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In this paper, a single module of cross-flow membrane humidifier is evaluated as a three-dimensional multiphase model. The purpose of this paper is to analyze the effect of volume flow rate, dry temperature, dew point wet temperature and porosity of gas diffusion layer on the humidifier performance.

In this study, one set of coupled equations are continuity, momentum, species and energy conservation is considered. The numerical code is benchmarked by the comparison of numerical results with experimental data of Hwang et al.

The results reveal that the transfer rate of water vapor and dew point approach temperature (DPAT) increase by increasing the volume flow rate. Also, it is found that the water recovery ratio (WRR) and relative humidity (RH) decrease with increasing volume flow rate. In addition, all mixed results decrease with increasing dry side temperature especially at high volume flow rates and this trend in high volume flow rates is more sensible. Although the transfer rate of water vapor and DPAT increases with increasing the wet inlet temperature, WRR and RH reduce. Increasing dew point temperature effect is more sensible at the wet side is compared with the dry side. The humidification performance will be enhanced with increasing diffusion layer porosity by increasing the wet inlet dew point temperature, but has no meaningful effect on other operating parameters. The pressure drop along humidifier gas channels increases with rising flow rate, consequently, the required power of membrane humidifier will enhance.

According to previous studies, the three-dimensional numerical multiphase model of cross-flow membrane humidifier has not been developed.

This paper aims to investigate the effect of partially blocking the cathode channel with the stair arrangement of obstacles on the performance of a proton exchange membrane fuel cell.

A numerical study is conducted by developing a three-dimensional computational fluid dynamics model.

As the angle of the stair arrangement increases, the performance of the fuel cell is reduced and the pressure drop is decreased. The use of four stair obstacles with an angle of 0.17° leads to higher power density and a lower pressure drop compared to the case with three rectangular obstacles of the same size and maximum height. The use of four stair obstacles with an angle of 0.34° results in higher power density and lower pressure drop compared to the case with two rectangular obstacles of the same size and maximum height.

Using the stair arrangement of obstacles as an innovation of the present work, in addition to improving the fuel cell’s performance, creates a lower pressure drop than the simple arrangement of obstacles.

The aim of this study is to compare the effects of Sanosil and glutaraldehyde 2 percent in disinfecting ventilator connecting tubes in an intensive care unit (ICU) environment.

The 12‐week open‐labelled clinical trial was conducted in the surgical ICU of a teaching hospital from March to May 2005. In the first phase of the study, high level disinfection was performed using glutaraldehyde 2 percent, whereas Sanosil was used as the disinfectant agent of the second phase. Samples for microbial culture were obtained from the Y piece, the expiratory limb proximal to the ventilator and the humidifier in different stages; the results were then compared.

Positive culture was more frequently reported in Y pieces, humidifiers and expiratory end of ventilators. Comparing the two groups, there were more positive cultures in the glutaraldehyde group (p value=0.005); multiple organism growths, gram negative, gram positive and fungi were also more frequent in this group (p value=0.01; 0. 007; 0. 062; 0.144, respectively).

The paper shows that Sanosil is an effective agent in reducing the contamination risk in the tubes used in ICUs.

The bulk batch fabrication process of thick film technology has been utilised in the design and production of miniature amperometric dissolved oxygen sensors based on potentiostatic and voltammetric operation. Three different polymers have been investigated as membrane materials – cellulose acetate, PTFE and PVC. PTFE has been deposited on the devices by aerosol spray and PVC and cellulose acetate by screen‐printing. These methods have been shown to be effective membrane fabrication techniques, and have significant implications in the field of chemical sensors as a whole. All the membrane covered devices investigated were found to exhibit sensitive and linear responses to dissolved oxygen. The effects of temperature and flow rate on sensor response have been investigated and the use of PVC and PTFE in place of cellulose acetate have been shown to reduce both effects. These membranes have also been shown to reduce the detrimental effects of fouling observed on the surfaces of cellulose acetate covered devices as they are powered in tap water.

The purpose of this paper is to investigate the effects of hydrogen humidity on the performance of air-breathing proton exchange membrane (PEM) fuel cells.

