太阳能溶液除湿空调系统在工厂的应用分析

介绍了基于太阳能集热、溶液除湿和水蒸发冷却技术结合的太阳能溶液除湿空调的原理；提出了一种太阳能溶液除湿空调系统，并对该系统在工厂的应用进行了分析；认为太阳能溶液除湿空调有着独特的优点：环保、节能、可方便的储存能量，可应用于传统空调所不能胜任的工厂和车间，有着较大的经济效益和社会意义。     

太阳能溶液除湿再生器的模拟和试验研究

针对溶液除湿空调系统再生过程的传热传质特性,通过试验研究再生器内部不同截面中心位置的温度分布,有无填料对再生器的影响。在对溶液除湿空调中溶液再生机制研究的基础上,建立再生器的数学模型。研究结果表明模拟数据与试验数据较好地吻合,能够为太阳能溶液除湿再生器的优化提供理论依据。     

液体除湿空调系统溶液再生性能的理论研究与实验分析

建立了液体除湿空调系统再生塔数学模型,对再生塔内溶液再生性能进行理论研究和模拟计算;并利用液体除湿空调系统实验台,进行再生实验,与理论计算进行对比分析,研究影响溶液再生性能的主要因素,以提高再生性能。     

一个可利用低品位热能的双级除湿冷却式空调系统

本文建立了一个可利用低品位热能的双级除湿冷却式空调系统及其数学模型,并用该模型模拟香港一办公楼作为新风系统的除湿冷却式空调系统。计算机模拟结果显示：双级系统所需的再生温度仅为５９．０℃,较单级系统低２４．２℃,这使得低品位热能的利用成为可能;双级除湿冷却式空调系统可提供湿度足够低的送风,以承担全部湿负荷,故该系统可以很好地与冷幅射天花板系统配合使用,从而实现显热与潜热的分别处理,提高温湿度的控制精度;而且由于机械制冷仅仅被用于消除显热,所以可以提高制冷系统的蒸发温度从而提高制冷系统的性能系数。     

叉流除湿器热质传递性能实验研究

在太阳能溶液除湿蒸发冷却空调系统实验台上,以LiCl溶液为除湿剂,用空气进出口含湿量差和除湿效率作为除湿过程的性能评价指标,来研究叉流除湿器的除湿性能。通过实验数据分析了溶液、空气进口参数对除湿性能的影响,并利用实验数据建立适用于LiCl溶液的叉流除湿器的除湿效率和传质系数的实验关联式,发现与实验结果的吻合程度很好,误差在15%以内,能够利用这些关联式来准确的计算叉流除湿器的除湿性能,可供叉流除湿器设计参考使用。最后将实验结果与相关文献进行比较,结果表明:不同的除湿剂对叉流除湿器的除湿性能的影响基本相同。     

间接蒸发冷却技术在北京地区数据中心的应用分析

结合北京地区的气候特点,分析了间接蒸发冷却空调在数据中心不同送/回风温度、冷却效率时的切换温度及全年运行时长;通过建立计算模型,计算了对应不同空调送/回风温度、间接冷却效率时的能耗情况,并以某数据中心为例,计算了采用间接蒸发冷却空调和传统空调的初投资、运行费用等;根据计算结果分析,同等冷却效率下,提高空调送回风温度可显著降低全年空调电耗;采用间接蒸发冷却空调比传统空调节省电耗44%。     

液体除湿空调再生传质特性的实验研究

分析了液体除湿空调再生过程热质交换的耦合特性,并提出了提高再生过程热质交换性能的措施,在此基础建立了液体除湿空调系统,其中再生器采用逆流式填料塔,在填料塔设置中间加热器,利用排风进行再生。使用氯化锂作为除湿剂,实验分析了影响再生传质性能的主要因素以及提高再生性能措施的有效性,结果表明：再生溶液温度、流量以及空气流量对再生传质量的影响比较显著,为了保证一定的再生量,溶液温度一般不低于60℃;采用室内排风再生和再热器再热均增强了再生过程传质势,提高了再生量。     

回收排风潜能的新型液体除湿空调的应用研究

研究了一种利用排风潜能的全新风液体除湿空调装置,描述了系统原理及流程;该系统通过回收排风潜能,降低系统中直接蒸发喷淋水的温度,使除湿处理后的空调送风得到降温加湿,达到空调房间所要求的送风温度。同时,空调排风的利用,降低了再生空气介质的温度和含湿量,提高了再生溶液的浓度;针对上海夏季气候特点,对系统的节能性能做了分析,并指出该系统在节能和低品位能源利用上的应用意义。     

