地铁专用间接蒸发冷却器布水方式优化

为了解决常规间接蒸发冷却器由于表面水膜均匀性、完整性差而导致换热效率低的问题,提出了两侧旋转布水间接蒸发冷却器,进行了3种布置方式下的换热性能实验,运用正交实验对影响换热器性能的因素进行研究,研究表明:开孔正对气流方向时换热器换热性能最佳,且旋转布水装置存在最佳转速76r/min,喷水量、空气流速、冷却水流量、冷却水进口温度的增加使换热器的换热量增大,喷水温度、空气温度的升高使换热器的换热量减少,其中冷却水进口温度的改变对换热性能的影响最为显著,温度由35℃上升到39℃时,换热量提高37.62%,单位面积换热量为1.14kW,该换热器可安装于地下车站排风坑道内,可有效地解决地铁站冷却塔安装位置难题。     

空调用蒸发式冷凝器能耗实验研究

当室外气温较高时,风冷热泵系统冷凝器存在换热效果下降的问题,而蒸发式冷凝器可以改善此问题,蒸发式冷凝器因此逐步得到广泛重视。为研究采用蒸发式冷凝器制冷系统的能耗情况,通过正交实验的方法,对比研究了蒸发式冷凝器与风冷式冷凝器在相同工况下压缩机能耗情况,并对影响其性能的因素进行了分析。研究表明,各因素对压缩机耗功量的影响能力依次为:冷凝器进口空气温度、速度及冷凝器喷水量。压缩机耗功量随进口空气温度的升高、进风空气速度降低而增大,随喷水量增加存在先减小后保持不变的现象。     

间接蒸发冷却用气-水雾化喷嘴特性实验研究

为了提高间接蒸发冷却器换热效率,提出了将气－水雾化喷嘴应用于间接蒸发冷却器改进换热器表面水膜的均匀性,实验研究了扇形两相(气－水)喷嘴在不同空气压力和水压下的特性,测出了不同压力时喷嘴雾化角和气水质量流量值,得出了其变化规律,确定出了最佳的喷雾气水压力比和雾化角等参数。     

两种间接蒸发冷却器的三维数值模拟和分析

基于计算流体力学（CFD）方法，建立了板式和管式间接蒸发冷却器的数学物理模型，通过三维数值模拟得到了换热器一、二次空气通道的速度场、温度场和浓度场的分布。对比并分析了两种类型的蒸发冷却器性能，结果表明板式间接蒸发冷却器的换热面积大，换热效率和火用效率均高于管式。通过性能分析可为进一步进行换热器的优化设计提供理论基础。     

微通道换热器空气侧换热性能影响实验研究

针对微通道蒸发器的换热性能,在结露条件下,分析了冷冻水进口温度、空气进口温度、空气流速大小等参数对空气出口温度、换热器换热系数、空气侧压降等实验结果的影响程度,研究发现:提高冷冻水进口温度,空气侧换热系数和压降有不同程度降低,而空气出口温度有所升高。     

烟气与水冷凝换热影响因素实验研究

搭建了基于吸收式热泵的直接接触式烟气余热回收实验系统,通过实验研究了水气比、喷嘴形式、喷嘴排数、过量空气系数、喷淋高度、喷水温度、排烟温度对直接接触式换热器性能的影响。测试了凝结水量和冷凝水的pH值,以及换热器烟气侧阻力。结果表明,影响烟气-水换热效率的主要因素是水气比、喷淋高度和喷水雾化粒径,排烟温度、喷水温度和过量空气系数对换热效率也有一定影响。整个余热回收系统的实验测试结果达到了设计要求。     

结构参数对管式蒸发冷却器冷却性能的影响

管式蒸发冷却器是蒸发冷却技术应用中的一个重要设备。本文建立了管式蒸发冷却器的数学模型，采用MATLAB编程，分析了换热器的长度、宽度及管间距的变化对其冷却性能的影响规律，主要从管式蒸发冷却器的传热系数和传质系数角度分析，并综合考虑对风机和水泵能耗的影响。研究结果表明：换热的长度和宽度在合适的范围内取值，管间距是盘管外径的2倍时，管式蒸发冷却器的冷却性能较好。所分析的结果可以为管式蒸发冷却器的设计提供参考依据。     

