溶液除湿空调系统中叉流再生装置热质交换性能分析

再生器是溶液除湿空调系统中的重要传热传质部件。搭建了叉流再生器性能测试的实验台,并建立了叉流再生器中传热传质过程的数学模型。以溴化锂溶液为除湿剂,采用总换热量、全热效率描述再生器的热质交换总体效果,采用再生量、再生效率描述传质效果,实验测试了溶液和空气的进口参数对再生器性能的影响,并与逆流再生器的实验结果进行了比较。以实验得到的量纲一传质系数作为数学模型的输入条件,数值计算结果与73组实验数据吻合很好,全热效率和再生效率的偏差均集中在±15%以内。     

溶液除湿空调系列文章溶液式空调及其应用

分析了目前空调系统面临的主要问题，提出了基于溶液除湿空气处理方式的解决方案。介绍了溶液除湿空气处理方式的原理和系统构成方式，从改善室内空气质量、改进空调末端装置方式、节省能源、改善城市能源结构等方面讨论了这一方式的优点和特点。分析表明，基于溶液除湿空气处理方式的湿度独立控制空调系统可有效消除空气的霉菌、粉尘，可以根据人员数量调节新风量，并通过独立的吸收或提供显热的末端装置调节温度，实现室内温湿度的分别控制。溶液除湿空气处理方式还可有效地对排风进行全热回收，并在过渡季利用干燥或低温的新风，从而降低空气处理能耗。由于冷水不承担除湿任务，因此只需要18—21℃冷水用于吸收除湿过程释放的热量和室内显热。这就有可能利用各种自然冷源或采用高GOP的冷水机组。溶液除湿方式还可实现高密度的能量蓄存，从而协调各种能源供应中的负荷匹配。     

无霜式溶液除湿温湿度分控空调系统性能研究

提出了一种新的无霜空气源热泵驱动的溶液除湿温湿度分控空调系统,通过MATLAB建立了系统数学模型,对系统冬夏季工况系统性能进行了研究.夏季工况下,除湿器进口溶液浓度、 再生流量比例、 冷凝热比分别为0.25、0.2、0.5时,系统COP可达最佳,COP值为2.34～5.23.与同类系统相比,其COPR值均大于1,系统性...     

利用冷凝热回收的除湿液再生装置研究

以某示范楼为研究对象,提出了一种节能的空调系统方案,该方案涉及一种新型除湿液再生装置,其技术特征是将冷凝热回收用于溶液再生.定义了温湿度独立控制溶液除湿空调系统总的冷源设备热力系数,并根据此系数判断空调系统是否节能.理论分析表明,利用高温冷水机组冷凝器产生的热量用于除湿液再生,其系统总的冷源设备热力系数可达到6.27,比传统空调系统的冷源设备热力系数提高了45.5%,节能潜力可观.     

液体除湿空调系统国内外研究进展

对液体除湿空调系统、除湿剂、除湿系统中热质交换数学模型的国内外研究进展进行了阐述.     

空调工程中填料的研究现状

对空调领域中填料在蒸发冷却和溶液除湿等方面的国内外研究现状进行了阐述，并分析了填料内热质交换的影响因素，提出了提高空调系统中填料性能的建议。     

溶液除湿方式对室内空气品质影响的初步研究

在溶液除湿空调空气处理过程中，因溶液与空气直接接触，可能对室内空气品质产生负面影响，但同时也可以去除空气中的有害物质。以溴化锂溶液为例，进行了室内空气溴、锂离子的测定，溴化锂溶液对甲醛的吸收实验，除湿溶液对细菌和病毒生长的影响实验，并初步探讨了气液交换模块的除尘作用。     

