高温热泵转轮除湿及辐射供冷空调系统性能研究

本文提出将高温热泵转轮除湿及辐射供冷复合空调系统应用于高温高湿地区,解决辐射顶板表面结露严重的问题。系统将高温热泵转轮除湿的新风空调系统与室内辐射供冷系统结合,高温热泵转轮除湿空调系统提供低含湿量的新风送入房间,承担全部潜热负荷和新风负荷,辐射板承担显热负荷,对系统进行了热力学分析,分析表明系统能达到送风状态点。应用Airpak软件数值模拟研究了送风湿度对顶板结露和人体舒适度的影响。结果表明室内设计状态点温度26℃、相对湿度45%,辐射板下方能形成一层干燥的空气保护层,将辐射板与空间下部高湿气流隔开,房间平均PMV-PPD值分别为0.48/22%,满足人体舒适性要求。     

基于Cromer循环转轮除湿复合空调系统的性能分析

Cromer循环转轮除湿复合空调系统将转轮除湿与表冷器冷却除湿有机地结合起来,转轮除湿实现系统内部的水分转移,表冷器的冷却除湿把全部湿负荷排到外部环境。本文介绍了Cromer循环转轮除湿复合空调系统的工作原理及特点,给出了其与直接冷却除湿处理新风的比较实例。结果表明,在相同供冷水温度下,该复合空调系统能比直接冷却除湿系统实现更低的送风露点温度,提高表冷器的除湿能力;考虑低温新风可以承担室内显热冷负荷,二种新风处理方法对总的节能性没有影响,但前者送风温度接近13℃且低湿,送风品质更高。该方法可以改善室内空气品质,与直接冷却除湿方法相比不增加制冷能耗,且切实可行,值得进一步研究推广。     

GHP与除湿相结合的复合空调系统

介绍了一种燃气发动机热泵（GHP）与除湿转轮的复合空调系统，夏季将回收的发动机余热用于除湿转轮再生、承担湿负荷；冬季通过排热回收减小空调系统的采暖负荷。对比了复合空调系统、单独使用GHP、电动空调系统的能耗情况。     

太阳能液体除湿处理热湿地区冷却顶板新风湿负荷

以广州为例分析了热湿地区冷却顶板空调系统新风冷负荷的特点,显示夏季空调期新风湿负荷占新风总负荷的90%以上.提出了利用太阳能液体除湿处理冷却顶板空调系统新风湿负荷的方案,并将其与常规的冷却除湿方案进行了比较.结果显示,冷却顶板空调系统新风湿负荷的太阳能液体除湿方式比冷却除湿方式节能40%以上,静态投资回收年限为2.2年,认为冷却顶板空调系统新风湿负荷的太阳能液体除湿方式要优于冷却除湿方式.     

硅胶-氯化锂复合干燥剂除湿转轮性能优化

根据硅胶-氯化锂复合干燥剂除湿转轮的传质传热模型,分析了复合干燥剂除湿转轮运行参数、结构参数、物性参数对转轮除湿量的影响,提出了优化转轮除湿性能的途径。     

夏热冬冷地区近零能耗居住建筑除湿需求分析

以夏热冬冷地区典型近零能耗居住建筑和常规建筑为研究对象,采用De ST计算软件对比研究了夏季和除湿期的热、湿负荷特征,讨论了该地区近零能耗居住建筑适宜的除湿系统形式。研究结果表明:1)由于近零能耗建筑围护结构传热系数较低,随着照明和设备功率密度设计参数的减小,夏季和除湿期的典型日显热负荷分别降低约45. 3%和79. 7%;围护结构气密性的提高可降低约22. 1%的显热负荷和湿负荷,近零能耗居住建筑显热负荷的降低程度明显高于湿负荷; 2)近零能耗居住建筑的热湿比降低为常规建筑热湿比的60%左右。常规空调形式在近零能耗居住建筑中难以同时满足室内温、湿度环境要求,温、湿度独立控制空调系统拥有更好的应用前景; 3)温、湿度独立控制空调系统新风送风含湿量在除湿期低于夏季,冷凝除湿系统能效较低。热泵型空调器与除湿转轮联合运行的除湿空调系统更容易满足近零能耗居住建筑健康性、舒适性和节能性的要求。     

一种新型转轮除湿与双级热泵耦合空调系统及系统设计

本文提出了一种新型转轮除湿与双级热泵耦合的空调系统,首先采用热湿负荷独立处理的思想,利用双级热泵来满足室内冷负荷和转轮再生负荷的要求,而后建立了系统的物理模型并对该系统的性能参数进行了计箅和分析,在满足室内热湿负荷和转轮再生负荷的要求下,双级热泵的2台机组均可同时工作在较高效率范围内.从节能、环保和室内空气品质的角度分析,该系统具有很大的发展潜能.     

