空调节能技术和措施的辨识(2)——地板送风系统设计中的困惑(上)

通过文献阅读、实验研究、工程调查,分析了现行的地板送风系统负荷计算和送风量确定过程中存在的主要问题。实验室实验和工程实践结果表明:在国内采用地板送风系统的一般办公室中,很难形成空气分层,分层与否影响空调送风量,而送风量又决定了空气是否分层;地板送风系统的负荷和送风量计算与顶送风常规空调系统并无本质区别,考虑到人体舒适感,地板送风系统的送风温度更高,送风量一般明显大于顶送风常规空调系统。空调负荷和送风量计算是地板送风系统设计中的关键,其正确与否,不但影响系统的经济性,而且还会影响系统的可行性,有必要进行深入的研究、分析和探讨。     

小型空气净化通风系统中风量分配器性能优化

为了实现自控系统根据房间人数调控风量,采用风量分配器分配风量。为优化风量分配器的均匀可调性,本文模拟研究了导流片高度,角度对风量分配的影响,并对其进行了分析。结果表明,当导流片高度为120 mm时,调节导流片角度,风量分配效果最优。     

DDC变风量控制器在定风量洁净空调工程中的应用

1机械式定风量阀常规的定风量阀,是一种机械式自力控制装置,适用于需要恒定风量的通风空调系统中。机械式定风量阀的风量控制不需要外加动力。     

变风量的魅力——DDC变风量控制器在定风量洁净空调工程中的应用

1机械式定风量阀 常规的定风量阀，是一种机械式自力控制装置，适用于需要恒定风量的通风空调系统中。机械式定风量阀的风量控制不需要外加动力。     

高压系统变风量空调器的自动控制

一、变风量系统的特点变风量系统的主要功能是,送入某区的风量随该区的冷负荷变化。变风量系统所具有的主要特点是: 1.风管系统中输送变化着的风量。 2.各变风量空调器中进行由恒温器控制的风量调节。 3.送入各房间的风量是变化的。 4.单纯的变风量系统与一个补偿热负荷     

超高层建筑前室的加压系统设计分析

通过对超高层建筑前室加压系统设计进行分析,建议前室加压系统送风量应取连续三层最大送风量,并探讨了避难层前室的加压系统的设计。     

VAV空调系统总风量控制方法探讨

本文针对VAV空调系统提出了一种基于末端风机转速的总风量优化控制方法,利用变频风机取代VAV BOX风阀作为风量调节机构,以末端设备的实际送风量之和作为VAV空气处理机组风机变频控制依据。本文利用Matlab/Simulink软件分别建立了该控制方法与传统风量控制方法下系统室内温度调节仿真模型,对比分析了两种控制方法下系统的调节性能,结果表明该控制方法下系统可获得更好的调节性能,室内温度及房间送风量的调节更加稳定,超调量小,调节时间短,末端送风压力得到有效保证,室内具有良好的舒适性。     

南京市档案馆通风除尘系统改建探讨

南京市档案馆原通风除湿系统未考虑除尘功能 ,经多年使用 ,发现系统中 (特别是送回风管道内 )积聚较多的灰尘 ,不利于档案、资料和光盘等的保存。我们经过对系统的分析 ,找出了灰尘量增多的原因 ,在原有的基础上 ,提出了改进方案 ,并对系统实施施工安装、调试和测试分析 ,结果表明 ,系统综合性能大为提高 ,并满足其技术性能要求。1　原通风除湿系统 (见图 1 )图 1　改造前系统示意图为保持改造后的系统送风量低于原设计风量的比例不大于 1 5% ,首先对原通风除湿系统进行风量测试 ,实测得每层总送风量为 50 0 0ｍ3/ｈ ,每个送风口风量为 62 0…     

影响空调系统调试中的主要问题及解决方法

空调系统调试的目的是保证室内温度达到设计条件，满足使用要求。在调试中常见的问题有：风量不均，送风温度不稳，噪音偏大等，但其中主要问题是风量不均，从而导致其它问题的发生；。所以系统调整送风量是解决问题关键。本文主要介绍空调系统调试中如何调整风量不均的方法。     

