溶液除湿系统再生性能的研究进展

溶液除湿系统不存在温室效应,对环境友好,实现了热负荷和湿负荷的独立处理,提高了人们生活和工作环境的空气品质。但在溶液吸湿的过程中,溶液浓度会不断降低,溶液表面与空气之间的水蒸气分压力差会逐渐减小,溶液失去除湿能力,需要对溶液进行再生才能循环使用。再生器是盐溶液提浓循环使用的重要场所。本文简要介绍了溶液除湿系统再生性能的研究现状以及一些不同于传统再生的方法。     

溶液除湿系统除湿性能实验研究

基于正交试验设计方法,对入口溶液质量分数、入口溶液温度、入口液气比、入口空气含湿量、入口空气温度这5个因素对出口空气含湿量的影响进行了实验研究.结果表明,除湿量受前4个因素的影响较显著,受入口空气温度影响较小;入口液气比较小时,除湿量随入口液气比的增大而增大,但当入口液气比大于1.5后,除湿量几乎不随入口液气比的增大而变化;对单位除湿量的影响程度由大到小为:入口空气含湿量、入口溶液质量分数、入口溶液温度、入口液气比、入口空气温度.     

非常温溶液除湿自主再生空调系统性能分析

本文提出一种新型的将溶液除湿与热泵相结合的温湿度独立处理空调系统,该系统使用低温、低浓度的除湿溶液,在任何工况下冷凝热都能满足溶液再生的需求。建立了整个系统的数学模型,研究系统自身参数变化(溶液温度、浓度)和环境参数变化(空气温度、湿度)对系统性能的影响;并对系统应对高温、高湿度环境的调整方法进行了分析。结果表明,在夏季典型工况下,除湿溶液的理想温度为17-19℃、相应的质量浓度为25.39%-26.88%;系统具有较高的能效,并且能够在高温潮湿地区发挥其节能潜力。     

溶液除湿空调系统蓄能性能分析

介绍了溶液除湿蒸发冷却空调系统的蓄能原理,分析了蓄能密度的影响因素。与冰蓄冷、水蓄冷和气体水合物蓄冷等常规蓄冷方式的比较结果表明,溶液除湿空调系统在蓄能方面有明显的优势,其蓄能密度远大于常规蓄冷方式。该系统可以利用太阳能作为再生能源,白天蓄存浓溶液用于夜间制冷,节能效果显著。     

再生面积与除湿面积比率对除湿转轮性能的影响

建立了转轮除湿机单通道内传热传质一维瞬态数学模型,利用麦考马克时间推进方法进行离散求解,对不同再生温度和转速下除湿机稳态运行时出口平均含湿量随再生面积与除湿面积比率的变化做出了预测和分析,并得到了不同工况下最优比率。     

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。     

内热再生式除湿器除湿再生性能数值模拟

针对建筑环境内小空间微环境的特殊除湿需求,提出一种内热再生式除湿器,建立了其吸附再生过程的数学模型,并开发了基于有限差分方法的数值求解程序对其进行求解。根据求解结果给出了除湿器尺寸的推荐值,得到了除湿器在基本工作过程中的动态特性,并分析了几种常见因素对除湿器性能的影响。结果表明,处理气流量较小时,该除湿器在连续运行且不采用内冷措施的情况下仍能对高湿气体长时间保持较高的除湿效率,再生过程所需时间远小于有效除湿时间。     

溶液除湿系统中除湿塔的设计

对溶液除湿系统中除湿塔填料层直径和高度的设计进行了理论分析,并通过具体参数说明了设计计算的方法和步骤,以积累溶液除湿系统中除湿塔的设计经验,完善除湿塔的设计。     

广州地区太阳能溶液除湿再生温度的研究

本文以广州为例,根据气象站太阳辐射统计数据,理论计算了该地区太阳能热水器集热量。再生热能全部利用太阳能的条件下,根据广州地区室外气候特点,求解再生量随再生温度的变化关系。计算条件下,5、10月份广州地区再生量最大时对应的再生温度分别为59℃和72℃。     

