直接接触式二元冰蓄冷系统的实验研究

二元冰(Binary Ice)是当前蓄冷空调使用的新型介质,有着极为广阔的应用前景.文中介绍了二元冰的几种制备方式,包括喷射式、刮削式、过冷式、真空式和下降膜式等;以实验、开发为目的,着重阐述了直接接触式二元冰蓄冷系统的基本原理、方法及其优点.     

二元冰吸收式制备技术

二元冰具有优异的传热、流动特性,使用它后能够减小热交换器的热损失、水泵的能耗和设备体积等,优化热交换器的结构.吸收式制冷可以利用热能为动力,尤其是可以利用低品位热能为动力的优点使其在空调领域得到了较大发展.二元冰吸收式制备技术可以同时兼备这两项优点,但如何有效保持冰晶的尺寸在一定范围之内是该技术目前存在的主要问题,从蒸发器的结构设计和制冷剂性质优化这两方面入手,可以较好的解决这一问题.     

冰浆在蓄冰池中的贮存与融化研究进展

总结分析现有的蓄冰池中冰浆贮存及融化在机理、数学模型、实验方面的研究成果,在此基础上,实验研究了入口冰浆流量、冰浆固相含量、初始液面高度和进水管布置等参数对贮存和融化特性的影响。实验发现使用高浓度的二元溶液、高含量冰浆固相以及增大进口流量都可以使冰浆贮存更均匀;增大融冰溶液的流量、增加扰动以及均匀喷撒溶液是避免"沟道"效应从而实现快速、均匀融冰有效手段。     

海水制取流化冰技术及其在渔业领域的应用

讨论流化冰的技术特点并与传统的冰比较,介绍海水制取流化冰的系统及机组,着重介绍流化冰在渔业领域的应用以及技术研究领域,分析流化冰技术的应用前景。     

防覆冰涂层设计制备及性能研究

介绍了固体表面覆冰及防覆冰机理、防覆冰涂层的制备与表征、防覆冰表面制备的技术难点,并展望了超疏水防覆冰涂层和复合涂层防覆冰在涂料等行业中的应用。     

8＊15冰楼的设计与研究

介绍了具有双组式大型卧式冰库冰楼的主要技术性能、工作原理和流程,贮冰、输冰、称冰系统的结构特点。对贮冰秤、输冰螺旋机的设计计算及混凝土加冰拌和降温效果作了探讨,提出了今后冰楼设计中应注意的一些问题。     

真空法制取二元冰的理论分析

新的蓄冷介质越来越被人们重视,二元冰俗称冰浆是其中一个比较受到人们关注的一种蓄冷介质。制取冰浆的方法有很多种,其中真空法就是其中一种。因为它的制取步骤比较简单,不需要消耗太多的电力能源,同时制取二元冰的效率很高。通过对真空室内下落液滴的质量、速度、温度、下落距离建立微分方程,选定不同的初始条件和真空条件,模拟计算求解。通过对计算结果的比较、分析,明确指出在试验设计时应该选用喷射的液滴初始直径较小的喷头,同时保持真空室稳定在压力较小的环境下。     

三峡工程第一套砼加冰预冷系统的设计和使用

阐述了三峡工程第一套砼加冰预冷系统的工作原理、构造以及主要技术参数的确定,并对使用情况作了分析;着重对IS120—60冰库、气力输送片冰装置、输冰螺旋机和称冰装置作了探讨;对照实际使用的经验和尚存的一些问题,提出了切合实际的技术措施,以促使砼加冰预冷技术进一步完善.     