溶液除湿空调系统在工业厂房应用的能耗分析

通过对深圳某工业厂房分别选用常规冷凝除湿空调系统和溶液除湿空调系统进行系统设计和理论计算分析,比较了两类空调系统的能耗及COP。在夏季室外设计工况下,常规冷凝除湿空调系统的COP为2.94,溶液除湿空调系统的COP为5.42。室外空气含湿量越小,对提高溶液除湿系统的性能越有利。溶液除湿空调系统在节能方面具有较大的优势。     

基于高压雾化的溶液除湿性能实验研究

采用高压雾化将除湿液雾化成细小颗粒,可增大溶液除湿的接触面积,从而提高除湿效率。基于高压雾化的原理,搭建高压雾化溶液除湿系统实验台,研究空气量、溶液流量、空气状态对雾化除湿性能的影响。结果表明:高压雾化溶液除湿系统的除湿量随空气量、进口空气含湿量以及溶液流量的增加而增加;在进口空气温度为29.5℃,含湿量为21.44 g/kg,液气比为0.19的情况下,实验系统单位溶液除湿量可达15.78 g/kg;实验过程中,单位溶液的平均除湿量为10.39 g/kg;在相同除湿量下,雾化溶液除湿的单位溶液除湿量比传统填料式除湿器高2倍以上;拟合出除湿量的经验公式,可知实验值与测量值吻合得较好。     

液体除湿空调系统的研究分析

在液体除湿过程中,空气与溶液之间发生的传热、传质作用是相互影响的,空气中的水蒸气分压力与溶液表面上的饱和蒸气压力差为两者之间的传质作用提供动力。由于除湿溶液喷淋在填料表面的同时,能够对流经填料之间的空气起到除尘过滤的作用,从而降低了空气中颗粒物的浓度,提高了进入室内空气的品质。但因空气和除湿溶液在填料表面直接接触进行传热传质,容易发生除湿空气夹带液体进入室内,因此对除湿空调系统做了湿式除尘以及泡沫夹带进行相关理论分析。     

Comparative study on internally heated and adiabatic regenerators in liquid desiccant air conditioning system

Liquid desiccant regeneration has important effect on performance of a liquid desiccant air conditioning system. Compared with conventional packed regenerator, internally heated regenerator is proposed to achieve better regeneration performance. This study emphasized on both regeneration rate and regeneration thermal efficiency to evaluate the performance of both regenerators. A validated heat and mass transfer model was used to analyse and compare the performance of internally heated and adiabatic regenerators. The results indicated that internally heated regenerator not only could increase the regenerate rate, but also could exhibit higher energy utilization efficiency. Different from adiabatic regenerator, internally heated regenerator can provide comparable regeneration efficiency and regeneration rate at low desiccant flow rate, so it should be a good alternative to avoid carryover of desiccant droplets. Higher air flow rate would result in a deduction of regeneration thermal efficiency although achieving higher regeneration rate. Suitable flow rate of the air should be considered carefully in liquid desiccant regeneration. The internally regenerator could have considerable prospect in liquid desiccant air conditioning application.     

溶液全热回收装置与热泵系统结合的新风机组

提出了一种以溶液为媒介的全热回收装置和热泵系统相结合的新风处理机。安装于某医院的新风机性能测试结果表明：测试条件下，新风机夏季性能系数为6．3～7．3，冬季性能系数为4．7～5．0。新风机中吸湿溶液能去除空气中多种污染物，可避免新风和室内排风之间的交叉污染。     

溶液除湿过程热质交换规律分析

除湿器和再生器是溶液除湿系统的重要传热传质部件。建立了一个测试叉流除湿、再生模块性能的实验台,以溴化锂溶液为除湿剂,用除湿量、除湿效率和体积传质系数描述除湿效果,实验测试了溶液和被处理空气的进口参数对除湿器性能的影响。由实验数据得到的准则关联式,可供叉流除湿器设计参考使用。     

