电子厂房空调系统自然供冷率及节能分析

电子厂房空调系统需要全年供冷,在冬季,利用冷却塔自然供冷可以节约冷水机组的运行能耗,其节能潜力较为可观。本文针对上海地区某电子厂房空调系统,分析了冷却塔间接供冷方式下供水温度、冷却塔及板式换热器效率对自然供冷率的影响。通过自然供冷率的对比,分析系统的节能潜力。研究结果表明,在12月到3月四个月内采用冷却塔自然供冷,可以...     

华润大厦空调系统

大厦空调水系统为四管制变水量系统,冬季采用冷却塔供冷。空调风系统为内外分区的全空气变风量系统,变风量系统采用单风道定静压点控制,风机变频,标准层采用环形风道。末端装置采用压力无关的节流型,内区常年供冷;外区末端加设热水再热盘管。新风集中处理,为保证足够的新风量,各层采用定新风量、变新回风比的控制方式。     

冷却塔自然供冷空调系统的结构与控制分析

对常年需供冷水的空调系统,冬季及过渡季节利用冷却塔自然供冷的方式具有一定的节能潜力。本文以上海地区某电子厂房空调系统为研究对象,研究分析串/并联型式下冷却塔间接供冷的节能潜力,提出包括供冷模式转换控制,冷水机组启停控制,冷却塔启停控制和冷却塔出水温度控制的系统运行控制策略。通过搭建的冷却塔自然供冷系统动态仿真器,对串/并联型式的系统自然供冷率,系统控制效果以及系统全年能耗情况进行了仿真分析。仿真结果表明,串联式的系统节能潜力优于并联式,两者的运行能耗差距随着供水温度设定的提高而减小。     

方圆大厦空调设计

该大厦集办公、商业、娱乐、餐饮等功能于一体，内区范围大，主体办公用房及商场采用分区两管制系统。介绍了大厦的空调方案和运行调试情况，根据该空调系统运行的实际效果，认为分区两管制空调系统是一种经济实用的空调方式，总结了设计的成功与不足之处。     

变风量系统分区设计对某超高层办公建筑空调能耗的影响

以北京地区某超高层办公建筑为例,采用DeST软件模拟计算了不同朝向建筑分区的全年逐时冷热负荷。比较了4种不同变风量空调系统形式的全年供冷、供热量及运行费用。通过对比分析可得,应根据建筑分区负荷特点采用内外区分设空调及新风系统的方案,但是设置热回收新风机组的节能性不佳。     

神华大厦空调冷热源及系统设计

介绍了空调水系统、风系统及自控系统的设计特点.该工程采用冰蓄冷系统供冷、燃气锅炉供热,冬季内区采用冷却塔供冷;办公楼风机盘管水系统分别采用了两管制和四管制变水量系统;根据建筑使用功能及用途分别对应设置了全空气空调系统、风机盘管加新风空调系统及分体多联式空调系统.     

东营蓝海酒店空调冷热源及系统设计

本文介绍酒店空调冷热源及系统的设计特点和控制方法。采用地源热泵为空调冷热源,热回收型热泵机组供冷的同时可以供应生活热水。冬季内区利用水源回水进行换冷供冷。对土壤换热器的结构及设计形式进行了详细阐述。本文对酒店空调水系统、风系统、集中热回收系统和消声减振措施进行阐述。     

合肥万达城内区免费制冷的经济性分析

针对合肥地区的万达实际项目,比较免费制冷和常规空调系统两种方式的内区供冷系统初投资,并根据当地的能源价格,比较两种方式的全年运行费用,得出了该项目免费制冷的回收期。结果表明,采用免费制冷的方式进行内区供冷虽然造成初投资略有增加,但使能耗降低较多,具有较好的经济性。     

不同除湿方式户式辐射空调系统能耗研究

模拟比较了冷水式除湿、制冷剂直膨式除湿、双冷源除湿3种除湿方式下户式辐射空调系统的夏季供冷能耗.结果显示:3种除湿方式下,空调房间温度均能满足要求,采用制冷剂直膨式除湿时室内温度略低,双冷源除湿时室内温度略高;采用制冷剂直膨式除湿的户式辐射空调系统能耗最低,冷水式除湿能耗最高,直膨式除湿的能耗较冷水式除湿约低15％,较...     

