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1 – 10 of over 2000
Article
Publication date: 1 June 2004

Y.J. Ren and J.E. Ruckman

This paper investigates the behaviour of condensation in three‐layer waterproof breathable fabrics for clothing. An attempt has been made to consider water vapour transfer…

Abstract

This paper investigates the behaviour of condensation in three‐layer waterproof breathable fabrics for clothing. An attempt has been made to consider water vapour transfer when condensation occurs within the three‐layer waterproof breathable fabrics based on the simultaneous heat and mass transfer theory developed by Motakef and El‐Maher and diffusion and condensation theory developed by Wijeysundera et al. According to the analysis made of existing theory, it is possible to model condensation within fabrics and laminates using the thermodynamic equations outlined in this paper, which can assist in predicting the performance of textiles and help to understand the comfort of performance clothing. It is noted that the condensation problem may be solved by changing some physical properties of a three‐layer waterproof breathable fabric. The water vapour transfer out of the fabric can be improved, and consequently the formation of condensation reduced, by decreasing the thickness of the waterproof membrane and outer layer fabric or by increasing the average diffusion coefficient of the outer layer and membrane. A decrease in the thickness of the lining could increase the water vapour transfer from the hot side to the interface between the dry‐wet regions, but this would also increase the condensation. Increasing the diffusion coefficient of the lining will also increase both water vapour transfer from the hot side and condensation.

Details

International Journal of Clothing Science and Technology, vol. 16 no. 3
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 11 October 2018

Xu Han, Zhonghe Han, Wei Zeng, Peng Li and Jiangbo Qian

The purpose of this paper is to study the condensation flow of wet steam in the last stage of a steam turbine and to obtain the distribution of condensation parameters…

Abstract

Purpose

The purpose of this paper is to study the condensation flow of wet steam in the last stage of a steam turbine and to obtain the distribution of condensation parameters such as nucleation rate, Mach number and wetness.

Design/methodology/approach

Because of the sensitivity of the condensation parameter distribution, a double fluid numerical model and a realizable k-ε-kd turbulence model were applied in this study, and the numerical solution for the non-equilibrium condensation flow is provided.

Findings

The simulation results are consistent with the experimental results of the Bakhtar test. The calculation results indicate that the degree of departure from saturation has a significant impact on the wet steam transonic condensation flow. When the inlet steam deviates from the saturation state, shock wave interference and vortex mixing also have a great influence on the distribution of water droplets.

Originality/value

The research results can provide reference for steam turbine wetness losses evaluation and flow passage structure optimization design.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 10
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 July 2014

Dongliang Sun, Jinliang Xu and Peng Ding

Based on the numerical research on the relationship between the flow pattern transition and the condensation heat transfer in circular microchannels, the purpose of this…

Abstract

Purpose

Based on the numerical research on the relationship between the flow pattern transition and the condensation heat transfer in circular microchannels, the purpose of this paper is to bring forward a concept of external separation circular microchannel to regulate and control the flow pattern for enhancing the condensation heat transfer.

Design/methodology/approach

The numerical research is based on the volume of fluid method and the vapor-liquid phase change model proposed by the present authors.

Findings

By numerical research on the condensation process of water in a general circular microchannel, it is discovered that, with the increase of the inlet velocity and the reduction of the temperature difference between the saturation temperature and the channel wall temperature, the bubble detachment frequency is raised and the water vapor condensation length is extended, representing an exponential growth. Therefore, for the condensation process with low temperature difference and high mass flow rate, it is in urgent need to regulate and control the flow pattern.

Originality/value

To prevent the flow pattern in the general circular microchannel converted from annular flow to slug flow and then to bubble flow, this paper brings forward a concept of external separation circular microchannel, which regulates and controls the flow pattern by discharging partial liquid from the annular wall opening. After regulation and control, the flow pattern is converted from original periodic annular flow/slug flow/bubble flow to current stable annular flow. Accordingly, the heat transfer performance is enhanced and the condensation length is lowered remarkably.

Details

Engineering Computations, vol. 31 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 29 March 2011

Jie Sun, Ya‐Ling He and Wen‐Quan Tao

The purpose of this paper is to focus on the condensation process of hot vapor on smooth/rough walls and find how the condensation film forms and grows. The influences of…

Abstract

Purpose

The purpose of this paper is to focus on the condensation process of hot vapor on smooth/rough walls and find how the condensation film forms and grows. The influences of the roughness and the wettability on condensation are especially analyzed.

Design/methodology/approach

The non‐equilibrium molecular dynamics simulation method is used to simulate the condensation. In order to maintain the process, a simple and effective molecule insertion mechanics is proposed.

