一种蜂窝纸砖填料用于除湿液体再生过程的实验研究

本文设计出一种采用新型蜂窝状"纸砖"砌成的填料塔,用来进行除湿溶液在一定工况下与空气的再生试验.在控制溶液浓度、流量以及进口空气状态的条件下,分别研究了空气流量、溶液温度以及填料层高度对溶液再生性能的影响趋势,并分析了各因素对再生性能的控制机理.通过对试验数据的整理,得到了几种填料厚度下平均Sh数的变化规律.     

热泵型溶液调湿新风机组冬季性能试验研究

搭建热泵型溶液调湿新风机组试验台,在冬季工况下,新风温度为9.5~10.1℃,含湿量为2.5~3.1 g/kg干空气时,试验比较填料类型、溶液温度、溶液浓度、溶液再生方式对机组制热加湿性能的影响。结果表明,在比较的3种填料中,7090湿帘填料综合性能最优;加湿单元入口溶液温度为32~34℃,且溶液槽中溶液浓度为45%~48%时,机组性能较好;机组采用回风再生较新风再生时的溶液再生能力提高,溶液槽中冷热抵消现象缓解,机组补水量减少47%,制热性能提高12%。试验结果可为热泵型溶液调湿新风机组的设计与冬季运行控制提供参考。     

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。     

无霜空气源热泵系统除湿与再生工况?分析

为解决传统空气源热泵系统冬季的结霜问题,同时提升夏季机组的性能,本文提出一种"一塔三用"的无霜空气源热泵系统。通过搭建实验台研究了在除湿工况下的空气温度、含湿量、质量流量及溶液温度、质量流量、质量浓度,在再生工况下的溶液质量浓度、温度对溶液塔进出口空气?、除湿?(再生?)、系统输入输出?及?效的影响。结果表明:除湿工况下,除湿?随空气温度、空气质量流量、溶液质量流量的增加以及空气含湿量、溶液温度、溶液质量浓度的减少而增加;系统的?效随空气温度、含湿量、质量流量及溶液质量流量、质量浓度的增加以及溶液温度的减少而增加,其中空气含湿量、溶液质量浓度对?效影响较小,此模式?效最高可达0. 201。再生工况下,再生?随溶液质量浓度、温度的增加而增加;系统?效随溶液质量浓度的增加、溶液温度的减少而增加,其中溶液温度对?效影响较小,此模式?效最高可达0. 108 8。该系统?效率在实验工况下高于常规空气源热泵系统。     

无霜空气源热泵系统冬季再生性能初步实验

本文提出一种新型无霜空气源热泵空调系统,该热泵系统不仅冬季可以无霜高效运行,夏季性能也有所提升。通过搭建该系统实验平台研究了再生模式,并对再生模式的实验数据进行回归分析,拟合得出的关联式相对误差小,拟合度高,再生量的平均相对误差为0. 31%,再生效率的平均相对误差为0. 56%。分析关联式得出溶液塔入口空气流量、溶液温度、溶液流量、溶液质量分数对系统再生性能的影响,发现再生量随空气流量、溶液温度、溶液流量的上升,溶液质量分数的下降而上升;再生效率随空气流量的下降,溶液流量的上升而分别增大26. 00%与13. 63%;再生量随溶液流量的增加升高了26. 30%,随质量分数的增加下降了约6. 10%,溶液温度与质量分数在本文研究范围内影响较小。     

叉流再生器性能试验研究

搭建叉流再生器性能试验台,利用Celdek规整填料作为气液接触介质,再生剂选用LiCl-H2O溶液,选取再生量和再生效率作为再生性能的评价指标。试验分析空气、溶液进口参数对再生性能的影响,并利用试验数据建立适用于LiCl-H2O溶液的再生效率和传质系数的试验关联式。最后将试验结果与文献中的相关结果进行比较,结果表明:不同的再生剂对再生性能的影响基本相同;当溶液浓度较低时(LiCl-H2O溶液≤32%),使用LiCl-H2O溶液比使用LiBr-H2O溶液的再生量大,而溶液浓度较高时,情况反之。     