蓄冰空调系统的原理及其发展现状

近几年,美国、日本、加拿大等国对蓄冰空调系统的研究不断深入,蓄冰空调技术逐步趋向成熟。据估计,在美国新建或改建的空调建筑中,采用蓄冰空调系统的已达20％以上,蓄冰空调机组的制造已变成了一个举足轻重的产业。本文根据这几年国外蓄冰空调技术的研究和应用经验,对蓄冰空调系统及其发展趋势作一个比较深入的讨论。     

110 kV输电线路覆冰的探讨

输电线路覆冰给电网安全稳定运行带来极大威胁，分析输电线路覆冰发生的物理机理及线路覆冰事故发生的原因，积极探索防冰、防线路舞动措施，融冰的技术，防止和避免覆冰倒塔、线路舞动等事故的发生具有重要意义。     

水制冷系统闪蒸器特性的理论分析

水制冷系统作为一种新型的制冷系统,具有三大优点：１．使用天然制冷剂 ;２．制冷与蓄冰可以实现有机的结合;３可以提供用于输送的二元冰晶。本文对水制冷系统的关键部件之一－闪蒸器内的冰晶形成过程进行了理论分析,建立了数学模型,在无因次分析的基础上做了简化并进行了数值求解,分析了初始速度、闪蒸器内蒸气压、水滴尺寸等因素对结冰率的影响。为了提高水滴的结冰率,减小水滴颗粒尺寸是较为有效的方法。／     

Ultrasonic determination of the particle concentration in model suspensions and ice slurry

The development of ice slurry for refrigeration systems and the enhancement of its efficiency depend on an accurate control of the ice concentration. We present here an ultrasonic method capable to measure precisely the particle concentration in ice slurry. To calibrate the ultrasonic measurement, we first determine the sound velocity and attenuation in two model suspensions (glass beads/polyethylene glycol and polyethylene beads/vaseline oil) for different particle volume fractions. The experimental results show a good agreement with the predictions of the two-component models in the long-wavelength limit. Additionally, the sound attenuation reveals a clear signature of the aggregate formation in the nearly iso-dense suspension. We next conduct the measurement of the sound velocity in the polypropylene glycol ice slurry where the ice concentration changes with temperature. The ice concentrations extracted from our sound velocity measurements are well consistent with the values determined from the binary phase diagram.     

A quantitative evaluation of the production performance of ice slurry by the oscillatory moving cooled wall method

Ice slurry has recently been utilized for a variety of engineering fields such as thermal energy storage and high-density energy transportation. In this paper, as a production method of ice slurry, the oscillatory rotating cooled tube method was proposed. A vertical cooled tube was installed in a test vessel that was filled with ethylene glycol solution being forced to move within an aqueous binary solution to produce the ice slurry. Production performance of ice slurry by the present method was determined under a variety of conditions, such as initial concentration of solution, angular acceleration and rotation angle for the oscillation motion of the cooled tube. The production performance was evaluated analytically by constructing a numerical model. The analysis was made to determine the separation condition of ice layer from the cooled tube surface at first, then the production rate of ice slurry was assessed. It was found from the present study that the ice slurry was produced continuously under the appropriate operating conditions in which the separation of ice layer was caused by oscillating motion of the cooled tube.     

Dependence of the thermodynamic properties of ice slurries on the characteristics of marketed antifreezes

Cold transport by means of two-phase aqueous secondary refrigerant (mixtures of solid ice and liquid water-antifreeze known as slurries) makes it possible to use a leak-proof and compact refrigerating unit, whereas, thanks to the latent heat of ice, the distribution duct diameters are kept within reasonable limits. In order to design such cold distribution plants efficiently, one must know precisely the thermodynamic properties of the slurries, especially the relations that link the temperature, the ice mass fraction, and the enthalpy. In this paper, we discuss the ways of computing the thermodynamic properties of the slurries and we established a method of measurement for the detection of freezing points of water-antifreeze mixtures. We give the first results (obtained from previously published data and from experiments) for binary mixtures based on four widely distributed antifreezes. The dependence of the thermodynamic properties on the characteristics of the antifreezes is discussed.     