Performance analysis of liquid desiccant based air-conditioning system under variable fresh air ratios

In conventional air-conditioning system, fresh air volume is always restricted to save energy, which sacrifices indoor air quality (IAQ) to some extent. However, removing the latent load of air by liquid desiccant rather than by cooling is an alternative way of reducing energy consumption. Therefore, IAQ can be improved by increasing the volume of fresh air introduced into an air-conditioning system. In this paper, a liquid desiccant based air-conditioning system is studied, with the system performance under various fresh air ratios analyzed using simulation tests. In addition, the proposed system and a conventional system are compared. In the proposed system, with the increase in fresh air ratio, the heating load for solution regeneration rises, the dehumidification efficiency increases and the regeneration efficiency drops. The coefficient of performance (COP) of the liquid desiccant based system decreases sharply when the fresh air ratio exceeds 60%. The results also show that the proposed system can save power notably. The maximum power saving ratio is 58.9% when the fresh air ratio is 20%; however, the ratio drops when the fresh air ratio increases. These findings will be beneficial in the selection of fresh air ventilation strategies for liquid desiccant based air-conditioning systems.     

Exergy performance and thermodynamic properties of the ideal liquid desiccant dehumidification system

In this paper, an ideal liquid desiccant dehumidification system is presented as the idealization of practical liquid desiccant dehumidification systems, along with an exergy analysis that considers the effects of various parameters like dehumidification temperature, water vapor pressure and temperature of surrounding environment on the system performance. Exergy formulations are developed and validated for the ideal system. These results show that the ideal system is strongly influenced by these impact factors, with respect to operating condition and exergy efficiency, and should be used with caution when comparing with condensation-based dehumidification systems.     

液体除湿填料塔液体夹带和压降问题研究

分析了填料塔液体夹带量和压降与气流速度和溶液流量的关系,通过实验研究得出了液体夹带量随风机频率和溶液流量的变化关系,提出了解决液体夹带问题的方法。     

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。     

Control strategies for a liquid desiccant air-conditioning system

Liquid desiccants are energy efficient in air dehumidification. A significant amount of research has been conducted on liquid desiccant systems, but little attention has been paid to the control issues surrounding such system. In this study, a novel dedicated outdoor air-conditioning system that adopts liquid desiccant dehumidification is proposed. A simulator of the proposed system is built on the TRNSYS platform. Control methods for the supply air dehumidification and solution regeneration processes are presented, and their effectiveness is evaluated. Two control strategies are developed for the proposed liquid desiccant system based on the evaluation results. The control performances of these two strategies are compared under different operation conditions using simulation tests.     

一种新型液体除湿空调的应用

分析了常规液体除湿空调的不足,开发了一种新型液体除湿空调装置,介绍了其系统原理及流程。在上海高温高湿的气候条件下的实际应用表明该系统在节能和低品位能源利用方面有重要意义。     

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.     

Performance of a solar-regenerated liquid desiccant ventilation pre-conditioning system

A solar-regenerated liquid desiccant ventilation pre-conditioning system has been proposed for use in hot and humid climates. The system aims to dehumidify the ventilation air which is the major source of latent load. A heat exchanger is used to cool the dehumidified air instead of typical evaporative cooling to maintain the dryness of the air. The use of solar energy at the regeneration process and cooling water from a cooling tower makes the system more passive. The simulation procedure for the proposed system has been presented. By inputting the climatic data and the physical parameters of all equipments, the operating parameters at each equipment and the performance parameters of the system can be evaluated. The simulation procedure is demonstrated by showing the daily profiles of the operating and performance parameters on a typical day as well as investigating the influence of the selected operating parameters on the system performance. The results suggest that the most influential parameters are solar radiation, ventilation rate, and desiccant solution concentration. The balance between the water removed at the dehumidifier and that evaporated at the regenerator needs to be considered to maintain uniform performance during continuous operation.