关于氨制冷装置的新动向

关于氨制冷装置的新动向ＴｈｅＮｅｗＴｒｅｎｄｓｏｆＡｍｍｏｎｉａＲｅｆｒｉｇｅｒａｔｉｎｇＭａｃｈｉｎｅｓ费人杰（中国纺织工业设计院北京１０００３７）氨是一种人们很熟悉的制冷剂，已经使用了１２０多年。由于安全方面的要求，氨制冷机逐步被氟利昂制冷机所代...     

吸附式制冷研究概况

介绍了吸附式制冷近期成为研究热点的背景，讨论了基本循环方式及其ＣＯＰ，给出了国产活性炭吸附甲醇的Ｄ—Ｒ方程，提出了几种改善吸附式制冷机性能的方法，最后还介绍了吸附式制冷的发展动向．     

日本氨制冷装置的现状和将来

由于氟利昂问题引发的对氨重新评价，已成为各国制冷业界关注的课题。本人基于作者愿意，摘择如下，供国办制冷技术人员参考。     

重视氨制冷剂在制冷空调上的应用

重视氨制冷剂在制冷空调上的应用中国制冷学会曹德胜ＡｍｍｏｎｉａｔｈｅＣｈａｌｌｅｎｇｅｉｎＡｉｒＣｏｎｄｉｔｉｏｎｉｎｇＲｅｆｒｉｇｅｒａｔｉｏｎ￥ＣａｏＤｅｓｈｅｎｇ氨用作制冷剂在我国历史悠久,亦是用氨作制冷剂的应用大国,特别是冷冻冷藏,在５００余...     

活性炭—甲醇吸附式制冷循环的研究

本文选用活性炭作吸附剂、甲醇作吸附介质,从实验和理论两方面研究了吸附式制冷间歇循环效率COP的变化规律。从实验研究的结果中可知,最高解吸温度、吸附温度、冷凝压力和蒸发温度等对COP有不同程度的影响。当最高解吸温度在100℃附近时,COP最大。从理论分析中。导出了COP的表达式,并且COP表达式的计算值与实验结果吻合得较好。     

固体吸附式制冷与空调的发展和应用前景展望

固体吸附式制冷是利用低温热源，在能量回收和节能方面有广阔前景的制冷方法。本文结合国内外的研究成果，对这一新技术进行总结和探讨。     

孔结构分布对活性炭-甲醇工质对吸附制冷特性的影响

本文通过前体物复配、催化炭化、CO₂接触氧化与梯度催化活化相结合的改进工艺,对压块活性炭的孔结构进行原位调控,制备了中微孔同步发达的GHUM型与中孔发达的SX-100型活性炭;以微孔炭GDWK-02为参比,研究了孔结构分布调控对活性炭-甲醇工质对的吸附/脱附特性及制冷性能的影响。结果表明:中微孔同步发达的GHUM炭孔结构促进了对制冷剂的凝聚与扩散作用,对甲醇的吸附量((368.04±4.64) mg/g)、脱附量((375.92±7.38) mg/g)及表面扩散系数(299.32±123.16)较SX-100和GDWK-02均有所提升;且脱附温度为100℃时,GHUM型吸附床内部传热温差高达50℃,制冷室平均温度维持在(23±1)℃,系统制冷量和制冷功率分别可达286.12 kJ/kg、357.65 kJ/(kg·h),满足夏季制冷送风空调系统维持室内恒温的需求,且显示了良好的传热和制冷性能。     

锌基-MOFs对氨吸附制冷性能的分子模拟研究

本文采用巨正则蒙特卡洛(grand canonical Monte Carlo, GCMC)方法,基于UFF(universal force field)和TraPPE(transferable potentials for phase equilibria)力场,对ZIF-8(Zn)吸附NH₃进行了分子模拟研究,并结合分子模拟结果和吸附式制冷热力学循环模型,研究了ZIF-8(Zn)/NH₃工质对的吸附性能和制冷性能。研究表明：在等温条件下,ZIF-8(Zn)对NH₃的吸附量随压力的增大而提高,298 K和398 K下饱和吸附量分别达到0.305 g/g和0.231 g/g;同一温度下的总吸附热也随压力的增大而上升,这主要归因于NH₃分子间相互作用产生吸附热的增加,而ZIF-8(Zn)与NH₃相互作用的吸附热维持在较稳定的状态;NH₃在ZIF-8(Zn)中的吸附密度分布结果表明NH₃在金属位点处被大量吸附,难以通过ZIF-8(Zn)部...     

