冷冻水大温差末端——风机盘管机组串联方案

提高冷冻水供回水温差,不仅可以降低冷冻水输送能耗,还可以提高冷水机组能效。发挥上述优点需要合适的水侧大温差末端设备。风机盘管机组是目前集中式空调系统广泛采用的一种末端设备。本文根据现有生产企业产品提出常规大温差风机盘管机组与干式风机盘管机组串联运行的水侧大温差末端方案,对比分析串联机组与常规机组的性能参数,结果表明,串联机组可降低水流量60%左右,噪声、供冷量等指标可以满足集中式空调系统的要求。     

风机盘管机组与地板辐射联合系统供冷能力影响因素分析

针对风机盘管机组与地板辐射联合系统的供冷能力建立数学模型,通过模拟计算得到地板辐射盘管间距、地板材料及辐射盘管内供回水平均温度对地板温度的影响,进而得到风机盘管机组不同冷冻水供水温度、供回水温差条件下供冷量变化规律,为风机盘管机组与木地板辐射联合系统的设计应用提供依据。模拟结果显示,对于木地板表面,辐射盘管间距为200 mm时,风机盘管机组冷冻水供回水温差由5℃增大到10℃,其供冷量下降了32.29%;当风机盘管机组冷冻水供回水温差为7℃时,辐射盘管间距由100 mm增大到300 mm,导致供冷量下降了6.76%,而在150 mm的辐射盘管间距条件下,风机盘管机组冷冻水供水温度3℃时的供冷量相比供水温度8℃时的供冷量增大了约58.19%。     

热媒水温差对空气加热器及风机盘管性能影响的研究

提高中央空调水系统循环水温差,以减少循环水泵输送能耗,越来越受到业内人士的关注。为了能够更加清楚地了解循环水温差的调节对空调末端空气处理设备性能的影响,本文从理论分析展开,然后利用瞬时系统模拟程序TRNSYS建立了实验室空调系统仿真器,在对模拟结果进行实验验证的基础上,模拟分析变热媒水温差对末端设备换热量的影响。结果表明,供水温度一定,空气加热器及风机盘管换热性能随热媒水温差增大而下降,但是在一定范围内调节,增大热媒水温差,并且供水温度提到足够大的值时,空气加热器及风机盘管换热性能也会得到提高。最后指出选择合理热媒水温差与供水温度,要综合考虑空调系统水力稳定性、冷热源机组COP的大小、和送风温差的影响。     

与冰蓄冷相结合的大温差风机盘管系统性能研究

介绍了与冰蓄冷相结合的大温差风机盘管系统原理,并在冰蓄冷空调系统的不同运行工况下,对风机盘管的能效比和冷风比的理论计算值和实际运行值进行了比较,分析了冰蓄冷和大温差风机盘管相结合情况下的能效。     

温和地区采用大温差空调系统的技术经济分析

在温和地区的气候条件下和特定的使用功能要求下,分析比较了空调水系统采用大温差和常规温差对于风机盘管﹑新风和空气处理机组﹑冷水机组﹑冷冻冷却水泵﹑冷却塔﹑空调热水泵等设备运行工况的影响,认为对本项目最适宜的选择是空调冷水5∽12℃、热水60∽45℃,冷却水28∽36℃。     

干式风机盘管机组应用研究

针对干式风机盘管机组的使用特点,调研行业内关于干式风机盘管机组的研究与发展,结合多年的干式风机盘管产品开发及工程实际使用经验,找出抑制干式风机盘管机组广泛应用的制约因素——换热能力差。并提出一些换热能力优化解决方案:通过优化盘管的管径、翅片的结构,可以增加换热流体在有限空间内的扰流效果;设置合理的翅片间距、盘管排数,以增大换热面积;合理设置换热器的流型,以提高冷热流体间的平均传热温差;调整换热器的流路数,找到最佳的冷冻水管程,适当增加冷热流体的接触时间,进一步优化传热效果。结果表明,通过一系列优化方案的实施,干式风机盘管机组的换热能力整体提升约30%。     

离心式冷水机组大温差设计运行特性的实验研究

中央空调冷冻水系统大温差设计可以显著降低输配能耗,对系统节能具有重要意义.但随设计温差增大、冷冻水流速降低,蒸发器水侧传热系数逐渐减小,成为制约冷水机组能效的主要因素.本文基于蒸发器换热机理,理论分析了冷冻水大温差对蒸发器换热性能的影响,并通过离心式冷水机组串联运行的方案,实验对比了大温差工况下不同水路流程对整机性能的...     

