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《建筑热能通风空调》2016,(3)
本文对上海某地铁检修库三种不同通风模式(分别为机械排风+100%自然补风、机械排风+80%机械进风、壁式送排风机+无风管诱导风机三种通风方案)下库内气流组织进行模拟计算,通过分析Z=1.6 m成年男子呼吸区平面的速度分布和平均空气龄分布来比较不同方案的通风效果,并对各通风方案作动态经济分析,计算并比较了各方案的费用年值。结果表明,在换气次数为2次/时,检修库采用第三种通风方案(即采用壁式送、排风机+无风管诱导风机的设计)时气流平均速度较大,平均空气龄较低,通风效果较好。经济性分析表明第三种通风方案的费用年值也较低,且无论是初投资还是年运行维护费用均低于另两种方案,经济上也占有较大优势。 相似文献
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以海口市天翔路综合管廊燃气独立舱为研究对象,采用ANSYS ICEM CFD 15. 0软件在燃气管道上方建立二维物理模型,模型尺寸为200 m×2 m,泄漏孔为直径为5 mm的圆形小孔。燃气在独立舱室内的泄漏扩散满足三大守恒方程(质量守恒、动量守恒、能量守恒)、无化学反应的组分输运方程以及混合气体密度方程,采用Fluent 15. 0软件对燃气管道在事故通风状态下的泄漏扩散浓度分布规律及通风稀释效率的影响因素进行模拟研究。每种工况模拟开始时,将送风口风速设定为1. 87 m/s,即通风换气次数为6次/h,当位于下风向、距离泄漏孔15 m处的监测点报警后,暂停计算,重新设置边界条件,将送风口边界条件由正常通风换气次数调整为不同的事故通风换气次数,即改变送风口的风速,进行模拟研究。研究结果表明:当泄漏孔径不超过5 mm,管道压力不超过0. 4 MPa时,12次/h的最小事故通风可以满足综合管廊内燃气舱室的安全运行。当泄漏孔径为5 mm、管道压力为0. 8 MPa时,24次/h的换气次数基本满足燃气舱的通风换气需求。管道压力越大,泄漏量越大,燃气舱解除危险所需的通风换气量也越大,因此建议以管道压力及舱室燃气浓度为耦合函数,采用变频风机,实现事故状态下联动通风控制。燃气管道发生泄漏时,增加通风换气次数可以明显地稀释舱室内的燃气至报警浓度以下,但是通风口至防火墙之间的角落里容易积聚泄漏的天然气,因此,建议在燃气舱每个防火分区的排风口和舱室右侧防火墙之间的死角区域增加诱导风机。 相似文献
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介绍了综合医院的门诊部、住院部、医技部及中心供应部等主要部门的通风系统的形式、换气次数及正负压要求.探讨了通风系统的划分、风机噪声的控制和过滤器的选择等设计中需要注意的问题. 相似文献
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为了解新建住宅在不同封闭状态下的换气次数及测量换气次数的影响因素。以 CO2 作为示踪气体,用示踪气体法对广州市新建住宅不同封闭状态下的换气次数进行测量并研究不同的计算方法和测量时间对测量结果的影响。结果表明:1)与非线性回归法相比,差分法的计算结果高度一致,相对偏差基本保持在 5 % 以内,国标法的相对偏差较大,最大为 19.38%;2)测量时间的长短对换气次数的影响表现为换气次数在 0.5~1.3h-1 时,30 min 后的测量结果趋于稳定,当换气次数小于 0.2 h-1 时,达到稳定的时间需要 2 h 左右;3)在被测卧室全封闭的状态下,换气次数均小于 0.5 h-1;当被测卧室打开直径大小约为 6 cm 的空调孔洞或同时让窗户打开一条缝时,换气次数显著提升,最大可达到 1.28 h-1。 相似文献
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为研究不同换气次数对化学分析实验室气流分布和污染物排放效果的影响,通过测试平台对通风柜面风速进行实测,与数值模拟结果进行比较,验证模拟的可靠性.对典型化学分析室进行数值模拟,对比分析了5~16次/h换气次数下房间内气体分布特性,总结出不同换气次数对污染物排放效果的影响.结果表明在满足通风柜面风速要求的前提下,房间控制区污染物浓度值并非随换气次数的增大而单调递减.当换气次数为10~12次/h时,室内空气品质最佳. 相似文献
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本文基于CFD模拟,通过对具体工程的实验动物房气流组织的模拟分析,研究实验动物房内最佳的换气次数,并由此分析了实验动物房洁净空调风系统的节能潜力。研究结果表明,在方形散流器上送下回的气流组织方式下,该实验动物房的最佳换气次数12次/h,与原设计系统设计换气次数为18次/h相比,空调风系统的能耗可节省33.4%。 相似文献
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《建筑科学》2017,(2)
燃香颗粒物是室内主要污染之一,为了解其排放状况,首次在环境舱内对大陆7种燃香颗粒物的排放特征进行了表征。研究结果表明:1)燃香产生的主要是细颗粒物PM_(2.5),且PM_(2.5)在PM_(10)中的占比在97.2%以上;2)燃香颗粒物PM_(2.5)和PM_(10)排放速率分别为35.130~131.020 mg/h和36.908~140.270 mg/h,PM_(2.5)和PM_(10)的排放因子分别为6.950~34.600mg/g和7.311~37.040 mg/g;3)环保无烟卫生香和环保无烟正檀香的颗粒物排放因子低于细线香和柏香但高于红藏香,其环保标识基本合理;4)利用燃香颗粒物排放速率预测单室内PM_(2.5)的质量浓度显示出换气次数由1次/h增到3次/h和5次/h后,颗粒物PM_(2.5)的浓度明显降低,且衰减时间由4个多小时缩到不足1小时。以上表明一般自然通风房间燃香时细颗粒物浓度高且暴露时间长,不利人体健康。故在室内燃香时通过开窗通风或机械通风的方式加大换气次数来减少燃香污染。 相似文献
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A PV system enhanced the performance of roof solar collector 总被引:1,自引:0,他引:1
A simple PV ventilation system was used to enhance the performance of roof solar collector (RSC) for reducing heat gain and increasing the ventilation rate inside houses. The RSC is composed of CPAC Monier concrete tiles at the outer side, air gap and gypsum board at the house side. The PV system consists of one PV panel (27 Wp), a DC electrical fan (7.3 W) installed in the gap of RSC and a control unit.
