建筑物水冷却防火技术的研究与应用

<正> 早在上一世纪,曾有人建议使用水冷却技术进行钢结构防火。但这项技术到本世纪六十年代才在建筑实践中得到应用。使用水冷却防火技术时,被保护的结构构件须制成空心型材,管内充水。遇到火灾时,水升温汽化,排出热量。为了确保冷却,水必须在系统中循     

夏季柴油机使用冷却系统的保养

<正>拖拉机在田间作业时,没有多长时间,柴油机温度便迅速升高,柴油机温度过将使机油变稀、润滑性能降低等,在夏季做好冷却系统的保养工作显得特别重要。一、冷却系统的组成及功用柴油机的冷却系统按散热方式不同可分为空气冷却和水冷却两种。拖拉机采用水冷却。水冷却系统一般由风扇、散热器、水泵、水温表、调温器、水     

关于炼铁高炉冷却方式的几点体会

介绍了炼铁高炉的冷却方式，并对各方式的冷却原理、优缺点进行了分析比较，着重论述了汽化冷却的过程，指出汽化冷却是大中型高炉炉体冷却方式的发展方向。     

用水器具节水技术的发展

居民用水在城市用水中占有很大比率，大力推广节水技术，普及使用节水器具，对促进水资源的可持续发展和循环利用，缓解水资源紧缺，城市供水紧张，具有重要的意义。     

提高空气冷却系统的效率实现对多年冻土地区地基温度的控制(英文)

通过数学建模的方法调查在建筑工地上对地基土在冬季除雪和在夏季使用热绝缘层来提高空气冷却系统的可能性。同时表明,在建筑工地上对地基土在冬季除雪和在夏季使用热绝缘层对提高系统空气冷却整体性能的相对贡献度上在不同阶段是不同的。在土壤冷却第三阶段末期,清除积雪和使用热绝缘层不仅导致基础温度下降,而且对基础温度随深度再分配产生重要影响。计算结果清楚地表明,除雪和使用热绝缘覆盖物能增加空气冷却系统的效率,甚至可以从本质上降低其活性。     

某型民用飞机使用冷却方案降低机身内燃油箱可燃性的研究

本文对民机降低燃油箱可燃性背景进行了介绍,提出了使用换热器利用冲压空气冷却机身内油箱燃油的冷却方案,并对冷却方案对机身内油箱油温冷却效果进行分析,进而经过可燃性分析,使用冷却方案可以有效降低机身内油箱可燃性暴露率,为民机机身内油箱降低可燃性提供了新的思路。     

射水冷却对纤维混凝土耐高温性能的影响

对普通混凝土、镀铜微丝钢纤维混凝土、纤维素纤维混凝土进行200℃、400℃、600℃、800℃的高温作用,然后对高温试件分别进行自然冷却和射水冷却,得到了三种混凝土在不同温度、不同冷却方式下的质量损失率、残余抗压强度以及表观损伤指标。对比研究表明,在射水冷却条件下,普通混凝土和纤维素纤维混凝土的残余抗压强度相比较自然冷却有明显的下降,其中纤维素纤维混凝土在600℃下降了24.2%,800℃的普通混凝土在射水冷却过程中发生了爆炸,对现实火灾扑救极为不利,而射水冷却对钢纤维混凝土的影响不明显,残余抗压强度与自然冷却试件基本相同。     

海河水冷却应用

海河水冷却应用１概况海河沿岸各工厂企业，借地势之便使用河水进行生产的历史久长，取水便易、经济低廉，确曾施惠一方，造福于津门。但由于海水倒灌，河水有害物质增加，未经处理直接将河水用于生产，带来了诸多弊端。如天津碱厂３．２ｍ碳化塔使用河水冷却，夏季冷却水...     