除湿转轮效率研究

分析了目前除湿转轮效率定义存在的问题,提出了一种新的转轮效率定义.建立了一维非稳态氯化锂除湿转轮的数学模型,计算得到了不同再生空气温度、含湿量和不同处理空气温度、含湿量下的除湿转轮的除湿量及效率,并与文献实验结果进行对比,结果较为吻合.当转轮效率取0.85时,计算值与实验值的误差在±20%以内,且大部分值的误差都在±10%以内.     

转轮除湿与单元式空调机相结合的空气处理系统

本文介绍了转轮除湿与直接膨胀式单元机组相结合的复合空调系统的2种紧凑型组成形式:前置预冷与后置冷却,并在几种不同室外工况下,针对应用于独立新风系统,对比分析了这2种典型组成方案的性能特点。结果表明,这2种除湿方式在4种典型工况下的制冷能耗相差不明显,在10%以内;但后置冷却除湿在高温高湿工况下难以实现较大的单位除湿量,且再生空气温度高;而前置预冷除湿系统采用较小的除湿转轮尺寸,结构更紧凑,可明显降低初投资,且再生空气温度较低。因此,前置预冷除湿系统在较小流量空气处理应用方面更具优势,更具商品化发展潜力。     

采用冷冻除湿的温湿分控户式空调系统的送风分析

采用冷冻除湿的温湿分控户式空调系统,可将室内显热负荷与湿负荷分开处理,采用辐射方式处理显热负荷,送风承担湿负荷,同时也承担一部分室内显热负荷。因此,如何选定合理的送风温度和送风量是需要解决的问题。本文首先以送风承担室内显热负荷最小为目标,计算最佳的送风量及送风温度;然后,研究在不同的室内湿负荷条件下,送风量对送风承担室内负荷以及空调系统能耗的影响,考虑室内人员对新风的要求后,得到合理的送风温度;最后,计算了采用冷冻除湿的温湿分控空调系统的能耗,与常规温度控制空调系统的能耗进行比较,得到了在合理的送风温度下,如果采用新风处理室内湿负荷,温湿分控空调系统比常规温度控制空调系统节能11%~46%,如果采用回风处理室内湿负荷,则温湿分控空调比常规温度控制空调系统节能21%~46%。     

固体转轮除湿与冷凝除湿的适用性研究

针对不同工况,对固体除湿转轮进行吸湿与再生的性能实验;根据实验结果,采用空气源热泵作为冷热源,通过理论计算得出不同条件下固体转轮除湿与冷凝除湿两种方式的性能。结果表明,相同工况除湿量相同时,转轮除湿相对于冷凝除湿功耗大、效率低;随着室内空气湿度的增大,2种除湿系统能耗都减小,效率增大,冷凝除湿效率改善更明显;室外空气湿度增大,对冷凝除湿性能影响较小,转轮除湿功耗变大,效率降低;室外空气温度升高,冷凝除湿功耗增大,转轮除湿功耗减小,但两者的效率均增大。     

Desiccant wheels as gas-phase absorption (GPA) air cleaners: evaluation by PTR-MS and sensory assessment

Two experiments were conducted to investigate the use of the co-sorption effect of a desiccant wheel for improving indoor air quality. One experiment was conducted in a climate chamber to investigate the co-sorption effect of a desiccant wheel on the chemical removal of indoor air pollutants; another experiment was conducted in an office room to investigate the resulting effect on perceived air quality. A dehumidifier with a silica-gel desiccant wheel was installed in the ventilation system of the test chamber and office room to treat the recirculation airflow. Human subjects, flooring materials and four pure chemicals (formaldehyde, ethanol, toluene and 1,2-dichloroethane) were used as air pollution sources. Proton-Transfer-Reaction--Mass Spectrometry (PTR-MS) and sensory subjects were used to characterize the effectiveness of chemical and sensory pollution removal of the desiccant wheel. The experiments revealed that all the measured VOCs were removed effectively by the desiccant wheel with an average efficiency of 94% or higher; more than 80% of the sensory pollution load was removed and the percentage dissatisfied with the air quality decreased from 70% to 20%. These results indicate that incorporating a regenerative desiccant wheel in a ventilation system is an efficient way of removing indoor VOCs. PRACTICAL IMPLICATIONS: This study may lead to the development of new air cleaners and validates a new concept for the design of ventilation systems that can improve indoor air quality and reduce energy consumption.     

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.     

