phase natural convection flow. The transient test matrix is composed of inadvertent MSSV (Main Steam Safety Valve) opening test (MO), PAFS start-up actuation test (SU), and non-condensable gas effect test (NC). In the MSSV opening test, MSSV was intentionally opened and closed several times and the characteristics of the natural convection flow were investigated. The experimental results showed that the cooling performance of the PAFS could be recovered after inadvertent opening and closing the MSSV. Start-up actuation test simulated the initial transient when the PAFS actuation signal was generated and the natural convection flow was initiated in the loop, and any significant two-phase flow instability was not observed in the test. The purpose of the non-condensable gas effect test is to study the characteristics of the condensation heat transfer in the heat exchanger when the nitrogen gas was injected. The test results proved that the existence of the non-condensable gas up to 1% of the steam did not produce a meaningful decrease of the cooling capability in the PAFS. From the experimental results described above, the cooling and operating performance of the PAFS was validated with respect to occurrence of the various transient scenarios and it was proved that the function of the PAFS can be effectively performed during the transient situation. The result will be also utilized in validation of the thermal hydraulic system code in the future.

Two-phase natural convection flow of a dusty fluid

2015 ◽  
Vol 25 (7) ◽  
pp. 1542-1556 ◽  
Author(s):  
Sadia Siddiqa ◽  
M. Anwar Hossain ◽  
Suvash C Saha
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Prandtl Number ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Two Phase ◽  
Metal Mixture ◽  
Content Type ◽  
Dusty Fluid ◽  
Wide Range

Purpose – The purpose of this paper is to conduct a detailed investigation of the two-dimensional natural convection flow of a dusty fluid. Therefore, the incompressible boundary layer flow of a two-phase particulate suspension is investigated numerically over a semi-infinite vertical flat plate. Comprehensive flow formations of the gas and particle phases are given in the boundary layer region. Primitive variable formulation is employed to convert the nondimensional governing equations into the non-conserved form. Three important two-phase mechanisms are discussed, namely, water-metal mixture, oil-metal mixture and air-metal mixture. Design/methodology/approach – The full coupled nonlinear system of equations is solved using implicit two point finite difference method along the whole length of the plate. Findings – The authors have presented numerical solution of the dusty boundary layer problem. Solutions obtained are depicted through the characteristic quantities, such as, wall shear stress coefficient, wall heat transfer coefficient, velocity distribution and temperature distribution for both phases. Results are interpreted for wide range of Prandtl number Pr (0.005-1,000.0). It is observed that thin boundary layer structures can be formed when mass concentration parameter or Prandtl number (e.g. oil-metal particle mixture) are high. Originality/value – The results of the study may be of some interest to the researchers of the field of chemical engineers.

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