烧制卫生陶筑的辊道窑

意大利莫里公司新研制出烧制卫生陶瓷的辊道窑。该窑分为四个部分:预热带、烧成带、自然空气冷却带和强制空气冷却带。烧成带包括微机控制装置、调节器、中速烧嘴,其中中速烧嘴安装在辊子上下两侧。烧嘴中所用的助燃空气来自冷却带。微机自动控制制品快速冷却,将过热气体和两侧的冷空气     

冷却方式和高温对混凝土劈裂抗拉强度影响

高温下混凝土结构在消防射水扑救时的力学性能会严重恶化,特别是其抗拉强度的降低尤为显著。为了深入研究不同高温、不同冷却方式对混凝土材料的劈裂抗拉强度的影响,对工程中常用的强度等级为C35的商品混凝土试件进行300,600,800℃高温加热,并分别采用自然冷却和水冷却两种方式降温,观察分析试件的物理化学变化规律及其原因。再将试件静置3周以上,分别进行巴西圆盘劈裂试验。研究结果表明:水冷却和高温对混凝土试件物理化学特性及劈裂抗拉强度影响很大,而且随着温度升高这种影响比自然冷却时更为明显,主要表现在当加热温度超过300℃后,水冷却造成的拉伸强度下降程度明显大于自然冷却的试件。在试验研究结果基础上,建立了考虑冷却方式影响的三段式温度-冷却损伤演化方程,并确定出相应的特征参数。     

Investigation of a hybrid system of nocturnal radiative cooling and direct evaporative cooling

In this paper, the results of a study on a hybrid system of nocturnal radiative cooling, cooling coil, and direct evaporative cooling in Tehran have been discussed. During a night, the nocturnal radiative cooling provides required chilled water for a cooling coil unit. The cold water is stored in a storage tank. During eight working hours of the next day, hot outdoor air is pre-cooled by means of the cooling coil unit and then it enters a direct evaporative cooling unit. In this period, temperature variation of the conditioned air is investigated. This hybrid system complements direct evaporative cooling as if it consumes low energy to provide cold water and is able to fulfill the comfort condition whereas direct evaporative alone is not able to provide summer comfort condition. The results obtained demonstrate that overall effectiveness of hybrid system is more than 100%. Thus, this environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems.     

Experimental study of cooling effects of a passive evaporative cooling wall constructed of porous ceramics with high water soaking-up ability

As a passive cooling strategy aimed at controlling increased surface temperatures and creating cooler urban environments in summer, the authors developed a passive evaporative cooling wall (PECW) constructed of porous ceramics. These ceramics possess a capillary force to soak water, which means that their vertical surface is wet up to a level higher than 100 cm when their lower end is placed in water. The present paper describes an experiment that clarifies the cooling effects of a prototype PECW constructed of pipe-shaped ceramics. The PECW is capable of absorbing water and allows wind penetration, thus reducing its surface temperature by means of water evaporation. Passive cooling effects such as solar shading, radiation cooling, and ventilation cooling can be enhanced by incorporating PECWs into the design of outdoor or semi-outdoor spaces in parks, pedestrian areas and residential courtyards. The following findings were understood from an experimental data collected over a summer period. Wet vertical surfaces of the ceramic pipe reached a height of over 1 m at an outdoor location exposed to solar radiation. Wet surface conditions can be maintained throughout successive sunny days during summer. A slight difference in the vertical surface temperatures of the ceramic pipe was found. The air passing through the PECW was cooled, and its temperature can be reduced to a minimum value by several degrees during summer daytime. It was also found that the surface temperature of the shaded ceramic pipe can be maintained at a temperature nearly equal to the wet-bulb temperature of outdoor air.     

Application of radiant cooling as a passive cooling option in hot humid climate

In hot and humid region, air-conditioning is increasingly used to attain thermal comfort. Air-conditioning is highly energy intensive and it is desirable to develop alternative low-energy means to achieve comfort. In a previous experimental investigation using a room equipped with radiant cooling panel, it was found that cooling water kept to 25 °C could be used to attain thermal comfort under some situations, while water at such temperature would not cause condensation of moisture from air on the panel. This paper reports results of a series of whole-year simulations using TRNSYS computer code on applications of radiant cooling to a room model that represents the actual experimental room. Admitting the inability of radiant cooling to accept latent load, chilled water at 10 °C was supplied to cooling coil to precool ventilation air while water cooled by cooling tower was used for radiant cooling in daytime application. For night-time, cooling water from cooling tower supplied for radiant cooling was found to be sufficient to achieve thermal comfort. Such applications are considered to be more amenable to residential houses.     