An efficient mathematical model for air-breathing PEM fuel cells has been built in MATLAB. The sensitivity of the fuel cell performance to the heat transfer coefficient is investigated first. The effect of hydrogen humidity is also studied. In addition, under different hydrogen humidities, the most appropriate thickness of the gas diffusion layer (GDL) is investigated.

The heat transfer coefficient dictates the performance limiting mode of the air-breathing PEM fuel cell, the modelled air-breathing fuel cell is limited by the dry-out of the membrane at high current densities. The performance of the fuel cell is mainly influenced by the hydrogen humidity. Besides, an optimal cathode GDL and relatively thinner anode GDL are favoured to achieve a good performance of the fuel cell.

The current study improves the understanding of the effect of the hydrogen humidity in air-breathing fuel cells and this new model can be used to investigate different component properties in real designs.

The hydrogen relative humidity and the GDL thickness can be controlled to improve the performance of air-breathing fuel cells.

At the Royal Society of Health annual conference, no less a person than the editor of the B.M.A.'s “Family Doctor” publications, speaking of the failure of the anti‐smoking campaign, said we “had to accept that health education did not work”; viewing the difficulties in food hygiene, there are many enthusiasts in public health who must be thinking the same thing. Dr Trevor Weston said people read and believed what the health educationists propounded, but this did not make them change their behaviour. In the early days of its conception, too much was undoubtedly expected from health education. It was one of those plans and schemes, part of the bright, new world which emerged in the heady period which followed the carnage of the Great War; perhaps one form of expressing relief that at long last it was all over. It was a time for rebuilding—housing, nutritional and living standards; as the politicians of the day were saying, you cannot build democracy—hadn't the world just been made “safe for democracy?”—on an empty belly and life in a hovel. People knew little or nothing about health or how to safeguard it; health education seemed right and proper at this time. There were few such conceptions in France which had suffered appalling losses; the poilu who had survived wanted only to return to his fields and womenfolk, satisfied that Marianne would take revenge and exact massive retribution from the Boche!

The purpose of this study is simulation of of polymer electrolyte membrane fuel cell. Proton-exchange membrane fuel cells are promising power sources for use in power plants and vehicles. These fuel cells provide a high level of energy efficiency at low temperature without any pollution. The convection inside the cell plays a key role in the electrochemical reactions and the performance of the cell. Accordingly, the transport processes in these cells have been investigated thoroughly in previous studies that also carried out functional modeling.

A multi-phase model was used to study the limitations of the reactions and their impact on the performance of the cell. The governing equations (conservation of mass, momentum and particle transport) were solved by computational fluid dynamics (CFD) (ANSYS fluent) using appropriate source terms. The two-phase flow in the fuel cell was simulated three-dimensionally under steady-state conditions. The flow of water inside the cell was also simulated at high-current density.

The simulation results suggested that the porosity of the gas diffusion layer (GDL) is one of the most important design parameters with a significant impact on the current density limitation and, consequently, on the cell performance.

This study was mainly focused on the two-phase analysis of the steady flow in the fuel cell and on investigating the impacts of a two-phase flow on the performance of the cell and also on the flow in the GDL, the membrane and the catalyst layer using the CFD.

This paper aims to determine the optimum arrangement of a reverse osmosis system in two methods of plug and concentrate recycling.

To compare the optimum conditions of these two methods, a seawater reverse osmosis system was considered to produce fresh water at a rate of 4,000 m3/d for Mahyarkala city, located in north of Iran, for a period of 20 years. Using genetic algorithms and two-objective optimization method, the reverse osmosis system was designed.

The results showed that exergy efficiency in optimum condition for concentrate recycling and plug methods was 82.6 and 92.4 per cent, respectively. The optimizations results showed that concentrate recycling method, despite a 36 per cent reduction in the initial cost and a 2 per cent increase in maintenance expenses, provides 6 per cent higher recovery and 19.7 per cent less permeate concentration than two-stage plug method.

Optimization parameters include feed water pressure, the rate of water return from the brine for concentrate recycling system, type of SW membrane, feedwater flow rate and numbers of elements in each pressure vessel (PV). These parameters were also compared to each other in terms of recovery (R) and freshwater unit production cost. In addition, the exergy of all elements was analyzed by selecting the optimal mode of each system.