空调系统的分区多工况运行调节方法

介绍了空调系统送风状态点的确定和空调工况分区原则,详细分析了三种空调工况分区运行调节方法的特点,认为在全年运行的工艺性空调系统的控制设计中,采用五工况分区调节方式是最佳的选择。     

Ventilation by displacement in a three-dimensional room— A numerical study

Displacement flow systems are becoming popular, especially in Scandinavia, for comfort ventilation. In these systems air is supplied near the floor at low velocity; the temperature of the supply air is a few degrees below that of the air in the room. The supply air is heated by persons and/or machinery in the room. Turbulent plumes are formed above these heat sources. Apart from the plumes, the flow in the room is divided into two zones: a lower zone (the occupied zone) to which clean cool air continuously is supplied, and an upper zone (above the occupied zone) where contaminated warm air is recirculating.

In the present study, the flow in displacement flow systems (a water box model) has been calculated using finite difference methods; the results have been compared with experimental data, and the agreement is reasonably good.     

空调内区余热问题解决方法探讨

建筑物内区余热已成为空调设计中不容忽视的问题。提出了内区分路设置冷冻机、内区分路设置板式换热器利用冷却塔供冷、利用新风机组送冷风以及利用设双风机的全空气系统解决内区余热问题的几种方法。     

Ventilation efficiencies of desk-mounted task/ambient conditioning systems

In laboratory experiments, we investigated two task/ambient conditioning systems with air supplied from desk-mounted air outlets to efficiently ventilate the breathing zone of heated manikins seated at desks. In most experiments, the task conditioning systems provided outside air while a conventional ventilation system provided additional space cooling but no outside air. Air change effectiveness (i.e., exhaust air age divided by age of air at the manikin's face) was measured with a tracer gas step-up procedure. Other tracer gases simulated the release of pollutants from nearby occupants and from the floor covering, and the associated pollutant removal efficiencies (i.e., exhaust air concentrations divided by concentrations at manikin's face) were calculated. High values of air change effectiveness (approximately 1.3 to 1.9) and high values of pollutant removal efficiency (approximately 1.2 to 1.6) were measured when these task conditioning systems supplied 100% outdoor air at a flow rate of 7 to 9 L s-1 per occupant. Air change effectiveness was reasonably well correlated with the pollutant removal efficiency. Overall, the experimental data suggest that these task/ambient conditioning systems can be used to improve ventilation and air quality or to save energy while maintaining a typical level of IAQ at the breathing zone.     

Similarity of coupled heat and mass transfer between air–water and air–liquid desiccant direct-contact systems

Packed-bed heat and mass transfer devices are widely used in air-conditioning systems, such as cooling tower, evaporative cooler of air–water direct-contact devices, dehumidifier and regenerator of air–liquid desiccant direct-contact devices. Similarities of heat and mass transfer characteristics between air–water and air–liquid desiccant devices are considered and investigated in this paper. Same reachable handling region of outlet air can be obtained for both air–water and air–liquid desiccant devices, which is among three boundary lines, isenthalpic line of inlet air, iso-relative humidity line of inlet fluid (water or desiccant), and the connecting line of inlet statuses of air and fluid. Inlet conditions of air and fluid affect heat and mass transfer characteristics to some extent, so that a zonal method is proposed only according to the relative statuses of inlet air to inlet fluid. Four zones, dehumidification zones A, D and regeneration zones B, C, are divided for air-desiccant direct-contact devices. The first three zones A, B and C are divided for air–water direct-contact devices, with the same zonal properties as those of air-desiccant devices. In order to obtain better humidification performance, fluid should be heated (in zone C) rather than air (in zone B). And fluid should be cooled (in zone A) rather than air (in zone D) to obtain better dehumidification performance. Counter-flow pattern should be applied for best mass transfer performance in the same conditions within the recommended zone A or C, while parallel-flow pattern is the best in zone B or D.     