利用冷凝热再生低浓度除湿溶液的实验研究

为了获得系统重要运行参数对利用冷凝热实现低浓度除湿溶液再生性能的影响,本文在热泵驱动溶液除湿空调系统实验平台上,以低浓度的Li Cl水溶液作为再生盐溶液,再生量和冷凝热利用率作为再生性能的评价指标,对利用冷凝热实现溶液再生过程进行了实验研究。结果表明:空气流量、温度和溶液流量、温度的增加都有利于提高再生量。在夏季典型工况下,当溶液浓度为21.20%~24.91%时,冷凝热利用率在0.416~0.507波动,降低溶液浓度有利于提高冷凝热利用率。并根据实验数据拟合出了利用冷凝热再生除湿溶液过程中的耦合传热传质系数关联式,为后续如何在溶液再生过程中充分利用冷凝热提供了实验依据。     

再生液回流量对溶液除湿系统性能影响的分析

针对热泵型溶液除湿机提出了一种通过改变再生回流量的系统性能优化方案,通过在Simulink中建立除湿机各组件的数值计算模型,从而建立除湿机整体的除湿性能数值计算模型,然后通过数值模型计算不同再生回流量下的除湿机整体除湿性能,得出了最佳再生回流量,在该再生回流量下,除湿机整体除湿性能最高,并根据计算结果总结出了提高热泵型溶液除湿机性能的有效措施。     

无霜空气源热泵系统喷淋溶液质量及浓度变化规律研究

本文提出了无霜空气源热泵系统及其工作过程,根据提出的无霜空气源热泵的原理,进行了喷淋溶液的筛选。分析目前常用的除湿溶液,主要从蒸汽压力、凝固点、粘度、经济性等方面对常用的有机除湿溶液进行比较,最后确定丙三醇（甘油）作为室外换热器的喷淋溶液。通过比较不同溶液浓度和流量对除湿性能及机组性能的影响来找到合理的喷淋溶液的浓度和喷淋溶液的流量。然后使用这个浓度和流量在不同的室外气候条件下向室外换热器喷淋除湿溶液,分析不同室外条件对除湿效果和抑制结霜效果的影响,整理出室外风机风量、室内供热量、输入功率、COP、喷淋溶液截留的水量等参数的变化。最后通过实验数据分析喷淋溶液集中再生的条件,分析不同地区喷淋溶液集中再生的可行性及不同地区集中再生需要的稀溶液罐和浓溶液罐体积,为无霜空气源热泵的应用提供参考。     

具有预凝功能的新型热源塔运行性能的实验研究

为解决现有开式热源塔冬季运行时塔内溶液吸湿量大而影响系统运行安全的缺陷,本文设计了一种具有预凝功能的新型热源塔结构,分析了新型塔的运行过程,并对比研究了新型塔和普通塔在不同进口溶液温度、空气流量和溶液流量下的运行性能。实验结果表明,新型塔具有更强的换热性能和更低的溶液吸湿性。进口溶液温度由1℃上升到3℃时,新型塔的换热量相比于普通塔增加了0.62~0.24 k W,溶液吸湿量平均减少了0.13 g/s;空气流量由1.41 kg/s升高到2.17 kg/s,新型塔的换热量相比于普通塔增加了0.79~0.84 k W,溶液再生量平均增加了0.1 g/s;溶液流量由0.36 kg/s升高到0.68 kg/s,新型塔的换热量相比于普通塔增加了0.57~0.63 k W,溶液吸湿量平均减少了0.11 g/s。     

Air stripping of ammonia in a water-sparged aerocyclone reactor

Air stripping of ammonia is a widely used process for the pretreatment of wastewater. Scaling and fouling on the packing surface in packed towers and a lower stripping efficiency are the two major problems in this process. New equipment that is suitable for the air stripping of wastewater with suspended solids has been developed. Air stripping of ammonia from water with Ca(OH)₂ was performed in the newly designed gas–liquid contactor, a water-sparged aerocyclone (WSA). WSA exhibited a higher air stripping efficiency and an excellent mass transfer performance, it also consumed less air compared with stripping tanks and packed towers. In addition, no scaling and fouling was observed in the inner structure of the WSA. During the stripping process, the stripping efficiency and mass transfer coefficient naturally increases with the liquid phase temperature and air flow rate. There is a critical value for the air flow rate over which stripping efficiency and the mass transfer coefficient increases rapidly. An efficient air stripping of ammonia should be conducted at a higher ambient temperature (>25 °C), and a higher air flow rate (>1.4 l/s).     