氯化钙-氨吸附式制冷的实验研究

在以氯化钙-氨为工质对的两床吸附式制冷系统上进行了实验研究,得出了不同热源温度下,以氯化钙-氨为工质对的连续循环制冷系统的制冷量、性能参数COP随时间的变化关系。所得结果可为进一步的实验研究和工程设计提供指导。     

An experimental and numerical study on dynamic characteristic of linear compressor in refrigeration system

This paper presents experimental and numerical results of the dynamic characteristic and COP of a linear compressor in a refrigeration system using R600 refrigerant. The numerical analysis consists of a model and a simulation that includes the linear compressor. In this study, the dynamic characteristic of the natural frequency of the linear compressor is validated by comparing the simulation results with the experimental results. To investigate the effect of system resonance on the performance of linear compressor, COP is evaluated under evaporator pressure in the range of 48.3–63.2 kPa abs, and condenser pressure in the range of 439.0–573.3 kPa abs. Based on the results, the system resonance at the TDC was varied within a range of 3% under the test conditions. COP and its sensitivity were found to vary within 3% according to the operating frequency of the system ranging from 48.5 to 51.5 Hz.     

An experimental study on fatigue characteristics of CFRP-steel hybrid laminates

This paper aims to investigate the fatigue characteristics of hybrid laminates consisting of wave carbon fiber reinforced polymer (CFRP) sheets and a thin stainless steel plate under the tension–tension loading. Different loading options (e.g. same stress and same force), layers of CFRP sheets, and lay-ups of laminates (single and double sides) were considered. A series of experimental tests were performed to determine the effectiveness of the CFRP bonding on prolonging fatigue crack initiation life, preventing fatigue crack propagation and extending fatigue life of the hybrid laminates. Three distinct failure modes, classified as delamination, delamination bending and fiber breakage, were observed in the tests. It is shown that the loading conditions and CFRP thickness are the critical parameters affecting the failure modes and fatigue resistance. The crack initiation life and fatigue life of fiber-metal laminates (FMLs) increase by factors ranging from 1.06 to 1.96 and 1.17 to 2.07, respectively, relative to monolithic steel plates under the same force condition; whereas decrease by factors ranging from 0.63 to 0.89 and 0.28 to 0.61 under the same stress condition. Moreover, the double-side bonded FMLs show better fatigue properties and more stable crack propagation than single-side counterpart with the same thickness of CFRP.     

吸附式制冷工质对的吸附性能测试研究

吸附剂的性能是吸附制冷技术中最重要的参数之一,而吸附量和吸附速率是吸附剂性能的2个重要指标。准确测定吸附剂的性能对于吸附制冷机的设计起着至关重要的作用。本文结合国内外对吸附剂性能的测试方法以及本课题对汽车余热吸附制冷所用吸附剂的性能进行测试,着重阐述吸附剂性能测试所用方法的特点以及使用范围,旨在为吸附剂性能的准确测试提供参考。     

基于磁流变弹性体的缓冲装置设计及其冲击响应特性研究

利用聚氨酯基磁流变弹性体,结合ANSYS有限元仿真,设计制作了一种剪切式磁流变弹性体缓冲装置。搭建自由跌落冲击试验系统和冲击响应谱试验系统分别测试了该缓冲装置的冲击响应特性,研究了在不同磁场下缓冲装置的缓冲性能。实验结果表明在自由跌落冲击和冲击响应谱两种试验中,所设计的磁流变弹性体缓冲装置都具有较高的缓冲率,且装置的缓冲率随着磁场的增加而增大,表明磁流变弹性体缓冲装置起到了一定的缓冲作用,且可以实现外加电流对其缓冲效果的控制,该研究为磁流变弹性体在半主动/主动隔振缓冲领域的应用做出了有益探索。     

金属橡胶的刚度特性和阻尼试验研究

基于金属橡胶内部微元螺旋卷结构,并以弹簧理论建立其力学模型,分析了在螺旋卷之间不同接触("未接触、滑动、压缩")形式下的刚度公式并解释载荷作用下刚度曲线不同阶段的特性。基于金属橡胶的非线性对阻尼进行计算,通过试验研究金属橡胶构件的密度、厚度对静态刚度曲线不同阶段的影响,及在不同振幅、频率下比阻尼随密度和厚度的变化规律,为金属橡胶的设计及工程应用有重要的指导意义。     

Cycling losses in refrigeration equipment: An experimental evaluation

Cycling losses may be defined as those inefficiencies that reduce the performances of units during the transient period. They may be quantified by comparing the Energy Efficiency Ratio (EER) of a cycling unit and the EER of the same unit working continuously.The on-off control is the most widespread strategy for modulating; therefore, a reliable evaluation of cycling losses is fundamental to assess the EER of the system. The mentioned losses have been experimentally evaluated on a test rig, and logged data demonstrate a loss up to 13% with respect to steady operations when the load factor is lower than 10% and a Thermostatic Expansion Valve (TEV) is used. The insertion of a solenoid valve in series with the TEV can reduce the losses but the best results are obtained by using the Electronic Expansion Valve (EEV) instead of the TEV.     

