A new solar coupling regeneration method for liquid desiccant air-conditioning system

A new solar coupling regeneration system is proposed in order to improve the reliability of solar desiccant regeneration system.The new system makes comprehensively use of the solar energy and can also be appropriate for energy-storage in a night operation mode when the electric power supply is at its valley.Comparison of the performance of the new system,the solar thermal regeneration system and the solar electrodialysis regeneration system are made and the influential factors of the performance of the new system are investigated.The results reveal that the new system will be more energy efficient than the solar thermal regeneration system and the solar electrodialysis regeneration system.

The Experiment and Simulation of Solid Desiccant Dehumidification for Air-Conditioning System in a Tropical Humid Climate

The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different dehumidifiers such as desiccant column and desiccant wheel were investigated. The ANSYS and TRASYS software were used to predict the results of dehumidifiers and the desiccant cooling systems, respectively. The desiccant bed contained approximately 15 kg of silica-gel, with 3 mm average diameter. Results indicated that the pressure drop and the adsorption rate of desiccant column are usually higher than those of the desiccant wheel. The feasible and practical adsorption rate of desiccant wheel was 0.102 kgw/h at air flow rate 1.0 kg/min, regenerated air temperature of 55?C and at a wheel speed of 2.5 rpm. The humidity ratio of conditioning space and cooling load of split-type air conditioner was decreased to 0.002 kgw/kgda (14%) and 0.71 kWth (19.26%), respectively. Consequently, the thermal comfort was improved from 0.5 PMV (10.12% PPD) to 0.3 PMV (7.04% PPD).

Design of ionic liquids as liquid desiccant for an air conditioning system

Suitable control of the humidity can contribute to electric energy savings. However, the present dehumidification system has many weak points. The liquid desiccant air-conditioning system has recently gained growing interest from the stand point of reducing energy consumption during dehumidification. In order to find the appropriate ionic liquids(ILs) as a desiccant for the liquid desiccant air-conditioner system, we conducted a systematic evaluation of the humidification capability of 16 types of ILs. Among the tested ILs, tributyl(methyl)phosphonium dimethyl phosphate([P4441][DMPO_4]) exhibited the best dehumidification capacity and had a less corrosive effect on four types of metals as possible piping materials. It should be noted that this [P_(4441)][DMPO_4] has a very stable nature and produced no odor while conducting the experiment and storing for over 1 year at room temperature under ambient conditions. Furthermore, it was revealed that a 77%(w/w) aqueous solution of [P4441][DMPO_4] worked as an efficient desiccant liquid for the liquid desiccant air-conditioner system.

Economic Investigation on the Ultrasonic Atomization Dehumidifying System with Liquid Desiccant and Its Potential Best-Fit Application

The performance of liquid desiccant dehumidification systems can be improved substantially by applying the ultrasonic atomization technology.However,considering the currently-high expense and extra power for the ultrasonic atomizers,it’s unclear if the ultzasonic atomization dehumidifying system(UADS)possesses good economic performance over the conventional packed-bed(PBD)systems.This paper conducted a comparative study on the economic performance between the UADS and PBD.An economic analysis model integrated with the empirical formulae was established while an office building located in Guangzhou,China was employed as the study case.The results indicate the UADS may fit best for buildings with deep-dehumidification needs but smaller-scale areas.

Recent progress in liquid desiccant dehumidification and air-conditioning:A review

This paper presents a literature review on the recent research progress in liquid desiccant dehumidification and air conditioning systems.The physical features of various liquid desiccant materials and their dehumidification performances have been summarized.With the aim to improve the dehumidification characteristics,mixed sol-vents desiccants have become research hot topics recently.Various types of dehumidifiers and their integration with liquid desiccant dehumidification system have been reviewed.The combination of liquid desiccant dehumid-ification system with solar collector,vapour compression system,heat pump system,CHP system,etc.have been grouped and compared.It is shown that the majority of the recent research work for liquid desiccant dehumid-ification systems has concentrated on numerical simulations,a considerable amount of works are still required for the practical investigations of innovative material(mixed solvents)and hybrid systems.

Design of quaternary ammonium type-ionic liquids as desiccants for an air-conditioning system

The liquid desiccant air-conditioning system allows reducing energy consumption compared to the conventional compressor-type air conditioners.In order to develop desiccant materials for air conditioners,we have investigated the dehumidification capability of quaternary ammonium Ionic Liquids(ILs)and the equilibrium water vapor pressure of aqueous solutions of these ammonium salts.Among the seven tested types of ILs,2-hydroxyN,N,N-trimethylethan-1-aminium dimethylphosphate([Ch][DMPO4])displayed the best dehumidification capability and the lowest equilibrium water vapor pressure.Furthermore,the 80%aqueous solution of[Ch][DMPO4]exhibited a less corrosive effect on four types of metals,i.e.,steel(hot dip zinc-aluminum alloy plated steel),copper(C1100P),aluminum(A5052),and stainless steel(SUS:SUS304).It should be noted that this[Ch][DMPO4]is not only non-toxic but also exhibits a stable nature;the aqueous solution produced no odor after storing for over 1 year under ambient conditions.