Experimental study on a new internally cooled/heated dehumidifier/regenerator of liquid desiccant systems

For providing good performance of dehumidifier and regenerator with certain dimensions, a new type of internally cooled/heated dehumidifier/regenerator based on the plate–fin heat exchanger (PFHE) was designed. To investigate the behavior of the new equipment, an experimental setup was established in an environment chamber with regulable temperature and humidity air. By the internally cooled dehumidification testing, effects of the cooling water temperature, the air flow rate and the desiccant temperature on the dehumidification performance and the cooling efficiency were presented. The behavior of internally cooled dehumidification process was compared with that of the adiabatic dehumidification process. The results suggested that the cooling efficiency decreased with the increasing of the cooling water temperature and desiccant with low temperature could bring more mass transfer coefficients. There is an optimal air flow rate to achieve the maximum absolute humidity decrease of the air. By the internally heated regeneration testing, effects of the air flow rate and the desiccant inlet temperature on the regeneration performance and air outlet parameters were discussed and also compared with those of the adiabatic regeneration process. It was concluded that the regeneration efficiency of internally heated regeneration was more than that of the adiabatic regeneration, and the internally heated regenerator could offer better thermal performance.     

The influence of the magnetic field on the performance of an active magnetic regenerator (AMR)

The influence of the time variation of the magnetic field, termed the magnetic field profile, on the performance of a magnetocaloric refrigeration device using the active magnetic regeneration (AMR) cycle is studied for a number of process parameters for both a parallel plate and packed bed regenerator using a numerical model. The cooling curve of the AMR is shown to be almost linear far from the Curie temperature of the magnetocaloric material. It is shown that a magnetic field profile that is 10% of the cycle time out of sync with the flow profile leads to a drop in both the maximum temperature span and the maximum cooling capacity of 20-40% for both parallel plate and packed bed regenerators. The maximum cooling capacity is shown to depend very weakly on the ramp rate of the magnetic field. Reducing the temporal width of the high field portion of the magnetic field profile by 10% leads to a drop in maximum temperature span and maximum cooling capacity of 5-20%. An increase of the magnetic field from 1 T to 1.5 T increases the maximum cooling capacity by 30-50% but the maximum temperature span by only 20-30%. Finally, it was seen that the influence of changing the magnetic field was more or less the same for the different regenerator geometries and operating parameters studied here. This means that the design of the magnet can be done independently of the regenerator geometry.     

基于多孔陶瓷的体吸收太阳能集热器性能分析

体吸收型太阳能集热器是3种主要的太阳能集热器之一,具有结构简单,效率高等优点,并且出口空气温度可达800℃以上,应用前景广阔。在体吸收太阳能集热器中,采用多孔材料而不是管路来加热工质,入射辐射可以从外到内逐步进行吸收。该文基于多孔泡沫陶瓷材料构建了一个一维体吸收太阳能集热器计算模型,在此基础上,计算分析了不同参数下的温度分布情况及热辐射吸收效率。研究结果表明,随着多孔陶瓷孔隙率的降低,出口空气温度及陶瓷内部气体与固体达到稳定的深度均逐渐降低,而接收器前表面温度逐渐提高;随着孔径的下降接收器尾部气体出口温度逐渐下降,内部气体和固体达到稳定的深度逐渐减小,但由于孔径的减小使得对流换热系数显著上升,因此其前表面的温度变化并不明显。太阳能吸收效率随着空气流速的降低和入口空气温度的增大而明显提高,但随着入射辐射强度的提高而降低。     

溴化锂填料吸收器中绝热吸收过程的实验研究

针对传热、传质分离的填料吸收器，设计、加工了一个溴化锂绝热降膜吸收的循环实验装置；实验研究了溴化锂水溶液在填料层上的绝热吸收特性；分析了溶液温度、浓度、降膜雷诺数对吸收效率和传质系数的影响。