Modeling and simulation of desiccant wheel for air conditioning

This paper presents the modeling of a desiccant wheel used for dehumidifying the ventilation air of an air-conditioning system. The simulation of the combined heat and mass transfer processes that occur in a solid desiccant wheel is carried out with MATLAB Simulink. Using the numerical method, the performance of an adiabatic rotary dehumidifier is parametrically studied, and the optimal rotational speed is determined by examining the outlet adsorption-side humidity profiles. The solutions of the simulation at different conditions used in air dehumidifier have been investigated according to the previous published studies. The model is validated through comparison the simulated results with the published actual values of an experimental work. This method is useful to study and modelling of solid desiccant dehumidification and cooling system. The modeling solutions are used to develop simple correlations for the outlet air conditions of humidity and temperature of air through the wheel as a function of the physically measurable input variables. These correlations will be used to simulate the desiccant cooling cycle in an HVAC system in order to define the year round efficiency.     

某高压电机装配车间环境控制的实测分析与研究

通过对某高压电机装配车间进行实测,研究了空调风量对恒温恒湿车间工作区空气温湿度均匀性的影响;并与对空调冷负荷的分析相结合,进一步明确影响室内空气湿度最重要的因素是新风,影响室内空气温度最重要的因素是厂房内的工艺设备的散热量;根据高压电机生产车间的低湿环境要求,综合考虑技术性和经济性,对空调湿负荷的处理方式进行了优化研究,提出冷却除湿+转轮除湿复合除湿系统是能够达到此要求的最优化方法.     

Comparison study of a novel solid desiccant heat pump system with EnergyPlus

The variable refrigerant flow (VRF) air conditioning system usually needs to be operated with a ventilation system, since the VRF system cannot provide fresh air. The commonly used ventilation unit with the VRF system is the heat recovery ventilation (HRV) unit due to its merits of energy saving. In this study, a novel solid desiccant heat pump unit (DESICA) is introduced and mathematical model of DESICA is developed based on the dynamic building energy simulation software—EnergyPlus. The mathematical model is validated with experimental results. Based on the model, performance comparison study is conducted among the novel joint DESICA and VRF (DES&VRF) system, the conventional joint HRV and VRF (HRV&VRF) system, and the original VRF standalone with ventilation (VRFSA) system in an office building in Shanghai. Simulation results show that, HRV&VRF and VRFSA can handle the sensible load, though both of them cannot well deal with the latent load. On the contrary, DES&VRF system can keep both indoor temperature and humidity ratio at the target value, resulting in the best indoor thermal comfort than the other two systems. In addition, through the whole year, DES&VRF consumes 5% more energy than VRFSA and 20% less energy than HRV&VRF.     

热泵驱动的双级溶液调湿新风机组原理及性能测试

介绍了一种新型热泵驱动的双级溶液调湿新风机组的工作原理和全年运行方式,重点介绍和分析了该机组主要部件的实测性能数据.测试结果表明,双级溶液全热回收单元的全热回收效率和潜热回收效率分别为55%左右,而新风机组在满负荷工况下整机COP为5.0,部分负荷下可超过5.9,其中的热泵制冷系统在满负荷工况下COP为4.01,部分负荷下可超过5.72,溶液热回收板式换热器的显热回收效率在80%以上.测试分析了机组进行新风处理的整体性能,指出了在再生单元补水的重要性.     

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.     

Performance of combined displacement ventilation and cooled ceiling liquid desiccant membrane system in Beirut climate

The performance of the chilled ceiling (CC) displacement ventilation (DV) systems is constrained by latent load removal capacity and cost of supply air dehumidification to prevent condensation on the ceiling. In this study, a liquid desiccant dehumidification membrane cycle (LDMC) is mathematically modelled to replace the CC and remove directly latent and sensible load from indoor space through the membrane. The desiccant system is coupled with the DV system. An optimized operational strategy is adopted while allowing ceiling temperature to drop to lower values than conventional CC/DV. The optimized LDMC-C/DV system was implemented in an office space in Beirut climate. It was found that decreasing the membrane liquid desiccant temperature resulted in a significant decrease in the total cooling energy of the system, while increasing the solar heating energy of the desiccant regeneration. At optimal set points, a decrease of 49% in energy consumption was observed compared to the conventional CC/DV system.     

冰蓄冷低温送风空调系统(火用)损因素分析

低温送风空调系统引进新型冰蓄冷设备,采用正丁烷作为制冷剂,制冷剂与水直接接触,换热更强烈且稳定。为了研究该系统相应损因素条件下的节能薄弱环节,实现系统性能优化,基于该系统及各表冷器分析模型,分析了热湿比、新风比、送风温差等损因素对系统效率和各表冷器损率的影响。结果表明：当热湿比变化时,处理二次混风的表冷器损率随之呈正比变化,其他表冷器损率及系统效率随之呈反比变化;当新风比变化时,处理新风的两级表冷器损率随之呈正比变化,其他表冷器损率及系统效率随之呈反比变化;当送风温差变化时,处理一次回风的表冷器损率随之呈正比变化,其他表冷器损率及系统效率随之呈反比变化。