Reducing running costs in air conditioningRéduire les coûts de fonctionnement en conditionnement d'air

Previous studies using wide-boiling refrigerant mixtures were reported in the literature as a method of reducing power consumption in air conditioning. A novel air conditioning test unit incorporating this concept was tested at the Department of Chemical Engineering at Leeds University. Experimental tests with a refrigerant mixture, R407C, produced COPs in excess of 4. Also, a simulation program was used to model the behaviour of other mixtures. It yielded a COP of about 5 for mixture R32/R134a. A financial study was made to calculate the total annual costs of a unit using R32/R134a. It showed that annual savings of up to 41 per cent were possible compared to a unit using R134a.     

利用立辊轧机实现钢板平面形状控制

为改善中厚板平面形状,有效控制窄板坯轧制宽中厚钢板的鼓形度,减少切边,切头尾损耗,秦皇岛首钢板材有限公司开发了立辊轧制新工艺,对板坯头尾和边部进行修正轧制,改善了钢板平面形状,减少了切损,综合成材度提高1．5％－3．0％     

Study on ice slurry production by water spray

A theoretical and experimental study was performed to examine the water spray method of ice slurry production. First, the conditions for the formation of ice particles were investigated theoretically by the diffusion-controlled evaporation model. The prediction of the model was proved to agree relatively well with experiments in which we examined the conditions for a droplet of initial temperature 20°C and size 50 μm to change into an ice particle in a chamber of height 1.33 m. Second, the production of cold storage heat will increase almost proportionally to the number of spray nozzles because no substantial difference was found in the Sauter Mean Diameter (SMD) of sprays from single and twin nozzle. Third, an ice slurry was experimentally obtained by spraying droplets of 7% ethylene glycol aqueous solution in a vacuum chamber where pressure is maintained below the freezing point of the solution. Finally, based on the theoretical and experimental results, we propose an optimizing chart for providing the operating conditions to make ice slurry using the relations of the staying time of the droplet in the chamber, the injection pressure, the spray droplet size and the chamber pressure.     

Environmental and biological responses of former channels to river incision: A diachronic study on the upper rhǒne river

The impacts of river incision should be a lowering of the river level, which would increase the rate of water flow from the hillslope aquifer to the river and its former channels. If this aquifer is nutrient-poor, it should favour the oligotrophication of the former channels. However, if the lowering of the water-table exceeds the depth of the former channels, then it should lead to the drainage of these channels. These hypotheses were tested on two former channels located in a degrading reach of the Rhǒne River (France); the former channels were influenced by floods, seepage water from the river and hillslope groundwater in 1989. The rate of river incision in this reach has increased since 1980 because of gravel extraction from the river bed (0.5 m between 1989 and 1993). Between 1989 and 1993, the reduction of river infiltration and the increase in the amount of water from the hillslope aquifer in the former channels were demonstrated by the decrease in the phosphate and ammonia content of the water, and its increased alkalinity and conductivity. The responses of aquatic vegetation to river incision depended on the vegetation zone investigated. Two floristic zones that were frequently flooded and species-poor in 1989 remained species-poor in 1993. Two floristic zones, which were species-rich and patchily organized, became dry or very shallow in 1993; as a consequence, aquatic vegetation disappeared, and was replaced by helophytes and terrestrial species. In the last vegetation zone, the increase in the amount of water coming from the hillslope aquifer caused the appearance and development of Chara hispida, an oligotraphent species. Unforeseen impacts of river incision were a decrease in the spatial and temporal heterogeneity of the former channels and lower aquatic macrophyte richness.     