风量分配器的试验研究

本文介绍了通过试验研究利用旋流在风管内送风以均匀分配风量的新技术,及在等截面圆风管上风口分布离散的均匀送风系统中能自动平衡各风口风量的风量分配器的研制。本试验研究在有效风管长度50D,风口间距4D时,观测在起始端设与不设匀流器等多因素变化情况,与不装风量分配器的工况进行对比试验后,成功地开发出新的均匀送风系统和设备——风量分配器。     

洁净室空气热湿处理能耗分析

分析了一次回风加再热系统、二次回风系统的空气处理过程,并以山西大学光电楼的一间100级实验室为例,对这两个方案的空气热湿处理过程进行了能耗分析,结果表明采用二次回风系统的方案最节能。     

Study on biological contaminant control strategies under different ventilation models in hospital operating room

Transmission of airborne bacteria is the main factor causing surgical site infection (SSI). Previous researches have provided evidence of relationships between cleanness of room air and incidence of SSI, but little work has been done to verify the numerical simulation results of particle dispersion. This paper focuses on the airborne transmission of bacteria in two operating rooms during two surgeries: a surgical stitching of fractured mandible and a joint replacement surgery. Field measurement was carried out in two newly built ISO class 5 (OR.A) and class 6 (OR.B) operating rooms. Bacteria collecting agar dishes were put in different places of the two operating rooms to get the deposited bacteria number during the operation. Then numerical simulation was carried out to calculate the particle trajectories using the Euler–Lagrange approach. Simulation results were compared with field measured data, and acceptable level of consistency was found. Then we changed the supply air velocity and supply vent area in the OR.B numerical model under same room air change rate, to compare bacteria colony deposition onto the “critical area”, which consisted of three connected surfaces around the surgical site on patient body. Result showed that improving air flow pattern can reduce particle deposition on critical surface, but its effect is less evident by increasing the air change rate in a certain amount, and we found that bacteria colony deposition would increase (mainly on upper surface), if air velocity increases beyond a certain velocity.     

Air water flows in building drainage systems

This paper investigates the mechanisms of two-phase flows that occur in commercial and industrial roof drainage systems. Both traditional gravity-fed and siphonic roof drainage systems are examined.

Air entrainment plays a fundamental role in the performance of siphonic roof drainage systems. In particular, air entrainment has a significant effect on:

• maximum system flowrate capacity;

• pipe friction losses;

• operational system pressures;

• operational gutter water depths; and

• ability of the system to prime.

However, experimental results presented here demonstrate that the reduction in system capacity is not directly proportional to the increase in air content. One possible explanation for this is that water and air will be affected differently by sub-atmospheric pressures. The effect air entrainment has on roof drainage performance is investigated. The ways in which air is introduced into the system are identified and the effects of different air/water ratios are quantified. Finally methods for reducing air entrainment are described.     

Assessing dynamic efficiency of air curtain in reducing whole building annual energy usage

The efficiency of air curtain in reducing infiltration and associated energy usage is currently evaluated statically by using an efficiency factor, η _air, based on single steady/static condition, which is often not the case for actual buildings under variable weather conditions and door usages. Based on a new method to consider these dynamic effects on air curtains, this study uses a dynamic efficiency factor η _B in terms of whole building site end-use energy to assess the efficiency of air curtains when compared to single doors (i.e. without air curtains) and vestibule doors. Annual energy simulations were conducted for two reference building models considering their specific door usage schedules in 16 climate zone locations in the North America. The variations of the proposed efficiency factor for different climate zones illustrated the dynamic impacts of weather, building, unit fan energy and door usage frequency on air curtain efficiency. A sensitivity study was also conducted for the operation temperature conditions of air curtain and showed that η _B also considers these operational conditions. It was thus concluded that using whole building site end-use energy to calculate the efficiency factor, ηB, can provide more realistic estimates of the performance of air curtains operations in buildings than the existing static efficiency factor.     