Study on adsorption refrigeration cycle utilizing activated carbon fibers. Part 1. Adsorption characteristics

Thermal heat driven adsorption systems using natural refrigerants have been focused on the recent energy utilization trend. However, the drawbacks of these adsorption systems are their poor performance in terms of system cooling capacity and coefficient of performance (COP). The objective of this paper is to improve the performance of thermally powered adsorption cooling system by selecting new adsorbent–refrigerant pair. Adsorption capacity of adsorbent–refrigerant pair depends on the thermophysical properties (pore size, pore volume and pore diameter) of adsorbent and isothermal characteristics of the pair. In this paper, the thermophysical properties of two PAN types of activated carbon fibers (FX-400 and KF-1000) are determined from the nitrogen adsorption isotherms. The standard nitrogen gas adsorption/desorption measurements on various adsorbents at liquid nitrogen of temperature 77.3 K were performed. Surface area of each adsorbent was determined by the Brunauer, Emmett and Teller (BET) plot of nitrogen adsorption data. Pore size distribution was measured by the Horvath and Kawazoe (HK) method. As of the adsorption/desorption isotherms, FX-400 shows very small hysteresis when the value of P/P_o exceeds 0.4, while KF-1000 has no hysteresis in the whole range of P/P_o. The adsorption capacity of FX-400 is about 30% higher than that of KF-1000. The adsorption equilibrium data of activated carbon fiber (ACF)-methanol are presented and correlated with simple equations. The adsorption equilibrium data of ACF (KF-1000)-water also presented in order to facilitate comparison with those of ACFs-methanol pair. The results will contribute significantly in designing the adsorber/desorber heat exchanger for thermally driven adsorption cooling system.     

Theoretical and experimental study on indicator diagram of twin screw refrigeration compressor

In this paper a new mathematical model for calculating the indicator diagram of twin screw refrigeration compressor is presented firstly. The geometric parameters related to the rotation angle of male rotor are used in the model such as groove volume, suction and discharge port area, slide valve bypass port area, leakage area etc. The effects of internal leakage through five paths, oil injection, gas–oil heat transfer, refrigerant property and partial loading etc. are taken into account simultaneously and separately in the theoretical study. To verify the model and the calculated p–V indicator diagram, experimental recording of p–V indicator diagram of twin screw refrigeration compressor is carried out. Various indicator diagrams are recorded successfully by a small pressure sensor embedded in the bottom of female rotor at the discharge side. The results of theoretical calculation are in good agreement with the measured data, which lead to conclusion that the model can be used as a powerful tool for performance prediction and product development.     

R32制冷剂空调压缩机应用试验研究

R22 制冷剂替换在即,R32 制冷剂是一种潜在的且经济的替代制冷剂.本文通过分析R32制冷剂的物理性质和理论热工循环参数,并采用空调用涡旋式压缩机进行试验测试,同时与 R410A 制冷剂进行试验对比.试验结果表明,R32 制冷剂替代当前的 R22 制冷剂作为空调制冷剂应用,对于空调用涡旋式压缩机来说,其整体表现与 R410A 制冷剂相类似.但为了取得更好的性能和可靠性,压缩机应针对 R32 制冷剂在空调工况应用时压力高、排气温度高的特点进行设计改进.     

套管管束式换热器换热特性试验研究

清华大学核能与新能源技术研究院对具有特殊结构的套管管束换热器(其传热单元由带螺旋肋片的外套管和带微波浪弯的内套管组成,通过自身结构实现传热管的支撑和定位)的换热特性进行了试验研究.试验结果表明,与一般流道的换热性能相比,不规则环形窄缝流道的换热系数不仅降低,而且随雷诺数的变化趋势也较平缓;外套管管间流道的换热系数降低,但变化趋势与普通流道相同.根据试验数据,采用分离系数法,拟合出了不规则环形窄缝流道和外套管管间流道的换热公式.