水冷式冷水机组大温差运行特性试验

在冷冻水大温差、冷却水大温差、冷冻水和冷却水同时大温差3种条件下,对按照国家标准名义工况设计制作的水冷式冷水机组试验样机进行测试。结果表明,在保持制冷量不变(相当于空调冷负荷一定)情况下,冷冻水大温差对冷冻水进、出水温度影响明显,对机组性能系数、压缩机排气温度、机组冷凝压力影响不明显;冷却水大温差时,冷冻水进、出水温度略有升高、机组性能系数明显降低、压缩机排气温度和机组冷凝压力明显升高;冷冻水和冷却水均大温差时,对以上参数的影响为冷冻水和冷却水分别大温差影响的叠加。     

中温水空调系统风机盘管的性能研究

本文结合中温水全回风空调系统与常规全回风空调系统的对比实验,分析了FP85系列风机盘管处理室内回风至平衡状态点时室内温湿度参数的变化规律,并通过盘管仿真的研究方法,模拟分析了冷冻水供水温度和管排数对盘管换热性能的影响规律。实验结果表明,当冷冻水供水温度从7℃增至9℃时,3排盘管FP85处理潜热的能力出现突降,且不能保证室内湿度舒适。当冷冻水供水温度每升高1℃时,室内平衡状态点的相对湿度增加11. 03%～12. 05%。对于6排盘管FP85,当冷冻水供水温度为9～12℃时,室内平衡状态点的温湿度参数均可满足舒适性空调的设计要求。仿真结果表明,当室内回风干、湿球温度分别为27. 01℃和19. 51℃,且4、5、6排风机盘管FP85均可保证室内温湿度舒适时,冷冻水供水温度每升高1℃,4排盘管的换热量降低6. 13%,析湿系数降低0. 045。相比于5、6排盘管,4排盘管的传热系数较大,除湿能力较优,故4排FP85盘管更适用于中温水空调系统。该研究表明中温水空调系统极具发展潜力并为其系统设计提供了理论依据。     

用(火用)分析法确定风机盘管机组性能的评价指标

在分析已有风机盘管机组性能评价指标的基础上,利用热力学第二定律和(火用)分析的方法,提出了一种新的风机盘管机组性能的评价指标.该指标简单实用,可以较合理地评价风机盘管机组的性能.     

大温差空气处理机组表冷器换热能力优化设计及实验验证

冷冻水系统大温差设计对空调系统节能具有重要意义。配套使用空气处理机组也需采用大温差设计,达到节能效果,本文在空气处理机组换热机理的理论基础上,分析了冷冻水大温差对空气处理设备换热性能的影响。通过优化表冷器管形、回路等方法,采用焓差法实验对比了大温差工况下不同管形、不同回路、不同翅片片距等对表冷器性能的影响,在相同换热截面下,大温差空气处理机组较常规机组能耗降低约20%,并在此基础上,提出了大温差表冷器优选结构方案,采用高效内齿形换热管,4排高效换热管可与6排光管表冷器达到相同冷风比,且整机能耗低约5%,为大温差设计的应用和实践提供借鉴和参考。     

The impact of evaporator fouling and filtration on the performance of packaged air conditioners

The goal of the study presented in this paper was to evaluate the impact of different filter types on the performance of three typical packaged air conditioners under both clean and fouled conditions. In a companion paper, combinations of six different levels of filtration and four different coils were tested under clean and fouled conditions. From the tests, it was found that fouling has a relatively small impact on air-side effective heat transfer coefficient, but can have a large impact on coil pressure drop. Data from the experimental study were used in developing simulation models for the three packaged air conditioners. Simulations show that the equipment cooling capacity is reduced with fouling primarily because of a decrease in air flow due to the increased pressure drop. In most cases, EER (energy efficiency ratio) was reduced with fouling primarily due to increased fan power. However, the changes in EER were relatively small, in the range of 1–10%. Equipment having low efficiency filters had higher EER after fouling than equipment with high efficiency filters, because high efficiency filters result in significantly higher pressure drops than low efficiency filters. The impact of the evaporator side fan efficiency was found to be significant. The energy penalty associated with high efficiency filters was reduced greatly when fan efficiency increased. Although high efficiency filters cause higher energy penalties they provide considerably better air quality. The quantity of dust passing through the coil with an MERV14 filter was approximately 30 times less than the dust passing the coil with an MERV4 filter. This difference was doubled when the MERV14 filter was compared to a case with no filter in place.     

Two-dimensional normal zone propagation in BSCCO-2223 pancake coils

We present the results of an experimental and analytical study of two-dimensional normal zone propagation in pancake test coils, wound with silver-sheathed BSCCO-2223 tapes. Two test coils were studied in detail, one having three and the other eight layers. Each test coil was housed in an adiabatic environment whose temperature (20-70 K) was controlled and maintained by a two-stage G-M cryocooler and placed in a background field (0-6 T) generated by a Bitter magnet. With a test coil carrying a transport current (0-200 A), a local heat disturbance was applied by a heater attached to the outermost layer of the coil. The resulting electrical and thermal responses of the coil were recorded with voltage taps and thermometers attached to the coil. A normal zone propagation code was developed to accurately simulate the voltage and temperature responses of each coil for both quenching and recovering events. The code solves the nonlinear transient heat diffusion equation in two-dimensional cylindrical coordinates with a finite difference method. As an application of this code, a two-coil system, with each coil comprised of one double pancake wound with silver-sheathed BSCCO tape, was studied for its quench behaviour as one of the coils was driven normal locally. The simulation results indicate that the value of a shunt resistor connected across the terminals of each coil has a profound effect on the level of hot-spot temperature reached in the quench initiation spot.     