Field testing results showed that the average temperature gradient between CPAC tiles, gypsum board and room was low, about 7°C, demonstrating a high heat gain reduction. The temperature of gypsum board was very close to the indoor temperature. The average PV powered air flow rate and the corresponding air change per unit RSC were about 100–250 m3/h and 3–8 ACH, respectively. Such rates are 2–4 times higher than those obtained with the natural ventilation induced by RSC. In addition, PV-powered RSC is an interesting option in the sense that it promotes solar energy and conserve energy. 相似文献
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High ventilation rate is shown to be effective for reducing cross-infection risk of airborne diseases in hospitals and isolation rooms. Natural ventilation can deliver much higher ventilation rate than mechanical ventilation in an energy-efficient manner. This paper reports a field measurement of naturally ventilated hospital wards in Hong Kong and presents a possibility of using natural ventilation for infection control in hospital wards. Our measurements showed that natural ventilation could achieve high ventilation rates especially when both the windows and the doors were open in a ward. The highest ventilation rate recorded in our study was 69.0 ACH. The airflow pattern and the airflow direction were found to be unstable in some measurements with large openings. Mechanical fans were installed in a ward window to create a negative pressure difference. Measurements showed that the negative pressure difference was negligible with large openings but the overall airflow was controlled in the expected direction. When all the openings were closed and the exhaust fans were turned on, a reasonable negative pressure was created although the air temperature was uncontrolled. 相似文献
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为了对南京地区进行夜问通风的可行性进行预测,选取南京地区某典型办公楼,利用建筑全能耗模拟软件EnergyPlus进行了模拟研究。在典型气象条件下,分别考虑了通风时间,换气次数等因素对室内温湿度及空气比焓的影响。将室内空气焓值的变化等效为空气源热泵空调耗电量,通过对比空调的耗电量与通风风机的耗电量,得出最佳的换气次数,并进行了节能效果分析。结果表明:通风时间选择在室外温度较低的时间段内较为合适。换气次数在不同的通风时间下对应不同的临界点,当换气次数小于临界点的换气次数时,等效空调耗电量大于风机耗电量,此时具有节能效果。当通风时间为6:00~6:30时,换气次数为1-2ac/h时,等效空调的耗电量与风机的耗电量差值的绝对值最大,半小时通风的最大节能达到3.6kWh。 相似文献
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某高大厂房的空调设计与运行 总被引:2,自引:0,他引:2
根据某高大厂房工作区全部空调的要求,设计时采用了大风机盘管加变风量新风系统,分层空调中部侧送风,下部回风;非空调区上部设风口,过渡季大量使用新风。 相似文献
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Installation of supply/exhaust ventilation systems is a possible remedial action against excessive concentration of radon. Installations in some 15 one-family houses in Sweden have been evaluated regarding effectiveness, costs and impact on energy demad. This remedial action is most suitable when exhalation from the structure itself is the major source of radon. The resulting decrease in concentration of radon can be estimated from dilution in the increased flow of air through the building. The exhalation from the building materials is constant and unaffected by ventilation rate. When the radon originates from the soil subjacent to the building the inflow of radon is a function of untightness and pressure difference between soil and indoor air. The result of retrofitting a ventilation system will then be the combined effect of dilution and a possible change in pressure difference. The defects in these buildings are normally remedied by more cost-effective action based on sealing the route of entry or depressurising/ventilating the subjacent soil. If a ventilation system is installed, it should preferentially be a balanced supply/exhaust system in order to give a minimal negative pressure indoors. 相似文献