Findings

The results show that the wall‐neighboring liquid structure becomes more regular with stronger wettability. The temporal parametric profiles show that the condensation does not progress at a constant rate but exhibit obvious unsteady characteristics of gradual deceleration, especially for strong wettability cases. Analysis based on heat and mass transfer indicates that the influence of wettability is quite superior to that of the roughness. The enhancement should be explained by the more fluent and effective energy exchange between solid and liquid particles caused by strong solid‐liquid coupling other than by the ordering structure itself.

Practical implications

The paper's findings suggest that the wettability should be paid special attention when the heat transfer performance of the microscale condensation is predominantly focused on.

Originality/value

The paper provides a vapor‐liquid‐solid model with molecule insertion. This model can be used to evaluate the contact thermal resistance and the thermal boundary conditions in condensation under different geometric conditions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 21 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Open Access
Article
Publication date: 11 March 2022

Andrei Khrennikov

This paper aims to present the basic assumptions for creation of social Fröhlich condensate and attract attention of other researchers (both from physics and…

Abstract

Purpose

This paper aims to present the basic assumptions for creation of social Fröhlich condensate and attract attention of other researchers (both from physics and socio-political science) to the problem of modeling of stability and order preservation in highly energetic society coupled with social energy bath of high temperature.

Design/methodology/approach

The model of social Fröhlich condensation and its analysis are based on the mathematical formalism of quantum thermodynamics and field theory (applied outside of physics).

Findings

The presented quantum-like model provides the consistent operational model of such complex socio-political phenomenon as Fröhlich condensation.

Research limitations/implications

The model of social Fröhlich condensation is heavily based on theory of open quantum systems. Its consistent elaboration needs additional efforts.

Practical implications

Evidence of such phenomenon as social Fröhlich condensation is demonstrated by stability of modern informationally open societies.

Social implications

Approaching the state of Fröhlich condensation is the powerful source of social stability. Understanding its informational structure and origin may help to stabilize the modern society.

Originality/value

Application of the quantum-like model of Fröhlich condensation in social and political sciences is really the novel and original approach to mathematical modeling of social stability in society exposed to powerful information radiation from mass-media and Internet-based sources.

Article
Publication date: 5 May 2020

Erdem Çiftçi and Adnan Sözen

The purpose of this study is to experimentally and numerically scrutinize the heat transfer enhancement in pool boiling and condensation by changing the hydrophilicity or…

510

Abstract

Purpose

The purpose of this study is to experimentally and numerically scrutinize the heat transfer enhancement in pool boiling and condensation by changing the hydrophilicity or hydrophobicity properties of the working fluid, i.e. by use of nanofluid solution.

Design/methodology/approach

For specifying the effects of nanoparticle concentration on heat transfer properties, two different nanofluid solutions (h-BN/DCM and SiO2/DCM) at three different volumetric concentrations were prepared and tested under different heat flux conditions. Boiling curves, alterations in pressure with heat flux and heat transfer coefficients for both boiling and condensation processes were obtained and viscosity measurements were performed for dichloromethane (DCM) and each working fluid was prepared. In addition, a series of numerical simulations, via computational fluid dynamics approach, was performed for specifying the evaporation–condensation phenomena and temperature and velocity distributions.

Findings

Nanoparticle addition inside the base fluid increased the thermal characteristics of the base fluid significantly. For the experimental results of h-BN/DCM nanofluid, the increment rate in heat transfer coefficient for saturation boiling, after-saturation boiling and condensation processes was found as 27.59%, 14.44% and 15%, respectively.

Originality/value

The novelty of this comparison study is that there is no such experimental and numerical comparison study in literature for DCM fluid, which concentrates on thermal performance enhancement and compares the effect of different kinds of nanoparticles on heat transfer characteristics for boiling–condensation processes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 4 October 2013

Mohammadjavad Mahdavinejad, Kavan Javanroodi and Leyli Hashemi Rafsanjani

The purpose of this paper is to investigate moisture problems and defects which have been caused by condensation in historic buildings. Emphasis has been put on finding…

Abstract

Purpose

The purpose of this paper is to investigate moisture problems and defects which have been caused by condensation in historic buildings. Emphasis has been put on finding condensation possibility on the external walls and inside temperature and humidity.

Design/methodology/approach

A third-part study including survey method to identify moisture problems and exhaustion, then determining indoor and outdoor temperature and relative humidity in a two-part survey within four days periods, and finally computer modeling and simulation to finding condensation possibility in the building walls by WUFI and THERM software.

Findings

Results indicated that the case study has serious defects and almost 7.5°C differences (Δt) and about 6 percent relative humidity differences (Δh) between indoor and outdoor temperature, and from analyzing computer simulations, condensation risk occurrence between wall layers is witnessed. Also this study shows that some climatic methods applied by traditional architects despite enhancing thermal comfort have caused damages and defects to the building envelope and structure. In this paper, the authors suggest a method to reduce condensation possibility by active ventilation for reducing temperature differences.