叉流除湿器中溶液与空气热质交换模型

建立了简化数学模型 ,空气出口温度和含湿量、溶液出口温度和质量分数的数值计算结果与实验结果的偏差在± 1 0 %以内 ,全热效率和除湿效率的偏差在± 2 0 %以内。通过分析除湿器内部温度场和浓度场得出 :在叉流除湿器中 ,不能忽略空气温湿度沿溶液流动方向和溶液温度沿空气流动方向的变化 ;传质驱动势要采用积分平均湿差的方法计算 ,而不能简单地采用对数平均湿差来表示     

利用蒸发式冷凝器再生除湿溶液时传质系数的实验研究

建立了溶液再生式蒸发冷凝器实验台,利用冷凝热再生氯化锂除湿溶液,对影响空气与除湿溶液之间传质系数的主要因素进行了实验测试.在大量实验数据基础上,分析了除湿溶液质量流速及空气迎面风速对空气与液膜之间传质系数的影响,并回归得到了传质系数的经验公式,为利用低品位热源再生除湿溶液提供理论依据.     

Simulation and experimental analysis of a fresh air-handling unit with liquid desiccant sensible and latent heat recovery

This article introduces a liquid desiccant fresh air processor. Its driving force is low-grade heat (heat obtained from 65 – 75°C hot water). Inside the processor, the air is dehumidified by the evaporative cooling energy of the indoor exhaust air. A four-stage structure is used to increase the efficiency of the combined sensible and latent heat recovery from the exhaust air. A mathematical model of the fresh air processor was set up using Simulink®. A liquid desiccant fresh air processor was constructed and tested for outside air conditions of 29.1 – 33.6°C, 13.7 – 16.7g/kg humidity ratio, and supply air conditions of 23.6 – 24.2°C, 7.4 – 8.6g/kg humidity ratio. The average measured COP _f was 1.6 (cold production divided by latent heat removed) for the range of conditions tested. The corresponding average COP _sys of the system including the regenerator was 1.3 (cold production divided by heat input). The detailed operating parameters of each part of the test unit were also measured. The test data was compared with the simulated performance. The characteristic coefficients (such as the volumetric mass transfer coefficient of the air-water evaporative cooling module, etc.) in the mathematical model were modified to calibrate the model output to the measured data. The calibrated simulation model was used to investigate the control strategy of the fresh air processor. The flow rate of the strong solution into the unit and the number of operation stages may be controlled separately or together to meet different indoor air requirements at different outdoor conditions. The hot water driven liquid desiccant air conditioning system was compared with a typical vapor compression system with an average COP of 4.5; the pump and fan power of the proposed system was 40% of the combined chiller, pump, and fan consumption. We achieved savings of over 30% of the power consumption compared with the traditional system under the designed outdoor air conditions.     

采用吸湿剂处理湿空气的流程优化分析

分析了吸湿剂与空气直接接触的热湿传递过程,得到了溶液与空气热湿传递过程中传热、传湿阻力表达式,比较了溶液-空气不同进口状态的传热、传湿不匹配系数.在溶液进口状态等浓度线上进行的热湿传递过程传热、传湿不匹配系数最小,而等焓线上发生的过程的传热、传湿不匹配系数较大.在构建溶液与空气的热湿处理流程中,应尽可能使除湿与再生过程贴近溶液等浓度线进行.固体吸湿剂与溶液之间的性质差异使得固体吸湿剂与空气间的热湿传递过程一般沿着等焓线发生.     

Experimental investigation of solar heating and humidification system based on desiccant bed heat exchanger

In this article, an experimental investigation has been made on a solar heating and humidification system. In this system, an evacuated tube solar water heater is connected to the desiccant bed heat exchanger (DBHE) by connecting pipes. The evacuated tube solar water heater supplies required heat to the DBHE for the regeneration of desiccant material. Various types of solid and composite desiccant materials have been used in the DBHE to investigate their effect on the system performance. It has been found that the system obtained its best performance with silica gel with average humidification rate of 0.63?kg/h. The maximum temperature difference of process air has been found as 16°C at the flow rate of 295.2?kg/h.     

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.