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Article
Publication date: 18 May 2010

Jung‐Chang Wang

The purpose of this paper is to describe how a traditional metal base plate is replaced with a vapour chamber, a two‐phase flow heat transfer module with high heat…

Abstract

Purpose

The purpose of this paper is to describe how a traditional metal base plate is replaced with a vapour chamber, a two‐phase flow heat transfer module with high heat transfer efficiency, to effectively reduce the temperature of heat sources as graphic processing unit (GPU) of smaller area and higher power.

Design/methodology/approach

As a first step, the nature of flow field of a vapour chamber‐based thermal module with heat sink is simulated and analysed through computational numerical method. Second, a sample is prepared according to the theoretical results and the performance of thermal modules is tested together with thermal performance experiment.

Findings

The results show that when the fin height from vapour chamber top to fan bottom area is more than 3 mm and not more than 8 mm, the vapour chamber‐based thermal module can achieve the optimum heat dissipation and the maximum heat flux may exceed 90 W/cm2. Also, when copper fins are 3 mm in height, 0.2 mm in thickness, 53 in number and spaced out 1.0 mm apart, the optimum total thermal resistance of a vapour chamber‐based thermal module is 0.28 C/W.

Originality/value

The Sapphire Atomic HD3870 of Video Graphics Array module for AMD RV670XT using MicroLoops vapour chamber has greater thermal performance than the AMD reference dual slot thermal module. So, AMD latest GPU is considered to be the vapour chamber thermal cooler to solve the higher power consumption.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 March 1997

J.E. Ruckman

To clarify the principles and mechanisms of water vapour transfer by diffusion in waterproof breathable fabrics for clothing, experiments using a simple glass dish were…

Abstract

To clarify the principles and mechanisms of water vapour transfer by diffusion in waterproof breathable fabrics for clothing, experiments using a simple glass dish were carried out under steady state conditions with and without a temperature gradient in the climatic chamber. It was found that both vapour pressure and natural convection within the air gap affect water vapour transfer. The rates of water vapour transfer are ranked microfibre fabrics, cotton ventiles, PTFE‐laminated fabrics, poromeric polyurethane laminated fabrics, hydrophilic laminated fabrics, and polyurethane‐coated fabrics. In the presence of a temperature gradient, condensation was also found to be a major factor, especially at air temperatures below 0°C. Condensation occurred the least on the inner surface of PTFE‐laminated fabrics followed by cotton ventiles, microfibre fabrics, hydrophilic‐laminated fabrics, poromeric polyurethane‐laminated fabrics, and polyurethane coated fabrics.

Details

International Journal of Clothing Science and Technology, vol. 9 no. 1
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 17 January 2019

Lubomir Livovsky and Alena Pietrikova

The purpose of this paper is to investigate measurement and regulation of saturated vapour height level in vapour phase soldering (VPS) chamber based on parallel plate…

Abstract

Purpose

The purpose of this paper is to investigate measurement and regulation of saturated vapour height level in vapour phase soldering (VPS) chamber based on parallel plate capacitor and retaining a stable saturated vapour level above the boiling fluid, regardless of the quantity and size of assembled components.

Design/methodology/approach

Development and realisation of capacitance sensor that sensitively senses the maximum height level of saturated vapour above the boiling fluid in the VPS chamber was achieved. Methodology of measurement is based on capacitor change from single air to a parallel plate, filled with two dielectric environments in a stacked configuration: condensed fluid and vapour (air).

Findings

An easy air plate capacitor immersed in the saturated vapour above the boiling fluid can serve as a parallel plate capacitor owing to the conversion of the air to the parallel plate capacitor. A thin film of fluid between the two capacitor plates corresponds to the height of the saturated vapour, which changes the capacity of the parallel plate capacitor.

Originality/value

Introducing the capacitive sensor directly into the VPS work space allows to achieve a constant height level of saturated vapour. Based on the capacity change, it is possible to control the heating power. There is a lack of information regarding measurement of stable height of vapour in the industry, and the present article shows how to easily improve the way to regulate the bandwidth of saturated vapour in the VPS process.

Details

Soldering & Surface Mount Technology, vol. 31 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 4 October 2011

Wenfang Song and Weidong Yu

The purpose of this paper is to describe a new transient approach for testing water vapor diffusivity of fabrics and fibrous assemblies.

Abstract

Purpose

The purpose of this paper is to describe a new transient approach for testing water vapor diffusivity of fabrics and fibrous assemblies.