太阳能-地热能复合利用的溶液除湿空调系统研究

针对传统空调系统采用温湿度联合处理的方式而导致的舒适性差、能源消耗大等问题,以南昌市某建筑为研究对象,利用TRNSYS仿真软件建立太阳能-地热能复合利用的溶液除湿空调系统数学模型,并分析集热器面积及埋管数量对系统性能的影响,在此基础上选取合适的参数对系统全年运行工况进行模拟。同时针对夏季室外新风含湿量波动较大的问题,提出对新风采取分流处理的解决方式。结果表明:在制冷工况下,室内平均温度为26.1℃,相对湿度在50%~65%之间;在供暖工况下,室内平均温度为19.2℃,相对湿度大部分处于40%~60%之间,能够很好地控制室内热湿环境。供暖和制冷季节能效比分别为6.2和4.5,全年性能系数为4.7,明显高于传统的空调系统。

开式吸收式热泵系统的研究及应用进展

闭式蒸气吸收式热泵系统以热能和少量泵功驱动代替蒸气压缩热泵系统的压缩机驱动,分别实现工质的流动和内能的增加,节省了高品位电能的压缩功。开式吸收式系统相比于闭式吸收式热泵(制冷)系统,以蒸气压差和温度差同时驱动的直接接触式传热传质代替闭式系统温差驱动的间接传热,实现系统与外界环境的热质交换。针对开式吸收式系统的研究目前主要为不同应用相关研究,在闭式吸收系统的基础上精简结构,优化性能。本文主要从工质对、构型、部件三个方面总结目前开式吸收式系统的研究进展。因开式吸收式系统常与环境发生物质交换,对其工质对的研究需要在蒸气压低、不易结晶等传统吸收式工质对需要的物性基础上,更强调腐蚀性低、环境友好等特性。广义的开式吸收式系统有D型、AD型、ADC型、EAD型、EADC型5种基本构型,本文总结了5种基本构型在直接蒸发冷却制冷、气体除湿加湿处理、热湿气体潜热回收、制冷制热、蒸馏提纯等不同应用领域的研究。与闭式吸收式系统相比,强化环境与系统的传热传质是开式吸收式系统的研究重点。对于直接接触式传热传质部件,填料塔仍然是绝热开式吸收器/发生器的主要形式,基于膜的非直接接触式吸收/发生换热器作为直接接触式换热器的替代部件,其传热传质系数相对于直接接触式换热器仍有待提高。

食品库房类建筑中溶液调湿空调碳减排潜力应用研究

空调系统能耗是食品库房类建筑能耗的重要构成,为推动食品库房类建筑的低碳化发展,通过现场测试与模拟分析相结合的研究方法,对某巧克力成品库房的溶液调湿空调系统进行性能现状测试与优化潜力分析。研究结果表明,相比于常规的冷冻除湿系统,溶液系统在供冷季的碳减排率可达10.3%。由于小湿差大风量的空气处理特征,系统风机能耗高达近50%,仅考虑热湿处理过程冷热源能耗的优化原则无法实现系统整体性能最优,二次回风系统有助于实现系统性能最优,一次回风与二次回风风量的最优比值区间为0.4~1.5。

基于疏水微孔膜的溶液除湿型地冷空调研究

针对地冷空调室内空气常规除湿方法能耗较高、可能污染室内空气等问题,设计了基于疏水微孔膜的溶液除湿型地冷空调,利用疏水微孔膜把空气与除湿溶液隔开,利用制冷单元排出的余热实现除湿溶液再生,具有能耗低、对室内空气无污染、除湿溶液无损耗等特点;介绍了空调系统的总体流程,并以100m^(2)家庭住宅建筑为例,给出了系统中主要部件和材料的选型和设计参数;建立了系统的特性参数方程,以地板有效面积80m^(2)、室外空气35℃、相对湿度50%、室内空气28℃、相对湿度60%为背景,对系统运行特性进行了计算分析,得到了一组较佳的运行参数,可使系统制冷系数达4.4,室内空气除湿速率达0.153g/s(0.55kg/h),可较好地满足室内制冷和除湿的要求。

Moisture transfer resistance method for liquid desiccant dehumidification analysis and optimization

The concepts of entransy, entransy dissipation and transfer resistance are introduced into liquid desiccant dehumidification analysis to reveal the irreversibility and moisture transfer resistance between moist air and liquid desiccant.By analyzing a typical water (vapor) transfer process coupled with heat transfer, we define the concepts of mass entransy of water and its dissipation, derive the expression of moisture transfer resistance (MTR) that reflects the irreversibility of water transfer during dehumidification processes, and also point out the relationship between MTR and dehumidification performance. With these concepts, both adiabatic and internal cooling liquid desiccant dehumidification systems with various operation conditions are analyzed and optimized. It is found that for the adiabatic dehumidification system, increasing the mass transfer coefficient leads to the reduction of MTR, and consequently, the improvement of dehumidification performance. Meanwhile, for the dehumidification system with internal cooling, in order to reduce the MTR and improve the dehumidification performance, pre-cooling should be centralized ahead of the liquid desiccant inlet when the flow rates ratio of air to desiccant is small, whereas, uniform cooling should be applied when the flow rates ratio of air to desiccant is large.

