吸附式空调的性能研究

1引言近年来固体吸附式制冷或热泵得到了制冷工程研究领域的普遍关注,已有各种吸附式制冷机／热泵被开发研制的报导,其中大多数是活性炭一甲醇、分子筛一水、硅胶一水、氯化钙一氨以及金属氢化物一氢等。其中比较典型的有太阳能热利用的间隙式制冷机［‘］、回热型循环制冷机［‘］和复叠式制冷系统［’］。新的热力循环,如热波型制冷循环l‘］和对流热波型制冷循环问也在不断研究探索之中。对吸附式制冷的研究兴趣主要在于这种制冷方式没有CFCS方面的问题、其价格效用比高、结构简单、与吸收式制冷系统比不需溶液泵或分馏装置,另外它…     

回热型吸附式制冷系统的实际循环与循环周期分析

1前言在吸附式制冷系统中，许多因素影响着系统的实际运行，包括运行工况、实际循环与理想循环的偏离程度、循环周期以及工质对的匹配等。要进行系统的设计，并最大限度地利用所设计的机组，就必须首先考虑这些因素。本文以连续回热型吸附式制冷系统为例，分析了系统运行的循环周期，以及实际循环偏高理想循环这两个主要因素，得出了相应的结论。2连续回热型吸附式制冷系统的实际循环和理想循环基本的回热型吸附式制冷循环包括两个吸附器，它的流程图见图1。在这个系统中，阀A、B、C、D交替开启关闭，吸附器1和吸附器2分别加热和冷却，使…     

传热与传质性能对余热吸附制冰机的影响

文中选用甲醇为制冷剂,对散装活性炭与块状活性炭的吸附式制冰在传热、传质方面进行了试验对比研究,结果表明,散装活性炭在有回热回质条件下COP可以大幅度提高。块状活性炭的传热系数远远好于散装活性炭。在块状活性炭吸附床的传质问题解决后,每个吸附床的吸附剂为48 kg时,两床系统有望实现日制冰600 kg。     

连续回热型吸附式热泵的动态仿真与实验

本文以连续回热型吸附式制冷系统为研究对象,对吸附床及其相关部件进行了动态仿真,从动态分析中,获得了系统循环周期、热源温度对系统运行性能的影响,同时将计算数据与实验数据进行了比较,为今后系统的设计计算提供了可参考的依据。     

连续回热型吸附式空调实际运行与吸附床性能分析

近年来,我们研制了一台连续回热型吸附式空调／热泵,该空调／热泵在１００℃热源驱动下,单位质量制冷功率 ＳＣＰ可达到 １５０ Ｗ／ｋｇ,与此同时 ＣＯＰ达到 ０．４。在系统的实际运行中,吸附床起到了重要的作用。本文介绍了该机组在实际运行中为稳定工况所采取的一系列措施,以及机组运行的实际Ｃｌａｐｅｙｒｏｎ图,着重讨论了系统运行参数对吸附床性能的影响。     

跨声速任意迴转面叶栅流分区计算

本文进一步发展了文献[1]的方法:通道激波前超声区用特征线法,栅前外伸弓形波采用自动伸展;通道波后亚声或跨声区用文献[2]给出的弱守恒流函数方程、引入人工密度、用中心九点差分格式离散主方程、矩阵分解法解出{ψ}场,由文献[2]的办法决定.{ρ}场;迥转面上几个典型算例表明了本方法的工程实用性.文中讨论了τ、Δs、Ω等对流场的影响;捕获了通道波后仍是跨声流时的激波,气流穿过这道波时参数的突跃已明显反映在计算结果中.     

固体吸附式制冷中热波循环的分析研究

1引言由Tehernev博士和S．V．Shelton教授提出的热波循环，是吸附式制冷中引起广泛兴趣的一种循环方式。其特点是高效回热，Shelton采用斜波法［‘］和方波法［‘］分析了热波循环，回热率达70％，热泵工况COP超过1．6。其它学者作了改进研究［‘并热波循环的模拟效果很好，但实验方面进展相当缓慢。采用螺旋板式换热器作吸附器，也发现热波循环的运行效果很不理想问。目前，相关的文献主要是系统模拟，而对其关键，热波的形成、特性研究较少。另外，研究侧重于系统性能（COP），对能量密度（SPD）考虑较少。本文将从传热的角度分析热…     