露点蒸发冷却技术的发展及其在数据机房冷却中的应用

露点蒸发冷却可以将空气温度降至进口空气湿球温度以下,理想状态下可达到进口空气的露点温度。露点蒸发冷却器冷却性能受湿通道内表面润湿材料、冷却器结构及运行参数影响。概述了露点蒸发冷却器在湿通道材料选择、冷却器结构及运行参数优化方面的研究现状及研究进展,以及其在数据机房冷却中的不同应用形式。     

管式间接蒸发冷却器换热效率的推理和分析

结合管式间接蒸发冷却器数学模型分析,得出间接蒸发冷却器一次空气的换热效率εp、一次空气的对流换热系数αp、二次空气与水膜的热湿交换效率εs和二次空气的对流传质系数σs,并经过推理和分析得出一种适用于工程实践的间接蒸发冷却器效率E的计算公式,为管式间接蒸发冷却器的理论研究和实际应用计算提供依据。     

微通道换热器换热性能的数值模拟及试验

采用数值模拟、试验方法,对微通道换热器的换热性能进行探究(主要考核空气出口温度、换热量、空气压力降、空气侧表面传热系数等)。将空气作为微通道换热器外部高温换热介质,将冷水作为微通道内部低温换热介质,不考虑冷水分配的不均匀性,对比分析在不同迎面风速、冷水进口温度条件下微通道换热器的换热性能。空气进口温度设定为35℃,相对湿度设定为60%(模拟时不考虑空气相对湿度对微通道换热器结露的影响),微通道换热器的迎面风速变化范围为1. 00～1. 75 m/s。冷水流量设定为1 m~3/h,冷水进口温度变化范围为5～8℃。空气出口温度、换热量、空气压力降、空气侧表面传热系数随迎面风速、冷水进口温度的变化趋势模拟与试验基本一致,由于试验条件下微通道换热器翅片易出现结露,使得试验条件下的空气压力降大于模拟结果。冷水进口温度为5℃时,空气出口温度、换热量、空气压力降、空气侧表面传热系数均随迎面风速的增大而增大。迎面风速为1. 5 m/s时,空气出口温度随冷水进口温度的增大而增大,换热量、空气压力降、空气侧表面传热系数均随冷水进口温度的增大而减小。     

On-site experimental testing of a novel dew point evaporative cooler

Technologies which utilise the advantages of evaporative cooling to reduce the temperature of air without the addition of moisture have existed for some time. These systems use a heat exchange media between the evaporation of water process and cooling of air. Research has been conducted on a number of systems utilising these technologies in various configurations and it has been demonstrated that temperatures of the incoming air can approach its dew point temperature. This is considerably lower than the wet bulb temperature which is the limit achieved with conventional direct evaporative cooling systems. Prototypes have been built to demonstrate the principles and temperatures achievable, but the technology has never been developed due to its high cost and complexity. These disadvantages have been addressed in a newly developed indirect evaporative cooler. The paper presents results obtained from testing a prototype cooler installed in both a commercial and residential application in a wide range of ambient conditions. The performance characteristic of the indirect evaporative cooler in regards to its outlet temperatures and electrical energy efficiency is presented.     

Numerical study of a M-cycle cross-flow heat exchanger for indirect evaporative cooling