Demand controlled ventilation: A case study for existing Swedish multifamily buildings

The aim of the work accounted for in this paper has been to investigate a demand controlled ventilation (DCV) system for a typical Swedish multifamily building with exhaust ventilation. Another aim has been to apply and evaluate the IDA Indoor Climate and Energy (ICE) simulation software in this application. The work has been related to a renovation project of a large number of apartments with exhaust ventilation systems recently carried out by a Swedish municipal housing association.A typical apartment, chosen among 1000 existing apartments, has been modelled using IDA Climate and Energy simulation software. Four exhaust ventilation system concepts have been evaluated:

• 1.reference system with constant air volume flow;
• 2.demand controlled ventilation system: carbon dioxide control, variable air flow;
• 3.demand controlled ventilation system: humidity control, variable air flow;
• 4.demand controlled ventilation system: occupancy control, variable air flow.

The simulations show that it would be possible to achieve energy savings using occupancy and/or humidity controlled ventilation to reduce the average ventilation flow rate while keeping an acceptable indoor climate. Based on the simulation results a demand controlled ventilation system is developed and implemented in occupied apartments in order to investigate the performance.A measurement based validation of the simulation program indicates that it can be applied reliably.     

玉柴机器集团柔性生产线车间远程射流送风空调系统

72台远程射流送风空调机组布置在车间两侧,机组的出风口为球型喷口;新风经室 外2台组合式空调机组处理后,通过风管由双喷口型新风口送入车间。经济分析和实测结果 表明,与常规空调系统相比,年运行费用可降低58%左右;车间温度分布均匀,工作区风速在设 计范围内,空调设备噪声较小。     

Performance evaluation of air quality models for predicting PM10 and PM2.5 concentrations at urban traffic intersection during winter period

There are several models that can be used to evaluate roadside air quality. The comparison of the operational performance of different models pertinent to local conditions is desirable so that the model that performs best can be identified. Three air quality models, namely the 'modified General Finite Line Source Model' (M-GFLSM) of particulates, the 'California Line Source' (CALINE3) model, and the 'California Line Source for Queuing & Hot Spot Calculations' (CAL3QHC) model have been identified for evaluating the air quality at one of the busiest traffic intersections in the city of Guwahati. These models have been evaluated statistically with the vehicle-derived airborne particulate mass emissions in two sizes, i.e. PM10 and PM2.5, the prevailing meteorology and the temporal distribution of the measured daily average PM10 and PM2.5 concentrations in wintertime. The study has shown that the CAL3QHC model would make better predictions compared to other models for varied meteorology and traffic conditions. The detailed study reveals that the agreements between the measured and the modeled PM10 and PM2.5 concentrations have been reasonably good for CALINE3 and CAL3QHC models. Further detailed analysis shows that the CAL3QHC model performed well compared to the CALINE3. The monthly performance measures have also led to the similar results. These two models have also outperformed for a class of wind speed velocities except for low winds (<1 m s(-1)), for which, the M-GFLSM model has shown the tendency of better performance for PM10. Nevertheless, the CAL3QHC model has outperformed for both the particulate sizes and for all the wind classes, which therefore can be optional for air quality assessment at urban traffic intersections.     

Influence of capillary water on compressive strength of marls

Tests of compressive strength carried out on calcareous marl samples showed very different results in the four following cases:

1. the test was made in air on a dry sample,
2. in air on a sample saturated with water by capillary rise,
3. in air on a fully water-saturated sample,
4. in water on a fully water-saturated sample.

These results are interesting on a theretical point of view, and also on a practical point of view for works to be carried out under the ground-water table.     

Research on a personalized targeted air supply device based on body movement capture

Unlike general ventilation, personalized ventilation can improve thermal comfort and conserve energy based on individual differences. It can also provide every individual the ability to control fresh air exposure and ensure good indoor air quality. However, determining how to improve air supply efficiency while avoiding a draft sensation is still a difficult question. This paper introduces a body movement-based personalized targeted air supply device. Two indices, size target value and velocity target value , are introduced to evaluate the degree to which the created flow field reaches the desired level. Additionally, the air supply effect of the device is compared with that of other devices. This research shows that the personalized targeted air supply device can successfully deliver air to the target area and improve air supply accessibility in the target area. The multinozzle coupling air supply mode produces a flow field air velocity of approximately 0.3 m/s, thus effectively avoiding a draft sensation. Compared with that of other personalized nozzles, the energy consumption is reduced significantly, by 88.2%, while the air supply accessibility can be increased by 48% with equivalent energy consumption.