活性炭-甲醇吸附制冰机的循环特性分析

所研究的吸附式制冰机以块状活性炭和甲醇为工质对,采用烟气加热。研究表明,对于本系统,双床循环较为合 适;双床循环中回热回质过程可以有效的改善吸附床的工作性能以及系统的热力完善度,并能将系统的制冷功率提高7％ 到11％。在循环时间为50 min时,回热回质条件下制冷功率为2 kw左右,可以实现每小时制冰15 kg左右。     

微重力下两同轴液柱内的热毛细对流的渐近解及数值模拟

1引言获得高质量、大体积单晶体对理论研究和实际工业应用都极其重要。由温度梯度引起的表面张力梯度所诱发的热毛细对流对晶体生长不利。zer等人山的空间实验证实，时相关的热毛细对流将引起熔质分凝，带来杂质条纹。人们急需有效抑制热毛细对流的方法。近年发展起来的液封技术在抑制热毛细对流方面表现出诱人的前景［‘－’］。本文着重研究两不相溶混的轴对称同轴液柱内的热毛细对流，通过分析求解及数值模拟，找出了外层流体对内层流体运动的抑制规律，为浮区晶体生长提供一定的理论和实践指导。2物理模型和数学模型如图1所示，距离为L…     

环形液层内热毛细对流的线性稳定性分析

为了了解液层深度对热毛细对流不稳定性的影响,利用线性稳定性理论分析了内径为20 mm、外径为40 mm、深度为1～20 mm的环形液层内硅油(Pr=6.7)的热毛细对流,重点考察了发生热流体波的临界温差及热流体波的临界周向波数,结果表明,临界温差随液层深度的增加而降低.讨论了浮力对热流体波及其临界条件的影响,并证实了常重力条件下当液层厚度大于5 mm时,热流体波呈静止状态这一现象.     

Evaluation of the ice ratio formed during quasi-adiabatic pressure shift freezing

Abstract

Pressure shift freezing consists in cooling a biological substance (mainly containing water) under pressure without phase change followed by a sudden release of the pressure. The high supercooling obtained during the quasi adiabatic depressurisation permits to achieve a rapid and uniform ice nucleation. The ice fraction formed during the pressure release of a sample of pure water has been calculated using a mathematical model. In addition, this fraction was experimentally evaluated by isothermal calorimetry. The calculations and measurements were carried out at 3 different initial points of the ice I melting curve. A relatively good agreement is observed between the experimental and calculated ice ratio which were between 0.117 and 0.402 (kg ice/kg ice-water mixture) for an initial temperature-pressure values of -10°C/1 15 MPa and -21°C/210 MPa respectively.     

Low energy spin dynamics in the spin ice Ho2Sn2O7

The magnetic properties of Ho(2)Sn(2)O(7) have been investigated and compared to other spin ice compounds. Although the lattice has expanded by 3% relative to the better studied Ho(2)Ti(2)O(7) spin ice, no significant changes were observed in the high temperature properties, T is more or approximately equal to 20 K. As the temperature is lowered and correlations develop, Ho(2)Sn(2)O(7) enters its quantum phase at a slightly higher temperature than Ho(2)Ti(2)O(7) and is more antiferromagnetic in character. Below 80 K a weak inelastic mode associated with the holmium nuclear spin system has been measured. The hyperfine field at the holmium nucleus was found to be ≈700 T.     

分离式螺旋热管蓄冰过程动态特性模拟

在提出分离式螺旋热管蓄冷空调系统的基础上,建立了螺旋热管蒸发段蓄冰过程的理论模型,分析了单位时间内管外结冰厚度、管外冰层厚度、蓄冰率、单位时间蓄冷量以及系统总蓄冷量随时间的变化关系,并对三种不同管径的螺旋热管的蓄冰特性进行了分析研究,研究结果表明在螺旋热管曲率半径相同的条件下,增大管径可以提高系统的单位时间蓄冷量。     

Characterization of lysozyme films produced by matrix assisted pulsed laser evaporation (MAPLE)

Thin lysozyme films of thickness up to more than 100 nm have been produced in a dry environment by MAPLE (matrix assisted pulsed laser evaporation) from a water ice matrix. Analysis of the films demonstrates that a significant part of the lysozyme molecules is transferred to the substrate without decomposition and that the protein activity is preserved. The film deposition rate for 1 wt% lysozyme has a maximum at 2 J/cm² of about 1 ng/cm² per laser shot. During the film production the deposition rate is constant without any sign of depletion or accumulation effects in the water ice target or in the growing film. Scanning electron microscopy (SEM) images demonstrate that the silicon substrate is completely covered by lysozyme films thicker than 100 nm. Deposition was also made from a target with pressed (100%) solid lysozyme, but the deposition was difficult to handle and with a much slower rate than that from a water ice matrix.     