Originality/value

While there is a lock of technical researches and investigations about architectural heritages conservation, this study tries to perform a technical research and filling the gaps in this subject area.

Details

World Journal of Science, Technology and Sustainable Development, vol. 10 no. 4
Type: Research Article
ISSN: 2042-5945

Keywords

Article
Publication date: 30 September 2019

Rebecca Warren, David Bernard Carter and Christopher J. Napier

The purpose of this paper is to investigate an element of the internal politics of standard setting by reference to the International Accounting Standards Board’s (IASB…

Abstract

Purpose

The purpose of this paper is to investigate an element of the internal politics of standard setting by reference to the International Accounting Standards Board’s (IASB) movement to the International Financial Reporting Standard for Small and Medium-Sized Entities (IFRS for SMEs). The authors examine the politics of the IASB’s expertise in technocratic governance by focussing on how the IASB defined SMEs, gave the standard a title and issued a guide for micro-entities.

Design/methodology/approach

The narrative case study focusses on central “moments” in the development of IFRS for SMEs. The authors employ Laclau and Mouffe’s condensation, displacement and overdetermination to illustrate embedded politics in articulating IFRS for SMEs.

Findings

The authors extend literature on the internal politics of standard setting, such as agenda setting, by examining the condensing of disagreements between experts and political pressures and processes into central decision moments in IFRS for SMEs. The authors illustrate these moments as overdetermined, manifesting in an act of displacement through the production of a micro-entity guide. This form of politics is hidden due to the IASB’s attempt to protect their technocratic neutrality through fixing meaning.

Originality/value

The authors make three contributions: first, overdetermination through condensation and displacement illustrates the embedded nature of politics in regulatory settings, such as the IASB. Second, the authors provide a theoretical explanation of the IASB’s movement from listed entities to IFRS for SMEs, drawing on Laclau and Mouffe. Third, the authors reinforce the necessity of interrogating the internal politics of standard setting to challenge claims of technocracy.

Details

Accounting, Auditing & Accountability Journal, vol. 33 no. 1
Type: Research Article
ISSN: 0951-3574

Keywords

Article
Publication date: 8 January 2020

Xu Han, Xiangyu Liu, Yunyun Yuan and Zhonghe Han

The flow state of wet steam will affect the thermodynamic and aerodynamic characteristics of steam turbine. The purpose of this study is to effectively control the wetness…

Abstract

Purpose

The flow state of wet steam will affect the thermodynamic and aerodynamic characteristics of steam turbine. The purpose of this study is to effectively control the wetness losses caused by wet steam condensation, and hence a cascade of 600 MW steam turbine was taken as the research object.

Design/methodology/approach

The influence of blade surface roughness on the condensation characteristics was analyzed, and the dehumidification mechanism and wetness control effect were obtained.

Findings

With the increase of blade surface roughness, the peak nucleation rate decreases gradually. According to the Mach number distribution on the blade surface, there is a sensitive region for the influence of roughness on the aerodynamic performance of cascade. The sensitive region of nucleation rate roughness should be between 50 and 150 µm.

Originality/value

The increase of blade surface roughness will increase the dynamic loss in cascade, but it can reduce the thermodynamic loss caused by condensation to a certain extent.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 3 January 2017

Shuyuan Liu and Tat L. Chan

The purpose of this paper is to study the complex aerosol dynamic processes by using this newly developed stochastically weighted operator splitting Monte Carlo (SWOSMC) method.

Abstract

Purpose

The purpose of this paper is to study the complex aerosol dynamic processes by using this newly developed stochastically weighted operator splitting Monte Carlo (SWOSMC) method.

Design/methodology/approach

Stochastically weighted particle method and operator splitting method are coupled to formulate the SWOSMC method for the numerical simulation of particle-fluid systems undergoing the complex simultaneous processes.

Findings

This SWOSMC method is first validated by comparing its numerical simulation results of constant rate coagulation and linear rate condensation with the corresponding analytical solutions. Coagulation and nucleation cases are further studied whose results are compared with the sectional method in excellent agreement. This SWOSMC method has also demonstrated its high numerical simulation capability when used to deal with simultaneous aerosol dynamic processes including coagulation, nucleation and condensation.

Originality/value

There always exists conflict and tradeoffs between computational cost and accuracy for Monte Carlo-based methods for the numerical simulation of aerosol dynamics. The operator splitting method has been widely used in solving complex partial differential equations, while the stochastic-weighted particle method has been commonly used in numerical simulation of aerosol dynamics. However, the integration of these two methods has not been well investigated.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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