热泵型溶液调湿系统的补水量计算

对无预冷型和预冷型溶液调湿空调系统的溶液浓度平衡进行理论分析,并给出系统补水量的数学模型。计算结果表明:对于无预冷溶液调湿空调系统,系统补水量与系统性能系数基本无关,随除湿器干球温差的增大或再生器干球温差的减小而增大;对于预冷型溶液调湿空调系统,系统补水量随系统性能系数的增大或再生器干球温差的减小而增大。对不同补水方式进行比较,结果表明,溶液调湿空调系统应优先采用脉冲式补水方法。     

二次回风系统与一次回风系统在除湿过程的节能比较

传统的冷却除湿通常采用带一次回风的空调箱系统,其存在大量的冷热抵消,采用二次回风空调箱系统能够较好的避免冷热抵消。通过对一医疗器械厂房采用的一二次回风系统在除湿过程中所消耗的电量进行计算比较,得出了二次回风在一个除湿周期的节电量。同时计算二次回风系统的动态投资回收期以及指出了该系统的适用范围。     

Use of compound desiccant to develop high performance desiccant cooling system

The paper is aimed to develop a high performance rotary solid desiccant cooling system using a novel compound desiccant wheel (DW). The unique feature of the desiccant wheel is that it can work well under a lower regeneration temperature and have a higher dehumidification capacity due to the contribution of the new compound desiccant materials. Experimental results indicate that the novel desiccant wheel under practical operation can remove more moisture from the process air by about 20–40% over the desiccant wheel employing regular silica gel. A mathematical model that is used to predict the system performance has been validated with the test results. By integrating the desiccant wheel with evaporative cooling, heat recovery and heating for regeneration sections, a solid desiccant cooling system can be formed. Simulation results show that because of the use of the new compound desiccant, the desiccant cooling system can work under much lower regeneration temperature and have a relative high COP, thus low grade thermal energy resources, such as solar energy, waste heat, etc., can be efficiently utilized to drive such a cooling cycle.     

Analysis of an air cycle refrigerator driving air conditioning system integrated desiccant system

This study presents theoretical investigation on the performance of air cycle refrigerator driving air conditioning system integrated desiccant system. Total system performance is evaluated and the system feasibility is examined. The system has such characteristics that (1) safe material of air and water are used as a refrigerant, (2) waste heat from air cycle refrigerator performs the regeneration of desiccant material for energy saving. It has been clarifying that (1) controlling the evaporative cooling process in air washer, the system can operate for a wide range of cooling loads, (2) the total coefficient of performance on air conditioning system is better than the conventional vapor compression system with reheating coil, and (3) the system performance highly depends on the ratio of the amount of outdoor intake air to the supply air.     

浅谈术语“气体吸湿剂＂

“固体吸湿剂”、“液体吸湿剂”常作为吸湿剂中的两大类型被提及。固体吸湿剂利用吸附原理,对湿空气进行除湿;液体吸湿剂利用吸收原理,使空气达到除湿的效果。而压缩空气作为一种极为干燥的空气,我们称之为“气体吸湿剂”,此空气通过和湿空气混合,实现对湿空气稀释除湿的目的。同时经过压缩空气气体吸湿剂除湿后的空气可以与蒸发冷却技术相结合应用于空调中,大大提高蒸发冷却降温的效率。另外,在我国西北等干燥地区大气中存在着一种经过大自然除湿后的天然干燥空气一千空气,我们可充分利用这种气体吸湿剂,直接送入建筑物内消除室内的湿负荷,大大降低人工制冷除湿的能耗,同时充分利用“干空气能”,达到尽量采用蒸发冷却天然冷源降温的效果,从而实现建筑低能耗的目的。“气体吸湿剂”是一种新的吸湿剂概念,为此,本文对术语“气体吸湿剂”进行了初步的探讨。     

The potential of solar energy use in desiccant cooling cycles

The use of heat produced by solar thermal collectors is an interesting option for thermal driven air conditioning processes. A thermal driven cooling technique which fits well to non-tracking solar collectors is the desiccant cooling technique. Recently several projects have been carried out which focus on the connection of desiccant cooling systems with solar thermal energy for regeneration of the sorbents. This communication deals with three main topics: (1) experiences achieved in a realized system which is coupled to a solar collector are discussed, (2) a new concept is presented, in which a solar air collector is integrated into the desiccant cooling cycle as the only heat source and (3) a comparative study is presented which compares system performance for different system configurations and different climatic situations.     