In this paper, numerical analyses of the thermal performance of an indirect evaporative air cooler incorporating a M-cycle cross-flow heat exchanger has been carried out. The numerical model was established from solving the coupled governing equations for heat and mass transfer between the product and working air, using the finite-element method. The model was developed using the EES (Engineering Equation Solver) environment and validated by published experimental data. Correlation between the cooling (wet-bulb) effectiveness, system COP and a number of air flow/exchanger parameters was developed. It is found that lower channel air velocity, lower inlet air relative humidity, and higher working-to-product air ratio yielded higher cooling effectiveness. The recommended average air velocities in dry and wet channels should not be greater than 1.77 m/s and 0.7 m/s, respectively. The optimum flow ratio of working-to-product air for this cooler is 50%. The channel geometric sizes, i.e. channel length and height, also impose significant impact to system performance. Longer channel length and smaller channel height contribute to increase of the system cooling effectiveness but lead to reduced system COP. The recommend channel height is 4 mm and the dimensionless channel length, i.e., ratio of the channel length to height, should be in the range 100 to 300. Numerical study results indicated that this new type of M-cycle heat and mass exchanger can achieve 16.7% higher cooling effectiveness compared with the conventional cross-flow heat and mass exchanger for the indirect evaporative cooler. The model of this kind is new and not yet reported in literatures. The results of the study help with design and performance analyses of such a new type of indirect evaporative air cooler, and in further, help increasing market rating of the technology within building air conditioning sector, which is currently dominated by the conventional compression refrigeration technology.     

管式间接蒸发冷风机性能测试及分析

本文搭建了1个管式间接蒸发冷风机实验台,对其进行了性能测试与分析,研究了其冷却效果、压降变化规律及水气比和一二次空气风量比对冷却效率的影响.通过实验可知,当冷风机的入口干球温度和干湿球温差较大时,降温效果明显;间歇供水比持续供水能创造出更高的蒸发冷却效率;随着一次风量的增加,冷风机的压降呈上升趋势;随着水气比和一二次空...     

交通岗亭间接水蒸发开式空调系统

将间接式水蒸发空调系统用于交通岗亭中 ,分析了系统的热力参数 ,建立了系统的数学模型 ,分析一次气流进口相对湿度及换热器效率对系统加湿量的影响 ,并给出计算例子。     

间接蒸发冷却方案的比较研究

根据数值模拟计算结果,比较了间接蒸发冷却器(IEC)和回热式间接蒸发冷却器(RIEC)的温度、换热效率火、用效比。结果表明RIEC的火用效比略低于IEC,但能得到更低的温度。这两种方案都有非常显著的节能潜力。     

间接蒸发冷水机组设计开发及性能分析

基于间接蒸发冷却技术设计了高温冷水机组,其驱动源为室外干空气而非电能,冷水机组的理论出水温度可无限接近进口空气的露点温度。建立了数学模型,并提出了系统的串联冷水流程,以更充分地利用室外干空气的能量。合作开发了第一台间接蒸发冷水机组,通过测试得到了实际机组的性能。最后分析了冷水机组作为湿度独立控制空调系统的高温冷源在中国西部及其他地区的应用。     

热管间接蒸发和吸湿冷却空调系统应用分析

间接蒸发和吸湿冷却在空调系统中得到广泛应用。热毛细泵循环式热管是一种能远距离传输能量且热阻低、传递温降小的高效热交换器。本文介绍了该新型热管用于间接蒸发和吸湿冷却空调系统热回收的工作原理，对该新型热管的原理及运行的毛细极限进行分析。对热管间接蒸发和吸湿冷却空调系统的性能进行模拟和分析。结果表明，热管间接蒸发与吸湿冷却空调系统是一种节能复合空调器系统。     

Thermodynamic analysis of steam-injected gas turbine cycle power plant with inlet air cooling

Steam-injected gas turbine cycle is the modified arrangement of simple gas turbine (GT) cycle, wherein part of steam generated in a heat recovery steam generator is injected into the combustion chamber to increase power output and the efficiency. This paper studies the effect of integration of inlet air cooling, steam injection (SI) and film cooling (FC) on the performance of GT cycle. Two different methods for cooling the inlet air, namely inlet fogging and evaporative cooling, are considered for analysis here. Results show that the inlet fogging is better than evaporative cooling to achieve the lowest temperature at the compressor inlet. Thermodynamic performance of simple GT cycle is also compared with SI in GT cycle. The present study shows that GT cycle with integration of inlet fogging, SI and FC is a better configuration for achieving higher performance.