Tube reactors as a novel ultrasonication system for trouble-free treatment of sludges

The performance of a novel low-maintenance tube reactor for ultrasonic treatment of sludge has been evaluated. The effects of sonication on the release of soluble chemical oxygen demand (sCOD) and anaerobic digestibility of raw and digested sewage sludge as well as agricultural sludge were studied. Results suggest that solubilization and digestibility is dependent on both type of sludge and the energy input. Digested and raw sludge showed high degree of solubilization, however, methane production was only increased for digested sludge. Agricultural sludge was not significantly affected by ultrasonic treatment neither concerning sCOD release nor methane production. The configuration of the ultrasonic system (serial vs. parallel operation) did not show a significant difference in both sCOD release and methane production. However, parallel operation tends to perform better for digested sludge, while serial operation tends to perform better for raw sludge. The strongest effect was observed for the treatment of digested sludge by increasing the methane production by more than 60%, although with a very intensive energy input of more than 5,000 kJ per kg total solids. Hence, tube reactors seem to be an attractive alternative to sonotrode-based systems achieving similar performance at low maintenance with great potential especially for digested sludge.     

基于ZigBee的高速公路结冰信息检测系统的设计

针对高速公路上结冰状况仅靠驾驶员观察易导致事故的现状,根据结冰温度和冰的导电性,并结合光在冰层中的传播特性,提出一种利用ZigBee技术的新型的高速公路路面结冰信息检测系统。该系统以楔形光纤作为光的传播媒介,通过采集光纤内光强的变化,结合温度和阻值的大小来融合出高速公路上冰的冰厚和冰型。介绍温度、阻值和光强等采集模块的设计原理,及实验测试环境的实现。经过验证,该系统可有效检测出路面的冰厚和冰型。     

Energy conservation in commercial air conditioning through ice storage and cold air distribution design

This paper investigates the feasibility of the application of ice storage/cold air distribution based air conditioning systems in commercial buildings in the South-Eastern Mediterranean area. An office building currently under construction in Nicosia, Cyprus, has been used as an example in the feasibility study. The objective of the study is to compare the performance of the ice storage/cold air distribution system with conventional all air systems in terms of their capital and running costs using current Cyprus Electricity Authority supply regulations and tariff structures. The results show that the application of ice storage combined with cold air distribution will lead to slightly lower capital cost than the conventional system and would result in significant energy cost savings over the life cycle of the system. Changing current Electricity Authority regulations to allow the same equipment to be operated both on-peak and off-peak tariffs will increase further the first cost advantage of the ice storage/cold air distribution air conditioning system over the conventional system.     

High-energy pulse-burst laser system for megahertz-rate flow visualization

A high-pulse-energy megahertz-repetition-rate Nd:YAG-based pulse-burst laser system has been developed. The laser can produce a burst of more than 30 pulses, with an average energy per pulse of 70 mJ, at up to 1-MHz repetition rate. The burst repetition rate is 9 Hz. Coupled with a megahertz-framing-rate CCD camera, the frequency-doubled pulse-burst laser system has been successfully used in the visualization of shock evolution in a supersonic flow.     

A dislocation-based model for creep recovery in ice

Creep recovery strain is significant in polycrystalline ice, and its stress dependence is strongly dependent on ice type and deformation history. Although it is generally recognized that creep recovery strain is largely attributable to dislocations, a dislocation-based model that rectifies the observed differences in two important ice types (freshwater and sea ice) has not previously emerged; and the development of such a model forms the goal of the present effort. The model considers basal dislocation distributions, employs a dislocation density–stress relationship from previous work, and uses an empirical expression for the decrease in slip-line spacing with increasing stress. The dislocation processes are taken to operate over a subgrain-sized domain, and the strain associated with the relative motion of neighbouring domains is considered. The model accounts for dislocation multiplication and the decrease in slip-line spacing if the applied stress is sufficiently high. The model explains the observed differences in creep recovery strain for freshwater and sea ice and adequately reproduces both the stress dependence and the limiting value of the experimentally observed behaviour. It also reproduces the shift from nonlinear to linear behaviour that has been observed in prestrain experiments on freshwater and sea ice cores.