霜层生长初期冰晶体分布状况实验研究

研究霜层的结构对于理解结霜现象有着重要的意义。利用自行研制的图像放大及采集系统，对霜层生长初期冰晶体的形态进行显微观测，得到了不同生长条件下冰晶体的图像。随后采用数字图像处理方法，将原图像转换为二值图。通过对图像的分析，发现霜层的生长初期冰晶体的分布与充分生长的霜层有所不同，此时霜层靠近冷表面固含率最大；随着高度的增长，固含率以近似线性的方式减小。实验还发现，对霜层生长初期影响最大的两个因素是冷表面的温度和空气的相对湿度。随着冷表面温度的降低，霜层的高度明显增长，冰晶体沉积量增加，而平均密度的变化则不明显；随着空气相对湿度的增加，霜层的高度、平均密度以及冰晶体总的沉积量都有所增加。空气温度对霜层生长的影响不明显。     

Control of ice chromatographic retention mechanism by changing temperature and dopant concentration

A liquid phase coexists with solid water ice in a typical binary system, such as NaCl-water, in the temperature range between the freezing point and the eutectic point (t(eu)) of the system. In ice chromatography with salt-doped ice as the stationary phase, both solid and liquid phase can contribute to solute retention in different fashions; that is, the solid ice surface acts as an adsorbent, while a solute can be partitioned into the liquid phase. Thus, both adsorption and partition mechanisms can be utilized for ice chromatographic separation. An important feature in this approach is that the liquid phase volume can be varied by changing the temperature and the concentration of a salt incorporated into the ice stationary phase. Thus, we can control the relative contribution from the partition mechanism in the entire retention because the liquid phase volume can be estimated from the freezing depression curve. Separation selectivity can thereby be modified. The applicability of this concept has been confirmed for the solutes of different adsorption and partition abilities. The predicted retention based on thermodynamics basically agrees well with the corresponding experimental retention. However, one important inconsistency has been found. The calculation predicts a step-like discontinuity of the solute retention at t(eu) because the phase diagram suggests that the liquid phase abruptly appears at t(eu) when the temperature increases. In contrast, the corresponding experimental plots are continuous over the wider range including the subeutectic temperatures. This discrepancy is explained by the existence of the liquid phase below t(eu). A difference between predicted and measured retention factors allows the estimation of the volume of the subeutectic liquid phase.     

Evaluation of depth profiling using laser resonant desorption as a method to measure diffusion coefficients in ice

Diffusion of gases in ice is involved in cloud, snow, and ice core chemistry, but few data exist on the relevant diffusion coefficients. A novel method to measure diffusion coefficients in ice has recently been proposed by Livingston et al. (Anal. Chem., 2000, 72, 5590-5599). It is based on depth profiling of doped ice crystals epitaxially grown on Ru(001) by laser resonant desorption (LRD). Using this method, Livingston et al. obtained a value of the diffusion coefficient of the HCl hydrate in ice at 190 K of about 5 x 10(-11) cm2/s. We argue here that this value is many orders of magnitude higher than what could be expected from literature values, which are not reported in sufficient detail by Livingston et al. We investigate the possibilities that their high value could be due to (1) diffusion in defects in the ice, which would be present in very high concentrations because of the ice growth method; and (2) the fact that diffusion of high concentrations of HCl in ice at 190 K forms an amorphous HCl:H2O solid mixture, where HCl diffusion is fast. We present new infrared spectroscopic data on solid HCl:H2O mixtures that confirm that such mixtures can indeed be formed in an amorphous state at 190 K. Our proposed interpretation is that by depositing large amounts of HCl on epitaxially grown ice, Livingston et al. created a superficial amorphous binary mixture and that fast diffusion of HCl in the ice, possibly accelerated by a high defect density, produced an amorphous HCl:H2O mixture. We conclude that the processes studied by Livingston et al. are different from those involved in the atmospheric and cryospheric sciences, and that their data, obtained by depth profiling using LRD, probably cannot be applied to those fields.