20世纪初中国女子美术留学教育

众所周知,20世纪前期在中国历史上出现了规模宏大的留学热潮。其中,女子留学研习美术,是中国近现代美术教育史上一个不可忽视的现象。她们或留学日本,或留学欧美,主动引进传播西方美术,为中国美术走向多元化、中西兼容的开放时代立下了不朽的功绩。     

Inhibition de l'action phototoxique du bergaptène par des filtres UV-A

Il est bien acquis que le 5-méthoxypsoralène (5-MOP, bergaptène) contenu dans l'essence de bergamote exerce plusieurs actions biologiques à la suite d'irradiation en lumière UV-longue (UV-A, λ > 320 nm). Cette étude a eu pour but de vérifier si la réponse phototoxique, déclenchée chez le cobaye à la suite d'application cutanée de 5-MOP suivie par rayonnement UV, peut être réduite ou même annulée par l'application simultanée de substances absorbant les rayons UV-A. Les solutions photosensibilisatrices employées étaient (a) une solution alcoolique de 5-MOP, (b) de l'essence de bergamote diluée, et (c) un parfum expérimental. Parmi les filtres qui ont été essayés, deux dérivés du dibenzoylméthane se sont révelés particulièrement efficaces. On a observé que l'activité protectrice de ces filtres augmente de façon significative lorsqu'ils sont dissous dans l'essence de bergamote, ou dans le parfum, par rapport à l'activité demontrée dans la solution alcoolique de 5-MOP. Un dérivé du distirylbiphényle possédant un maximum d'absorption à 350 nm s'est révelé particulièrement actif.
Inhibition of bergaptene toxicity by UV-A filters     

Condensation heat transfer coefficients of halogenated binary refrigerant mixtures on a smooth tube

In this study, external condensation heat transfer coefficients (HTCs) of nonazeotropic refrigerant mixtures of HFC32/HFC134a and HFC134a/HCFC123 at various compositions were measured on a horizontal smooth tube of a 19 mm outside diameter. All data were taken at the vapor temperature of 39 °C with a wall subcooling of 3–8 °C. Test results showed that HTCs of the tested mixtures were 19.4–85.1% lower than the ideal values calculated by the mole fraction weighting of the HTCs of the pure components. A thermal resistance due to the diffusion vapor film seemed to be partly responsible for the significant reduction of HTCs with these nonazeotropic mixtures.     

Ice formation of aqueous solution and its removal phenomena around vertical cooled cylinder

Experimental and analytical studies for freezing phenomena of ethylene glycol solution around a vertical cooled polyvinyl-chloride cylinder have been performed. It is found that the crystal ice formed around the vertical cylinder is removed from the cylinder surface due to a buoyancy force acting on the crystal ice. The crystal ice slides along the cylinder surface due to buoyancy force and grows in the shape of a tube by joining with the neighboring ice. It is shown that the onset of ice removal condition is related to the heat flux ratio, ‘from the cylinder surface into the cylinder’ to ‘from the cylinder surface into the solution’. The ice removal occurs more easily for short cylinders than for long ones.     

Effect of reduction rate and annealing temperature on texture evolution and magnetic properties of used non-oriented silicon steel

This paper discusses the method of improving the magnetic properties of used silicon steel by cold rolling and annealing process with used non-oriented silicon steel as the object. The texture evolution and magnetic domain structure are also investigated. Experimental results show that the magnetic domain can be transformed vastly compared with the used silicon steel when the specimens are prepared through the same cold rolling and annealing conditions. The length of the magnetic wall and the density of magnetic domain per unit area are boosted, and the magnetic domain refinement is exceedingly apparent. Under the same annealing condition (at 950 °C for 5 min), the γ-fiber is gradually decreased to 6.6 % and the {110} recrystallization texture is gradually enhanced with increased reduction from 28.3 % to 40 %. The intensity of the Goss texture reaches a maximum of 22.2. For the cold rolling reduction of 34.3 %, the γ-fiber gradually decrease to 13.8 % and the {110} recrystallization texture is gradually enhanced with increase in the annealing temperature from 800 °C to 950 °C. Moreover, the intensity of Goss texture reaches 14. The sample prepared through 40 % reduction and annealing at 950 °C for 5 min exhibited the most desirable magnetic properties. The magnetic induction B₅₀ value of the specimen is increased by 0.052 T, and the core loss P_1.5/50 is reduced by 0.478 W/kg compared with the initial specimen.