室外环境参数对空气源热泵翅片管蒸发器动态结霜特性的影响

对一台空气源热泵空调器在不同环境条件下室外换热器的动态结霜性能进行了实验研究,分析了进风温、湿度对热泵空调器结霜量及霜层厚度的影响。实验中考虑了结霜引起的热泵系统蒸发温度及风机流量的变化,采用显微照相法测量翅片表面霜层厚度,结霜量则通过测量蒸发器进出口含湿量的方法来获得。实验结果表明,室外换热器结霜量随时间线性增长,而翅片表面霜层厚度则分为初始段、匀速增长段和快速增长段三个阶段;在结霜循环的最后20％～30％的快速增长段内霜层生长速率大大加快,可达匀速生长段霜层生长速率的2．4,3．3倍。对于不同的工况,蒸发器均在进风温度0～3℃附近时结霜最为严重,且相对湿度对霜层厚度的影响要大于对结霜量的影响。     

Mechanical and radiographic properties of a shape memory polymer composite for intracranial aneurysm coils

An intracranial aneurysm can be a serious condition that can go undetected until the aneurysm ruptures, causing hemorrhaging within the subarachnoid space surrounding the brain. The typical treatment for large aneurysms is by embolization using platinum coils. However, in about 15% of the cases treated by platinum coils, the aneurysm eventually re-opens as a result of the bio-inertness of platinum. One solution to this is to develop suitable materials with increased bio-activity to use as coil implants. In this research, a shape memory polymer (SMP), Calomer™, produced by The Polymer Technology Group, Inc., was investigated as a candidate for aneurysm coils. The SMP was tested to determine its thermo-mechanical properties and the strength of the shape recovery force. Composite SMP specimens containing tantalum filler were produced and tested to determine the mechanical effect of adding this radio-opaque metal. Thermo-mechanical testing showed that the material exhibited a shape recovery force a few degrees above the glass transition temperature, T_g. The effects of the addition were small and included a decrease in T_g and recovery force. SMP coils deployed inside a simulated aneurysm model demonstrate that typical hemodynamic forces do not hinder the shape recovery process. The radio-opacity of the Ta-filled material was characterized with clinical fluoroscopy.     

烟支吸附装置流场分析与优化设计

目的 针对烟支传递与包装平稳性差的缺点,采用计算流体动力学（CFD）方法对烟支吸附通道内部流场进行三维数值分析。方法 研究关键部位流动特性,分析流速、压力分布及湍流耗散,提出结构改进方案。结果 流场压力和流速在烟支吸附口与风机连接位置分布不合理,拐角处湍流动能高,烟支吸附口至风机位置压力损失为5 268 Pa。风机管道存在逆压梯度,产生气流漩涡,压力损失值为14 000 Pa,高于工业需求。优化模型中,风机管道包含2个拐角时,压力损失降低了7 000 Pa,烟支吸附效果提升了350%。风机管道包含一个拐角时,压力损失降低了6 200 Pa,烟支吸附效果提升了390%,通道流场分布合理性得到改善。结论 基于仿真结果,优化风机与出风口管道连接方式,通过流场分析可为烟支吸附装置的优化设计提供一定技术支持。     

户用空气源热泵机组除霜方法的实验研究

试验对比一台户用整体式空气源热泵机组的3种除霜方案：旁通制冷膨胀阀、风机提前启动和热气旁通融霜。结果表明,用外径16 mm的铜管旁通制冷膨胀阀是比较适合测试样机的除霜方法,在-3℃/90%工况下除霜时间由205 s缩短至99 s;当除霜温度设定为0℃时,提前启动风机可以避免系统的高低压出现大幅度的波动;而热气旁通融霜会导致机组的制热能力下降,但有利于机组在低温工况下的运行稳定性。最后对试验需要改进的地方进行简要说明。     

发电机复合材料护环的强度刚度分析和铺层设计

本文考虑了横向剪切变形的影响,采用“退化”的三维等参单元,建立承受非均匀表面力、离心体积力和热应力联合作用的一般层合各向异性壳的有限元公式和程序,并用它对25MW发电机玻璃纲护环进行刚度、强度分析。提出铺层缠绕的优化设计方案。      

基于分布式温度采集技术的中央空调节能运行方案设计

针对楼宇中央空调系统运行温度智能控制存在的问题,提出了一种现场可编程门阵列FPGA控制的数字式温湿度传感器对各楼层、多点进行温度实时巡检,对温度、湿度进行定时采集,测量结果通过RS485总线传输至主机,分析计算后输出控制指令对风机盘管进行变频控制.对水系统的温度和流量参数进行采集,通过工控机对空调负荷与末端负荷进行匹配...