Experimental investigation of dehumidification process in cooling coil by utilizing air-to-air heat exchanger in humid climate of Iran

Energy recovery systems can be used in HVAC to reduce energy consumption by recovering wasted energy from the exhausted air to pre-cool inlet fresh air. In this paper, experimental study of utilizing cooling coil (CC) and cooling coil combined with heat exchanger (CCHE) has been developed. Considering the different climate zones in Iran, the experimental study has been done for the areas with high humidity content. In each case, the effects of air-to-air heat exchanger (HE) on the sensible and latent cooling load are investigated. The analysis gives the applicability of HE in Iran for various operational conditions to obtain air with lower moisture content. In CCHE systems more latent load quota is allocated in cooling coils and lower air humidity ratio can be obtained. Also in the cities with higher dew point depression (difference between dry-bulb and dew point temperature) more humidity reduction is achieved and the difference between latent load quotas of CCHE system is higher than CC system.     

Experimental investigation of two-stage indirect/direct evaporative cooling system in various climatic conditions

Cooling performance of two-stage indirect/direct evaporative cooling system is experimentally investigated in the various simulated climatic conditions. For this purpose, a two-stage evaporative cooling experimental setup consisting of an indirect evaporative cooling stage (IEC) followed by a direct evaporative cooling stage (DEC) was designed, constructed and tested. Due to the wide variety of climatic conditions in Iran, two air simulators were provided to simulate outdoor design condition of different cities in primary and secondary air streams. Results show that under various outdoor conditions, the effectiveness of IEC stage varies over a range of 55–61% and the effectiveness of IEC/DEC unit varies over a range of 108–111%. Aspects of achieving comfort conditions and power saving have been investigated with related excess water consumption. Considering the evaporative comfort zone, this system can provide comfort condition in a vast region in Iran where direct evaporative alone is not able to provide summer comfort condition. More than 60% power saving could be obtained by this system in comparison with mechanical vapor compression systems with just 55% increase in water consumption with respect to direct evaporative cooling systems. This system can fill the gap between direct evaporative cooling systems and mechanical vapor compression systems as an energy efficient and environmentally clean alternate.     

Influence of the floor-based obstructions on contaminant removal efficiency and effectiveness

Dimensioning of dilution ventilation is often made using the perfect mixing approximation, assuming uniform contaminant concentration throughout the room space. However, the contaminant removal efficiency and effectiveness of air conditioning system should be accounted for during design. The effectiveness is in this context used as a measure of the contaminant distribution uniformity within the occupied zone. Influence of an occupied zone obstruction level, air distribution method, air change rate, cooling load and contaminant source non-uniformity on the contaminant removal efficiency and occupied zone contaminant concentration uniformity were studied in scale model. The room air distribution method results in contaminant concentration non-uniformity inside the occupied zone. A method was developed to take this into account during the design of air distribution system. Contaminant supply non-uniformity was found to have great influence on the concentration non-uniformity with two tested air distribution methods.     

关键区温度重设定的自适应按需新风控制

针对多区域变风量空调系统,提出一种关键区温度重设定的自适应按需新风控制策略,以最少的能耗满足各区的室内空气质量要求。该策略实时检测各区人员负荷,识别关键区,充分考虑关键区的新风需求,在进行新风设定时充分考虑循环空气中没有使用完的新风。关键区的温度重设定可以加大输送到关键区的送风量从而加大关键区的新风量,新风比减小,从而达到节能目的。利用多区域变风量空调系统的动态仿真平台对该控制策略进行了测试,对其动态控制性能、能耗特性及空气质量特性进行了评估,同时将该控制策略与其他按需新风控制策略进行了比较。     

利用新风系统消除内区余热的设计探讨

将风机盘管加新风系统的设计做出部分调整,使其冬季或过渡季在室外空气为冷源,对建筑物的内区或其它需供冷区域进行供冷,达到节约能源的目的。     

西直门综合交通枢纽工程空调通风系统设计

介绍了西直门综合交通枢纽工程空调通风系统的优化设计。采用了多项空调节能措施:大冷量离心冷水机组搭配变频小冷量机组,二次泵变频变流量空调水系统,四管制风机盘管冬季用冷却塔换冷供冷设计,商业外区风机盘管、内区全空气空调系统,送风机、排风机变频控制,过渡季、冬季利用室外新风通风降温的焓值控制设计。