不同工质在溶液除湿真空再生系统中的性能对比

对一种溶液除湿真空再生系统进行了实验及模拟研究,实验对比了LiCl溶液及CaBr_(2)∶CaCl_(2)=1∶1(溶质的质量分数比)混合溶液的系统性能,发现两溶液的出口含湿量及COP较为接近,当驱动温度为62℃时,系统COP均为0.65左右。通过模拟研究发现,两种溶液的除湿能力十分接近,混合溶液的COP略高于LiCl溶液。驱动温度84℃时,采用混合溶液的出口含湿量为6.0 g/kg左右,系统COP为0.81左右。进口含湿量越高,系统COP将会越高,得益于混合溶液较小的比热容,其再生溶液的耗热量略低,因此其COP略高于LiCl溶液。在此类溶液除湿系统中,CaBr_(2)∶CaCl_(2)=1∶1混合溶液能较好地替代LiCl溶液,实现低成本,高性能。

Experimentation of a Membrane-based Concentration Gradient Energy Storage of Liquid Desiccant Solutions Driven by Solar Energy

Solar energy storage is an indispensable and sustainable utilization mode of renewable energy;environment friendly,large-capacity,low heat loss,and long-term storage are critical to improving the integration of solar energy supply.Traditional thermal energy storage mode cannot achieve long-term storage due to the heat loss even under the excellent thermal insulation measures.In this work,a solar-powered membrane-based concentration gradient energy storage of liquid desiccant solutions is presented.In the membrane distillation process driven by solar energy under the right solar radiation conditions,the liquid desiccant solution is concentrated gradually and long-term stored as the concentration gradient energy.To this end,the measured temperature of solar hot water is in the range of 40°C to 90°C from May to September,2018,in Xi’an,China.And then,the LiBr solution(50 wt%),the LiCl solution(35 wt%),and the CaCl_(2)solution(40 wt%)were membrane-based concentrated in the temperature range of 42°C to 63°C,separately.The results showed that the water vapor pressure difference decides the water vapor transferred across the membrane pores from the liquid desiccant side to the air side.The energy storage density of liquid desiccant solutions increases along with the increases in temperature and the membrane area.Consequently,when the LiBr,LiCl,and CaCl_(2)solutions are concentrated from 50%to 55%,from 35%to 40%,and from 40%to 45%,separately,the concentration energy storage density is 245 kJ/kg,350 kJ/kg,and 306 kJ/kg,which is equivalent to or even higher than ice storage capacity.Due to the two independent closed cycle of the liquid desiccant solution and air,the liquid desiccant solution’s concentration gradient energy storage can be long-term stored environment-friendly without any insulation measures.

溶液除湿系统全热回收装置的优化

提出基于溶液除湿系统中热质交换器数学模型的全热回收装置的理论研究。以笔者所在公司设计研发的3 000 m~3/h热泵热回收型溶液除湿试验装置为研究对象,对全热回收装置进行理论分析:确定全热回收装置结构为液封盒式单泵多级结构;用液封盒结构代替了原有的管路液封设计,理论计算结果,全热回收效率最高可提高24.2%。

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 。

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 1 8～ 2 1℃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COP的冷水机组。溶液除湿方式还可实现高密度的能量蓄存 。

温室吸湿剂喷淋除湿降温系统的影响因子分析

为了解决湿热地区夏季温室的降温问题,提出了利用CaCl2溶液除湿降温系统对温室进行降温的方法。在CaCl2溶液除湿降温系统运行条件下,确定了以喷淋室出口空气相对湿度为试验指标,分析了进口空气流量、除湿剂流量、除湿剂浓度和温度、进口空气温度和湿度等因子对试验指标的影响。通过影响因子的单因素试验和多因素正交试验,得出了系统运行时影响除湿效果的显著因素是除湿剂浓度和温度、进口空气温度和湿度。通过回归分析建立了CaCl2溶液喷淋除湿的数学模型,并通过试验验证了该模型的最大相对误差小于5%。该文为中国南方高温高湿的温室夏季降温提供参考。

湿度独立控制空调系统的工程实践

结合实际工程介绍了一个以溶液处理新风实现湿度独立控制的空调系统 ,对系统的运行情况进行了测试 ,根据测试结果提出了一种送风含湿量的控制策略。测试结果表明 ,在室外潮湿的情况下 ,溶液除湿机组提供的冷量约占所需冷量的 5 0 % ;在室外相对干燥的情况下 ,除湿机组提供的冷量约占所需冷量的 40 %。与传统电压缩制冷系统相比 ,当电热价比值为3时 ,湿度独立控制的空调系统可减少 2 0 %的运行费用。

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 。

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 。