Temperature distribution within a ceiling jet propagating in an inclined flat-ceilinged tunnel with natural ventilation

In this study, we conducted detailed measurements of the temperature distribution within a steady fire-driven ceiling jet, formed in a tunnel with a rectangular cross-section. We then compared the measured temperature distributions with those for an unconfined smooth-ceiling jet flow, and estimated the relative errors between them. The results showed that the temperature distribution in a horizontal tunnel exhibits a greater bulge than that of a ceiling jet under an unconfined ceiling and varied from a bulging shape to an exponential shape as the tunnel inclination increased. We propose a new correlation for representing the temperature distribution, which takes the tunnel inclination into account, and which consists of an exponential function and a cubic function with a coordinated transformation.     

Ceiling mounted personalized ventilation system in hot and humid climate—An energy analysis

This study is to evaluate energy saving potential of ceiling mounted personalized ventilation (PV) system in conjunction with background mixing ventilation compared with mixing ventilation system alone and with mixing ventilation system when occupants are provided with individually controlled desk fans for generating additional air movement at each desk. Control strategy applied includes different number of personalized ventilation air terminal devices used and different PV airflow rates supplied. Energy calculation is based on design conditions in Singapore, representing a hot and humid climate. The results reveal that increasing room temperature can save cooling energy when the combination of PV with ceiling mounted personalized ventilation nozzles and background mixing ventilation is used. In this case the energy for transport of air increases but the total energy decreases, i.e. energy can be saved due to elevated room temperature. Comparing with mixing ventilation plus desk fans, ceiling mounted personalized ventilation cannot only realize better cooling effect but also decrease the total energy consumption.     

An investigation of air inlet types in mixing ventilation

Previous studies have shown that dispersion of contaminant concentrations strongly depends on air inlet types. However, these studies were performed computationally, not experimentally. Thus, the purpose of the current research is to obtain contaminant concentrations in a room, to perform qualitative and quantitative comparison for a wall jet (WJ) air inlet and a ceiling diffuser (CD) air inlet, and to determine more efficient inlet and outlet configuration.     

Critical ventilation velocity for tunnel fires occurring near tunnel exits

Ventilation is an effective method for controlling smoke during a tunnel fire. The “critical ventilation velocity” u_cr is generally defined as the minimum velocity at which smoke is prevented from spreading against the longitudinal ventilation flow in tunnel fire situations. This study conducted small-scale experiments to investigate u_cr for situations when tunnel fire occurs near tunnel exits. The model tunnel was 4 m long, 0.6 m wide and 0.6 m tall, and the fires were located at 0.5 m, 1.0 m and 1.5 m from the tunnel exit. 6.3×6.3 cm² and 9.0×9.0 cm² square asoline fuel pans were used as fire source. Results show that u_cr decreases as the fire approaches the tunnel exit.     

积木式推土机驾驶室设计

对积木式推土机驾驶室设计作了简单介绍。论述了驾驶室主体和顶棚的改进措施。     

国内外大型低温冷藏库氨制冷系统和制冷设备节能及安全技术的发展趋势

近年来国内外冷冻冷藏行业针对不同的冷库形式和贮藏用户特点,在低温冷藏库氨制冷系统和制冷机器、设备采用一些节能及安全技术。本文根据我国的国情和国外先进国家氨制冷系统的发展趋势做出一些研究和对比。     

Experimental study on elevated fires in a ceiling vented compartment

The impacts of elevation on fires in a ceiling vented compartment were investigated experimentally. The flame behavior of elevated fires was recorded. Various parameters including the fuel mass loss rate, the light extinction coefficient, the oxygen concentration and the gas temperature were measured. Results indicated that the variations of the flame behavior were consistent with that of the fuel mass loss rate. The fire location significantly impacted the light extinction coefficient, the oxygen concentration and the gas temperature, which all showed distinct stratification phenomena. For a higher elevated fire, the average fuel loss rate and the overall light extinction coefficient were smaller, the oxygen concentration was higher and the gas temperature was lower. In addition, the smoke descending was slower. From the perspective of those parameters the fire was less hazardous if the fire was elevated higher, which was totally different from the elevated fires in closed compartments.     

健康环保汽车内饰面料的研究与产品开发

基于汽车健康座舱概念及其评价维度,提出健康环保内饰面料产品的开发思路,环保内饰面料主要从纤维材料和技术工艺的角度去考虑,健康功能内饰面料通过创新功能材料的应用和功能整理技术赋予内饰面料附加的健康功能价值。并以抗菌三防健康功能顶棚面料的开发为例,测试其抗菌、防水、防污性能。提出健康安全、绿色环保、雅致舒适、时尚高性能、智能高品质的智慧健康座舱,将成为未来汽车内饰设计开发的重要方向。