Design/methodology/approach

An apparatus was designed and built in order to investigate the transient water vapor diffusivity of fabrics and fibrous assemblies, and the apparatus is validated by applying a theoretical model and comparing the result obtained by the desiccant cup method.

Findings

The transient water vapor diffusion test method permits rapid testing of small quantities of fabrics in a short amount of time. The method has an excellent correlation and agreement with the desiccant cup method. The variation of the new method is much smaller than the desiccant method. It also provided a way to study water vapor transfer through fibrous assemblies.

Originality/value

The paper introduces a new approach for testing water vapor diffusivity of fabrics and fibrous assemblies.

Details

International Journal of Clothing Science and Technology, vol. 23 no. 5
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 1 October 2005

Rongdi Han, Junyan Liu and Yongfeng Sun

Nowadays, green cutting has become the focus because of its ecological problem and the necessary environment protection, so that the research on experimentation of green…

Abstract

Purpose

Nowadays, green cutting has become the focus because of its ecological problem and the necessary environment protection, so that the research on experimentation of green cutting with water vapor as coolant and lubricant is studied because water vapor has many benefits of cheapness, no pollution, no harm and no recycling and handling.

Design/methodology/approach

The vapor generator and the vapor feed system are manufactured, the distribution of temperature and velocity of vapor jet flow are simulated by MATLAB program, and under the conditions of compress air, oil water emulsion, water vapor as coolant and lubricant and dry cutting, respectively, the turning experimentation of comparison which the tool is YT15, and the working material is steel 45.

Findings

Water vapor, as coolant and lubricant, the cutting force is reduced, respectively about 30‐40, 20‐30 and 10‐15 percent by comparing to dry cutting, compressed air and oil water emulsion. The cutting temperature is, respectively about 30, 40 and 50 percent with the other conditions of dry cutting, compressed air and oil water emulsion. The friction coefficient and the chip deformation coefficient are correspondingly decreased and the surface roughness value has been diminished too. Through analysis of the experimental results, water vapor as coolant and lubricant possesses better lubricating action because of the excellent penetration performance and the low lubrication layer shearing strength of water vapor.

Originality/value

Water vapor as coolant and lubricant provides a novel method for realizing no contamination green cutting.

Details

Industrial Lubrication and Tribology, vol. 57 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 17 August 2010

Liu Junyan, Han Rongdi and Wang Yang

Green machining is becoming increasingly more popular due to concern regarding the safety of the environment and human health. The important implementation of stricter…

Abstract

Purpose

Green machining is becoming increasingly more popular due to concern regarding the safety of the environment and human health. The important implementation of stricter Environmental Protection Agency regulations associated with the use of ample amount of coolants and lubricants has led to this study on a new green machining technology with application of water vapor as coolants and lubricants in cutting Ni‐based superalloys and titanium alloy Ti‐6Al‐4V with uncoated carbide inserts (ISO Type K10). The purpose of this paper is to show that machining technology with application of water vapour could be an economical and environmentally compatible lubrication technique for machining difficult‐cut‐materials.

Design/methodology/approach

In this paper, the effect of water vapor applications in machining difficult‐cut‐materials have been investigated in detail, the cutting force, the chip deformation coefficient, the rake face wear and the width of tool flank land VB have been examined and analyzed, and a new green cutting technology is researched to machining Ni base superalloys and Ti‐6Al‐4V difficult‐cut‐materials.

Findings

The cutting force of machining Ni base superalloys and Ti‐6Al‐4V was affected by direct water vapor application, being lower than dry cutting and wet machining for all machining conditions; the Λh is the smallest with applications of water vapor as coolants and lubricants compared to dry cutting, pure water and oil water emulsion conditions the tool life extended by about six times than dry cutting, about four times than oil water emulsions at low cutting speed (νc<100 m/min), and about two‐four times than dry cutting, about two‐three time than oil water emulsions at higher cutting speed (νc>100 m/min) during machining Ti‐6Al‐4V with application of water vapor direct into the cutting zone.

Originality/value

The green cutting technology which applies water vapor as coolants and lubricants advocates a new method for machining difficult‐cut‐materials (Ni base superalloys and Ti‐6Al‐4V) without any environment pollution and operator health problem because the cutting force and chip deformation coefficient are reduced, the tool life is extended, and the tool flank wear can be decreased with applications of water vapor as coolants and lubricants to alleviate the adhering and diffusion wear compared to wet cutting and dry cutting.

