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Abstract: In the present study it is shown that jet flows from innovative rectangular air diffusion grilles with lobed ailerons ensure higher mixing in a room than baseline jets from classical rectangular air diffusion grilles with straight ailerons. The experimental approach uses time resolved and classical large scale PIV measurements. The estimated entrainment in the case of the jet issued from the grille with lobed ailerons is found to be greater than in the case of the standard grille with straight ailerons. This way, lobed ailerons might be a solution for the optimization of air diffusion grilles in order to insure more uniform flows and to reduce thermal discomfort and draught sensation. An analysis of the phenomena being at the origin of this performance is proposed. The jet issued from an elementary slot with lobed geometry is compared to the linear slot jet. Based on the elementary slot jets analysis, it is shown that the vortical dynamics in the lobed flow is complex and is governed by large streamwise structures generated by the lobed nozzle lip. This explains the recorded performance in terms of induction and mixing. The special geometry of the lobed grille was not found to generate supplementary noise as the sound pressure levels were recorded for both grilles for different discharge flow rates. Pressure losses were also found to have similar values for both grilles. [ABSTRACT FROM AUTHOR]

Abstract: A passive chilled beam is a source of natural convection, creating a flow of cold air directly into the occupied zone. Experiments were conducted in a mock-up of an office room to study the air velocities in the occupied spaces. In addition, velocity profiles are registered when underneath heat loads exist and the cool and warm air flows interact. Experimental laboratory study revealed that in the case of the underneath heat gains, even no upward plume was generated and the dummy only acted as a flow obstacle, having a significant effect on the velocity profile. Furthermore, in an actual occupied office environment, the thermal plumes and the supply air diffuser mixed effectively the whole air volume. The maximum air velocity measured was still below 0.25m/s with the extremely high heat gain of 164W/m2. The results demonstrate that analysis methods were the interaction of convection flow and jet are not taken into account could not accurately describe air movement and draught risk in the occupied room space. [Copyright &y& Elsevier]

Abstract: The current density of biofuel cells which use dissolved O2 as electron acceptor is limited by O2 supply to the electrode surface due to the low solubility and small diffusion coefficient of O2 in the electrolyte solution. In order to increase the current density, we constructed an air diffusion biocathode which uses O2 directly from the air. As cathodic biocatalyst, we utilized CueO from Escherichia coli, which belongs to the family of multi-copper oxidases. O2 reduction was catalyzed by CueO adsorbed on Ketjen black-modified carbon paper electrodes. The hydrophobic electrode surface was obtained by optimizing the weight ratio of polytetrafluoroethylene binder to Ketjen black. The current density of O2 reduction reached values as high as 20 mA cm−2 at 0 V vs. Ag|AgCl, KCl(sat.) in a citrate buffer (1.0 M, pH 5.0, 25 °C). [Copyright &y& Elsevier]

In melt blowing, microfibrous nonwoven material is manufactured by using high-speed air to attenuate polymer melt. The melt-blown air jet determines the process of polymer attenuation and fiber formation. In this work, the importance of lateral velocity on the fiber was first theoretical verified. The lateral diffused characteristic of the air flow field in slot-die melt blowing was researched by measuring the velocity direction using a dual-wire probe hot-wire anemometer. Meanwhile, the fiber path was captured by high-speed photography. Results showed that there existed a critical boundary of the lateral diffusion, however, air jets in the x–z plane are a completely diffused field. This work indicates that the lateral velocity in the y–z plane is one of the crucial factors for initiating fiber whipping and fiber distribution. [ABSTRACT FROM AUTHOR]