风冷制冷机的应用

分析了风冷制冷机的特点，认为风冷制冷机与水冷制冷机耗能相近，因无冷却塔和冷却水系统，使整个系统简单，占地少，指出风冷制冷机可用于我国长江以南地区，并特别适宜于超高层建筑。     

溶液除湿技术蒸发冷却空调系统探讨

本文介绍了溶液除湿与蒸发冷却技术相结合的蒸发冷却新风空调集成系统,氯化锂溶液作为除湿溶液。并详细介绍了其流程,探讨了这一系统特性以及调节方法。以南京夏季室外环境为例,进行实例计算。研究表明,该系统的COP可达0.92,具有良好的发展潜力与应用价值。     

蒸发式冷气机性能参数的试验研究

在改造后的风管式焓差法试验台上对样机进行了热工性能试验。试验分两个阶段:将喷淋水温度设定为进口空气湿球温度,试验研究不同空气流速和水汽比对阻力和效率的影响,得出最佳空气流速和水汽比;在此基础上测试喷淋水温度对水蒸发冷却器效率的影响。试验数据的整理与分析结果表明,最佳迎面空气流速为1.0m/s,最佳水汽比为0.1,蒸发冷却效率和显热制冷量随着喷淋水温度的升高而降低。根据冷气机制冷量实测值不低于明示值95%的规定,经计算得出,喷淋水温度的波动范围为20.13～25.86℃。     

再循环蒸发冷却中再循环风量的实验研究

介绍了一种再循环蒸发冷却技术,其原理是利用一部分经间接冷却处理的空气作为二次空气直接蒸发制取冷水,用冷水反过来间接冷却室外空气。搭建了相应的实验台,针对夏季实际工况条件,实验研究了再循环风量比例对蒸发冷却效率的影响,给出了合适的再循环风量范围。     

国内外蒸发冷却空调技术研究进展(3)

介绍了多级蒸发冷却空调系统、除湿与蒸发冷却相结合的空调系统、半集中式蒸发冷却空调系统、建筑物被动蒸发冷却技术、蒸发冷却自动控制系统及蒸发冷却水的水质处理。     

A two-stage system of nocturnal radiative and indirect evaporative cooling for conditions in Tehran

In this paper, the results of an investigation on a two-stage cooling system have been studied. This system consists of a nocturnal radiative unit, a cooling coil, and an indirect evaporative cooler. During the night in summer, requisite chilled water for a cooling coil unit is provided by nocturnal radiative cooling and is stored in a storage tank. During the next day, the water in the tank provides chilled water for the cooling coil unit and hot outdoor air passes through two-stages: the cooling coil unit and an indirect evaporative cooler. Three sources provide secondary air for the indirect evaporative cooler. The sources are outdoor air, the air leaving from the cooling coil, and the air leaving from the indirect stage (regenerative). The investigation has been conducted in weather conditions in the city Tehran. The results obtained demonstrate that the first stage of the system increases the effectiveness of the indirect evaporative cooler. Also, the regenerative model provides the best comfort conditions. Therefore, this environmentally friendly and energy-efficient system can be considered as an alternative to the mechanical vapor compression systems.     

冷却吊顶供水方式对系统运行能耗的影响

通过对冷却吊项运行能耗的计算机动态模拟，分析了供水方式、新风系统形式、冷却塔供冷、制冷机冷水温差等因素对系统能耗的影响，认为采用冷却吊项水系统与新风系统独立的水系统形式，并结合冷却塔自然供冷，节能效果最好。建议生产厂家开发小温差、大流量、低流动阻力的冷水机组，以推动冷却吊项的应用。