Details

Industrial Lubrication and Tribology, vol. 62 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 2 October 2007

Liu Junyan, Han Rongdi and Zhang Li

At the present time, green cutting has become the focus of attention in ecological and environmental protection. Water vapor is cheap, pollution‐free and eco‐friendly…

Abstract

Purpose

At the present time, green cutting has become the focus of attention in ecological and environmental protection. Water vapor is cheap, pollution‐free and eco‐friendly. Therefore, it is a good and economical coolant and lubricant. To find the discipline of nozzle diameter, the parameters of water vapor jet flow and cooling distance influence on its lubricating action effect, experiments were carried out in which YT15 (P10 type in ISO) tool was used in cutting C45 steel.

Design/methodology/approach

The vapor generator and vapor feed system are manufactured. The temperature and velocity distribution of water vapor jet flow influences the velocity such that water vapor fills up the capillaries and forms the boundary lubricating film layer in the cutting zone, and the temperature and velocity distribution of the vapor jet flow section contains the effective area for the lubricating effect. Through the temperature distribution measured, the empirical formula of temperature distribution is obtained and simulated by Matlab. The turning experiment was carried out according to quantity in cutting υc=45, 60, 75, 90, 105, 120 mm/min, f=0.1 ∼ 0.3 mm/rev, ap=1, 2, 3, 3.5 mm and the jet flow parameters were changed, respectively.

Findings

It was found that: significant decrease of cutting force can be realized with reduced nozzle diameter, increased the sett pressure and shortened the cooling distance. However, reduced to a certain extent it will lead to the increase of the cutting force. The optimal nozzle diameter is 2 mm for the best lubricating effect. The effect on cutting force of the cooling distance is much better than the setting pressure. Significant decrease of friction coefficient of tool‐chip can be realized with reduced nozzle diameter. However, reduced to a certain extent it will lead to the increase of friction coefficient. Significant thinness of chips can be realized by reducing nozzle diameter. But if the diameter is reduced to a certain degree, chips will be thickened. Increased set pressure and shortened cooling distance can both reduce chip thickness, resulting in reduction of chip deformation coefficient. Since water vapor has the advantage of being cheap, pollution‐free and harmless, and there is no need for disposal and recycling, it is ideal for cooling and lubricating technology in green cutting.

Originality/value

The paper establishes the discipline of nozzle diameter, the parameters of water vapor jet flow and cooling distance influence on its lubricating action effect.

Details

Industrial Lubrication and Tribology, vol. 59 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 1 September 1995

Young Kag Kim and Sang Soo Kim

We present the equations for condensation in cooled upward laminar flowin tubes and consider their solution for low vapour concentrations andvariable vapour‐gas…

Abstract

We present the equations for condensation in cooled upward laminar flow in tubes and consider their solution for low vapour concentrations and variable vapour‐gas thermodynamic properties. We treated the full problem, including coupling with the aerosol size distribution, by using the PSI‐CELL (Particle Source in Cell) method. The particle trajectories start from the point where the particles are generated homogeneous nucleation. Particle size distribution and vapour scavenging by particles are obtained in forced convection and mixed convection regions. Calculations were also conducted with respect to tube diameters.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 5 no. 9
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 5 September 2016

Xiao-Qun Dai and George Havenith

The purpose of this paper is to investigate the effect of air and vapor permeability of jacket materials on ventilation, heat and moisture transfer.

Abstract

Purpose

The purpose of this paper is to investigate the effect of air and vapor permeability of jacket materials on ventilation, heat and moisture transfer.

Design/methodology/approach

Clothing ventilation (V), thermal insulation (I) and vapor resistance (R e ) of three jackets made of different materials (normal textile, PVC and “breathable” membrane coated textile), worn on an articulated thermal manikin in a controlled climate chamber, were measured under various conditions, respectively. The various conditions of microenvironment ventilation were created by making the manikin stand and walk, combined with three wind speeds of <0.2, 0.4 and 2.0 m/s, respectively.

Findings

In the condition without any forced convection, the air permeability makes no big difference to dry and evaporative heat transfer among the jackets, while the vapor permeability plays a big role in the evaporative heat loss. In the condition with forced convection, the dry heat diffusion is strongly coupled to the evaporative heat transfer in air and vapor permeable textile material.

Research limitations/implications

The effects of ventilation on heat and moisture transfer varies because of different ways of ventilation arising: penetration through the fabric is proven to be the most effective way in vapor transfer although it does not seem as helpful for dry heat diffusion.

Originality/value

The achievements in this paper deepens the understanding of the process of the dry and evaporative heat transfer through clothing, provides clothing designer guidance to choose proper materials for a garment, especially work clothing.

Details

International Journal of Clothing Science and Technology, vol. 28 no. 5
Type: Research Article
ISSN: 0955-6222

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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

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