Hybrid liquid desiccant air-conditioning systems: A conceptual study with respect to energy saving potentials

In conventional air-conditioning systems with vapour compression cycles the dehumidification is realised by cooling the air below the dew point of the supply air. One possibility to avoid cooling the air below the dew point and thus to reduce the electric energy demand of air-conditioning systems is hybrid liquid desiccant air-conditioning systems (HLDACS) which use an open absorption cycle for dehumidification of the air. This conceptual study examines four different HLDACS with respect to their electric energy demand and shows energy saving potentials compared to a conventional air-conditioning system for three different climatic design conditions. All considered systems consist of an open absorption system in combination with either a vapour compression system (VCS) or an indirect evaporative cooling system. The results show that electric energy savings of 30–60% depending on the HLDACS and climates are possible.     

Performance analysis of a solar cooling plant based on a liquid desiccant evaporative cooler

Summer air conditioning represents a growing market in buildings worldwide, with a significant growth rate observed in European commercial and residential buildings. Available heat driven cooling technologies can be used in combination with solar thermal collectors to reduce the load caused by air conditioning on the electric utilities and to reduce the environmental impact. This work reports a performance analysis of an open cycle solar cooling plant. The plant, installed in Northern Italy, is based on a liquid desiccant evaporative cooler coupled with a solar field. Experimental tests run during summer show average primary energy ratio and primary energy saving index of about 1.6 and 30%, respectively. Though this performance is satisfactorily, the regeneration unit always operated near the lower bound of the nominal temperature range. Therefore, optimization of the solar system design could lead to higher performance.     

Evaluation of heat and mass transfer coefficients in a gauze-type structured packing air dehumidifier operating with liquid desiccant

In this paper, high performance packing, namely, structured packing that has good heat and mass transfer characteristics, is proposed for dehumidification of air using liquid desiccants and for regeneration of liquid desiccants. In order to design a structured packing tower for liquid desiccant — air contacting operations, heat and mass transfer coefficients for each phase are required. This paper is concerned with the interface transfer of heat and mass when air is brought into contact with the liquid desiccant solution. A theoretical study of evaluating heat and mass coefficients in an air-desiccant contact system employing three liquid desiccants, namely calcium chloride, lithium chloride, and a mixture of 50% calcium chloride and 50% lithium chloride (called cost effective liquid desiccant, CELD) is investigated. Moreover, air phase transfer coefficients are correlated with flow rates of air and liquid and the temperature of air, whereas liquid phase coefficients are correlated with rates of air and liquid flow, and the temperature and concentration of the liquid. The findings for the three liquid desiccants are compared and discussed.     

太阳能驱动的转轮除湿蒸发冷却空调系统理论研究

为了响应国家节能政策的要求,降低建筑的能耗需求以及避免传统空调系统CFCs对臭氧层的破坏,本文试图提出一种太阳能驱动的转轮除温蒸发冷却空调系统,并以办公室为例,从理论上分析了该系统的性能,为该系统的下一步优化设计及实验提供理论参考。     

Effect of desiccant isotherm on the performance of desiccant wheel

Numerical simulation has been conducted for the desiccant wheel, which is the crucial component of a desiccant cooling system. As the key operating/design parameters, the rotation speed and the area ratio of regeneration to dehumidification have been examined for a range of regeneration temperature from 50 °C to 150 °C. Optimization of these parameters is conducted based on the wheel performance evaluated by means of Moisture Removal Capacity (MRC). Simulations are focused on the effect of desiccant isotherm on the optimal conditions of these operating/design parameters. Also the effects of the outdoor air temperature and humidity on the optimum design parameters are examined.     

Experimental performance analysis and modelling of liquid desiccant cooling systems for air conditioning in residential buildings

The paper presents a new desiccant cooling cycle to be integrated in residential mechanical ventilation systems. The process shifts the air treatment completely to the return air side, so that the supply air can be cooled by a heat exchanger. Purely sensible cooling is an essential requirement for residential buildings with no maintenance guarantee for supply air humidifiers. As the cooling power is generated on the exhaust air side, the dehumidification process needs to be highly efficient to provide low supply air temperatures. Solid rotating desiccant wheels have been experimentally compared with liquid sorption systems using contact matrix absorbers and cross flow heat exchangers. The best dehumidification performance at no temperature increase was obtained in an evaporatively cooled heat exchanger with sprayed lithium chloride solution. Up to 7 g kg⁻¹ dehumidification could be reached in an isothermal process, although the surface wetting of the first prototype was low. The process then provides inlet air conditions below 20 °C for the summer design conditions of 32 °C, 40% relative humidity. With air volume flow rates of 200 m³ h⁻¹ the system can provide 886 W of cooling power.A theoretical model for both the contact absorber and the cross flow system has been developed and validated against experimental data for a wide range of operating conditions. A simulation study identified the optimisation potential of the system, if for example the surface wetting of the liquid desiccant can be improved.